College of Environment and Safety Engineering, Qingdao University of Science and Technology, Qingdao, Shandong Province 266042, PR China.
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
J Hazard Mater. 2023 Jun 5;451:131152. doi: 10.1016/j.jhazmat.2023.131152. Epub 2023 Mar 5.
Both nitrogen deposition (ND) and microplastics (MPs) pose global change challenges. The effects of MPs co-existing with ND on ecosystem functions are still largely unknown. Herein, we conducted a 10-month soil incubation experiment to explore the effects of polyethylene (PE) and polylactic acid (PLA) MPs on soil multifunctionality under different ND scenarios. We found that the interactions between ND and MPs affected soil multifucntionality. FAPROTAX function prediction indicated that both ND and MPs affected C and N cycling. ND increased some C-cycling processes, such as cellulolysis, ligninolysis, and plastic degradation. MPs also showed stimulating effects on these processes, particularly in the soil with ND. ND significantly decreased the abundance of functional genes NifH, amoA, and NirK, leading to inhibited N-fixation, nitrification, and denitrification. The addition of MPs also modified N-cycling processes: 0.1% PE enriched the bacterial groups for nitrate reduction, nitrate respiration, nitrite respiration, and nitrate ammonification, and 1% PLA MPs enriched N-fixation bacteria at all ND levels. We found that ND caused lower soil pH but higher soil N, decreased bacterial diversity and richness, and changed the composition and activity of functional bacteria, which explains why ND changed soil functions and regulated the impact of MPs.
氮沉降（ND）和微塑料（MPs）都对全球变化构成挑战。 MPs 与 ND 共存对生态系统功能的影响在很大程度上仍然未知。在此，我们进行了为期 10 个月的土壤培养实验，以探索不同 ND 情景下聚乙烯（PE）和聚乳酸（PLA） MPs 对土壤多功能性的影响。我们发现 ND 和 MPs 之间的相互作用影响了土壤多功能性。FAPROTAX 功能预测表明，ND 和 MPs 都影响 C 和 N 循环。ND 增加了一些 C 循环过程，如纤维素分解、木质素分解和塑料降解。 MPs 也对这些过程表现出刺激作用，特别是在 ND 土壤中。ND 显著降低了功能基因 NifH、amoA 和 NirK 的丰度，导致固氮、硝化和反硝化受到抑制。添加 MPs 也改变了 N 循环过程：0.1%PE 富集了硝酸盐还原、硝酸盐呼吸、亚硝酸盐呼吸和硝酸盐氨化的细菌群，而 1%PLA MPs 在所有 ND 水平下富集了固氮细菌。我们发现 ND 导致土壤 pH 值降低但 N 含量升高，降低了细菌多样性和丰富度，并改变了功能细菌的组成和活性，这解释了为什么 ND 会改变土壤功能并调节 MPs 的影响。
