نتایج جستجو برای: urmia lake sediments
تعداد نتایج: 69393 فیلتر نتایج به سال:
A dredged material disposal operation was monitored on a location in Lake Erie 8 km offshore Ashtabula, Ohio, June to November, 1975. Some 200 sediment cores were collected in the periods before and after dredging and analyzed for the grain-size distribution of the sediments. Two current meters and a wave sensor moored nearby monitored the movement of the water masses. The sediments were dredge...
Particle size analysis of lacustrine core sediments and atmospheric natural dust were conducted in the drainage area of Ebinur Lake in arid northwest China. Using a combination of (137)Cs and (210)Pb dating, a continuous record of aeolian transportation to the lake sediments and related factors over about the past 150 years was analyzed. Factor analysis revealed the particle-size distributions ...
A detailed understanding of the formation of the potent neurotoxic methylmercury is needed to explain the large observed variability in methylmercury levels in aquatic systems. While it is known that organic matter interacts strongly with mercury, the role of organic matter composition in the formation of methylmercury in aquatic systems remains poorly understood. Here we show that phytoplankto...
Historical records of mercury (Hg) accumulation in lake sediments and peat bogs are often used to estimate human impacts on the biogeochemical cycling of mercury. On the basis of studies of lake sediments, modern atmospheric mercury deposition rates are estimated to have increased by a factor of 3-5 compared to background values: i.e., from about 3-3.5 microg Hg m(-2) yr(-1) to 10-20 microg Hg ...
heavy metal concentrations in surface water, wastewater and sediments collected from mighan lake in markazi province, iran were analyzed, and assessment contamination were evaluated according to the water and sediment quality guidelines. the results showed that the average concentrations of heavy metals in water were ranked as: ni> cr> pb> fe> cu> zn. in comparison with results the background v...
Concentrations and stable isotope ratios of lead (Pb) from lake sediments were used to quantify temporal patterns of anthropogenic Pb pollution in the Clyde River region of Baffin Island, Arctic Canada. Surface sediments from eight lakes on eastern Baffin Island and one from northern-most Greenland, spanning a gradient of 20 degrees latitude, showed great variability with respect to Pb concentr...
We have studied the magnetic properties of wet and dry late Pleistocene Lake Lisan sediments and the Holocene Dead Sea sediments. Our initial prediction was that the properties of both would be quite similar, because they have similar source and lake conditions, unless diagenetic change had occurred. Rock magnetic and paleomagnetic experiments revealed three stages of magnetization acquisition....
Polyphosphate is a quantitatively important and dynamic component of the sedimentary phosphorus in many lakes. Kenney et al. correctly note that we misrepresented their data on polyphosphate in Lake Apopka in our article on the phosphorus composition of subtropical lake sediments, and we regret this error. However, we reiterate that their operationally defined heat extraction procedure overesti...
We used the bacterial test on the cells called Arthrobacter globiformis in order to detect the level of toxins in the sediment of the Lake Skadar. We kept an eye on the influence of the sediments on the activity of the whole of bacterial dehydrogenase (DNA) by the process of the reduction of the oxidoreduction color of the resasurine into the resofurine. We used the organic fraction of the sedi...
GIS-based ordered weighted averaging and Dempster–Shafer methods for landslide susceptibility mapping in the Urmia Lake Basin, Iran Bakhtiar Feizizadeh a b , Thomas Blaschke a & Hossein Nazmfar c a Department of Physical Geography, Centre for Remote Sensing and GIS, University of Tabriz, Tabriz, Iran b Department of Geoinformatics (Z_GIS), University of Salzburg, Salzburg, Austria c Department ...
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