太湖流域池塘养殖污染排放估算及其空间分布特征

Estimates and characteristics of pollutant discharge from pond cultures in the Taihu Basin

池塘养殖是农业源污染的重要来源之一,尤其在水网密布、渔业发达的太湖流域,控制池塘养殖过程中氮、磷、化学需氧量等污染物的排放,对于减轻水体富营养化程度、恢复水质健康、维持地区社会经济可持续发展具有重要意义.基于野外采样、入户调查、遥感解译等多种手段,结合GIS软件技术,对太湖流域池塘养殖污染物的排放进行了估算.结果表明,20142015年太湖流域总氮、硝态氮、铵态氮、总磷、可溶性磷、COD Cr的年排放量分别为6.1×10^6、1.1×10^6、1.7×10^6、1.3×10^5、1.1×10^5和8.0×10^7 kg.其中鱼类池塘养殖排放系数分别为69.5、12.4、20.1、1.6、1.3和919.8 kg/hm 2;虾类池塘排放系数分别为3.0、0.5、0.9、0.07、0.06和39.3 kg/hm^2;蟹类池塘排放系数分别为6.4、1.2、1.9、0.2、0.1和84.9 kg/hm^2.太湖流域池塘养殖各类污染物排放分布特征为位于太湖西北部、南部和东北部的大部分地区池塘养殖污染物排放较高,位于太湖东部和太湖西南部的池塘养殖污染物排放较低.池塘养殖业发达、饲料肥料投入高、养殖密度大等是造成该流域池塘养殖污染物排放较高的主要原因.针对太湖流域池塘养殖减排治理,建议推行合理的池塘污染治理管理政策与策略,综合考虑饲料利用率与投放量、养殖面积、养殖密度、养殖生物生态混养,以及一些科学养殖管理措施和净化养殖废水的技术措施等.

Pond culture,as a major component of aquaculture,is one of the important sources of agricultural source pollution.Pollutions from pond culture has been a big threat in the Taihu Basin,where with dense water network and developed fisheries.Hence,to reduce the eutrophication of water bodies,and to restore water quality and health,it is important to control the discharges of nitrogen,phosphorus,chemical oxygen demand and other pollution sources during pond culture.Based on field sampling survey and remote sensing interpretation,this study combined with GIS software to estimate the pollution load of pond culture in the Taihu Basin.The results showed that discharges of total nitrogen(TN),nitrate nitrogen(NO-3-N),ammonium nitrogen(NH+4-N),total phosphorus(TP),dissoluble phosphorus(DP)and chemical oxygen demand(COD Cr)in the Taihu Basin during 2014-2015 were 6.1×10^6,1.1×10^6,1.7×10^6,1.3×10^5,1.1×10^5 and 8.0×10^7 kg,respectively.The discharge factor of the above pollutions for fish ponds were 69.5,12.4,20.1,1.6,1.3 and 919.8 kg/ha,shrimp ponds were 3.0,0.5,0.9,0.07,0.06 and 39.3 kg/ha and crab ponds were 6.4,1.2,1.9,0.2,0.1 and 84.9 kg/ha.All of the pollutions from fish pond culture were much higher than those of shrimp and crab pond culture.The distribution characteristics of various pollution sources in pond culture in this basin were similar.The pollution discharge in the northwest,south and northeast of the Lake Taihu was higher in most areas than those in the east and southwest of it.Factors such as the well-developed pond farming industry and high fertilizer input result in high pollution discharge from ponds in this basin.Therefore,we proposed some reduction measures to control pond culture pollution in this basin,these could also be referenced by other basins.