Abstract: The chemical behaviour of cesium (Cs) is extremely similar to that of potassium (K),and Cs that enters the body will accumulate in muscle and liver. To study the biotoxicity of stable cesium-133 (¹³³Cs),in this research we used ¹³³Cs and set three cesium treatments in microcosm:5 mg·kg^-1 Cs (CK),100 mg·kg^-1 Cs (L) and 500 mg·kg^-1 Cs (H) to investigate the effects of cesium on the functional diversity and enzyme activity of soils. The results showed that organic matter content,and available potassium content in Cs treatment were significantly decreased compared with that of CK (P<0.05),and those in H treatment were decreased by 13.54%,and 8.37%,respectively. Cs significantly decreased the activities of invertase,phosphatase,urease and dehydrogenase (P<0.05),and the inhibitory effect was enhanced with the increase of Cs concentration. In H treatment,it was reduced by 21.1%,22.5%,22.6% and 21.8%,respectively. Shannon diversity index,Shannon evenness index and carbon source utilization richness index were significantly decreased by Cs (P<0.05). The above results showed that cesium metal pollution significantly reduced the functional diversity of soil microbial community,reduced soil nutrient content,and inhibited soil enzyme activity. This study provided a theoretical basis for the risk control of stable cesium contaminated soils.

Key words: cesium, soil microbial, soil nutrient, enzymatic activity

摘要： 铯(Cs)与钾(K)的化学行为极其相似，进入人体后的Cs大量聚集到肌肉和肝脏中。为研究稳定性铯-133(¹³³Cs)的生物毒性，本研究采用¹³³Cs，通过微宇宙培养试验，设置3个铯处理浓度：5 mg·kg^-1 Cs(CK)，100 mg·kg^-1 Cs(L)和500 mg·kg^-1 Cs(H)，研究了金属铯对土壤理化性质和微生物群落功能多样性和酶活性的影响。结果表明，Cs处理中有机质含量和速效钾与CK相比显著减少(P＜0.05)，在H处理中分别降低了13.54%和8.37%。Cs显著降低了转化酶、磷酸酶、脲酶和脱氢酶活性(P＜0.05)，且随着Cs浓度的增加，其抑制效应增强，在H处理中分别减少了21.1%，22.5%，22.6%和21.8%。Cs显著降低了Shannon多样性指数、Shannon均匀度指数和碳源利用丰富度指数(P＜0.05)。以上结果表明金属铯污染显著降低土壤微生物群落的功能多样性，降低了土壤养分含量，抑制了土壤酶活性，该研究为¹³³Cs污染土壤的风险控制提供理论基础。

关键词: 铯, 土壤微生物, 土壤养分, 酶活性