Contamination from Sand‐Bentonite Seal in Monitoring Wells Installed in Aquitards
Contamination from Sand‐Bentonite Seal in Monitoring Wells Installed in Aquitards
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弱水层中安装的监测井中砂膨润土密封的污染
DOI：
10.1111/j.1745-6584.1997.tb00058.x
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
G. Kamp
中科院分区：
文献类型：
--
作者：
V. H. Remenda;G. Kamp
一项为期六年的现场实验表明，用于密封弱透水层中监测威尔斯井的砂-膨润土混合物向从这些威尔斯井中取样的地下水提供溶质。监测威尔斯安装在现场，水力传导率（K）范围为5 × 10 - 9 m/s至3 × 1011 m/s。在大多数情况下，钻孔在安装过程中保持干燥，从而可以放置带有溴化钾（KBr）标记的干粉膨润土/沙子混合物，以密封和分离采样点。在六年的时间里，定期对威尔斯井进行采样，并对地下水样本进行溴和氯以及其他主要离子的分析。与密封材料中约75 mg/l的估计初始浓度相比，前700天的典型Br结果范围为10 mg/l至35 mg/l。六年后，溴浓度降至3毫克/升至5毫克/升。在六年内去除的溴的总质量小于放置的溴的50%;因此，污染的影响，虽然大大减少，但仍然存在。Br、Cl、Na和SO 4的趋势表明发生了不同程度的污染。这些数据表明，用于密封弱透水层中监测威尔斯井的材料可能对威尔斯井中的水的化学性质产生显著且持久的影响。
A six year field experiment has shown that a sand‐bentonite mixture used to seal monitoring wells in aquitards contributes solutes to the ground water sampled from these wells. Monitoring wells were installed at field sites with hydraulic conductivity (K) ranging from 5 × 10 ‐9 m/s to 3 × 1011 m/s. In most cases the boreholes remained dry during installation which allowed the placement of a dry powdered bentonite/sand mixture tagged with potassium bromide (KBr) to seal and separate sampling points. Over six years, wells were sampled periodically and ground‐water samples were analyzed for Br and Cl and other major ions. Typical Br results ranged from 10 mg/1 to 35 mg/1 in the first 700 days, as compared to an estimated initial concentration in the seal material of about 75 mg/1. After six years the bromide concentrations had decreased to between 3 mg/1 and 5 mg/1. The total mass of Br removed in six years is less than 50% of that placed; therefore the contamination effects, although considerably diminished, persist. The trends of Br, Cl, Na, and SO4 indicate that varying degrees of contamination occur. These data show that the materials used to seal monitoring wells in aquitards can have a significant and long‐lasting impact on the chemistry of the water in the wells.