武汉市后官湖水环境问题和污染防治对策分析

武汉市后官湖因流域城镇化迅速发展,水环境状况日渐恶化。首先对后官湖水质历史和现状分析,得出TP、TN和CODMn为主要超标因子。再结合流域土地利用现状、湖泊污染特征及其行政区划等,将后官湖流域划分成5个污染控制区(H1、H2、H3、H4和H5污染控制区),对各污染控制区中点源、面源污染进行分析,得出点源和农村生活为流域最重要污染源,两源共计排放CODMn、TN、TP和NH3-N占整个流域污染的82.9%,76%,78%和80.8%。污染控制区贡献量中,CODMn最大为H4(25.7%)和H3(23.97%);TN最大为H3(30.28%)和H4(25.31%);TP最大为H4(29.33%)和H2(25.62%);NH3-N最大为H3(31.77%)和H4(24.44%)。单位面积入湖强度中,H3区域CODMn、TN、TP和NH3-N强度最大,分别为35.57t/(a·km2),6.87t/(a·km2),0.85t/(a·km2)和5.57t/(a·km2),表现出污染强度"西低东高"的污染特征。针对上述污染特征本研究提出后官湖流域和各个分区污染防治对策,并对基于流域分区控制下污染物入湖量进行了测算。

WATER ENVIRONMENTAL PROBLEMS AND MANAGEMENT COUNTERMEASURES IN HOUGUANHU LAKE IN WUHAN

The water environment of Houguanhu Lake was gradually to be worse with the rapid development of urbanization in Wuhan.This study was first focused on the history and current status water quality of Houguanhu Lake,and found that total phosphorous (TP),total nitrogen (TN) and permanganate index (CODMn) were the main pollutants in Houguanhu Lake in these years.In order to find out the sources and contributions of the pollutions,the Houguanhu Lake basin was divided into 5 pollution control districts (PCDs) which named H1-West farmland & forest PCD,H2-North urban PCD,H3-Northeast urban & industry PCD,H4-Southwest farmland & forest PCD and H5-South urban PCD,on the basis of land use structure,characteristics pollution and administrative divisions.The point source pollutions and non-point source pollutions were analyzed comprehensively.Rural pollution and point source outfalls were the major pollution sources which were account for 82.9％ CODMn,76％ TN,78％TP and 80.8％ ammoniacal nitrogen (NH2-N) from the whole basin sources.From the analysis of contributions of pollutants from each PCD,the H3 PCD and the H4 PCD contributed the most CODMn,TN,TP and NH3-N to Houguanhu Lake.These two PCDs were accounted for 23.97％ and 25.70％,30.28％ and 25.31％％,25.62％ and 29.33％,31.77％ and 24.44％ of the total pollutants,successively and respectively.And also the H3 PCD was the largest contribution in per km2 in basin from all of the PCDs,with CODMn,TN,TP and NH3-N were 35.57 t/(a · km2),6.87 t/(a · km2),0.85 t/(a ·km2) and 5.57 t/(a · km2),respectively.In this study,we proposed several effective management countermeasures for each PCD and the whole basin,and evaluated the reduction of pollutants.