地膜降解特征对不同土壤水分和温度条件的响应

Response of degradation characteristics of films to different soil moisture and soil temperature

以2种PBAT生物降解膜(生物降解膜1、生物降解膜2)和普通PE膜作为研究材料,采用室内培养试验,结合扫描电镜(SEM)和傅里叶红外光谱(FTIR)技术,探讨其在不同土壤水分和温度条件下的降解特征。结果表明,在20%土壤含水量,20℃、40℃、20℃(12 h)和40℃(12 h)昼夜交替(20℃/40℃)3种不同土壤温度条件下培养90 d,20℃/40℃土壤温度时普通PE膜、生物降解膜1、生物降解膜2的失重率最高,分别达2.89%、11.91%、8.33%。在20℃土壤温度,15%、20%、25%、30%4种不同土壤含水量条件下,PE膜降解程度无明显差异;生物降解膜1在土壤含水量为30%时失重率最高,为5.36%;生物降解膜2在土壤含水量为25%时失重率最高,为6.46%。依据FTIR图,推测培养90 d后2种生物降解膜发生了诺里什Ⅰ型反应,在20℃/40℃土壤温度下2种生物降解膜烃键伸缩振动明显,代表分子链断裂。SEM显示生物降解膜降解加深的形貌特征变化趋势符合基质掉落—裂纹/小穿透性孔洞—大面积裂纹/大穿透性孔洞的规律。由此得出,PBAT生物降解膜的降解程度明显高于PE膜,高温湿润的土壤环境有利于PBAT生物降解膜的降解。

Two PBAT biodegradable films(biodegradable film 1 and biodegradable film 2)and a PE film were used as research materi⁃als,and the degradation characteristics of different films were studied by indoor culture experiment,scanning electron microscopy(SEM)and Fourier transform infrared spectrum(FTIR)under different soil moisture and different temperature culture conditions.The results showed that,when the films were cultured for 90 d under three different soil temperature conditions of 20℃,40℃,20℃(12 h)and 40℃(12 h)day and night alternation(20℃/40℃)respectively at the soil moisture content of 20%,the weight loss rates of the common PE membrane,biodegradable film 1 and biodegradable film 2 were the highest at 20℃/40℃,reaching to 2.89%,11.91%,8.33%,respectively.When the films were cultured for 90 d at 15%,20%,25%and 30%soil mositure respectively at 20℃,there was no significant difference in the degradation degree of PE film,while the biodegradable film 1 had the highest weight loss rate of 5.36%at 30%soil mositure,and that of the biodegradable film 2 was 6.46%at 25%soil mositure.It could be speculated that the Nor⁃rish type I reactions occurred in the two biodegradable films after 90 d of culture based on the FTIR.The expansion vibration of the two biodegradable films was obvious at 20℃/40℃,representing the molecular strand fracture.SEM showed the change trend of the mor⁃phological characteristic of the PBAT biodegradable films degradation was consistent with the law of matrix drop—crack/small penetrat⁃ing holes—large area crack/large penetrating holes.It was concluded that the degradation degree of PBAT biodegradable films was sig⁃nificantly higher than that of PE film,and the high temperature and humid soil environment was conducive to the degradation of PBAT biodegradable films.