نتایج جستجو برای: sediment quality
تعداد نتایج: 786929 فیلتر نتایج به سال:
The Universal Soil Loss Equation (USLE) and its derivatives are widely used for identifying watersheds with a high potential for degrading stream water quality. We compared sediment yields estimated from regional application of the USLE, the automated revised RUSLE2, and five sediment delivery ratio algorithms to measured annual average sediment delivery in 78 catchments of the Chesapeake Bay w...
Sediment-quality assessment often is hindered by the lack of agreement between chemical and biological lines of evidence. One limitation is that the bulk sediment toxicant concentration, the most widely used chemical parameter, does not always represent the bioavailable concentration, particularly for hydrophobic organic compounds (HOCs) in highly contaminated sediments. In the present study, w...
Long-term changes of fish biotic integrity in the Sanmenxia Wetland, North China, since the 1950s were assessed using the fish index of biological integrity (FIBI). The water and sediment quality was evaluated by the water quality index (WQI) and sediment pollution index (SPI). The results showed that FIBI continuously decreased from 46 to 20 during the past 5 decades, which indicated that the ...
A 125-mile reach of the South River, Virginia, was contaminated with mercury during the first half of the 20th century. As increased concentrations of mercury have persisted, researchers have carefully studied its distribution in the river biota and estimated associated risks. The present study evaluated the influence of mercury on feeding rate and uptake by the amphipod Hyalella azteca. The te...
Natural geological conditions together with the impact of human activities could produce environmental problems due to high As concentrations. The aim of this study was to assess the role of epipsammic biofilm-sediment systems onto As (V) sorption and to evaluate the effect of the presence of equimolar P concentrations on As retention. A natural biofilm was grown on sediment samples in the labo...
Water quality modeling efforts for developing total maximum daily loads often use geographical information system data of varying quality in watershed-scale models and have shown varying impacts on model results. Several streams in the southern Piedmont are listed for sediment total maximum daily loads. The objective of this study was to test the effect of spatial resolution of soil data on the...
This article is the second in a series of three that describes the results of a Natural Resource Damage Assessment (NRDA) conducted in the Grand Calumet River and Indiana Harbor Area of Concern (IHAOC). The assessment area is located in northwest Indiana and was divided into nine reaches to facilitate the assessment. This component of the NRDA was undertaken to determine if fish and wildlife re...
Organochlorine pesticides (OCPs), viz. β-hexachlorocyclohexane (β-HCH), γ-HCH, aldrin, dieldrin, endrin, heptachlor, endosulfan-I, endosulfan-II, heptachlor endoepoxide, heptachlor exoepoxide, mirex, dicofol, o,p'-dichlorodiphenyltrichloroethane (o,p'-DDT), p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT), dichlorodiphenyldichloroethane (DDD), and dichlorodiphenyltrichloroethylene (DDE) and 12 o...
The hatching of cladoceran ephippia from a 15-cm long sediment core was investigated, and Ceriodaphnia quadrangula clones were isolated from different sediment layers. Bosmina microfossil data were also analyzed, and compared with the corresponding data from a Pb210 dated core, which allowed us to infer the age of the sediment layers. Using changes in Bosmina microfossil morphologies, we were, ...
The pollution level of Lake Bafa was investigated by collecting fish samples {Dicentrarchus labrax (sea bass), Liza ramada (mullet) and Anguilla anguilla (eel)}, surface sediment, and core samples. In all these samples, 210Po and 210Pb concentrations were estimated, and total annual dose rates were obtained for each species. Some heavy metal (Cr, Ni, Pb, Cd, Mn, Fe, and Zn) concentration levels...
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