微塑料和菲对土壤化学性质、酶活性及微生物群落的影响

Effect of Microplastics and Phenanthrene on Soil Chemical Properties,Enzymatic Activities,and Microbial Communities

微塑料和多环芳烃(PAHs)因在土壤环境中广泛存在及其潜在生态风险而受到越来越多的关注.然而,关于微塑料-PAHs复合污染对土壤生态系统的影响鲜有报道.选用聚乙烯(PE)/聚丙烯(PP)和菲(PHE)作为微塑料和PAHs的代表,进行为期300d的微宇宙培养实验,利用土壤农业化学分析方法和16S扩增子测序技术研究PE/PP和PHE的单一和复合污染对土壤化学特性、酶活性和微生物群落(数量、结构、功能)的影响,分析PE/PP和PHE存在下土壤性质、酶活性和菌群的互作关系.结果表明,PE/PP和PHE的单一和复合污染对土壤pH值、有效磷(AP)和微生物(细菌、放线菌、霉菌)数量没有产生明显影响,但显著提高了荧光素二乙酸酯酶(FDAse)活性;PE、PP、PHE-PE和PHE-PP的添加显著增加了土壤有机质(SOM)含量和脲酶活性,PHE、PHEPE和PHE-PP显著增强了脱氢酶和磷酸酶活性及速效氮(AN)含量;PHE的添加对微生物群落影响不大,PE、PP、PHE-PE和PHE-PP对群落产生了一定的影响.PE/PP和PHE能够促进微生物产生能量、生长和繁殖,加快污染物的代谢/降解和细胞膜转运等功能.PE/PP和PHE引起的AN和SOM变化是影响土壤酶活性的关键因子,AN、AP和pH的改变是微生物数量增加的主要原因;微生物群落结构的改变与土壤化学性质、酶活性具有一定的相关性,其中SOM对菌群的影响达到了显著水平,土壤中不同碳源(PE/PP和PHE)的存在及菌与菌之间的互作关系也会影响微生物群落的组成.综上,PE/PP和PHE通过改变土壤化学性质、酶活性和微生物群落及其互作过程来促进菌群适应污染物胁迫.

Microplastic and polycyclic aromatic hydrocarbon(PAHs)pollution have received increasing attention due to their ubiquitous distribution and potential risks in soils.However,the effects of microplastics-PAHs combined pollution on soil ecosystems remain unclear.Polyethylene(PE)/polypropylene(PP)and phenanthrene(PHE)were selected as the representatives of microplastics and PAHs,respectively.A 300-day soil microcosm experiment was conducted to study the single and combined effects of PE/PP and PHE on soil chemical properties,enzymatic activities,and bacterial communities(i.e.,quantity,composition,and function),using the soil agricultural chemical analysis method and 16S amplicon sequencing technology.The interactions of soil properties,enzyme activities,and flora in the presence of PE/PP and PHE were analyzed.The results showed that the addition of PE/PP and PHE slightly changed the pH,available phosphorus(AP),and microbial quantity(i.e.,bacteria,actinomycetes,and mold)but considerably increased the fluorescein diacetate hydrolase(FDAse)activity.There was a significant enhancement of soil organic matter(SOM)and urease activity in PE,PP,PHE-PE,and PHE-PP amended systems.PHE,PHE-PE,and PHE-PP obviously increased the dehydrogenase/neutral phosphatase activities and available nitrogen(AN)content.PHE had little effect on the microbial community.The PE,PP,PHE-PE,and PHE-PP addition influenced the microbial community to some extent.PE/PP and PHE showed positive effects on the energy production,growth,and reproduction of soil microorganisms and then accelerated the metabolism/degradation of pollutants and membrane transport.The changes in AN and SOM induced by PE/PP and PHE were the key factors affecting soil enzyme activities.Alterations in AN,AP,and pH were mainly responsible for the increase in microbial population.The changes in the microbial community were related to soil chemical properties and enzyme activities,and SOM had a significant effect on the microbial community.The presence of different carbon sources(PE/PP and PHE)in the soil and the microbial interaction also affected the microbiota.In conclusion,the addition of single or combined pollutants of PE/PP and PHE influenced the soil chemical properties,enzymatic activities,bacterial communities,and their interaction processes,thus facilitating the adaptation of the microbial community to pollutant stress.