干旱区污灌农田土壤Cu、Ni复合污染与土壤酶活性的关系

Relationships Between Soil Enzymatic Activities and Cu-Ni Compounds Pollution in the Wastewater Irrigated Farmland in Arid Region

以重工业城市——甘肃省金昌市农业土壤为主要研究对象,采用室内分析测试方法,就污灌土壤重金属复合污染对酶的活性及微生物学参数进行了调查研究。结果表明,污灌区农田土壤中Cu、Ni重金属含量均超过土壤环境质量标准(GB15618—1995)中一级标准限量,但未达到二级标准。污灌区农田Cu、Ni复合污染对土壤脲酶、酸性磷酸酶和碱性磷酸酶活性均表现为激活作用;对过氧化氢酶和转化酶的抑制作用较小,而对多酚氧化酶的抑制作用较强,因此,多酚氧化酶可做为土壤Cu、Ni复合污染监测和评价的主要生化指标。污灌农田土壤微生物生物量和基础呼吸速率显著高于清灌土壤。除pH与转化酶活性之间呈显著(P<0.01)正相关关系外,其他土壤理化因子与土壤酶活性和微生物参数之间均呈显著(P<0.05或P<0.01)的正或负的相关关系,在污灌土壤中Cu、Ni复合污染对酶活性所表现出的屏蔽效应可能受到土壤有机质的影响。

The wastewater irrigated farmland soils from suburb around Jinchang City, Gansu Province, P. R. China, a typical industrialized city, were investigated in terms of enzymatic activities and microbial biomass resulted from soil heavy metal combined pollution. The results showed that the concentrations of Cu and Ni in the wastewater irrigated farmland soils were higher than the first-class limit value but lower than the second-class limit value set in the national Soil Environmental Quality Standard GB15618--1995. Cu-Ni combined pollution in the wastewater irrigated farmland soils exhibited stimulating effect on soil urease, acid phosphatase and alkaline phosphatase activities, but strong inhibition effect on polyphenol oxidase with less inhibition effect on peroxidase and invertase activities. This implied that the polyphenol oxidase could be used as the main biochemical index for monitoring and evaluating soil quality of Cu-Ni combined soils. The soil microbial biomass and basal respiration in the wastewater irrigated farmland soils were significantly higher than those in non-irrigated farmland soils. There were significant positive or negative relationships between the soil physical or chemical properties and the soil enzyme activities or microbial biomass parameters with the exception of the remarkably positive relationship between pH and invertase activities, and the protective effect of enzyme activities resulted from Cu-Ni combined pollution may be affected by soil organic matters.