| Organic matter is one of the most important natural colloid in the sediment of heavy metals, organic pollutants such as absorption, distribution, complexation of active substance, is also reflect the sediment organic nutrition level of important symbol, the sediment organic matter degradation will make a large amount of dissolved oxygen in water is consumed, and is accompanied by a large amount of nitrogen and phosphorus nutrient release, increasing the risk of a lake endogenous release. Phosphorus is the main limiting factor for eutrophication in Taihu Lake and most shallow water lakes. Into the bottom part of phosphorus absorbed by aquatic plants, part of the dissolved in various forms in water, and part is through the physical,chemical and biological effect, the deposit on the bottom, after accumulating formed sediment. Researchs show that the amount of pollutants into Taihu Lake mainly by the river input, rivers with coastal industrial and agricultural non-point source pollution, and the impact of human activities, accumulate large amounts of nutrients,after input in Taihu Lake,lead to serious,Taihu Lake sediment siltation makes water pollution is serious, at the same time promote algae outbreak in Taihu Lake. This article through to the direction of rivers into the lake along the main river estuary sediment, total phosphorus and phosphorus speciation analysis aims to reveal the estuary sediment phosphorus migration characteristics, to understand western estuary provides the basis for the prevention and control of status quo and the eutrophication of taihu lake pollution data, The main area of research are Dagang River, Wuxi Port,Dapu Port, Miaodu Port, Chendong Port, Shedu Port, Shatang Port, Taige Canal.The main conclusions are as follows:(1) Estuary surface sediment into the lake each moisture content from 26.5% to 26.5%, its highest level in Dapu Port, moisture content is 80.42%, the lowest in Wuxi Port, moisture content of 26.5%. Generally speaking, the upper sediment (0 to 8 cm)moisture content is higher, mainly due to the surface for the new deposit more algae and other biological residues of high moisture content, from the surface down, and gradually reduce the moisture content, compaction.(2) The overall content of sediment organics in the west bank of Taihu lake was 1.93% to 7.32%, the highest point in the estuary of Shatang Port, at 7.32%. The lowest is Dagang River, which is 1.93%. From the near shore of the estuary to the lake district, the sediment load is gradually rising in the estuary, Dagang River,Dapu Port, Miaodu Port, Shatang Port, etc. The sediment load is slightly lower in the case of Chendong Port and Shedu Port, mainly due to the large amount of silt in the area this year. The content of organic matter increased and then reduce in Shatang Port, the reason may be due to the close into the lakes within the scope of terrigenous pollution and endogenous pollution work together, make content of organic matter increased,after deep lakes, terrestrial pollution influence gradually reduce, mainly endogenous pollution, to some extent, cut down the content of organic matter.On the vertical distribution, the surface and lower organic matter content of Wuxi Port is low, and the central content is higher. The organic matter distribution of the sediment in Dapu Port is low, and the organic matter increases as the depth increases.Most of estuarine sediment organic matter from the surface to the underlying volatility,there is no obvious change, but the overall content such as Miaodu Port, Shedu Port,Shatang Port and Taige Canal;From all the estuary of the distribution of the northwest coast of south between organic matter, in the northwest coast of clubs to blaspheme Shedu Port, the Shatang Port and Taige Canal canal river mouth area. The content of organic matter was significantly higher in what on the west coast, Dagang River, Wuxi Port , Chendong Port, Dapu Port and Miaodu Port, northwest of Taihu Lake polluted situation is more serious.(3) In surface sediment of main inflow rivers, the content of TP is between 303.74-1151.18 mg/kg, peak appears in the Shatang Port, 1151.18 mg/kg, the lowest in Wuxi Port, 303.74 mg/kg. From the northwest coast of Taihu Lake to the distribution of the estuary in the west coast, the content of the estuary is higher than the west coast. Dagang River belongs to a clean state, Shatang Port and Miaodu Port belong to light pollution, clubs to blaspheme Shedu Port, Shatang Port and Taige Canal are in severe pollution, mainly with a large population in northwest, industry and agriculture developed, terrigenous pollution is serious. There is a difference in the distribution of phosphorus in the surface sediments, which are related to the pollution type, geographical location and the prevailing wind in the lake.(4) The content of TP and its phosphorus form of sediment are in the vertical distribution, in general, from the surface to the bottom, the content of TP is decreasing,and the declining trend of estuary is very different. Decreases rapidly with Dapu Port,decline is not obvious in Dagang River, Chendong Port, Shedu Port and Miaodu Port,top-down fluctuations have a club to blaspheme port and Taige Canal. The Ca-P content is changed, and different river regions are different, mainly influenced by the pH of sediment in the river area and the characteristics of the characteristics of the Ca-P itself. The vertical distribution of the OP is affected by the roots and aquatic activities of the plants, and the distribution in each river area is different. Because of the shallow lakes endogenous release are different from the deep lakes mainly depends on the concentration gradient, hydrodynamic action not only make the shallow lakes sediment resuspension, and it is the important factors influencing the overlying water nutrient transformation of migration. Therefore,the complex and volatile wind waves and the lake flow may be the main reason for the inconspicuous distribution of nutrient salt in shallow water lakes.In summary,the distribution of phosphorus in the estuarine area showed a large difference, which is related to the factors such as the type of pollution, the geographical location and the prevalence of Taihu Lake. In general, the content of organic matter and phosphorus in the estuary of the northwest lake is higher than that in the western lake area. Therefore,to explore the mechanism of sediment transport and transformation in the estuary area, it should be combined with other indicators such as the pollution type and geographical location of the rivers, and we should pay attention to the nutrient enrichment in the northern estuary area. |
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