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1.
Environ Monit Assess ; 193(10): 634, 2021 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-34491451

RESUMO

We studied the water quality of the riparian firefly sanctuary of Sungai Rembau, or Rembau River, in Negeri Sembilan, Malaysia, from January 2018 to November 2018 to determine the possible influence of the physico-chemical characteristics of the water on the firefly populations living within the sanctuary. We set up a total of five water quality sampling stations and 10 firefly sampling stations along the river. Dissolved oxygen (DO), temperature, pH and electrical conductivity (EC) were measured in situ, while chemical oxygen demand (COD), total suspended solids (TSS), biochemical oxygen demand (BOD) and ammonia-nitrogen (NH3-N) were analysed in the laboratory. Firefly samples were collected using a sweep net at both day and night for 1 min. Sungai Rembau was categorized as Class II on the Malaysian water quality index (WQI), which indicates slight pollution. Except for EC and DO, the water quality parameter values were not significantly different (p > 0.05) between the sampling stations. A total of 529 firefly individuals consisting of Pteroptyx tener (n = 525, 99.24%), P. malaccae (n = 3, 0.57%) and P. asymmetria (n = 1, 0.19%) were collected. There was significant correlation between firefly abundance and BOD (r = - 0.198, p < 0.05), NH3-N (r = - 0.150, p < 0.05) and pH (r = 0.408, p < 0.05). The results show that the firefly populations in Sungai Rembau are sensitive to organic compounds, which may be present in the form of pollutants from anthropogenic activities near their natural habitat.


Assuntos
Rios , Poluentes Químicos da Água , Animais , Monitoramento Ambiental , Vaga-Lumes , Humanos , Malásia , Poluentes Químicos da Água/análise , Qualidade da Água
2.
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
3.
Water Res ; 203: 117488, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34482236

RESUMO

The biodegradability of the anticonvulsant pregabalin (PGB) was studied in laboratory incubation experiments in contact with water/sediment systems under different redox conditions. PGB was degraded by biological processes under aerobic conditions reaching half-lives of 8 to 10 d, while inactivated and anaerobic control experiments revealed no significant decrease of PGB concentrations. Within experiments spiked with elevated PGB concentrations, 12 TPs were formed and tentative chemical structures could be proposed by accurate masses and fragmentation pathways detected via measurements with high resolution mass spectrometry (LC-QToF-MS). Four of the proposed TPs were finally confirmed either by authentic reference standards (PGB-Lactam, ISA, TP 157-A (II)) or a self-synthesized standard (NA-PGB). PGB-Lactam was identified as the quantitatively most relevant TP formed via intramolecular cyclization under aerobic conditions, reaching up to 33% of the initial PGB concentration. Incubation experiments spiked with PGB-Lactam revealed three times higher half-lives compared to the parent compound, indicating that PGB-Lactam is more stable than PGB. A comparison with results gained from water/sediment incubation experiments with the structurally related compound gabapentin (GBP) revealed, that the transformation behaviour can be mainly extrapolated to PGB. Most of the observed transformation reactions found for PGB were comparable to the ones found for GBP. The TPs PGB-Lactam and NA-PGB as well as three GBP TPs (GBP-Lactam, NA-GBP and CCHA) have been detected in German wastewater treatment plants (WWTPs) effluents and the river Rhine including some of its tributaries such as Main, Neckar, Moselle and Aare. Moreover, GBP and PGB as well as some of their TPs were detected in German bank filtrates and finished drinking waters up to 260 ng L-1. For that reason these compounds should be monitored in drinking water in the future.


Assuntos
Poluentes Químicos da Água , Água , Biotransformação , Gabapentina , Pregabalina , Rios , Águas Residuárias , Poluentes Químicos da Água/análise
4.
Environ Monit Assess ; 193(10): 640, 2021 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-34505939

RESUMO

As of mid-2021, four hydroelectric dams are operational on the main channel of the Teesta River in the mountainous and tectonically active Sikkim-Darjeeling-Kalimpong region of India. Riparian ecological and fluvial morphological changes after damming have not been documented. This paper describes an early study of a section of the middle Teesta River, at two of the dam-created reservoirs, just before the river enters the plains. High-resolution, multi-beam, geo-located sonar was used to map the bathymetry of the reservoirs. This resulted in the creation of 30cm-resolution bathymetric maps of the two reservoirs showing valley bottom morphology within them. The bathymetric maps were compared with pre-dam digital elevation models of the valley to create topographic change-maps. The change-maps indicate significant differences in valley morphology due to erosion and deposition processes. Land cover changes due to inundation were quantified from analysis of satellite imagery time series data of the reservoir riparian zones. Land cover change analysis showed a loss of ~ 74,000 trees in ~ 225 ha of flooded riparian corridors due to long-term inundation. The study shows that the dams have caused 7.4% of the river length to become quasi-lentic, and drastically altered sediment dynamics and hydrologic flow. Sediment deposition calculations indicate the reservoirs losing almost three-quarters of their surface areas to sediment deposition features within 15 years. This study will serve as an important baseline for future studies, and influence design and policy regarding riparian and fluvial ecosystem management, monitoring, and evaluation in the Teesta and similar mountainous river basins in the Eastern Himalaya.


Assuntos
Ecossistema , Rios , Monitoramento Ambiental , Inundações , Árvores
5.
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
6.
Environ Monit Assess ; 193(9): 614, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34468858

RESUMO

Habitat quality is an important indicator for measuring regional biodiversity and ecosystem service value. A change in habitat quality is the direct result of the interaction between human activities and the natural environment. In this study, the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model was used to evaluate the habitat quality of the Yellow River Basin (YRB) from 1980 to 2018. We further analyzed the quantity and spatial transfer status of habitat quality quantitatively using the Geo-informatic Tupu method. The results show that the habitat degradation degree under human disturbance showed a trend of increasing first and then decreasing, with values of 0.0196 in 1980, 0.0200 in 2000, and 0.0199 in 2018. In addition, it presents two ring structures: light-severe-high-moderate and light-moderate-high-severe in space. The overall level of habitat quality in the basin is relatively good, but there is a trend of decline, which are 0.6091, 0.6069, and 0.6049 in the three stages respectively. The spatial distribution of habitat quality showed a pattern of high in the middle and low on both sides. The habitat quality has been restored in some areas. The transition between good and medium and good and excellent in the Tupu change units of the habitat quality grade is the most intense. Both stages are mainly the transformation from high-grade to low-grade habitat quality, but there is a trend of gradual improvement. The findings could have theoretical support and policy implications for the maintenance of biodiversity and the protection of the natural environment in the Yellow River Basin.


Assuntos
Ecossistema , Rios , China , Conservação dos Recursos Naturais , Monitoramento Ambiental , Humanos
7.
Biol Lett ; 17(9): 20210346, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34493065

RESUMO

The European eel's singular spawning migration from European waters towards the Sargasso Sea remains elusive, including the early phase of migration at sea. During spawning migration, the movement of freshwater resident eels from river to sea has been thought to be irreversible. We report the first recorded incidents of eels returning to the river of origin after spending up to a year in the marine environment. After migrating to the Baltic Sea, 21% of the silver eels, tagged with acoustic transmitters, returned to the Narva River. Half returned 11-12 months after moving to the sea, with 15 km being the longest upstream movement. The returned eels spent up to 33 days in the river and migrated to the sea again. The fastest specimen migrated to the outlet of the Baltic Sea in 68 days after the second start-roughly 1300 km. The surprising occurrence of returning migrants has implications for sustainable management and protection of this critically endangered species.


Assuntos
Anguilla , Rios , Acústica , Migração Animal , Animais
8.
J Environ Manage ; 298: 113423, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34526286

RESUMO

The Yellow River, with a developmental and historical significance to China, is now facing several emerging pressures, which are degrading the river status and creating challenges for high-quality development in the basin. Numerous studies on such emerging pressures, present scattered outcomes, and trigger uncertainties and deficient assumptions on the river's problems. This review integrated such scattered information and investigated the emerging pressures, their drivers and integrated impacts at the basin level. The study intended to prioritize those pressures needing expeditious consideration, and carried a discussion on the alternative pathways to the solution. To determine the critical emerging pressures, a literature review was conducted and experts' opinion was sought. The outcome further led to a comprehensive review, data collection, and analysis of three groups of emerging pressures. The review recognized 'Water Stress' in the lower reach, primarily caused by an abated flow, as the most distressing emerging pressure inflicting social, ecological, and economic consequences. Such decline in flow was mostly induced by a recent increase in 'Anthropogenic activities', such as intensive water withdrawal for irrigation (≥27 BCM), and construction of check dams in the Loess Plateau region (trapping~5 BCM water). The increasing 'Pollution' in the river, besides threatening public health and ecology, also contributed to the water stress by rendering certain stretches of the river biologically dead and unsuitable for any use. The 'Climate Change', with its key negative effect on precipitation in the middle sub-basin, overall contributed small (8-11 %) to the observed reduction in river flow. With increasing challenges for the adopted engineering solutions tackling the water stress, the study suggested the use of a demand management approach, employing adaptive policy measures, as an alternative or supplementary solution to the current approach. In addition, the study highlights that regular reviewing and reforming the key decisions based on evidence and updated information, and taking a participatory approach, may offer a sustainable pathway to the environment as well as socio-economic goals.


Assuntos
Rios , Movimentos da Água , Mudança Climática , Ecologia , Água
9.
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
10.
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
11.
Environ Monit Assess ; 193(10): 651, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34523026

RESUMO

Delivery of ecosystem services is strongly affected by changes in the land use/land cover (LULC) of an area. In this study, we analyze spatiotemporal changes in LULC of the rapidly changing Bagmati River Basin (BRB) of Nepal during 1988-2018 using Landsat satellite images. We also quantify carbon storage in different physiographic regions and LULC classes using the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model and assess economic valuation of carbon using the benefit transfer method. According to our analysis, there were increases in urban/built-up (247.5%), barren land (109.5%), shrub land (32.4%), and declines in forest cover (- 6.2%), cultivated land (- 4.1%), waterbodies (- 30.3%), sand (- 29.2%), and grass cover (- 10.6%) during the study period. As a result of these changes in LULC, carbon storage declined from 31.4 million tons year-1 in 1988 (worth 157.0 million USD) to 30.8 million tons year-1 (154.1 million USD) in 2018 with the total loss of 2.9 million USD. The largest decline in stored carbon was observed in Tarai and Dun valleys, from 6.8 to 6.5 million tons (- 1.4 million USD) followed by Churia, from 7.8 to 7.6 million tons (- 1.1 million USD). Increases in carbon storage were observed in urban/built-up and shrub land areas and declines in cultivated land, forest, barren land, waterbodies and grass land. The results of LULC change and estimated carbon stock in BRB provides a baseline for planners and policy makers to formulate appropriate plans to sustainably manage the region's land cover and to mitigate carbon loss.


Assuntos
Ecossistema , Rios , Conservação dos Recursos Naturais , Monitoramento Ambiental , Nepal
12.
Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi ; 33(4): 365-372, 2021 Aug 19.
Artigo em Chinês | MEDLINE | ID: mdl-34505443

RESUMO

OBJECTIVE: To investigate the current distribution of ticks and predict the suitable habitats of ticks in the Yangtze River Delta urban agglomeration in 2017, so as to provide insights into tick control and management of tick-borne diseases in these areas. METHODS: All publications pertaining to tick and pathogen distribution in the Yangtze River Delta urban agglomeration were retrieved, and the geographical location of tick distribution was extracted. The effects of 19 climatic factors on the distribution of ticks were examined using the jackknife method, including the mean temperature of the wettest quarter, precipitation of the coldest quarter, mean temperature of the driest quarter, maximum temperature of the warmest month, precipitation of the driest month, minimal temperature of the coldest month, annual precipitation, mean daily temperature range, precipitation seasonality, annual temperature range, temperature seasonality, annual mean temperature, mean temperature of the warmest quarter, precipitation of the wettest quarter, isothermality, mean temperature of the coldest quarter, precipitation of the wettest month, precipitation of the driest quarter and precipitation of the warmest quarter. The distribution of ticks was analyzed in 2020 using the maximum entropy (MaxEnt) model, and the potential suitable habitats of ticks were predicted in 2070 using the MaxEnt model based on climatic data. RESULTS: A total of 380 Chinese and English literatures were retrieved, and 148 tick distribution sites were extracted, with 135 sites included in the subsequent analysis. There were 7 genera (Haemaphysalis, Rhipicephalus, Ixodes, Dermacentor, Boophilus, Hyalomma and Amblyomma) and 27 species of ticks detected in the Yangtze River Delta urban agglomeration. The climatic factors affecting the distribution of ticks in the Yangtze River Delta urban agglomeration mainly included the mean temperature of the wettest quarter and the precipitation of the coldest quarter, with 26.1% and 23.6% contributions to tick distributions. The high-, medium- and low-suitable habitats of ticks were 20 337.08, 40 017.38 km2 and 74 931.43 km2 in the Yangtze River Delta urban agglomeration in 2020, respectively. The climate changes led to south expansion of the suitable habitats of ticks in the Yangtze River Delta urban agglomeration in 2070, and the total areas of suitable habitats of ticks was predicted to increase by 18 100 km2. In addition, the high-, medium- and low-suitable habitats of ticks were predicted to increase to 24 317.84, 45 283.02 km2 and 83 766.38 km2 in the Yangtze River Delta urban agglomeration in 2070, respectively. CONCLUSIONS: Multiple tick species are widespread in the Yangtze River Delta urban agglomeration, and the future climate changes may lead to expansion of tick distribution in these areas.


Assuntos
Ixodes , Rios , Animais , Mudança Climática , Ecossistema , Temperatura
13.
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
14.
J Hazard Mater ; 416: 126168, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492944

RESUMO

As an issue of great concern, microplastics pollution has emerged as a key environmental challenge of our time. The atmosphere is a significant compartment in the global cycle of microplastics, however, studies on the transport and deposition of airborne microplastics is limited. In the present work, atmospheric wet and dry deposition of microplastics were analyzed over one year in an urban environment of megacity Guangzhou, China. The atmospheric deposition fluxes of microplastics ranged from 51 to 178 particles/m2/d (mean: 114 ± 40 particles/m2/d). Fibers, fragments, films and microbeads were observed in the deposition samples, with fibers being the most abundant microplastics, accounting for 77.6 ± 19.1% of the total. The chemical composition of microplastics were identified using micro Fourier transform infrared spectrometer. 78.7% of the fibrous microplastics were derived from petrochemicals and most were polyethylene terephthalate (polyester), suggesting that textiles (e.g., clothes and curtains) were likely the main source. The results of back-trajectory analysis indicated that city rivers may act as secondary sources of airborne microplastics. Though no significant correlation was found between atmospheric microplastic deposition and meteorological factors such as rainfall and wind events, these factors were suggested to be positive drivers for the transport and deposition of airborne microplastic.


Assuntos
Microplásticos , Poluentes Químicos da Água , Atmosfera , Monitoramento Ambiental , Plásticos , Rios , Poluentes Químicos da Água/análise
15.
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
16.
Talanta ; 235: 122738, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517606

RESUMO

Heavy metal speciation and distribution is significantly influenced by dissolved organic matter (DOM) exhibited in ecosystems, particularly in urbanized rivers. Synchronous fluorescence spectroscopy (SFS) conjunct second derivative and two-dimensional correlation spectroscopy (2D-COS) was devoted to characterizing interactions of DOM-copper (II). Three typical water samples were collected from Baitapu River. Only protein-like fluorescence (PLF) and fulvic-like (FLF) were identified from the SFS. Stability constant (log K) values of PLF complexes with copper (II) varied from 4.277 to 5.833, and proportion of binding fluorescent materials (f) were 0.054-2.640. The log K values of FLF complexes with copper (II) varied from 3.996 to 4.243, while the f values were 0.001-0.036. Obviously, PLF had much stronger complexing capacity than FLF. There were four obvious peaks in the principal component analysis and second derivative fluorescence spectroscopy (SDFS), i.e., tyrosine-like (TYLF), tryptophan-like (TRLF), microbial humus-like (MHLF) and FLF. The log K values of TYLF and TRLF complexes were 4.899-5.907 and 4.598-5.831, respectively, which were similar to those from PLF. The log K values of MHLF complexes varied from 4.311 to 5.760, and the f values were 0.261-8.688. The log K values of FLF complexes were ranged from 4.598 to 5.831, which were higher than those deduced from the SFS. Interestingly, by the SDSF, PLF was divided into TYLF and TRLF, which increased the parameters values from DOM-copper (II) complexes. 2D-SFS-COS revealed that the TRLF was more susceptive response to copper (II) appended than TYLF, MHLF, and FLF. Moreover, TYLF and TRLF could priorly interact with copper (II). The SDSF conjunct 2D-COS could be effective approaches for insight into the complexing heterogeneity of DOM with copper (II). The study could present a support to preventing heavy metals and organic pollution in urbanized rivers.


Assuntos
Cobre , Rios , Ecossistema , Substâncias Húmicas/análise , Espectrometria de Fluorescência
17.
Environ Monit Assess ; 193(10): 656, 2021 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-34532822

RESUMO

The chemical characterization and assessment of the water quality in the headwater areas of the Himalaya are necessary for securing the water in the future. This study aims to assess the hydrochemistry and water quality concerning drinking and irrigational uses in the Seti River Basin (SRB), Nepal. A total of 45 water samples were collected in 2016 from the SRB during pre-monsoon, monsoon, and post-monsoon seasons, and pH, EC, TDS, and DO were measured on-site, whereas Ca2+, Mg2+, K+, Na+, Cl-, SO42-, NO3-, and dissolved Si were analyzed in the laboratory. The results revealed mildly alkaline pH (8.40 ± 0.43) with the pattern of average ionic dominancy: Ca2+ > Mg2+ > Na+ > K+ and HCO3- > SO42- > Cl- > NO3- for cations and anions, respectively. Gibbs diagram implied that the lithogenic weathering mainly controlled the solute acquisition process, which was further confirmed by the Piper diagram, exhibiting Ca-HCO3 as the governing hydrochemical facies (91%). The average molar ratios were 0.88, 8.33, and 6.86 of (Ca2+ + Mg2+)/TZ+, (Ca2+ + Mg2+)/(Na+ + K+), and HCO3-/(Na+ + K+), respectively, which specified that the carbonate weathering largely controlled the solute acquisition processes with a minor contribution of silicates. The mass budget calculation also confirmed the dominance of carbonate weathering (72.0%, 78.9%, and 62.0% in Pre-Monsoon, Monsoon, and Post-Monsoon, respectively) and the high monsoon rainfall's dilution effect to anthropogenic input of cations. Principal component analysis and correlation matrix exhibited that the major sources of ions in the basin were geogenic with minor anthropic signatures. Furthermore, water quality in connection to drinking and irrigation uses revealed that the basin has mostly retained its natural water quality. This investigation suggests that regular monitoring and assessment are essential for maintaining the water quality and ecological integrity in the Himalayan river basins.


Assuntos
Água Subterrânea , Poluentes Químicos da Água , Monitoramento Ambiental , Nepal , Rios , Poluentes Químicos da Água/análise , Qualidade da Água
18.
Environ Monit Assess ; 193(10): 666, 2021 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-34545422

RESUMO

Lead (Pb) is a potentially toxic element with significant environmental interest. Simple and sensitive analytical methods are necessary to allow determination of this element at trace levels using sample preparation procedures related to green chemistry. For this, calcium alginate beads (CA-beads), a low-cost and environmentally friendly biopolymer, have been proposed for extraction and preconcentration of Pb2+ in river water samples and determination by flame atomic absorption spectrometry (FAAS). CA-beads were prepared and applied to extract and preconcentrate Pb2+ in river water samples, providing an enrichment factor (EF) of 50, enhancement factor (E) of 54, a detection limit of 2 µg L-1, and a relative standard deviation < 5%. The extraction of Pb2+ in CA-beads achieved good selectivity, with recoveries from 94.8 to 100.2% in real samples, demonstrating the good accuracy of the proposed method. The results were also compared to those obtained by ICP-MS. The reuse of CA-beads was evaluated for six cycles, and under these conditions, the extraction and preconcentration efficiency of Pb2+ were not significantly affected. The developed methodology was applied to determine Pb2+ in water samples from rivers that are part of the hydrographic areas of Tibagi and Pitangui Rivers, in which the Pb2+ concentration was less than 2 µg L-1, a concentration lower than that established by Brazilian legislation for class I and II rivers.


Assuntos
Chumbo , Poluentes Químicos da Água , Alginatos , Monitoramento Ambiental , Estudos de Viabilidade , Concentração de Íons de Hidrogênio , Rios , Espectrofotometria Atômica , Água , Poluentes Químicos da Água/análise
19.
Artigo em Russo | MEDLINE | ID: mdl-34486862

RESUMO

The specificity of course of acute period of craniocerebral injury and organization of medical care support are the factors determining outcomes for this category of patients. The purpose of the study is to investigate changes in predictors of course of acute period course of craniocerebral injury under implementation of stream model of medical care organization. The sampling included 150 patients with moderate and severe craniocerebral injury based on data obtained in 2013 and 2019, respectively. The clinical characteristics of patients (gender, age, level of consciousness, alcoholic intoxication, type of injury) and the characteristics of organization of medical care (mode of admission, qualification of hospital physician, time prior to surgery intervention) were evaluated. The selection of predictors significant for prognosis of outcomes of acute period of craniocerebral injury was implemented on the basis of logit-regression analysis and artificial neural network technology. The sampling of patients was divided into groups on the basis of outcomes of acute period of craniocerebral injury. The groups with relatively favorable and unfavorable course of acute period of craniocerebral injury were identified. It is demonstrated that prior to implementation of stream model of medical care provision, the most significant factors determining outcomes of the acute period of craniocerebral injury were characteristics of organization of medical care of these patients. After implementation of stream model the leading predictors became clinical characteristics of patients.


Assuntos
Traumatismos Craniocerebrais , Rios , Traumatismos Craniocerebrais/diagnóstico , Traumatismos Craniocerebrais/epidemiologia , Traumatismos Craniocerebrais/terapia , Hospitalização , Humanos , Prognóstico
20.
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
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