几种土壤酶活性对低分子量聚乙烯的响应

普通塑料地膜在自然条件下难以降解,环境可降解地膜则相对容易地降解形成大小不等的膜碎片样残留物,这一类低分子量残留物是否对环境造成危害,是当前急需证明的问题。研究低分子量聚乙烯(LMWPE)对土壤中几种关键酶活性的影响,对环境可降解地膜的推广使用具有重要意义。本研究利用不同分子量聚乙烯粉末,模拟可降解地膜降解后的聚乙烯组分,将不同分子量(2000、5000和10万以上)和不同累积量(1年量、10年量、50年量和100年量)的LMWPE粉末添加在土壤中,自然条件下盆栽种植蚕豆,研究土壤中三种关键酶对LMWPE处理的响应。结果显示,蚕豆苗期、开花初期、开花期、结荚鼓粒期和成熟期,LMWPE对土壤脲酶、过氧化物酶、碱性磷酸酶活性具有不同程度的激活作用,其中以添加LMW-PE分子量2000且累计量100年的处理(AS)对三种土壤酶的激活作用最为显著;随着LMWPE累计量增加,三种土壤酶活性增幅呈显著增加的趋势;LMWPE分子量处理对三种酶活性影响的差异大多未达显著水平;蚕豆根系的形成和生长对三种土壤酶活性具有显著影响。结果表明,在环境因素作用下可实现可降解地膜的无害化降解,低分子量聚乙烯可能具有改善土壤微环境的潜力。

Responses of Three Enzyme Activities to Lower Molecular Weight Polyethylene Added in Pot-cultured Horse Bean Soil

Biodegradable plastic mulch film was relatively easier to be degraded to form fragments of varying in sizes than ordinary plastic film under natural conditions.There was one of important problem need to be eagerly proved that the low molecular weight residues by degraded whether endanger the environments.The research into the effects of low molecular weight polyethylene(LMWPE) on several key enzyme activities in soil was of great significance in promoting use of biodegradable plastic mulch film in farm production.In the experiments LMWPE powder,that they were mainly component of biodegradable plastic mulch film,of different molecular weight(2000,5000,100000 above respectively) and different cumulants(1,10,50,100year respectively) were added into pot-loam soils in which horse bean were planted,and three key enzyme activities were studied for exploring the response to LMWPE treatments.The results showed that the activities of urease,peroxidase and alkaline phosphatase in the soil during whole growth periods of horse bean were activated inordinately;especially those were increased significantly in treatments with LMWPE 2000 molecular weight and 100 years cumulant(AS treatment).The more polyethylene was cumulated,the higher significantly the three enzyme activities,but there were no significant difference in lots of the treatments with LMWPE molecular weight.There were obvious effects of broad bean root growth on the three enzyme activities.It is suggested that innocuous degradation of plastic mulch film residues can be obtained and LMWPE may be of potential to improve the microenvironment in soil.