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1.
Ecotoxicol Environ Saf ; 207: 111228, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32890952

RESUMO

Atmospheric heavy metals have important environmental and health threats. To investigate atmospheric deposition and contamination of heavy metal elements in the glaciers of the eastern Tibetan Plateau (ETP), we collected the surface snow (cryoconites) samples in the Lenglongling Glacier (LG), the Gannan Snowpack (GS), the Dagu Glacier (DG), the Hailuogou Glacier (HG) and Yulong Snow-mountain Glacier (YG) in summer 2017. Samples were analyzed for concentrations and enrichment factors (EFs) of Al and trace elements (Pb, Co, Cd, Ba, Mn, Ga, Sc, V, Zn, Cr, Ni, Cu, Rb, Sb, Cs, As, Mo, Li) using inductively coupled plasma-mass spectrometry (ICP-MS). Results showed that the concentrations and EFs of heavy metals (e.g. Sb, Cu, Cr, Ni, As, Mo) were generally high value in YG, GS and LG, while were relatively low value in DG and HG, implying that ETP glaciers may have been affected by atmospheric anthropogenic pollutants deposition to varying degrees. Comparing the heavy metal concentrations in the glaciers with those in the precipitation of middle/eastern China cities and also the South Asian cities, we find that the glacial heavy metal concentrations were generally low level, though the anthropogenic pollutants were still significantly enriched. Taking the spatial distribution of As and Ni concentration/EFs in the glaciers and surrounding urban precipitation as an example, we find that the heavy metal pollutants were probably transported to the glaciers through three routes from the surrounding densely populated area of Asia. The MODIS AOD and NCEP/NCAR wind vector also demonstrated that the atmospheric pollutants originated from anthropogenic emissions of urban areas of both South Asia, and northwest and east China, mainly caused by the large scale atmospheric circulation (e.g. the South Asian Monsoon, westerlies and Eastern Asian Summer Monsoon). Therefore, control of these potential pollution emission sources of the surrounding densely populated areas in Asia could be important to ETP glaciers in future perspectives.


Assuntos
Monitoramento Ambiental , Camada de Gelo/química , Metais Pesados/análise , China , Poluição Ambiental/análise , Estações do Ano , Neve/química , Tibet , Oligoelementos/análise , Vento
2.
Ecotoxicol Environ Saf ; 203: 111037, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888596

RESUMO

Glacier studies as of late have ruffled many eyeballs, exploring this frigid ecology to understand the impact of climate change. Mapquesting the glaciers led to the discovery of concealed world of "psychrophiles" harboring in it. In the present study, the antibiotic resistance genes (ARGs) and heavy metal resistance genes (MRGs) were evaluated through both the culture-dependent and culture-independent methods. Samples were collected from two different glaciers, i.e., debris-covered glacier (Changme Khangpu) and debris-free glacier (Changme Khang). Functional metagenomics of both the glacier samples, provided evidence of presence of resistant genes against various antibiotic groups. Bacitracin resistant gene (bacA) was the predominant ARG in both the glaciers. MRGs in both the glacier samples were diversified as the genes detected were resistant against various heavy metals such as arsenic, tungsten, mercury, zinc, chromium, copper, cobalt, and iron. Unique MRGs identified from Changme Khangpu glacier were resistant to copper (cutA, cutE, cutC, cutF, cueR, copC, and copB) and chromium (yelf, ruvB, nfsA, chrR, and chrA) whereas, from Changme Khang glacier they showed resistance against cobalt (mgtA, dmef, corD, corC, corB, and cnrA), and iron (yefD, yefC, yefB, and yefA) heavy metals. ARGs aligned maximum identity with Gram-negative psychrotolerant bacteria. The cultured bacterial isolates showed tolerance to high concentrations of tested heavy metal solutions. Interestingly, some of the antibiotic resistant bacterial isolates also showed tolerance towards the higher concentrations of heavy metals. Thus, an introspection of the hypothesis of co-occurrence and/co-selection of ARGs and MRGs in such environments has been highlighted here.


Assuntos
Adaptação Biológica/genética , Antibacterianos/toxicidade , Resistência Microbiana a Medicamentos/genética , Poluentes Ambientais/toxicidade , Genes Bacterianos/efeitos dos fármacos , Camada de Gelo/microbiologia , Metais Pesados/toxicidade , Adaptação Biológica/efeitos dos fármacos , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Negativas/genética , Camada de Gelo/química , Índia , Metagenômica , Siquim
3.
Proc Natl Acad Sci U S A ; 117(36): 21928-21937, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32839314

RESUMO

Ice nucleation and the resulting cloud glaciation are significant atmospheric processes that affect the evolution of clouds and their properties including radiative forcing and precipitation, yet the sources and properties of atmospheric ice nucleants are poorly constrained. Heterogeneous ice nucleation caused by ice-nucleating particles (INPs) enables cloud glaciation at temperatures above the homogeneous freezing regime that starts near -35 °C. Biomass burning is a significant global source of atmospheric particles and a highly variable and poorly understood source of INPs. The nature of these INPs and how they relate to the fuel composition and its combustion are critical gaps in our understanding of the effects of biomass burning on the environment and climate. Here we show that the combustion process transforms inorganic elements naturally present in the biomass (not soil or dust) to form potentially ice-active minerals in both the bottom ash and emitted aerosol particles. These particles possess ice-nucleation activities high enough to be relevant to mixed-phase clouds and are active over a wide temperature range, nucleating ice at up to -13 °C. Certain inorganic elements can thus serve as indicators to predict the production of ice nucleants from the fuel. Combustion-derived minerals are an important but understudied source of INPs in natural biomass-burning aerosol emissions in addition to lofted primary soil and dust particles. These discoveries and insights should advance the realistic incorporation of biomass-burning INPs into atmospheric cloud and climate models. These mineral components produced in biomass-burning aerosol should also be studied in relation to other atmospheric chemistry processes, such as facilitating multiphase chemical reactions and nutrient availability.


Assuntos
Aerossóis/química , Cinza de Carvão/química , Camada de Gelo/química , Minerais/química , Atmosfera/química , Biomassa , Mudança Climática , Congelamento , Gelo/análise , Tamanho da Partícula , Incêndios Florestais
4.
Nature ; 584(7821): 393-397, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32814886

RESUMO

The rate of global-mean sea-level rise since 1900 has varied over time, but the contributing factors are still poorly understood1. Previous assessments found that the summed contributions of ice-mass loss, terrestrial water storage and thermal expansion of the ocean could not be reconciled with observed changes in global-mean sea level, implying that changes in sea level or some contributions to those changes were poorly constrained2,3. Recent improvements to observational data, our understanding of the main contributing processes to sea-level change and methods for estimating the individual contributions, mean another attempt at reconciliation is warranted. Here we present a probabilistic framework to reconstruct sea level since 1900 using independent observations and their inherent uncertainties. The sum of the contributions to sea-level change from thermal expansion of the ocean, ice-mass loss and changes in terrestrial water storage is consistent with the trends and multidecadal variability in observed sea level on both global and basin scales, which we reconstruct from tide-gauge records. Ice-mass loss-predominantly from glaciers-has caused twice as much sea-level rise since 1900 as has thermal expansion. Mass loss from glaciers and the Greenland Ice Sheet explains the high rates of global sea-level rise during the 1940s, while a sharp increase in water impoundment by artificial reservoirs is the main cause of the lower-than-average rates during the 1970s. The acceleration in sea-level rise since the 1970s is caused by the combination of thermal expansion of the ocean and increased ice-mass loss from Greenland. Our results reconcile the magnitude of observed global-mean sea-level rise since 1900 with estimates based on the underlying processes, implying that no additional processes are required to explain the observed changes in sea level since 1900.


Assuntos
Temperatura Alta , Camada de Gelo/química , Água do Mar/análise , Água do Mar/química , Monitoramento Ambiental , Aquecimento Global/estatística & dados numéricos , Groenlândia , História do Século XX , História do Século XXI , Probabilidade , Incerteza
5.
Chemosphere ; 259: 127433, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32593004

RESUMO

The Arctic region is substantially a pristine area, but this unique part of the globe has also been contaminated by anthropogenic radioactive nuclides, and now there is still measurable activity of anthropogenic isotopes, even though more than 50 years have passed since the main source. Radionuclides in the Arctic, especially 90Sr have seldom been studied despite their considerable environmental importance. This manuscript covers the results of 90Sr and 137Cs measurements in soil and lichen Cetrariella delisei collected from the Svalbard in 2012. In both lichen thalli and surface soils high activities of 90Sr and 137Cs were recorded and ranged between 3.69 and 28.1 Bq kg-1 90Sr and 5.38-280.1 Bq kg-1137Cs in thalli and between 4.53 and 12.78 Bq kg-1dw 90Sr and 60.6-426.1 Bq kg-1dw 137Cs in surface soil layer. The activity of 90Sr and 137Cs in lichen thalli was influenced by distance from the glacier. This showed that during radionuclide biomonitoring of particular area with the use of lichens, it is important to take into account influence of environmental variability on radionuclides contents.


Assuntos
Radioisótopos de Césio/análise , Camada de Gelo/química , Líquens/química , Radioisótopos de Estrôncio/análise , Regiões Árticas , Parmeliaceae , Monitoramento de Radiação/métodos , Solo , Poluentes Radioativos do Solo/análise , Svalbard , Poluentes Radioativos da Água/análise
6.
PLoS One ; 15(5): e0233513, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32437403

RESUMO

Due to climate change, numerous ice bodies have been lost in the West Antarctic Peninsula (WAP). As a consequence, deglaciation is expected to impact the marine environment and its biota at physiological and ecosystem levels. Nuculana inaequisculpta is a marine bivalve widely distributed around Antarctica that plays an important role for ecosystem functioning. Considering that N. inaequisculpta inhabits coastal areas under effect of glacial melt and retreat, impacts on its nutritional condition are expected due to alterations on its physiology and food availability. To test this hypothesis, biochemical composition (lipids, proteins, and fatty acids) and energy content were measured in individuals of N. inaequisculpta collected in a fjord at different distances to the retreating glacier in the WAP. Oceanographic parameters of the top and bottom-water layers (temperature, salinity, dissolved oxygen, and chlorophyll-a) were measured to investigate how the environment changes along the fjord. Results showed that surface oceanographic parameters displayed a lower temperature and dissolved oxygen, but a higher salinity and chlorophyll-a content at nearest compared to farthest sites to the glacier. In contrast, a lower temperature and chlorophyll-a, and a higher salinity and dissolved oxygen was measured in the bottom-water layer toward the glacier. N. inaequisculpta had a higher amount of lipids (17.42 ± 3.24 vs. 12.16 ± 3.46%), protein (24.34 ± 6.12 vs. 21.05 ± 2.46%) and energy content (50.57 ± 6.97 J vs. 39.14 ± 5.80 J) in the farthest compared to the nearest site to the glacier. No differences were found in total fatty acids among all sites. It seems likely that lower individual fitness related to proximity to the glacier would not be related to nutritional quality of sediment food, but rather to food quantity.


Assuntos
Bivalves/fisiologia , Mudança Climática , Camada de Gelo , Fenômenos Fisiológicos da Nutrição Animal , Animais , Regiões Antárticas , Bivalves/química , Ecossistema , Estuários , Ácidos Graxos/análise , Camada de Gelo/química , Lipídeos/análise , Proteínas/análise
7.
Chemosphere ; 251: 126399, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32163783

RESUMO

In this study, a shallow ice core (12.5 m, called LGB) was drilled at the Lambert Glacial Basin, East Antarctica. The major ion and metal elements were measured at 5-6 cm resolution in this shallow core, which covered the period 1990-2017. Therefore, an annual-resolution record of iron (Fe) concentrations and fluxes were reconstructed in this shallow ice core. Although the Fe data is comparable to previous results, our results emphasized that much more dissolved Fe (DFe) from the Cerro Hudson volcanic event (August 1991) was transported to the East Antarctic ice sheet, in comparison with the Pinatubo volcanic event (June 1991). The aeolian dust may be the primary DFe source during 1990-2017. In particular, the DFe variations may be affected by the biomass burning emissions in two periods (1990-1998 and 2014-2017). While total dissolved Fe (TDFe) variations were controlled by the climatic conditions since 2000 because of the temperature (δ18O) decreasing at East Antarctica. These Fe data will be useful to assess the modern bioavailable Fe release for the Antarctica ice sheet.


Assuntos
Monitoramento Ambiental , Camada de Gelo/química , Ferro/análise , Regiões Antárticas , Biomassa , Poeira/análise , Ferro/química , Metais , Temperatura
9.
Nat Commun ; 11(1): 1534, 2020 03 24.
Artigo em Inglês | MEDLINE | ID: mdl-32210225

RESUMO

Changes in ocean circulation and the biological carbon pump have been implicated as the drivers behind the rise in atmospheric CO2 across the last deglaciation; however, the processes involved remain uncertain. Previous records have hinted at a partitioning of deep ocean ventilation across the two major intervals of atmospheric CO2 rise, but the consequences of differential ventilation on the Si cycle has not been explored. Here we present three new records of silicon isotopes in diatoms and sponges from the Southern Ocean that together show increased Si supply from deep mixing during the deglaciation with a maximum during the Younger Dryas (YD). We suggest Antarctic sea ice and Atlantic overturning conditions favoured abyssal ocean ventilation at the YD and marked an interval of Si cycle reorganisation. By regulating the strength of the biological pump, the glacial-interglacial shift in the Si cycle may present an important control on Pleistocene CO2 concentrations.


Assuntos
Atmosfera/química , Camada de Gelo/química , Isótopos/metabolismo , Água do Mar/química , Silício/metabolismo , Movimentos da Água , Regiões Antárticas , Oceano Atlântico , Dióxido de Carbono/metabolismo , História Antiga , Isótopos/análise , Oceanografia/métodos , Paleontologia/métodos , Água do Mar/análise , Silício/análise , Temperatura
10.
Chemosphere ; 248: 126082, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32032884

RESUMO

The study investigates transformation mechanism of ions on different waters in Alpine region through analyzed the hydrochemical characteristics of the major ions of precipitation, glacier and snow meltwater, supra-permafrost water and river water in permafrost regions in the Tibetan Plateau under climate warming. The results showed that, The relation between recharge and discharge was the major ways for ionic transformation of each water body. Precipitation and glacier and snow meltwater are the main input sources for ionic transformation, and river water is the final output source. Different water bodies had different ionic concentrations and different hydrochemical types. However, different water bodies in different months (from June to September) also had different hydrochemical types. The water - rock interaction, reactions for ions, dilution effect and other effect for ions played an important role in the process of ion transformation. The increasing of temperature would lead to the accelerated melting of glaciers, permafrost and snow in the alpine regions, so the amount of supra-permafrost water and glacier and snow meltwater will increase, which leads to the increase of runoff. Meanwhile, the increase of temperature makes evaporation stronger. The strong of evaporation will accelerate the transformation of liquid water to gaseous water. Moreover, ion translation and water conversion are synchronous. Accordingly, ions are also accelerating transformation in the process of accelerated transformation of water body. Climate change is not only the main driving force for multiphase water transformation, but also the main driving force for the ion transformation of various water bodies.


Assuntos
Ânions/análise , Cátions/análise , Mudança Climática , Camada de Gelo/química , Rios/química , Neve/química , Altitude , China , Congelamento , Modelos Teóricos , Estações do Ano
11.
Nature ; 578(7795): 409-412, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32076219

RESUMO

Atmospheric methane (CH4) is a potent greenhouse gas, and its mole fraction has more than doubled since the preindustrial era1. Fossil fuel extraction and use are among the largest anthropogenic sources of CH4 emissions, but the precise magnitude of these contributions is a subject of debate2,3. Carbon-14 in CH4 (14CH4) can be used to distinguish between fossil (14C-free) CH4 emissions and contemporaneous biogenic sources; however, poorly constrained direct 14CH4 emissions from nuclear reactors have complicated this approach since the middle of the 20th century4,5. Moreover, the partitioning of total fossil CH4 emissions (presently 172 to 195 teragrams CH4 per year)2,3 between anthropogenic and natural geological sources (such as seeps and mud volcanoes) is under debate; emission inventories suggest that the latter account for about 40 to 60 teragrams CH4 per year6,7. Geological emissions were less than 15.4 teragrams CH4 per year at the end of the Pleistocene, about 11,600 years ago8, but that period is an imperfect analogue for present-day emissions owing to the large terrestrial ice sheet cover, lower sea level and extensive permafrost. Here we use preindustrial-era ice core 14CH4 measurements to show that natural geological CH4 emissions to the atmosphere were about 1.6 teragrams CH4 per year, with a maximum of 5.4 teragrams CH4 per year (95 per cent confidence limit)-an order of magnitude lower than the currently used estimates. This result indicates that anthropogenic fossil CH4 emissions are underestimated by about 38 to 58 teragrams CH4 per year, or about 25 to 40 per cent of recent estimates. Our record highlights the human impact on the atmosphere and climate, provides a firm target for inventories of the global CH4 budget, and will help to inform strategies for targeted emission reductions9,10.


Assuntos
Atmosfera/química , Combustíveis Fósseis/história , Combustíveis Fósseis/provisão & distribução , Atividades Humanas/história , Metano/análise , Metano/história , Biomassa , Radioisótopos de Carbono , Carvão Mineral/história , Carvão Mineral/provisão & distribução , Aquecimento Global/prevenção & controle , Aquecimento Global/estatística & dados numéricos , História do Século XVIII , História do Século XIX , História do Século XX , História do Século XXI , Camada de Gelo/química , Metano/química , Gás Natural/história , Gás Natural/provisão & distribução , Petróleo/história , Petróleo/provisão & distribução
12.
Nature ; 577(7792): 660-664, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31996820

RESUMO

Sea-level histories during the two most recent deglacial-interglacial intervals show substantial differences1-3 despite both periods undergoing similar changes in global mean temperature4,5 and forcing from greenhouse gases6. Although the last interglaciation (LIG) experienced stronger boreal summer insolation forcing than the present interglaciation7, understanding why LIG global mean sea level may have been six to nine metres higher than today has proven particularly challenging2. Extensive areas of polar ice sheets were grounded below sea level during both glacial and interglacial periods, with grounding lines and fringing ice shelves extending onto continental shelves8. This suggests that oceanic forcing by subsurface warming may also have contributed to ice-sheet loss9-12 analogous to ongoing changes in the Antarctic13,14 and Greenland15 ice sheets. Such forcing would have been especially effective during glacial periods, when the Atlantic Meridional Overturning Circulation (AMOC) experienced large variations on millennial timescales16, with a reduction of the AMOC causing subsurface warming throughout much of the Atlantic basin9,12,17. Here we show that greater subsurface warming induced by the longer period of reduced AMOC during the penultimate deglaciation can explain the more-rapid sea-level rise compared with the last deglaciation. This greater forcing also contributed to excess loss from the Greenland and Antarctic ice sheets during the LIG, causing global mean sea level to rise at least four metres above modern levels. When accounting for the combined influences of penultimate and LIG deglaciation on glacial isostatic adjustment, this excess loss of polar ice during the LIG can explain much of the relative sea level recorded by fossil coral reefs and speleothems at intermediate- and far-field sites.


Assuntos
Camada de Gelo , Elevação do Nível do Mar/história , Água do Mar/análise , Animais , Regiões Antárticas , Antozoários , Recifes de Corais , Foraminíferos , Fósseis , Groenlândia , História Antiga , Camada de Gelo/química , Modelos Teóricos , Temperatura
13.
Proc Natl Acad Sci U S A ; 117(4): 2049-2055, 2020 01 28.
Artigo em Inglês | MEDLINE | ID: mdl-31932430

RESUMO

As global climate continues to warm, melting of glaciers releases a large quantity of mercury (Hg) originally locked in ice into the atmosphere and downstream ecosystems. Here, we show an opposite process that captures atmospheric Hg through glacier-to-vegetation succession. Our study using stable isotope techniques at 3 succession sites on the Tibetan Plateau reveals that evolving vegetation serves as an active "pump" to take up gaseous elemental mercury (Hg0) from the atmosphere. The accelerated uptake enriches the Hg pool size in glacier-retreated areas by a factor of ∼10 compared with the original pool size in the glacier. Through an assessment of Hg source-sink relationship observed in documented glacier-retreated areas in the world (7 sites of tundra/steppe succession and 5 sites of forest succession), we estimate that 400 to 600 Mg of Hg has been accumulated in glacier-retreated areas (5‰ of the global land surface) since the Little Ice Age (∼1850). By 2100, an additional ∼300 Mg of Hg will be sequestered from the atmosphere in glacier-retreated regions globally, which is ∼3 times the total Hg mass loss by meltwater efflux (∼95 Mg) in alpine and subpolar glacier regions. The recapturing of atmospheric Hg by vegetation in glacier-retreated areas is not accounted for in current global Hg models. Similar processes are likely to occur in other regions that experience increased vegetation due to climate or land use changes, which need to be considered in the assessment of global Hg cycling.


Assuntos
Aquecimento Global , Camada de Gelo/química , Mercúrio/análise , Poluentes Atmosféricos/análise , Ecossistema , Monitoramento Ambiental , Plantas/química , Plantas/metabolismo , Poluentes do Solo/análise , Poluentes do Solo/metabolismo , Tibet , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/metabolismo
14.
Chemosphere ; 240: 124938, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31574444

RESUMO

Clearwater Mesa (James Ross Island, northeast Antarctic Peninsula) provides a unique opportunity to study solute dynamics and geochemical weathering in the pristine lacustrine systems of a high latitude environment. In order to determine major controls on the solute composition of these habitats, a geochemical survey was conducted on 35 lakes. Differences between lakes were observed based on measured physico-chemical parameters, revealing neutral to alkaline waters with total dissolved solids (TDS) < 2500 mg L-1. Katerina and Trinidad-Tatana systems showed an increase in their respective TDS, total organic carbon values, and finner sediments from external to internal lakes, indicating an accumulation of solutes due to weathering. Norma and Florencia systems exhibited the most diluted and circumneutral waters, likely from the influence of glacier and snow melt. Finally, isolated lakes presented large variability in TDS values, indicating weathering and meltwater contributions at different proportions. Trace metal abundances revealed a volcanic mineral weathering source, except for Pb and Zn, which could potentially indicate atmospheric inputs. Geochemical modelling was also conducted on a subset of connected lakes to gain greater insight into processes determining solute composition, resulting in the weathering of salts, carbonates and silicates with the corresponding generation of clays. We found CO2 consumption accounted for 20-30% of the total species involved in weathering reactions. These observations allow insights into naturally occurring geochemical processes in a pristine environment, while also providing baseline data for future research assessing the impacts of anthropogenic pollution and the effects of climate change.


Assuntos
Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Lagos/química , Minerais/análise , Compostos Orgânicos/análise , Oligoelementos/análise , Regiões Antárticas , Carbonatos/análise , Mudança Climática , Ecossistema , Camada de Gelo/química , Chumbo/análise , Trinidad e Tobago , Tempo (Meteorologia) , Zinco/análise
15.
ISME J ; 14(3): 857-860, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-29379176

RESUMO

Earth has experienced glacial/interglacial oscillations accompanied by changes in atmospheric CO2 throughout much of its history. Today over 15 million square kilometers of Earth's land surface is covered in ice including glaciers, ice caps, and ice sheets. Glaciers are teeming with life and supraglacial snow and ice surfaces are often darkened by the presence of photoautotrophic snow algae, resulting in accelerated melt due to lowered albedo. Few studies report the productivity of snow algal communities and the parameters which constrain their growth on supraglacial surfaces-key factors for quantifying biologically induced albedo effects (bio-albedo). We demonstrate that snow algae primary productivity is stimulated by the addition of inorganic carbon. Our results indicate a positive feedback between increasing CO2 and snow algal primary productivity, underscoring the need for robust climate models of past and present glacial/interglacial oscillations to include feedbacks between supraglacial primary productivity, albedo, and atmospheric CO2.


Assuntos
Carbono/metabolismo , Clorófitas/metabolismo , Dióxido de Carbono/metabolismo , Clorófitas/crescimento & desenvolvimento , Clima , Congelamento , Camada de Gelo/química
16.
Environ Toxicol Chem ; 39(2): 335-342, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31743941

RESUMO

Coal-related elements are toxic and persistent pollutants that have spread globally since the industrial revolution, mainly from point-source emissions. A sediment core was collected from Deep Lake in northeastern Washington State (USA) by the Washington State Department of Ecology, with the aim of assessing recent changes in atmospheric deposition in the US Pacific Northwest. The core was divided into depth intervals and dated by lead-210. A sample from each cross section was digested and analyzed for toxic metals and metalloids using inductively coupled plasma-mass spectrometry. Data show recent increases in the concentrations of arsenic, barium, selenium, and mercury. Comparison with 1993 US Geological Survey ice core data from the Upper Fremont Glacier in Wyoming (USA), Asian coal consumption data, and weather patterns suggests that pollutant inputs to Deep Lake sediments are the result of coal-burning activities in the Asia-Pacific region. Most notably, mercury deposition in Deep Lake has increased from approximately 20 ppb in 1996 to 9470 ppb in 2014 (an ~400-fold increase), and since 1993 when the ice core was analyzed. Environ Toxicol Chem 2020;39:335-342. © 2019 SETAC.


Assuntos
Poluentes Atmosféricos/análise , Carvão Mineral/análise , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Lagos/química , Poluentes Químicos da Água/análise , Camada de Gelo/química , Radioisótopos de Chumbo , Mercúrio/análise , Washington
17.
J Environ Sci (China) ; 87: 389-397, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31791511

RESUMO

Carbonaceous matter has an important impact on glacial retreat in the Tibetan Plateau, further affecting the water resource supply. However, the related studies on carbonaceous matter are still scarce in Geladaindong (GLDD) region, the source of the Yangtze River. Therefore, the concentration, source and variations of carbonaceous matter at Ganglongjiama (GLJM) glacier in GLDD region were investigated during the melting period in 2017, which could deepen our understanding on carbonaceous matter contribution to glacier melting. The results showed that dissolved organic carbon (DOC) concentration of snowpit samples (283 ±â€¯200 µg/L) was much lower than that of precipitation samples (624 ±â€¯361 µg/L), indicating that large parts of DOC could be rapidly leached from the snowpit during the melting process. In contrast, refractory black carbon (rBC) concentration measured by Single Particle Soot Photometer of snowpit samples (4.27 ±â€¯3.15 µg/L) was much higher than that of precipitation samples (0.97 ±â€¯0.49 µg/L). Similarly, DOC with high mass absorption cross-section measured at 365 nm value was also likely to enrich in snowpit during the melting process. In addition, it was found that both rBC and DOC with high light-absorbing ability began to leach from the snowpit when melting process became stronger. Therefore, rBC and DOC with high light-absorbing ability exhibited similar behavior during the melting process. Based on relationship among DOC, rBC and K+ in precipitation, the main source of carbonaceous matter in GLJM glacier was biomass burning during the study period.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Rios/química , Biomassa , Carbono , Fracionamento Químico , Camada de Gelo/química , Fuligem
18.
Nat Commun ; 10(1): 5786, 2019 12 19.
Artigo em Inglês | MEDLINE | ID: mdl-31857591

RESUMO

Recent recession of the Larsen Ice Shelf C has revealed microbial alterations of illite in marine sediments, a process typically thought to occur during low-grade metamorphism. In situ breakdown of illite provides a previously-unobserved pathway for the release of dissolved Fe2+ to porewaters, thus enhancing clay-rich Antarctic sub-ice shelf sediments as an important source of Fe to Fe-limited surface Southern Ocean waters during ice shelf retreat after the Last Glacial Maximum. When sediments are underneath the ice shelf, Fe2+ from microbial reductive dissolution of illite/Fe-oxides may be exported to the water column. However, the initiation of an oxygenated, bioturbated sediment under receding ice shelves may oxidize Fe within surface porewaters, decreasing dissolved Fe2+ export to the ocean. Thus, we identify another ice-sheet feedback intimately tied to iron biogeochemistry during climate transitions. Further constraints on the geographical extent of this process will impact our understanding of iron-carbon feedbacks during major deglaciations.


Assuntos
Bactérias/metabolismo , Sedimentos Geológicos/microbiologia , Camada de Gelo/microbiologia , Ferro/química , Minerais/análise , Regiões Antárticas , Bactérias/química , Bactérias/isolamento & purificação , Sequestro de Carbono , Mudança Climática , Sedimentos Geológicos/química , Camada de Gelo/química , Oxigênio/química , Água do Mar/química , Água do Mar/microbiologia , Temperatura
19.
J Vis Exp ; (152)2019 10 26.
Artigo em Inglês | MEDLINE | ID: mdl-31710034

RESUMO

Global warming affects microbial communities in a variety of ecosystems, especially cryospheric habitats. However, little is known about microbial-mediated carbon fluxes in extreme environments. Hence, the methodology of sample acquisition described in the very few studies available implies two major problems: A) high resolution data require a large number of samples, which is difficult to obtain in remote areas; B) unavoidable sample manipulation such as cutting, sawing, and melting of ice cores that leads to a misunderstanding of in situ conditions. In this study, a prototype device that requires neither sample preparation nor sample destruction is presented. The device can be used for in situ measurements with a high spectral and spatial resolution in terrestrial and ice ecosystems and is based on the Laser-Induced Fluorescence Emission (L.I.F.E.) technique. Photoautotrophic supraglacial communities can be identified by the detection of L.I.F.E. signatures in photopigments. The L.I.F.E. instrument calibration for the porphyrin derivates chlorophylla (chla) (405 nm laser excitation) and B-phycoerythrin (B-PE) (532 nm laser excitation) is demonstrated. For the validation of this methodology, L.I.F.E. data were ratified by a conventional method for chla quantification that involved pigment extraction and subsequent absorption spectroscopy. The prototype applicability in the field was proven in extreme polar environments. Further testing on terrestrial habitats took place during Mars analog simulations in the Moroccan dessert and on an Austrian rock glacier. The L.I.F.E. instrument enables high resolution scans of large areas with acceptable operation logistics and contributes to a better understanding of the ecological potential of supraglacial communities in the context of global change.


Assuntos
Biomarcadores/metabolismo , Fluorescência , Aquecimento Global , Camada de Gelo/química , Lasers/normas
20.
Nat Commun ; 10(1): 5261, 2019 11 20.
Artigo em Inglês | MEDLINE | ID: mdl-31748607

RESUMO

Marine phytoplankton growth at high latitudes is extensively limited by iron availability. Icebergs are a vector transporting the bioessential micronutrient iron into polar oceans. Therefore, increasing iceberg fluxes due to global warming have the potential to increase marine productivity and carbon export, creating a negative climate feedback. However, the magnitude of the iceberg iron flux, the subsequent fertilization effect and the resultant carbon export have not been quantified. Using a global analysis of iceberg samples, we reveal that iceberg iron concentrations vary over 6 orders of magnitude. Our results demonstrate that, whilst icebergs are the largest source of iron to the polar oceans, the heterogeneous iron distribution within ice moderates iron delivery to offshore waters and likely also affects the subsequent ocean iron enrichment. Future marine productivity may therefore be not only sensitive to increasing total iceberg fluxes, but also to changing iceberg properties, internal sediment distribution and melt dynamics.


Assuntos
Camada de Gelo/química , Ferro/análise , Regiões Antárticas , Regiões Árticas , Argentina , Carbono/metabolismo , Chile , Congelamento , Sedimentos Geológicos/análise , Sedimentos Geológicos/química , Aquecimento Global , Groenlândia , Islândia , Ferro/metabolismo , Oceanos e Mares , Fitoplâncton/metabolismo , Água do Mar/análise , Água do Mar/química , Svalbard
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