洪泽湖不同入湖河流沉积物磷形态特征及生物有效性

为揭示洪泽湖入湖河流沉积物磷形态空间差异性及影响因素，分析了洪泽湖自西北向西南7条入湖河流65个表层沉积物中不同磷（P）形态，并探讨了磷形态空间赋存特征的影响因素及环境意义.研究表明：沉积物总磷（TP）含量为488.90mg/kg~960.22mg/kg，无机磷（Pi）为主要形态，相对含量为65.81%~76.16%.西部入湖流域沉积物有机磷（Po）以非活性有机磷（NLOP）为主，汴河最高，相对含量约占Po的50.41%，生物有效态无机磷（BAP）相对含量最高，占Pi的66.84%，污染程度最高；西南和西北入湖流域Po则以中活性有机磷（MLOP）为主，Pi以钙结合态无机磷（HCl-Pi）为主.西北入湖流域由于受当地地质背景的影响，HCl-Pi所占Pi相对含量最高（43.02%），从而减缓了磷的移动能力，污染程度最低.随着沉积物污染程度的增加，生物有效态Po含量增加，但所占Po相对含量降低；HCl-Pi含量增加，所占Pi相对含量降低，这一现象和我国其它典型地区沉积物磷形态空间分布类似.西部和西南入湖流域主要受水土流失、有机面源污染及藻类生长的影响，有机质环境较高，水交换能力弱，可被有机质降解的Po组分高于可被矿化的Po组分，大部分难降解Po组分易沉积，导致西部和西南入湖流域较高的BAP和NLOP含量，富营养化程度较高.沉积物OM是各形态磷之间相互转化的关键因素，和沉积物内源磷地球生物化学循环密切相关.洪泽湖入湖流域沉积物磷形态空间差异性主要由农业面源污染物的输入而导致内源磷负荷加剧.洪泽湖西部和西南入湖流域应重点控制农田水土流失及养殖业面源污染，建设滨岸修复带，遵循少量多次增施有机肥原则，减少农用地水土流失.健全农村养殖业废水废渣处理；划定科学养殖区；提倡铜围网箱，增加水体交换率.而对于洪泽湖西北入湖流域则应重点防止过度城镇化带来的水土流失及对生态功能保护区过高的污染负荷.

Characteristics and bioavailability of different forms of phosphorus in sediments of rivers flowing into Hongze Lake

The distribution and bioavailability of phosphorus (P) forms in 67 surface sediments of 7 rivers flowing into Hongze Lake were studied. The influencing factors and environmental significance of the spatial occurrence characteristics of phosphorus forms were discussed. The main content of organic phosphorus (Po) in the sediments of the Western area was the non active organic phosphorus (NLOP), which accounted for the relative contribution of Po 50.41% The relative contribution of biological available inorganic phosphorus (BAP) was the highest, accounting for 70.57%. In the southwest and Northwest area, the main source of Po was middle active organic phosphorus (MLOP), and the main source of Pi was calcium bound inorganic phosphorus (HCl-Pi). Due to the influence of local geological background, the relative content of HCl-Pi in the Northwest area was the highest (42.99%). So as to slow down the movement of phosphorus and minimize the pollution. With the increasing pollution degree of sediment, the concentration of bioavailability Po increased, but the relative contribution of Po decreased. The concentration of HCl-Pi increased, and the relative contribution of Pi decreased, which was universal in the lake sediments with different eutrophication degree in China. The western and southwest areas were mainly affected by soil erosion, non-point source pollution and algae growth. With the relatively higher organic matter environment, the organic phosphorus components that can be degraded by organic matter (OM) were higher than those that can be mineralized. Under the condition of relatively weak water exchange capacity, most of the organic phosphorus components which were difficult to degrade were easy to deposit, resulting in higher BAP concentration and eutrophication processed in the western and southwest areas high degree. There was a significant correlation between the forms of Pi and Po in the sediments. The results showed that the trace ability of all forms of phosphorus was consistent. Under certain conditions, the active Po can be converted into the BAP, while the unbioavailable Po could be converted into the BAP, which increased the ecological risk of the river sediments from Hongze Lake. It could be seen that OM was the key factor for the transformation of various forms of phosphorus, which was closely related to the biochemical cycle of endogenous phosphorus in sediments. The spatial difference of phosphorus forms in the sediment of Hongze Lake was mainly caused by the input of agricultural exogenous pollutants, which aggravated the internal phosphorus load. For the West and the southwestern of areas, the agricultural non-point source pollution should be mainly controlled, and the collection, discharge and treatment facilities of rural sewage pipe network should be accelerated. According to the characteristics of the river, the "no breeding area" and "restricted breeding area" should be defined.In order to reduce the soil and water loss of agricultural land, it was suggested to increase the exchange rate of water body by copper enclosed net cage, no tillage or shallow cross slope ridge cultivation, and to follow the principle of a few times of fertilization. For the northwest area of Hongze Lake, we should focus on the prevention of soil erosion caused by excessive urbanization and the excessive pollution load on the ecological function protection area.