نتایج جستجو برای: lake sediment
تعداد نتایج: 75775 فیلتر نتایج به سال:
A highly chlorinated flame retardant, Dechlorane Plus (DP), was detected and identified in ambient air, fish, and sediment samples from the Great Lakes region. The identity of this compound was confirmed by comparing its gas chromatographic retention times and mass spectra with those of authentic material. This compound exists as two gas chromatographically separable stereoisomers (syn and anti...
The Selenga River Delta, Lake Baikal, Russia, is ~600 km2 in size and contains multiple distributary channels that receive varying amounts of water and sediment discharge. The delta is positioned along the deep-water (~1600 m) margin of Lake Baikal, a half-graben–styled rift basin, qualifying it as a modern analogue of a shelf-edge delta system. This study provides a detailed field survey of ch...
Recent Lake Tanganyika Hg deposition records were derived using C and excess Pb geochronometers in sediment cores collected from two contrasting depositional environments: the Kalya Platform, located mid-lake and more removed from watershed impacts, and the Nyasanga/Kahama River delta region, located close to the lake’s shoreline north of Kigoma. At the Kalya Platform area, pre-industrial Hg co...
Parts of the sandy littoral sediment of a Precambrian shield lake (Lake 302s) were intermittently covered with a layer of flocculent organic-rich material l-20 mm thick. Sandy sediments with flocculent surface sediment had higher rates of respiration (31-105%) and photosynthesis (37224%) than those without. Densities of invertebrate macrofauna were 10 times higher in the flocculent surface sedi...
The rate of sediment supply from erosional catchment to depositional basin depends primarily upon climate, relief, catchment slope and lithology. It varies in both time and space. Spatial changes in erosion rates due to variations in lithology are illustrated by contrasting rates of drainage divide migration away from faults of known ages. Time variations in relative sediment supply are extreme...
After significant reductions in external phosphorus (P) loads, and subsequent water quality improvements in the early 1980s, the water quality of Lake Erie has declined considerably over the past decade. The frequency and magnitude of harmful algal blooms (primarily in the western basin) and the extent of hypoxic bottom waters in the central basin have increased. The decline in ecosystem health...
The Nymphoides peltata (N. peltata) population has shown rapid expansion in Lake Taihu, China, in recent years. The core question is whether N. peltata seeds have contributed to the expansion. To address this, we randomly selected three N. peltata stands to investigate the seed bank characteristics of N. peltata in Lake Taihu. Results showed that N. peltata had high seed production, with a maxi...
Glacial Lake Missoula formed when the Purcell Trench lobe of the Cordilleran ice sheet dammed Clark Fork River in Montana during the Fraser Glaciation (marine oxygen isotope stage 2). Over a period of several thousand years, the lake repeatedly filled and drained through its ice dam, and floodwaters coursed across the landscape in eastern Washington. In this paper, we describe the stratigraphy ...
The release of P from lake sediments, which occurs as a part of internal loading, may contribute a significant portion of the total P load to a lake. Phosphorus release rates from sediments in Spring Lake, Michigan, and the degree to which alum reduces P release from these sediments, were investigated during the summer of 2003. Triplicate sediment cores were sampled from four sites in the lake,...
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