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1.
  • Álvarez-Fernández, Noemi, et al. (author)
  • Approaching mercury distribution in burial environment using PLS-R modelling
  • 2021
  • In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 11:1
  • Journal article (peer-reviewed)abstract
    • Mercury environmental cycle and toxicology have been widely researched. Given the long history of mercury pollution, researching mercury trends in the past can help to understand its behaviour in the present. Archaeological skeletons have been found to be useful sources of information regarding mercury loads in the past. In our study we applied a soil multi-sampling approach in two burials dated to the 5th to 6th centuries AD. PLRS modelling was used to elucidate the factors controlling mercury distribution. The model explains 72% of mercury variance and suggests that mercury accumulation in the burial soils is the result of complex interactions. The decomposition of the bodies not only was the primary source of mercury to the soil but also responsible for the pedogenetic transformation of the sediments and the formation of soil components with the ability to retain mercury. The amount of soft tissues and bone mass also resulted in differences between burials, indicating that the skeletons were a primary/secondary source of mercury to the soil (i.e. temporary sink). Within burial variability seems to depend on the proximity of the soil to the thoracic area, where the main mercury target organs were located. We also conclude that, in coarse textured soils, as the ones studied in this investigation, the finer fraction (i.e. silt + clay) should be analysed, as it is the most reactive and the one with the higher potential to provide information on metal cycling and incipient soil processes. Finally, our study stresses the need to characterise the burial soil environment in order to fully understand the role of the interactions between soil and skeleton in mercury cycling in burial contexts.
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2.
  • Álvarez-Fernández, Noemi, et al. (author)
  • Atmospheric mercury pollution deciphered through archaeological bones
  • 2020
  • In: Journal of Archaeological Science. - : Elsevier BV. - 0305-4403 .- 1095-9238. ; 119
  • Journal article (peer-reviewed)abstract
    • Mercury is a major environmental pollutant extensively used by humans, whose pollution dates back at least to c. 3250 BCE (South Iberian Peninsula). As it happens today, past populations were mostly affected by low dose chronic mercury exposure, with levels that varied with the intensity of some anthropogenic activities (mining and metallurgy in particular). Despite its toxic nature, mercury impact in humans themselves has been hardly addressed by Archaeology. The aim of this research is to increase our knowledge on mercury levels in past populations by 1) analysing human (cortical) bone from skeletons recovered in a necropolis from NW Iberia covering contrasting periods of atmospheric pollution: Roman, AD 1st to 4th centuries, and post-Roman, AD 5th to 7th centuries; 2) considering bone type variability; 3) contextualizing our findings with previous works. Samples from 3 types of bone (n = 143) as well as soils/sediments associated to the burials (n = 34) were analysed. Mercury concentrations in soil were below 5 ng g(-1), while the average in bone was 36 +/- 52 ng g(-1), making post-depositional incorporation unlikely. We found significant differences between the two periods (Romans: 54 +/- 60 ng g(-1), post-Romans: 21 +/- 23 ng g(-1)), but no effect of type of bone, sex, age, social status or diet of the individuals. Our results agree with the chronology of mercury pollution reconstructed from a local peatland, which suggests a predominant atmospheric source. This fact contrasts with previous research in which high mercury concentrations were mainly related to post-mortem burial customs and pre-mortem medical treatment and poisoning. Thus, mercury distribution in past communities was possibly more complex than previously thought, with different pre- and post-mortem sources interacting. Furthermore, our research also supports the use of archaeological bone as environmental archive of metal pollution, when metal cultural exposure is low.
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3.
  • Álvarez-Fernández, Noemi, et al. (author)
  • Structural equation modelling of mercury intra-skeletal variability on archaeological human remains
  • 2022
  • In: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 851, part 1
  • Journal article (peer-reviewed)abstract
    • Archaeological burial environments are useful archives to investigate the long-term trends and the behaviour of mercury. In order to understand the relationship between mercury, skeletons and soil, we applied Partial Least Squares - Structural Equation Modelling (PLS-SEM) to a detailed, multisampling (n = 73 bone samples +37 soil samples) design of two archaeological graves dating to the 6th to 7th centuries CE (A Lanzada site, NW Spain). Mercury content was assessed using a DMA-80, and data about bone structure and the grave soil/sediments were obtained using FTIR-ATR spectroscopy. The theoretical model is supported by proxies of bone structure, grave soil/sediments, and location of the bone within the skeleton. The general model explained 61 % of mercury variance. Additionally, Partial Least Square – Prediction Oriented Segmentation (PLS-POS) was also used to check for segmentation in the dataset. POS revealed two group of samples depending on the bone phase (hydroxyapatite or collagen) controlling the Hg content, and the corresponding models explained 86 % and 76 % of Hg variance, respectively. The results suggest that mercury behaviour in the graves is complex, and that mercury concentrations were influenced by i) the ante-mortem status of the bone matrix, related to the weight of each bone phase; ii) post-mortem evolution of bone crystallinity, where bone loses mercury with increasing alteration; and iii) the proximity of the skeletal pieces to mercury target organs, as decomposition and collapse of the thoracic and abdominal soft tissues causes a secondary mercury enrichment in bones from the body trunk during early post-mortem. Skeletons provide a source of mercury to the soil whereas soil/sediments contribute little to skeletal mercury content.
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4.
  • Biester, Harald, et al. (author)
  • Mercury in mires
  • 2006
  • In: Peatlands. - : Elsevier. - 9780080468051 - 9780444528834 ; , s. 465-478
  • Book chapter (peer-reviewed)abstract
    • This chapter illustrates that a better understanding of the behavior of mercury in the environment is needed for a number of reasons. For example, increased biomagnification of mercury in aquatic food chains, especially in fish, and enhanced accumulation in remote areas such as the Arctic have been observed in the last few decades. Mercury toxicity in aquatic ecosystems is of particular concern, with the role of methylmercury (MeHg) being critical. This compound can be concentrated by more than a million times in the aquatic food chain. Biogeochemical studies and monitoring programs that include direct measurements of wet deposition or indirect measurements based on biomonitoring of forest mosses, have established that anthropogenic activities have affected the global cycling of mercury. Although a precise link has yet to be made between the increased content of mercury in biota and the increased accumulation rates observed in natural environmental archives, such as peat, lake sediments, and glacial ice, there is broad consensus that these archives provide a means to reconstruct atmospheric deposition trends at local, regional, and global scales.
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5.
  • Biester, Harald, et al. (author)
  • Modeling the Past Atmospheric Deposition of Mercury Using Natural Archives
  • 2007
  • In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 41:14, s. 4851-4860
  • Journal article (peer-reviewed)abstract
    • Historical records of mercury (Hg) accumulation in lake sediments and peat bogs are often used to estimate human impacts on the biogeochemical cycling of mercury. On the basis of studies of lake sediments, modern atmospheric mercury deposition rates are estimated to have increased by a factor of 3-5 compared to background values: i.e., from about 3-3.5 g Hg m-2 yr-1 to 10-20 g Hg m-2 yr-1. However, recent studies of the historical mercury record in peat bogs suggest significantly higher increases (9-400 fold, median 40×), i.e., from about 0.6-1.7 g Hg m-2 yr -1 to 8-184 g Hg m-2 yr -1. We compared published data of background and modern mercury accumulation rates derived from globally distributed lake sediments and peat bogs and discuss reasons for the differences observed in absolute values and in the relative increase in the industrial age. Direct measurements of modern wet mercury deposition rates in remote areas are presently about 1-4 g m-2 yr -1, but were possibly as high as 20 g Hg m-2 yr -1 during the 1980s. These values are closer to the estimates of past deposition determined from lake sediments, which suggests that modern mercury accumulation rates derived from peat bogs tend to over-estimate deposition. We suggest that smearing of 210Pb in the uppermost peat sections contributes to an underestimation of peat ages, which is the most important reason for the overestimation of mercury accumulation rates in many bogs. The lower background mercury accumulation rates in peat as compared to lake sediments we believe is the result of nonquantitative retention and loss of mercury during peat diagenesis. As many processes controlling time-resolved mercury accumulation in mires are still poorly understood, lake sediments appear to be the more reliable archive for estimating historical mercury accumulation rates.
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6.
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7.
  • Cooke, Colin A., et al. (author)
  • Environmental archives of atmospheric Hg deposition : a review
  • 2020
  • In: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 709
  • Research review (peer-reviewed)abstract
    • Environmental archives offer an opportunity to reconstruct temporal trends in atmospheric Hg deposition at various timescales. Lake sediment and peat have been the most widely used archives; however, new records from ice, tree rings, and the measurement of Hg stable isotopes, are offering new insights into past Hg cycling. Preindustrial Hg deposition has been studied over decadal to millennial timescales extending as far back as the late Pleistocene. Exploitation of mercury deposits (mainly cinnabar) first began during the mid to late Holocene in South America, Europe, and Asia, but increased dramatically during the Colonial era (1532-1900) for silver production. However, evidence for preindustrial Hg pollution is restricted to regions directly downwind or downstream of cinnabar or precious metal mining centers. Excluding these areas, there has been an approximately four-fold increase in atmospheric deposition globally over the industrial era (i.e., since 1800-1850), though regional differences exist, especially during the early 20th Century. Lake sediments, peat, ice, and tree rings are all influenced by (and integrate) a range of processes. For example, lake sediments are influenced by atmospheric deposition, sediment focusing, and the input of allochthonous material from the watershed, peat records reflect atmospheric deposition and biotic uptake, ice cores are a record of Hg scrubbed during precipitation, and tree rings record atmospheric concentrations. No archive represents an absolute record of past Hg deposition or concentrations, and post-depositional transformation of Hg profiles remains an important topic of research. However, natural archives continue to provide important insight into atmospheric Hg cycling over various timescales.
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8.
  • Ferro-Vázquez, Cruz, et al. (author)
  • Tracing Pb Pollution Penetration in Temperate Podzols
  • 2017
  • In: Land Degradation and Development. - : John Wiley & Sons. - 1085-3278 .- 1099-145X. ; 28:8, s. 2432-2445
  • Journal article (peer-reviewed)abstract
    • We combine high-resolution soil sampling with lead (Pb) analyses (concentrations and stable isotopes) in two temperate podzols, together with previous data obtained with selective Al and Fe dissolution techniques. We aim to assess how atmospheric Pb is incorporated into the soils during pedogenesis. Partial least squares modelling for Pb concentrations shows that the podzolization process has the largest effect on Pb concentration (803% of the variance). The proportion of inorganic secondary compounds, the input of fresh organic matter from the soil surface and the relative abundance of Fe versus Al are responsible for a small part of the Pb concentration variance. Lead isotopic composition (Pb-206/Pb-207 ratios) depends on soil organic matter content either fresh/poorly humified (573% of the variance) or humified (247% of the variance). The Pb linked to inorganic compounds and the overall podzolization process play a minor role in isotopic signature (53 and 37% of the variance respectively). Soil pH appears to be the controlling variable of the different transport and retention mechanisms. The relatively low isotopic ratios observed in spodic horizons result from geogenic Pb released through the preferential dissolution of the isotopically distinct most weatherable minerals of the parent material in the eluvial horizons, which undergoes downward mobilization. An accurate knowledge of soil reactive components and formation mechanisms is essential to a correct diagnose of the scope of Pb pollution and a more effective design of remediation strategies.
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9.
  • Gallego-Sala, Angela V., et al. (author)
  • Latitudinal limits to the predicted increase of the peatland carbon sink with warming
  • 2018
  • In: Nature Climate Change. - : Springer Science and Business Media LLC. - 1758-678X .- 1758-6798. ; 8:10, s. 907-
  • Journal article (peer-reviewed)abstract
    • The carbon sink potential of peatlands depends on the balance of carbon uptake by plants and microbial decomposition. The rates of both these processes will increase with warming but it remains unclear which will dominate the global peatland response. Here we examine the global relationship between peatland carbon accumulation rates during the last millennium and planetary-scale climate space. A positive relationship is found between carbon accumulation and cumulative photosynthetically active radiation during the growing season for mid- to high-latitude peatlands in both hemispheres. However, this relationship reverses at lower latitudes, suggesting that carbon accumulation is lower under the warmest climate regimes. Projections under Representative Concentration Pathway (RCP)2.6 and RCP8.5 scenarios indicate that the present-day global sink will increase slightly until around AD 2100 but decline thereafter. Peatlands will remain a carbon sink in the future, but their response to warming switches from a negative to a positive climate feedback (decreased carbon sink with warming) at the end of the twenty-first century.
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10.
  • García-López, Zaira, et al. (author)
  • Understanding Necrosol pedogenetical processes in post-Roman burials developed on dunes sands
  • 2022
  • In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 12
  • Journal article (peer-reviewed)abstract
    • In Archaeology much emphasis is dedicated to bone preservation, but less attention is paid to the burial soil (i.e., Necrosol), despite its crucial role in governing the geochemical environment. The interaction between human remains and sediments starts after inhumation, leading to bidirectional physico-chemical changes. To approach these complex, bidirectional processes, we sampled at high resolution (n = 46) two post-Roman wooden coffin burials (one single and another double), and the coeval paleosol (n = 20; nearby pedo-sedimentary sequence). The samples were analysed for physical (grain size, colour) and chemical (pH; LOI; elemental composition: FTIR-ATR, XRF, C, N) properties. Principal component analysis enabled to identify five main pedogenetical processes: decalcification, melanization, acidification, neoformation of secondary minerals (i.e., clays) and enrichment in phosphorus. Melanization, acidification and phosphorous enrichment seem to be convergent processes in Necrosols—irrespective of the parent material. Decalcification may be restricted to carbonate containing soil/sediments. Despite not mentioned in previous research, clay formation might also be an overall process. Compared to the local, coeval paleosol, pedogenesis in the studied burial soils was low (double burial) to moderate (single burial). Our results also emphasize the need to study the finer soil fractions, as they provide clues both on soil formation and bone diagenesis.
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11.
  • García-Moreno, Carlos D., et al. (author)
  • A Stable Isotope Approach to Roman Diet and Its Legacy in Late Antiquity in Hispania and the Western Empire
  • 2022
  • In: Environmental Archaeology. - : Informa UK Limited. - 1461-4103 .- 1749-6314.
  • Journal article (peer-reviewed)abstract
    • Whether a Roman diet existed is a constant issue in Classical archaeology, as it is also its persistence in late Antiquity. Here, we review the isotopic composition (δ13Ccol and δ15Ncol ) of 15 (n = 384) necropolis dating to the 1st to 8th centuries AD from Hispania. We worked with human and animal raw data and calculated the human enrichment regarding herbivoreś average. Although diet was not homogeneous, intra-site variability was greater than inter-site variability. The results show a diet characterised by consumption of C3 plants with some intake of meat/eggs/dairy products from terrestrial herbivores fed on C3 plants, with no clear differences between periods. NW Hispanic sites show an exceptional consumption of C4 plants (millet) and marine resources. There is a slight correlation between δ15N and distance from the sea, but marine resource consumption seems to have been mostly absent or low. Most sites studied were rural or located at the coast and this may result in some bias in the interpretation. Therefore, more effort in analysing inland urban sites is needed. The comparison with sites from France, Britain and Italy indicates a slightly higher dependence on millets in Hispania, which can be traced back to the Iron Age. The data suggest the existence of a certain homogeneity in diet that persisted in later centuries while displaying specificities and local adaptations. 
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12.
  • Jones, Samantha E., et al. (author)
  • Lake and crannog : A 2500-year palaeoenvironmental record of continuity and change in NE Scotland
  • 2022
  • In: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 285
  • Journal article (peer-reviewed)abstract
    • Wetland environments have been important resources for human habitation since prehistoric times and in parts of northern Europe these have witnessed the construction of artificial islet settlements, known as ‘crannogs’ in Scotland and Ireland. This paper presents a high-resolution multi-proxy palaeoenvironmental study from the Loch of Leys, Aberdeenshire, Scotland, the site of a recently excavated crannog that provides a chronological context for its inhabitation. The combined datasets demonstrate that the first occupation from AD 20–210 coincided not only with a transitional phase from lake to wetland (mire) but also with the timing of the first major Roman campaigns in northeast Scotland. Techniques including microfossil analysis, geochemistry, IR-spectroscopy and physical properties integrated with archaeological and historical records have helped to better define both natural changes that took place in the wetland environment and human activity (agriculture, fires, metal working) spanning the Roman Iron Age through to the present. This has allowed a better understanding of the responses of existing Iron Age communities to Roman military activity (e.g. through continuity or change in land use) as well as the resources exploited in frontier zones during the Roman and post Roman eras. This has wider significance not just for Scotland but also for other parts of Europe that had similar frontiers and conflict zones during the Roman period.
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13.
  • Kaal, Joeri, et al. (author)
  • Diagenetic effects on pyrolysis fingerprints of extracted collagen in archaeological human bones from NW Spain, as determined by pyrolysis-GC-MS
  • 2016
  • In: Journal of Archaeological Science. - : Elsevier BV. - 0305-4403 .- 1095-9238. ; 65, s. 1-10
  • Journal article (peer-reviewed)abstract
    • Ancient collagen is used as archive for multiple pre-mortem traits. Testing the quality of the collagen extract is a common concern of those who engage in the reconstruction of ancient diets. The aim of this study is to improve our understanding of the pyrolysis fingerprints of human bone collagen especially in relation with diagenetic alteration. Pyrolysis-GC-MS was applied to 28 collagen samples extracted from archaeological human bone, corresponding to different chronological periods (Bronze Age to post Medieval period; 1900 BC-1800 AD) and different types of burial environment (acidic and alkaline) from NW Spain. Collagen was extracted following the common methodology used in paleodiet analysis, and a commercial gelatin sample was included for comparison. Data evaluation was based on 58 pyrolysis products using Principal Components Analysis (PCA). Principal component 1 (PC1, 45% of total variance) was related to the relative abundances of pyrolysis products of specific amino acids, with relatively degraded samples having larger proportions of the pyrolysis products of Pro/Hyp, Phe and Ala, while more intact samples showed larger proportions of Tyr, Trp and pyrolysis products of unspecific amino acid origin. PC1 scores were related to the period to which the samples corresponded, which reflects differences in diagenetic impact, probably controlled by a combination of age and burial deposit characteristics. PC2 (15%) probably reflects the well-known effects of disruption of the amino acid sequence (depolymerization), causing a decline in dimerization products (diketopiperazines) upon pyrolysis. This process was more intense in the collagen samples from acidic deposits than in the samples from alkaline deposits (a calcareous cave and coastal sand deposits with biogenic carbonates). The relationships between the PCA and individual pyrolysis products with known parameters of collagen quality (% C, % N, C/N ratio, % extractable collagen) were generally insignificant or weak. This might be explained by the rather narrow C/N range (3.19-3.36) of the samples, which had to meet the criteria for suitability for paleodiet analysis. Moreover, there was no significant relation between the isotopic composition of the extracted collagen (613C, 815N) and pyrolyzate composition, suggesting that diagenesis has little effect on the isotopic fingerprints used in palaeodietary studies. Finally, no substantial contamination of microbial or exogenous tissue from the deposition environment to the osteological collagen extracts was identified. It is concluded that the delta C-13 and delta N-15 as proxies of palaeodiet from these diverse necropoleis in NW Spain is sustained.
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14.
  • Kaal, Joeri, et al. (author)
  • Reconstruction of 7500 years of coastal environmental change impacting seagrass ecosystem dynamics in Oyster Harbour (SW Australia)
  • 2020
  • In: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier BV. - 0031-0182 .- 1872-616X. ; 558
  • Journal article (peer-reviewed)abstract
    • Seagrass ecosystems, which have important functions such as coastal protection and blue carbon sequestration, are threatened by anthropogenic pressure including climate change. Long-term data series from seagrass sedimentary archives (mats) can be used to understand natural cycles of environmental change and answer key questions related to contemporary management. A 7500 yr sediment record from Posidonia australis meadows in Oyster Harbour (Albany, SW Australia) was subjected to multiproxy reconstruction by means of pigment analysis (UHPLC), analytical pyrolysis (Py-GC-MS), carbonate content, delta C-13 and delta N-15 stable isotope ratios, organic C (C-org) content, C-org/N ratio and glomalin-related soil proteins (GASP). The study revealed a brackish lagoon (7500-7000 cal yr BP) that was transformed in an open marine environment (7000-4100 cal yr BP) due to Holocene transgression. Earliest evidence of seagrass establishment was detected around 4500 cal yr BP, and meadow extension accelerated between 4100 and 3700 cal yr BP. The meadow environment was surprisingly resistant against environmental perturbations, as the mat, composed of P. australis seagrass fibres embedded within a siliciclastic mineral matrix containing biogenic carbonates, continued to develop steadily until 190 cal yr BP (1830 CE). Then, shifts in several proxies (pigments, GASP) showed evidence of terrestrial runofftriggered eutrophication/turbidity (likely driven by forest clearance and agricultural activities after European settlement), but the seagrass showed resilience (no decline of the proportion of seagrass-derived C-org). By contrast, since similar to 1930 CE seagrass retreat is evident in the biogeochemical record: lighter delta C-13 values, lower lignin abundance and shifts in pigment abundance and types, affecting the balance between seagrass inputs and alternative sources, as was observed in previous studies of the area. The findings show that pigment proxies are useful early indicators of shifts in seagrass ecosystem condition, while lignocellulose and other pyrolysis products are useful proxies of more profound ecosystem alterations that influence seagrass abundance. The record indicates that the climax seagrass ecosystem condition, which prevailed for several millennia, had been impacted over the last century. Management of seagrass and coastal ecosystems should aim to avoid crossing ecological thresholds and diminish local impacts aggravating those of global change.
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15.
  • Kaal, Joeri, et al. (author)
  • Seasonal changes in molecular composition of organic matter in lake sediment trap material from Nylandssjon, Sweden
  • 2015
  • In: Organic Geochemistry. - : Elsevier BV. - 0146-6380 .- 1873-5290. ; 83-84, s. 253-262
  • Journal article (peer-reviewed)abstract
    • The origin and degradation/preservation state of organic matter (OM) in lacustrine systems can be studied using its molecular composition. Pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) allows rapid assessment of OM-rich samples and has proven a useful tool for peat, lacustrine and marine deposits, but is rarely applied specifically to lake environments prone to the formation of varves (annually laminated sediments), which are used frequently for palaeoenvironmental reconstruction. We applied Py-GC-MS to a 3.5 yr record of sediment trap samples collected from Nylandssjon in northern Sweden to determine the usefulness of the method for improving knowledge of OM dynamics in varved lakes. It appeared that seasonal variation controlled the pyrolysis fingerprints: intact polysaccharides and lignin from vascular plants, chitin from arthropods and chlorophyll from algae were concentrated in spring and summer traps, whereas winter trap samples were enriched mainly in degraded components, as OM slowly trickled down under a thick layer of ice. A secondary diagenetic process involving sulfurisation of phytadienes was recognised via isoprenoid thiophenes, with no clear seasonal trend, probably because it occurred under anoxic conditions at the lake bottom. The N-containing compounds from proteins in algae and chitin in arthropods were abundant in all samples, indicating that the dominant flux of varve OM was autochthonous in origin. We conclude that Py-GC-MS has significant potential for identifying the variability in parent material (source organisms and degradation state) and could become a valuable tool for palaeoenvironmental reconstruction from varved lake sediments. 
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16.
  • Kirkinen, Tuija, et al. (author)
  • Preservation of microscopic fur, feather, and bast fibers in the Mesolithic ochre grave of Majoonsuo, Eastern Finland
  • 2022
  • In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 17:9
  • Journal article (peer-reviewed)abstract
    • The study of animal and plant fibers related to grave furnishing, garments, and grave goods in thousands-of-year-old burials provides new insights into these funerary practices. Their preservation presupposes favorable conditions, where bacterial and fungal activity is at a minimum, as in anaerobic, wet, salty, arid, or frozen environments. The extreme acidic-soil environments (i.e., podzols) of Finland pose a challenge when it comes to studying funerary deposits, as human remains are rarely found. However, its potential to preserve microparticles allows us to approach the funerary event from a totally different point of view. Here, we present the first multiproxy analyses of a Mesolithic deposit from Finland. A red-ochre burial of a child found in Majoonsuo is studied by analyzing 1) microscopic fibers, 2) fatty acids, and 3) physical-chemical (CIELab color, pH, grain size) properties of 60 soil samples and associated materials. The microscopic fibers evidenced the remains of waterfowl downy feathers, a falcon feather fragment, canid and small rodent hairs as well as bast fibers. These could have been used in furnishing the grave and as ornaments or clothes. Canid hairs could belong to a dog inhumation, or more likely to canid fur used as grave good/clothes. Samples with microparticles have more long-chain and unsaturated fatty acids, although animal species identification was not possible. Soil properties indicate that the burial was made in the local soil, adding homogeneous red ochre and removing the coarser material; no bioturbation was found. The highly acidic sandy soil, together with a slight increase in finer particles when ochre is abundant, probably resulted in micro-scale, anoxic conditions that prevented bacterial attack. This study reveals the first animal hairs and feathers from a Finnish Mesolithic funerary context, and provides clues about how their preservation was possible.
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17.
  • Kylander, Malin, 1977-, et al. (author)
  • A novel geochemical approach to paleorecords of dust deposition and effective humidity: 8500 years of peat accumulation at Store Mosse (the "Great Bog") , Sweden )
  • 2013
  • In: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 69, s. 69-82
  • Journal article (peer-reviewed)abstract
    • Both bog surface wetness and atmospheric dust deposition are intricately linked to changes in the hydrological cycle and pairing these types of records at the same site provides complementary information. Here a peat core from Store Mosse in southern Sweden covering the last 8500 years was used to make a high-resolution paleoclimate reconstruction based on a combination of bog development, colourimetric humification and inorganic geochemistry data. The coupling of Principal Component Analysis with changepoint modelling allowed for precise linking of changes in bog surface wetness and dust deposition records.A long-term trend towards warm (and possibly wet) conditions starts ca 8150 cal yr BP and culminates with the most pronounced conditions from 6900 to 6600 cal yr BP. The most significant arid period at Store Mosse occurred between 6500 and 5600 cal yr BP during which dust deposition was significantly higher. Wetter conditions dominate from 5500 to 4980 cal yr BP as the transition from the Hypsithermal and into the Neoglacial is made. After a shift to drier conditions, humification enters a more stable period that lasts from 4525 until 3200 cal yr BP. It is during this time that the first possible anthropogenic dust signals occur at ca 4200 cal yr BP. From 3200 cal yr BP to present humification generally shows a long-term decline moving towards wetter conditions. The main exceptions are during the transition from the Neoglacial to Roman Warm Period which is registered as a significantly wetter period and two dry periods recorded 2365 to 2155 cal yr BP and 1275–1105 cal yr BP. In general, the observed changes agree well with regional records of effective humidity and temperature. The high temporal resolution of the Store Mosse record reveals that palaeoclimatic change over the last 8500 years in southern Sweden has had a complex and variable structure.
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18.
  • Kylander, Malin E., et al. (author)
  • It's in your glass : a history of sea level and storminess from the Laphroaig bog, Islay (southwestern Scotland)
  • 2020
  • In: Boreas. - : Wiley. - 0300-9483 .- 1502-3885. ; 49:1, s. 152-167
  • Journal article (peer-reviewed)abstract
    • Severe winter windstorms have become an increasingly common occurrence over recent decades in northwestern Europe. Although there exists considerable uncertainty, storminess is projected to increase in the future. On centennial to millennial time scales in particular, the mechanisms forcing storminess remain unsettled. We contribute to available palaeostorm records by reconstructing changes over the last 6670 years using a coastal peat sequence retrieved from the ombrotrophic Laphroaig bog on Islay, southwestern Scotland. We use a combination of ash content, grain size and elemental chemistry to identify periods of greater storminess, which are dated to 6605, 6290-6225, 5315-5085, 4505, 3900-3635, 3310-3130, 2920-2380, 2275-2190, 2005-1860, 1305-1090, 805-435 and 275 cal. a BP. Storm signals in the first half of the record up to similar to 3000 cal. a BP are mainly apparent in the grain-size changes. Samples from this time period also have a different elemental signature than those later in the record. We speculate that this is due to receding sea levels and the consequent establishment of a new sand source in the form of dunes, which are still present today. The most significant events and strongest winds are found during the Iron Ages Cold Epoch (2645 cal. a BP), the transition into, and in the middle of, the Roman Ages Warm Period (2235 and 1965 cal. a BP) and early in the Little Ice Age (545 cal. a BP). The Laphroaig record generally agrees with regionally relevant peat palaeostorm records from Wales and the Outer Hebrides, although the relative importance of the different storm periods is not the same. In general, stormier periods are coeval with cold periods in the region as evidenced by parallels with increased ice-rafted debris in the North Atlantic, highlighting that sea-ice conditions could impact future storminess and storm track position.
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19.
  • Kylander, Malin E., et al. (author)
  • Late glacial (17,060-13,400 cal yr BP) sedimentary and paleoenvironmental evolution of the Sekhokong Range (Drakensberg), southern Africa
  • 2021
  • In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 16:3
  • Journal article (peer-reviewed)abstract
    • Southern Africa sits at the junction of tropical and temperate systems, leading to the formation of seasonal precipitation zones. Understanding late Quaternary paleoclimatic change in this vulnerable region is hampered by a lack of available, reliably-dated records. Here we present a sequence from a well-stratified sedimentary infill occupying a lower slope basin which covers 17,060 to 13,400 cal yr BP with the aim to reconstruct paleoclimatic variability in the high Drakensberg during the Late Glacial. We use a combination of pollen, total organic carbon and nitrogen, delta C-13, Fourier transform infrared spectroscopy attenuated total reflectance (FTIR-ATR) spectral and elemental data on contiguous samples with high temporal resolution (10 to 80 years per sample). Our data support a relatively humid environment with considerable cold season precipitation during what might have been the final stage of niche-glaciation on the adjoining southern aspects around 17,000 cal yr BP. Then, after an initial warmer and drier period starting similar to 15,600 cal yr BP, we identify a return to colder and drier conditions with more winter precipitation starting similar to 14,380 cal yr BP, which represents the first local evidence for the Antarctic Cold Reversal (ACR) in this region. On decadal to centennial timescales, the Late Glacial period was one marked by considerable climatic fluctuation and bi-directional environmental change, which has not been identified in previous studies for this region. Our study shows complex changes in both moisture and thermal conditions providing a more nuanced picture of the Late Glacial for the high Drakensburg.
  •  
20.
  • Kylander, Malin E., et al. (author)
  • Lead Penetration and Leaching in a Complex Temperate Soil Profile
  • 2008
  • In: Environmental Science and Technology. ; 42, s. 3177-3184
  • Journal article (peer-reviewed)abstract
    • The documented loss of anthropogenic Pb from soil organic horizons and its migration into the mineral soil below has raised several environmental concerns, especially over the leaching of Pb into groundwater aquifers and subsequently into other environmental compartments of the ecosystem. Here, a complex colluvial soil formed over the last 10,000 years in NW Spain is studied. The objective is to evaluate the behavior of Pb in soils, including its migration rates and the potential use of complex soils as archives of atmospheric Pb pollution. To this end, Pb concentrations and Pb isotope ratios for total soil, and for acid-extractable (0.5 M HNO3) and residual fractions were determined. We show that the acid-extractable fraction is more radiogenic than the residual one in most of the soil profile and that this relationship is reversed in the surface layers (<15 cm) where pollution is greatest. Radiogenic Pb seems to have been leached out during rock weathering and pedogenesis of the soil. Comparison with a nearby peat record of atmospheric Pb deposition over the last 8 kyears demonstrates that though signals from pollution are detected in the soil record, the soil itself does not provide an accurate reconstruction of Pb deposition. On the basis of the history of soil formation the most likely Pb migration rate is estimated at approximately 0.01 cm year−1. At this migration rate Pb would be retained in the soil column for ~20 kyear. In other words, there is no evidence for the relatively rapid movement of Pb into the soil.
  •  
21.
  • Kylander, Malin E., et al. (author)
  • Potentials and problems of building detailed dust records using peat archives : An example from Store Mosse (the "Great Bog"), Sweden
  • 2016
  • In: Geochimica et Cosmochimica Acta. - : Elsevier BV. - 0016-7037 .- 1872-9533 .- 0046-564X. ; 190, s. 156-174
  • Journal article (peer-reviewed)abstract
    • Mineral dust deposition is a process often overlooked in northern mid-latitudes, despite its potential effects on ecosystems. These areas are often peat-rich, providing ample material for the reconstruction of past changes in atmospheric deposition. The highly organic (up to 99% in some cases) matrix of atmospherically fed mires, however, makes studying the actual dust particles (grain size, mineralogy) challenging. Here we explore some of the potentials and problems of using geochemical data from conservative, lithogenic elements (Al, Ga, Rb, Sc, Y, Zr, Th, Ti and REE) to build detailed dust records by using an example from the 8900-yr peat sequence from Store Mosse (the "Great Bog"), which is the largest mire complex in the boreo-nemoral region of southern Sweden. The four dust events recorded at this site were elementally distinct, suggesting different dominant mineral hosts. The oldest and longest event (6385-5300 cal yr BP) sees a clear signal of clay input but with increasing contributions of mica, feldspar and middle-REE- rich phosphate minerals over time. These clays are likely transported from a long-distance source (< 100 km). While dust deposition was reduced during the second event (5300-4370 cal yr BP), this is the most distinct in terms of its source character with [Eu/Eu*] UCC revealing the input of plagioclase feldspar from a local source, possibly active during this stormier period. The third (2380- 2200 cal yr BP) and fourth (1275-1080 cal yr BP) events are much shorter in duration and the presence of clays and heavy minerals is inferred. Elemental mass accumulation rates reflect these changes in mineralogy where the relative importance of the four dust events varies by element. The broad changes in major mineral hosts, grain size, source location and approximated net dust deposition rates observed in the earlier dust events of longer duration agree well with paleoclimatic changes observed in northern Europe. The two most recent dust events are much shorter in duration, which in combination with evidence of their local and regional character, may explain why they have not been seen elsewhere. 
  •  
22.
  • Kylander, Malin E., 1977-, et al. (author)
  • Storm chasing : Tracking Holocene storminess in southern Sweden using mineral proxies from inland and coastal peat bogs
  • 2023
  • In: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 299, s. 107854-
  • Journal article (peer-reviewed)abstract
    • Severe extratropical winter storms are a recurrent feature of the European climate and cause widespread socioeconomic losses. Due to insufficient long-term data, it remains unclear whether storminess has shown a notable response to changes in external forcing over the past millennia, which impacts our ability to project future storminess in a changing climate. Reconstructing past storm variability is essential to improving our understanding of storms on these longer, missing timescales. Peat sequences from coastal ombrotrophic bogs are increasingly used for this purpose, where greater quantities of coarser grained beach sand are deposited by strong winds during storm events. Moving inland however, storm intensity decreases, as does sand availability, muting potential paleostorm signals in bogs. We circumvent these issues by taking the innovative approach of using mid-infrared (MIR) spectral data, supported by elemental information, from the inorganic fraction of Store Mosse Dune South (SMDS), a 5000-year-old sequence from a large peatland located in southern Sweden. We infer past changes in mineral composition and thereby, the grain size of the deposited material. The record is dominated by quartz, whose coarse nature was confirmed through analyses of potential local source sediments. This was supported by further mineralogical and elemental proxies of atmospheric input. Comparison of SMDS with within-bog and regionally relevant records showed that there is a difference in proxy and site response to what should be similar timing in shifts in storminess over the-100 km transect considered. We suggest the construction of regional storm stacks, built here by applying changepoint modelling to four transect sites jointly. This modelling approach has the effect of reinforcing signals in common while reducing the influence of random noise. The resulting Southern Sweden-Storm Stack dates stormier periods to 4495-4290, 3880-3790, 2885-2855, 2300-2005, 1175-1065 and 715-425 cal yr BP. By comparing with a newly constructed Western Scotland-Storm Stack and proximal dune records, we argue that regional storm stacks allow us to better compare past storminess over wider areas, gauge storm track movements and by extension, increase our understanding of the drivers of storminess on centennial to millennial timescales.
  •  
23.
  • Kylander, malin, et al. (author)
  • Lead Penetration and Leaching in a Complex Temperate Soil Profile
  • 2008
  • In: Environmental Science & Technology. ; 42:9, s. 3177-3184
  • Journal article (peer-reviewed)abstract
    • The documented loss of anthropogenic Pb from soil organic horizons and its migration into the mineral soil below has raised several environmental concerns, especially over the leaching of Pb into groundwater aquifers and subsequently into other environmental compartments of the ecosystem. Here, a complex colluvial soil formed over the last 10,000 years in NW Spain is studied. The objective is to evaluate the behavior of Pb in soils, including its migration rates and the potential use of complex soils as archives of atmospheric Pb pollution. To this end, Pb concentrations and Pb isotope ratios for total soil, and for acid-extractable (0.5 M HNO3) and residual fractions were determined. We show that the acid-extractable fraction is more radiogenic than the residual one in most of the soil profile and that this relationship is reversed in the surface layers (
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24.
  • López-Costas, Olalla, et al. (author)
  • Chemical compositional changes in archaeological human bones due to diagenesis : Type of bone vs soil environment
  • 2016
  • In: Journal of Archaeological Science. - : Elsevier BV. - 0305-4403 .- 1095-9238. ; 67, s. 43-51
  • Journal article (peer-reviewed)abstract
    • Diagenesis in human remains is a subject of growing interest due to the increase in bone chemical studies to reconstruct pre- and post-mortem features in archaeological and forensic sciences. The efforts made during the last decades have solidified our understanding of diagenetic processes; however, their high complexity demands more research to address them empirically, specifically considering factors such as types of soil substratum and skeletal element. In this work, a geochemical study of human remains from the archaeological site of A Lanzada (NW Spain) is performed to understand diagenesis (i.e. chemical alteration) and life environmental exposure. Three types of bone (thoracic, long and cranial) from 30 skeletons of two periods (9 Roman, 21 post-Roman) were analysed by X-ray fluorescence. Bones were recovered from burials located in slightly alkaline (Haplic Arenosol (calcaric)) and acidic (Cambic Umbrisol (humic)) soils. Principal components analysis was applied to extract the main chemical signatures, and analysis of variance to determine the influence of different factors. Bone composition was characterized by four chemical signals related to: i) alteration of bone bioapatite; ii) metal sorption from the soil solution; iii) presence of fine (silt-clay) soil particles; and iv) lead incorporation. Thoracic bones were found to be more sensitive to diagenesis and the burial environment; long bones and crania presented a similar response. Skeletons buried in the acidic soil were significantly poorly preserved. Lead content was higher in bones of the Roman period, which seems to be related to pre-mortem conditions. Previous investigations on palaeopollution in NW Spain enable us to hypothesize that Roman individuals may have been subjected to a high exposure of Pb due to elevated atmospheric metal contamination.
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25.
  • Lopez-Costas, Olalla, et al. (author)
  • Human bones tell the story of atmospheric mercury and lead exposure at the edge of Roman World
  • 2020
  • In: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 710
  • Journal article (peer-reviewed)abstract
    • Atmospheric metal pollution is a major health concern whose roots pre-date industrialization. This study pertains the analyses of ancient human skeletons and compares them with natural archives to trace historical environmental exposure at the edge of the Roman Empire in NW Iberia The novelty of our approach relies on the combination of mercury, lead and lead isotopes. We found over a 700-year period that rural Romans incorporated two times more mercury and lead into their bones than post-Romans inhabiting the same site, independent of sex or age. Atmospheric pollution sources contributed on average 57% (peaking at 85%) of the total lead incorporated into the bones in Roman times, which decreased to 24% after the decline of Rome. These values and accompanying changes in lead isotopic composition mirror changes in atmospheric Pb deposition recorded in local peatlands. Thus, skeletons are a time-transgressive archive reflecting contaminant exposure.
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26.
  • López-Merino, Lourdes, et al. (author)
  • Reconstructing the impact of human activities in a NW Iberian Roman mining landscape for the last 2500 years
  • 2014
  • In: Journal of Archaeological Science. - : Elsevier. - 0305-4403 .- 1095-9238. ; 50, s. 208-218
  • Journal article (peer-reviewed)abstract
    • Little is known about the impact of human activities during Roman times on NW Iberian mining landscapes beyond the geomorphological transformations brought about by the use of hydraulic power for gold extraction. We present the high-resolution pollen record of La Molina mire, located in an area intensely used for gold mining (Asturias, NW Spain), combined with other proxy data from the same peat core to identify different human activities, evaluate the strategies followed for the management of the resources and describe the landscape response to human disturbances. We reconstructed the timing and synchronicity of landscape changes of varying intensity and form occurred before, during and after Roman times. An open landscape was prevalent during the local Late Iron Age, a period of relatively environmental stability. During the Early Roman Empire more significant vegetation shifts took place, reflected by changes in both forest (Corylus and Quercus) and heathland cover, as mining/metallurgy peaked and grazing and cultivation increased. In the Late Roman Empire, the influence of mining/metallurgy on landscape change started to disappear. This decoupling was further consolidated in the Germanic period (i.e., Visigothic and Sueve domination of the region), with a sharp decrease in mining/metallurgy but continued grazing. Although human impact was intense in some periods, mostly during the Early Roman Empire, forest regeneration occurred afterwards: clearances were local and short-lived. However, the Roman mining landscape turned into an agrarian one at the onset of the Middle Ages, characterized by a profound deforestation at a regional level due to a myriad of human activities that resulted in an irreversible openness of the landscape.
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27.
  • Losada, María, et al. (author)
  • Mammal and tree diversity accumulate different types of soil organic matter in the northern Amazon
  • 2023
  • In: iScience. - : Elsevier BV. - 2589-0042. ; 26:3
  • Journal article (peer-reviewed)abstract
    • Diversity of plants and animals influence soil carbon through their contributions to soil organic matter (SOM). However, we do not know whether mammal and tree communities affect SOM composition in the same manner. This question is relevant because not all forms of carbon are equally resistant to mineralization by microbes and thus, relevant to carbon storage. We analyzed the elemental and molecular composition of 401 soil samples, with relation to the species richness of 83 mammal and tree communities at a landscape scale across 4.8 million hectares in the northern Amazon. We found opposite effects of mammal and tree richness over SOM composition. Mammal diversity is related to SOM rich in nitrogen, sulfur and iron whereas tree diversity is related to SOM rich in aliphatic and carbonyl compounds. These results help us to better understand the role of biodiversity in the carbon cycle and its implications for climate change mitigation.
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28.
  • Martínez Cortizas, Antonio, et al. (author)
  • 9000 years of changes in peat organic matter composition in Store Mosse (Sweden) traced using FTIR-ATR
  • 2021
  • In: Boreas. - : Wiley. - 0300-9483 .- 1502-3885. ; 50:4, s. 1161-1178
  • Journal article (peer-reviewed)abstract
    • Store Mosse (the ‘Great Bog’ in Swedish) is one of the most extensive bog complexes in southern Sweden (~77 km2), where pioneering palaeoenvironmental research has been carried out since the early 20th century. This includes, for example, vegetation changes, carbon and nitrogen dynamics, peat decomposition, atmospheric metal pollution, mineral dust deposition, dendrochronology, and tephrochronology. Even though organic matter (OM) represents the bulk of the peat mass and its compositional change has the potential to provide crucial ecological information on bog responses to environmental factors, peat OM molecular composition has not been addressed in detail. Here, a 568-cm-deep peat sequence was studied at high resolution, by attenuated reflectance Fourier-transform infrared spectroscopy (FTIR-ATR) in the mid-infrared region (4000–400 cm–1). Principal components analysis was performed on selected absorbances and change-point modelling was applied to the records to determine the timing of changes. Four components accounted for peat composition: (i) depletion/accumulation of labile (i.e. carbohydrates) and recalcitrant (i.e. lignin and other aromatics, aliphatics, organic acids and some N compounds) compounds, due to peat decomposition; (ii) variations in N compounds and carbohydrates; (iii) residual variation of lignin and organic acids; and (iv) residual variation of aliphatic structures. Peat decomposition showed two main patterns: a long-term trend highly correlated to peat age (r = 0.87), and a short-term trend, which showed five main phases of increased decomposition (at ~8.4–8.1, ~7.0–5.6, ~3.5–3.1, ~2.7–2.1 and ~1.6–1.3 ka) – mostly corresponding to drier climate and its effect on bog hydrology. The high peat accumulation event (~5.6–3.9 ka), described in earlier studies, is characterized by the lowest degree of peat decomposition of the whole record. Given that FTIR-ATR is a quick, non-destructive, cost-effective technique, our results indicate that it can be applied in a systematic way (including multicore studies) to peat research and provide relevant information on the evolution of peatlands.
  •  
29.
  • Martinez Cortizas, Antonio, et al. (author)
  • Atmospheric Pb pollution in N Iberia during the late Iron Age/Roman times reconstructed using the high-resolution record of La Molina mire (Asturias, Spain)
  • 2013
  • In: Journal of Paleolimnology. - : Springer Science and Business Media LLC. - 0921-2728 .- 1573-0417. ; 50:1, s. 71-86
  • Journal article (peer-reviewed)abstract
    • Extensive mining took place in Spain during the Iron Age and Roman times, although a detailed chronology is still lacking due to the inherent difficulties in dating mining structures. In this study we sampled and analyzed a core from La Molina mire in the Asturias region, northern Spain. Because more than 100 Roman mines have thus far been found within 20 km of the mire, our aim was to shed light on local mining history, which we can then compare to the wider narrative of early mining pollution in Spain. We focus on the section from similar to 500 BC to AD similar to 600, which has a high temporal resolution of 6-15 year per sample. Geochemical analyses included the determination of major, minor and trace lithogenic elements (Si, Al, Fe, Ti, Ga, Rb, Y, Zr, Th) as markers of mineral content of the peat, and trace metals/metalloids (Mn, Cu, Ni, As, Pb) as well stable Pb isotopes, as potential markers of atmospheric metal pollution. The use of principal components analysis enabled the identification of a dominant geogenic component and a secondary pollution component. The earliest pollution signal of the covered period was recorded by similar to 300 BC, coinciding with the late local Iron Age. Average Pb-206/Pb-207 ratios of samples with ages older than this date was 1.204 +/- A 0.002, while all samples with a younger age had a less radiogenic ratio. Based on the metal pollution component four phases were identified: I, similar to 500 to 300 BC; II, similar to 300 to 20 BC; III, similar to 20 BC-AD 480; IV, AD similar to 480 to 600. The lowest isotopic ratio and highest proportion of pollution Pb (Pb-206/Pb-207 ratio of 1.157 and 89 % of total accumulated Pb) was reached at peak Pb production during Roman times (AD similar to 180 to 340), indicating that this was the period of most intense metal contamination in the area over the studied period. It is remarkable that the La Molina record shows a more extended period (two centuries) of active mining in comparison with other areas in Iberia, and a pattern of repeated shifts in Pb pollution of short duration, which is likely related to the local history of exploitation and exhaustion of mines within the area.
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30.
  • Martínez Cortizas, Antonio, et al. (author)
  • Early atmospheric metal pollution provides evidence for Chalcolithic/Bronze Age mining and metallurgy in Southwestern Europe
  • 2016
  • In: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 545-546, s. 398-406
  • Journal article (peer-reviewed)abstract
    • Although archaeological research suggests that mining/metallurgy already started in the Chalcolithic (3rd millennium BC), the earliest atmospheric metal pollution in SW Europe has thus far been dated to similar to 3500-3200 cal. yr. BP in paleo-environmental archives. A low intensity, non-extensive mining/metallurgy and the lack of appropriately located archives may be responsible for this mismatch. We have analysed the older section (>2100 cal. yr. BP) of a peat record from La Molina (Asturias, Spain), a mire located in the proximity (35-100 km) of mines which were exploited in the Chalcolithic/Bronze Age, with the aim of assessing evidence of this early mining/metallurgy. Analyses included the determination of C as a proxy for organic matter content, lithogenic elements (Si, Al, Ti) as markers of mineral matter, and trace metals (Cr, Cu, Zn, Pb) and stable Pb isotopes as tracers of atmospheric metal pollution. From similar to 8000 to similar to 4980 cal. yr. BP the Pb composition is similar to that of the underlying sediments (Pb 15 +/- 4 mu g g(-1); Pb-206/Pb-207 1.204 +/- 0.002). A sustained period of low Pb-206/Pb-207 ratios occurred from similar to 4980 to similar to 2470 cal. yr. BP, which can be divided into four phases: Chalcolithic (similar to 4980-3700 cal. yr. BP), Pb-206/Pb-207 ratios decline to 1.175 and Pb/Al ratios increase; Early Bronze Age (similar to 3700-3500 cal. yr. BP), Pb-206/Pb-207 increase to 1.192 and metal/Al ratios remain stable; Late Bronze Age (similar to 3500-2800 cal. yr. BP), Pb-206/Pb-207 decline to their lowest values (1.167) while Pb/Al and Zn/Al increase; and Early Iron Age (similar to 2800-2470 cal. yr. BP), Pb-206/Pb-207 increase to 1.186, most metal/Al ratios decrease but Zn/Al shows a peak. At the beginning of the Late Iron Age, Pb-206/Pb-207 ratios and metal enrichments show a rapid return to pre-anthropogenic values. These results provide evidence of regional/local atmospheric metal pollution triggered by the earliest phases of mining/metallurgy in the area, and reconcile paleo-environmental and archaeological records.
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31.
  • Martínez Cortizas, Antonio, et al. (author)
  • Holocene atmospheric dust deposition in NW Spain
  • 2020
  • In: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 30:4, s. 507-518
  • Journal article (peer-reviewed)abstract
    • Atmospheric dust plays an important role in terrestrial and marine ecosystems, particularly those that are nutrient limited. Despite that most dust originates from arid and semi-arid regions, recent research has shown that past dust events may have been involved in boosting productivity in nutrient-poor peatlands. We investigated dust deposition in a mid-latitude, raised bog, which is surrounded by a complex geology (paragneiss/schist, granite, quartzite and granodiorite). As proxies for dust fluxes, we used accumulation rates of trace (Ti, Zr, Rb, Sr and Y) as well as major (K and Ca) lithogenic elements. The oldest, largest dust deposition event occurred between similar to 8.6 and similar to 7.4 ka BP, peaking at similar to 8.1 ka BP (most probably the 8.2 ka BP event). The event had a large impact on the evolution of the mire, which subsequently transitioned from a fen into a raised bog in similar to 1500 years. From similar to 6.7 to similar to 4.0 ka BP, fluxes were very low, coeval with mid-Holocene forest stability and maximum extent. In the late Holocene, after similar to 4.0 ka BP, dust events became more prevalent with relatively major deposition at similar to 3.2-2.5, similar to 1.4 ka BP and similar to 0.35-0.05 ka BP, and minor peaks at similar to 4.0-3.7, similar to 1.7, similar to 1.10-0.95 ka BP and similar to 0.74-0.58 ka BP. Strontium fluxes display a similar pattern between similar to 11 and similar to 6.7 ka BP but then became decoupled from the other elements from the mid Holocene onwards. This seems to be a specific signal of the granodiorite batholith, which has an Sr anomaly. The reconstructed variations in dust fluxes bear a strong climatic imprint, probably related to storminess controlled by North Atlantic Oscillation conditions. Complex interactions also arise because of increased pressure from human activities.
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32.
  • Martínez Cortizas, Antonio, et al. (author)
  • Investigating the Mineral Composition of Peat by Combining FTIR-ATR and Multivariate Analysis
  • 2021
  • In: Minerals. - : MDPI AG. - 2075-163X. ; 11:10
  • Journal article (peer-reviewed)abstract
    • The mineral content of peat has received little attention until the last few decades, when peat cores have been increasingly used to study past dust deposition. Paleodust deposition is commonly reconstructed through elemental datasets, which are used to infer deposition rates, storminess patterns, mineral composition, source identification, and fertilization effects. To date, only a few studies have directly analyzed the mineralogy (by XRD and SEM) and particle size of peat mineral matter, and the conducted studies have usually been constrained by the need to remove a large amount of organic matter, which risks altering the mineral component. One alternative is to use quick, nondestructive techniques, such as FTIR-ATR, that require little sample preparation. In this study, we analyzed by FTIR-ATR both the bulk peat and ash fractions of a sequence taken in a minerogenic mire that covered a wide inorganic matter content range (6%–57%). Aided by principal component analysis on transposed IR spectral data, we were able to identify the main minerals in bulk peat and ash, quartz, mica (likely muscovite), K feldspar (likely microcline), and plagioclase (likely anorthite), which are consistent with the local geology of the mire catchment. Changes in mineral composition during the last ca. 2800 years were coeval with previously reconstructed environmental changes using the same core. Our results suggest that FTIR-ATR has great potential to investigate peat mineral matter and the processes that drive its compositional change.
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33.
  • Martínez Cortizas, Antonio, et al. (author)
  • Linking structural and compositional changes in archaeological human bone collagen : an FTIR-ATR approach
  • 2020
  • In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10:1
  • Journal article (peer-reviewed)abstract
    • Collagen is the main structural and most abundant protein in the human body, and it is routinely extracted and analysed in scientific archaeology. Its degree of preservation is, therefore, crucial and several approaches are used to determine it. Spectroscopic techniques provide a cost-effective, non-destructive method to investigate the molecular structure, especially when combined with multivariate statistics (chemometric approach). In this study, we used FTIR-ATR spectroscopy to characterise collagen extracted from skeletons recovered from necropoleis in NW Spain spanning from the Bronze Age to eighteenth century AD. Principal components analysis was performed on a selection of bands and structural equation models (SEM) were developed to relate the collagen quality indicators to collagen structural change. Four principal components represented: (i) Cp1, transformations of the backbone protein with a residual increase in proteoglycans; (ii) Cp2, protein transformations not accompanied by changes in proteoglycans abundance; (iii) Cp3, variations in aliphatic side chains and (iv) Cp4, absorption of the OH of carbohydrates and amide. Highly explanatory SEM models were obtained for the traditional collagen quality indicators (collagen yield, C, N, C:N), but no relationship was found between quality and delta C-13 and delta N-15 ratios. The observed decrease in C and N content and increase in C:N ratios is controlled by the degradation of protein backbone components and the relative preservation of carbon-rich compounds, proteoglycans and, to a lesser extent, aliphatic moieties. Our results suggest that FTIR-ATR is an ideal technique for collagen characterization/pre-screening for palaeodiet, mobility and radiocarbon research.
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34.
  • Martínez Cortizas, Antonio, et al. (author)
  • Structural equation modeling of long-term controls on mercury and bromine accumulation in Pinheiro mire (Minas Gerais, Brazil)
  • 2021
  • In: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 757
  • Journal article (peer-reviewed)abstract
    • The application of statistical modeling is still infrequent in mercury research in peat, despite the ongoing debate on the weight of the diverse factors (climate, peat decomposition, vegetation changes, etc.) that may affect mercury accumulation. One of the few exceptions is the Hg record of Pinheiro mire (souheast Brazil). Previous studies on this mire modeled mercury using principal components regression and partial least squares. These methods assume independence between factors, which is seldom the case in natural systems, thus hampering the identification of mediating effects and interactions. To overcome these limitations, in this reserach we use structural equation modeling (PLS-SEM) to model mercury and bromine peat records - bromine has been used in some investigations to normalize mercury accumuation. The mercury model explained 83% of the variance and suggested a complex control: increased peat decomposition, dust deposition and humid dimates enhanced mercury accumulation, while increased mineral fluxes resulted in a decrease in mercury accumulation. The bromine model explained 90% of the variation in concentrations: increased dust deposition and peat decomposition promoted bromine accumulation, while time (i.e. peat age) promoted bromine depletion. Thus, although mercury and bromine are both organically bound elements with relevant atmospheric cycles the weights of the factors involved in their accumulation differed significantly. Our results suggest caution when using bromine to normalize mercury accumulation. PLS-SEM results indicate a large time dependence of peat decomposition, catchment mineral fluxes, long-term climate change, and atmospheric deposition: while atmospheric dust, mineral fluxes and peat decomposition showed high to moderate climate dependency. In particular, they also point to a relevant role of autogenic processes (i.e. the build up and expansion of the mire within the catchment), which controlled local mineral fluxes; an aspect that has seldom been considered.
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35.
  • Mighall, Tim M., et al. (author)
  • Climate Change, Fire and Human Activity Drive Vegetation Change during the Last Eight Millennia in the Xistral Mountains of NW Iberia
  • 2023
  • In: Quaternary. - : MDPI AG. - 2571-550X. ; 6:1
  • Journal article (peer-reviewed)abstract
    • An 8500-year record of high-resolution pollen, non-pollen palynomorph, microscopic charcoal and selected geochemical data (Ti, Zr and Pb) is presented from an ombrotrophic mire from the Xistral Mountains, Galicia, North-West Iberia. The results suggest that vegetation changes over the last eight millennia are primarily the result of human disturbance, fire and climate change. Climate and fire were the main factors influencing vegetation development during the early to mid-Holocene, including a short-lived decline in forest cover c. 8.2 cal. ka BP. Changes associated with the 4.2 and 2.8 cal. Ka BP events are less well defined. Human impact on vegetation became more pronounced by the late Holocene with major periods of forest disturbance from c. 3.1 cal. ka BP onwards: during the end of Metal Ages, Roman period and culminating in the permanent decline of deciduous forests in the post-Roman period, as agriculture and metallurgy intensified, leading to the creation of a cultural landscape. Climate change appears to become less influential as human activity dominates during the Late Holocene.
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36.
  • Muller, Joanne, et al. (author)
  • Possible evidence for wet Heinrich phases in tropical NE Australia: The Lynch's Crater deposit
  • 2008
  • In: Quaternary Science Reviews. ; 27, s. 468-475
  • Journal article (peer-reviewed)abstract
    • Unarguably, one of the most significant paleoclimatological discoveries of the last two decades has been that of abrupt climate events (Dansgaard-Oeschger cycles and Heinrich events). Most evidence for these events has originated from the high-latitude Northern Hemisphere, with few records documenting the response of the low latitude Southern Hemisphere. Here we present new data from Lynch's Crater, a unique terrestrial record from NE-Australia that may show evidence for southward propagations of the Intertropical Convergence Zone (ITCZ) during abrupt climate perturbations as a result of alteration of the low latitude air masses. Proxies for precipitation/wetness indicate enhanced rainfall in the region during Heinrich events (H events 1-3) and the 8.2 ka Northern Hemisphere cold event. A fully coupled atmosphere/ocean climate model simulating a 1 Sv freshwater influx to the North Atlantic Ocean produces a scenario which agrees with the climate changes shown by the Lynch's Crater record. The model shows precipitation anomalies that include a southward migration of the ITCZ and a zonal shift in mid-latitude storm tracks over the Southern Hemisphere equatorial region. These data indicate large-scale shifts of the austral summer ITCZ position that is known to control monsoonal precipitation in NE Australia. This terrestrial record from Australia may demonstrate the involvement of the tropical western Pacific Ocean in ITCZ migrations during abrupt climate events of the last glacial period. Defining such past migrations offers insight into the importance and role of the equatorial region in global climate dynamics.
  •  
37.
  • Muller, Joanne, et al. (author)
  • The use of principle component analyses in characterising trace and major elemental distribution in a 55 kyr peat deposit in tropical Australia: Implications to paleoclimate
  • 2008
  • In: Geochimicia et Cosmochimica Acta. ; 72, s. 449-463
  • Journal article (peer-reviewed)abstract
    • The Lynch's Crater peat deposit in NE-Australia is a sensitive environmental archive located in the tropical Southern Hemisphere. This unique deposit illustrates that local and regional changes had a profound effect on the local Australian ecosystem over the past 55 kyr. To obtain a proxy of past climate changes, trace and major element geochemistry analyses were applied to a 13 m peat core from the crater. Principle component analysis (PCA) was used to identify the main factors that control elemental distribution in the peat and to add interpretative strength to the geochemical behavior of selected major and trace elements. For example, Sc, Al, Cu, and Pb were found to be related to increased erosion of the basin soils, and from this, several periods of significant flux from atmospheric input and/or terrigenous run-off were identified. Geochemically mobile elements during rock weathering and pedogenesis, such as Mg, Ca, and Sr helped to identify the peat ombrotrophic-minerotrophic boundary at ~1.5 m depth and offered important information about fluxes of these nutrients to the mire and their dynamics within the deposit. Arsenic and V comparisons between the peat record (high concentrations in some peat sections) and in local basin rocks (very low concentrations), suggested the presence of a long range, atmospheric dust source early in the formation of the mire. The Lynch's Crater peat record presents a continuous record of environmental change in tropical Australia and contributes new understanding to geochemical processes in peatlands.
  •  
38.
  • Ninnes, Sofia, 1984-, et al. (author)
  • Application of mid-infrared spectroscopy for the quantitative and qualitative analysis of organic matter in Holocene sediment records
  • 2024
  • In: The Holocene. - : Sage Publications. - 0959-6836 .- 1477-0911. ; 34:3, s. 259-273
  • Journal article (peer-reviewed)abstract
    • The organic matter composition of lake sediments influences important in-lake biogeochemical processes and stores information on environmental changes. Extracting this information is notoriously difficult because of the complexity of the organic matter matrix, which routinely imposes trade-offs between high temporal and analytical detail in the selection of methods of analysis. Here, we demonstrate the potential of diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) for achieving both of these objectives using untreated bulk samples from two Holocene lake-sediment cores from central Sweden. We develop quantitative models for sediment total organic carbon (TOC) with the same predictive abilities as models based on samples diluted with KBr and qualitatively characterize the organic matter using a spectra processing-pipeline combined with principal component analysis. In the qualitative analysis we identified four organic matter sub-fractions and the interpretation of these is supported and further advanced with molecular data from pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Within these organic fractions, compound groups such as aromatics, lignin, aliphatics, proteins and polysaccharides were identified by means of DRIFTS and the analyses and processes outlined here enables rapid and detailed quantitative and qualitative analysis of sediment organic matter. The DRIFTS approach can be used as stand-alone method for OM characterization with high temporal resolution in Holocene sediment records. It may also function as a screening process for more specific analyses of sample subsets, such as when coupled with pyrolysis-GC/MS to further tease apart the OM composition, identify sources and determine degradation status.
  •  
39.
  • Olid, Carolina, et al. (author)
  • Improving the Pb-210-chronology of Pb deposition in peat cores from Chao de Lamoso (NW Spain)
  • 2013
  • In: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 443, s. 597-607
  • Journal article (peer-reviewed)abstract
    • The natural radionuclide Pb-210 is commonly used to establish accurate and precise chronologies for the recent (past 100-150 years) layers of peat deposits. The most widely used Pb-210-dating model, Constant Rate of Supply (CRS), was applied using data from three peat cores from Chao de Lamoso, an ombrotrophic mire in Galicia (NW Spain). On the basis of the CRS-chronologies, maximum Pb concentrations and enrichment factors (EFs) occurred in the 1960s and late 1970s, consistent with the historical use of Pb. However, maximum Pb fluxes were dated in the 1940s and the late 1960s, 10 to 20 years earlier. Principal component analysis (PCA) showed that, although the Pb-210 distribution was mainly (74%) controlled by radioactive decay, about 20% of the Pb-210 flux variability was associated with atmospheric metal pollution, suggesting an extra Pb-210 supply source and thus invalidating the main assumption of the CRS model. When the CRS-ages were recalculated after correcting for the extra input from the Pb-210 inventory of the uppermost peat layers of each core, Pb flux variations were consistent with the historical atmospheric Pb deposition. Our results not only show the robustness of the CRS model to establish accurate chronologies of recent peat deposits but also provide evidence that there are confounding factors that might influence the calculation of reliable peat accumulation rates (and thus also element accumulation rates/fluxes). This study emphasizes the need to verify the hypotheses of Pb-210-dating models and the usefulness of a full geochemical interpretation of peat bog records.
  •  
40.
  • Olid, Carolina, et al. (author)
  • Modeling the downward transport of Pb-210 in Peatlands : Initial Penetration-Constant Rate of Supply (IP-CRS) model
  • 2016
  • In: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 541, s. 1222-1231
  • Journal article (peer-reviewed)abstract
    • The vertical distribution of 210Pb is commonly used to date peat deposits accumulated over the last 100-150 years. However, several studies have questioned this method because of an apparent post-depositional mobility of 210Pb within somepeat profiles. In this study, we introduce the Initial Penetration-Constant Rate of Supply (IP-CRS) model for calculating ages derived from 210Pb profiles that are altered by an initial migration of the radio-nuclide. This new, two-phased, model describes the distribution of atmospheric-derived 210Pb (210Pbxs) in peat taking into account both incorporation of 210Pb into the accumulating peat matrix as well as an initial flushing of 210Pb through the uppermost peat layers. The validity of the IP-CRS model is tested in four anomalous 210Pb peat records that showed some deviations from the typical exponential decay profile not explained by variations in peat accumulation rates. Unlike the most commonly used210Pb-dating model (Constant Rate of Supply (CRS)), the IP-CRS model estimates peat accumulation rates consistent with typical growth rates for peatlands from the same areas. Confidence in the IP-CRS chronology is also provided by the good agreement with independent chronological markers (i.e. 241Am and 137Cs). Our results showed that the IP-CRS can provide chronologies from peat records where 210Pb mobility is evident, being a valuable tool for studies reconstructing past environmental changes using peat archives during the Anthropocene.
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41.
  • Pérez-Rodríguez, Marta, et al. (author)
  • Industrial-era lead and mercury contamination in southern Greenland implicates North American sources
  • 2018
  • In: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 613, s. 919-930
  • Journal article (peer-reviewed)abstract
    • To study the long-range transport of atmospheric pollutants from lower latitude industrial areas to the Arctic, we analysed a peat core spanning the last similar to 700 cal. yr (similar to 1300-2000 CE) from southern Greenland, an area sensitive to atmospheric pollution from North American and Eurasian sources. A previous investigation conducted in the same location recorded atmospheric lead (Pb) pollution after similar to 1845, with peak values recorded in the 1970s, and concluded that a North American source was most likely. To confirm the origin of the lead, we present new Pb isotope data from Sandhavn, together with a high-resolution record for mercury (Hg) deposition. Results demonstrate that the mercury accumulation rate has steadily increased since the beginning of the 19th century, with maximum values of 9.3 mu g m(-2) yr(-1) recorded similar to 1940. Lead isotopic ratios show two mixing lines: one which represents inputs from local and regional geogenic sources, and another that comprises regional geogenic and pollution sources. Detrending the Pb isotopic ratio record (thereby extracting the effect of the geogenic mixing) has enabled us to reconstruct a detailed chronology of metal pollution. The first sustained decrease in Pb isotope signals is recorded as beginning similar to 1740-1780 with the lowest values (indicating the highest pollution signature) dated to similar to 1960-1970. The 206Pb/207Pb ratio of excess Pb (measuring 1.222, and reflecting pollution generated Pb), when compared with the Pb isotopic composition of the Sandhavn peat record since the 19th century and the timing of Pb enrichments, clearly points to the dominance of pollution sources fromNorth America, although it did not prove possible to further differentiate the emissions sources geographically.
  •  
42.
  • Piñeiro-Juncal, Nerea, et al. (author)
  • Review of the physical and chemical properties of seagrass soils
  • 2022
  • In: Geoderma. - : Elsevier BV. - 0016-7061 .- 1872-6259. ; 428
  • Journal article (peer-reviewed)abstract
    • Seagrasses are a polyphyletic group of angiosperms that colonized marine environments more than 30 million years ago and currently inhabit coastal soft and rocky substrates in all continents except Antarctica. Due to their evolution from terrestrial plants, seagrasses have belowground organs that interact with the substrate, transforming it through chemo-physical processes analogous to terrestrial soil formation. Although seagrass substrates provide valuable ecosystem services including carbon and coastal stabilization, they have been largely regarded as sediments by marine scientists and neglected in soil science research. However, over the last decades, the increasing interest in carbon accumulation by seagrasses has generated multiple data on seagrass soil physical and chemical characteristics. Here, we review clay and silt content (<0.063 mm particle size), redox potential, pH, carbonate content, organic carbon or organic matter contents, dry bulk density, porosity and color of seagrass soils worldwide, summarizing data typically used for soil description, and looking for generalities in soil characteristics across seagrass habitats. The data gathered was biased towards temperate species and high-income countries, while data about color, porosity, redox potential and pH was scarce. Soil characteristics did not show significant differences among seagrass bioregions. Most seagrass substrates showed sandy textures, whereas one of the most sampled genera, Posidonia, was not present in muddy substrates. The soil Corg content was significantly higher in meadows formed by persistent species (mean ± SD; 1.76 ± 2.17 %) than in meadows formed by species with opportunistic and colonizing life-strategies (1.52 ± 2.24 and 0.76 ± 0.95 %, respectively), while mud content was significantly higher in meadows formed by opportunistic and colonizing species (27.87 ± 29.58 and 21.23 ± 21.77 %, respectively) than in those formed by persistent species (11.83 ± 14.45 %). Redox potential was significantly lower in intertidal than in subtidal meadows, although caution is needed when interpreting these differences due to methodological limitations. This review provides an overview of current knowledge on seagrass soil characteristics, while identifying knowledge gaps in seagrass soil science, including geographical, species diversity and soil physico-chemical traits that limit our capacity to characterize and classify seagrass soils worldwide.
  •  
43.
  • Rauch, Sebastien, 1971, et al. (author)
  • Anthropogenic Forcings on the Surficial Osmium Cycle
  • 2010
  • In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 44:3, s. 881-887
  • Journal article (peer-reviewed)abstract
    • Osmium is among the least abundant elements in the Earth's continental crust. Recent anthropogenic Os contamination of the environment from mining and smelting activities, automotive catalytic converter use, and hospital discharges has been documented. Here we present evidence for anthropogenic overprinting of the natural Os cycle using a ca. 7000-year record of atmospheric Os deposition and isotopic composition from an ombrotrophic peat bog in NW Spain. Preanthropogenic Os accumulation in this area is 0.10 +/- 0.04 ng m(-2) y(-1). The oldest strata showing human influence correspond to early metal mining and processing on the Iberian Peninsula (ca. 4700-2500 cal. BP). Elevated Os accumulation rates are found thereafter with a local maximum of 1.1 ng m(-2) y(-1) during the Roman occupation of the Iberian Peninsula (ca. 1930 cal. BP)and a further increase starting in 1750 AD with Os accumulation reaching 30 ng m(-2) y(-1) in the most recent samples. Osmium isotopic composition (Os-187/Os-188) indicates that recent elevated Os accumulation results from increased input of unradiogenic Os from industrial and automotive sources as well as from enhanced deposition of radiogenic Os through increased fossil fuel combustion and soil erosion. We posit that the rapid increase in catalyst-equipped vehicles, increased fossil fuel combustion, and changes in land-use make the changes observed in NW Spain globally relevant.
  •  
44.
  • Ryberg, Eleonor E., et al. (author)
  • Postglacial peatland vegetation succession in Store Mosse bog, south-central Sweden : An exploration of factors driving species change
  • 2022
  • In: Boreas. - : Wiley. - 0300-9483 .- 1502-3885. ; 51:3, s. 651-666
  • Journal article (peer-reviewed)abstract
    • Boreal peatlands are facing significant changes in response to a warming climate. Sphagnum mosses are key species in these ecosystems and contribute substantially to carbon sequestration. Understanding the factors driving vegetation changes on longer time scales is therefore of high importance, yet challenging since species changes are typically affected by a range of internal and external processes acting simultaneously within the system. This study presents a high-resolution macrofossil analysis of a peat core from Store Mosse bog (south-central Sweden), dating back to nearly 10 000 cal. a BP. The aim is to identify factors driving species changes on multidecadal to millennial timescales considering internal autogenic, internal biotic and external allogenic processes. A set of independent proxy data was used as a comparison framework to estimate changes in the bog and regional effective humidity, nutrient input and cold periods. We found that Store Mosse largely follows the expected successional pathway for a boreal peatland (i.e. lake -> fen -> bog). However, the system has also been affected by other interlinked factors. Of interest, we note that external nutrient input (originating from dust deposition and climate processes) has had a negative effect on Sphagnum while favouring vascular plants, and increased fire activity (driven by allogenic and autogenic factors) typically caused post-fire, floristic wet shifts. These effects interactively caused a floristic reversal and near disappearance of a once-established Sphagnum community, during which climate acted as an indirect driver. Overall, this study highlights that the factors driving vegetation change within the peatland are multiple and complex. Consideration of the role of interlinked factors on Sphagnum is crucial for an improved understanding of the drivers of species change on short- and long-term scales.
  •  
45.
  • Rydberg, Johan, 1976-, et al. (author)
  • Assessing the stability of mercury and methylmercury in a varved lake sediment deposit
  • 2008
  • In: Environmental Science & Technology. - : American Chemical Society. - 0013-936X .- 1520-5851. ; 42:12, s. 4391-4396
  • Journal article (peer-reviewed)abstract
    • Using lake sediments to infer past total mercury and methylmercury loading to the environment requires that diagenetic processes within the sediment do not significantly affect the concentrations or net accumulation rates of the mercury species. Because carbon is lost during early sediment diagenesis, the close link between carbon and mercury raises the question of how reliable lake sediments are as archives of total mercury and methylmercury loading. In this study we used a series of freeze cores taken in a lake with varved (annually laminated) sediment to assess the stability of total mercury and methylmercury over time. By tracking material deposited in specific years in cores collected in different years, we found that despite a 20–25% loss of carbon in the first 10–15 years, there was no apparent loss of total mercury over time; hence, lake sediments can be considered as reliable archives. However, over the first 5–8 years after sedimentation, about 30–40% of the methylmercury was lost (a decrease of 0.025–0.030 μg MeHg m−2 yr−1), suggesting that sediment profiles showing increasing methylmercury concentrations toward the sediment surface are in large part an artifact of diagenetic processes (net demethylation), rather than a record of changes in methylmercury loading.
  •  
46.
  • Schellekens, Judith, et al. (author)
  • Preferential degradation of polyphenols from Sphagnum-4-Isopropenylphenol as a proxy for past hydrological conditions in Sphagnum-dominated peat
  • 2015
  • In: Geochimica et Cosmochimica Acta. - : Elsevier. - 0016-7037 .- 1872-9533. ; 150, s. 74-89
  • Journal article (peer-reviewed)abstract
    • The net accumulation of remains of Sphagnum spp. is fundamental to the development of many peatlands. The effect of polyphenols from Sphagnum on decomposition processes is frequently cited but has barely been studied. The central area of the Rodmossamyran peatland (Sweden) is an open lawn that consists mostly of Sphagnum spp. with a very low contribution from vascular plants. In order to determine the effects of decay on sphagnum phenols, 53 samples of a 2.7 m deep core from this lawn were analysed with pyrolysis gas chromatography-mass spectrometry (pyrolysis-GC-MS) and compared with more traditional decomposition proxies such as C/N ratio, UV light transmission of alkaline peat extracts, and bulk density. Factor analysis of 72 quantified pyrolysis products suggested that the variation in 4-isopropenylphenol was largely determined by aerobic decomposition instead of Sphagnum abundance. In order to evaluate the effects of aerobic decay in Sphagnum peat, down-core records from different climatic regions were compared using molecular markers for plant biopolymers and C/N ratio. These included markers for lignin from vascular plants ((di) methoxyphenols), polyphenols from Sphagnum spp. (4-isopropenylphenol), and cellulose (levoglucosan). Our results indicate that polyphenols from Sphagnum are preferentially degraded over polysaccharides; consequently the variability of the marker for sphagnum acid, 4-isopropenylphenol, was found indicative of decomposition instead of reflecting the abundance of Sphagnum remains. The fact that 4-isopropenylphenol is aerobically degraded in combination with its specificity for Sphagnum spp. makes it a consistent indicator of past hydrological conditions in Sphagnum-dominated peat. In contrast, the variability of C/N records in Sphagnum-dominated peat was influenced by both vegetation shifts and decomposition, and the dominant effect differed between the studied peatlands. Our results provide direction for modelling studies that try to predict possible feedback mechanisms between peatlands and future climate change, and indicate that the focus in Sphagnum decay studies should be on carbohydrates rather than on phenolic compounds.
  •  
47.
  • Sjöström, Jenny K., et al. (author)
  • Holocene storminess dynamics in northwestern Ireland : shifts in storm duration and frequency between the mid- and late Holocene
  • 2024
  • In: Quaternary Science Reviews. - : Elsevier. - 0277-3791 .- 1873-457X. ; 337
  • Journal article (peer-reviewed)abstract
    • Substantial uncertainties exist regarding how future climate change will affect storminess (storm frequency and intensity) in Ireland and the United Kingdom (UK). Knowledge about spatiotemporal variations of past storminess gives us a better understanding of its mechanisms on centennial to millennial time scales, as well as the impact of external forcing on future storminess in climate models. Here, we present the oldest storm record to date from Ireland, covering the last 8000 years, reconstructed from the Roycarter Bog, a coastal blanket bog in north-western Ireland. The sequence was analysed for grain-size, chemical, mineral and organic molecular composition. The chronology was built on 11 AMS radiocarbon dates. The deposit characteristics, location and low inorganic content suggest aeolian transport of particles to the bog throughout the studied period. Cluster analysis of the grain-size frequency curves, along with the coarse to fine sand ratio, allowed the identification of eleven storm periods (cal yr BP): 6150–5500 (1); 4970–4130 (2); 4000 (3); 3490–3290 (4); 3230 (5); 2850–2590 (6); 2170–1920 (7); 1440 (8); 1225–890 (9); 620–470 (10); and 290–230 (11).During the mid-Holocene, the relative sea level was lower and the local beach sources located further away, giving a longer transport distance compared to the late Holocene. In the latter part of the mid-Holocene (6150–4130 cal yr BP), during the Holocene thermal maximum, increased storminess and wind strengths were inferred for north-western Ireland, manifested as two longer storm periods. During the late Holocene the storm frequency increased, and a greater number (9) of shorter storm periods were recorded. Comparison between our results and regional peat palaeostorm records from Scotland, north of our study site, showed an antiphase relationship between storminess in Ireland and Scotland during the latter part of the mid-Holocene, but mostly in-phase storminess over the last 3000 years. Taken together, enhanced wind strength and storminess were recorded during the warmer mid-Holocene, while an increased frequency of storm events occurred in the cooler late Holocene. Mid-Holocene storm periods occurred during locally wet periods, while most of the storm periods during late Holocene occurred during drier phases. Alternatively, the elevated mineral input during late Holocene promoted microbial activity and peat decomposition. The apparent variability in cyclicity and frequency between the mid- and late Holocene indicates that the processes governing storminess in the region shifted. This calls for further studies ahead, including climate modelling, to disentangle the complex processes governing storminess on millennial to centennial time scale.
  •  
48.
  • Sjöström, Jenny K., et al. (author)
  • Paleodust deposition and peat accumulation rates : bog size matters
  • 2020
  • In: Chemical Geology. - : Elsevier. - 0009-2541 .- 1872-6836. ; 554
  • Journal article (peer-reviewed)abstract
    • We present a high-resolution peat paleodust and accumulation rate record spanning the last 8300 years from Draftinge Mosse (400 ha), southern Sweden (57 degrees 06'27.6 '' N 13 degrees 42'54.1 '' E). The record was analysed for peat accumulation rates (PAR), elemental concentrations, mineralogy, and plant macrofossil content. Five periods of increased mineral deposition were recorded. The first event occurred between similar to 6280 and similar to 5570 cal BP, during the fen to bog transition. This is followed by four atmospheric mineral dust events (DE) which were recorded in the ombrotrophic section of the sequence at (cal BP): similar to 2200; similar to 1385-1150; similar to 830-590, and from similar to 420 to the present. Statistical analysis and elemental ratios indicated that both the mineralogy and grain size shifted when the system transitioned from fen into bog, showing that the governing transport process shifted with the peat-land succession stages. This highlights the importance of identifying peatland succession stages within peat paleodust studies. Following all four DE, increases in PAR were observed, implying a coupling to dust deposition. Comparison of DE and PAR with a paleodust record from Store Mosse, a 20 times larger bog located ca 18 km away (Kylander et al. 2016), showed that both PAR and dust deposition are largely represented by single-core reconstructions, indicating that they are driven by a common climate forcing mechanism. However, higher PAR and dust deposition rates were observed in the more moderately sized Draftinge Mosse, suggesting that the size of the bog is important to consider in peat paleodust studies. Furthermore, the smaller bog responded more rapidly to hydrological changes, indicating that the size of the bog affects its' buffering capacity. Authigenic carbonates, observed here during episodes of rapid peat growth, coincide with changes in REE ratios, indicating that authigenic peat processes potentially cause REE fractionation.
  •  
49.
  • Sjöström, Jenny, 1978-, et al. (author)
  • Mid-Holocene reconstruction of peat paleodust deposition and accumulation rates in southern Sweden during the last 5400 years : processes and links
  • Other publication (other academic/artistic)abstract
    • We present a peat paleodust and accumulation rates study from Davidsmosse, Halland region, south-west Sweden. The 458 cm peat sequence was studied for peat composition, bulk density, elemental composition and ash content. The results were quantitatively assessed using principal component analysis and related to calendar ages by radiocarbon dating. Local soil and sediments samples from the surrounding area (within 4 km radius) as well as aeolian dunes located closer to the coast (25 km) were analysed for elemental concentrations and mineral content. These results were compared to the minerals on the current bog surface and their similarity suggests that the deposited minerals have a local origin. From the peat paleodust reconstruction fourteen dust events (DE) were recorded (cal BP): 3580–3490; 3280; 3140; 3010–2840; 2740; 2610; 2480; 2340; 2240–2130; 2050; 1890; 1690; 1240; and 960–490. A majority of these events were coupled to increases in peat accumulation rates (13 of 14), indicating a relationship between these two processes. Davidsmosse recorded two longer phases that saw numerous DE with larger inferred grain size between 2800 and 2130 cal BP and a stepwise increase from 1000 towards 490 cal BP. These phases overlap in time with increased storm activity recorded in previous studies, both in nearby bog records as well as from dune records in Denmark, and a coastal bog in Scotland, suggesting storminess as a driver of DE signals at Davidsmosse. These stormier periods are related to colder periods, coupled to extended sea ice south of Iceland and a southward shift in storm tracks. Comparison with peat paleodust records further inland did not register these events, indicating that the location of the bog will affect which type of DE that will be recorded. Those DE found at both coastal and inland sites may represent periods with particularly strong winds, or alternatively, regionally dry phases. Further studies are required to untangle which of these processes are responsible for this pattern, for example by conducting grain size analysis on an event recorded at all three bogs, coupled with high resolution dating. 
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50.
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