江苏水源地型水库异味物质发生风险及影响因素

为认知水源地型水库异味发生风险及其规律,本研究于异味风险高危期(夏季),对江苏17个省级水源地型水库开展了水质、浮游生物和异味物质状况调查.结果表明,本次调查的17个水库普遍存在富营养化程度偏高(如藻类生物量偏大和水体透明度偏低)的问题,约三分之一的水库出现部分水层异味物质2-甲基异莰醇(MIB)浓度超标,MIB平均浓度为(13. 7±20. 7) ng·L-1,表明江苏省水库型水源地普遍存在MIB风险;多个水库检出土臭素(GSM),但其浓度均没有超过10ng·L-1的饮用水标准浓度(最大浓度为4. 6 ng·L-1);同步水质调查及统计分析表明,MIB浓度和水体叶绿素a浓度、水体透明度、悬浮颗粒物浓度、富营养化指数等重要水质指标及浮游植物生物量(特别是蓝藻生物量)相关性显著(P 0. 05),其中MIB与叶绿素a、富营养化指数呈极显著的相关关系(P 0. 01).因此,水源地型水库的异味物质风险与水库的富营养化密切相关;实施营养盐外源输入削减、提高流域植被覆盖度、科学调控渔业养殖规模等水体富营养化控制措施是水库异味物质控制的关键.

Occurrence and Influencing Factors of Odorous Compounds in Reservoirs Used as Drinking Water Resources in Jiangsu Province

In order to recognize the risk of odorous compounds and its driving mechanisms in water source reservoirs, the water quality, plankton, and odorous compounds of 17 provincial water source reservoirs in Jiangsu Province were investigated during a high-risk period of odorous compounds. A high eutrophication status, such as high algal biomass and low transparency, were widely observed in our study reservoirs. In addition, 2-methylisoborneol (MIB) exceeded the standard in some water layers of one-third of the reservoirs, of which the average concentration was (13.7±20.7) ng·L^-1. Geosmin (GSM) was also detected in several reservoirs, although the maximum concentration of 4.6 ng·L^-1 did not exceed the drinking water quality standard. With respect to the relationships between odorous compounds and environmental conditions, significant correlation (P<0.05) was noted between the MIB concentration and eutrophication indicators, including chlorophyll-a, Secchi depth, suspended solids, and comprehensive nutrition state index (TLI), particularly for chlorophyll-a and TLI (P<0.01). These results indicate that the risk of odorous compounds in water source reservoirs depend largely on the eutrophic status. Therefore, nutrient reduction, improvement in vegetation coverage of the reservoir basin, reasonable fishing practices are considered as effective strategies to avoid the risk of the odorous compounds in reservoirs.