| 1. |
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| 2. |
- Routh, Joyanto, 1968-, et al.
(författare)
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Sedimentary geochemical record of humanï¿œinduced environmental changes in the Lake Brunnsviken watershed, Sweden
- 2004
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Ingår i: Limnology and Oceanography. - : John Wiley & Sons. - 0024-3590 .- 1939-5590. ; 49:5, s. 1560-1569
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Tidskriftsartikel (refereegranskat)abstract
- Environmental changes in Lake Brunnsviken, its watershed, and the greater Stockholm region since the middle of the nineteenth century have left interpretable geochemical imprints in the bottom sediments. These human-induced perturbations within the lakeï¿œs watershed included agriculture, urbanization, sewage and industrial disposal, and water column aeration. Smaller d15Ntotal values, high organic carbon mass accumulation rates, low C:N ratios, and larger d13Corg values identify periods of increased nutrient delivery and elevated primary productivity in the lake. C: S ratios that change from high to low trace the transition from an oxic hypolimnion to an anoxic one during the periods of high productivity. Accumulations of redox-sensitive trace elements increase during the anoxic period and are further magnified during a time of industrial waste discharge into the lake. A recent decrease in black carbon concentrations in sediments reflects the conversion from wood and coal to cleaner forms of energy.
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| 3. |
- Routh, Joyanto, 1968-, et al.
(författare)
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Sedimentary organic matter sources and depositional environment in the Yegua formation (Brazos County, Texas)
- 1999
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Ingår i: Organic Geochemistry. - : Elsevier. - 0146-6380 .- 1873-5290. ; 30:11, s. 1437-1453
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Tidskriftsartikel (refereegranskat)abstract
- The complex depositional environment of the Eocene Yegua formation (Brazos County, Texas) can be better understood by integrating organic matter (OM) geochemistry with stratigraphy. Yegua sediments represent parasequences separated by exposure surfaces. Organic petrography and geochemistry (biomarkers, C/N ratios, and carbon isotopes) indicate the presence of both terrestrial and marine OM in transgressive sediments. In contrast, regressive sediments contain only terrestrial OM. These differences relate to contrasting OM sources and depositional styles on the shelf. OM in the sediments is immature and the potential for generating hydrocarbons is poor. The study suggests that organic geochemical data can help in distinguishing transgressive and regressive environments in sedimentary formations.
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| 4. |
- Bidleman, Terry, 1942-, et al.
(författare)
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A review of halogenated natural products in Arctic, Subarctic and Nordic ecosystems
- 2019
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Ingår i: Emerging Contaminants. - : Elsevier. - 2405-6650 .- 2405-6642. ; 5, s. 89-115
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Tidskriftsartikel (refereegranskat)abstract
- Halogenated natural products (HNPs) are organic compounds containing bromine, chlorine, iodine, andrarely fluorine. HNPs comprise many classes of compounds, ranging in complexity from halocarbons tohigher molecular weight compounds, which often contain oxygen and/or nitrogen atoms in addition tohalogens. Many HNPs are biosynthesized by marine bacteria, macroalgae, phytoplankton, tunicates,corals, worms, sponges and other invertebrates. This paper reviews HNPs in Arctic, Subarctic and Nordicecosystems and is based on sections of Chapter 2.16 in the Arctic Monitoring and Assessment Program(AMAP) assessment Chemicals of Emerging Arctic Concern (AMAP, 2017) which deal with the highermolecular weight HNPs. Material is updated and expanded to include more Nordic examples. Much ofthe chapter is devoted to “bromophenolic” HNPs, viz bromophenols (BPs) and transformation productsbromoanisoles (BAs), hydroxylated and methoxylated bromodiphenyl ethers (OH-BDEs, MeO-BDEs) andpolybrominated dibenzo-p-dioxins (PBDDs), since these HNPs are most frequently reported. Othersdiscussed are 2,20-dimethoxy-3,30,5,50-tetrabromobiphenyl (2,20-dimethoxy-BB80), polyhalogenated 10-methyl-1,20-bipyrroles (PMBPs), polyhalogenated 1,10-dimethyl-2,20-bipyrroles (PDBPs), polyhalogenatedN-methylpyrroles (PMPs), polyhalogenated N-methylindoles (PMIs), bromoheptyl- and bromooctylpyrroles, (1R,2S,4R,5R,10E)-2-bromo-1-bromomethyl-1,4-dichloro-5-(20-chloroethenyl)-5-methylcyclohexane (mixed halogenated compound MHC-1), polybrominated hexahydroxanthene derivatives(PBHDs) and polyhalogenated carbazoles (PHCs). Aspects of HNPs covered are physicochemicalproperties, sources and production, transformation processes, concentrations and trends in the physicalenvironment and biota (marine and freshwater). Toxic properties of some HNPs and a discussion of howclimate change might affect HNPs production and distribution are also included. The review concludeswith a summary of research needs to better understand the role of HNPs as “chemicals of emergingArctic concern”.
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| 5. |
- Bidleman, Terry, et al.
(författare)
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Chapter 2: Properties, sources, global fate and transport
- 2013
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Ingår i: Canadian Arctic Contaminants Assessment Report III 2013. - Ottawa : Northern Contaminants Program, Aboriginal Affairs and Northern Development Canada. - 9781100546520 ; , s. 19-146
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Bokkapitel (refereegranskat)abstract
- Part II of the second Canadian Arctic Contaminants Assessment Report (CACAR-II) began with a section on “Physicochemical Properties of Persistent Organic Pollutants”, which identified key physicochemical (pchem) properties, provided the rationale for their measurement or prediction and tabulated literature citations for chemicals that are of concern to the NCP (Bidleman et al. 2003). The section also discussed temperature dependence of pchem properties and their applications to describing partitioning in the physical environment.There is, and will continue to be, emphasis on predictive approaches to screening chemicals for persistence, bioaccumulation and toxic (PB&T)properties, as well as long-range atmospheric transport (LRAT) potential (Brown and Wania 2008, Czub et al. 2008, Fenner et al. 2005, Gouin andWania 2007, Howard and Muir 2010, Klasmeier et al. 2006, Matthies et al. 2009, Muir and Howard 2006). This has created the need for determining pchem properties of new and emerging chemicals of concern.Predicting gas exchange cycles of legacy persistent organic pollutants (POPs) and new and emerging chemicals of concern places a high demand on the accuracy of pchem properties, particularly the air/water partition coefficient, KAW. Hexachlorocyclohexanes (HCHs) in Arctic Ocean surface waters are close to air-water equilibrium, with excursions toward net volatilization or deposition that vary with location and season (Hargrave et al. 1993, Jantunen et al. 2008a, Lohmann et al. 2009, Su et al. 2006, Wong et al. 2011) while hexachlorobenzene (HCB) (Lohmann et al. 2009, Su et al. 2006, Wong et al. 2011) and some current use pesticides (CUPs) (Wong et al. 2011) are undergoing net deposition. The predicted Arctic Contamination Potential (ACP) for persistent organic chemicals is strongly influenced by ice cover due to its effect on air-water gas exchange (Meyer and Wania 2007).Many advances have taken place and numerous papers have been published since CACAR-II, which present new measurements and predictions of pchem properties. This section does not attempt to provide a comprehensive review of the field, or to compile pchem properties from the many studies. The approach taken is to highlight the reports which are most relevant to polar science, particularly in areas of improving reliability of pchem properties for POPs, improving experimental techniques and comparing predictive methods. The section ends with a discussion of polyparameter linear free energy relationships (pp-LFERs), which goes beyond partitioning descriptions based on single pchem properties by taking into account specific chemical interactions that can take place in airsurface and water-surface exchange processes. A detailed list of chemical names and nomenclature are provided in the Glossary.
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| 6. |
- Kylin, Henrik, 1959-, et al.
(författare)
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Pentachlorophenol (PCP) and pentachloroanisole (PCA)
- 2017
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Ingår i: AMAP Assessment 2016. - Oslo : AMAP - Arctic Monitoring and Assessment Programme. - 9788279711049 ; , s. 205-211
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Bokkapitel (refereegranskat)abstract
- Pentachlorophenol (PCP) was first synthesized for use as a fungicide for wood protection in the 1930s. PCP affects most organisms by decoupling oxidative phosphorylation and other crucial biochemical functions (IPCS, 1987; UNEP, 2013e). As a result it has found a wide range of biocidal and pesticidal uses. Due to adverse environmental and health effects, restrictions on the use of PCP were first imposed in the 1970s with total bans in effect in some countries by the 1980s (UNEP, 2013d). As of 2014, PCP was still in use in India, Canada and the USA (UNEP, 2014a). In May 2015, PCP was included in Annex A of the Stockholm Convention: calling for elimination, with a time-limited exemption for impregnation of utility poles and crossarms (UNEP, 2015a).
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| 7. |
- van de Velde, Sebastian J, et al.
(författare)
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Exceptionally high respiration rates in the reactive surface layer of sediments underlying oxygen-deficient bottom waters
- 2023
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Ingår i: Proceedings of the Royal Society. Mathematical, Physical and Engineering Sciences. - : ROYAL SOC. - 1364-5021 .- 1471-2946. ; 479:2275
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Tidskriftsartikel (refereegranskat)abstract
- Organic carbon (OC) burial efficiency, which relates the OC burial rate to respiration in the seafloor, is a critical parameter in the reconstruction of past marine primary productivities. The current accepted theory is that sediments underlying oxygen-deficient (anoxic) bottom waters have low respiration rates and high OC burial efficiencies. By combining novel in situ measurements in anoxic basins with reaction-transport modelling, we demonstrate that sediments underlying anoxic bottom waters have much higher respiration rates than commonly assumed. A major proportion of the carbon respiration is concentrated in the top millimeter—the so-called ‘reactive surface layer’—which is likely a feature in approximately 15% of the coastal seafloor. When re-evaluating previously published data in light of our results, we conclude that the impact of bottom-water anoxia on OC burial efficiencies in marine sediments is small. Consequently, reconstructions of past marine primary productivity in a predominantly anoxic ocean based on OC burial rates might be underestimated by up to an order of magnitude.
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| 8. |
- Routh, Joyanto, et al.
(författare)
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Distribution of arsenic and its mobility in shallow aquifer sediments from Ambikanagar, West Bengal, India
- 2011
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Ingår i: Applied Geochemistry. - : Elsevier. - 0883-2927 .- 1872-9134. ; 26:4, s. 505-515
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Tidskriftsartikel (refereegranskat)abstract
- Sediments from a core retrieved during installation of a shallow drinking water well in Ambikanagar (West Bengal, India) were analyzed for various physical and chemical parameters. The geochemical analyses included: (1) a 4-step sequential extraction scheme to determine the distribution of As between different fractions, (2) As speciation (As(3+) vs. As(5+)), and (3) C, N and S isotopes. The sediments have a low percentage of organic C and N (0.10-0.56% and 0.01-0.05%, respectively). Arsenic concentration is between 2 and 7 mg kg(-1), and it is mainly associated with the residual fraction, less susceptible to chemical weathering. The proportion of As(3+) in these sediments is high and ranges from 24% to 74%. Arsenic in the second fraction (reducible) correlates well with Mn, and in the residual fraction As correlates well with several transition elements. The stable isotope results indicate microbial oxidation of organic matter involving SO(4) reduction. Oxidation of primary sulfide minerals and release of As from reduction of Fe(oxy)hydroxides do not seem important mechanisms in As mobilization. Instead, the dominance of As(3+) and presence of As(5+) reducing microorganisms in this shallow aquifer imply As remobilization involving microbial processes that needs further investigations.
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| 9. |
- Miura, Y., et al.
(författare)
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SOIL MOISTURE MONITORING OF AGRICULTURAL FIELDS IN BURKINA FASO USING DUAL POLARIZED SENTINEL-1A DATA
- 2019
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Ingår i: International Geoscience and Remote Sensing Symposium (IGARSS). - : IEEE. - 9781538691540 ; , s. 7045-7048
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Konferensbidrag (refereegranskat)abstract
- We investigated the correlation between backscatter and soil moisture considering precipitation and crop effects using dual polarized Sentinel-1A data. The analyzed data consist of a time-series of 38 Sentinel-1A GRD images acquired on a 12-days repeat cycle from July 2017 to October 2018 over Sapone in Burkina Faso. We show that the temporal change of backscatter corresponds to the soil moisture content rather than crops.
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| 10. |
- Bastviken, David, et al.
(författare)
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Chlorine cycling and fates of 36Cl in terrestrial environments
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Chlorine-36 (36Cl), a radioisotope of chlorine (Cl) with a half-life of 301,000 years, is present in some types of nuclear waste and is disposed in repositories for radioactive waste. As the release of 36Cl from such repositories to the near surface environment has to be taken into account it is of interest to predict possible fates of 36Cl under various conditions as a part of the safety assessments of repositories for radioactive waste. This report aims to summarize the state of the art knowledge on Cl cycling in terrestrial environments. The view on Cl cycling in terrestrial environments is changing due to recent research and it is clear that the chloride ion (Cl–) is more reactive than previously believed. We group the major findings in three categories below according to the amount of data in support of the findings.From the result presented in this report it is evident that:There is an ubiquitous and extensive natural chlorination of organic matter in terrestrial ecosystems.The abundance of naturally formed chlorinated organic compounds (Clorg) frequently exceeds the abundance of Cl–, particularly in soils. Thereby Clorg in many cases dominates the total Cl pool.This has important implications for Cl transport. When reaching surface soils Cl– will not be a suitable tracer of water and will instead enter other Cl pools (Clorg and biomass) that prolong residence times in the system.Cl– dominates import and export from terrestrial ecosystems while Clorg and biomass Cl can dominate the standing stock Cl within terrestrial ecosystems.Both Cl and Clorg pools have to be considered separately in future monitoring programs addressing Cl cycling.Further, there are also indications (in need of confirmation by additional studies) that:There is a rapid and large uptake of Cl– by organisms and an accumulation in green plant parts. A surprisingly large proportion of total catchment Cl (up to 60%) can be found in the terrestrial biomass.Emissions of total volatile organohalogens could be a significant export pathway of Cl from the systems.Some of the Clorg may be very persistent and resist degradation better than average organic matter. This may lead to selective preservation of some Clorg (with associated low bioavailability).There is a production of Clorg in tissues of e.g. plants and animals and Cl can accumulate aschlorinated fatty acids in organisms.Most other nevertheless important aspects are largely unknown due to lack of data. Key unknowns include:The development over time of major Cl pools and fluxes. As long as such data is lacking we cannot assess net changes over time.How the precesses behind chlorination, dechlorination and transport patterns in terrestrial systems are regulated and affected by environmental factors.The ecological roles of the chlorine cycling in general.The ecological role of the microbial chlorination in particular.The chlorine cycling in aquatic environments – including Cl– and Clorg pools in sediment and water, are largely missing.Given the limited present information available, and particularly the lack of data with a temporal dimension and the lack of process understanding, predictive models are challenging. We also summarize currently available methods to study Cl in the environment.
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