نتایج جستجو برای: surface sediments
تعداد نتایج: 658804 فیلتر نتایج به سال:
Bacterial community structures were evaluated in oil samples using culture-independent pyrosequencing, including oil mousses collected on sea surface and salt marshes during the Deepwater Horizon oil spill, and oil deposited in sediments adjacent to the wellhead 1 year after the spill. Phylogenetic analysis suggested that Erythrobacter, Rhodovulum, Stappia, and Thalassospira of Alphaproteobacte...
Some physico-chemical properties and the concentrations of the metals Fe, Mn, Ni, Cd, Cr, Co, Cu, Pb, and Zn in water and sediments were examined from September 2011 to January 2012 in Bodo Creek, where oil spills have been recurrent. Temperature, pH, total dissolved solid, conductivity, salinity, dissolved oxygen, biological oxygen demand (BOD), chemical oxygen demand (COD), total hardness, su...
An overall and comparative ecological risk assessment of heavy metal pollution (including Cu, Zn, Pb, Cd, Hg, Cr, As, and Ni) in surface sediments was conducted for six major shallow freshwater lakes (Taihu Lake, Chaohu Lake, Nansihu Lake, Dongting Lake, Poyang Lake, and Hongze Lake) in China. A spatial database with 339 sediment samples was created through an extensive literature survey. Conse...
Surface sediments are important systems for the removal of anthropogenically derived inorganic nitrogen in estuaries. They are often characterized by the presence of a microphytobenthos (MPB) biofilm, which can impact bacterial communities in underlying sediments for example by secretion of extracellular polymeric substances (EPS) and competition for nutrients (including nitrogen). Pyrosequenci...
Background and Objective: Mercury (Hg) is considered as a global pollutant that is widely dispersed in the environment. Monitoring of total mercury (THg) concentration in the sediments without determination of organic mercury (OHg) and selenium (Se) is an unreliable approach to evaluate the precise toxicological effects of Hg. In the present study, concentrations of THg, OHg and Se in the surfa...
Mercury (Hg) is a toxicant of global concern that accumulates in organisms as methyl Hg. The production of methyl Hg by anaerobic bacteria may be limited in anoxic sediments by the sequestration of divalent Hg [Hg(II)] into a solid phase or by the formation of elemental Hg [Hg(0)]. We tested the hypothesis that nanocrystalline mackinawite (tetragonal FeS), which is abundant in sediments where H...
Fiber-optic microprobes for determining irradiance and scalar irradiance were used for light measurements in sandy sediments of different particle size. Intense scattering caused a maximum integral light intensity [photon scalar ~rradiance, E"(400 to 700 nm) and Eo(700 to 880 nm)] at the sediment surface ranging from 180% of incident collimated light in the coarsest sediment (250 to 500 pm grai...
Grain-size analysis has long been used as a descriptor of transport and depositional processes. This paper presents the possibility of using image-based granulometries, not yet widely used in the earth sciences, to characterize granulometric composition of unconsolidated estuarine and marine sediments. To test the method, conventional sediment analysis of siliceous and calcareous sediments are ...
Background and Aim:This research was conducted of determining and comparing the heavy metals of zinc, iron, manganese, copper, nickel and vanadium in summer in waters and sediments of Naseri wetland in Khuzestan province, 2017. Material and Methods:Sampling of water and sediments from three areas of north, central and southern Naseri wetland was carried out in summer. In order to measure heavy...
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