地下水中胶体对金属样品采样代表性的影响

Influence of Colloid in Groundwater on Sampling Representativeness of Metals Samples

地下水溶质迁移的相关研究表明,胶体行为对地下水溶质迁移起着至关重要的作用,而地下水的采样过程以及现场处理会造成胶体行为的改变,进而影响采集的地下水样品的代表性。文中选取无机金属元素作为代表性判断的指标,结果表明:随着胶体行为的改变,地下水中铝、铁、锰、钡等易吸附在胶体上的金属,含量发生变化,因此,胶体的存在使样品的均匀性变差,不能代表目标含水层的地下水组成;采用现场过滤可有效减小对胶体的影响,且应尽量选择对地下水水动力扰动较小的采样方式,如低流速气囊泵,能够有效避免胶体的形成,有效降低胶体的影响,提高地下水样品的代表性。

Relevant researches on groundwater solute migration show that colloidal behaviors play a vital role in groundwater solute migration,and groundwater sampling process and on-site treatment may cause changes in colloidal behavior,which may affect the representativeness of collected groundwater samples.In this paper,inorganic metal elements were selected as the representative index.Results showed that with the change of colloidal behavior,contents of metals easily adsorbed on colloids such as Al,Fe,Mn and Ba in groundwater were different.Therefore,the existence of colloid made the uniformity of sample worse and could not represent groundwater composition of target aquifer.The influence of colloids could be effectively removed by the use of in-situ filtration,and selection of sampling methods that had fewer disturbances to groundwater hydrodynamics,such as low-velocity air bag pumps,could effectively avoid the formation of colloids,effectively reduce the impact of colloids,and improve representativeness of groundwater samples.