稻草对土壤中铬的形态变化及微生物活性的影响

Effects of Rice Straw on the Speciation of Chromium and Microbial Activity in Soil

通过向添有外源Cr(Ⅵ)的土壤中施入一定量的粉碎稻草,研究了稻草对土壤中铬的形态变化特征:包括Cr(Ⅵ)含量的变化、有效态铬含量的变化以及铬形态分布特征的影响.实验结果表明,施入稻草可以促进Cr(Ⅵ)的还原,加快土壤中Cr(Ⅵ)和有效态铬含量的降低;同时,铬的形态分析表明,施入稻草的土壤水溶态和交换态铬含量比未施稻草的土壤低,而沉淀态和有机结合态铬含量比未施稻草的土壤高.实验还探讨了稻草对Cr(Ⅵ)污染土壤微生物活性的影响.结果表明,施入稻草的土壤呼吸强度和微生物数量都比未施稻草的土壤高,增施稻草对缓解Cr(Ⅵ)对土壤微生物的抑制作用有一定的效果.

The effects of smashed rice straw on the variation of speciation, including the variation of Cr（Ⅵ） content and available chromium content, and speciation distribution of chromium forms in Cr（Ⅵ）-amended soil were investigated, Rice straw was found to promote the reduction of Cr（Ⅵ）, and accelerate the decrease of Cr （Ⅵ） and available chromium content in soil. The water soluble chromium content and exchangeable chromium content were both lower in soil amended with rice straw than those in soil without rice straw, but the content of precipitated chromium and chromium bound to organic matter were both higher in soil with rice straw, compared with those in soil without rice straw. The effects of rice straw on the microbial activity in Cr（Ⅵ）-amended soil were also studied. The soil respiration intensity and microbial number were higher in soil amended with rice straw than those in soil without rice straw, indicating that the addition of rice straw alleviates the inhibitory effect of Cr（Ⅵ） on microorganisms in soil.