Institute of Soil and Environmental Sciences, University of Agriculture Faisalabad, Faisalabad, 38040, Pakistan; Department of Environmental Sciences and Engineering, Government College University Faisalabad, Faisalabad, 38000, Pakistan.
Institute of Soil and Environmental Sciences, University of Agriculture Faisalabad, Faisalabad, 38040, Pakistan; MARUM and Department of Geosciences, University of Bremen, Bremen, D-28359, Germany.
Chemosphere. 2018 May;199:737-746. doi: 10.1016/j.chemosphere.2018.02.002. Epub 2018 Feb 3.
In this study, we tested 123 groundwater wells from five different areas of Punjab, Pakistan for arsenic (As) contamination level and species, as well as delineated hydrogeochemical behaviour of As in aquifers. Results revealed that 75% and 41% of the groundwater wells exceeded the safe As limit of World Health Organisation (WHO, 10 μg L) and Pakistan-EPA (50 μg L), respectively. Arsenite (As(III)) and arsenate (As(V)) spanned 0-80% and 20-100% of total As (1.2-206 μg L), respectively. The mean As content (5.2 μg L) of shallow wells at 9-40 m depth did not exceed the WHO safe limit, representing a safe aquifer zone for pumping of groundwater compared to deeper wells at 41-90 m (51 μg L) and >90 m (23 μg L) depths. Piper-plot elucidated that the aqueous chemistry was dominated with Na-SO, Na-Ca-SO, Na-Mg-SO type saline water. Principal component analysis grouped As concentration with well depth, pH, salinity, Fe and CO, exhibiting that these hydrogeochemical factors could have potential role in controlling As release/sequestration into the aquifers of study area. Geochemical modeling showed positive saturation indices only for iron (Fe) oxide-phases, indicating Fe oxides as the major carriers of As. Overall, this study provides insights to tackle emerging As threat to the communities in Punjab, Pakistan, as well as help develop suitable management/mitigation strategies - based on the baseline knowledge of As levels/species and factors governing As contamination in the study area.
在这项研究中，我们测试了来自巴基斯坦旁遮普省五个不同地区的 123 口地下水井，以确定砷（As）的污染水平和种类，并描绘了含水层中 As 的水文地球化学行为。结果表明，75%和 41%的地下水井分别超过了世界卫生组织（WHO，10μg/L）和巴基斯坦环境保护局（EPA，50μg/L）的安全砷限值。亚砷酸盐（As(III)）和砷酸盐（As(V)）分别占总砷（1.2-206μg/L）的 0-80%和 20-100%。9-40m 深度的浅层水井的平均砷含量（5.2μg/L）未超过 WHO 的安全限值，与 41-90m（51μg/L）和>90m（23μg/L）深度的深层水井相比，这代表了一个安全的地下水抽取含水层。Piper 图表明，水化学主要由 Na-SO、Na-Ca-SO、Na-Mg-SO 型盐水组成。主成分分析将 As 浓度与井深、pH 值、盐度、Fe 和 CO 分组，表明这些水文地球化学因素可能在控制研究区含水层中 As 的释放/固定方面发挥了潜在作用。地球化学模拟显示仅铁（Fe）氧化物相呈正饱和指数，表明 Fe 氧化物是 As 的主要载体。总的来说，这项研究为解决巴基斯坦旁遮普省社区面临的新兴 As 威胁提供了深入了解，并有助于根据研究区 As 水平/种类和控制 As 污染的因素制定合适的管理/缓解策略。
