【作者】 罗锡明；

【导师】 钟佐燊； 汤鸣皋；

【作者基本信息】 中国地质大学（北京） ， 环境工程， 2007， 博士

【摘要】 金矿的伴生矿主要是含砷矿物,金矿开采引起的砷的环境污染已是不争的事实,水环境是砷产生和释放毒害效应的一个重要介质和途径。不同价态的砷,其毒性也不一样。通常,无机砷化合物比有机砷化合物的毒性大,As(III)类比As(V)类的毒性大约50倍。因此,对水环境中不同形态的砷进行研究是环境评价的重要内容。针对含砷金矿床的开采引发的砷污染的问题,本论文以辽宁丹东地区杨树金矿为研究对象,在枯水期和丰水期进行矿区河流和地下水的取样调查研究,并在室内进行静态吸附实验和土柱吸附实验研究水环境中不同形态的砷在浅层含水系统的迁移规律及土壤对砷的吸附容量,结合实测数据预测砷在河流的迁移规律。本文首先利用离子色谱--氢化物发生—原子荧光(IC-HG-AFS)联用方法研究了不同形态砷的分析方法,该方法具有成本低,灵敏度高,As(Ⅲ)、As(Ⅴ)、一甲基砷(MMA)、二甲基砷(DMA)最小检出量分别可达2.0μg /L、4μg /L、4μg /L和4μg /L,相对标准偏差(n=7)小于5%。同时进行了水样保存实验研究,水样首先通过0.45μm滤膜并在4℃下低温保存,可有效地降低微生物对不同形态砷化合物相互转化的影响。在水样中加入酸,把水样酸化到pH≤2或是加入EDTA,可有效地降低Fe、Mn等金属氢氧化物沉淀产生,以防止其对砷的吸附。其次,本文通过野外枯水期和丰水期的野外水样调查,发现金矿开采对周围的水环境会造成砷的污染,超出国家GB3838-2002地表水水质III类标准的3～20倍,地表水和地下水中都没有发现有机胂,只有三价砷和五价砷。砷在枯水期较丰水期难以迁移,通过计算得到,在枯水期砷的衰减系数K值为0.3082(1/km),而在丰水期为0.0569(1/km);在污染口浓度达到500μg/L时,下游没有其它的砷的污染源(或会影响砷衰减的其它污染源)时,枯水期砷会在下游7.5km之后浓度降到50μg/L,而丰水期则要在下游40km之后才能降到同样的值,所以在丰水期砷污染的影响的流域更广。金矿区的河流中砷主要是以五价砷为主,枯水期占90%以上,丰水其占78%以上,没有发现有机胂。潜水含水层的土壤砂样对砷有强烈吸附作用,土壤砂样对五价砷的吸附能力大于三价砷的吸附能力,通过D-R(Dubinin-Radushkevich)方程,我们得到六种配水中土壤砂样对砷的吸附量。三价砷进入实验柱后很快转化成五价砷;在柱子不同的距离,砷的零延迟时间随着距离的增大而增长,砷在土壤砂样中是一次性吸附;其吸附动力学符合零级反应动力学方程。更多还原

【Abstract】 Mineral bearing arsenic is commonly found in gold mine. Contamination caused by golden mining has been studied for several decades. Water is one of the main mediums and paths for arsenic to produce and release toxic effect on human. The toxicity of arsenic depends on its different species, generally speaking, inorganic states are more toxic than organic species. For inorganic species, As (III) is 50 times toxic than As(V). So researchers are very interested in As species in order to assess the environment quality or toxicity.For the contamination from golden mining, this study takes Yangshu Gold Mine as research area. It’s located in Dandong, Liaoning province. In this paper, samples from surface water and groundwater were collected in both dry and wet season. The author conducted batch and column experiments in laboratory for studying the transport and adsorption capacity of different species arsenic, and forecast transport rules of arsenic in surface water.Firstly, the method of different species arsenic was studied by IC-HG-AFS(ion chromatography-hydrogen generation-atom fluorescence spectrometer). The detection limits of As(Ⅲ), As(Ⅴ), mono-methyl arsenic (MMA) and di-methyl arsenic (DMA) could be lowed 2.0μg /L,4μg /L,4μg /L and 4μg /L respectively. The relative standard deviation(RSD) of determination(n=7) was less 5%. At the mean time, the preservation experiment was done. The experiment data showed transform between As(Ⅲ) and As(Ⅴ) was effectively reduced when samples filtered by 0.45μm membrane were stored at 4℃because filtration and cold storage reduced amount and activity of microbe. Sorption of arsenic caused by Fe and Mn precipitation was cut down by adding EDTA or acid that makes pH≤2.Secondly,based on field survey in dry and wet season, Arsenic in aquatic environment comes from gold mining. The concentration of total arsenic is 3-20 times over surface water quality standard(Ⅲ). Arsenate and arsenite were found in surface water and groundwater, but no organic arsenic was identified.Compared to wet season, arsenic is difficult to mobile in dry season. Attenuation constant in dry season is 0.3082(1/km), but it is 0.0569(1/km)in wet season. If initial concentration of As was 500μg/L without other contamination source in down stream, arsenic would deceased to 50μg/L in down stream 7.5km in dry season but 40km in down stream 40km. As(Ⅴ) is dominate species in river running throμgh mining area. 90% of total arsenic is As(Ⅴ) in dry season, 78% in wet season. There were not any organic arsenic was found.Arsenic can be adsorped by sand medium form shallow aquifer which has stronger sorption for As(Ⅴ) than As(Ⅲ). Based on D-R(Dubinin-Radushkevich) equation, adsorption energy of 6 kinds of simulated water were obtained by batch eaperiments. As (Ⅲ) was oxidized to As(Ⅴ) quickly in column experiments. Adsorption of As on sand finished instantaneously and zero detention time rose with mobility distance. The sorption kinetic of arsenic on aquifer medium fits zero-order dynamics equation.更多还原