微塑料对亚热带不同富铁程度红壤团聚体稳定性 及碳氮磷化学计量特征的影响.

[Objective] The present paper aimed to investigate the effects of microplastics on the structure and carbon, nitrogen, phosphorus stoichiometric characteristics of red soil with different levels of iron enrichment, and to provide theoretical basis for guiding the improvement of soil quality and pollution management in red soil areas. [Method] Using subtropical red soil as the research object, low density polyethylene (M0, M1, M2) with 0, 0.1%, 1.0% mass and iron (Fe0, Fe1, Fe2) with 0, 10 and 20 g/kg mass were added through indoor cultivation experiments to simulate the pollution level of microplastics and the degree of iron enrichment in red soil. The distribution characteristics of water stable aggregates and the stoichiometric characteristics of carbon, nitrogen and phosphorus in red soil polluted by microplastics under different iron enrichment conditions were studied. [Result] Under the condition of Fe0o, compared with M0, the aggregate content (WSA), mean weight diameter (MWD) and geometric mean diameter (GMD) of M1 with particle size > 0.25 mm decreased, and the WSA, MWD and GMD of M2 increased significantly; Under Fe0, conditions, there was no significant difference in the stability indicators of aggregates among M0, M1 and M2; Under Fe2 conditions, both M1 and M2 significantly reduced the WSA, MWD and GMD of soil aggregates. In terms of carbon, nitrogen and phosphorus content and their stoichiometric characteristics, M1 and M2 under Fe0 conditions could significantly increase soil organic carbon content (SOC); Under Fe0, and Fe2 conditions, microplastic treatment had no significant effect on SOC. The total nitrogen content (TN) of the soil decreased significantly under Fe0, and Fe1, conditions, while microplastic treatment had no significant effect on TN under Fe2 conditions; The total phosphorus content (TP) of the soil showed M0 > M1 > M2. The changes in soil nutrients ultimately led to a significant increase in C/N, C/P and N/P of all microplastic treatments (except for Fe0, M1, Fe2 M1 and Fe2 M2). [Conclusion] The effects of different treatments on the stability of soil aggregates vary. Under the current existing red soil conditions, low micro plastic pollution can reduce the stability of soil aggregates, while high micro plastic pollution can increase the stability of soil aggregates. Under relatively light iron rich red soil conditions, both low and high microplastic pollution have no significant impact on the stability of soil aggregates. Under relatively high iron rich red soil conditions, both low and high microplastic pollution can reduce the stability of soil aggregates. M0reover, the changes in soil aggregate structure under different treatments led to significant differences in the stoichiometric characteristics of carbon, nitrogen and phosphorus in the soil. Overall, microplastic pollution can significantly improve the C/N, C/P and N/P of red soil. [ABSTRACT FROM AUTHOR]