济南市玉符河多水源回灌岩溶水水质风险评价

Assessment of water quality risk from karst aquifer recharge with multi-source water in the Yufuhe river,Ji'nan

济南以泉城而闻名,保泉和供水安全问题是其面临的巨大挑战,利用多水源进行岩溶水回灌是解决问题的有效措施之一,但是补给水源水质相对岩溶水而言较差,回灌到地下可能存在一定健康和环境风险,需要对回灌系统的水质进行风险评价。本文对比地下水质量标准和地下水水质背景值,重点选择地表源水超标和劣于背景值的风险源监测指标,借鉴澳大利亚含水层补给管理指南,对玉符河多水源回灌岩溶含水层工程运行期的水质风险进行评价。2015年对黄河水、卧虎山水库两种水源多次回灌期间的源水、孔隙水和岩溶水的22项指标进行水质监测和指标分析,风险残余评价结果表明黄河水回灌补源期间,平均浊度的标准指数源水是1.4,孔隙水1.7,岩溶水0.93,硫酸盐平均含量的标准指数源水是0.93,孔隙水0.9,岩溶水0.73,氯离子虽没有超过地下水Ⅲ类标准,但是在源水中含量是地下水含量的2倍多;卧虎山水库水回灌补源期间,平均浊度的标准指数源水是2.4,孔隙水1.1,岩溶水0.43,硫酸盐平均含量的标准指数在源水0.75,孔隙水0.84,岩溶水0.66,氨氮的平均含量的标准指数源水1.14,孔隙水1.47,岩溶水1.35。因此,浊度、硫酸盐和溶质在裂隙岩溶含水层迁移较快为两种水源玉符河回灌补源工程的共同高风险项和关键控制点。此外,黄河水补源还需注意盐度,卧虎山水库水补源还需控制营养物的污染风险。基于以上评价,还提出了限制回灌量占区域岩溶水资源量比例等建议。

Ji'nan is well known for Spring City,while facing huge challenges of spring protection and security of water supply.The aquifer recharge with multi-source water is one of the effective measures to solve these problems.However,the quality of source water is still poorer than karst water,which would caused some risk of health and safety.Comparing the standard of groundwater quality and the background value of karst water quality,this work chose the risk monitoring indicators that exceed the standard in surface water sources or are inferior to background values.And adopting the Australian Guidelines of MAR,we assessed the water quality risk of the aquifer recharge with multi-source water in the Yufuhe river.In 2015,monitoring and index analysis were performed to the water quality of source water,pore well water and karst deep well water when Yellow River water and Wohushan reservoir water recharging the aquifers many times.The results show during the Yellow River water recharging,respectively in source water,pore water and karst water,the standard indexes of average turbidity are 1.4,1.7 and 0.93,the standard indexes of sulfate's average content are 0.93,0.9 and 0.73 and although the content of chloride ion does not exceed the groundwater class Ⅲ standard,it in the source water content is more than 2 times the groundwater content;during the Wohushan reservoir water recharging,respectively in source water,pore water and karst water,the standard indexes of average turbidity are 2.4,1.1 and 0.43,the standard indexes of sulfate's average content are 0.75,0.84 and 0.66 and the standard indexes of ammonia nitrogen's average content are 1.14,1.47 and 1.35.We draw conclusion that the turbidity,sulfate and the movement of pollutants in the aquifers are at critical points for the whole Yufuhe aquifer recharge project.In addition,the risk of salinity should receive attention when the Yellow River water is used as the recharge source.Similarly,the risk of nutrient is also a concerned issue when the Wohushan reservoir water is the recharge source.Based on the above analyses,this paper offers some suggestions,such as limiting the proportion of karst water resources.