نتایج جستجو برای: sediment core
تعداد نتایج: 250295 فیلتر نتایج به سال:
Mercury deposition histories have been scarcely documented in the southern hemisphere. A sediment core was collected from the ecologically important estuarine floodplain of the Berg River (South Africa). We establish the concentration of Hg in this (210)Pb-dated sediment core at <50 ng g(-1) Hg(T) throughout the core, but with 1.3 ng g(-1) methylmercury in surface sediments. The (210)Pb dating ...
In this data article, by using inductively coupled plasma optical spectrometry (ICP-OES), we aimed to (1) determine the concentration levels of As, Ag, Sr, Sn, Sb, and Mo in the sediments and the shells of Trachycardium lacunosum simultaneously in two separated areas (unpolluted and polluted areas) (2) comparison between the metal contents of sediments in the unpolluted and polluted areas as we...
Eutrophication is a water quality issue in lakes worldwide, and there is a critical need to identify and control nutrient sources. Internal phosphorus (P) loading from lake sediments can account for a substantial portion of the total P load in eutrophic, and some mesotrophic, lakes. Laboratory determination of P release rates from sediment cores is one approach for determining the role of inter...
Phosphorus inputs into reservoirs include external sources from the watershed and internal sources from the reservoir bottom sediments. This study quantified sediment P flux in Lake Eucha, northeastern Oklahoma, USA, and evaluated the effectiveness of chemical treatment to reduce sediment P flux. Six intact sediment-water columns were collected from three sites in Lake Eucha near the reservoir ...
A 10Be/9Be-based chronostratigraphy has been determined for ODP 181, Site 1121 sediment core, recovered from the foot of the Campbell Plateau, Southwest Pacific Ocean. This core was drilled through the Campbell ‘skin drift’ in ca. 4500 m water depth on the mid-western margin of the extensive Campbell Nodule Field, beneath the flow of the major cold-water Deep Western Boundary Current (DWBC). In...
از جمله معروفترین آنتی بیوتیکهای ضدسرطان، می توان به آدریامایسین دانومایسین و اکتینومایسین d اشاره کرد. این داروها در معالجه سرطان از طریق شیمی درمانی مودر استفاده قرار می گیرند. هدف اصلی این داروها در سلول، مولکول dna است . از آنجا که مولکول dna در داخل هسته سلول به صورت برهنه و آزاد نیست بلکه در اتصال با ترکیبات دیگری مثل پروتئین های هسیتونی و غیرهیستونی می باشد، میان کنش این داروها با پروتئی...
Sediment variables total organic carbon (TOC), total nitrogen (TN), total sulfur (TS), as well as their accumulation rates and atomic ratios (C/N and C/S), were studied along with stable isotopes (δ 13 C, δ 15 N, and δ 34 S), and specific biomarkers (n-alkanes and pigments) in a 35-cm-long sediment core from Lake Bhimtal, NW India. The average sedimentation rate is 3.6 mm yr -1 , and the core r...
Gamma spectroscopy was used for determination of radionuclides in sediment cores from the continental shelf off NW Africa to provide age control of the sediment record used for a study of aridification of the Sahel zone. Pb, Ra and Cs were measured in the upper part of a gravity core and the associated multicorer and used for aligning these cores. This provided information about the amount of s...
[1] The paleoceanographic recording fidelity of pelagic sediments is limited by chemical diagenesis and physical mixing (bioturbation and horizontal sediment transport). Diagenesis and bioturbation are relatively well-studied, but the effects of physical sedimentation have been largely ignored. Modeling U series isotopes (e.g., Th) can potentially quantify horizontal sediment movement, but mode...
Denitrification is commonly measured using in situ benthic chambers or laboratory incubations of sediment cores. These techniques are similar in principle but differ considerably in cost and practicality. Despite widespread use of both techniques, it is uncertain whether they give comparable results. We compared cores and chambers for measuring fluxes (dissolved oxygen [DO], N2, NH4, NO3 and NO...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید