高氯酸盐自然衰减的柱实验研究

Natural attenuation of perchlorate: A column experiment study

高氯酸盐(ClO_(4)^(-))是一种小分子量、有毒的无机络阴离子,普遍存在于环境中。由于其分子大小与碘离子相似,会干扰人体甲状腺的正常功能,因此其环境污染问题引起了广泛的关注。本文选取污染场地的天然河沙为试验材料,主要通过柱实验对地下水中ClO_(4)^(-)自然衰减过程进行研究,考察了铁氧化物、NO_(3)^(-)对ClO_(4)^(-)自然衰减过程产生的影响。结果表明,高氯酸盐自然衰减过程主要由微生物驱动,天然河沙可去除2 mg/L的ClO_(4)^(-),但其过程缓慢且还原量有限,长期去除率不超过10%,其限制因素为缺乏电子供体;铁氧化物可以促进ClO_(4)^(-)自然衰减,但当溶解性铁的浓度低于5.5 mg/L时,衰减过程开始受到影响;地下水中的NO_(3)^(-)会抑制ClO_(4)^(-)的降解,当NO_(3)^(-)低至10 mg/L或以下时,ClO_(4)^(-)才开始明显降解。

Perchlorate(ClO_(4)^(-)),a low molecular weight toxic inorganic complex anion is a widespread contaminant in the environment.Perchlorate contamination is a serious environmental problem as perchlorate is known to impact thyroid function by replacing iodine intake due to its similar molecular size with iodine.Column experiments,using river sand from the polluted site as the experimental material,were conducted to stimulate natural attenuation of the target pollutant,perchlorate(ClO_(4)^(-)).The effects of iron oxides and nitrate(NO_(3)^(-))were also evaluated.The results show that ClO_(4)^(-) natural attenuation is mainly dependent on microbial degradation in the aquifer,and the groundwater environment is more conducive to microbial activity.Natural river sand can remove 2 mg/L ClO_(4)^(-);however,the process is slow and the reduction amount is limited.A lack of electron donors was found to result in a long-term removal efficiency of less than 10%.Iron oxides can stimulate natural attenuation of ClO_(4)^(-).In fact,the attenuation process began to be affected when the concentration of dissolved iron was lower than 5.5 mg/L.Nitrate(NO_(3)^(-))in groundwater has an inhibitory effect on ClO_(4)^(-) reduction.When NO_(3)^(-) concentration was less than 10 mg/L,an apparent reduction in ClO_(4)^(-) could be initiated.