稻秆生物炭和蜡状芽孢杆菌联合作用对土壤重金属形态转化及微生物群落的影响

EFFECT OF COMBINATION OF RICE STRAW BIOCHAR AND BACILLUS CEREUS ON TRANSFORMATION OF SOIL HEAVY METAL SPECIATIONS AND MICROBIAL COMMUNITY

为了明确稻秆生物炭和芽孢杆菌的联合作用对铜、镉污染土壤的重金属形态转化及微生物群落的作用机理,通过土壤培养试验,对比分析了土壤中Cu和Cd不同形态的含量、土壤化学性质和酶活性的变化特征,采用高通量测序技术阐明土壤微生物群落的响应规律。结果表明:生物炭和微生物(BC+M)处理后,土壤Cu和Cd酸提取态下降尤为显著,含量分别降低27.35%和27.48%;BC+M能显著提高土壤pH值,增强土壤有效磷、速效钾和过氧化氢酶活性,分别提高了114.16%、462.76%和113.79%;酸提取态Cu和Cd含量与pH、碱解氮(AN)、有效磷(AP)、速效钾(AK)、阳离子交换量(CEC)和有机质(SOM)呈负相关,但酸提取态Cu与AK、AP显著负相关(P<0.05),酸提取态Cd与AK、pH显著负相关(P<0.05);BC+M处理显著提高土壤微生物群落多样性,主要提高了Chloroflexi、Actinobacteriota、Firmicutes、Acidobacteriota和Bacteroidota等对重金属具有较强耐性的优势菌群丰度,相比真菌群落,细菌群落对土壤环境因子变化的响应更加强烈,尤其是Proteobacteria、Chloroflexi、Firmicutes、Acidobacteriota和Bacteroidota。稻秆生物炭与芽孢杆菌主要通过影响土壤pH值、AP、AK和细菌群落结构,从而使土壤Cu和Cd酸提取态向其他形态转化,这可为土壤重金属污染微生物修复提供理论参考。

To determine the combined effect of rice straw biochar and Bacillus on the transformation of heavy metal speciation and the mechanisms affecting microbial communities in Cu-Cd contaminated soil,the contents of different speciation of Cu and Cd in soil,soil chemical properties and enzyme activities were compared and analyzed through soil culture experiments.The structure composition and diversity response patterns of soil microbial communities were investigated by high-throughput sequencing technology.The results indicated that after biochar and microbial(BC+M)treatment,the acid-extractable Cu and Cd contents decreased significantly,and the contents decreased by 27.35%and 27.48%,respectively.BC+M significantly enhanced soil pH value,and enhanced soil available phosphorus,available potassium and catalase activity by 114.16%,462.76%and 113.79%,respectively.Acid-extracted Cu and Cd were negatively correlated with pH,alkali-hydrolyzed nitrogen(AN),available phosphorus(AP),available potassium(AK),cation exchange capacity(CEC)and organic matter(SOM),but acid-extracted Cu was significantly negatively correlated with AK and AP(P<0.05),and acid-extracted Cd was significantly negatively correlated with AK and pH(P<0.05).The BC+M treatment significantly diversified the soil microbial communities,mainly increasing the abundance of dominant bacterial groups such as Chloroflexi,Actinobacteriota,Firmicutes,Acidobacteriota and Bacteroidota,which are known for strong resistance to heavy metals.Compared to fungal communities,bacterial communities respond more intensely to changes in soil environmental factors,especially Proteobacteria,Chloroflexi,Firmicutes,Acidobacteriota and Bacteroidota.Rice straw biochar and Bacillus primarily affect soil pH,AP,AK and the structure of the bacterial community,thereby facilitating the transformation of acid-extractable forms of Cu and Cd into other potentially less harmful states.This provides a theoretical reference for the microbial processes in soil heavy metal pollution remediation.