نتایج جستجو برای: sediment sources

تعداد نتایج: 323946  

2011
A. Mark Ibekwe Shelton E. Murinda Alexandria K. Graves

Agricultural and urban runoffs may be major sources of pollution of water bodies and major sources of bacteria affecting the quality of drinking water. Of the different pathways by which bacterial pathogens can enter drinking water, this one has received little attention to date; that is, because soils are often considered to be near perfect filters for the transport of bacterial pathogens thro...

1999
H. T. S. Boschker J. F. C. de Brouwer T. E. Cappenberg

Stable carbon isotope ratios of bacterial biomarkers were determined to infer sources of organic carbon used by bacteria in the sediments of three salt marshes. Biomarkers studied were polar lipid-derived fatty acids (PLFA), mainly bacteria-specific, methyl-branched i15 : 0 and a15 : 0. Experiments showed that isotopic fractionation between substrate and biomarkers was relatively constant (24 t...

2011
Upal Ghosh Richard G. Luthy Gerard Cornelissen David Werner Charles A. Menzie

A sediments form the ultimate repositories of past and ongoing discharges of hydrophobic organic compounds (HOCs) such as polychlorinated biphenyls (PCBs), many pesticides, and dioxins, as well as mercury (Hg) and methylmercury (MeHg). These sediment-bound pollutants serve as longterm exposure sources to aquatic ecosystems. Approximately 10% of the sediment underlying the United States' surface...

2009
Carly Stevens

14 15 Rare earth element oxides (REOs) have excellent potential for use as tracers in 16 erosion studies. Using laboratory and field experiments we aimed to develop and test 17 a simple application method for spreading REOs and to use REOs to determine the 18 source of sediment to concentrated overland flow paths. 19 Tracks left by farm machinery (tramlines) in fields act as concentrated flow 2...

Ships transport about 80 percent of world trade and transfer approximately three to five billion tons of ballast water internationally every year. Due to the likely presence of pollutants, the ballast water discharged by ships can have negative effects on aquatic ecosystems. This study was conducted on 10 ships that entered the Bushehr port to determine the effectiveness of the ballast water ex...

قدرتی, علیرضا, نظامی, محمد طاهر,

Generally the negative affects of any component part of a Watershed can evaluate in the intensity of its produced sediment and erosion. In any basin, the erosion amount is more than sediments, becase of eroded materials in the basin due to natural sedimentary traps. Therefore it is necessary to detemine the relationship between coefficent of sedimentation and physical parameters of any basin fo...

2016
M. C. Ong F. M. Fok K. Sultan B. Joseph

Geochemical sediment of the tropical Pinang River, Malaysia was carried out with the aim at documenting elemental concentrations and pollution level assessment. Concentration of selected heavy metals (Cu, Cd, Cr, Pb, Zn and Mn), rare earth elements, TOC and grain size distribution of sediments were determined at 100 m sampling interval along the river. Sediment size showed a positive correlatio...

2007
C. H. Vane I. Harrison A. W. Kim

Sediments from the Mersey Estuary were analysed for polycylic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Total PAH concentrations ranged from 626 to 3766 μg/kg and total PCB concentrations ranged from 36 to 1409 μg/kg. These concentrations are intermediate in comparison to other U.K estuaries with similar histories of industrialisation and urbanisation. The distribution ...

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