Microplastics threaten soil ecosystems, strongly influencing carbon (C) and nitrogen (N) contents. Interactions between microplastic properties and climatic and edaphic factors are poorly understood. We conducted a meta-analysis to assess the interactive effects of microplastic properties (type, shape, size, and content), native soil properties (texture, pH, and dissolved organic carbon (DOC)) and climatic factors (precipitation and temperature) on C and N contents in soil. We found that low-density polyethylene reduced total nitrogen (TN) content, whereas biodegradable polylactic acid led to a decrease in soil organic carbon (SOC). Microplastic fragments especially depleted TN, reducing aggregate stability, increasing N-mineralization and leaching, and consequently increasing the soil C/N ratio. Microplastic size affected outcomes; those <200 μm reduced both TN and SOC contents. Mineralization-induced nutrient losses were greatest at microplastic contents between 1 and 2.5% of soil weight. Sandy soils suffered the highest microplastic contamination-induced nutrient depletion. Alkaline soils showed the greatest SOC depletion, suggesting high SOC degradability. In low-DOC soils, microplastic contamination caused 2-fold greater TN depletion than in soils with high DOC. Sites with high precipitation and temperature had greatest decrease in TN and SOC contents. In conclusion, there are complex interactions determining microplastic impacts on soil health. Microplastic contamination always risks soil C and N depletion, but the severity depends on microplastic characteristics, native soil properties, and climatic conditions, with potential exacerbation by greenhouse emission-induced climate change.

中文翻译：

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添加的微塑料、原生土壤特性和普遍的气候条件是否会对土壤中的碳和氮含量产生影响？盆栽和温室研究的全球数据综合

微塑料威胁土壤生态系统，强烈影响碳 (C) 和氮 (N) 含量。人们对微塑料特性与气候和土壤因素之间的相互作用知之甚少。我们进行了一项荟萃分析，以评估微塑料特性（类型、形状、大小和含量）、原生土壤特性（质地、pH 值和溶解有机碳 (DOC)）和气候因素（降水和温度）对土壤中的C和N含量。我们发现低密度聚乙烯降低了总氮（TN）含量，而可生物降解的聚乳酸则导致土壤有机碳（SOC）降低。微塑料碎片尤其会消耗总氮，降低团聚体稳定性，增加氮矿化和淋溶，从而增加土壤碳氮比。微塑料大小影响结果； <200 μm 的颗粒降低了 TN 和 SOC 含量。当微塑料含量为土壤重量的 1% 至 2.5% 时，矿化引起的养分损失最大。沙质土壤因微塑料污染引起的养分消耗最为严重。碱性土壤表现出最大的 SOC 消耗，表明 SOC 降解性较高。在低 DOC 土壤中，微塑料污染导致的 TN 消耗比高 DOC 土壤高 2 倍。降水量高、温度高的站点TN和SOC含量下降幅度最大。总之，存在复杂的相互作用决定微塑料对土壤健康的影响。微塑料污染总是带来土壤碳和氮消耗的风险，但其严重程度取决于微塑料特征、原生土壤特性和气候条件，温室气体排放引起的气候变化可能会加剧这种污染。