太湖西岸宜兴城市水系污染物时空分布特征

Characteristic of spatial-temporal distribution of urban water pollutants of Yixing city located in the west shore of Taihu Lake

选用2011—2014年宜兴市12个监测断面21个水质指标的连续监测数据,解析太湖西岸宜兴城市水系污染物的时空分异特征及影响因素。结果表明,宜兴市城区及入太湖河流污染严重,86.05%以上时段内处于劣Ⅴ类水平,特征污染物为TN、NH3-N、BOD5、TP、COD和Hg。污染物空间分异程度大小依次为:AR-OH>NH3-N>Hg>TP>COD>BOD5>F->oil=CODMn>LAS>TN>DO。不同区域河流污染物浓度随时间变化基本一致,有机物夏季波动较大主要受温度和降雨的双重影响,TN和NH3-N浓度标线出明显的季节变化:春季>冬季>夏季>秋季,Hg、LAS、AR-OH表现出瞬时排放特性,且主要发生在年初。由分析可得,土地利用强度和方式是影响宜兴市城区及入湖河流污染物分布特征的最主要因素,其次是污染来源、河道类型等的影响,表现为城市核心区、三氿入湖区和西北入湖区污染程度依次增大,但差异水平不明显,西南入湖区则相对较轻。

The continuous monitoring data for 21 water quality parameters from 12 monitoring sections during2011 to 2014 were collected to analyze the characteristics of spatial-temporal distribution and the effect of water pollutants from the city of Yixing,which is located on the west bank of Taihu Lake. The results showed that the urban stream and Taihu Lake were highly polluted. The water quality was lower than the class V standard（ i. e.,86. 05%）.The main pollutants were TN,NH3-N,BOD5,TP,COD,and Hg. The successive spatial variation of the pollutants was as follows： AR-OH〉 NH3-N〉 Hg〉 TP〉 COD〉 BOD5〉 F- 〉oil = CODMn 〉LAS 〉TN〉 DO. The variations in pollutant concentrations in the rivers were consistent over time in different areas. Because of temperature and rainfall variations,the concentration of organic matter fluctuated during summer. In addition,the concentrations of TN and NH3-N varied with seasonal changes as follows： autumn 〉winter〉 summer 〉autumn. Hg,LAS,and AR-OH were discharged instantaneously at the beginning of the year. As a result,the intensity and method of land use was the main factor affecting pollutant distribution in Yixing. Other factors such as pollutant source and river type also impacted the pollutant distribution,which increased in the urban core,the lake area of Sanjiu district,and the lake area of the northwest in sequence,while the difference was not obvious. In contrast,the lake area in the southwest was less polluted.