草酸青霉SL2对高浓度铬污染土壤的生物淋洗及胞内铬形态转化研究

Research on bioleaching of soils contaminated by high concentration of chromium with Penicillium oxalicum SL2 and the intracellular speciation transformation of chromium

铬渣无序堆存造成的铬污染土壤迫切需要修复治理.本文以新筛选的功能微生物草酸青霉SL2(Penicillium oxalicum SL2)为材料,以重度铬污染土壤为研究对象,进行生物淋洗技术优化,并利用软X射线扫描透射显微光谱技术(STXM)及同步辐射X射线近边吸收结构谱学(XANES)分析淋洗后的草酸青霉SL2胞内铬空间分布化学形态.结果表明:分步处理并进行水洗预处理可明显提高草酸青霉SL2对高浓度铬污染土壤的总铬TCr淋出率(49.4%),淋出液中Cr(VI)在3 d内全部被还原;生物淋洗后,草酸青霉SL2胞内吸收累积了Cr(VI),部分被还原为Cr(III),两个价态的Cr在空间分布上具有一定的一致性;胞内铬形态主要为磷酸铬、草酸铬钾及半胱氨酸铬类化合物,其含量分别为46.9%、33.0%和20.1%.

Chromium contaminated soils caused by disorderly stockpiling of chromium slags need to be remediated immediately. In this study,a newly isolated strain of functional fungus,Penicillium oxalicum SL2,was used as bioleaching material,soils contaminated by high concentration of chromium were used as study object and the bioleaching process was optimized. Scanning transmission X-ray microscope（ STXM） and synchrotron based X-ray absorption near edge structure（ XANES） technology were conducted for the analyzing of Cr accumulation,spatial distribution and chemical speciation in the intracellular of fungi P. oxalicum SL2 after bioleaching. The results showed that the leaching rate（ 49. 4%） of total chromium（ TCr） in soils contaminated by high concentration of chromium was significantly improved by two-step processing and washing pretreatment with P. oxalicum SL2,and the concentration of Cr（ VI） in the leachate was totally reduced in 3 d. After bioleaching,part of Cr（ VI） was absorbed and some other part was reduced to Cr（ III）,and spatial distribution of Cr（ VI） and Cr（ III） was consistent to a certain degree. The results of XANES showed that the intracellular Cr mainly consisted of chromium phosphate,potassium chromium oxalated and cysteine chromium analogue compounds,whose the proportion was 46.9,33.0 and20.1%,respectively.