可降解地膜的生物降解作用研究

Study on Biodegradation of Degradable Mulching Film

为了解生物因素在地膜降解过程中的作用,通过室内模拟试验,研究了6种不同可降解地膜在南疆2种典型土壤林灌草甸土、亚高山草甸土中的生物降解情况。结果表明,在相同的温度和湿度条件下,6种地膜的生物降解差异很大,其中陕西膜X 1的CO2累积释放量远远高于其他5种地膜。同种地膜在不同土壤中的生物降解也表现出差异性,其中差异最大的为PE膜,在林灌草甸土中的CO2累积释放量高于亚高山草甸土的4倍左右。最后通过研究地膜的生物降解模型,发现地膜在生物降解过程均符合一元多项式方程,即Polynomial Fit,且都达到了极显著水平(P<0.01),模拟方程的一般形态为:y=a+bx+cx2+dx3+…,并且呈现出一定的变化规律。因此,地膜进入诱导期以后,在一定的时间尺度内,生物降解发挥着主要作用,开始由碎片状低聚物在微生物和生物酶作用下水解变成尺寸更小的碎片进行生物降解,最后被吞噬细胞吸收,或进一步水解,生成CO2和H2O,其降解规律均符合Polynomid Fit模型。

In order to study the biodegradation of biodegradable plastic films,the simulated experiment studied the degradation of 6 different biodegradable plastic films in the Shrub meadow soil and the Subalpine meadow soil of Nangjiang.The results showed that during these 6 different biodegradable plastic films,the cumulative CO_2 emission of Shaanxi X-1 was more than others.For the same film,its degradation was different in different types of soil.PE film showed the biggest difference,the cumulative CO_2 emission of which was 4 times in the Shrub meadow soil more than in the Subalpine meadow soil.The diodegradation of biodegradable plastic films applied with Polynomial Fit model and all reached the significant level（P0.01）,with the equation y=a＋bx＋cx2＋dx3＋….Above all,biodegradation plays a main role after film enters the induction period.Debris shape oligomer makes smaller by the action of microbes and enzymes,and finally is absorbed by engulfed cells,or further hydrolyzed to generate CO_2 and H_2O.The degradation law is in line with Polynomid Fit model.