典型塑料添加剂在土壤-植物系统中的迁移特征研究
- Migration characteristics of typical plastic additives in soil-plant system
- 基金项目：国家自然科学(No. 22106138,42177265)，浙江省属高校基本科研业务费专项资金资助（No. QRK22003）
- 摘要：农田土壤中微塑料存在广泛，微塑料作为源头，在老化的过程中会释放大量内源性添加剂进入土壤，导致部分农田正面临塑料添加剂的污染.因此，我们以苯并三唑类紫外线吸收剂和邻苯二甲酸酯类增塑剂为典型塑料添加剂，分析其在土壤-植物系统中的界面迁移行为.在土壤吸附塑料添加剂的过程中，土壤有机质起主导作用，土壤有机质含量与吸附能力正相关（线性模型R2＞0.98）.土壤中的蒙脱石因多孔结构和高比表面积，吸附效能显著高于高岭石.在根基材料吸附塑料添加剂的过程中，根系脂质可通过疏水作用主导塑料添加剂的吸附，脂质去除后吸附量下降40%；纤维素多孔结构通过物理吸附辅助固持污染物.另外，根系有机酸抑制其吸附，果糖则可增强其疏水分配作用.土壤中水溶态/酸溶态塑料添加剂含量与叶部积累水平显著相关，根系生物富集因子与塑料添加剂的logKow值正相关（p＜0.01），说明高疏水性添加剂易滞留根系；转移因子与logKow值负相关（p＜0.01），说明地上部积累受限.本研究揭示了塑料添加剂在土壤-植物系统的迁移特征，为其生态风险评估与修复提供理论支撑.
- Abstract：Microplastics are pervasively present in agricultural soils, where they act as a persistent reservoir of endogenous additives released through aging processes. It has led to widespread contamination of farmlands with additives derived from plastics. In this study, we conducted a systematic investigation into the interfacial adsorption and transport characteristics of two representative plastic additives (benzotriazole ultraviolet absorbers and phthalate plasticizers) in the soil-plant continuum. Results indicated that soil organic matter (SOM) played a crucial role in the adsorption process of plastic additives. A strong positive correlation was observed between SOM content and adsorption capacity of plastic additives, as evidenced by an R2 value exceeding 0.98 in linear regression. A comparative analysis further revealed that montmorillonite exhibited higher adsorption efficiency compared to kaolinite, primarily due to its superior porosity and larger specific surface area. On the root interface, hydrophobic interactions mediated by root lipids were identified as the predominant adsorption mechanism for plastic additives. And the lipid extraction led to a 40% reduction in adsorption amounts of plastic additives. Specifically, the porous cellulose matrix in roots also contributed to the physical immobilization of contaminants. Besides, the organic acids and fructose in root exudates demonstrated the combined effects. Notably, the significant correlations were found between the bioavailability of these additives in soils (as measured by water/acid-soluble fractions) and their accumulation levels in plant foliage. The root bioconcentration factor exhibited a positive correlation with logKow values (p < 0.01), suggesting that the preferential retention of highly hydrophobic additives in roots. Conversely, the translocation factor showed an inverse relationship with logKow (p < 0.01), suggesting the restricted aerial transport of these contaminants. These findings would provide valuable mechanistic insights into the fate and transport of plastic additives in agricultural ecosystems, laying a scientific foundation for the assessment of ecological risk and soil remediation.
