| 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.
|
|
| 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.
|
|
| 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.
|
|
| 4. |
- 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.
|
|
| 5. |
- Hernández-Alvarez, María Isabel, et al.
(author)
-
Deficient Endoplasmic Reticulum-Mitochondrial Phosphatidylserine Transfer Causes Liver Disease
- 2019
-
In: Cell. - : Cell Press. - 0092-8674 .- 1097-4172. ; 177:4, s. 881-895.e17
-
Journal article (peer-reviewed)abstract
- Non-alcoholic fatty liver is the most common liver disease worldwide. Here, we show that the mitochondrial protein mitofusin 2 (Mfn2) protects against liver disease. Reduced Mfn2 expression was detected in liver biopsies from patients with non-alcoholic steatohepatitis (NASH). Moreover, reduced Mfn2 levels were detected in mouse models of steatosis or NASH, and its re-expression in a NASH mouse model ameliorated the disease. Liver-specific ablation of Mfn2 in mice provoked inflammation, triglyceride accumulation, fibrosis, and liver cancer. We demonstrate that Mfn2 binds phosphatidylserine (PS) and can specifically extract PS into membrane domains, favoring PS transfer to mitochondria and mitochondrial phosphatidylethanolamine (PE) synthesis. Consequently, hepatic Mfn2 deficiency reduces PS transfer and phospholipid synthesis, leading to endoplasmic reticulum (ER) stress and the development of a NASH-like phenotype and liver cancer. Ablation of Mfn2 in liver reveals that disruption of ER-mitochondrial PS transfer is a new mechanism involved in the development of liver disease.
|
|
| 6. |
- 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.
|
|
| 7. |
- 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.
|
|
