施加牛粪有机肥对阿特拉津在灰钙土上吸附影响的机制
Effect Mechanism of the Organic Cattle Manure on the Sorption of Atrazine onto Sierozem
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摘要: 有机肥含有丰富的有机质和营养物质,然而在改良土壤的同时也会改变农药在土壤中的环境行为。为明确牛粪有机肥施加对灰钙土吸附阿特拉津(ATZ)的影响作用及机制,采用批量平衡振荡法,分析其吸附动力学、吸附热力学及牛粪施加量、pH、离子强度等影响因素对其吸附的影响作用及机制。结果表明:ATZ在灰钙土与施加牛粪灰钙土上的吸附过程均可分为快吸附和慢吸附直至平衡的过程,准二级动力学模型能较好地描述其吸附过程,有机肥的施加,增加了污染物在灰钙土上的吸附平衡时间,吸附速率受颗粒内扩散和外部液膜扩散共同作用。施加牛粪有机肥后,灰钙土对ATZ的吸附热力学更符合Freundlich模型,1/n在0.42~0.64之间,属于“L 型”等温吸附模式。低温和高温均会抑制ATZ在灰钙土上的吸附。pH值和共存离子是影响ATZ在灰钙土上吸附的重要因素,随pH的升高,ATZ在灰钙土与施加牛粪灰钙土的吸附量降低,这可能与ATZ的电离有关,碱性情况下,ATZ以阴离子存在,与带负电的灰钙土产生静电排斥作用。不同离子和离子强度对ATZ在灰钙土上的吸附影响结果不同,灰钙土对土壤溶液中离子具有较强的缓冲作用,施加牛粪有机肥后,对有机离子的吸附抑制作用明显,增加土壤溶液中的离子可能导致竞争吸附的存在,从而抑制有机离子在灰钙土上的吸附。ATZ在灰钙土上的吸附主要是离子交换、静电作用、氢键、范德华力和表面络合共同作用的结果;施加牛粪有机肥后,会改变ATZ在灰钙土上的吸附行为和机制,降低ATZ在灰钙土中的迁移风险。研究结果将为贫瘠黄土土壤改良风险和三嗪类农药的管控提供理论依据和参考。Abstract: Organic fertilizer is rich in organic matter and nutrients, which can improve the soil quality and also modify the environmental behavior of pesticides in the soil. To clarify the effect and mechanism of cattle manure on atrazine (ATZ) sorption in sierozem, the batch equilibrium methods were used to analyze the sorption dynamics, sorption thermodynamics, pH, ion types and strengths, and other influencing factors. The results showed that the sorption process of ATZ and sierozem applied cattle manures can be divided into fast sorption and slow sorption until equilibrium. The pseudo-second-order kinetic model can better describe the sorption process. The application of cattle manure fertilizer increases the sorption equilibrium time of pollutants in sierozem, and the sorption rate is combined by intraparticle diffusion and external liquid membrane diffusion. After the application of cattle manure fertilizer, the sorption thermodynamics of ATZ fitted well with the Freundlich model, with 1/n between 0.42 and 0.64, which belongs to the "L-type" isothermal sorption mode. Both low and high temperature will inhibit the sorption of ATZ on sierozem. The pH and coexisting ions are key factors affecting the sorption of ATZ on sierozem. With increasing pH values, the sorption capacities of ATZ on sierozem were decreased, which may be associated with ionization of ATZ, and in the alkaline case, ATZ is present as an anion, producing an electrostatic repulsion with the negatively charged sierozem. Different ions and ion strengths will be affecting the ATZ sorption on sierozem with a strong buffer effect, however, after application of organic manure fertilizer into sierozem, the increase the ions in soil solution may lead to the existence of competitive sorption between organic ions and cation on sorption sites in sierozem surface, thus inhibit the sorption of organic ions on sierozem. The sorption of ATZ on sierozem is mainly the result of ion exchange, electrostatic action, hydrogen bonding, van der Waals force and surface complexation. The results showed that the application of natural organic fertilizer such as cattle manure may lead to altered ATZ sorption behavior and mechanism, and the migration risk of ATZ in sierozem is reduced. Our results will be improved understand the risk of the application of natural organic fertilizer in barren loess soil, and provide theoretical basis and reference for the control of the triazine pesticides in the study areas.
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Key words:
- Atrazine /
- Organic Manure /
- Sierozem /
- Sorption /
- pH /
- Ion Types and Strengths
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