农田土壤胶体对微塑料颗粒迁移的影响及机制研究进展

【目的】土壤胶体因具备巨大比表面积、较小粒径、携带大量电荷的特性,在吸附微塑料颗粒、影响微塑料颗粒迁移过程中发挥着重要作用。但是有关土壤尤其是农田土壤胶体对微塑料颗粒迁移的影响及其协同迁移机制尚不清晰。土壤胶体与微塑料颗粒定义模糊、分类标准各异等问题形成的认知误区也阻碍了对两者更为深入的研究。梳理国内外关于农田土壤胶体与微塑料颗粒的相关研究,旨在厘清农田土壤胶体与微塑料颗粒迁移过程中两者间的相互作用过程,为制定微塑料污染防治政策和措施提供理论依据。【主要进展】农业活动改变了土壤胶体颗粒的组成,影响了微塑料颗粒的迁移行为。土壤胶体、微塑料颗粒自身与多孔介质特性、土壤理化性质以及环境条件,通过协同促进和抑制两种机制影响着农田土壤胶体与微塑料颗粒的协同迁移。在此过程中,土壤胶体组成处于主导地位,土壤胶体颗粒的稳定性大小决定着其与微塑料颗粒的协同迁移状态。土壤胶体颗粒的吸附行为改变了微塑料颗粒的迁移路径和速率;微塑料颗粒的存在反过来也能影响土壤胶体颗粒的稳定性,改变其聚集态势,进而影响胶体颗粒的迁移能力。【展望】今后应细化不同性质农田土壤胶体与微塑料颗粒迁移机制研究,定量分析深入评估微塑料颗粒迁移的环境效应,探索土壤微生物−胶体−微塑料三者之间交互作用过程,从土壤物理、化学和生物学角度为修复微塑料污染土壤,守护土壤健康提供新的思路和借鉴。

Using ^(137)Cs Tracer Technique to Evaluate Erosion and Deposition of Black Soil in Northeast China

Soil and water losses through erosion have been serious in the black soil region of Northeast China. Therefore, a sloping cultivated land in Songnen Plain was selected as a case study to: 1) determine the 137Cs reference inventory in the study area; 2) calculate erosion and deposition rates of black soil on different slope locations; 3) conduct a sensitivity analysis of some model parameters; and 4) compare overall outputs using four different models. Three transects were set in the field with five slope locations for each transect, including summit, shoulder-slope, back-slope, foot-slope, and toe-slope. Field measurements and model simulation were used to estimate a bomb-derived 137Cs reference inventory in the study area. Soil erosion and deposition rates were estimated using four 137Cs models and percentage of 137Cs loss/gain. The 137Cs reference value in the study area was 2 232.8 Bq m-2 with 137Cs showing a clear topographic pattern, decreasing from the summit to shoulder-slope, then increasing again at the foot-slope and reaching a maximum at the toe-slope. Predicted soil redistribution rates for different slope locations varied. Among models, the Yang Model (YANG-M) overestimated erosion loss but underestimated deposition. However, the standard mass balance model (MBM1) gave predictions similar to a mass balance model incorporating soil movement by tillage (MBM2). Sensitivity analysis of the proportion factor 7 and distribution pattern of 137Cs in the surface layer demonstrated the impact of 137Cs enrichment on calculation of the soil erosion rate. Factors influencing the redistribution of fallout 137Cs in landscape should be fully considered as calculating soil redistribution rate using 137Cs technique.

Short-term Effects of Tillage Practices on Organic Carbon in Clay Loam Soil of Northeast China

一个耕种实验，由犁板组成犁( MP )，山脉耕种( RT )，和没有耕种( NT )，与四在一个使随机化的完全的块图案被执行复制在东北中国在粘壤土土壤的表面层( 30 厘米)在 SOC 内容和它的分发上学习3年的耕种管理的效果。NT 没与 MP 和 RT 相比在表层土(0 5 厘米) 导致 SOC 的重要增加；然而，在 NT 土壤的 SOC 内容显著地在 5 20 厘米的深度被减少。因此，短期(3 年) NT 管理趋于成层 SOC 集中，然而并非必然增加它在为土壤的犁层的存储。

Short-Term Impacts of No Tillage on Aggregate-Associated C in Black Soil of Northeast China

In order to get a good indicator to evaluate the impacts of no tillage （NT） on soil structure and soil quality, we studied the dynamics of total soil organic carbon （SOC） and aggregate-associated SOC, and their relationships in the plow layer （30 cm） in black soil of Northeast China under NT practice. The tillage experiment was established in Dehui County, Jilin Province, China, in 2001. The total SOC and aggregate-associated SOC under 5-yr tillage treatments were measured. NT practices did not lead to the increase of average SOC content at 0-30 cm depth, but it did significantly increase SOC at the top soil （0-5 cm）. In NT plots, the change of SOC in 〉 1 000 μm aggregate was the same with that of total SOC, but the effect of NT on SOC in 〉 1 000 lain aggregate was greater than the effect on total SOC, suggesting that 〉 1 000 μm aggregate had more sensitive response to the impact of tillage practices. Also, significant positive correlation occurred between total SOC and SOC in 〉 1 000 μm aggregate in black soil. Consequently, in the short term soil macroaggregate 〉 1 000 μm could be used as an indicator to evaluate the impacts of tillage practices on soil structure in black soil of Northeast China.