Impact of Pressure on Arsenic Released from Pore Water in Clayey Sediment.
Impact of Pressure on Arsenic Released from Pore Water in Clayey Sediment.
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压力对粘土沉积物孔隙水中砷释放的影响
DOI：
10.3390/toxics10120738
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发表时间：
2022-11-29
期刊：
影响因子：
4.6
通讯作者：
中科院分区：
文献类型：
--
作者：
过量抽水会导致砷从粘土含水层中的孔隙水中释放到含水层中。地下水开采过程中的抽水量可能会随着时间的推移而变化，从而导致不同的土壤压实率或模式。然而，人们对粘土含水层压实过程中压力对砷释放的影响知之甚少。我们利用粘土沉积物进行了实验室压实实验，通过分析压实实验不同阶段采集的孔隙水样中存在的化学特征和砷的形态，确定了压实速度和模式对砷释放的影响。根据压实度的不同，土壤水分释放呈现快速(PV线性增大)和缓慢(PV指数增大)的特征。我们观察到慢型的砷浓度(6.7~36.4μg/L)明显高于快型(7.6~16.1μg/L)。此外，加速压实模式的浓度最高(16.8~47.4μg/L)，其次是恒速压实模式和减速压实模式(4.3~14.4μg/L)。总体而言，压实速度和压实模式没有改变砷的释放机制，但它们确实改变了每个阶段沉积物的水分含量，从而间接导致了释放的砷浓度的差异。这些结果表明，必须考虑抽水率和抽水模式，以防止地下水开采方案中的砷污染。
Overpumping can cause arsenic to be released from the pore water in clayey aquitards into aquifers. The amount of water pumped during groundwater exploitation may change over time, leading to different soil-compaction rates or patterns. However, the impact of pressure on the release of arsenic during the compaction of a clayey aquitard is poorly understood. We performed a laboratory-compaction experiment using clayey sediment to identify the effects of compaction rates and patterns on arsenic release by analyzing the chemical characteristics and arsenic species present in pore water samples collected at different stages of the compaction experiment. A rapid (PV increased linearly) and a slow (PV increased exponentially) water-release patterns were recognized according to the compaction rate. We observed that arsenic concentrations in the slow pattern (6.7 to 36.4 μg/L) were considerably higher than those in the rapid pattern (7.6 to 16.1 μg/L). Furthermore, concentrations were the highest in the accelerated compaction pattern (16.8 to 47.4 μg/L), followed by those in the constant and decelerated patterns (4.3 to 14.4 μg/L). Overall, compaction rate and pattern did not alter the arsenic-release mechanism; however, they did alter the moisture content of the sediment at each stage, which indirectly led to differences in the released arsenic concentrations. These results suggest that pumping rates and patterns must be considered to prevent arsenic contamination in groundwater-extraction scenarios.
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