Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 13.887
Filtrar
1.
Rev Environ Contam Toxicol ; 248: 111-189, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-30671689

RESUMO

Metal-rich sediments have the potential to impair life in freshwater streams and rivers and, thereby, to inhibit recovery of ecological conditions after any remediation of mine water discharges. Sediments remain metal-rich over long time periods and have long-term potential ecotoxicological interactions with local biota, unless the sediments themselves are physically removed or replaced by less metal-rich sediment. Laboratory-derived environmental quality standards are difficult to apply to the field situation, as many complicating factors exist in the real world. Therefore, there is a strong case to consider other, field-relevant, measures of toxic effects as alternatives to laboratory-derived standards and to seek better biological tools to detect, diagnose and ideally predict community-level ecotoxicological impairment. Hence, this review concentrated on field measures of toxic effects of metal-rich sediment in freshwater streams, with less emphasis on laboratory-based toxicity testing approaches. To this end, this review provides an overview of the impact of metal-rich sediments on freshwater stream life, focusing on biological impacts linked to metal contamination.


Assuntos
Monitoramento Ambiental , Metais/análise , Mineração , Rios , Poluentes Químicos da Água/análise , Água Doce , Sedimentos Geológicos/química
2.
J Environ Sci (China) ; 85: 156-167, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31471022

RESUMO

This study evaluated uranium sequestration performance in iron-rich (30 g/kg) sediment via bioreduction followed by reoxidation. Field tests (1383 days) at Oak Ridge, Tennessee demonstrated that uranium contents in sediments increased after bioreduced sediments were re-exposed to nitrate and oxygen in contaminated groundwater. Bioreduction of contaminated sediments (1200 mg/kg U) with ethanol in microcosm reduced aqueous U from 0.37 to 0.023 mg/L. Aliquots of the bioreduced sediment were reoxidized with O2, H2O2, and NaNO3, respectively, over 285 days, resulting in aqueous U of 0.024, 1.58 and 14.4 mg/L at pH 6.30, 6.63 and 7.62, respectively. The source- and the three reoxidized sediments showed different desorption and adsorption behaviors of U, but all fit a Freundlich model. The adsorption capacities increased sharply at pH 4.5 to 5.5, plateaued at pH 5.5 to 7.0, then decreased sharply as pH increased from 7.0 to 8.0. The O2-reoxidized sediment retained a lower desorption efficiency at pH over 6.0. The NO3--reoxidized sediment exhibited higher adsorption capacity at pH 5.5 to 6.0. The pH-dependent adsorption onto Fe(III) oxides and formation of U coated particles and precipitates resulted in U sequestration, and bioreduction followed by reoxidation can enhance the U sequestration in sediment.


Assuntos
Biodegradação Ambiental , Poluentes Radioativos do Solo/metabolismo , Urânio/metabolismo , Sedimentos Geológicos/química , Poluentes Radioativos do Solo/química , Tennessee , Urânio/química
3.
Sci Total Environ ; 690: 1131-1139, 2019 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-31470476

RESUMO

Dissolved organic carbon (DOC) turnover in aquatic environments is modulated by the presence of other key macronutrients, including nitrogen (N) and phosphorus (P). The ratio of these nutrients directly affects the rates of microbial growth and nutrient processing in the natural environment. The aim of this study was to investigate how labile DOC metabolism responds to changes in nutrient stoichiometry using 14C tracers in conjunction with untargeted analysis of the primary metabolome in upland peat river sediments. N addition led to an increase in 14C-glucose uptake, indicating that the sediments were likely to be primarily N limited. The mineralisation of glucose to 14CO2 reduced following N addition, indicating that nutrient addition induced shifts in internal carbon (C) partitioning and microbial C use efficiency (CUE). This is directly supported by the metabolomic profile data which identified significant differences in 22 known metabolites (34% of the total) and 30 unknown metabolites (16% of the total) upon the addition of either N or P. 14C-glucose addition increased the production of organic acids known to be involved in mineral P dissolution (e.g. gluconic acid, malic acid). Conversely, when N was not added, the addition of glucose led to the production of the sugar alcohols, mannitol and sorbitol, which are well known microbial C storage compounds. P addition resulted in increased levels of several amino acids (e.g. alanine, glycine) which may reflect greater rates of microbial growth or the P requirement for coenzymes required for amino acid synthesis. We conclude that inorganic nutrient enrichment in addition to labile C inputs has the potential to substantially alter in-stream biogeochemical cycling in oligotrophic freshwaters.


Assuntos
Monitoramento Ambiental , Sedimentos Geológicos/química , Poluentes da Água/análise , Carbono/análise , Água Doce/química , Nitrogênio/análise , Fósforo/análise
4.
Environ Monit Assess ; 191(10): 607, 2019 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-31485756

RESUMO

The geochemical fractions of heavy metals in sediments are crucial indexes for their mobility and bioavailability evaluations. However, different drying processes of sediment pretreatment could change metal geochemical fractions, especially for Hg, which is potentially volatile. In this study, the influence of pretreatment methods including oven-drying, air-drying, freeze-drying, and fresh sediments on the analysis of Hg fractions in sediments was investigated. Results showed that remarkable differences of Hg concentration were observed between fresh sediments and dried pretreatment sediments (P < 0.05). Briefly, the concentrations of the water-soluble and human stomach acid-soluble fractions in oven-dried and air-dried sediments generally showed significant increasing trends compared with those in the fresh sediments, while the organo-chelated fraction exhibited significant decreasing trends. The cause of this phenomenon was primarily the oxidation of organic matter, aging process, and the diffusion of Hg into micropores. The significant loss was also observed at elemental Hg fraction due to its volatilization effect. The freeze-drying posed minor influence on changes of Hg fraction analysis compared with oven-drying and air-drying. Moreover, the total Hg concentrations in pretreated sediments showed a decline of varying degrees compared with those in fresh sediments ascribing to the volatilization of elemental Hg. Finally, Pearson correlation analysis further confirmed that freeze-drying could minimize the errors of the Hg fraction analysis in sediments.


Assuntos
Dessecação , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Mercúrio/análise , Disponibilidade Biológica , Poluentes do Solo/análise , Volatilização
5.
Environ Monit Assess ; 191(9): 536, 2019 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-31377907

RESUMO

San Jorge Bay (23° S) is characterised by a permanent coastal upwelling front and a thermal front that influence water circulation into the bay. This bay constantly receives effluents from different mining activities. Several studies have demonstrated different levels of heavy metals in waters and sediments within the bay. The clam Protothaca thaca is a bivalve with sedentary habits, which is distributed along the Peruvian and Chilean coasts and is exploited commercially. During 2010, clams were collected inside the bay: north (La Chimba), centre (Paraíso) and south (Llacolén), as well as from a site outside the bay (Bolsico). Haematological parameters, condition factor index, lesions, parasites and pathogens and heavy metal concentrations in clam tissues were determined. The health indicators of clams inhabiting the bay varied between sites. Clams inside the bay showed higher prevalence and intensity of parasites and lesions than those clams inhabiting the site outside the bay, which could be indicating the presence of some environmental stressor (e.g. heavy metals). This study is the first to evaluate the health status of organisms from San Jorge Bay, and our results support the hypothesis that clams P. thaca can be used to evaluate environmental quality.


Assuntos
Bivalves/parasitologia , Monitoramento Ambiental , Sedimentos Geológicos/química , Metais Pesados/análise , Frutos do Mar , Poluentes Químicos da Água/análise , Animais , Baías , Chile , Meio Ambiente , Brânquias/parasitologia , Brânquias/patologia , Mineração , Parasitos
6.
Environ Monit Assess ; 191(8): 525, 2019 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-31363866

RESUMO

Arsenic contamination in marine environments is a serious issue because some arsenicals are very toxic, increasing the health risks associated with the consumption of marine products. This study describes the development of an improved rapid method for the quantification of arsenic species, including arsenite (AsIII), arsenate (AsV), arsenocholine (AsC), arsenobetaine (AsB), dimethylarsinic acid (DMA), and monomethyl arsonic acid (MMA), in seaweed, sediment, and seawater samples using high-performance liquid chromatography/inductively coupled plasma-mass spectrometry (HPLC/ICP-MS). ICP-MS based on dynamic reaction cells was used to eliminate spectral interference. Ammonium nitrate- and phosphate-based eluents were used as the mobile phases for HPLC analysis, leading to shorter overall retention time (6 min) and improved peak separation. Arsenicals were extracted with a 1% HNO3 solution that required no clean-up process and exhibited reasonable sensitivity and peak resolution. The optimized method was verified by applying it to hijiki seaweed certified reference material (CRM, NMIJ 7405-a) and to spiked blank samples of sediment and seawater. The proposed method measured the concentration of AsV in the CRM as 9.6 ± 0.6 µg/kg dry weight (dw), which is close to the certified concentration (10.1 ± 0.5 µg/kg dw). The recovery of the six arsenicals was 87-113% for the sediment and 99-101% for the seawater. In the analysis of real samples, AsV was the most abundant arsenical in hijiki and gulfweed, whereas AsB was dominant in other seaweed species. The two inorganic arsenicals (AsIII and AsV) and AsV were the most dominant in the sediment and seawater samples, respectively.


Assuntos
Arsenicais/análise , Cromatografia Líquida de Alta Pressão/métodos , Monitoramento Ambiental/métodos , Espectrometria de Massas/métodos , Poluentes Químicos da Água/análise , Monitoramento Ambiental/instrumentação , Sedimentos Geológicos/química , República da Coreia , Água do Mar/química , Alga Marinha/química
7.
Sci Total Environ ; 687: 907-916, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31412494

RESUMO

Mercury (Hg) is a global contaminant that poses a human health risk in its organic form, methylmercury (MeHg), through consumption of fish and fishery products. Bioaccumulation of Hg in the aquatic environment is controlled by a number of factors expected to be altered by climate change. We examined the individual and combined effects of temperature, sediment organic carbon, and salinity on the bioaccumulation of MeHg in an estuarine amphipod, Leptocheirus plumulosus, when exposed to sediment from two locations in the Gulf of Maine (Kittery and Bass Harbor) that contained different levels of MeHg and organic carbon. Higher temperatures and lower organic carbon levels individually increased uptake of MeHg by L. plumulosus as measured by the biota-sediment accumulation factor (BSAF), while the effect of salinity on BSAF differed by sediment source. Multi-factor statistical modeling using all data revealed a significant interaction between temperature and organic carbon for both sediments, in which increased temperature had a negative effect on BSAF at the lowest carbon levels and a positive effect at higher levels. Our results suggest that increased temperature and carbon loading, of a magnitude expected as a result from climate change, could be associated with a net decrease in amphipod BSAF of 50 to 71%, depending on sediment characteristics. While these are only first-order projections, our results indicate that the future fate of MeHg in marine food webs is likely to depend on a number of factors beyond Hg loading.


Assuntos
Anfípodes/metabolismo , Monitoramento Ambiental , Compostos de Metilmercúrio/metabolismo , Salinidade , Temperatura Ambiente , Poluentes Químicos da Água/metabolismo , Animais , Carbono , Estuários , Cadeia Alimentar , Sedimentos Geológicos/química
8.
Environ Pollut ; 253: 1117-1125, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31434189

RESUMO

Bed sediments and a dated sediment core were collected upstream and downstream from the city of Lyon (France) to assess the spatial and temporal trends of contamination by per- and polyfluoroalkyl substances (PFASs) in this section of the Rhône River. Upstream from Lyon, concentrations of total PFASs (ΣPFASs) in sediments are low (between 0.19 and 2.6 ng g-1 dry weight - dw), being characterized by a high proportion of perfluorooctane sulfonate (PFOS). Downstream from Lyon, and also from a fluoropolymer manufacturing plant, ΣPFASs concentrations reach 48.7 ng g-1 dw. A gradual decrease of concentrations is reported at the coring site further downstream (38 km). Based on a dated sediment core, the temporal evolution of PFASs is reconstructed from 1984 to 2013. Prior to 1987, ΣPFASs concentrations were low (≤2 ng g-1 dw), increasing to a maximum of 51 ng g-1 dw in the 1990s and then decreasing from 2002 to the present day (∼10 ng g-1 dw). In terms of the PFAS pattern, the proportion of perfluoroalkyl sulfonic acids (PFSAs) has remained stable since the 1980s (∼10%), whereas large variations are reported for carboxylic acids (PFCAs). Long chain- (C > 8) PFCAs characterized by an even number of perfluorinated carbons represent about 74% of the total PFAS load until 2005. However, from 2005 to 2013, the relative contribution of long chain- (C > 8) PFCAs with an odd number of perfluorinated carbons reaches 80%. Such changes in the PFAS pattern likely highlight a major shift in the industrial production process. This spatial and retrospective study provides valuable insights into the long-term contamination patterns of PFAS chemicals in river basins impacted by both urban and industrial activities.


Assuntos
Monitoramento Ambiental , Fluorcarbonetos/análise , Sedimentos Geológicos/química , Poluentes Químicos da Água/análise , Poluição Química da Água/estatística & dados numéricos , Ácidos Alcanossulfônicos , Ácidos Carboxílicos , França , Instalações Industriais e de Manufatura , Estudos Retrospectivos , Rios/química , Ácidos Sulfônicos/análise
9.
Environ Monit Assess ; 191(9): 570, 2019 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-31418096

RESUMO

Seasonal variations in mercury (Hg), cadmium (Cd), zinc (Zn), lead (Pb), arsenic (As), copper (Cu), and chromium (Cr) metal concentrations in 36 water and 36 sediment samples from River Tano were studied using Perkin Elmer atomic absorption spectrophotometer (AAS) between November 2016 and October 2017. Significantly higher metal concentrations were recorded in rainy season than dry season for both water and sediment except for Pb and Cd where sediment concentrations were higher in the dry season. Cu was detected only in the sediment samples. Spatially the source of the river is unpolluted for all the metals in both seasons but the midstream and downstream ends of the river were heavily polluted by Hg, Pb, and Cd. All the heavy metals studied except Zn exceeded the WHO standards for drinking water. In the sediment, Cd, Hg, and Cr concentrations exceeded the USEPA guidelines. Igeo and Concentration Factor analysis revealed unpolluted sediments in terms of Cu, Pb, As, and Cr. They were near the background concentrations but Hg and Cd were in the range of moderate to heavy pollution. All the metals correlated significantly among themselves to signify common source to the water. It thus remains risky to use untreated water from the midstream and downstream of River Tano for domestic purposes. Enforcement of the buffer zone policy is recommended to avert further deterioration of the river water and sediment qualities.


Assuntos
Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Metais Pesados/análise , Rios/química , Poluentes Químicos da Água/análise , Gana , Estações do Ano
10.
Environ Monit Assess ; 191(9): 552, 2019 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-31399843

RESUMO

The present work aims to observe the spatial distribution of metals associated with carbon forms (fraction < 2 mm) in surface sediments of two macrotidal estuaries, São Marcos Bay and Anil River Estuary, which are located within the transition region between the Amazonian and the semi-arid northeast regions. Grain size, metal content (Al, Fe, Mn, Cu, Pb, Cr, Zn, and Ni), organic matter, and calcium carbonate content were determined. Grain size analyses showed the predominance of the sand-sized fraction < 2 mm due to the local hydrodynamic conditions. Anil River Estuary sediments exhibited high organic matter content due to both the mangrove outwelling and domestic sewage discharge. They also presented high calcium carbonate content as a result of abundant remnants of gastropod shells. Organic matter acted as the primary geochemical carrier for most metals in both estuaries, while calcium carbonate acted as the secondary carrier. Enrichment factors indicated Mn sediment contamination in São Marcos Bay and Fe, Pb, and Zn contamination in the Anil River Estuary. These results also suggest that São Marcos Bay is influenced by harbor activities, mostly ore shipment, whereas Anil River Estuary sediments are enriched in these metals as a result of domestic and hospital effluents reaching the urbanized drainage basin.


Assuntos
Carbono/análise , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Metais Pesados/análise , Rios/química , Poluentes Químicos da Água/análise , Brasil , Carbonato de Cálcio/análise , Carbonatos/análise , Estuários
11.
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
12.
Sci Total Environ ; 691: 969-980, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31326819

RESUMO

A good understanding of lead (Pb) mobilization in eutrophic lakes is a key to the accurate assessment of Pb pollution. In this work, dissolved and labile Pb was determined by both high resolution dialysis (HR-Peeper) and diffusive gradients in thin films (DGT) in sediment-water profiles of the hyper-eutrophic Meiliang Bay of Lake Taihu on a monthly basis during one year. The drinking water standards for dissolved Pb of the World Health Organization (10µg/L) and those of China were exceeded in the overlying water (20.79-118.5µg/L). Out of which, a total of five months even exceeded the fisheries water quality limitation (50µg/L) in China. The algal blooms created an anaerobic environment in the surface sediments in July. The reductive conditions led to the dissolution of Fe/Mn and this caused the release of Pb, followed by organic matter complexation. This was supported by the coincident changes of dissolved Pb with dissolved organic matter (DOM) in sediments under anaerobic incubation. Algae residue decomposition in October caused another distinct release of Pb, but this process should be considerably suppressed by increased sulfide precipitation and pyrite adsorption of Pb ion. These results indicated that Pb mobilization in sediments can be significantly enhanced by algal blooms in eutrophic lakes, indicating that further attention should be paid to Pb pollution in waters with harmful algal blooms.


Assuntos
Sedimentos Geológicos/química , Proliferação Nociva de Algas , Chumbo/análise , Poluentes Químicos da Água/análise , China , Monitoramento Ambiental
13.
J Environ Radioact ; 208-209: 106016, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31325733

RESUMO

Theoretical and experimental studies have shown that activity concentrations of fallout radionuclides (such as 137Cs and excess 210Pb) decrease with particles size in aqueous suspensions. This paper is aimed at reviewing the theoretical fundamentals for granulometric speciation of radionuclides, and at exploring its practical use in the analytical context of gamma spectrometry for the radiometric dating of recent sediments, with view to: i) improving the detection of 137Cs (since its use as independent chronostratigraphic mark is challenging in the southern hemisphere because its low fallout rate), ii) supporting refined CIC models and normalization techniques in 210Pb-based radiogeochronologies. The work uses surface sediments sampled from the Tinto Estuary (SW Spain), affected by mining and phosphate-fertilizer industries, and from the Ankobra Estuary (Ghana), affected by intensive artisanal gold-mining. Granulometric classes have been separated by a sieving column with decreasing mesh sizes and the obtained cumulative percentage of mass mathematically described by a Rosin-Rammler particle-size distribution. The target radionuclides for gamma spectrometry were 210Pb, 226Ra and137Cs, complemented with 40K, 234Th and 228Ra. Results revealed that, far from ideal experiments, under actual environmental conditions the increase in activity concentrations with decreasing particle sizes is too moderate, and in general they are affected by larger counting uncertainties due to the small available amount of mass. Indeed, there was no correlation between grain-size and 137Cs concentrations (p = 0.25), and similarly for excess 210Pb (p = 0.53). No effect of the organic matter content was observed in 137Cs (p = 0.58) and excess 210Pb (p = 0.85) concentrations. Present results pose some concerns to the general use of granulometric speciation in the context of gamma spectrometry for supporting the radiometric dating of recent sediments. A detailed discussion on the use of normalization methods is also presented.


Assuntos
Sedimentos Geológicos/química , Monitoramento de Radiação , Datação Radiométrica/métodos , Poluentes Radioativos da Água/análise , Gana , Mineração , Espanha , Espectrometria gama
14.
J Agric Food Chem ; 67(27): 7609-7615, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31257874

RESUMO

Shallow water systems are uniquely susceptible to environmental processes such as photolysis and hydrolysis that can influence the dissipation of pesticides into sediments. The fungicide dicloran has previously been shown to undergo photolysis and is reported to dissipate in soils and sediments. The photodegradation and dissipation of dicloran in freshwater and seawater was monitored in a laboratory-simulated shallow water system. While no difference was observed between freshwater and seawater systems in the presence of simulated sunlight, the dissipation of dicloran in dark trial systems differed between salinities; 30% of the applied mass dissipated into the sediment in freshwater vs 22% in seawater, and the photodegradation rate and half-life were also impacted by the presence of sediment. The potential for dicloran to dissipate and photodegrade affects the overall behavior of dicloran between waters. Differences in chemical behavior with sediment presence and potential for photodegradation have the capacity to impact organisms within the ecosystem and suggest that these factors may need to be implemented into chemical exposure assessments dependent upon location.


Assuntos
Compostos de Anilina/química , Água Doce/química , Sedimentos Geológicos/química , Fotólise , Água do Mar/química , Luz Solar , Ecossistema , Fungicidas Industriais/química , Solo/química , Poluentes Químicos da Água/química
15.
Environ Monit Assess ; 191(8): 485, 2019 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-31280379

RESUMO

The limited carrying capacities of shallow tropical lakes render them more vulnerable to ecological problems like eutrophication. Unregulated human activities such as unsustainable aquaculture and urbanization can alter ecosystem dynamics rapidly, and this warrants more comprehensive researches than what has been previously conducted. Here, we presented an integrated assessment of the nutrient dynamics, phytoplankton diversity, and sediment geochemistry in Lake Palakpakin, a shallow tropical lake of volcanic origin, to understand its deteriorating ecological state. Water, phytoplankton, and sediment samples were collected, and in situ water quality measurements were done during wet and dry seasons in four critical areas in the lake, namely, the inlet, center, sanctuary, and outlet. Results revealed that high light extinction coefficient (1.13 m-1), high turbidity (28 NTU), high phosphate concentration (> 2.0.5 mg/L), and the abundance of Microcystis aeruginosa, Anabaena helicoidea, and Lyngbya sp. indicate that from a relatively healthy lake in 2008, Lake Palakpakin has become a eutrophic to hypereutrophic freshwater body. High concentrations of available nutrients such as N and P were detected in the center and sanctuary sediments, which drive the internal nutrient loading in the lake. We recommend that management efforts be directed towards a whole-ecosystem approach in addressing the problem of eutrophication, especially in shallow tropical lakes.


Assuntos
Monitoramento Ambiental , Lagos/química , Fitoplâncton/crescimento & desenvolvimento , Biodiversidade , Conservação dos Recursos Naturais , Cianobactérias , Ecossistema , Eutrofização , Sedimentos Geológicos/química , Microcystis , Filipinas , Fósforo/análise , Estações do Ano , Poluentes da Água/análise , Qualidade da Água
16.
Environ Monit Assess ; 191(8): 522, 2019 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-31359154

RESUMO

Non-point source (NPS) pollution has been emerged as a major cause for reduced water quality of a lake due to increased human interference and disturbances in the natural condition of the surrounding catchment. The impact is, even more, worsening in the monsoon season when there is increased surface runoff. In the present study, an attempt has been made to predict the seasonal (monsoon) NPS loading in terms of sediment, nitrogen, and phosphorous in Maithon reservoir using Soil and Water Assessment Tool (SWAT) hydrologic model. The SWAT model was initially calibrated using monthly runoff and sediment yield data of monsoon period for the year 1998-2005 using observed data of Rajdhanwar station followed by its validation for the observed monthly runoff and sediment data from Giridih and Santrabad for the same duration. The calibrated SWAT model was used to predict the sediment, total nitrogen, and phosphorous influx in the Maithon reservoir. It has been observed that average sediment yield from different micro-watersheds varies from 0.231 to 7.458 ton/ha, while average monthly nitrogen and phosphorous yields vary from 0.224 to 1.377 kg/ha and 0.073 to 0.363 kg/ha, respectively, during the monsoon period. On the other hand, the net monthly average sediment yield and total nitrogen and phosphorous yields in the reservoir were found to be 1.53 M ton, 1834.2 kg, 191.1 kg, respectively. The results indicate there is a substantial influx of nutrients and sediments into the Maithon reservoir. The study not only provides insights on the potential NPS pollutant loading in the reservoir but also enables to identify the hotspot of NPS pollution where immediate mitigation measures have to be taken at priority basis.


Assuntos
Monitoramento Ambiental/métodos , Água Doce/análise , Sedimentos Geológicos/química , Modelos Teóricos , Poluição da Água/análise , Humanos , Hidrologia , Índia , Nitrogênio/análise , Fósforo/análise , Estações do Ano , Qualidade da Água
17.
Environ Pollut ; 253: 981-991, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31352190

RESUMO

Polycyclic aromatic hydrocarbons (PAHs) and aliphatic hydrocarbons (AHs), including petroleum biomarkers, were studied in four sediment cores collected around Deception and Penguin Islands, Antarctica. Total PAHs in Deception Island (DCP) samples ranged from 2.0 to 26.8 ng g-1, and in Penguin Island (PGI) varied between 13.2 and 60.3 ng g-1. Multiple sources of PAHs were verified in DCP, with petrogenic-derived compounds being predominant over the last 10 years. In PGI, PAHs related to natural contributions from the erosion of coal deposits were reported. Total AHs in DCP ranged from 4.5 to 19 µg g-1 and in PGI varied between 5.3 and 21.9 µg g-1. In DCP, the n-alkanes distribution pattern showed the presence of petroleum residues in the top sections and both terpanes and hopanes were detected, related to the use of fossil fuels for power generation and in different types of vessels. In PGI, the main source of n-alkanes was marine inputs and only terpanes were detected. The slight increase in hydrocarbon levels observed from 1980 onward in DCP was assumed to be due to the development of tourism in the region and to the scientific station activities. In PGI, anthropogenic-related hydrocarbons were detected in the recent sections and were linked to the development of tourism near the island, scientific activities and the increase in vessel traffic. In general, the concentrations of hydrocarbons found around both islands were comparable to those found in uncontaminated Antarctic regions.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Sedimentos Geológicos/química , Hidrocarbonetos/análise , Alcanos/análise , Regiões Antárticas , Decepção , Ilhas , Petróleo , Hidrocarbonetos Policíclicos Aromáticos/análise
18.
Environ Sci Pollut Res Int ; 26(23): 23219-23241, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31270770

RESUMO

As a kind of brominated flame retardants (BFRs), polybrominated diphenyl ethers (PBDEs) are extensively used in different types of electronic equipment, furniture, plastics, and textiles. PBDEs are ubiquitous environmental contaminants that may impact human health and ecosystems. Here we highlight recent findings on the occurrence, contamination status, and transport of PBDEs in soil, water/sediment, and air. Four aspects are discussed in detail: (1) sources of PBDEs to the environment; (2) occurrence and transport of PBDEs in soil; (3) PBDEs in aquatic ecosystems (water/sediment) and their water-sediment partitioning; and (4) the occurrence of PBDEs in the atmosphere and their gas-particle partitioning. Future prospects for the investigation on PBDEs occurrence are also discussed based on current scientific and practical needs.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Éteres Difenil Halogenados/análise , Poluentes do Solo/análise , Poluentes Químicos da Água/análise , Ecossistema , Retardadores de Chama/análise , Humanos
19.
Ecotoxicol Environ Saf ; 182: 109390, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31276884

RESUMO

Organochlorine pesticides have been banned for many years, but the residual trace amount of organochlorine in water may still pose ecotoxicological risk. Meanwhile, the potential risk of organochlorine pesticides released from sediments, especially into drinking water sources, is receiving increasing attention. The present study assessed the pollution and potential risk of drinking water sources along the midstream and downstream Yangtze River. Residues of organochlorine pesticides (OCPs) in water, suspended particle matter (SPM), and sediment were evaluated with isotope dilution HRGC/HRMS. The results indicated that OCPs in water, SPM, and sediment ranged in 0.52-92.97 ng/L, 0.10-4.10 ng/L, and 0.038-11.36 ng/g, respectively. The predominant OCPs in water, SPM, and sediment were ß-HCH, p,p'-DDE and PeCB. At site Y1, 8, 13, 18, ß-HCH has a higher proportion in sediment samples, while, α-HCH has a higher proportion in SPM samples. The industrial use of HCHs in the history was the main HCHs source for most water and sediment samples, which indicated an absence of fresh inputs of industrial HCHs. Meanwhile, the abundance of p,p'-DDE in water, sediment and SPM samples could be attributed to long-term aerobic degradation of DDTs. The values of ffsw of HCHs, DDTs and PeCB indicate the transfer from water to sediment. Risk assessment showed that HCHs and DDTs posed low ecotoxicological risk to the Yangtze River.


Assuntos
Diclorodifenil Dicloroetileno/análise , Água Potável/química , Monitoramento Ambiental/métodos , Hexaclorocicloexano/análise , Resíduos de Praguicidas/análise , Rios/química , China , Sedimentos Geológicos/química , Medição de Risco , Poluentes Químicos da Água/análise
20.
Environ Monit Assess ; 191(8): 499, 2019 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-31321548

RESUMO

In this study, we determined the levels of essential and non-essential elements in the Harris mud crab (Rhithropanopeus harrisii, Maitland, 1874) from the southern Baltic Sea. Results revealed high levels of Ca (246,000 ppm), Mg (11,000 ppm), Na (8160 ppm), K (3,780 ppm), and Fe (1830 ppm). The concentrations of essential metals such as Zn (62.5 ppm) and Cu (25 ppm) were similar to those recorded in other crab species. The concentrations of non-essential metals such as Pb (0.140 ppm), Cd (0.0017 ppm), and As (0.288 ppm) were well below the International Standards for Maximum Levels for Food. In view of the above, the Harris mud crab from the southern Baltic is safe to be used as a component of well-balanced feeds for terrestrial and aquatic animals.


Assuntos
Braquiúros/metabolismo , Monitoramento Ambiental/métodos , Espécies Introduzidas , Metais Pesados/análise , Oligoelementos/análise , Poluentes Químicos da Água/análise , Animais , Sedimentos Geológicos/química , Oceanos e Mares , Polônia , Água do Mar/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA