重金属污染区土壤酶活性变化——以福建龙岩新罗区特钢厂污水灌溉区为例

Changes of soil enzyme activities in heavy metals polluted region:A case study in a wastewater-irrigated agricultural area near a smelter in Xinluo District of Longyan City,Fujian Province

从福建龙岩新罗区特钢厂污灌区农田采集土壤,测定土壤基本理化性质及脲酶、纤维素酶、碱性磷酸酶、多酚氧化酶、过氧化氢酶活性和Cu、Cd、Pb、Zn含量,探讨重金属污染和土壤性质对土壤酶活性的影响.结果表明:4种全量或有效态重金属与土壤脲酶、纤维素酶、碱性磷酸酶和多酚氧化酶活性呈显著正相关,与过氧化氢酶活性呈显著或极显著负相关;土壤pH与碱性磷酸酶活性呈极显著正相关,粉粒含量与过氧化氢酶活性呈显著负相关.经通径分析,重金属污染刺激了脲酶、多酚氧化酶和纤维素酶活性,但对碱性磷酸酶活性的影响较小.有效态Cu、Cd、Pb、Zn对过氧化氢酶活性的直接影响并不大,但通过间接途径抑制了过氧化氢酶活性.土壤理化性质对5种土壤酶活性的影响较大,碱解氮直接抑制了脲酶活性;全磷直接刺激了碱性磷酸酶和过氧化氢酶活性,并通过有效磷刺激了纤维素酶活性;有效磷直接刺激了纤维素酶活性,直接抑制了碱性磷酸酶和过氧化氢酶活性;全钾直接抑制了碱性磷酸酶和多酚氧化酶活性;速效钾通过有效磷刺激了纤维素酶活性;土壤颗粒组成明显影响多酚氧化酶和过氧化氢酶活性.5种酶活性与土壤Cu、Cd、Pb、Zn含量之间的关系不明确,因此其活性不是指示土壤Cu、Cd、Pb、Zn污染的良好指标.

Surface soil samples were collected from a wastewater-irrigated agricultural area near a smelter in the Xinluo District of Longyan City,Fujian Province,and their basic physical and chemical properties,activities of urease,cellulase,alkaline phosphomonoesterase,polyphenol oxidase and catalase,and contents of Cu,Cd,Pb and Zn were determined,aimed to approach the effects of heavy metals pollution and soil properties on the activities of soil enzymes. Correlation analysis showed that the total and available contents of soil Cu,Cd,Pb and Zn had significant positive correlations with the activities of soil urease,cellulase,alkaline phosphomonoesterase and polyphenol oxidase,but significant negative correlation with the activity of soil catalase. Soil pH had significant positive correlation with the activity of soil alkaline phosphomonoesterase,and soil silt content had significant negative correlation with the activity of soil catalase. Path analysis showed that Cu,Cd,Pb and Zn pollution promoted the activities of soil urease,cellulase and polyphenol oxidase,but had less effects on the activity of soil alkaline phosphomonoesterase. Soil available Cu,Cd,Pb and Zn didn＇t directly affect the activity of soil catalase,but indirectly inhibited it significantly. Soil physical and chemical properties had greater effects on soil enzyme activities,e.g.,alkaline-hydrolyzable N directly inhibited the activity of soil urease,total P directly stimulated the activities of soil alkaline phosphomonoesterase and catalase and indirectly stimulated the activity of soil cellulase via available P,available P directly promoted the activity of soil cellulase but inhibited the activities of soil alkaline phosphomonoesterase and catalase,total K directly inhibited the activities of soil alkaline phosphomonoesterase and polyphenol oxidase,available K stimulated the activity of soil catalase via available P,and particle composition had significant effects on the activities of soil polyphenol oxidase and catalase. The above results demonstrated that because of the complicated and uncertain relationships between the contents of soil Cd,Pb,Zn and Cu and the activities of the five soil enzymes,it should be cautious to use the test enzyme activities to indicate soil heavy metals pollution.