Key Laboratory for Environmental Factors Control of Agro-Product Quality Safety, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China; Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China.
Key Laboratory for Environmental Factors Control of Agro-Product Quality Safety, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China; Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China.
Sci Total Environ. 2020 Jun 1;719:137440. doi: 10.1016/j.scitotenv.2020.137440. Epub 2020 Feb 20.
Organic matter effectively regulates nanoparticles transport. However, little is known about the effect of agricultural organic inputs on the transport of ferrihydrite nanoparticles (FHNPs) during aging. In this study, columns were filled with sand mixed with varying proportions of pristine, water-processing, or alkali-processing biochar or swine manure and used to simulate the release of organic matter and changes in surface roughness of sand grains during field aging. The influence of these factors on FHNPs transport was investigated using column experiments. The dissolved organic matter (DOM) (0.008-24.8 mg L) released from agricultural organic inputs decreased the zeta potential of the FHNPs from 30.8 mV to 14.6--48.9 mV and further caused electrostatic repulsion, osmotic repulsion, and elastic-steric repulsion between FHNPs and mixed sand, thus enhancing FHNPs transport. Ferrihydrite nanoparticles transport increased with increasing content of biochar and swine manure due to the increased amount of DOM. However, with the presence of organic inputs, surface roughness up to a certain degree (the increase in specific surface area up to 4.6 m) became the dominant inhibition factor affecting FHNPs transport. After DOM release, agricultural organic inputs decreased the enhancement of FHNPs transport; with the increase input, their rougher surface gradually increased inhibition of FHNPs transport. The strongest FHNPs retention in the alkali-processing biochar (0.2-10%) or swine manure (1-2%) mixed sand columns indicated that fully aged agricultural organic inputs strongly inhibited FHNPs transport. Our findings provided novel insights into the critical influence of agricultural organic inputs and their aging on FHNPs transport, which changed gradually from enhancement to inhibition gradually.
有机物可有效调控纳米颗粒的迁移。然而，对于农业有机输入物在老化过程中对针铁矿纳米颗粒（FHNPs）迁移的影响还知之甚少。本研究通过填充含有原状、水热和碱热生物炭或猪粪的混合砂柱来模拟野外老化过程中有机物的释放和砂粒表面粗糙度的变化，以研究这些因素对 FHNPs 迁移的影响。通过柱实验考察了这些因素对 FHNPs 迁移的影响。农业有机输入物释放的溶解性有机质（DOM）（0.008-24.8 mg/L）将 FHNPs 的 zeta 电位从 30.8 mV 降低到 14.6-48.9 mV，进一步导致 FHNPs 和混合砂之间产生静电排斥、渗透排斥和弹性-位阻排斥，从而增强了 FHNPs 的迁移。由于 DOM 含量的增加，生物炭和猪粪的含量增加导致 FHNPs 迁移增加。然而，由于有机输入物的存在，表面粗糙度在一定程度上（比表面积增加高达 4.6 m）成为影响 FHNPs 迁移的主要抑制因素。DOM 释放后，农业有机输入物降低了 FHNPs 迁移的增强作用；随着输入物的增加，其更粗糙的表面逐渐增加了对 FHNPs 迁移的抑制作用。在碱热生物炭（0.2-10%）或猪粪（1-2%）混合砂柱中 FHNPs 的保留率最强，表明完全老化的农业有机输入物强烈抑制了 FHNPs 的迁移。本研究结果为农业有机输入物及其老化对 FHNPs 迁移的关键影响提供了新的认识，这种影响逐渐由增强转变为抑制。
