Dindar Efsun
Department of Environmental Engineering, Faculty of Engineering, Bursa Uludag University, Bursa 16059, Turkey.
Polymers (Basel). 2025 Jun 6;17(12):1586. doi: 10.3390/polym17121586.
Microplastics (MPs) are emerging contaminants that can significantly impact soil nutrient dynamics, particularly phosphorus (P) cycling, which is critical for maintaining soil fertility and ecosystem productivity. However, limited information is available on how different microplastic types and concentrations specifically influence phosphorus dynamics and microbial enzyme activity in soils. Microplastic contamination may alter P cycling by directly supplying phosphorus or indirectly influencing microbial activity and enzyme function through changes in soil structure and aggregation. This study examined the short-term impacts of three widely used microplastic polymers-polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET)-on soil phosphorus forms and alkaline phosphatase activity (APA), a key enzyme in phosphorus transformation. Incubation experiments were conducted at two concentrations (0.5% and 5%) over 30 and 60 days. The results indicated that the impact of microplastics on soil phosphorus dynamics varied according to both polymer type and contamination dose. Microplastics increased available phosphorus (AP) and APA levels compared to control soils, indicating a stimulatory effect on microbial processes. This may be due to the temporary accumulation of phosphorus on MP surfaces, which can stimulate phosphatase activity. Over time, however, both AP and APA levels declined, suggesting that degradation products released from MPs and organic matter may have altered the activity of the microbial communities responsible for P cycling. FTIR analysis revealed clear degradation of microplastics, with PET showing the most pronounced chemical transformation. PP exhibited moderate degradation, while PE demonstrated the highest resistance to environmental breakdown. These degradation processes likely released functional groups (e.g., carboxyl, carbonyl, hydroxyl) and low-molecular-weight compounds into the soil, modifying microbial processes and phosphorus chemistry. Particularly in PET-amended soils, these degradation products may have enhanced phosphate complexation or mobilization, contributing to higher levels of available phosphorus at the end of the incubation time. Understanding the polymer-specific and concentration-dependent effects of microplastics is critical for accurate ecological risk assessment in terrestrial ecosystems.
微塑料（MPs）是新出现的污染物，会对土壤养分动态产生重大影响，尤其是磷（P）循环，而磷循环对于维持土壤肥力和生态系统生产力至关重要。然而，关于不同类型和浓度的微塑料如何具体影响土壤中磷的动态以及微生物酶活性的信息有限。微塑料污染可能通过直接供应磷或通过改变土壤结构和团聚体间接影响微生物活性和酶功能来改变磷循环。本研究考察了三种广泛使用的微塑料聚合物——聚乙烯（PE）、聚丙烯（PP）和聚对苯二甲酸乙二酯（PET）——对土壤磷形态和碱性磷酸酶活性（APA，磷转化中的关键酶）的短期影响。在两种浓度（0.5%和5%）下进行了为期30天和60天的培养实验。结果表明，微塑料对土壤磷动态的影响因聚合物类型和污染剂量而异。与对照土壤相比，微塑料增加了有效磷（AP）和APA水平，表明对微生物过程有刺激作用。这可能是由于磷在微塑料表面的暂时积累，从而刺激了磷酸酶活性。然而，随着时间的推移，AP和APA水平均下降，这表明微塑料释放的降解产物和有机物可能改变了负责磷循环的微生物群落的活性。傅里叶变换红外光谱（FTIR）分析显示微塑料有明显降解，PET的化学转化最为显著。PP表现出中等程度的降解，而PE对环境分解的抵抗力最强。这些降解过程可能向土壤中释放了官能团（如羧基、羰基、羟基）和低分子量化合物，改变了微生物过程和磷化学性质。特别是在添加PET的土壤中，这些降解产物可能增强了磷酸盐的络合或迁移，导致培养期结束时有效磷水平升高。了解微塑料的聚合物特异性和浓度依赖性影响对于陆地生态系统中准确的生态风险评估至关重要。
