State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Beijing Normal University, Beijing, 100875, China.
Environ Monit Assess. 2012 Apr;184(4):2237-45. doi: 10.1007/s10661-011-2113-8. Epub 2011 May 15.
The chemical forms and ecological risk of As were characterized in the sediment of the Daliao River System (DRS), which has been affected by long-term intensive industrial, urban, and agricultural activities. Twenty-seven samples of surface sediment were collected and analyzed for total As content and that of its chemical forms. The results indicated that the average total As content in the sediment was 9.83 mg kg(- 1) but that the levels ranged from 1.57 to 83.09 mg kg(- 1). At the sites near cities, mining sites, and the estuary of the DRS, it is likely that adverse effects on aquatic organisms occur, due to As levels in the sediment that are often higher than the threshold effect level and occasionally higher than the probable effect level. A selectively sequential extraction indicated that the majority of As in the sediment was bound to Fe oxides (62.1%), with moderate proportions of residual As (19.8%), specifically adsorbed As (17.9%), and a low proportion of non-specifically adsorbed As (1.1%). In addition, the content of Fe in the sediment was positively and significantly correlated with the contents of amorphous and crystalline Fe oxide-bound As, confirming the crucial role of Fe oxides in immobilizing high amounts of As in superficial environments. The average molar ratio of As to Fe was 1.18 × 10(- 4) in the surface sediment of the DRS, similar to that of natural Fe oxides, but much lower than that of synthesized Schwertmannite. Therefore, the release of As under reduced and low pH conditions can cause serious problems for water resources and for living organisms.
受长期密集的工业、城市和农业活动影响，大辽河流域（DRS）的沉积物中的砷的化学形态和生态风险特征已被描绘出来。采集了 27 个表层沉积物样品，并对其总砷含量及其化学形态进行了分析。结果表明，沉积物中总砷的平均含量为 9.83mgkg(-1)，但含量范围为 1.57-83.09mgkg(-1)。在靠近城市、矿区和 DRS 河口的地点，由于沉积物中砷的水平通常高于阈值效应水平，偶尔甚至高于可能的效应水平，因此可能对水生生物产生不利影响。选择性顺序提取表明，沉积物中大部分砷与铁氧化物结合（62.1%），中等比例的残余砷（19.8%）、特定吸附砷（17.9%）和低比例的非特定吸附砷（1.1%）。此外，沉积物中 Fe 的含量与无定形和结晶态铁氧化物结合态 As 的含量呈正显著相关，这证实了铁氧化物在固定表层环境中大量 As 方面的关键作用。大辽河流域表层沉积物中 As 与 Fe 的平均摩尔比为 1.18×10(-4)，与天然铁氧化物相似，但远低于合成 Schwertmannite 的摩尔比。因此，在还原和低 pH 条件下释放的 As 可能会对水资源和生物造成严重问题。
