不同淋洗剂淋洗对镉污染农田土壤微生物群落结构的影响

Effect of soil washing with different washing agents on the structure of microbial community in agricultural soil contaminated with cadmium

土壤微生物群落对重金属污染土壤修复效果有较好的响应.为评价不同淋洗剂淋洗对镉(Cd)污染农田土壤微生物群落结构的影响,选用Cd污染土壤常用的乙二胺四亚甲基膦酸(EDTMP)和乙二胺四乙酸(EDTA)作为供试淋洗剂,对采自矿区周边Cd重度污染农田土壤进行室内浸提试验,分别测定了浸提后土壤微生物群落结构、Cd的化学形态和部分理化性质.结果表明,EDTMP和EDTA浸提对土壤Cd都具有一定的去除效果,其单次浸提率分别为14.23%和38.93%.浸提后土壤优势菌群结构发生明显变化,经EDTMP浸提土壤变形菌门相对丰度显著提高,而土壤酸杆菌门和硝化螺旋菌门的相对丰度则显著降低;经EDTA浸提土壤拟杆菌门相对丰度显著降低.经EDTMP浸提土壤的变形菌门、拟杆菌门和浮霉菌门的相对丰度显著高于经EDTA浸提土壤,芽单胞菌门和硝化螺旋菌门的相对丰度则显著低于经EDTA浸提后的土壤(p<0.05).冗余分析(RDA)结果表明,2种淋洗剂主要通过降低土壤Cd含量、改变土壤pH及主要养分含量来影响微生物群落结构.

It is well known that soil microbial communities have a good response to the remediation effect of soils contaminated with heavy metals. To evaluate the effect of different washing agents on the structure of soil microbial community,a simulation washing test was performed with a heavily cadmium(Cd)-polluted agricultural soils collected around mining area. The effects of two commonly used washing agents,ethylene-diaminetetramethylene phosphoric acid(EDTMP)and ethylene diamine tetraacetic acid(EDTA),on the structure of microbial communities,chemical forms of Cd and some physicochemical properties of the test soils were compared. The results showed that both agents had low to moderate efficiencies after single washing,with 14.23% and 38.93% Cd removal being obtained for EDTMP and EDTA,respectively. Substantial changes in the dominant bacterial phyla after soil washing were observed. The relative abundance of Proteobacteria in the EDTMP-washed soil increased significantly,whereas Acidobacteria and Nitrospirae decreased. In contrast,the relative abundance of Bacteroidetes decreased significantly in the EDTA-washed soil. In the soil washed with EDTMP,Proteobacteria,Bacteroidetes and Planctomycetes were considerably higher,and Gemmatimonadetes and Nitrospirae were significantly lower than in those washed with EDTA(p < 0.05). Redundancy analysis(RDA)indicated that these two washing agents influenced the structure of microbial community by reducing the concentration of Cd,altering soil pH and main soil nutrient contents.