Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 32.618
Filtrar
1.
J Hazard Mater ; 416: 125818, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492783

RESUMO

Metal pollution poses a significant threat to ecological security and human health. Current research on the causes, sources and distribution of metal pollution in the Yangtze River plain is lacking. This study investigated the accumulation, risk, distribution, and sources of heavy metals in 62 lakes along the Yangtze River, and analyzed the relationship between river-lake connectivity, economic structure, population and metal diffusion. The mean concentrations of Cr, Cu, Hg, Zn, Cd, Pb and As in the surface sediments of these lakes were 90.8, 60.1, 0.06, 102, 0.89, 42.7, and 6.01 mg/kg, respectively. Most (99%) of the lake sediments were contaminated with Cd, and the lakes in the middle reach and southern bank of the Yangtze River had a higher ecological risk. Cr originated from the natural environment, whereas Zn, Cu, Pb, Cd and As were affected by human activities. The lakes disconnected from the Yangtze River had higher concentrations of Cu, Zn, Pb and As, while the lakes connected to the river had higher concentrations of Cd and Cr. This comprehensive analysis determined the pollution characteristics of heavy metals, illustrated the causes of non-point pollution in the Yangtze River plain, and showed that soil-water erosion is important in metal diffusion.


Assuntos
Metais Pesados , Poluentes Químicos da Água , China , Monitoramento Ambiental , Sedimentos Geológicos , Humanos , Lagos , Metais Pesados/análise , Metais Pesados/toxicidade , Medição de Risco , Rios , Poluentes Químicos da Água/análise
2.
Chemosphere ; 282: 131131, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34470169

RESUMO

This is an integrated assessment of the distribution of Cd, Cr, Hg and Pb in dissolved water, sediments and muscle fish tissues (Cynoscion guatucupa, Micropogonias furnieri, Mustelus schmitti and Ramnogaster arcuata) from the Bahía Blanca estuary, Argentina. Within the water fraction (µg L-1), Hg and Pb concentrations ranged from below the limit of detection (

Assuntos
Metais Pesados , Poluentes Químicos da Água , Animais , Monitoramento Ambiental , Peixes , Sedimentos Geológicos , Metais Pesados/análise , Água , Poluentes Químicos da Água/análise
3.
Environ Monit Assess ; 193(10): 633, 2021 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-34490544

RESUMO

Diagnostic ratios and compound-specific isotopic analysis (CSIA) are two tools that can help identify and differentiate the petrogenic and biogenic sources of hydrocarbons found in environmental samples. The present study aims to evaluate the concentration and type of n-alkanes and isoprenoids found in the oligotrophic waters of the Gulf of Mexico (n = 14), and through the typical diagnostic ratios reported for n-alkanes and its carbon isotopic composition (δ13C) to establish and differentiate the possible source of the hydrocarbons. Additionally, crude oil samples (n = 10) extracted in the Gulf of Mexico were evaluated by CSIA as a possible source of hydrocarbons to the study area. We found that the CSIA of δ13C for n-alkanes (n-C11 to n-C30) and isoprenoids (pristane and phytane) found in the surface water samples varied from - 25.55 to - 37.59‰ and from - 23.78 to - 33.97‰ in the crude oil samples, values which are more related to petrogenic sources. An analysis of the δ13C for pristane vs. phytane suggests that only three surface water samples show an origin in common that those observed in crude oils of the Gulf of Mexico. A low incidence of odd- and even-numbered n-alkanes higher than n-C25 in the water samples indicate low to negligible presence of terrigenous sources into the area, which was supported by the carbon isotopic composition of the individual n-alkanes.


Assuntos
Petróleo , Poluentes Químicos da Água , Alcanos/análise , Isótopos de Carbono/análise , Monitoramento Ambiental , Sedimentos Geológicos , Golfo do México , Petróleo/análise , Terpenos , Poluentes Químicos da Água/análise
4.
Sci Total Environ ; 792: 148215, 2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34465034

RESUMO

Tidal flats are biogeomorphic landscapes, shaped by physical forces and interaction with benthic biota. We used a metabolic approach to assess the overarching effect of bioturbators on tidal landscapes. The benthic bivalve common cockle (Cerastoderma edule) was used as model organism. The effect of C. edule on sediment resuspension was approximated as a function of the overall population metabolic rate per unit of area. We combined i) laboratory observations on how C. edule affect sediment resuspension along gradients of bioturbation activity, sediment cohesiveness and hydrodynamic force with ii) spatial data on the natural distribution of intertidal C. edule populations. This allowed us to build an integrated model of the C. edule effect on sediment resuspension along the tidal gradient. Owing to the temperature dependence of metabolic rate, the model also accounted for seasonal variation in bioturbators activity. Laboratory experiments indicated that sediment resuspension is positively related to the metabolic rate of the C. edule population especially in cohesive sediments. Based on this observation, we predicted a clear spatial and seasonal pattern in the relative importance of C. edule contribution to sediment resuspension along a tidal transect. At lower elevations, our model indicates that hydrodynamics overrules biotic effects; at higher elevations, inter-tidal hydrodynamics should be too low to suspend bioturbated sediments. The influence of C. edule on sediment resuspension is expected to be maximal at the intermediate elevation of a mudflat, owing to the combination of moderate hydrodynamic stress and high bioturbator activity. Also, bio-mediated sediment resuspension is predicted to be particularly high in the warm season. Research into metabolic dependency of bio-mediated sediment resuspension may help to place phenomenological observations in the broader framework of metabolic theories in ecology and to formulate general expectations on the coastal ecosystem functioning.


Assuntos
Bivalves , Cardiidae , Animais , Ecossistema , Sedimentos Geológicos , Hidrodinâmica
5.
Sci Total Environ ; 792: 148454, 2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34465049

RESUMO

Nano zero-valent iron particles (nZVI, 0.09 wt%), micro zero-valent iron particles (mZVI, 0.09 wt%), granular activated carbon (GAC, 3.03 wt%), GAC supported nZVI (nZVI/GAC, 3.12 wt%) and nZVI&GAC (nZVI 0.09 wt%, GAC 3.03 wt%) were evaluated for their effects on polychlorinated biphenyls (PCBs) anaerobic reductive dechlorination, detoxification, as well as microbial community structure in Taihu Lake (China) sediment microcosms. The results showed that all of these five materials could stimulate PCBs reductive dechlorination, especially for dioxin-like PCB congeners, and nZVI&GAC had the best removal effect on PCBs. The reduction of total PCBs increased from 13.5% to 33.2%. H2 generated by zero-valent iron corrosion was utilized by organohalide-respiring bacteria (OHRB) to enhance the dechlorination of PCBs predominantly via meta chlorine removal in the short term. The addition of ZVI had little impact on the total bacterial abundance and the microbial community structure. The adsorption of GAC and potential bioremediation properties of attached biofilm could promote the long-term removal of PCBs. GAC, nZVI/GAC, nZVI&GAC had different influences on the microbial structure. These findings provide insights into the biostimulation technique for in situ remediations of PCBs contaminated sediments.


Assuntos
Microbiota , Bifenilos Policlorados , Biodegradação Ambiental , Catálise , Cloro , Sedimentos Geológicos , Ferro , Lagos , Bifenilos Policlorados/análise
6.
Sci Total Environ ; 792: 148416, 2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34465054

RESUMO

Excess diffuse fine sediment losses from agriculture are associated with a reduction in the ecological status of lakes and rivers. Agri-environment initiatives aim to help reduce these excessive losses through targeted on-farm advice and capital grants. However, to deliver optimum cost-benefit such initiatives must target the most important sediment sources. Sediment source fingerprinting provides an approach by which sediment provenance data can be generated; however, conventional tracers are expensive and state-of-the-art data processing for source discrimination and apportionment requires significant expertise. In consequence, sediment fingerprinting is not routinely used for catchment management. Against this context, sediment colour measured using an ordinary document scanner is trialled as an inexpensive and accessible tracer in eight catchments classed as high priority for an agri-environment initiative in England. Colour is interpreted using simple scatter bi-plots of source and sediment samples and compared to the results produced by a conventional composite tracer sediment source fingerprinting methodology. It was found that in two study catchments, sediment colour was as effective as conventional sediment fingerprinting. In four catchments, sediment colour provided less source discrimination or minor differences in results but still identified the most important targets for sediment mitigation. In two catchments, colour was un-successful; however, significant challenges were also encountered with more conventional tracers due to specific local conditions. The findings suggest that use of low-cost colour tracers by non-experts has the potential to significantly increase the uptake of sediment source tracing to improve the cost-benefit of agri-environment initiatives combating the degradation of water quality and aquatic ecology by accelerated sediment losses.


Assuntos
Sedimentos Geológicos , Rios , Agricultura , Cor , Inglaterra
7.
J Hazard Mater ; 416: 126141, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492930

RESUMO

Microbial communities in hyporheic zones (HZ) provide vital biogeochemical functions such as contaminant degradation for river ecosystems. Antibiotics are contaminants that have been increasingly detected in HZ sediments. In this study, sediments from different HZ locations in a contaminated river, Maozhou river, China were sampled and analyzed using qPCR and high-throughput sequencing to investigate the effect of antibiotic contamination on microbial community structures and functions in HZ sediments. Results indicated that types and concentrations of antibiotics in HZ sediments were heterogeneously distributed that were largely consistent with the distribution of antibiotic sources. Sediments near animal farm and hospital contained higher antibiotic concentrations compared with those from mainstream. The distribution of ARGs was well correlated with antibiotics. Bacterial indicator genera indicating differences between mainstream area and other sampling areas were positively correlated with antibiotics, suggesting the influences of antibiotics on reshaping microbial community structures. PICRUSt revealed positive relationships between antibiotics and predicted functional genes involved in defense, signal transduction, and recombination and repair. This imply the defensive response of microbial communities on antibiotic attack. These results indicated that antibiotic contamination in the watershed posed a potential risk on HZ microbial community structures and functions, which may further threaten river ecosystem functions.


Assuntos
Sedimentos Geológicos , Microbiota , Antibacterianos , Bactérias/genética , China , Genes Bacterianos , Rios
8.
J Hazard Mater ; 416: 126163, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492941

RESUMO

Environmental magnetism in combination with machine learning can be used to monitor heavy metal pollution in sediments. Magnetic parameters and heavy metal concentrations of sediments from Chaohu Lake (China) were analyzed. The magnetic measurements, high- and low-temperature curves, and hysteresis loops showed the primary magnetic minerals were ferrimagnetic minerals in sediments. For most metals, their concentrations were highest during the wet season and lowest during the medium-water period. Cd, Hg, and Zn were moderately enriched and Cd and Hg posed a considerable ecological risk. A redundancy analysis indicated a relationship between physicochemical indexes and magnetic parameters and heavy metal concentrations. An artificial neural network (ANN) and support vector machine (SVM) were used to construct six models to predict the heavy metal concentrations and ecological risk index. The inclusion of both the physicochemical indexes and magnetic parameters as input factors in the models were significantly ameliorated the simulation accuracy for the majority of heavy metals. The training and test R, for Be, Fe, Pb, Zn, As, Cu, and Cr were > 0.8. The SVM showed better performance and hence it has potential for the efficient and economical long-term tracking and monitoring of heavy metal pollution in lake sediments.


Assuntos
Metais Pesados , Poluentes Químicos da Água , China , Monitoramento Ambiental , Sedimentos Geológicos , Lagos , Aprendizado de Máquina , Metais Pesados/análise , Medição de Risco , Poluentes Químicos da Água/análise
9.
J Hazard Mater ; 416: 126170, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492946

RESUMO

Dissolved arsenic typically results from chemical weathering of arsenic rich sediments and is most often found in oxidized forms in surface water. The mobility of arsenic is controlled by its valence state and also by its association with iron oxides minerals, the forms of which are both influenced by abiotic and biotic processes in aqueous environment. In this study, speciation methods were used to measure and confirm the presence of reduced arsenic species in the surface water of Frenchman creek, a gaining stream that crosses the Colorado-Nebraska border. Selective extraction analysis of aquifer and stream bed sediments shows that the bulk of the arsenic occurs with labile iron-rich oxy(hydroxide) minerals. Total dissolved arsenic in surface and groundwater ranged from ~3-18 µg L-1, and reduced arsenic species comprise about 41% of the total dissolved arsenic (16.0 µg L-1) in Frenchman creek. Leachable arsenic in the aquifer sediment samples ranged up to 1553 µg kg-1, while samples from Frenchman creek bed sediments contained 4218 µg kg-1. Dynamic surface and groundwater interaction sustains arsenite in iron-rich surface headwaters, and the implied toxicity of reduced arsenic in this hydrogeological setting, which can be important in surface water environments around the globe.


Assuntos
Arsênio , Arsenitos , Água Subterrânea , Poluentes Químicos da Água , Arsênio/análise , Monitoramento Ambiental , Sedimentos Geológicos , Nebraska , Rios , Poluentes Químicos da Água/análise
10.
J Hazard Mater ; 416: 126204, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492967

RESUMO

We assessed the contributions of Cu smelting and Asian dust influx to metal(loid) pollution over the last century based on metal(loid) concentrations, Pb isotope ratios, and 210Pb dating of sediments from Gunsan Reservoir, South Korea. During the pre-industrial period (1827-1936), heavy metal pollutants were predominantly geogenic. Local smelting activity was dominant between 1936 and 2008. Between 1936 and 1971, Cu and Pb contamination was not significant, with contributions from smelting activities accounting for < 6.2% of the measured concentrations. In contrast, anthropogenic Cu and Pb inputs increased between 1971 and 2008 due to intense smelting activity. Based on the similar 206Pb/207Pb ratios of the reservoir sediments and smelter bottom ash, anthropogenic contributions reached 95% during 1987-1995. In comparison, the sediments deposited between 2008 and 2018 were characterized by a higher Zn and Cd geoaccumulation index and enrichment factor values and less-radiogenic Pb signals than the regional geogenic Pb signal. These trends are attributed to the long-range transport of pollutants from China, the contribution of which gradually increased from 11.0% in 2008 to 19.2% in 2018. Our results show that reservoir sediments are valuable archives for reconstructing metal(loid) contamination histories and changes in pollution sources over time.


Assuntos
Metais Pesados , Poluentes Químicos da Água , China , Poeira/análise , Monitoramento Ambiental , Sedimentos Geológicos , Isótopos , Metais Pesados/análise , República da Coreia , Medição de Risco , Poluentes Químicos da Água/análise
11.
J Hazard Mater ; 416: 126240, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492991

RESUMO

Mineral dissolution and secondary phase precipitation may control the fate of inorganic contaminants introduced to soils and sediments during liquid waste discharges. When the solutions are aggressive enough to induce transformation of native minerals, incorporated contaminants may be released during dissolution due to percolation of meteoric waters. This study evaluated the release of uranium (U) from Hanford sediments that had been previously reacted for 180 or 365 days with liquid waste solutions containing U with and without 3 mM dissolved phosphate at pH 2 and 3. Flow-through column experiments were conducted under continuous saturated flow with a simulated background porewater (BPW; pH ~7) for 22 d. Up to 5% of the total U was released from the sediments reacted under PO4-free conditions, attributable to the dissolution of becquerelite and boltwoodite formed during weathering. Contrastingly, negligible U was released from PO4-reacted sediments, where meta-ankoleite was identified as the main U-mineral phase. Linear combination fits of U LIII-edge EXAFS spectra of sediments before and after BPW leaching and thermodynamic calculations suggest that the formed becquerelite and meta-ankoleite transformed into schoepite and a phosphuranylite-type phase, respectively. These results demonstrate the stabilization of U as recalcitrant uranyl minerals formed in sediments and highlight the key role of PO4 in U release at contaminated sites.


Assuntos
Urânio , Poluentes Radioativos da Água , Sedimentos Geológicos , Minerais , Fosfatos , Urânio/análise , Poluentes Radioativos da Água/análise
12.
Water Sci Technol ; 84(5): 1257-1269, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34534121

RESUMO

Long-term polluted rivers often lead to the accumulation of heavy metals in sediments. Anthropogenic activities or biological disturbances break the adsorption balance, causing them to return from the bottom mud to the overlying water and change the aquatic environment. In order to understand the variation of heavy metals between sediments and river water, we collected the riverbed sediments in the polluted Xinhe River and carried out static continuous infiltration and dynamic uninterrupted disturbance experiments. The leaching experiment shows that the absorbability of Cd and Pb is stronger than Cr in the sediment; at the same time, the properties of the medium have a great influence on the adsorption of heavy metals. The disturbance can prompt heavy metals in the sediment to resuspend into the overlying water. The impact is the greatest during the first 12 h, and the influence degree is stronger in the relatively static water than in the moving river. In addition, pH and other factors have different degrees of influence on the desorption of heavy metals.


Assuntos
Metais Pesados , Poluentes Químicos da Água , Adsorção , China , Monitoramento Ambiental , Sedimentos Geológicos , Metais Pesados/análise , Medição de Risco , Rios , Água , Poluentes Químicos da Água/análise
13.
J Hazard Mater ; 416: 125909, 2021 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492843

RESUMO

Twenty-two water samples from the Thirumanimuthar River course in southern India were collected before COVID-19 lockdown and during COVID-19 lockdown periods and were analyzed for microbiological parameters (fecal coliform bacteria, total coliform bacteria, Escherichia coli, and fecal streptococci) and heavy metals (Fe, Mn, Zn, Cu, Cd, Ni, Pb and Cr). The lockdown has decreased microbial populations and heavy metals. Fe, Cu, Cd, Ni, Pb and Cr exceeded the drinking water limits, respectively, in 77%, 45%, 27%, 18%, 9% and 91% of the pre-lockdown samples. During the lockdown period, Fe, Cu and Cd concentrations in 23% and Cr in 50% of the samples exceeded the limits. Heavy Metal Pollution Index (PI) expressed that 27%, 64% and 9% of the pre-lockdown samples represented 'low', 'medium' and 'high' pollution categories, respectively, but 68% and 32% of the lockdown period samples represented 'low' and 'medium' categories, respectively. The Metal Index (MI) exposed that all samples of pre-lockdown were under the seriously affected category, whereas 54% and 46% of lockdown samples were under strongly and seriously affected categories, respectively. Health risk evaluation predicted that 95%, 91% and 86% of pre-lockdown samples and 45%, 36% and 33% of lockdown period samples were at risk among children, teenagers and adults, respectively. As there is no integrated study on river water quality of COVID-19 lockdown this work is uniquely carried out by combining heavy metal pollution, microbial contamination and human health risk evaluation.


Assuntos
COVID-19 , Metais Pesados , Poluentes Químicos da Água , Adolescente , Adulto , Criança , China , Controle de Doenças Transmissíveis , Monitoramento Ambiental , Sedimentos Geológicos , Humanos , Índia , Metais Pesados/análise , Metais Pesados/toxicidade , Pandemias , Medição de Risco , Rios , SARS-CoV-2 , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
14.
Appl Microbiol Biotechnol ; 105(14-15): 6103-6115, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34338804

RESUMO

Metoprolol is widely used as a beta-blocker and considered an emerging contaminant of environmental concern due to pseudo persistence in wastewater effluents that poses a potential ecotoxicological threat to aquatic ecosystems. Microbial removal of metoprolol in the redox-delineated hyporheic zone (HZ) was investigated using streambed sediments supplemented with 15 or 150 µM metoprolol in a laboratory microcosm incubation under oxic and anoxic conditions. Metoprolol disappeared from the aqueous phase under oxic and anoxic conditions within 65 and 72 days, respectively. Metoprolol was refed twice after initial depletion resulting in accelerated disappearance under both conditions. Metoprolol disappearance was marginal in sterile control microcosms with autoclaved sediment. Metoprolol was transformed mainly to metoprolol acid in oxic microcosms, while metoprolol acid and α-hydroxymetoprolol were formed in anoxic microcosms. Transformation products were transient and disappeared within 30 days under both conditions. Effects of metoprolol on the HZ bacterial community were evaluated using DNA- and RNA-based time-resolved amplicon Illumina MiSeq sequencing targeting the 16S rRNA gene and 16S rRNA, respectively, and were prominent on 16S rRNA rather than 16S rRNA gene level suggesting moderate metoprolol-induced activity-level changes. A positive impact of metoprolol on Sphingomonadaceae and Enterobacteriaceae under oxic and anoxic conditions, respectively, was observed. Nitrifiers were impaired by metoprolol under oxic and anoxic conditions. Collectively, our findings revealed high metoprolol biodegradation potentials in the hyporheic zone under contrasting redox conditions associated with changes in the active microbial communities, thus contributing to the attenuation of micropollutants. KEY POINTS: • High biotic oxic and anoxic metoprolol degradation potentials in the hyporheic zone. • Key metoprolol-associated taxa included Sphingomonadaceae, Enterobacteraceae, and Promicromonosporaceae. • Negative impact of metoprolol on nitrifiers.


Assuntos
Metoprolol , Microbiota , Bactérias/genética , Biodegradação Ambiental , Sedimentos Geológicos , RNA Ribossômico 16S/genética
15.
Molecules ; 26(16)2021 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-34443439

RESUMO

Ten polyketide derivatives (1-10), including a new natural product named (E)-2,4-dihydroxy-3-methyl-6-(2-oxopent-3-en-1-yl) benzaldehyde (1), and five known diketopiperazines (11-15), were isolated from the mangrove-sediment-derived fungus Aspergillus sp. SCSIO41407. The structures of 1-15 were determined via NMR and MS spectroscopic analysis. In a variety of bioactivity screening, 3 showed weak cytotoxicity against the A549 cell line, and 2 exhibited weak antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). Compounds 3, 5, and 6 showed inhibition against acetylcholinesterase (AChE) with IC50 values of 23.9, 39.9, and 18.6 µM. Compounds 11, 12, and 14 exhibited obvious inhibitory activities of lipopolysaccharide (LPS)-induced nuclear factor-κB (NF-κB) with IC50 values of 19.2, 20.9, and 8.7 µM, and they also suppressed RANKL-induced osteoclast differentiation in bone marrow macrophages cells (BMMCs), with the concentration of 5 µM. In silico molecular docking with AChE and NF-κB p65 protein were also performed to understand the inhibitory activities, and 1, 11-14 showed obvious protein/ligand-binding effects to the NF-κB p65 protein.


Assuntos
Aspergillus/efeitos dos fármacos , Dicetopiperazinas/farmacologia , Sedimentos Geológicos/microbiologia , Policetídeos/farmacologia , Rhizophoraceae/química , Células A549 , Acetilcolinesterase/metabolismo , Morte Celular/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Inibidores da Colinesterase/farmacologia , Dicetopiperazinas/química , Humanos , Lipopolissacarídeos/farmacologia , Testes de Sensibilidade Microbiana , Simulação de Acoplamento Molecular , NF-kappa B/metabolismo , Osteoclastos/citologia , Osteoclastos/efeitos dos fármacos , Policetídeos/química , Espectroscopia de Prótons por Ressonância Magnética , Ligante RANK/farmacologia
16.
Biomed Res Int ; 2021: 6635903, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34337039

RESUMO

Total concentrations of As, Cd, Cr, Cu, Pb, and Zn in sediment samples obtained from Wami Estuary in Tanzania were used to generate contaminant probability density distributions and species sensitivity distributions using the AQUARISK model. Results of tier 1 assessment showed that As, Cd, Cr, Pb, and Zn were not of concern as their measured values and the 99th percentile of the fitted distributions were lower than the SQG low-trigger values. However, Cu was identified as of concern in this estuary. According to the Bur III distributional analysis of the exotoxicological data, the estimated percentage of species likely to be affected is 3.4, 79.4, 79.8, 99.9, 98.4, and 98.0 for As, Cd, Cr, Cu, Pb, and Zn, respectively. Lowering of the current median concentrations of metals (Cd, Cr, Cu, Pb, and Zn) is recommended as they exceeded modeled median target sediment concentration to achieve 95% or higher for species protection. With the ongoing increase in anthropogenic activities in the Wami River catchment, the environmental regulatory bodies may use the findings of the present study and augmented with AQUARISK to set discharge standards for various contaminants in order to minimize impacts to the receiving ecosystems.


Assuntos
Ecossistema , Estuários , Sedimentos Geológicos/química , Metais Pesados/análise , Modelos Estatísticos , Medição de Risco , Geografia , Tanzânia
17.
Environ Monit Assess ; 193(9): 579, 2021 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-34398331

RESUMO

The concentrations of 28 polychlorinated biphenyls (PCBs) were determined in soils collected at three depths from thirteen different sites along the floodplain of the lower reaches of the River Niger (LRRN) in Nigeria. The aim of the study was to provide data on the levels of contamination, sources of the contaminants, and risks to the ecosystem and humans. Soil samples were Soxhlet extracted with a solvent mixture of dichloromethane (DCM)/n-hexane and cleaned up on a column packed with Florisil and silica gel. The PCBs in the samples were quantified by gas chromatography-mass spectrometry. The Æ©28 PCB concentrations in the floodplain soils varied between not detected (nd) and 11,151 ng g-1 for different sampling sites and depths. The PCB concentrations and homologue distribution patterns in soil profiles of the floodplain of the LRRN showed remarkable differences with respect to sites and depths. The results obtained were used to evaluate the ecological and human health risks, which indicated that there is a potential risk to organisms and humans from exposure to PCBs in these soil profiles. The source evaluation as determined by principal component analysis suggested that PCBs in these soil profiles came from burnt circuit boards, cable wires, use of paints, discharges from transformers, long-range migration, and deposition.


Assuntos
Bifenilos Policlorados , Poluentes do Solo , Poluentes Químicos da Água , Ecossistema , Monitoramento Ambiental , Sedimentos Geológicos , Humanos , Níger , Nigéria , Bifenilos Policlorados/análise , Rios , Solo , Poluentes do Solo/análise , Poluentes Químicos da Água/análise
18.
Environ Pollut ; 286: 117578, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34438499

RESUMO

Heavy metal pollution in lake systems has arisen plenty of threats for public health because of its high toxicity, persistence, and bioaccumulation. Whereas heavy metals are inextricably linked with bioavailability in pore water and overlying water. Lake Jiaogang is classified as an important water-carrying lake situated in the northern part of the Anhui Province China. In recent years, water quality in this lake declined due to increasing fishery aquaculture, livestock, and tourism. This study aims to bring insight into the interactions of heavy metal elements across sediment-water interface in Lake Jiaogang. Four representative regions were selected, more than ten heavy metals were chosen to quantify by the Community Bureau of Reference, diffusive gradient in thin-film (DGT), and high-resolution pore water equilibrators. The results showed that most heavy metals corresponded with the reducible fraction, acid-soluble fraction, and oxidizable fraction in the Eastern area (sample 3#) and aquaculture area (sample 4#) were higher than that of emergent plant area (sample 1#), and floating plant area (sample 2#). The average fluxes of heavy metals (except Ni and Zn in sample 3#, F value > 0 pg/cm2/d) in the four sampling sites were observed in the lower reaches (F value < 0 pg/cm2/d). The vertical distribution of heavy metals was extracted by DGT, such as As (exclude 2#), Co, Fe, Mn, and Zn (contain 4#) showed an increased content with increasing depth in the four sampling sites. In the pore and overlying water, concentrations of heavy metals from the sample 3# and 4# were higher than those of sample 1# and 2#. Heavy metal pollution in anthropogenic activity areas was higher than those in areas with ecological vegetation, and risk control in this area should be strengthened.


Assuntos
Metais Pesados , Poluentes Químicos da Água , China , Monitoramento Ambiental , Sedimentos Geológicos , Lagos , Metais Pesados/análise , Medição de Risco , Água , Poluentes Químicos da Água/análise , Qualidade da Água
19.
Environ Monit Assess ; 193(9): 589, 2021 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-34415414

RESUMO

To explore the pollution status of heavy metals and potential risks in the Yongding New River of Tianjin, China, a comparative study of concentrations of heavy metals (Cd, Cr, Cu, Pb, Zn, As, and Hg) in surface sediments from submerged areas (SA), fluctuant flooded district (FFD), and non-flooded district (NFD) was conducted. In the present study, a modified three-stage European Community Bureau of Reference sequential extraction procedure and EDTA-Na2 single extraction were used to determine the heavy metal distribution in different sediment samples. Results showed that Cd was the metal with the highest contamination level compared to a background value of Tianjin soils, particularly in SA, followed by As. The concentrations of Cr, Pb, Cu, and Zn were relatively higher in upstream. Cu and Pb had higher bioavailability when compared with the other metals, indicating the two metals were easier to be mobilized. The Pearson correlation coefficient is applied to assess the degree of correlation between heavy metals. As, Cu, Zn, and Hg had the strong correlation, implying they may have common sources. Human activity in the riparian such as agricultural production, vehicle, and burning coal increased inputs of heavy metals in the surface sediments and influenced their distribution spatially. Besides, we also calculated geo-accumulation indexes (Igeo) and eco-risk index to assess the degree of risk of heavy metals in sediments. The Igeo were higher in SA than in FFD and NFD. Based on Igeo and potential eco-risk index, Cd has the highest risk, followed by As and Hg.


Assuntos
Metais Pesados , Poluentes Químicos da Água , Monitoramento Ambiental , Sedimentos Geológicos , Humanos , Metais Pesados/análise , Medição de Risco , Rios , Água , Poluentes Químicos da Água/análise
20.
Huan Jing Ke Xue ; 42(9): 4275-4286, 2021 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-34414725

RESUMO

In this study, total phosphorus (TP) and the phosphorus (P) fractions in the water and surface sediments of the Baotou Nanhai wetland in China were determined using molybdenum blue/ascorbic acid spectrophotometry and continuous extraction methods. An APCS-MLR receptor model was combined with correlation analysis (CA) and principal component analysis (PCA) to identify and quantify the pollution sources. The results showed ① differences in the pollution level of phosphorus between the surface sediments and water. The contribution of dissolved inorganic phosphorus (DIP) to TP in the water (WTP) was the lowest, while the contribution of calcium-bound phosphorus (HCl-P) to TP in the surface sediments (STP) was the largest in the study area. The surface sediments of the Nanhai Lake (L area) and the wetland plant area (P area) exhibited high bioavailability and the potential for releasing phosphorus into the water, which could result in eutrophication and is therefore of concern. ② The APCS-MLR receptor model indicated that the main pollution sources of phosphorus were industrial wastewater and domestic sewage (29.07%), and pesticides and fertilizers (29.00%). In addition, the degradation of animal and plant residues (18.49%) also contributed to pollution in the study area.


Assuntos
Fósforo , Poluentes Químicos da Água , Monitoramento Ambiental , Sedimentos Geológicos , Fósforo/análise , Águas Residuárias , Poluentes Químicos da Água/análise , Áreas Alagadas
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...