Department of Environmental Sciences, University of Peshawar, Peshawar, Pakistan.
Environ Monit Assess. 2018 Oct 18;190(11):649. doi: 10.1007/s10661-018-7043-2.
From health and environmental point of views, dioxins are important due to their toxicity and persistence. Dioxins have the potential to reside in the environment for longer time if sorbed onto the clay and organic content of the soil matrix. Their transport or leaching under certain environmental conditions such as preferential flow can increase the risk of groundwater contamination. In the current study, breakthrough curves (BTCs) against time were plotted for selected dioxin transport prediction; based on measured distribution coefficient (K), dispersion coefficient (D), and retardation factor (R). Three representative soil series named Burhan, Warsak, and Kunda were selected. For dibenzo-p-dioxin (DD), K values followed the order as: Burhan> Warsak > Kunda, while for 2-chloro dibenzo-p-dioxin (2 Cl-DD), K values followed an order as: Kunda > Burhan > Warsak. Dioxin transport was measured at two different linear velocities (20 and 50 cm day). Attainment of equilibrium was verified to be dependent upon the K, R, D, and chlorination on dioxin. Kunda series with low OM (0.6%), clay (0.2%), and R (377) was found to have relatively high DD transport potential under normal velocity, due to high dispersion values for its sandy nature. Under the steady or preferential flow conditions, all the plots obtained were identical irrespective of soil type and dioxin nature.
从健康和环境角度来看，二恶英因其毒性和持久性而非常重要。如果二恶英被土壤中的粘土和有机物质吸附，它们有可能在环境中存在更长时间。在某些环境条件下，如优先流，它们的迁移或浸出会增加地下水污染的风险。在本研究中，针对选定的二恶英迁移预测绘制了随时间变化的突破曲线（BTC）；基于测量的分配系数（K）、弥散系数（D）和迟滞因子（R）。选择了三个代表性的土壤系列，分别命名为布尔汗、瓦尔萨克和昆达。对于二苯并对二恶英（DD），K 值的顺序为：布尔汗>瓦尔萨克 > 昆达，而对于 2-氯二苯并对二恶英（2 Cl-DD），K 值的顺序为：昆达 > 布尔汗 > 瓦尔萨克。在两个不同的线性速度（20 和 50 cm 天）下测量了二恶英的迁移。发现平衡的实现取决于二恶英的 K、R、D 和氯化程度。由于其沙质性质，具有低 OM（0.6%）、粘土（0.2%）和 R（377）的昆达系列在正常速度下具有相对较高的 DD 迁移潜力。在稳定或优先流动条件下，无论土壤类型和二恶英性质如何，获得的所有图谱都是相同的。
