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  • 1.
    Aftab, A.
    et al.
    Petroleum and Natural Gas Engineering Department, Mehran UETSZAB Sindh, Pakistan; Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, Malaysia.
    Ismail, A. R.
    Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, Malaysia.
    Khokhar, S.
    Quaid-e-Awam University of Engineering, Science and Technology, Sindh Pakistan.
    Ibupoto, Zafar Hussain
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering. Institute of Chemistry, University of Sindh Jamshoro, Sindh Pakistan.
    Novel zinc oxide nanoparticles deposited acrylamide composite used for enhancing the performance of water-based drilling fluids at elevated temperature conditions2016In: Journal of Petroleum Science and Engineering, ISSN 0920-4105, E-ISSN 1873-4715, Vol. 146, p. 1142-1157Article in journal (Refereed)
    Abstract [en]

    Multifunctional nano-micron composite compared to single nano-sphere materials revealed wide applications to enhance the physical and chemical stability of base fluids. Therefore, it can be a possible solution for the improvement of the rheological properties and shale inhibition characteristics of conventional water-based drilling fluid (WBDF). The primary goal of the study was to investigate the effects zinc oxide nanoparticles-acrylamide composite termed as ZnO-Am composite over rheological and shale swelling behavior of conventional WBDF. Herein, ZnO-Am composite was synthesized and successfully characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermalgravimeteric analysis (TGA), scanning electron microscope (SEM) and field emission electron microscope (FESEM). Results revealed that the rheological properties such as 10-min gel strength (10-min GS), apparent viscosity (AV), and plastic vicscocity (PV) were slightly increased and obtained within operating range at 150 degrees F by adding the synthesized composite in conventional WBDF. Lubricity was improved by 25% at 150 degrees F. API filtrate loss volume was reduced by 14%. Elevated temperature and pressure (ETP) filtrate loss volume (500 psi, 250 degrees F) was slightly minimized. Shale swelling was merely reduced from 16% to 9%. These findings will contribute to enhance the oil and gas well drilling operations.

  • 2.
    Baker, Andrea
    et al.
    University of Stellenbosch, South Africa.
    Pedentchouk, Nikolai
    University of East Anglia, England.
    Routh, Joyanto
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Roychoudhury, Alakendra N.
    University of Stellenbosch, South Africa.
    Climatic variability in Mfabeni peatlands (South Africa) since the late Pleistocene2017In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 160, p. 57-66Article in journal (Refereed)
    Abstract [en]

    It has been postulated that a bipolar seesaw interhemispheric mechanism dominated the relationship between the Northern and Southern hemisphere climates since the late Pleistocene. A key test for this proposition would be to undertake palaeoenvironmental studies on terrestrial archives in climatically sensitive regions. Southern Africas contemporary C-3 and C-4 terrestrial plant distributions display a definitive geographical pattern dictated by different growing season rainfall and temperature zones; however, the region is generally archive poor due to its overall semi-arid climate and high relief topography. The Mfabeni peatland, with a basal age of c. 47 k yrs calibrated before present (kcal yr BP), is one of the oldest continuous coastal peat deposits in Southern Africa. Molecular leaf wax isotopes (delta C-13(wax)) were generated for a 810 cm long core, and combined with previously published bulk geochemical (delta C-13(bulk), %TOC), palynological, and stratigraphic data, to reconstruct the late Pleistocene and Holocene palaeoenvironments. We interpreted environmental shifts associated with the Heinrich 4, Last Glacial Maximum, deglacial and Holocene periods, which are consistent with adjacent Indian Ocean sea surface temperature records. However, the other shorter climate perturbations during the Heinrich 5, 3, 2, 1, Antarctic cold reversal and Younger Dryas, were muted, most likely due to local hydrological overprinting on the Mfabeni record. A general anti-phase sequence was observed between the Mfabeni record and better established Northern Hemisphere events, underpinning the bipolar seesaw interhemispheric mechanism proposed for global climate forcing since the Late Pleistocene. (C) 2017 Elsevier Ltd. All rights reserved.

  • 3.
    Baker, Andrea
    et al.
    Stellenbosch Univ, South Africa.
    Routh, Joyanto
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Roychoudhury, Alakendra N.
    Stellenbosch Univ, South Africa.
    n-Alkan-2-one biomarkers as a proxy for palaeoclimate reconstruction in the Mfabeni fen, South Africa2018In: Organic Geochemistry, ISSN 0146-6380, E-ISSN 1873-5290, Vol. 120, p. 75-85Article in journal (Refereed)
    Abstract [en]

    The sub-tropical Mfabeni fen is the only continuous coastal peat deposit that documents glacial and interglacial palaeoenvironmental conditions since the late Pleistocene (ca. 47 cal kyr BP) in southern Africa. Published bulk geochemical, biomarker and leaf wax delta C-13 data, along with palynology and stratigraphic studies of the Mfabeni peat sequence, render it an ideal record for testing new palaeoreconstruction proxies. In this study, we aimed to establish the proxy potential of n-alkan-2-one (n-ket) compounds by tracing their source/origin and post-depositional diagenetic change, and if they preserve or not a robust palaeoenvironment signal that complements our understanding of palaeoclimatic variations. In the Mfabeni archive the most likely source for n-kets is via microbial decarboxylation of n + 1-alkanoic acids (n-FAs) and, to a lesser degree, oxidation of same chain length n-alkanes (n-alks). The n-ket average chain length (ACL(ket)) and n-C-23 and C(25)ket/precursor ratios displayed a statistical significant negative relationship with the n-alk aquatic plant proxy (P-aq), suggesting the source of n-kets to be submerged aquatic plants during waterlogged conditions that suppressed microbial activity during the ensuing anoxic conditions. Both the mid-chain and long chain n-ket/precursor ratios displayed predominant water level fluctuation controls, with temperature as a secondary regulator. By comparing the n-ket data with published environmental and climate reconstructions from the same core, and with geomorphology and palynological studies of the Mfabeni basin, we conclude that the n-kets show promise as a palaeoclimate proxy and can be used in conjunction with other biomarker proxies to reconstruct ancient hydrological changes in sub-tropical peatlands. (C) 2018 Elsevier Ltd. All rights reserved.

    The full text will be freely available from 2020-03-08 12:13
  • 4.
    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.

  • 5.
    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.

  • 6.
    Gayantha, Kasun
    et al.
    University of Peradeniya, Sri Lanka; University of Peradeniya, Sri Lanka.
    Routh, Joyanto
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Chandrajith, Rohana
    University of Peradeniya, Sri Lanka; University of Peradeniya, Sri Lanka.
    A multi-proxy reconstruction of the late Holocene climate evolution in Lake Bolgoda, Sri Lanka2017In: Palaeogeography, Palaeoclimatology, Palaeoecology, ISSN 0031-0182, E-ISSN 1872-616X, Vol. 473, p. 16-25Article in journal (Refereed)
    Abstract [en]

    Palaeoclimate investigations in Sri Lanka have been rarely attempted despite being located directly in the path of the Inter Tropical Convergence Zone. In this study, a 4.1-m undisturbed sediment core was retrieved from the Bolgoda Lake situated in the western coast of Sri Lanka, and influenced by the strong southwest monsoons. Mollusc shells in the core were dated, and the age-depth model indicated a depositional history extending from 2941 cal yr BP to the present. Grain size, major and trace elements, total organic C and N content and stable C and N isotopes were analysed in freeze-dried sediments to reconstruct the palaeoclimate changes. The multi proxy records in the core revealed four distinct zones that show distinct variations in physical and chemical conditions in the lake associated with climate change. Zone 1 (2941 to 2390 cal yr BP; 385-252 cm) indicated the climate to be warm and humid with intense precipitation. The resulting high lake level helped in organic matter preservation in bottom sediments. Zone 2 (2390 to 1782 cal yr BP; 252-140 cm) indicated an unstable dry period associated with weak precipitation. Consequently, low lake level and intense degradation of organic matter occurred in this zone. Zone 3 (1782 to 1299 cal yr BP; 140-60 cm) indicated a resurgence of intense monsoon along with warm and humid conditions. Zone 4 (1299 cal yr BP to present; 60-0 cm) indicated dry conditions with less intense monsoon, low lake level and extensive degradation of organic matter. Vascular plants were the predominant organic matter source into the lake during the late Holocene. In contrast, algal input was significant between 2390 cal yr BP and 2153 cal yr BP. The palaeoclimate evidences in this study showed an overall weakening trend of SW monsoon during the late Holocene, and this was consistent with changes happening in other locations as in southern and western India. (C) 2017 Elsevier B.V. All rights reserved.

  • 7.
    Johansson, Nils
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology.
    Defensiv strategi för återvinning av metaller2014In: Svenska Dagbladet, ISSN 1101-2412Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Regeringen satsar på gruvor i stället för återvinning. Mindre än 1 procent av de flesta sällsynta metallerna återvinns när de tas ur drift. I stället hamnar de på soptippar eller i naturen, skriver sju forskare i en slutreplik.

  • 8.
    Johansson, Nils
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology.
    Deponier som gruvor: Förekomst och förutsättningar för att utvinna basmetaller från svenska deponier2014Report (Other academic)
    Abstract [en]

    Ända sedan den första gruvan i de paleolitiska samhällena för 450 000 år sedan (Lewis och Clark, 1964) har människan successivt flyttat metallresurser från jordskorpan in till samhället i byggnader, infrastruktur, produkter och avfallshögar. Det pågår således ett geologiskt skifte (Johansson, 2013), som accelererade i samband med industrialiseringen, där metaller omlokaliseras till den bebyggda miljön på bekostnad av de geologiska reserverna. Vissa forskare menar att människan har blivit en geologisk kraft så till den grad att för vissa metaller som järn och koppar är mängderna jämförbara i samhället med reserverna i jordskorpan (Lichtensteiger, 2002;. Elshkaki et al, 2004; Spatari et al. 2005, Müller et al, 2006; Halada et al, 2009; Johansson, 2013).

    Soptippar, eller mer formellt deponier, är ett av förråden ovanför jordytan som har fått allt mer uppmärksamhet, eftersom de i sin roll av att vara i slutet av materialflödet fångar upp en stor andel av metallerna på ett avgränsat område. Om deponier definieras i vid mening till att inkludera alla former av avfallsupplag, dvs. även till exempel gruvavfall, så återfinns troligen 50 % av alla uppgrävda metaller i dessa inaktiva förråd (Johansson et al., 2013; Kapur, 2006; Graedel and Kapur 2006). Ur ett globalt perspektiv innebär detta att exempelvis mängden koppar i avfallsupplag motsvarar hälften av de kvarvarande mängderna i jordskorpans reserver (Johansson et al., 2013).

    Även om avfallsupplag avgränsas till inflöden av industriellt avfall (exklusive gruvavfall) och hushållsavfall så är metallinnehållet signifikant. Materialflödesanalyser av koppar och järn har påvisat att mellan 10-20 % av metallerna ovanför jordytan finns i dessa förråd (Johansson et al., 2013). Visserligen är deponering av hushållsavfall idag begränsad, men sedan industrialiseringen har deponeringen varit den vanligaste avfallshaneringsmetoden i Sverige. Detta innebär att i stort sett varje by har sin egen soptipp med stora mängder metaller och andra resurser placerade på hög. Uppskattningsvis finns över 4000 kommunala soptippar i Sverige med varierande storlek (Frändegård et al., 2013).

    Vid sidan av kommunala soptippar finns det även industriella soptippar som är placerade direkt i anknytning till en verksamhet. Uppskattningar har antytt att det finns upp till 1000 industriella soptippar i Sverige. Till skillnad från hushållsavfall deponeras fortfarande signifikanta mängder industriellt avfall i form av till exempel schaktmassor och aska (Naturvårdsverket, 2012a). Det saknas dock mer detaljerade studier av mängderna av olika metaller i industriella och kommunala deponier samt de tekniska och institutionella förutsättningarna för att bryta dessa metaller. Kan deponier vara framtidens gruvor?

  • 9.
    Johansson, Nils
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology.
    Framtidens gruva är hållbar2014In: Svenska dagbladet, ISSN 1101-2412, Vol. 06-24, p. 1Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Sveriges mineralpolitik är ensidigt fokuserad på att förbättra förutsättningarna för traditionell gruvnäring. Trots det växer intresset för att utvinna metaller från rivna byggnader, omodern teknisk utrustning, soptippar och infrastruktursystem.

  • 10.
    Johansson, Nils
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology.
    Omformulera Svensk metallpolitik2015In: Landets Fria Tidning, ISSN 2001-7448, , p. 1Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    I form av produkter som elektronik, infrastruktur och konstruktionsmaterial, flyttar människan enorma mängder metaller från gruvor i jordskorpan in i våra samhällen. Människan har blivit en geologisk kraft och en del forskare menar att vissa metallmängder i den byggda miljön är jämförbara i storlek med de mängder som finns kvar i jordskorpans reserver. I Sveriges samlade el- och telenät finns till exempel lika mycket koppar som det finns kvar i Aitikgruvan utanför Gällivare, en av Europas största koppargruvor. En stor del av metallerna är alltjämt i användning, men lika stora mängder har förlorats i olika avfallshögar som gruvavfall och soptippar. Utöver återvinningen av metaller från det årliga avfallsflödet, till exempel pantburkar, finns det således en stor potential att uppnå en bättre samhällelig resurseffektivitet. I dagsläget återvinns dessutom endast ungefär hälften av alla metalltyper som samlas in som avfall. Kritiska metaller som sällsynta jordartsmetaller återvinns inte alls, vilket innebär att medan prospekterare letar efter dessa metaller i jordskorpan låter vi de som redan finns nära oss gå förlorade.

  • 11.
    Johansson, Nils
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology.
    Politikerna hämnar metallåtervinning2014In: Avfall och Miljö, ISSN 0284-1827, no 3, p. 1p. 44-44Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Indirekt stödje staten gruvsektorn med enorma summor pengar varje år. Det leder till ojämna marknadsvillkor och att återvinningsbranschen inte utvecklas i den takt som den skulle kunna, exempelvis via landfill mining.

  • 12.
    Johansson, Nils
    et al.
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    Krook, Joakim
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    Frändegård, Per
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    A new dawn for buried garbage?: An investigation of the marketability of previously disposed shredder waste2017In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 60, p. 417-427Article in journal (Refereed)
    Abstract [en]

    This paper examines the market potential of disposed shredder waste, a resource that is increasingly emphasized as a future mine. A framework with gate requirements of various outlets was developed and contrasted with a pilot project focusing on excavated waste from a shredder landfill, sorted in an advanced recycling facility. Only the smallest fraction by percentage had an outlet, the metals (8%), which were sold according to a lower quality class. The other fractions (92%) were not accepted for incineration, as construction materials or even for re-deposition. Previous studies have shown similar lack of marketability. This means that even if one fraction can be recovered, the outlet of the other material is often unpredictable, resulting in a waste disposal problem, which easily prevents a landfill mining project altogether. This calls for marketability and usability of deposited waste to become a central issue for landfill mining research. The paper concludes by discussing how concerned actors can enhance the marketability, for example by pre-treating the disposed waste to acclimatize it to existing sorting methods. However, for concerned actors to become interested in approaching unconventional resources such as deposited waste, greater regulatory flexibility is needed in which, for example, re-deposition could be allowed as long as the environmental benefits of the projects outweigh the disadvantages.

  • 13.
    Krasnoshchekov, Dmitry
    et al.
    Russian Acad Sci, Russia.
    Ovtchinnikov, Vladimir
    Russian Acad Sci, Russia.
    Polishchuk, Valentin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Dissimilarity of the Earths Inner Core Surface Under South America and Northeastern Asia Revealed by Core Reflected Phases2019In: Journal of Geophysical Research - Solid Earth, ISSN 2169-9313, E-ISSN 2169-9356, Vol. 124, no 5, p. 4862-4878Article in journal (Refereed)
    Abstract [en]

    Resolving topography of the inner core boundary (ICB) and the structure and composition of the nearby region is key to improving our understanding of solidification of the Earths inner core. Observations of travel times and amplitudes of short-period seismic phases of PKiKP and PcP reflected, respectively, off the inner and outer boundary of the liquid core, provide essential constraints on the properties of this region. We revisit heterogeneities of ICB using a total of more than 1,300 new differential travel times and amplitude ratios of PKiKP and PcP measured at 3.2-35.2 degrees and reflected off the cores boundaries under Northeastern Asia and South America. We observe a statistically significant systematic bias between the measurements collected in the two spots. We carefully examine its origin in terms of contributions by various Earths shells and find that most of variance in PKiKP-PcP differential travel times measured above the epicentral distance of 16.5 degrees in Northeastern Asia can be accounted for by mantle corrections. We find slight disparity of about 1-3 km between the outer core thickness under Asia and America; the ICB density jump under Northeastern Asia is about 0.3 g/cm(3), which is three times as small as under South America. The findings are interpretable either as evidence for inner core hemispherical asymmetry, whereby crystallization dominates in the West and melting in the East (not vice versa), or in terms of two disconnected mosaic patches with contrasting properties.

  • 14.
    Paus, Aage
    et al.
    Univ Bergen, Norway.
    Haflidason, Haflidi
    Univ Bergen, Norway.
    Routh, Joyanto
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Naafs, B. David A.
    Univ Bristol, England.
    Thoen, Mani W.
    Univ Bergen, Norway.
    Environmental responses to the 9.7 and 8.2 cold events at two ecotonal sites in the Dovre mountains, mid-Norway2019In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 205, p. 45-61Article in journal (Refereed)
    Abstract [en]

    We found strong signals of two cooling events around 9700 and 8200 cal yrs. BP in lakes Store Finnsjoen and Flafattjonna at Dovre, mid-Norway. Analyses included pollen in both lakes, and C/N-ratio, biomarkers (e.g. alkanes and br-GDGT5), and XRF scanning in Finnsjoen. The positions of these lakes close to ecotones (upper forest-lines of birch and pine, respectively) reduced their resilience to cold events causing vegetation regression at both sites. The global 8.2 event reflects the collapse of the Laurentide Ice Sheet. The 9.7 event with impact restricted to Scandinavia and traced by pollen at Dovre only, reflects the drainage of the Baltic Ancylus Lake. More detailed analysis in Finnsjoen shows that the events also caused increased allochtonous input (K, Ca), increased sedimentation rate, and decreased sediment density and aquatic production. br-GDGT-based temperatures indicate gradual cooling through the early Holocene. In Finnsjoen, ca. 3100 maxima-minima couplets in sediment density along the analysed sequence of ca. 3100 calibrated years show the presence of varves for the first time in Norway. Impact of the 9.7 and 8.2 events lasted ca. 60 and 370 years, respectively. Pine pollen percentages were halved and re-established in less than 60 years, indicating the reduction of pine pollen production and not vegetative growth during the 9.7 event. The local impact of the 8.2 event sensu lato (ca. 8420-8050 cal yrs. BP) divides the event into a precursor, an erosional phase, and a recovery phase. At the onset of the erosional phase, summer temperatures increased. (C) 2018 Elsevier Ltd. All rights reserved.

  • 15.
    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

  • 16.
    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.

  • 17.
    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.

  • 18.
    Routh, Joyanto
    et al.
    Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden.
    Meyers,, Philip
    Department of Geological Sciences, University of Michigan, Ann Arbor, USA.
    Hjorth, Tomas
    Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden.
    Baskaran, Mark
    Department of Geology, Wayne State University, Detroit, USA.
    Hallberg, Rolf
    Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden.
    Sedimentary geochemical record of recent environmental changes around Lake Middle Marviken, Sweden2007In: Journal of Paleolimnology, ISSN 0921-2728, E-ISSN 1573-0417, Vol. 37, no 4, p. 529-545Article in journal (Refereed)
    Abstract [en]

    Geochemical properties of sediments deposited in Lake Middle Marviken over the last 185 years record the impacts of a succession of environmental changes that have occurred in the watershed. Clear-cutting of forests for wood and charcoal and extensive water harnessing to support the local iron mills from 1897 to 1957 is recorded by low C/N ratios, high black carbon, and low TOC and Ntotal accumulation rates. Larger δ13C and δ15N values in sediments deposited during this period imply higher productivity. Fluctuations in Ntotal and Ptotal accumulation rates show that the lake chemistry has varied between P or N-depleted systems that affected the δ15N values. Organic matter in the sediments is predominantly immature terrestrial material. Furthermore, hydrocarbon CPI, TAR, and Paq values conform with the observed geochemical trends, variations in organic matter sources, and changes in the watershed. Accumulation rates of Cd, Pb, Zn, and S remained mostly unchanged throughout the period of mining, but an increase from 1957 to 1980 is most likely associated with air-borne industrial and fossil fuel emissions from regional urbanization. In situ microbial processes, such as iron and manganese reduction, also appear to be important in carbon cycling and in affecting the sediment and water chemistry of this lake.

  • 19.
    Routh, Joyanto
    et al.
    Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden.
    Saraswathy, Ambujom
    Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden.
    Collins, Matthew D.
    School of Food Biosciences, University of Reading, Reading, Berkshire, UK.
    Arsenicicoccus bolidensis a novel arsenic reducing actinomycete in contaminated sediments near the Adak mine (northern Sweden): Impact on water chemistry2007In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 379, no 2-3, p. 216-225Article in journal (Refereed)
    Abstract [en]

    Weathering of mine tailings in Adak results in high As concentrations in surface and ground water, sediments, and soil. In spite of the oxic conditions, As-rich surface and ground water samples indicate As(III) species predominantly (up to 83%). Several microorganisms were isolated from the enrichment cultures that were involved in As cycling. Amongst them was Arsenicicoccus bolidensis — a novel gram-positive, facultatively anaerobic, coccus-shaped actinomycete, which actively reduced As(V) to As(III) in aqueous media. A. bolidensis reduced 0.06–0.20 mM day− 1 As(V). As(V) reduction displays a direct correlation between the initial As(V) concentration, growth rate, and biomass yield.

  • 20.
    Sanders, Luciana M.
    et al.
    Southern Cross University, Australia.
    Taffs, Kathryn H.
    Southern Cross University, Australia.
    Stokes, Debra
    Southern Cross University, Australia.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. University of Federal Rio de Janeiro, Brazil.
    Sanders, Christian J.
    Southern Cross University, Australia.
    Pu240+239 DEPOSITIONAL SIGNATURES AS A VIABLE GEOCHRONOLOGICAL TOOL IN THE AMAZON BASIN2017In: Geochronometria, ISSN 1733-8387, E-ISSN 1897-1695, Vol. 44, no 1, p. 142-149Article in journal (Refereed)
    Abstract [en]

    Anthropogenic radionuclide signatures associated with nuclear testing are increasingly utilized in environmental science to explore recent sedimentation. In this study, we assess the suitability of Pu radioisotope analysis in floodplain lake environments in the Amazon Basin to form geochronologies during the 20th century. The Pu-240 + Pu-239 (Pu240+239) signatures in six sediment cores indicate sediment accumulation rates in the floodplain lakes of the major rivers; Amazon (2.3 mm year(-1)), Tapajos (10.2 and 2.4 mm year(-1)) and Madeira (3.4, 4.2 and 6.2 mm year(-1)). The results from this study show that Pu240+239 fallout activities, and the well documented (Pu-240/Pu-239) atomic ratios of the above ground nuclear tests which began in the 1950s, are sufficient and well preserved in Amazon flood-plain lake sediments to infer chronologies. Lead-210 dating analyses in the same sediment cores produced comparable sediment accumulation rates at three of the six sites. The differences between dating methods may be attributed to the different time scale these dating methods represent and/or in the solubility between Pb and Pu along the sediment column. The geochronologies derived from the Pu240+239 and Pb-210 methods outlined in this work are of interest to identify the effects of changing sediment accumulation rates during the previous century as a result of development, including deforestation, along the Amazon Basin which increased towards the middle of the 20th century. This study shows that Pu dating provides a viable alternative geochronology tool for recent sediment accumulation (previous similar to 60 years) along the Amazon Basin.

  • 21.
    Sanders, Luciana M.
    et al.
    Southern Cross Univ, Australia.
    Taffs, Kathryn
    Southern Cross Univ, Australia.
    Stokes, Debra
    Southern Cross Univ, Australia.
    Sanders, Christian J.
    Southern Cross Univ, Australia.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Amora, Leonardo Nogueira
    Univ Fed Fluminense, Brazil.
    Marotta, Humberto
    Univ Fed Fluminense, Brazil.
    Historic carbon burial spike in an Amazon floodplain lake linked to riparian deforestation near Santarem, Brazil2018In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 15, no 2, p. 447-455Article in journal (Refereed)
    Abstract [en]

    Forests along the Amazon Basin produce significant quantities of organic material, a portion of which is deposited in floodplain lakes. Deforestation in the watershed may then have potentially important effects on the carbon fluxes. In this study, a sediment core was extracted from an Amazon floodplain lake to examine the relationship between carbon burial and changing land cover and land use. Historical records from the 1930s and satellite data from the 1970s were used to calculate deforestation rates between 1930 to 1970 and 1970 to 2010 in four zones with different distances from the margins of the lake and its tributaries (100, 500, 1000 and 6000m buffers). A sediment accumulation rate of similar to 4 mmyr(-1) for the previous similar to 120 years was determined from the Pu240+239 signatures and the excess Pb-210 method. The carbon burial rates ranged between 85 and 298 gCm(-2) yr(-1), with pulses of high carbon burial in the 1950s, originating from the forest vegetation as indicated by delta C-13 and delta N-15 signatures. Our results revealed a potentially important spatial dependence of the organic carbon (OC) burial in Amazon lacustrine sediments in relation to deforestation rates in the catchment. These deforestation rates were more intense in the riparian vegetation (100m buffer) during the period 1930 to 1970 and the larger open water areas (500, 1000 and 6000m buffer) during 1970 to 2010. The continued removal of vegetation from the interior of the forest was not related to the peak of OC burial in the lake, but only the riparian deforestation which peaked during the 1950s. Therefore, this supports the conservation priority of riparian forests as an important management practice for Amazon flooded areas. Our findings suggest the importance of abrupt and temporary events in which some of the biomass released by deforestation, especially restricted to areas along open water edges, might reach the depositional environments in the floodplain of the Amazon Basin.

  • 22.
    Skelton, Alasdair
    et al.
    Department of Geological Sciences, Stockholm University, Stockholm, Sweden.
    Claesson, Lillemor
    Department of Geological Sciences, Stockholm University, Stockholm, Sweden.
    Chakrapani, Govinda
    School of Ecology and Environment Studies, Nalanda Univeristy, India .
    Mahanta, Chandan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljögeokemi och ekoteknik.
    Routh, Joyanto
    Department of Geological Sciences, Stockholm University, Stockholm, Sweden.
    Mörth, Carl-Magnus
    Department of Geological Sciences, Stockholm University, Stockholm, Sweden.
    Khanna, Param
    Wadia Institute of Himalayan Geology, Dehra Dun, India.
    Seismic-hydrogeochemical coupling in north-eastern India2008In: 33rd International Geological Congress Oslo August 6 -14th 2008 General Proceedings, EurekaMag.com , 2008Conference paper (Other academic)
    Abstract [en]

    We report the result of a hydrogeochemical monitoring program, which has been operational north of the Shillong Plateau, Assam, India from December 2003. The aim of this ongoing study is to test for coupling between the groundwater chemistry collected from a granite-hosted aquifer, located at a depth of 110m, and seismic activity. Based on molar Na+/Ca2+ and molar HCO3-/SiO2 ratios after Garrels (1967), we interpret that groundwater chemistry is normally buffered by the alteration of feldspar (plagioclase) to kaolinite.

    During the study, we monitored transient chemical changes which coincided temporally with a period of increased seismic activity. This included (1) MW = 5.3 and MW = 5.0 earthquakes which occurred on December 9, 2004 and February 15, 2005, south of the Shillong Plateau and 206 and 213 km from the sampling station, respectively, and (2) the Great Sumatra – Andaman Islands Earthquake of December 26, 2004. These are the only three MW > 5 earthquakes which have occurred during our study and for which our monitoring site is within their respective strain radii as given by Dobrovolsky et al. (1979).

    The most dramatic chemical change was a coincident and approximately 2-fold increase of the ratios [Na+K]/Si, Na/K and [Na+K]/Ca. This was accompanied by significant increases of conductivity, alkalinity and chloride concentration. The onset of this chemical shift occurred 3-5 weeks before the first (MW = 5.3) earthquake. We interpret a transient switchover between source aquifers, which induced an influx of groundwater from a second and probably deeper 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. We also recorded a rapid drop in the ratio Ba/Sr, which occurred 3-6 days before the final (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. Both of these changes were transient and “recovery” occurred over periods of 2-4 weeks. By comparison with experimental studies of feldspar dissolution, we suggest that hydrogeochemical recovery was facilitated by groundwater interaction and clay mineralization, which could have been coupled with fracture sealing.

    The main argument in support of seismic-hydrogeochemical coupling is the coincidence in timing of two hydrogeochemical events with two MW  5 earthquakes. Reasons for ambiguity include the lack of similar hydrogeochemical anomalies temporally coupled with smaller seismic events which occurred much closer to 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. The hydrogeochemical anomalies reported in this study meet some of the validation criteria of the IASPEI (International Association of Seismology and Physics of the Earth’s Interior) sub-commission on earthquake prediction (Wyss, 1991; 1997) in that a relation to pre-seismic stress and that some dependence on distance from the earthquake foci is inferred. However, hydrogeochemical data was collected from only one site, and even although the hydrogeochemical anomalies are recorded using several instrumental methods the reported anomalies are not truly independent of one another.

  • 23.
    Stoetter, Tabea
    et al.
    Univ Bern, Switzerland.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Bodelier, Paul L. E.
    Netherlands Inst Ecol NIOO KNAW, Netherlands.
    van Hardenbroek, Maarten
    Univ Bern, Switzerland; Univ Bern, Switzerland; Newcastle Univ, England.
    Rinta, Paeivi
    Univ Bern, Switzerland.
    Schilder, Jos
    Univ Bern, Switzerland; Univ Jyvaskyla, Finland.
    Schubert, Carsten J.
    EAWAG, Switzerland.
    Heiri, Oliver
    Univ Bern, Switzerland; Univ Bern, Switzerland.
    Abundance and delta C-13 values of fatty acids in lacustrine surface sediments: Relationships with in-lake methane concentrations2018In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 191, p. 337-347Article in journal (Refereed)
    Abstract [en]

    Proxy-indicators in lake sediments provide the only approach by which the dynamics of in-lake methane cycling can be examined on multi-decadal to centennial time scales. This information is necessary to constrain how lacustrine methane production, oxidation and emissions are expected to respond to global change drivers. Several of the available proxies for reconstructing methane cycle changes of lakes rely on interpreting past changes in the abundance or relevance of methane oxidizing bacteria (MOB), either directly (e.g. via analysis of bacterial lipids) or indirectly (e.g. via reconstructions of the past relevance of MOB in invertebrate diet). However, only limited information is available about the extent to which, at the ecosystem scale, variations in abundance and availability of MOB reflect past changes in in-lake methane concentrations. We present a study examining the abundances of fatty acids (FAs), particularly of C-13-depleted FM known to be produced by MOB, relative to methane concentrations in 29 small European lakes. 39 surface sediment samples were obtained from these lakes and FA abundances were compared with methane concentrations measured at the lake surface, 10 cm above the sediments and 10 cm within the sediments. Three of the FAs in the surface sediment samples, C-16(:1 omega 7c), C-16(:1 omega 5c/t), and C-18(:1 omega 7c) were characterized by lower delta C-13 values than the remaining FAs. We show that abundances of these FM, relative to other short-chain FAs produced in lake ecosystems, are related with sedimentary MOB concentrations assessed by quantitative polymerase chain reaction (qPCR). We observed positive relationships between methane concentrations and relative abundances of C-16:1 omega 7c, C-16:1 omega 5c/t, and C-18:1 omega 7c and the sum of these FAs. For the full dataset these relationships were relatively weak (Spearmans rank correlation (r(s)) of 0.34-0.43) and not significant if corrected for multiple testing. However, noticeably stronger and statistically significant relationships were observed when sediments from near-shore and deep-water oxic environments (r(s) = 0.57 to 0.62) and those from anoxic deep-water environment (r(s)= 0.55 to 0.65) were examined separately. Our results confirm that robust relationships exist between in-lake CH 4 concentrations and 13 C-depleted groups of FAs in the examined sediments, agreeing with earlier suggestions that the availability of MOB-derived, C-13-depleted organic matter for aquatic invertebrates increases with increasing methane concentrations. However, we also show that these relationships are complex, with different relationships observed for oxic and anoxic sediments and highest values measured in sediments deposited in oxic environments overlain with relatively methane-rich water. Furthermore, although all three C-13-depleted FA groups identified in our survey are known to be produced by MOB, they also receive contributions by other organism groups, and this will have influenced their distribution in our dataset. (C) 2018 Elsevier Ltd. All rights reserved.

  • 24.
    Vaezi, Alireza
    et al.
    Graduate Faculty of Environment, University of Tehran, Enghelab Square, Tehran 1417853111, Iran.
    Ghazban, Fereydoun
    Graduate Faculty of Environment, University of Tehran, Enghelab Square, Tehran 1417853111, Iran.
    Tavakoli, Vahid
    School of Geology, College of Science, University of Tehran, Enghelab Square, Tehran 1417853111, Iran.
    Routh, Joyanto
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Beni, Abdolmajid Naderi
    Iranian National Institute for Oceanography and Atmospheric Sciences, Etemadzadeh St, Tehran 1411813389, Iran.
    Bianchi, Thomas S.
    Department of Geological Sciences, University of Florida, Gainesville, FL 32611, USA.
    Curtis, Jason H.
    Department of Geological Sciences, University of Florida, Gainesville, FL 32611, USA.
    Kylin, Henrik
    Research Unit, Environmental Sciences and Management, North-West University, Potchefstroom, South Africa.
    A Late Pleistocene-Holocene multi-proxy record of climate variability in the Jazmurian playa, southeastern Iran2019In: Palaeogeography, Palaeoclimatology, Palaeoecology, ISSN 0031-0182, E-ISSN 1872-616X, Vol. 514, p. 754-767Article in journal (Refereed)
    Abstract [en]

    We present a multi-proxy record from a 5-m long sediment core from the Jazmurian playa in southeastern Iran to provide insights into globally-recognized major climatic events since the Last Glacial Maximum (LGM). In particular, we examined how variability in the Indian Ocean Summer Monsoon (IOSM) and Mid-Latitude Westerlies (MLW) contribute to distinct environmental changes in this arid to hyper-arid region in the interior of West Asia. While interior West Asia showed cold windy conditions during the LGM and post-LGM, southeast Iran experienced quiescent conditions similar to south Asia. The presence of fine-grained sediments, low magnetic susceptibility, and a decrease in aeolian inputs from ca. 21 to 14 cal kyr BP, suggests that effects of both wind and precipitation were minimal during these quiescent conditions. Increased fluvial inputs, coupled with a low abundance of evaporite minerals in Jazmurian sediments, indicated a greater influence of the IOSM between 14 and 13.2 cal kyr BP. In contrast, the Jazmurian playa was dry and dusty between 13.2 and 11.4 cal kyr BP, as reflected by an increase in aeolian sands, and the presence of evaporite minerals. This was followed by a period of strong IOSM activity during the early Holocene, coinciding with higher fluvial input ca. 11.4 cal kyr BP. The early Holocene in southeast Iran was wetter than other analogs in south Asia because of inputs from both IOSM and MWL. Several intense dry periods with sharp increases in aeolian inputs occurred after the early Holocene, due to the southward migration of the Intertropical Convergence Zone. Precipitation sources changed from a monsoon-dominated regime to one influenced mainly by the MLW during the late-Holocene. These results show that palaeoenvironmental changes in the Jazmurian playa, located at the border of IOSM and MLW zones, were primarily governed by global and regional paleoclimatic changes.

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