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论文题目：Effect of conventional and biodegradable microplastics on the soil-soybean system: A perspective on rhizosphere microbial community and soil element cycling

论文作者：Tianjiao Song, Jiaxi Liu, Siqi Han, Yan Li, Tengqi Xu, Jiao Xi, Lijun Hou, Yanbing Lin*

论文摘要：

As an exogenous carbon input, microplastics (MPs), especially biodegradable MPs, may significantly disrupt soil microbial communities and soil element cycling (CNPS cycling), but few studies have focused on this. Here, we focused on assessing the effects of conventional low-density polyethylene (LDPE), biodegradable polybutylene adipate terephthalate (PBAT), and polylactic acid (PLA) MPs on rhizosphere microbial communities and CNPS cycling in a soil-soybean system. The results showed that PBAT-MPs and PLA-MPs were more detrimental to soybean growth than LDPE-MPs, resulting in a reduction in shoot nitrogen (14.05% and 11.84%) and shoot biomass (33.80% and 28.09%) at podding stage. In addition, dissolved organic carbon (DOC) increased by 20.91% and 66.59%, while nitrate nitrogen (NO- 3-N) significantly decreased by 56.91% and 69.65% in soils treated with PBAT-MPs and PLA-MPs, respectively. PBAT-MPs and PLA-MPs mainly enhanced copiotrophic bacteria (Proteobacteria) and suppressed oligotrophic bacteria (Verrucomicrobiota, Gemmatimonadota, etc.), increasing the abundance of CNPS cycling-related functional genes. LDPE-MPs tended to enrich oligotrophic bacteria (Verrucomicrobiota, etc.) and decrease the abundance of CNPS cycling-related functional genes. Correlation analysis revealed that MPs with different degradation properties selectively affected the composition and function of the bacterial community, resulting in changes in the availability of soil nutrients (especially NO- 3-N). Redundancy analysis further indicated that NO- 3-N was the primary constraining factor for soybean growth. This study provides a new perspective for revealing the underlying ecological effects of MPs on soil-plant systems.

可生物降解塑料虽被视为减少传统不可降解塑料污染的解决方案，但在自然环境中难以如期降解，可能产生更多的微塑料，对土壤生态构成威胁。目前，研究发现，与传统微塑料相比，可生物降解微塑料对植物有更大的负面影响。鉴于可生物降解微塑料较高的生物可利用性，其可能会显著改变根际微生物群落组成，干扰根际土壤元素循环，从而影响植物生长。然而，有关微塑料对此方面的影响及其潜在的生态效应尚未被阐明。

该研究以大豆为模式作物，通过室内微控盆栽试验模拟农田土壤微塑料污染现状，重点探究了传统不可降解的低密度聚乙烯（LDPE）微塑料、可生物降解的聚己二酸对苯二甲酸丁二醇酯（PBAT）和聚乳酸（PLA）微塑料对大豆根际微生物群落及碳氮磷硫循环的影响，并对土壤理化及植物生长进行评估，以此揭示传统和可生物降解微塑料对土壤-植物体系潜在的生态效应。研究结果表明，可生物降解微塑料比传统微塑料更不利于大豆生长，其降低大豆叶绿素含量及地上生物量。此外，可生物降解微塑料提高了土壤可溶性有机碳含量，但显著减少土壤硝态氮含量。可生物降解微塑料主要促进富营养微生物，并显著增加碳氮磷硫循环相关功能基因丰度。传统微塑料则倾向于富集寡营养微生物，并降低碳氮磷硫循环相关功能基因丰度。相关性分析表明，具备不同降解性质的微塑料选择性地影响细菌群落的组成和功能，最终导致土壤养分（如硝态氮）可用性的变化。值得注意的是，RDA分析进一步表明硝态氮是大豆生长的主要限制因子。该研究强调了微塑料暴露导致的根际微生物群落的改变和养分失衡的风险，为揭示不同类型的微塑料对土壤-植物体系潜在的生态效应提供了新的证据和见解。

论文链接：https://doi.org/10.1016/j.envint.2024.108781