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首页> 外文期刊>Environmental Science & Technology >Stimulation Of Microbial Urea Hydrolysis In Groundwater To Enhance Calcite Precipitation
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Stimulation Of Microbial Urea Hydrolysis In Groundwater To Enhance Calcite Precipitation

机译：刺激地下水中微生物尿素水解以增强方解石沉淀

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Addition of molasses and urea was tested as a means of stimulating microbial urea hydrolysis in the Eastern Snake River Plain Aquifer in Idaho. Ureolysis is an integral component of a novel remediation approach for divalent trace metal and radionuclide contaminants in groundwater and associated geomedia, where the contaminants are immobilized by coprecipitation in calcite. Generation of carbonate alkalinity from ureolysis promotes calcite precipitation. In calcite-saturated aquifers, this represents a potential long-term contaminant sequestration mechanism. In a single-well experiment dilute molasses was injected three times over two weeks to promote overall microbial growth, followed by one urea injection. With molasses addition, total cell numbers in the groundwater increased 1-2 orders of magnitude. Estimated ureolysis rates in recovered groundwater samples increased from <0.1 to >25 nmol L~(-1) hr~(-1). A quantitative PCR assay for the bacterial ureC gene indicated that urease gene numbers increased up to 170 times above pre-injection levels. Following urea injection, calcite precipitates were recovered. Estimated values for an in situ first order ureolysis rate constant ranged from 0.016 to 0.057 d~(-1). Although collateral impacts such as reduced permeability were observed, overall results indicated the viability of manipulating biogeochemical processes to promote contaminant sequestration.
机译：在爱达荷州的蛇河平原含水层中，添加糖蜜和尿素作为刺激微生物尿素水解的方法进行了测试。对于地下水和相关地质介质中的二价痕量金属和放射性核素污染物，尿解是一种新颖的补救方法的组成部分，该污染物通过方解石中的共沉淀而固定化。尿素分解产生的碳酸盐碱度促进了方解石沉淀。在方解石饱和含水层中，这代表了潜在的长期污染物螯合机制。在单孔实验中，在两周内注射了3次稀糖蜜，以促进总体微生物生长，然后再注射一次尿素。加入糖蜜后，地下水中的总细胞数增加了1-2个数量级。回收的地下水样品中估计的尿素分解速率从<0.1增加到> 25 nmol L〜（-1）hr〜（-1）。细菌ureC基因的定量PCR分析表明，脲酶基因数量增加到注射前水平的170倍。注入尿素后，方解石沉淀得以回收。原位一阶尿素分解速率常数的估计值范围为0.016至0.057 d〜（-1）。尽管观察到了诸如降低渗透率之类的附带影响，但总体结果表明，操纵生物地球化学过程以促进污染物螯合的可行性。

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