Enhanced remediation of Cd-contaminated calcareous soil with herbage by wood vinegar

Abstract

为探究木醋液强化牧草对石灰性重金属污染农田土壤的修复效果，本研究设计双因素裂区田间试验，牧草为主因素，木醋液施用浓度（稀释400、200、100倍）为副因素，分析木醋液对黑麦草、紫花苜蓿生长情况，重金属镉（Cd）富集积累以及收获期根际土壤 Cd 含量等方面影响。结果表明：施用木醋液后黑麦草和紫花苜蓿地上部生物量较 T0（清水对照）处理最高分别提高12.85%和20.00%（P<0.05），Cd地上部积累量较T0处理分别显著增加46.08%~181.68%和88.53%~150.15%（P<0.05），黑麦草各处理地上部Cd积累量，较紫花苜蓿高出12.07~35.31 g·hm^-2。随着木醋液施加量的增加，黑麦草和紫花苜蓿土壤脲酶和蔗糖酶活性显著增加，但土壤过氧化氢酶活性无显著变化。收获期黑麦草、紫花苜蓿根际土壤Cd含量较种植前显著降低（P<0.05），分别下降11.69%~25.67% 和 15.35%~17.43%，其中黑麦草 T3 处理（木醋液稀释 100 倍）修复效果最佳，根际土壤 Cd 含量较种植前降低25.67%。综上，土壤中施用木醋液可有效提高土壤Cd的生物有效性，强化植物对重金属富集积累，从而提高牧草的修复效果。

A two-factor split-zone field experiment was designed to investigate the remediation effect of wood vinegar-enhanced herbage on calcareous soil polluted by heavy metals. The herbage was the main treatment, and the concentration of wood vinegar was the subtreatment. The effects of wood vinegar on the growth of ryegrass and alfalfa, enrichment and accumulation of heavy metal cadmium（Cd）, the physical and chemical indexes of rhizosphere soil, and the Cd content during harvest were analyzed. The results showed that the aboveground biomass of ryegrass and alfalfa increased significantly by 12.85% and 20.00%（P<0.05）after the application of wood vinegar compared with T0（water control）treatment, the Cd accumulation in the above-ground parts respectively by 46.08%–181.68% and 88.53%– 150.15% compared with T0 treatment, and ryegrass was 12.07–35.31 g·hm^-2 higher than alfalfa. With the increase in wood vinegar, the soil urease and sucrase activities of ryegrass and alfalfa increased significantly, but there was no significant effect on soil catalase activity. The Cd content in rhizosphere soil of ryegrass and alfalfa at the harvest stage was significantly lower than that before planting（P<0.05）, which decreased by 11.69%-25.67% and 15.35%-17.43% respectively. Among them, the ryegrass T3（wood vinegar diluted 100 times）treatment had the best remediation effect, and the rhizosphere soil Cd content was reduced by 25.67 % compared with that before planting. In conclusion, applying wood vinegar in soil can effectively improve the bioavailability of Cd in soil, strengthen the enrichment and accumulation of heavy metals in plants, and thus improve the remediation effect of herbage.