北京密云水库流域1980～2003年地表水质评价

对密云水库所处流域的4个监测点1980～2003年的地表水质数据进行分析,并参考单因子水质标识指数方法以国家地表水环境质量标准为标准进行地表水质评价.结果表明,4个监测点上都是TP的年际波动最大,变异系数分别为93.86%、86.08%、50.56%和139.47%;其次是Hg,4个监测点的变异系数分别为86.08%、25.75%、56.52%和47.01%;其余5个指标的变异系数相对较小.流域内4个监测点的高锰酸盐指数、BOD5、Pb和Cr都未超过饮用水标准限值;Hg只是在个别年份上(S1和S3在1992年,S4在1996年)超过饮用水标准限值.该流域主要是以TN和TP的污染为主,而且大部分年份TN比TP的污染严重.与1990年前十年平均水平相比,流域内1990年后十年平均化肥、农药和农用薄膜使用量分别增加了46%、1.73倍和3.59倍.畜牧业产值比重从1990年前的24.4%增加到1990年后的39.8%.与1990年前十年平均水平相比,1990年后十年平均工业总产值增长了4.24倍.空间上的分析表明,密云水库上游的污染风险大于下游出口的污染风险,而且潮河流域TN和TP污染物质对库区TN和TP污染发生的贡献大于白河流域.

Surface Water Quality Assessment in Miyun Reservoir Watershed, Beijing in the Period 1980-2003

Single factor water quality identification index was adopted to assess the surface water quality of Miyun reservoir watershed in Beijng using nearly 20 years monitoring data of 4 sites, also the surface water quality pollution sources were analyzed. The results indicated TP had the largest temporal variation at every monitoring site, coefficients of variation were 93.86%, 86.08%, 50.56% and 139.47%, respectively. The following element was Hg, the coefficients of its variation were 86.08%, 25.75%, 56.52% and 47.01%, respectively. While TN, permanganate index, BOD₅, Pb and Cr were relatively stable with small coefficient of temporal variation. The permanganate index, BOD₅, Pb and Cr did not exceed to the Chinese surface drinking water standard limit in the study period, while Hg had high pollution risk in several years, such as monitoring sites S1 and S3 in 1992, monitoring sites S4 in 1996.The major pollutants of Miyun reservoir watershed in Beijing were TN and TP, and TN had larger pollution risk compared with TP in most years. Comparing to that before the 1990s, the decade average fertilizer, pesticide and agricultural plastic mulch inputs after the 1990s had increased by 46%, 173% and 359%, respectively. The husbandry proportion in agriculture rose from 24.4% to 39.8%, and the average gross industrial production by 424%. The upstream of Miyun reservoir had larger pollution risk than its downstream. In addition, Chaohe watershed contributed more TN and TP to the reservoir than Baihe watershed.