连续施用改性生物质炭对镉铅土壤修复效果及其对微生物群落结构的影响

为探究磷酸改性生物质炭对石灰性污染土壤重金属的稳定效果及对微生物群落结构的影响,于2015-2019年选择豫北某地污染农田土壤开展连续5 a的定位试验。研究选用磷酸改性稻壳生物质炭为土壤调理剂,设置土壤调理剂不同年限的连续施用处理,分析土壤有效态镉、铅含量及小麦籽粒镉、铅含量,以探究调理剂钝化效果的持续性,借助高通量测序技术测定连续施用调理剂对耕地土壤微生物群落结构的影响。结果表明:本研究选用的磷酸改性稻壳生物质炭虽一定程度上降低了石灰性土壤的pH,但土壤中有效态镉、铅含量显著减少,不同年限连续施用土壤调理剂最终都能显著抑制小麦籽粒中镉、铅的积累。与不添加土壤调理剂的对照处理相比,各处理土壤有效态镉、铅含量分别降低32%~46%和24%~36%,小麦籽粒镉、铅含量降幅为17%~43%和9%~35%。此外,调理剂显著提升了细菌Pseudolabrys和Nordella以及真菌Mortierella的丰度,降低了细菌Nocardioides和Bryobacter以及真菌Gibberella和Sarocladium的丰度。研究表明,连续施用5 a调理剂后小麦籽粒镉含量达到最低值,施加调理剂3 a即可显著降低小麦籽粒中铅含量;施用调理剂对土壤微生物群落结构产生一定的影响,改善了土壤细菌群落的多样性及丰富度。

Remediation effect of continuous application of modified biochar on cadmium- and lead-contaminated soil and its effect on microbial community structure

In order to explore the stabilization effect of phosphoric acid-modified biochar on heavy metals in calcareous contaminated soil and the effect on microbial community structure, a 5-year trial was conducted in northern Henan Province from 2015 to 2019. In this study, phosphoric acid-modified rice husk biochar was selected as a soil modifier, and its continuous application during different years was conducted to analyze cadmium and lead contents in wheat grains and to explore the sustainability of its effect. Additionally, soil microbial diversity was also measured by high-throughput sequencing technology. The results showed that phosphoric acid-modified rice husk biochar used in this study reduced the pH of the calcareous soil to a certain extent. Available cadmium and lead contents in the soil were significantly reduced. Application of the soil modifier in different years could inhibit the accumulation of cadmium and lead in wheat grains. Compared to treatments without adding soil modifier, all treatments reduced the available soil cadmium and lead contents by 32%~46% and 24%~36%, respectively. Cadmium and lead contents in wheat grains decreased by 17%~43% and 9%~35%, respectively. In addition, the soil modifier significantly increased the abundance of Pseudolabrys and Nordella bacteria and Mortierella fungi, but decreased the abundance of Nocardioides and Bryobacter bacteria and Gibberella and Sarocladium fungi. It was observed that cadmium content in wheat grains reached the lowest level after continuous application of the soil modifier for 5 years, while lead content in wheat grains could be significantly reduced after application for 3 years. The application of a soil modifier had a certain impact on the soil microbial community structure and improved the diversity and richness of the soil bacterial community.