不同钝化机制矿物对土壤重金属的钝化效果及微生物响应

Effects of minerals with different immobilization mechanisms on heavy metals availability and soil microbial response

为探讨石灰石、蒙脱石两种不同钝化机制矿物施加对土壤重金属的钝化效果和土壤环境健康的影响,利用盆栽试验,通过常规测定方法和16S rRNA高通量测序手段,分析土壤酶活性和微生物群落结构的变化,并结合土壤重金属有效性、水稻富集系数和转运系数等指标,研究两种矿物施加后土壤的环境功能响应及其影响机制。结果表明:施加石灰石显著降低了土壤Cd、Cu、Pb、Zn的有效性,降低幅度依次为Zn(99.1%)>Cd(91.4%)>Cu(85.6%)>Pb(46.1%),并显著降低了Cd、Zn的富集系数(43.4%~85.5%)和转运系数(Cd 62.5%、Zn 30.0%),而施加蒙脱石使土壤Pb的有效性降低幅度达19.5%,但其含量与对照差异不显著;施加石灰石显著提高了土壤过氧化氢酶和脲酶活性,均为对照(不施加钝化剂)的1.6倍,施加蒙脱石后土壤过氧化氢酶活性显著提高(为对照的1.4倍),但脲酶活性没有明显变化;施加蒙脱石对土壤微生物多样性和微生物群落结构影响较小,但施加石灰石后,土壤微生物多样性指数显著增加,且f_Gemmatimonadaceae、f_BIrii41和c_KD4-96等有益微生物属的丰度明显提高。研究表明,与通过吸附对重金属钝化的蒙脱石相比,石灰石通过提升土壤pH,不但能更有效地降低土壤中Cd、Cu、Pb、Zn等重金属的生物有效性,还能提升土壤酶活性和微生物的多样性,从而改善土壤健康状况,其中土壤pH、有效磷和有机质含量是影响微生物群落结构的关键因素。

The goals of this study are to elucidate the effects of minerals,including limestone and montmorillonite,on the heavy metal availability and soil health.A pot trial was conducted to examine the effects of the two aforementioned minerals on heavy metals availability,enzyme activities,and microbial community structure in metal-contaminated farmland soils by traditional testing methods and 16S rRNA high throughput sequencing.Additionally,their effects on biological concentrations and translocation factors of heavy metals in rice,the relationships between microbial community structure and physicochemical properties,and factor regulating them were analyzed.The results showed that limestone application decreased the availabilities of Cd,Cu,Pb,and Zn,with decreases of 99.1%for Zn,91.4%for Cd,85.6%for Cu,and 46.1%for Pb.Moreover,limestone application also significantly reduced the biological concentration factors(43.4%~85.5%)and translocation factors(Cd 62.5%and Zn 30.0%).In contrast,the application of montmorillonite decreased the availability of only Pb(19.5%decrease).Consistently,urease and catalase activities in the limestone treated soil were 1.6 times higher than those of the control,whereas catalase activity in the montmorillonite amended soils also increased 1.4 times,although urease activity did not increase significantly.Additionally,the application of montmorillonite did not affect the microbial community structure significantly,whereas the application of limestone significantly increased microbial community diversity.The beneficial bacterial genera f_Gemmatimonadaceae,f_BIrii41,and c_KD4-96,which are vital for phosphate dissolution and microbial nitrogen metabolism,were also enriched.Overall,our study shows that the limestone application decrease the availabilities of Cd,Cu,Pb,and Zn,and improve soil health.The soil microbial community is determined by soil pH,and available P and soil organic matter contents.