聚乙烯微塑料对土壤养分和酶活性的影响

Effects of Polyethylene Microplastics on Soil Nutrients and Enzyme Activities

微塑料污染对土壤生态系统的威胁引起了广泛关注.为了明确聚乙烯微塑料对土壤性质的影响,通过为期4个月的土壤培养试验,探究不同质量分数(1%、2.5%、5%)和粒径(30目、100目)聚乙烯微塑料对土壤化学性质、养分含量和酶活性的影响.结果表明:①100目2.5%和5%微塑料处理显著降低了土壤pH,不同质量分数和粒径聚乙烯微塑料添加对土壤电导率影响不显著.②相比于CK,添加微塑料会不同程度降低土壤速效钾、有效磷和硝态氮含量.添加100目微塑料显著增加了土壤有机质和铵态氮含量.③当微塑料粒径为100目时,相比于CK,不同质量分数处理均显著提高了土壤过氧化氢酶和碱性磷酸酶活性,5%处理显著降低了土壤蔗糖酶活性.④土壤性质的变化受微塑料质量分数和粒径影响,质量分数越高、粒径越小,影响越显著.综上,聚乙烯微塑料对土壤性质的影响没有预期的明显,未来研究应重点关注不同影响所涉及的机制问题.

The threat of microplastic pollution in soil ecosystems has caused widespread concern.In order to clarify the effect of polyethylene microplastics on soil properties,a 4-month soil incubation experiment was conducted in this study to investigate the effect of different mass fraction(1%,2.5%,and 5%)and particle sizes(30 mesh and 100 mesh)of polyethylene microplastics on soil chemical properties,nutrient contents,and enzyme activities.The results showed that:①When the particle size was 100 mesh,microplastics at the mass concentrations of the 2.5%and 5%treatments significantly reduced soil pH,and the exposure of polyethylene microplastics had no significant effect on soil conductivity.②Compared to that in CK,the addition of microplastics reduced soil available potassium,available phosphorus,and nitrate nitrogen to varying degrees.The addition of 100 mesh microplastics significantly increased soil organic matter and ammonium nitrogen.③When the particle size was 100 mesh,compared to that in CK,treatments of all concentrations significantly increased soil catalase activity and alkaline phosphatase,showing an increasing but not significant trend,and the 5%concentration treatment significantly decreased soil sucrase activity.④Changes in soil properties were influenced by the addition of microplastics of different concentrations and sizes,with higher concentrations and smaller particle sizes having more significant effects.In conclusion,the effects of microplastics on soil properties were not as pronounced as expected,and future research should focus on the mechanisms involved in the different effects.