Change of Ecological Characteristics Due to Decrease of COD/SO_4^(2-) Ratio During Sulfate-reduction

In order to investigate the change of ecological characteristics due to the decrease of COD/SO_4^(2-) ratio during sulfate reduction, continuous-flew tests were conducted in an acidogenic sulfate-reducing reactor with molasses wastewater as sole organic carbon source and sodium snlfate as electron acceptor, and the change of pH value, oxidation reduction potential (ORP), volatile fat acids (VFAs), alkalinity (ALK) and the predominant populations with COD/SO_4^(2-) ratio decreasing from 4.2 to 2.0 were investigated. The experimental results demonstrated that, with decreasing COD/SO_4^(2-) ratio, ORP and ALK increased, pH value decreased, and the proportion of acetic acid in terminal products decreased significantly, and a stable -type microbial community with high COD/SO_4^(2-) ratio was converted into a sub -stable -type one with low COD/SO_4^(2-) ratio.

旱区地下水SO_(4)^(2-)来源与地下水循环分析

针对新疆库-新-沙地区SO_(4)^(2-)浓度与硫同位素特征,分析地下水化学及SO_(4)^(2-)分区特征和来源,进而判断该区域地下水的循环过程。结果表明,该区地下水水化学类型主要分为4种,水化学类型演变方向为HCO_(3)·Cl·SO_(4)^(2-)-Na·Mg·Ca→SO_(4)^(2-)·Cl-Na→Cl·SO_(4)^(2-)-Na·Mg→Cl-Na。不同地貌单元的离子浓度具有逐渐升高的趋势;SO_(4)^(2-)浓度具有明显的区域分异性,表现为北部低南部高,中部低东西部高;从上游补给区到下游排泄区水体中SO_(4)^(2-)浓度与δ34S值逐渐增高,说明不同地貌单元δ^(34)S的潜在来源发生了偏移或改变;地下水SO_(4)^(2-)来源总体表现为大气降水,陆相蒸发盐与海陆过渡相蒸发岩的溶滤及灌溉水的影响。基于此将研究区分为4个流域分别研究了各流域硫值与硫酸根沿程变化。