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1.
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
2.
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
3.
Mar Pollut Bull ; 145: 306-315, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31590792

RESUMO

Understanding the fate of spilled oil in cold environments is essential for oil spill response in Arctic areas. The potential for oils to adhere to sea ice and mechanical skimmers can significantly impact the success of oil spill response and influence the fate of oil in the marine environment. Therefore, the affinity of oil to sea ice and skimmer material was quantified experimentally for three different types of oils at various degrees of weathering. Contact angle measurements of crude oil droplets were performed on the top of and under sea ice and polyethylene-based skimmer material, being submerged in seawater (-2 °C). In addition, "dip- and refloat" tests were performed to quantify the adhesion and study the re-floating process of oil from sea ice at -2 °C (moist ice) and -20 °C (cold dry ice), and from a skimmer material prior to and subsequently to its submersion in seawater (-2 °C). The results indicated limited interaction of oils with sea ice submerged in seawater, but a strong affinity of oils towards polyethylene-based skimmer material.


Assuntos
Camada de Gelo/química , Petróleo , Polietileno/química , Água do Mar/química , Poluentes Químicos da Água/química , Regiões Árticas , Poluição por Petróleo/análise
4.
Mar Pollut Bull ; 145: 463-473, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31590811

RESUMO

Microplastics (plastic particles <5 mm) are an emerging concern in Arctic sea ice with measured concentrations orders of magnitude higher than in surface seawater. However, incorporation of microplastics into sea ice, and their impact on sea ice properties, is unknown. We added microplastic particles in a microcosm experiment to determine microplastic distributions and effects on sea ice properties. Microplastic additions did not affect sea ice growth, but high concentrations of microplastics at the ice surface resulted in high ice salinity and changes in sea ice albedo. Field studies in the Gulf of Bothnia (Baltic Sea) showed sea ice concentration of microplastics from 8 to 41 particles per liter of melted ice, wich were much lower than those found to impact sea ice properties in the microcosm experiments. However, should microplastic concentrations increase, microplastic incorporation in sea ice may impact sea ice albedo.


Assuntos
Camada de Gelo/química , Plásticos/análise , Água do Mar/análise , Regiões Árticas , Países Bálticos , Monitoramento Ambiental , Poluentes Químicos da Água/análise
5.
Nature ; 574(7777): 237-241, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31578526

RESUMO

Earth is heading towards a climate that last existed more than three million years ago (Ma) during the 'mid-Pliocene warm period'1, when atmospheric carbon dioxide concentrations were about 400 parts per million, global sea level oscillated in response to orbital forcing2,3 and peak global-mean sea level (GMSL) may have reached about 20 metres above the present-day value4,5. For sea-level rise of this magnitude, extensive retreat or collapse of the Greenland, West Antarctic and marine-based sectors of the East Antarctic ice sheets is required. Yet the relative amplitude of sea-level variations within glacial-interglacial cycles remains poorly constrained. To address this, we calibrate a theoretical relationship between modern sediment transport by waves and water depth, and then apply the technique to grain size in a continuous 800-metre-thick Pliocene sequence of shallow-marine sediments from Whanganui Basin, New Zealand. Water-depth variations obtained in this way, after corrections for tectonic subsidence, yield cyclic relative sea-level (RSL) variations. Here we show that sea level varied on average by 13 ± 5 metres over glacial-interglacial cycles during the middle-to-late Pliocene (about 3.3-2.5 Ma). The resulting record is independent of the global ice volume proxy3 (as derived from the deep-ocean oxygen isotope record) and sea-level cycles are in phase with 20-thousand-year (kyr) periodic changes in insolation over Antarctica, paced by eccentricity-modulated orbital precession6 between 3.3 and 2.7 Ma. Thereafter, sea-level fluctuations are paced by the 41-kyr period of cycles in Earth's axial tilt as ice sheets stabilize on Antarctica and intensify in the Northern Hemisphere3,6. Strictly, we provide the amplitude of RSL change, rather than absolute GMSL change. However, simulations of RSL change based on glacio-isostatic adjustment show that our record approximates eustatic sea level, defined here as GMSL unregistered to the centre of the Earth. Nonetheless, under conservative assumptions, our estimates limit maximum Pliocene sea-level rise to less than 25 metres and provide new constraints on polar ice-volume variability under the climate conditions predicted for this century.


Assuntos
Água do Mar/análise , Dióxido de Carbono/análise , Foraminíferos/química , Sedimentos Geológicos/química , História Antiga , Camada de Gelo/química , Nova Zelândia , Oceanos e Mares , Isótopos de Oxigênio/análise , Pressão Parcial
7.
Nature ; 574(7777): 233-236, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31471591

RESUMO

Reconstructing the evolution of sea level during past warmer epochs such as the Pliocene provides insight into the response of sea level and ice sheets to prolonged warming1. Although estimates of the global mean sea level (GMSL) during this time do exist, they vary by several tens of metres2-4, hindering the assessment of past and future ice-sheet stability. Here we show that during the mid-Piacenzian Warm Period, which was on average two to three degrees Celsius warmer than the pre-industrial period5, the GMSL was about 16.2 metres higher than today owing to global ice-volume changes, and around 17.4 metres when thermal expansion of the oceans is included. During the even warmer Pliocene Climatic Optimum (about four degrees Celsius warmer than pre-industrial levels)6, our results show that the GMSL was 23.5 metres above the present level, with an additional 1.6 metres from thermal expansion. We provide six GMSL data points, ranging from 4.39 to 3.27 million years ago, that are based on phreatic overgrowths on speleothems from the western Mediterranean (Mallorca, Spain). This record is unique owing to its clear relationship to sea level, its reliable U-Pb ages and its long timespan, which allows us to quantify uncertainties on potential uplift. Our data indicate that ice sheets are very sensitive to warming and provide important calibration targets for future ice-sheet models7.


Assuntos
Mudança Climática/história , Água do Mar/análise , Calibragem , Dióxido de Carbono/análise , Foraminíferos/química , História Antiga , Camada de Gelo/química , Ilhas , Mar Mediterrâneo , Isótopos de Oxigênio/análise , Espanha , Incerteza
8.
J Environ Radioact ; 208-209: 106039, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31491585

RESUMO

An alpine ice core, extracted from the Adamello glacier (Central Italian Alps), was analyzed in its entire length through low background γ-spectroscopy, for the detection of 137Cs. Our results show that in glacier ice 137Cs is tightly bound to insoluble particulate matter inside the ice core, and it is therefore possible to restrict γ-spectroscopy analysis to particulate matter only. We show how the sensibility of the detection limit can be improved by almost one order of magnitude by using a well-type detector instead of a coaxial one. Hypothesis on the dating of some radioactive layers are also hereby presented.


Assuntos
Radioisótopos de Césio/análise , Camada de Gelo/química , Monitoramento de Radiação , Poluentes Radioativos/análise , Itália
9.
Environ Pollut ; 254(Pt A): 112974, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31376600

RESUMO

Moss is usually as an initial colonizer in alpine glacier retreated regions. We hypothesized that moss can significantly facilitate the toxic metals accumulation in alpine ecosystems based on its strong ability of absorption and the role in soil development. Hence, we investigated the trace element pool sizes and enrichment factors, especially for mercury (Hg) by using the Hg isotopic compositions to determine the source contributions in a moss-dominated ecosystem over glacial erratic in Eastern Tibetan Plateau. Results show that Hg, lead (Pb) and cadmium (Cd) are highly enriched in organic soils. Specifically, Cd concentration is 5-20 times higher than the safety limit of the acid soil (pH ≤ 5.5) in China. Atmospheric depositions dominantly contribute to the Pb and Cd sources in organic soils, and followed by the moraine particles influences. The lowering pH in organic soils increasing with glacial retreated time results in the desorption of Cd in organic soils. Atmospheric Hg0 uptake by moss predominantly contributes to the Hg sources in organic soils. The average Pb accumulation rate over last 125-year is about 5.6 ±â€¯1.0 mg m-2 yr-1, and for Cd is 0.4 ±â€¯0.1 mg m-2 yr-1, and for Hg0 is 27.6 ±â€¯3.2 µg m-2 yr-1. These elevated accumulation rates are caused by the high moss biomass and elevated atmospheric Hg, Pb and Cd pollution levels in China and neighbouring regions. Our study indicates that the moss not only as the bioindicator, but also plays an important role in the hazardous metal biogeochemical cycling in alpine regions.


Assuntos
Briófitas/metabolismo , Cádmio/análise , Monitoramento Ambiental/métodos , Chumbo/análise , Mercúrio/análise , Poluentes do Solo/análise , Biodegradação Ambiental , China , Ecossistema , Poluição Ambiental/análise , Camada de Gelo/química , Metais Pesados/análise , Solo/química , Oligoelementos/análise
10.
Nature ; 571(7763): 99-102, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31270485

RESUMO

The long-term cooling, decline in the partial pressure of carbon dioxide, and the establishment of permanent polar ice sheets during the Neogene period1,2 have frequently been attributed to increased uplift and erosion of mountains and consequent increases in silicate weathering, which removes atmospheric carbon dioxide3,4. However, geological records of erosion rates are potentially subject to averaging biases5,6, and the magnitude of the increase in weathering fluxes-and even its existence-remain debated7-9. Moreover, an increase in weathering scaled to the proposed erosional increase would have removed nearly all carbon from the atmosphere10, which has led to suggestions of compensatory carbon fluxes11-13 in order to preserve mass balance in the carbon cycle. Alternatively, an increase in land surface reactivity-resulting from greater fresh-mineral surface area or an increase in the supply of reactive minerals-rather than an increase in the weathering flux, has been proposed to reconcile these disparate views8,9. Here we use a parsimonious carbon cycle model that tracks two weathering-sensitive isotopic tracers (stable 7Li/6Li and cosmogenic 10Be/9Be) to show that an increase in land surface reactivity is necessary to simultaneously decrease atmospheric carbon dioxide, increase seawater 7Li/6Li and retain constant seawater 10Be/9Be over the past 16 million years. We find that the global silicate weathering flux remained constant, even as the global silicate weathering intensity-the fraction of the total denudation flux that is derived from silicate weathering-decreased, sustained by an increase in erosion. Long-term cooling during the Neogene thus reflects a change in the partitioning of denudation into weathering and erosion. Variable partitioning of denudation and consequent changes in silicate weathering intensity reconcile marine isotope and erosion records with the need to maintain mass balance in the carbon cycle and without requiring increases in the silicate weathering flux.


Assuntos
Atmosfera/química , Ciclo do Carbono , Dióxido de Carbono/análise , Dióxido de Carbono/história , Temperatura Baixa , Sedimentos Geológicos/química , Geologia/história , Retroalimentação , Sedimentos Geológicos/análise , História Antiga , Camada de Gelo/química , Modelos Teóricos , Rios/química , Água do Mar/química , Silicatos/análise
11.
Ecotoxicol Environ Saf ; 181: 11-17, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31154115

RESUMO

Numerous chemicals have been manufactured through industrial activities and used as consumer products since the late 18th century. Non-target analysis is a new analytical tool to detect many chemicals in environmental samples and to prioritize emerging contaminants. In this study, suspect and non-target analytical methods were optimized using gas chromatography coupled with time-of-flight (GC/TOF) to propose contaminants of emerging concern for the Arctic environment. A suspect analytical method was developed with qualification and qualifier ions, isotopic ratios, and retention times of 215 contaminants including persistent organic pollutants (POPs) to establish an in-house library. Non-target analytical method was also optimized with a deconvoluted ion chromatogram, which is a form that can possibly match the mass spectrum of the NIST library. Multiple environmental samples, such as seawater, air, soil, sediment, sludge, and iceberg, collected from the Arctic region were analyzed with suspect and non-target analysis of GC/TOF after the clean-up procedure with a solid phase extraction (SPE) cartridge. The commonly detected contaminants in the Arctic environmental samples were siloxanes, organophosphate flame retardants, phthalates, synthetic musk compounds, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons. Among them, siloxanes and organophosphate flame retardants were proposed to be contaminants of emerging concerns for the Arctic environment. This is the first report to prioritize emerging contaminants in the Arctic environment with suspect and non-target analysis of GC/TOF.


Assuntos
Monitoramento Ambiental/métodos , Poluentes Ambientais/análise , Retardadores de Chama/análise , Bifenilos Policlorados/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Siloxanas/análise , Regiões Árticas , Cromatografia Gasosa , Monitoramento Ambiental/instrumentação , Camada de Gelo/química , Espectrometria de Massas , Água do Mar/química , Solo/química , Extração em Fase Sólida
12.
Mar Pollut Bull ; 144: 160-166, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31179983

RESUMO

Mobile nuclear magnetic resonance (NMR) operating in Earth's magnetic field is adapted to detect leaked or spilled oil trapped in or under sea ice without the need to place any personnel on the ice. A helicopter placed a 6-meter diameter NMR coil system weighing approximately 1000 kg on 92 cm-thick ice surrogate and detected the equivalent of 1 cm thick oil under the ice surrogate in 3-1/2 min.


Assuntos
Aeronaves , Monitoramento Ambiental/métodos , Camada de Gelo/química , Espectroscopia de Ressonância Magnética , Poluição por Petróleo/análise , Tecnologia de Sensoriamento Remoto/métodos , Monitoramento Ambiental/instrumentação , Desenho de Equipamento , Terra Nova e Labrador , Tecnologia de Sensoriamento Remoto/instrumentação
13.
Environ Sci Process Impacts ; 21(7): 1076-1084, 2019 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-31241094

RESUMO

Dissolved organic matter (DOM) is a common solute in snow and ice at Earth's surface. Its effects on reaction kinetics in ice and at air-ice interfaces can be large, but are currently difficult to quantify. We used Raman microscopy to characterize the surface and bulk of frozen aqueous solutions containing humic acid, sodium dodecyl sulfate (SDS), and citric acid at a range of concentrations and temperatures. The surface-active species (humic acid and SDS) were distributed differently than citric acid. Humic acid and SDS are almost completely excluded to the air-ice interface during freezing, where they form a film that coats the surface nearly completely. A liquid layer that coats the majority of the surface was observed at all humic acid and SDS concentrations. Citric acid, which is smaller and less surface active, is excluded to liquid channels at the air-ice interface and within the ice bulk, as has previously been reported for ionic solutes such as sodium chloride. Incomplete surface wetting was observed at all citric acid concentrations and at all temperatures (up to -5 °C). Citric acid appears to be solvated in frozen samples, but SDS and humic acid do not. These results will improve our understanding of the effects of organic solutes on environmental and atmospheric chemistry within ice and at air-ice interfaces.


Assuntos
Ar/análise , Substâncias Húmicas/análise , Camada de Gelo/química , Ácido Cítrico/análise , Temperatura Baixa , Congelamento , Cinética , Modelos Teóricos , Dodecilsulfato de Sódio/análise , Solubilidade , Soluções , Análise Espectral Raman , Tensoativos/análise
14.
Environ Sci Pollut Res Int ; 26(23): 23645-23660, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31203542

RESUMO

Glacier runoff shows significant change under global warming in the headwater region of the Indus River with great impact on its highly populated downstream area, but the hydrochemistry characteristics of meltwater and the changing mechanism remain unclear in this region. In this study, runoff water samples were collected during May and June, 2015, from four glacial catchments in the Upper Indus Basin to investigate general characteristics and daytime dynamics of meltwater runoff together with sediment and chemical contents. Results showed that glacier runoff in the studied area had an alkaline pH and much higher sediment yields than the local average of the non-glacier areas. The carbonate-dominated geological feature in the four catchments resulted in single chemical facies of Ca-HCO3. The dominant process determining the glacier runoff chemistry was rock-water interaction, with less soluble minerals and less intensive evaporate weathering in the Passu and Gulmit catchments than the B&B and Hinarchi catchments. Comparing the investigated catchments, the larger glacier with longer flow path exhibited higher runoff but lower melting rate, higher SSC resulting from higher erosive power of flow, and higher solute concentrations as a consequence of more intensive contact of meltwater with rock minerals along the longer flow path. For individual catchments, a negative correlation between TDS and flow rate (R2 = 0.26~0.53) and changing trends of ion ratios with flow rate demonstrated that under intensive melting conditions, rock-water interactions were reduced, resulting in dilution of solutes. Overall, the general chemical characteristics of the investigated glacier runoff indicated geological control, whereas individual glacier illustrated hydrological control on the daytime dynamics of glacier runoff chemistry. The presence of glacier terminal lake and agriculture land can significantly alter the hydrochemistry of downstream runoff.


Assuntos
Monitoramento Ambiental , Camada de Gelo/química , Rios/química , Poluentes da Água/análise , Carbonatos/análise , Hidrologia , Água/química , Movimentos da Água , Tempo (Meteorologia)
15.
Environ Pollut ; 250: 762-772, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31035159

RESUMO

To differentiate the source of aeolian dust between the desert sources from Pan-third pole and high mountain glaciers, therefore, we investigated the spatial variability of aeolian dust sources in the Pan-third polar region. The question of whether such changes reflect variable transport pathways from a unique source in the western China area was addressed. That is, the SrNd radiogenic isotope composition of modern desert samples do not support the hypothesis of a single dust provenance at higher elevation mountain glaciers by long-distance transport; regional sources also play a significant role. Based on previous studies and the data from this study, the five isotopic regions were divided, which are controlled by the geological characteristics in western China. The results suggest that mineral dust deposited into the high-mountain glaciers originated from the free ice region because of glacier melting and the physical and chemical erosion of rocks from the surrounding mountains by local wind systems. The Pb isotopic data further demonstrated that natural dust is the source of Pb for the high-mountain glaciers of Pan-third pole. These results provide an exhaustive documentation of the isotopic signature of the regional dust reaching the glacier regions.


Assuntos
Altitude , Poeira/análise , Monitoramento Ambiental/métodos , Camada de Gelo/química , Vento , China , Isótopos/análise
16.
Environ Pollut ; 248: 659-666, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30849583

RESUMO

We analysed the spatial and temporal distribution of a selection of pesticides in Alpine glaciers used on the Po Plain in Northern Italy, near the Alps. By analysing a 102-m ice core taken from the Lys Glacier (Monte Rosa massif, Italy), we highlight historical contamination from the insecticide chlorpyrifos and the herbicide terbuthylazine, confirming the role of alpine glaciers as temporal sinks. In addition, we collected meltwater samples from six glaciers distributed along the Alpine Arc during the summer of 2016, which showed widespread contamination by pesticides. Overall, chlorpyrifos and terbuthylazine dominated the contaminant fingerprint of all of the studied glaciers, with contamination peaks occurring at the beginning of the melting season. This highlights the importance of the medium-range atmospheric transport of these pesticides in connection with agricultural practices in the areas beneath the Italian Alps, where they are widely applied. The release of pesticides in meltwater can lead to potential risks to the aquatic ecosystems of headwater streams, as we demonstrate for chlorpyrifos. This suggests that the medium-range atmospheric transport of pesticides should be considered as part of regulations to protect the water quality of these pristine environments.


Assuntos
Monitoramento Ambiental/métodos , Camada de Gelo/química , Praguicidas/análise , Rios/química , Poluentes Químicos da Água/análise , Altitude , Ecossistema , Itália , Medição de Risco , Estações do Ano , Análise Espaço-Temporal
17.
Environ Monit Assess ; 191(4): 213, 2019 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-30852667

RESUMO

Snowpack and glacial melt samples were collected to understand the hydrochemical, isotopic characteristics and the source of Hg contamination in high altitude glacierized Himalayan catchment. Both the snow and glacial melt were acidic in nature with calcium and magnesium as the dominant cations and bicarbonate and chloride as the dominant anions. The major ion concentrations for cations were found to be Ca2+ > Mg2+ > Na+ > K+ and HCO3- > Cl- > SO42- > NO3- for anions. The atmospheric processes like the precipitation source and aerosol scavenging control the snow chemistry and the weathering of the rocks modify the hydrochemistry of glacial melt. The samples of both the snow and glacial melt were classified as Ca-Mg-HCO3- type. The concentration of Hg in snow (154.95 ng L-1) and glacial melt (112.04 ng L-1) was highest (still lower compared to the maximum permissible limit (1000 ng L-1) by WHO in drinking water) during summer season (August-September) and lowest (snow 2.2 and 40.01 ng L-1 for glacial melt) during winter (November). The results reveal that mercury concentration in snowpacks is attributed to the combined mixing of long-range transport of pollutants via westerlies throughout the year and the industrial effluents coming from highly industrial belts of Panjab, Haryana, Rajasthan, Indo-Gangetic plains, and neighboring areas via southwest monsoons during August-September. However, in glacial melt, the Hg concentration was typically controlled by rate of melting, leaching, and percolation. Higher degree and rate of glacial melting decreases the Hg concentration in glacial melt. Stable isotopic analysis and backward air mass trajectory modeling also corroborate the source of precipitation from southwest monsoons during August-September, with its air mass trajectories passing through the highly industrialized belts of Indo-Gangetic plain and adjoining areas.


Assuntos
Altitude , Monitoramento Ambiental/métodos , Camada de Gelo/química , Mercúrio/análise , Neve/química , Poluentes Químicos da Água/análise , Índia , Íons/análise , Estações do Ano , Tempo (Meteorologia)
18.
Photochem Photobiol Sci ; 18(3): 717-746, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30810561

RESUMO

This assessment summarises the current state of knowledge on the interactive effects of ozone depletion and climate change on aquatic ecosystems, focusing on how these affect exposures to UV radiation in both inland and oceanic waters. The ways in which stratospheric ozone depletion is directly altering climate in the southern hemisphere and the consequent extensive effects on aquatic ecosystems are also addressed. The primary objective is to synthesise novel findings over the past four years in the context of the existing understanding of ecosystem response to UV radiation and the interactive effects of climate change. If it were not for the Montreal Protocol, stratospheric ozone depletion would have led to high levels of exposure to solar UV radiation with much stronger negative effects on all trophic levels in aquatic ecosystems than currently experienced in both inland and oceanic waters. This "world avoided" scenario that has curtailed ozone depletion, means that climate change and other environmental variables will play the primary role in regulating the exposure of aquatic organisms to solar UV radiation. Reductions in the thickness and duration of snow and ice cover are increasing the levels of exposure of aquatic organisms to UV radiation. Climate change was also expected to increase exposure by causing shallow mixed layers, but new data show deepening in some regions and shoaling in others. In contrast, climate-change related increases in heavy precipitation and melting of glaciers and permafrost are increasing the concentration and colour of UV-absorbing dissolved organic matter (DOM) and particulates. This is leading to the "browning" of many inland and coastal waters, with consequent loss of the valuable ecosystem service in which solar UV radiation disinfects surface waters of parasites and pathogens. Many organisms can reduce damage due to exposure to UV radiation through behavioural avoidance, photoprotection, and photoenzymatic repair, but meta-analyses continue to confirm negative effects of UV radiation across all trophic levels. Modeling studies estimating photoinhibition of primary production in parts of the Pacific Ocean have demonstrated that the UV radiation component of sunlight leads to a 20% decrease in estimates of primary productivity. Exposure to UV radiation can also lead to positive effects on some organisms by damaging less UV-tolerant predators, competitors, and pathogens. UV radiation also contributes to the formation of microplastic pollutants and interacts with artificial sunscreens and other pollutants with adverse effects on aquatic ecosystems. Exposure to UV-B radiation can decrease the toxicity of some pollutants such as methyl mercury (due to its role in demethylation) but increase the toxicity of other pollutants such as some pesticides and polycyclic aromatic hydrocarbons. Feeding on microplastics by zooplankton can lead to bioaccumulation in fish. Microplastics are found in up to 20% of fish marketed for human consumption, potentially threatening food security. Depletion of stratospheric ozone has altered climate in the southern hemisphere in ways that have increased oceanic productivity and consequently the growth, survival and reproduction of many sea birds and mammals. In contrast, warmer sea surface temperatures related to these climate shifts are also correlated with declines in both kelp beds in Tasmania and corals in Brazil. This assessment demonstrates that knowledge of the interactive effects of ozone depletion, UV radiation, and climate change factors on aquatic ecosystems has advanced considerably over the past four years and confirms the importance of considering synergies between environmental factors.


Assuntos
Adaptação Biológica , Organismos Aquáticos/fisiologia , Mudança Climática , Perda de Ozônio , Raios Ultravioleta , Animais , Aquicultura , Organismos Aquáticos/efeitos da radiação , Ecossistema , Poluição Ambiental/efeitos adversos , Poluição Ambiental/análise , Peixes/fisiologia , Água Doce/análise , Camada de Gelo/química , Oceanos e Mares , Fotossíntese , Ozônio Estratosférico/análise , Raios Ultravioleta/efeitos adversos , Zooplâncton/fisiologia
19.
Photochem Photobiol Sci ; 18(3): 747-774, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30810562

RESUMO

Global change influences biogeochemical cycles within and between environmental compartments (i.e., the cryosphere, terrestrial and aquatic ecosystems, and the atmosphere). A major effect of global change on carbon cycling is altered exposure of natural organic matter (NOM) to solar radiation, particularly solar UV radiation. In terrestrial and aquatic ecosystems, NOM is degraded by UV and visible radiation, resulting in the emission of carbon dioxide (CO2) and carbon monoxide, as well as a range of products that can be more easily degraded by microbes (photofacilitation). On land, droughts and land-use change can reduce plant cover causing an increase in exposure of plant litter to solar radiation. The altered transport of soil organic matter from terrestrial to aquatic ecosystems also can enhance exposure of NOM to solar radiation. An increase in emission of CO2 from terrestrial and aquatic ecosystems due to the effects of global warming, such as droughts and thawing of permafrost soils, fuels a positive feedback on global warming. This is also the case for greenhouse gases other than CO2, including methane and nitrous oxide, that are emitted from terrestrial and aquatic ecosystems. These trace gases also have indirect or direct impacts on stratospheric ozone concentrations. The interactive effects of UV radiation and climate change greatly alter the fate of synthetic and biological contaminants. Contaminants are degraded or inactivated by direct and indirect photochemical reactions. The balance between direct and indirect photodegradation or photoinactivation of contaminants is likely to change with future changes in stratospheric ozone, and with changes in runoff of coloured dissolved organic matter due to climate and land-use changes.


Assuntos
Atmosfera/análise , Mudança Climática , Ozônio Estratosférico/análise , Raios Ultravioleta , Animais , Regiões Árticas , Carbono/análise , Dióxido de Carbono/análise , Secas , Ecossistema , Poluentes Ambientais/análise , Água Doce/análise , Aquecimento Global , Efeito Estufa , Gases de Efeito Estufa/análise , Camada de Gelo/química , Recursos Naturais , Oceanos e Mares , Perda de Ozônio , Fotólise , Energia Solar
20.
Photochem Photobiol Sci ; 18(3): 602-640, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30810565

RESUMO

This report assesses the effects of stratospheric ozone depletion and anticipated ozone recovery on the intensity of ultraviolet (UV) radiation at the Earth's surface. Interactions between changes in ozone and changes in climate, as well as their effects on UV radiation, are also considered. These evaluations focus mainly on new knowledge gained from research conducted during the last four years. Furthermore, drivers of changes in UV radiation other than ozone are discussed and their relative importance is assessed. The most important of these factors, namely clouds, aerosols and surface reflectivity, are related to changes in climate, and some of their effects on short- and long-term variations of UV radiation have already been identified from measurements. Finally, projected future developments in stratospheric ozone, climate, and other factors affecting UV radiation have been used to estimate changes in solar UV radiation from the present to the end of the 21st century. New instruments and methods have been assessed with respect to their ability to provide useful and accurate information for monitoring solar UV radiation at the Earth's surface and for determining relevant exposures of humans. Evidence since the last assessment reconfirms that systematic and accurate long-term measurements of UV radiation and stratospheric ozone are essential for assessing the effectiveness of the Montreal Protocol and its Amendments and adjustments. Finally, we have assessed aspects of UV radiation related to biological effects and human health, as well as implications for UV radiation from possible solar radiation management (geoengineering) methods to mitigate climate change.


Assuntos
Mudança Climática , Ozônio Estratosférico/análise , Raios Ultravioleta , Regiões Antárticas , Clima , Humanos , Camada de Gelo/química , Oceanos e Mares , Luz Solar
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