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金矿的开采和冶炼过程会对矿区河流产生严重的重金属污染。对采集的山东省招远界河受酸性矿山废水污染河道的表层沉积样品,采用BCR连续提取法分析了砷的赋存形态;采用搅拌式直流反应器(stirred-flow reactor)进行模拟淋洗实验,研究了沉积物中砷的动力学释放过程。结果表明:沉积物存在严重的砷污染,总砷的含量在778~3 389 mg/kg之间。其中弱酸可提取态、可还原态、可氧化态和残渣态含量分别占2.6%~9.8%,18%~79%,2.4%~7.1%,8.7%~75%,赋存形态分布主要受铁锰氧化物含量、有机质含量和p H等地球化学性质控制。在0.01 mol/L的Ca(NO_3)_2溶液淋洗420 min后,4种沉积物中砷的总释放量在8.3~99.7 mg/kg之间,占总砷含量的0.9%~3.7%。砷释放的最高浓度为29.7~468μg/L,与总砷含量趋势一致。砷的淋出浓度随着淋洗时间的延长逐渐降低,淋洗过程前200 min砷浓度的降低比较明显。分别在90 min和270 min设置了2次间歇,过后淋出液中砷浓度明显升高。可以看出,砷的释放是一个受时间控制的动力学过程,释放速率取决于沉积物的表面性质和砷的赋存形态。
The mining and smelting process of gold mines will cause serious heavy metal pollution to the mined rivers. The surface sediment samples collected from the rivers in Zhaoyuanjie River, Shandong Province, which were contaminated by acid mine wastewater, were analyzed by BCR continuous extraction method. The simulated leaching experiment was carried out with a stirred-flow reactor, The kinetic release of arsenic in sediments was studied. The results showed that there was serious arsenic pollution in the sediments, with total arsenic content between 778 and 3889 mg / kg. Among them, the content of weak acid extractable, reducible, oxidizable and residue accounted for 2.6% ~ 9.8%, 18% ~ 79%, 2.4% ~ 7.1%, 8.7% ~ 75% Manganese oxide content, organic matter content and p H geochemical properties. After the leaching of 0.01 mol / L Ca (NO 3) 2 for 420 min, the total arsenic release of the four sediments was between 8.3 and 99.7 mg / kg, accounting for 0.9% to 3.7% of the total arsenic content. The highest concentration of arsenic released was 29.7 ~ 468μg / L, which was consistent with the trend of total arsenic content. The arsenic leaching concentration gradually decreases with the leaching time, and the reduction of arsenic concentration is obvious 200 min before the leaching process. Two intermittent intervals were set at 90 min and 270 min, respectively, after which the arsenite concentration in the effusion increased significantly. It can be seen that the release of arsenic is a time-controlled kinetic process, the rate of release depends on the surface properties of sediment and the occurrence of arsenic.