Ukalska-Jaruga Aleksandra, Bejger Romualda, Smreczak Bożena, Weber Jerzy, Mielnik Lilla, Jerzykiewicz Maria, Ćwieląg-Piasecka Irmina, Jamroz Elżbieta, Debicka Magdalena, Kocowicz Andrzej, Bekier Jakub
Department of Soil Science Erosion and Land Protection, Institute of Soil Science and Plant Cultivation-State Research Institute, Czartoryskich 8, 24-100 Puławy, Poland.
Department of Bioengineering, West Pomeranian University of Technology in Szczecin, Papieża Pawła VI/3, 71-459 Szczecin, Poland.
Molecules. 2023 Oct 18;28(20):7146. doi: 10.3390/molecules28207146.
The constant influx of pesticides into soils is a key environmental issue in terms of their potential retention in the soil, thus reducing their negative impact on the environment. Soil organic matter (SOM) is an important factor influencing the environmental fate of these substances. Therefore, the aim of this research was to assess the chemical behavior of pesticides (flufenacet, pendimethalin, α-cypermethrin, metazachlor, acetamiprid) toward stable soil humin fractions (HNs) as a main factor affecting the formation of non-extractable residues of agrochemicals in soil. This research was conducted as a batch experiment according to OECD Guideline 106. For this purpose, HNs were isolated from eight soils with different physicochemical properties (clay content = 16-47%, pH = 5.6-7.7, TOC = 13.3-49.7 g·kg, TN = 1.06-2.90 g·kg, TOC/TN = 11.4-13.7) to reflect the various processes of their formation. The extraction was carried out through the sequential separation of humic acids with 0.1 M NaOH, and then the digestion of the remaining mineral fraction with 10% HF/HCl. The pesticide concentrations were detected using GC-MS/MS. The pesticides were characterized based on the different sorption rates to HNs, according to the overall trend: metazachlor (95% of absorbed compound) > acetamiprid (94% of absorbed compound) > cypermethrin (63% of partitioning compound) > flufenacet (39% of partitioning compound) > pendimethalin (28% of partitioning compound). Cypermethrin and metazachlor exhibited the highest saturation dynamic, while the other agrochemicals were much more slowly attracted by the HNs. The obtained sorption kinetic data were congruous to the pseudo-first-order and pseudo-second-order models related to the surface adsorption and interparticle diffusion isotherm. The conducted research showed that the processes of pesticide sorption, apart from physicochemical phenomena, are also affected by the properties of the pollutants themselves (polarity, K) and the soil properties (SOM content, clay content, and pH).
农药不断流入土壤是一个关键的环境问题，因为它们有可能滞留在土壤中，从而减少其对环境的负面影响。土壤有机质（SOM）是影响这些物质环境归宿的一个重要因素。因此，本研究的目的是评估农药（氟噻草胺、二甲戊灵、高效氯氰菊酯、异丙甲草胺、啶虫脒）对稳定土壤胡敏素组分（HNs）的化学行为，HNs是影响土壤中农药不可提取残留形成的主要因素。本研究按照经合组织准则106进行批量实验。为此，从八种具有不同理化性质（粘土含量 = 16 - 47%，pH = 5.6 - 至7.7，TOC = 13.3 - 49.7 g·kg，TN = 1.06 - 2.90 g·kg，TOC/TN = 11.4 - 13.7）的土壤中分离出HNs，以反映其形成的各种过程。通过用0.1 M NaOH顺序分离腐殖酸，然后用10% HF/HCl消化剩余的矿物部分来进行提取。使用GC - MS/MS检测农药浓度。根据总体趋势，根据农药对HNs的不同吸附率对农药进行了表征：异丙甲草胺（95%的吸收化合物）>啶虫脒（94%的吸收化合物）>氯氰菊酯（63%的分配化合物）>氟噻草胺（39%的分配化合物）>二甲戊灵（28%的分配化合物）。氯氰菊酯和异丙甲草胺表现出最高的饱和动力学，而其他农用化学品被HNs吸引的速度要慢得多。获得的吸附动力学数据与与表面吸附和颗粒间扩散等温线相关的准一级和准二级模型一致。所进行的研究表明，农药吸附过程除了物理化学现象外，还受到污染物本身的性质（极性、K）和土壤性质（SOM含量、粘土含量和pH）的影响。
