نتایج جستجو برای: sediment cores pollution
تعداد نتایج: 128525 فیلتر نتایج به سال:
The magnitude and ecological relevance of metal pollution from the upstream of water sources after emergency pollution events was investigated by applying a set of complementary sediment quality assessment methods: (1) geochemical assessment based on background value (the geoaccumulation index); (2) comparisons with sediment quality guidelines (SQGs); (3) an evaluation of the combined pollution...
We compared the stratigraphy of sediment cores that span the last 13,000 yrs from three sites in the main basin of Lake Titicaca, Boliva/Peru as indicators of regional paleoclimate. The cores show similar patterns of change after ~6,400 calendar yrs before present (cal yr BP) but differ before that time. Site NE98-PC2, which is near the Rio Illave and its delta, shows differences in diatom spec...
the mandovi estuary is highly influenced by mining and tourism related activities in the centralwest coast of india. vertical fluxes and accumulation of petroleum hydrocarbons (phcs) in three sedimentcores (d1, c1 and og) from the mandovi estuary were assessed using ultra-violet fluorescence (uvf)spectroscopy. the range of phcs values in estuarine sediments varied from 5.4 to 12.34 μg/g enrichm...
Patterns of microbial distribution represent the integrated effects of historical and biological processes and are thus a central issue in ecology. However, there is still active debate on whether dispersal limitation contributes to microbial diversification in strongly connected systems. In this study, sediment samples were collected along a transect representing a variety of seawater pollutio...
Mercury accumulation and attenuation at a rapidly forming delta with a point source of mining waste.
The Walker Creek intertidal delta of Tomales Bay, California is impacted by a former mercury mine within the watershed. Eleven short sediment cores (10 cm length) collected from the delta found monomethylmercury (MMHg) concentrations ranging from 0.3 to 11.4 ng/g (dry wt.), with lower concentrations occurring at the vegetated marsh and upstream channel locations. Algal mats common to the delta'...
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...
Heavily polluted sediment is becoming an important part of water pollution, and this situation is particularly acute in developing countries. Sediment has gradually changed from being the pollution adsorbent to the release source and has influenced the water environment and public health. In this study, we evaluated the pollutant distribution in sediment in a heavily polluted river and agitated...
This paper introduces a radiographic system for imaging marine sedimentary structures in situ, as an alternative to the currently used intrusive and tedious process of imaging extracted core samples in the laboratory. The system consists of a small isotopic source and a film incorporated into a device that can penetrate the sediment. The design of the device is introduced, and the results of mo...
As part of a study using lake sediments to determine the extent and causes of human impacts to lakes along an east–west transect following the Yangtse River, sediment cores were taken from Taihu in eastern China. Previous studies have focussed on the impacts of direct inputs of pollutants from municipal and industrial wastewater but little work has been undertaken on trends in atmospheric depos...
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