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  • 1.
    Basapuram, Laxmi Gayatri Devi
    Linköping University, Department of Thematic Studies, Tema Environmental Change.
    Lake Victoria - Carbon, Nitrogen, Phosphorus and Stable Isotope (δ13C) comparison between lake and catchment sediments2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Lake Victoria situated in East Africa faces an acute problem with eutrophication. Many reasons like agricultural production, industrialization, anthropogenic processes, the introduction of species, and economic activities have caused a stress to the overall well-being of the lake. Excess carbon, nitrogen, and phosphorus drive an increase in productivity which affects eutrophication. Previous studies on sediments and nutrient concentrations in the lake have concluded that nutrient concentrations increase due to release from the catchment. This study focuses on catchment sediments collected from four different sites and compares the results with sediments from two additional sites in the lake. The sediment core from Siaya indicates the highest concentrations of TOC (180 g/kg), TN (13 g/kg) and TP (17000μg/L). It is a rural site and poor agricultural practices such as the burn and slash, use of too many fertilizers, clearance of land, atmospheric deposition and precipitation increase elemental concentrations in the sediments compared to the more urban sites. In the lake sediments, the BILL core had higher concentrations of TP (430g/kg) and TN (16 g/kg) compared to the other site (LV-95) which is located far away from the margins of the lake. This core, however, had high TOC levels (180g/kg). The increase of nutrient levels in lake sediments is thought to be due to non-point sources from the catchment. Analyses of stable carbon isotope were used to infer the different organic matter source in the sediments. Based on the range of values for δ13C vs. C/N it is inferred that aquatic algal production and C4 vascular plants are the dominant sources for the organic matter input. The chemical characterization of catchment and lake sediments provides a qualitative link to nutrient influx and eutrophication in the lake.

  • 2.
    Bastviken, David
    et al.
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Svensson, Teresia
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Sandén, Per
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Kylin, Henrik
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Chlorine cycling and fates of 36Cl in terrestrial environments2013Report (Other academic)
    Abstract [en]

    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 as
    • chlorinated 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.

  • 3.
    Bidleman, Terry
    et al.
    Umeå universitet, Sweden.
    Kucklick, John
    National Institute of Standards and Technology, South Carolina, USA.
    Letcher, Robert
    National Wildlife Research Centre, Canada.
    Jantunen, Liisa
    Environment and Climate Change, Canada.
    Wong, Fiona
    Environment and Climate Change, Canada.
    Kylin, Henrik
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    CONTAMINANTS OF EMERGING CONCERN IN THE ARCTIC: AN ASSESSMENT OF HALOGENATED NATURAL PRODUCTS2016In: Organohalogen Compounds, ISSN 1026-4892, Vol. 78, p. 193-196, article id 8.4010Article in journal (Refereed)
  • 4.
    Das, Supriyo Kumar
    et al.
    Department of Geology and Geochemistry, Stockholm University, Stockholm 10691, Sweden.
    Routh, Joyanto
    Department of Geology and Geochemistry, Stockholm University, Stockholm 10691, Sweden.
    Roychoudhury, Alakendra N.
    Department of Geological Sciences, University of Cape Town, Rondebosch 7700, South Africa.
    Sources and historic changes in polycyclic aromatic hydrocarbon input in a shallow lake, Zeekoevlei, South Africa2008In: Organic Geochemistry, ISSN 0146-6380, E-ISSN 1873-5290, Vol. 39, no 8, p. 1109-1112Article in journal (Refereed)
    Abstract [en]

    We investigated the source, seasonality and historical changes in polycyclic aromatic hydrocarbons (PAHs) in Zeekoevlei, a shallow freshwater lake in South Africa. PAH input follows historical changes in land use pattern and recreational activities in Zeekoevlei since the early 1990s. Because anthropogenic activity in the catchment is low, this has resulted in an overall low PAH concentration in the water column and sediments. PAHs of mainly petrogenic origin dominate.

  • 5.
    Ghosh, Devanita
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Distribution and Biogeochemical Cycling of Arsenic In Grey and Brown Sand Aquifers in the Bengal Delta Plains (India)2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    An elevated level of Arsenic (As) in aquifers from India and Bangladesh affecting the human health has been widely reported since the late 1980s. The thesis aim is to investigate the present status of As contamination and biogeochemical cycling with direct role of diverse indigenous bacterial communities in As cycling in the Bengal Delta Plain (BDP) aquifers in Nadia district, West Bengal (India). The As(III) oxidizing bacterial communities were predominant in grey sand aquifers (GSA), but were characteristically absent in brown sand aquifers (BSA). Rainwater recharge containing inorganic and organic dissolved compounds played an important role in shaping the different groups of bacterial phenotypes. It included thearsenite-oxidizing bacteria as revealed by the aioA and 16S rRNA phylogeny. These bacterial communities in BDP groundwater were assumed to utilize the dissolved and sedimentary organic carbon (DOC and SOC) as the primary carbon source for respiration, and remobilization/immobilization of As involving reductive dissolution of iron oxyhydroxides. Hence, sediment and groundwater of these aquifer waters were characterized for their different inorganic constituents (metals) and organic compound classes. There were notable differences between the groundwater DOC and SOC pools. The only similarity between these carbon pools is presence of petroleum-derived hydrocarbons. The SOC in BSA has good correlation with the clay and silt-rich fraction. Notably, As formed complexes with iron, but not manganese. Biomarker characterization in sediments showed presence of terrigenous inputs along with petroleum-derived hydrocarbons. However, these hydrocarbons were absent in BSA sediments, and so were the arsenite oxidizing bacterial communities. Although DOC in groundwater plays an important role in sustaining the microorganisms, the contrasting character of SOC in BSA and GSA strongly influence the shaping of microbial community structure and biogeochemical cycling of As. This particularly affects the natural ‘safe’ drinking water capacity. Overall, the study gives a new directionfor long-term research on As biogeochemical cycling in the contaminated BDP aquifers.

    List of papers
    1. Arsenic Contamination in Soil and Sediment in India: Sources, Effects, and Remediation
    Open this publication in new window or tab >>Arsenic Contamination in Soil and Sediment in India: Sources, Effects, and Remediation
    2015 (English)In: Current Pollution Reports, ISSN 2198-6592, Vol. 1, no 1, p. 35-46Article in journal (Refereed) Published
    Abstract [en]

    Arsenic contamination is turning out to be a major problem these days with its area coverage and the number of people affected directly or indirectly. Now, the level of the contaminant has spread over the soil and sediments from groundwater and other natural sources. Arsenic poisoning in groundwater events is familiar to the world, but the consequences of soil contamination are still unrevealed to the community, specially the people of contaminated counties. Arsenic is a serious instantaneous concern for the people and other life forms regarding the poisoning through crops and vegetables. Many remediation technologies that mainly include physical, chemical, and a few biological methods have been evolved with time to check its effects. The physical and chemical methods for this purpose are often inefficient and/or very expensive, mainly limited to application in aqueous systems, and produce toxic sludge, which again becomes a matter of concern. But bioremediation relies on the fact that biological organisms have the ability to degrade, detoxify, and even accumulate harmful chemicals and offers attractive perspectives for biomonitoring (via biosensors), treatment of wastewater, and the recycling of polluted soils.

    Place, publisher, year, edition, pages
    Springer, 2015
    National Category
    Environmental Sciences Soil Science Water Engineering Geochemistry Water Treatment Environmental Sciences related to Agriculture and Land-use
    Identifiers
    urn:nbn:se:liu:diva-126596 (URN)10.1007/s40726-015-0004-2 (DOI)
    Available from: 2016-03-31 Created: 2016-03-31 Last updated: 2018-03-23Bibliographically approved
    2. Diversity of arsenite oxidizing bacterial communities in arsenic-rich deltaic aquifers in West Bengal, India
    Open this publication in new window or tab >>Diversity of arsenite oxidizing bacterial communities in arsenic-rich deltaic aquifers in West Bengal, India
    2014 (English)In: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 5, no 602, p. 1-14Article in journal (Refereed) Published
    Abstract [en]

    High arsenic (As) concentration in groundwater has affected human health, particularly in South-East Asia putting millions of people at risk. Biogeochemical cycling of As carried out by different bacterial groups are suggested to control the As fluxes in aquifers. A functional diversity approach in link with As precipitation was adopted to study bacterial community structures and their variation within the As contaminated Bengal Delta Plain (BDP) aquifers of India. Groundwater samples collected from two shallow aquifers in Karimpur II (West Bengal, India), during years 2010 and 2011, were investigated to trace the effects immediately after monsoon period (precipitation) on community structure and diversity of bacterial assemblages with a focus on arsenite oxidizing bacterial phyla for two successive years. The study focused on amplification, clone library generation and sequencing of the arsenite oxidase large sub-unit gene aioA and 16S rRNA marker, with respect to changes in elemental concentrations. New set of primers were designed to amplify the aioA gene as a phylogenetic marker to study taxonomically diverse arsenite oxidizing bacterial groups in these aquifers. The overall narrow distribution of bacterial communities based on aioA and 16S rRNA sequences observed was due to poor nutrient status and anoxic conditions in these As contaminated aquifers. Proteobacteria was the dominant phylum detected, within which Acidoyorax, Hydrogenophaga, Albidiferax, Bosea, and Polymorphum were the major arsenite oxidizing bacterial genera based on the number of clones sequenced. The structure of bacterial assemblages including those of arsenite oxidizing bacteria seems to have been affected by increase in major elemental concentrations (e.g., As, Fe, S, and Si) within two sampling sessions, which was supported by statistical analyses. One of the significant findings of this study is detection of novel lineages of 16S rRNA-like bacterial sequences indicating presence of indigenous bacterial communities BDP wells that can play important role in biogeochemical cycling of elements including As.

    Place, publisher, year, edition, pages
    Frontiers, 2014
    Keywords
    Arsenic; aquifer; arsenite oxidation; aioA gene; phylogeny
    National Category
    Earth and Related Environmental Sciences
    Identifiers
    urn:nbn:se:liu:diva-113200 (URN)10.3389/fmicb.2014.00602 (DOI)000345856200001 ()25484877 (PubMedID)
    Note

    Funding Agencies|Swedish Research Link-Asia Program; Department of Science and Technology (DST), Government of India; DST

    Available from: 2015-01-13 Created: 2015-01-12 Last updated: 2017-12-05
    3. Characterization and microbial utilization of dissolved lipid organic fraction in arsenic impacted aquifers (India)
    Open this publication in new window or tab >>Characterization and microbial utilization of dissolved lipid organic fraction in arsenic impacted aquifers (India)
    2015 (English)In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 527, p. 221-233Article in journal (Refereed) Published
    Abstract [en]

    The coupled role of organic matter (OM) and microbial activity is widely acknowledged in arsenic (As) biogeochemical cycling in sedimentary environments. However, little is known about OM characteristics particularly the dissolved fraction in the Bengal Delta Plain aquifers – one of the worst As impacted regions in the world. Ongoing investigations in As-rich aquifers in Nadia district (West Bengal, India) indicate presence of arsenite As(III) oxidizing bacterial communities in the Grey Sand Aquifers (GSA), but absent in Brown Sand Aquifers (BSA). In this study, we investigate the key differences in dissolved organic carbon (DOC) characteristics and its relationship with differences in elemental concentrations, distribution of biomarkers, and utilization of DOC by in situ microbial communities in BSA and GSA. We demonstrate a new approach using ENVI™ C-18 DSK discs to pre-concentrate DOC from large volumes of water, and further extract the OM and separate it into different lipid fractions using the solid phase extraction technique. The aquifers show marked heterogeneity in terms of their DOC characteristics and elemental profiles irrespective of their grey or brown color. DOC indicates variable inputs of terrestrial derived OM sources, and OM derived from decomposition and/or microbial cellular components. DOC in the aquifers consist of predominantly n-alkanoic acids (∌80%) followed by n-alkanes and n-alcohols. The GSAs indicate high iron (Fe) and manganese (Mn) concentrations, and presence of mature petroleum derived hydrocarbons in DOC. BSA has comparatively lower concentrations of Fe and Mn, and shows absence of mature hydrocarbons in DOC. Experiments in presence of indigenous bacteria from groundwater with DOC lipid extracts as the sole carbon source indicate higher growth in the GSA samples implying preferential use of DOC. The potential availability of DOC in these aquifers can influence the community composition of indigenous heterotrophic microbial flora, which in turn can affect elemental cycles including that of As.

    Keywords
    Arsenic, Aquifers, DOC, Microbes, Aquatic biomarkers
    National Category
    Geochemistry Water Treatment Analytical Chemistry Microbiology Water Engineering Environmental Sciences
    Identifiers
    urn:nbn:se:liu:diva-126597 (URN)10.1016/j.jhydrol.2015.04.051 (DOI)000358629100021 ()
    Available from: 2016-03-31 Created: 2016-03-31 Last updated: 2018-03-19Bibliographically approved
    4. Elemental and biomarker characteristics in a Pleistocene aquifer vulnerable to arsenic contamination in the Bengal Delta Plain, India
    Open this publication in new window or tab >>Elemental and biomarker characteristics in a Pleistocene aquifer vulnerable to arsenic contamination in the Bengal Delta Plain, India
    2015 (English)In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 61, p. 87-98Article in journal (Refereed) Published
    Abstract [en]

    An elevated level of arsenic (As) in the Indo-Gangetic delta plain aquifers has been reported since the 1990s. Organic matter (OM) present in groundwater and aquifer sediments supports the microbial communities in these aquifers. During installation of a drinking water well, 26 sediment intervals of 6 m each were retrieved up till 156 m from a Pleistocene brown sand aquifer (BSA). Grain size distribution, sequential extraction of metals and total extractable lipids were analyzed in each sample. These parameters were statistically correlated in order to establish relationship between the physical vs. inorganic and organic characteristics, and how these properties affected the distribution of As in BSAs. The aquifer sediments consisted of medium to coarse sand except the surface sediments and those at the bottom of the well, which had high clay and slit content. Arsenic (As) concentration in sediments ranged from 2 to 21 mg/kg and indicated a strong correlation with grain size. Arsenic was mostly associated with crystalline oxides and silicate-rich minerals. Arsenic showed significant correlation with Fe in all fractions, and suggests presence of pyrite bound As-bearing minerals in these sediments. The diagnostic sedimentary lipid biomarkers indicated presence of compounds derived from vascular plants and microbial cell wall. This inference was supported by various diagnostic lipid ratios. The biomarkers were abundant in surface and deeper layers, which had high clay and silt content. The BSA sediments indicated preferential preservation of n-alkanes over other functional compounds, which were more reactive and subject to degradation. The thick clay layer at 132-156 m contained visible plant fragments, and OM in this layer indicated preferential preservation of organic carbon most likely due to the absence of specific microbial communities that degraded these compounds and mobilized As. Statistical analyses indicated the influence of selective inorganic and organic components (As, Fe and fatty acids) controlling the co-distribution of various inorganic and organic components in the aquifer.

    Place, publisher, year, edition, pages
    PERGAMON-ELSEVIER SCIENCE LTD, 2015
    National Category
    Earth and Related Environmental Sciences
    Identifiers
    urn:nbn:se:liu:diva-122048 (URN)10.1016/j.apgeochem.2015.05.007 (DOI)000360654200008 ()
    Note

    Funding Agencies|Department of Science and Technology, Government of India; Swedish Research Link-Asia Program [2009-6470]; Linkoping University, Sweden

    Available from: 2015-12-18 Created: 2015-10-19 Last updated: 2017-12-01
  • 6.
    Guillemette, Francois
    et al.
    Uppsala University, Sweden.
    von Wachenfeldt, Eddie
    Uppsala University, Sweden; Swedish University of Agriculture Science, Sweden.
    Kothawala, Dolly N.
    Uppsala University, Sweden.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Tranvik, Lars J.
    Uppsala University, Sweden.
    Preferential sequestration of terrestrial organic matter in boreal lake sediments2017In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 122, no 4, p. 863-874Article in journal (Refereed)
    Abstract [en]

    The molecular composition and origin has recently been demonstrated to play a critical role in the persistence of organic matter in lake water, but it is unclear to what degree chemical attributes and sources may also control settling and burial of organic matter in lake sediments. Here we compared the annual contribution of allochthonous and autochthonous sources to the organic matter settling in the water column and present in the sediments of 12 boreal lakes. We used the fluorescence properties and elemental composition of the organic matter to trace its origin and found a consistent pattern of increasing contribution of terrestrial compounds in the sediments as compared to the settling matter, with an annual average allochthony of similar to 87% and similar to 57%, respectively. Seasonal data revealed a predominance of in-lake-produced compounds sinking in the water column in summer. Yet only a slight concurrent decrease in the contribution of terrestrial C to lake sediments was observed during the same period, and sediment allochthony increased again to high levels in autumn. Our results reveal a preferential preservation of allochthonous matter in the sediments and highlight the role of lakes as sequesters of organic carbon primarily originating from the surrounding landscape.

  • 7.
    Gålfalk, Magnus
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Karlson, Martin
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Centre for Climate Science and Policy Research, CSPR.
    Crill, Patrick
    Stockholm Univ, Sweden.
    Bousquet, Philippe
    LSCE, France.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Technical note: A simple approach for efficient collection of field reference data for calibrating remote sensing mapping of northern wetlands2018In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 15, no 5, p. 1549-1557Article in journal (Refereed)
    Abstract [en]

    The calibration and validation of remote sensing land cover products are highly dependent on accurate field reference data, which are costly and practically challenging to collect. We describe an optical method for collection of field reference data that is a fast, cost-efficient, and robust alternative to field surveys and UAV imaging. A lightweight, waterproof, remote-controlled RGB camera (GoPro HERO4 Silver, GoPro Inc.) was used to take wide-angle images from 3.1 to 4.5 m in altitude using an extendable monopod, as well as representative near-ground (amp;lt; 1 m) images to identify spectral and structural features that correspond to various land covers in present lighting conditions. A semi-automatic classification was made based on six surface types (graminoids, water, shrubs, dry moss, wet moss, and rock). The method enables collection of detailed field reference data, which is critical in many remote sensing applications, such as satellite-based wetland mapping. The method uses common non-expensive equipment, does not require special skills or training, and is facilitated by a step-by-step manual that is included in the Supplement. Over time a global ground cover database can be built that can be used as reference data for studies of non-forested wetlands from satellites such as Sentinel 1 and 2 (10 m pixel size).

  • 8.
    Kylin, Henrik
    et al.
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Bouwman, Henk
    Nort-West Uiversity, South Africa.
    Uptake Mechanisms of Airborne Persistent Organic Pollutants in “Plants” – Understanding the Biological Influence on the Deposition of Pops to Remote Terrestrial Ecosystems2014In: Organohalogen Compounds, ISSN 1026-4892, Vol. 76, p. 1207-1210Article in journal (Refereed)
  • 9.
    Kylin, Henrik
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Research Unit: Environmental Sciences and Management, North-West University, Potchefstroom, South Africa.
    Svensson, Teresia
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Jensen, Sören
    Stockholm University, Sweden.
    Strachan, William
    Environment and Climate Change Canada, Canada.
    Franich, Robert
    Scion Research, New Zealand.
    Bouwman, Hindrik
    North-West University, South Africa.
    The trans-continental distributions of pentachlorophenol and pentachloroanisole in pine needles indicate separate origins2017In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 229, p. 688-695Article in journal (Refereed)
    Abstract [en]

    The production and use of pentachlorophenol (PCP) was recently prohibited/restricted by the Stockholm Convention on persistent organic pollutants (POPs), but environmental data are few and of varying quality. We here present the first extensive dataset of the continent-wide (Eurasia and Canada) occurrence of PCP and its methylation product pentachloroanisole (PCA) in the environment, specifically in pine needles. The highest concentrations of PCP were found close to expected point sources, while PCA chiefly shows a northern and/or coastal distribution not correlating with PCP distribution. Although long-range transport and environmental methylation of PCP or formation from other precursors cannot be excluded, the distribution patterns suggest that such processes may not be the only source of PCA to remote regions and unknown sources should be sought. We suggest that natural sources, e.g., chlorination of organic matter in Boreal forest soils enhanced by chloride deposition from marine sources, should be investigated as a possible partial explanation of the observed distributions. The results show that neither PCA nor total PCP (ΣPCP = PCP + PCA) should be used to approximate the concentrations of PCP; PCP and PCA must be determined and quantified separately to understand their occurrence and fate in the environment. The background work shows that the accumulation of airborne POPs in plants is a complex process. The variations in life cycles and physiological adaptations have to be taken into account when using plants to evaluate the concentrations of POPs in remote areas.

  • 10.
    Routh, Joyanto
    Department of Earth Sciences, University of Roorkee, Roorkee 247667, India.
    Metamorphism and Structural Interpretation of the Zanskar Shear Zone, PJW Himalaya, India1993In: Journal of the Geological Society of India, ISSN 0016-7622, E-ISSN 0974-6889, Vol. 41, no 3, p. 187-198Article in journal (Refereed)
    Abstract [en]

    Herren in 1987, reported normal faults resulted in the telescoping of metamorphic isograds within a 200 meter zone between Sumche Topko to Mulung Topko in the Zanskar Shear Zone NW Himalaya. However petrographic study-of sections obtained from Mulung Topko and surrounding areas (pensila-padarn section) indicate that the rocks belong to the kyanite-sillimanite-starurolite grade only. Extension crenulation cleavage and other shear criteria show an initial NESW movement after which a layer parallel extension occurred and the shear zone developed. Minieralogical assemblage and mapping indicate that the isograds run paralleI to each other before they possibly truncate against the shear zone along the Pensila-Padam section. A probable model has been proposed to explain the features

  • 11.
    Routh, Joyanto
    et al.
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Hugelius, Gustaf
    Stockholm University, Sweden .
    Kuhry, Peter
    Stockholm University, Sweden .
    Filley, Timothy
    Purdue University, IN 47907 USA .
    Kaislahti Tillman, Paivi
    Stockholm University, Sweden .
    Becher, Marina
    Stockholm University, Sweden Umeå University, Sweden .
    Crill, Patrick
    Stockholm University, Sweden .
    Multi-proxy study of soil organic matter dynamics in permafrost peat deposits reveal vulnerability to climate change in the European Russian Arctic2014In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 368, p. 104-117Article in journal (Refereed)
    Abstract [en]

    Soil organic carbon (SOC) in permafrost terrain is vulnerable to climate change. Perennially frozen peat deposits store large amounts of SOC, but we know little about its chemical composition and lability. We used plant macrofossil and biomarker analyses to reconstruct the Holocene paleovegetation and paleoenvironmental changes in two peat plateau profiles from the European Russian Arctic. Peat plateaus are the main stores of permafrost soil C in the region, but during most of the Holocene peats developed as permafrost-free rich fens with woody vegetation, sedges and mosses. Around 2200 cal BP, permafrost aggraded at the site resulting in frost heave and a drastic reduction in peat accumulation under the drier uplifted surface conditions. The permafrost dynamics (aggradation, frost-heave and thaw) ushered changes in plant assemblages and carbon accumulation, and consequently in the biomarker trends too. Detailed biomarker analyses indicate abundant neutral lipids, which follow the general pattern: n-alkanols greater than sterols greater than= n-alkanes greater than= triterpenols. The lignin monomers are not as abundant as the lipids and increase with depth. The selected aliphatic and phenolic compounds are source specific, and they have different degrees of lability, which is useful for tracing the impact of permafrost dynamics (peat accumulation and/or decay associated with thawing). However, common interpretation of biomarker patterns, and perceived hydrological and climate changes, must be applied carefully in permafrost regions. The increased proportion (selective preservation) of n-alkanes and lignin is a robust indicator of cumulative decomposition trajectories, which is mirrored by functional compounds (e. g. n-alkanol, triterpenol, and sterol concentrations) showing opposite trends. The distribution of these compounds follows first order decay kinetics, and concurs with the down core diagenetic changes. In particular, some of the biomarker ratios (e. g. stanol/sterol and higher plant alkane index) seem promising for tracing SOC decomposition despite changes in botanical imprint, and sites spanning across different soil types and locations. Carbon accumulation rate calculated at these sites varies from 18.1 to 31.1 gC m(-2) yr(-1), and its evident selective preservation, molecular complexity of organic compounds, and freezing conditions enhance the long-term stability of SOC. Further, our results suggest that permafrost dynamics strongly impact the more undecomposed SOC that could be rapidly remobilized through ongoing thermokarst expansion.

  • 12.
    Routh, Joyanto
    et al.
    Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843, USA.
    McDonald, Thomas J.
    Department of Civil Engineering, Texas A&M University, College Station, TX 77843, USA.
    Grossman, Ethan L.
    Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843, USA.
    Sedimentary organic matter sources and depositional environment in the Yegua formation (Brazos County, Texas)1999In: Organic Geochemistry, ISSN 0146-6380, E-ISSN 1873-5290, Vol. 30, no 11, p. 1437-1453Article in journal (Refereed)
    Abstract [en]

    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.

  • 13.
    Routh, Joyanto
    et al.
    Department of Geology and Geochemistry, Stockholm University, S 10691 Stockholm, Sweden.
    Meyers, Philip A.
    Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109-1063, USA.
    Gustafsson, Örjan
    Department of Geology and Geochemistry, Stockholm University, S 10691 Stockholm, Sweden.
    Baskaran, Mark
    Department of Geology, Wayne State University, Detroit, Michigan 48202, USA.
    Hallberg, Rolf
    Department of Geology and Geochemistry, Stockholm University, S 10691 Stockholm, Sweden.
    Schï¿œldstrï¿œm, Anna
    Department of Geology and Geochemistry, Stockholm University, S 10691 Stockholm, Sweden.
    Sedimentary geochemical record of humanï¿œinduced environmental changes in the Lake Brunnsviken watershed, Sweden2004In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Limnology and Oceanography, Vol. 49, no 5, p. 1560-1569Article in journal (Refereed)
    Abstract [en]

    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.

  • 14.
    Skelton, Alasdair
    et al.
    Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden.
    Claesson, Lillemor
    Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden.
    Chakrapani, Govinda
    Department of Earth Sciences, Indian Institute of Technology, Roorkee, India.
    Mahanta, Chandan
    Department of Civil Engineering, Indian Institute of Technology, Guwahati, India.
    Routh, Joyanto
    Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden.
    Mörth, Magnus
    Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden.
    Khanna, Param
    Wadia Institute of Himalayan Geology, Dehra Dun, India.
    Coupling Between Seismic Activity and Hydrogeochemistry at the Shillong Plateau, Northeastern India2008In: Pure and Applied Geophysics, ISSN 0033-4553, E-ISSN 1420-9136, Vol. 165, no 1, p. 45-61Article in journal (Refereed)
    Abstract [en]

    Transient hydrogeochemical anomalies were detected in a granite-hosted aquifer, which is located at a depth of 110 m, north of the Shillong Plateau, Assam, India, where groundwater chemistry is mainly buffered by feldspar alteration to kaolinite. Their onsets preceded moderate earthquakes on December 9, 2004 (MW = 5.3) and February 15, 2005 (MW = 5.0), respectively, 206 and 213 km from the aquifer. The ratios [Na+K]/Si, Na/K and [Na+K]/Ca, conductivity, alkalinity and chloride concentration began increasing 3–5 weeks before the MW = 5.3 earthquake. By comparison with field, experimental and theoretical studies, we interpret a transient switchover between source aquifers, which induced an influx of groundwater from a second aquifer, where groundwater chemistry was dominantly buffered by the alteration of feldspar to smectite. This could have occurred in response to fracturing of a hydrological barrier. The ratio Ba/Sr began decreasing 3–6 days before the MW = 5.0 earthquake. We interpret a transient switchover to anorthite dissolution caused by exposure of fresh plagioclase to groundwater interaction. This could have been induced by microfracturing, locally within the main aquifer. By comparison with experimental studies of feldspar dissolution, we interpret that hydrogeochemical recovery was facilitated by groundwater interaction and clay mineralization, which could have been coupled with fracture sealing. The coincidence in timing of these two hydrogeochemical events with the only two MW ≥ 5 earthquakes in the study area argues in favor of cause-and-effect seismic-hydrogeochemical coupling. However, reasons for ambiguity include the lack of similar hydrogeochemical anomalies coupled with smaller seismic events near the monitoring station, the >200 km length scale of inferred seismic-hydrogeochemical coupling, and the potential for far-field effects related to the Great Sumatra–Andaman Islands Earthquake of December 26, 2004.

  • 15.
    Sobek, Sebastian
    et al.
    Uppsala University, Sweden.
    Gudasz, Cristian
    Uppsala University, Sweden; Umeå University, Sweden.
    Koehler, Birgit
    Uppsala University, Sweden.
    Tranvik, Lars J.
    Uppsala University, Sweden.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Morales-Pineda, Maria
    University of Cadiz, Spain.
    Temperature Dependence of Apparent Respiratory Quotients and Oxygen Penetration Depth in Contrasting Lake Sediments2017In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 122, no 11, p. 3076-3087Article in journal (Refereed)
    Abstract [en]

    Lake sediments constitute an important compartment in the carbon cycle of lakes, by burying carbon over geological timescales and by production and emission of greenhouse gases. The degradation of organic carbon (OC) in lake sediments is linked to both temperature and oxygen (O-2), but the interactive nature of this regulation has not been studied in lake sediments in a quantitative way. We present the first systematic investigation of the effects of temperature on the apparent respiratory quotient (RQ, i.e., the molar ratio between carbon dioxide (CO2) production and O-2 consumption) in two contrasting lake sediments. Laboratory incubations of sediment cores of a humic lake and an eutrophic lake across a 1-21 degrees C temperature gradient over 157days revealed that both CO2 production and O-2 consumption were positively, exponentially, and similarly dependent on temperature. The apparent RQ differed significantly between the lake sediments (0.630.26 and 0.990.28 in the humic and the eutrophic lake, respectively; meanSD) and was significantly and positively related to temperature. The O-2 penetration depth into the sediment varied by a factor of 2 over the 1-21 degrees C temperature range and was significantly, negatively, and similarly related to temperature in both lake sediments. Accordingly, increasing temperature may influence the overall extent of OC degradation in lake sediments by limiting O-2 supply to aerobic microbial respiration to the topmost sediment layer, resulting in a concomitant shift to less effective anaerobic degradation pathways. This suggests that temperature may represent a key controlling factor of the OC burial efficiency in lake sediments.

  • 16.
    Ulrich, G. A.
    et al.
    Department of Botany and Microbiology, 770 Van Vleet Oval, University of Oklahoma, Norman, OK 73019-0245, USA.
    Martino, D.
    Department of Oceanography, Texas A&M University, College Station, TX 77843, USA.
    Burger, K.
    Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843, USA.
    Routh, Joyanto
    Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843, USA.
    Grossman, E. L.
    Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843, USA.
    Ammerman, J. W.
    Department of Oceanography, Texas A&M University, College Station, TX 77843, USA.
    Suflita, J. M.
    Department of Botany and Microbiology, 770 Van Vleet Oval, University of Oklahoma, Norman, OK 73019-0245, USA.
    Sulfur Cycling in the Terrestrial Subsurface: Commensal Interactions, Spatial Scales, and Microbial Heterogeneity1998In: Microbial Ecology, ISSN 0095-3628, E-ISSN 1432-184X, Vol. 36, no 2, p. 141-151Article in journal (Refereed)
    Abstract [en]

    Microbiological, geochemical, and isotopic analyses of sediment and water samples from the unconsolidated Yegua formation in east-central Texas were used to assess microbial processes in the terrestrial subsurface. Previous geochemical studies suggested that sulfide oxidation at shallow depths may provide sulfate for sulfate-reducing bacteria (SRB) in deeper aquifer formations. The present study further examines this possibility, and provides a more detailed evaluation of the relationship between microbial activity, lithology, and the geochemical environment on meter-to-millimeter scales. Sediment of varied lithology (sands, silts, clays, lignite) was collected from two boreholes, to depths of 30 m. Our findings suggest that pyrite oxidation strongly influences the geochemical environment in shallow sediments ( 5 m), and produces acidic waters (pH 3.8) that are rich in sulfate (28 mM) and ferrous iron (0.3 mM). Sulfur and iron-oxidizing bacteria are readily detected in shallow sediments; they likely play an indirect role in pyrite oxidation. In consistent fashion, there is a relative paucity of pyrite in shallow sediments and a low 34S/32S-sulfate ratio (0.2ᅵ) (reflecting contributions from 34S-depleted sulfides) in shallow regions. Pyrite oxidation likely provides a sulfate source for both oxic and anoxic aquifers in the region. A variety of assays and direct-imaging techniques of 35S-sulfide production in sediment cores indicates that sulfate reduction occurs in both the oxidizing and reducing portions of the sediment profile, with a high degree of spatial variability. Narrow zones of activity were detected in sands that were juxtaposed to clay or lignite-rich sediments. The fermentation of organic matter in the lignite-rich laminae provides small molecular weight organic acids to support sulfate reduction in neighboring sands. Consequently, sulfur cycling in shallow sediments, and sulfate transport represent important mechanisms for commensal interaction among subsurface microorganisms by providing electron donors for chemoautotrophic bacteria and electron acceptors for SRB. The activity of SRB is linked to the availability of suitable electron donors from spatially distinct zones.

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