Subei Plain River Network Area Typical River Sediment Pollution Occurrence Characteristics Research

Increasingly the water in northern part of Jiang Su plat plain river eutrophicated, and the same phenomena were found to be present in some rivers, showing that the overall water pollution situation was not optimistic, especially small and medium-sized river water pollution was serious. River sediment was like water pollution history "record", not only reflecting the river water pollution, but also effectting the interface of river water through the physical and chemical actions between the mud and overlying water. She Yang in Yan Cheng of this study, as the survey region of the northern part of Jiang Su plat plain. Selecting the Sheyang river, Huangsha port, Xinyang Port and another8rivers as representative of "watershed" rivers, choosing Yunmian River, Tongyang river, Yunliang River, and Limin River and another8rivers as representative of regional rivers, selecting the Chuansha River, Center River, Jiangnan River, Zhanbei River and another17rivers as representative of "large ditches", and setting15rivers as the representative of "middle ditches", and then the sediment samples were collected and studied. The thesis mainly researched the occurrence characteristics of sediment nutrients, Phosphorus Fractionations, as well as the adsorption/desorption of P of the sample sites, by means of collecting48different types of river sediment samples, and conducted risk assessment in heavy metal (Ni,Pb,Cr, Cd,Zn,Cu, Mn) continually. Main conclusions were as following:(1)With the river size increasing, the content of total nitrogen (TN) became smaller in sediments of four different levels rivers, which content was from718.71mg/kg to1949.56mg/kg. There was a very significant correlation between the content of organic matter (OM) and nitrogen (TN)(p<0.01), with a negative correlation between sediment pH and total nitrogen content (TN)(p<0.05).The total concentration of phosphorus (TP) in the sediment ranged from1244.25mg/kg to2091.12mg/kg. With the decrease of the river scale, the total phosphorus (TP) got reduced gradually because of the non-point source pollution which is mainly caused by human activities.(2) The largest part of phosphorus was bound to calcium which was mainly extracted by HC1(HC1-TP) and residue phosphorus having stable state in the natural condition, and both the content of which were more than80%of the total phosphorus as well. The biological activity of phosphorus extracted by NaHCO3(NaHCO3-TP) and the Fe-Al combination of NaOH extractable phosphorus (NaOH-TP) were less, accounting for9.3%to17.3%of the total phosphorus content in the sediment. Total phosphorus (TP) and the biological activity of phosphorus extracted by NaHCO3(NaHCO3-TP), calcium bound phosphorus (HCl-TP) Fe-Al combination of NaOH extractable phosphorus (NaOH-TP) and residual phosphorus was showing very significantly relations,with the relevant order:residual phosphorus> NaHCO3-TP> HCl-TP and NaOH-TP.(3) In the condition of high initial P concentration, isotherms for P sorption onto uperficial sediments of rivers belonging to Jiang Su plat plain did not accord with the Langmuir isotherm as well as the Freundlich isotherm. The phosphate adsorption isotherms on sediments from rivers were fitted by Linear model in low initial phosphorus concentration, and calculate the phosphorus adsorption-desorption equilibrium concentration on sediment from rivers. The result indicated that the concentration of phosphorus adsorption-desorption equilibrium was among0.100mg/kg to0.515mg/kg. The concentration of phosphorus adsorption-desorption equilibrium of Watershed rivers was highest, when the concentration of phosphorus of local runoff did not exceed0.515mg/L, causing the sediment released phosphorus to overlying water and the sediment would turn the "source" to the surface runoff; The concentration of phosphorus adsorption-desorption equilibrium of Regional rivers was0.320mg/kg, which was lower than that of Watershed rivers. in addition, the concentration of surface runoff was normal and relatively low; The concentration of phosphorus adsorption-desorption equilibrium of Large ditches and Middle ditches were pretty less of the two kinds rivers mentioned above. When the concentration of phosphorus of local farmlands surface runoff was in advance of the concentration of phosphorus adsorption-desorption equilibrium, the sediment of the ditches could absorb phosphorus leading to the sediment become the "sink" of the phosphorus in surface runoff. The phosphorus adsorption capacity of Large ditches and Middle ditches was the primary mechanism for holders in plain river network region, also it was an important guarantee of river-surface water quality of the environment.(4) The order of heavy metal pollution of river was:Large ditches>Watershed rivers> Regional rivers>Middle ditches. Combining the NOAA sediment evaluation guidelines with Lake Ontario sediment evaluation criteria, it was easy to get a conclusion of heavy metal pollution that were such as:Cr> Cd>Ni>Cu>Pb>Zn>Mn. The concentration of Cr was the highest among the7heavy metals, which should be strengthen the management and control.