降雨条件下岩溶泉水中悬浮颗粒物的运移特征及来源分析

Transportation and Sources of the Suspended Particle in a Karst Spring During a Storm Event

降雨期是揭示岩溶地下水系统物质能量输入和输出的重要阶段.以重庆青木关地下河系统的出口姜家泉为例,监测了降雨条件下泉水中不同粒径悬浮颗粒物分布,辅助以水文地球化学手段,对岩溶地下水悬浮颗粒物的运移特征和来源进行了探讨.结果表明,在降雨初期,由于外源物质的输入,泉口渠道地表水中0～11μm悬浮颗粒物的数量急剧升高;而后当地下水主要靠岩溶裂隙水补给时,泉水中0～11μm悬浮颗粒物的数量升高,再悬浮作用占到主导地位;继而雨水补给整个流域地下水系统,稀释作用占主导地位时,泉水中0～4μm悬浮颗粒物的数量升高,地下水悬浮颗粒物为外源物质.由于研究区特定的水文地质条件和降雨强度,悬浮颗粒物的临界粒径为4μm,对于泉水是否受到微生物的污染可能有着重要的指示意义.

Storm periods are the crucial stage to reveal input and outlet of material and energy in groundwater system.Jiangjia spring,the outlet of Qingmuguan groundwater system,was taken as an example.Distribution of suspended particle in the Jiangjia spring was continuously monitored.Supported by hydrochemical data,characteristics and sources of the suspended particle in the karst groundwater system were investigated.Results show that the number of suspended particle in size of 0-11 μm abruptly increased in the channel of Jiangjia spring at the beginning of rainfall occurred.It indicates the suspended particle was derived from allochthonous material.While the groundwater was recharged by karst fissure,the number of suspended particle in size of 0-11 μm sharply raised,which shows that the suspended particle was autochthonous.Finally,the number of suspended particle in size of 0-4 μm elevated due to the entire groundwater watershed recharged by rainfall and dilution effect occurring again,suggesting the suspended particle was derived from allochthonous material.Owing to the intrinsic hydrogeological settings and rainfall intensity,the threshold of size for the suspended particle was 4 μm in Qingmuguan groundwater system.It probably was a high practical significance to indicate the groundwater was whether polluted by microbe or not.