改性沸石改良底泥对土壤中微生物生物量碳及酶活性的影响

Effects of zeolite-modified sediment on microbial biomass carbon and enzyme activity in soil

为了减小底泥中重金属的活性,实现底泥回田再利用,以洞庭湖重金属污染底泥为实验对象,探究以Na Cl和壳聚糖改性沸石改良的底泥对土壤中微生物生物量碳和生物酶(脲酶和脱氢酶)活性的影响。实验结果表明,两种沸石改良底泥添加后,土壤中水溶态金属浓度减小。Na Cl改性沸石处理组(沸石/底泥质量比3/7)和壳聚糖改性沸石处理组(沸石/底泥质量比1/9、3/7和6/4)中微生物量碳含量增加,微生物量C/N比最大提高至原来的2.8倍。壳聚糖改性沸石添加底泥对土壤生物酶影响较Na Cl改性沸石明显,土壤脲酶和脱氢酶活性随壳聚糖改性沸石投加量的增加而明显提升,壳聚糖改性沸石最大投加量组中(6/4)脲酶和脱氢酶活性较对照组分别增大1.1、1.6倍。

Heavy metals within the sediment will lead to soil contamination and subsequently cause harmful effects on human beings and organisms if the highly contaminated or not properly managed sediment is disposed on land. In this context, the use of the adsorbent zeolite might be a promising strategy to absorb and stabilize heavy metals in sediments, therefore reducing their mobility and increasing potential to make the sediment for beneficial reuse. In this study, we investigated the influence of two modified Dongting Lake sediments（modified by Na Cl and chitosan zeolite）on microbial biomass carbon and two enzyme activities（i.e. urease and dehydrogenase）in soils. Results showed that upon the addition of two zeolite-modified sediments, water soluble metal content in the soil was reduced. Microbial biomass carbon was increased in a Na Cl-modified zeolite treatment（zeolite：sediment mass ratio of 3/7）and three chitosan-modified zeolite treatments（zeolite：sediment mass ratio of 1/9, 3/7, and 6/4）, and microbial biomass C/N ratio was approximately increased by 2.8-fold. In addition, chitosanmodified zeolite treatment had a greater impact on soil enzyme activities than Na Cl-modified zeolite treatment. Urease activity and dehydro-genase activity in the highest dose of chitosan-modified zeolite treatment（zeolite：sediment mass ratio of 6/4） was increased by 1.1-and1.6-fold, respectively. Therefore, the addition of chitosan-modified zeolite as amendment was an effective technique for sediment remedia-tion, which allows for a possible end point for the dredged sediment.