Ding Shuai, Zhang Shuai, Wang Yang, Chen Shuo, Chen Qing
Beijing Key Laboratory of Farmland Soil Pollution Prevention-control and Remediation, College of Resources and Environmental Sciences, China Agricultural University, No. 2 Yuanmingyuan Xilu, Haidian, Beijing, 100193, PR China.
Beijing Key Laboratory of Farmland Soil Pollution Prevention-control and Remediation, College of Resources and Environmental Sciences, China Agricultural University, No. 2 Yuanmingyuan Xilu, Haidian, Beijing, 100193, PR China; Key Laboratory of Arable Land Quality Monitoring and Evaluation, State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Ministry of Agriculture and Rural Affairs, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100081, PR China.
Environ Pollut. 2024 Feb 15;343:123204. doi: 10.1016/j.envpol.2023.123204. Epub 2023 Dec 22.
Colloid-facilitated phosphorus (P) migration plays an important role in P loss from farmland to adjacent water bodies. However, the dynamics of colloidal P (P) release as influenced by irrigation in alkaline calcareous soil remains a knowledge gap. The present study, monitored the dynamic change of P under different water management strategies: 1) control, 2) flooding, and 3) alternating flooding and drying cycles. Soil water-dispersible colloids (0.6 nm-1 μm) were extracted by combining filtration and ultrafiltration methods. The contents of P, cation and organic carbon in the water-dispersible colloids were determined and the stability and mineral composition of colloidal fractions were characterized. The results showed that P ranged from 16.5 to 25.5 mg kg and represented 42.8%-64.9% of the water-extracted P in the control. Flooding significantly decreased the P content by 16.0%-62.1% (mean 32.7%) and it may be attributed to the dissolution of colloidal iron (Fe) bound P. The alternating flooding and drying treatment significantly reduced the P content by 11.6%-88.0% (mean 67.6%). The P content of the flooding event was always greater than the P content of the drying event during flooding and drying cycles. Redundancy analysis and random forest modeling showed that the colloidal calcium (Ca) and ionic strength in soil solutions had negative correlations with the P content, and pH, ionic strength and truly dissolved P were the critical factors affecting P. Drying of the flooded soil led to the decrease of pH and the increase of ionic strength, colloidal Ca content and positive charges of colloid surfaces, which promoted colloid aggregation and enhanced soil P sorption capacity. This restricted the loss potential of P. In summary, controlled flooding and drainage when managed correctly have a role to play in mitigating P loss from P-enriched calcareous soils.
胶体促进的磷（P）迁移在磷从农田流失到相邻水体的过程中起着重要作用。然而，在碱性石灰性土壤中，灌溉对胶体磷（P）释放动态的影响仍是一个知识空白。本研究监测了不同水分管理策略下磷的动态变化：1）对照，2）淹水，3）淹水和干湿交替循环。通过过滤和超滤相结合的方法提取土壤水分散性胶体（0.6纳米 - 1微米）。测定了水分散性胶体中磷、阳离子和有机碳的含量，并对胶体组分的稳定性和矿物组成进行了表征。结果表明，对照处理中磷含量在16.5至25.5毫克/千克之间，占水提取磷的42.8% - 64.9%。淹水显著降低了磷含量16.0% - 62.1%（平均32.7%），这可能归因于胶体铁（Fe）结合磷的溶解。淹水和干湿交替处理显著降低了磷含量11.6% - 88.0%（平均67.6%）。在淹水和干湿循环过程中，淹水事件的磷含量始终大于干燥事件的磷含量。冗余分析和随机森林建模表明，土壤溶液中的胶体钙（Ca）和离子强度与磷含量呈负相关，pH、离子强度和真溶解磷是影响磷的关键因素。淹水土壤干燥导致pH降低，离子强度、胶体钙含量和胶体表面正电荷增加，促进了胶体凝聚，增强了土壤对磷的吸附能力。这限制了磷的流失潜力。总之，正确管理的控制性淹水和排水在减轻富磷石灰性土壤的磷流失方面具有作用。
