花生壳生物炭对镉污染菜园土壤细菌群落结构的影响

Effect of peanut shell biochar on the bacterial community structure in cadmium-containing vegetable soil

为进一步了解不同镉污染水平下生物炭对土壤镉钝化和环境效应,利用盆栽试验模拟研究3个土壤镉水平(0、2.5和5.0mg/kg)和5个生物炭添加量(0、5、10、20和40g/kg)下菜园土壤酶活性和细菌群落的变化.菜园土壤pH随着花生壳生物炭施用量的增加而增加,并与62%土壤细菌显著相关.不同镉污染菜园土壤中过氧化氢酶、碱性磷酸酶和脲酶活性均以20 g/kg和40 g/kg花生壳生物炭施用量时分别达到最大值和最小值.Saccharibacteria、Burkholderia-Paraburkholderia和Sphingomona等部分高丰度细菌与过氧化氢酶、碱性磷酸酶或者脲酶显著相关.40 g/kg花生壳生物炭和5.0 mg/kg重金属镉处理的土壤细菌群落结构与其他处理有显著差异,对菜园土壤细菌产生双重的抑制作用.添加花生壳生物炭的处理,土壤中高丰度细菌受重金属镉的影响不显著.花生壳生物炭施用量改变菜园土壤的pH值和土壤酶活性(过氧化氢酶、碱性磷酸酶和脲酶),从而影响菜园土壤的细菌群落结构.在重金属镉浓度<5.0 mg/kg条件下下,20 g/kg花生壳生物炭施用量更有利于改善土壤的理化性质,减轻重金属镉的毒害作用和促使细菌群落的恢复生长和提高土壤酶活性.(图10表3参61)

To further understand the passivation and environmental effects of biochar on different cadmium pollution soils, potted experiments were conducted. The effects of different cadmium levels(Cd 0, 2.5, and 5.0 mg/kg) and biochar additions(0, 5, 10, 20, and 40 g/kg) on soil enzyme activity and the soil bacterial community were examined. The pH of vegetable soil increased with increased concentrations of peanut shell biochar, which was significantly correlated with 62% of the soil bacteria. The catalase, alkaline phosphatase, and urease activities of vegetable soil reached maximum and minimum levels with the application of 20 g/kg and 40 g/kg of the peanut shell biochar, respectively. Bacteria such as Saccharibacteria, Burkholderia-Paraburkholderia, and Sphingomon, among others, were observed in high abundance and were significantly correlated with catalase, alkaline phosphatase, or urease. The bacterial community structure of the 40 g/kg peanut shell biochar and 5.0 mg/kg cadmium treatment was significantly different from that of other treatments, which had a dual inhibitory effect on bacteria in vegetable soil. The bacteria with the highest abundance were not significantly affected by cadmium when peanut shell biochar was added to vegetable soil. The pH and soil enzyme activity(catalase, alkaline phosphatase, and urease) of vegetable soil may have been altered by the amount of peanut shell biochar applied, and consequently this may have affected the structure of the soil bacterial community. When the acidic soils contaminated by cadmium(< 5.0 mg/kg) were remedied, the application amount of 20 g/kg peanut shell biochar was superior at improving soil physicochemical properties, reducing the toxic effect of cadmium, and promoting the recovery and growth of the soil bacterial community and enzyme activity.