Citation: Caraba, M.N.; Roman, D.L.; Caraba, I.V.; Isvoran, A. Assessment of the Effects of the Herbicide Aclonifen and Its Soil Metabolites on Soil and Aquatic Environments. Agriculture 2023, 13, 1226. https:// doi.org/10.3390/agriculture13061226 Academic Editor: Cristina Abbate Received: 7 May 2023 Revised: 29 May 2023 Accepted: 8 June 2023 Published: 10 June 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). agriculture Article Assessment of the Effects of the Herbicide Aclonifen and Its Soil Metabolites on Soil and Aquatic Environments Marioara Nicoleta Caraba 1,2 , Diana Larisa Roman 1,2 , Ion Valeriu Caraba 3, * and Adriana Isvoran 1,2 1 Department Biology-Chemistry, Faculty of Chemistry-Biology-Geography, West University of Timisoara, Pestalozzi 16, 300315 Timisoara, Romania; marioara.filimon@e-uvt.ro (M.N.C.); diana.roman@e-uvt.ro (D.L.R.); adriana.isvoran@e-uvt.ro (A.I.) 2 Advanced Environmental Research Laboratories (AERL), Oituz 4, 300086 Timisoara, Romania 3 Faculty of Bioengineering of Animal Resources, University of Life Sciences “King Mihai I” from Timisoara, Calea Aradului 119, 300645 Timisoara, Romania * Correspondence: caraba_i@animalsci-tm.ro Abstract: Aclonifen is an herbicide with a global market that is expected to grow in the period 2021–2027. This study focuses on revealing the effects of both aclonifen and of its soil metabolites on aqueous and soil environments. The soil’s physicochemical parameters and activities of enzymes found in the soil (urease, dehydrogenase, catalase, alkaline phosphatase) were evaluated in laboratory conditions for soil treated with various doses of aclonifen (from half of a normal dose, 2.1 g/ha, to three times the normal dose) every 7 days for a period of 28 days. A computational approach was used to calculate the acute toxicity of aclonifen and of its soil metabolites on aqueous organisms and to evaluate the possible interactions of these compounds with soil enzymes. The results obtained in the experimental study showed a significant inhibitory effect of the herbicide aclonifen on the investigated enzymes; those activities were not recovered after 28 days in the presence of high doses of aclonifen. Statistically significant effects of the herbicide dose and exposure duration on enzymes’ activities were observed using post hoc analysis at the p < 0.001 level. Pearson’s correlations revealed that the investigated enzyme activities were usually strongly (p < 0.001) influenced by the organic matter, available phosphorus content, and nitrogen level. The outcomes of the computational study revealed moderate acute aqueous toxicity of aclonifen and of its metabolites. All metabolites were also able to bind to the investigated enzymes and may have an inhibitory effect on their activities. Keywords: enzymatic activity; molecular docking; aquatic toxicity 1. Introduction Pesticides are widely used in actual crop management to obtain more and cheaper food by protecting crops from pests and diseases. The global consumption of pesticides constantly grew in the last decade, arriving at approximately 2.7 million metric tons, meaning a 57% increase compared with that in 1990 [1]. Despite their beneficial effects regarding crop protection and agricultural efficiency, pesticides can affect the environment by leading to soil, water, and air pollution, may contaminate food, and may affect human health. Consequently, the evaluation of the potential risks of the use of pesticides for human health and ecological effects is one of the main concerns nowadays. Due to their effects on the environment, the use of pesticides is strongly regulated. The Environmental Protection Agency (EPA) in the United States (http://npic.orst.edu/ reg/laws.html---accessed on 24 May 2023) and the European Commission (https://food. ec.europa.eu/plants/pesticides---accessed on 24 May 2023) in the European Union have the authority to regulate pesticide use. Among the pesticides, the group of herbicides is the most used in food production and crop management [2]. The excessive use of herbicides usually leads to negative impacts on both the environment and human health [3]. In the soil, herbicides are degraded, being used Agriculture 2023, 13, 1226. https://doi.org/10.3390/agriculture13061226 https://www.mdpi.com/journal/agriculture