黑麦草与施肥对石油-铅-镉复合污染土壤微生物活性的影响

随着工业和农业生产的发展,重金属、有毒有机物及其复合污染土壤日益增多,其修复问题在世界范围内是一项具有挑战性的任务。以砂质壤土为试验对象,模拟石油-铅-镉复合污染,共设置4个处理:(1)对照处理,复合污染土壤(CK);(2)不施肥处理,复合污染土壤+黑麦草(NF);(3)施氮肥处理,复合污染土壤+黑麦草+氮肥(F1);(4)施氮肥和磷肥处理,复合污染土壤+黑麦草+氮肥+磷肥(F2),研究种植黑麦草与施肥处理对石油-铅-镉复合污染土壤微生物活性的影响,以期为污染土壤修复及环境影响评价提供初步的理论基础。结果表明:黑麦草与施肥对复合污染土壤基础呼吸、微生物量碳均有促进作用,处理NF、F1和F2的土壤基础呼吸强度比对照处理CK最高分别增加约20.94%,24.41%,42.69%,其中施加氮、磷肥(F2)对土壤基础呼吸影响最显著;第10天时,处理NF、F1和F2土壤微生物量碳含量与对照相比分别增加约26.92%,127.43%,181.89%,施肥处理土壤微生物量碳含量显著高于不施肥处理;不同种类的酶活性对黑麦草与施肥的响应不尽相同,其中种植黑麦草与施肥均会抑制石油-铅-镉复合污染土壤中FDA水解酶活性,施加氮肥在一定时间内能较好地维持石油-铅-镉复合污染土壤内的脱氢酶活性,施肥能有效地提高并维持复合污染土壤中脲酶活性,而过氧化氢酶活性受黑麦草与施肥影响不显著。研究表明种植黑麦草配施氮、磷肥对土壤微生物基础呼吸、土壤微生物量碳及相关土壤酶活性均有增强作用,进而有利于促进土壤污染物的去除及土壤质量的改善。

Effects of Ryegrass and Fertilization on Microbial Activity in Oil, Lead and Cadmium Co-contaminated Soil

Heavy metals mixed with toxic organics are increasingly contaminating soil with the development of the industry and the modernization of agricultural production, making remediation of the contaminated soils an urgent and challenging task. In this study, we set up 4 treatments with sandy loam as the test object:(1) Control group, co-contaminated soil (CK); (2) No fertilizer group, co-contaminated soil + ryegrass (NF); (3) Nitrogen fertilizer group, co-contaminated soil + ryegrass + nitrogen fertilizer (F1); (4) Nitrogen fertilizer and phosphate fertilizer group, co-contaminated soil + ryegrass + nitrogen fertilizer and phosphate fertilizer (F2). In order to provide a preliminary theoretical basis for remediation of contaminated soil and environmental impact assessment, we studied the effects of ryegrass and fertilization on microbial activity in oil, lead and cadmium co-contaminated soil. The results showed that both ryegrass and fertilization had positive effects on the soil basal respiration and microbial biomass carbon in the co-contaminated soil. Compared with the control, the peaks of basal soil respiration in NF, F1 and F2 increased by 20.94%, 24.41% and 42.69%, respectively. The effects of nitrogen and phosphate fertilizer (F2) on soil basic respiration were most significant. On the 10th day, the peaks of soil microbial biomass carbon in NF, F1 and F2 increased by 26.92%, 127.43% and 181.89%, respectively, indicating that fertilization treatments were better than non-fertilization. Various soil enzymes had different responses to ryegrass and fertilizer application. The activities of FDA hydrolysis were restrained in NF, F1 and F2, while the application of nitrogen fertilizer could maintain the dehydrogenase activity in the oil-lead-cadmium co-contaminated soil at a certain time. Fertilization could continuously and effectively improve and maintain the activity of urease in the oil-lead-cadmium co-contaminated soil. But there was little impact on the catalase activity. These findings implied that the soil microbial biomass, soil microbial biomass carbon and soil enzyme activity were enhanced by the application of nitrogen and phosphate fertilizer. It meant that planting ryegrass with nitrogen and phosphate fertilizer could promote soil pollutant removal and soil quality improvement.