Leaching behaviour appraisal of eight persistent herbicides on a loam soil amended with different composted organic wastes using screening indices

Sensitivity and antioxidant response of forest species seedlings to the atrazine under simulated conditions of subsurface water contamination

Atrazine is an herbicide with a high soil leaching capacity, contaminating subsurface water sources. Once the water table is contaminated, riparian species can be exposed to atrazine. In this way, understanding the impacts of this exposure must be evaluated for planning strategies that minimize the effects of this herbicide on native forest species. We aimed to evaluate forest species' sensitivity and antioxidant response to exposure to subsurface waters contaminated with atrazine, as well the dissipation this herbicide. The experiment was conducted in a greenhouse in a completely randomized design, with three replications and one plant per experimental unit. The treatments were arranged in a 2 × 10 factorial. The first factor corresponded to the presence or absence (control) of the atrazine in the subsurface water. The second factor comprised 10 forest species: Amburana cearensis, Anadenanthera macrocarpa, Bauhinia cheilantha, Enterolobium contortisiliquum, Hymenaea courbaril, Libidibia ferrea, Mimosa caesalpiniifolia, Mimosa tenuiflora, Myracrodruon urundeuva, and Tabebuia aurea. The forest species studied showed different sensitivity levels to atrazine in subsurface water. A. cearensis and B. cheilantha species do not have efficient antioxidant systems to prevent severe oxidative damage. The species A. macrocarpa, E. contortisiliquum, L. ferrea, and M. caesalpiniifolia are moderately affected by atrazine. H. courbaril, M. urundeuva, and T. aurea showed greater tolerance to atrazine due to the action of the antioxidant system of these species, avoiding membrane degradation events linked to the production of reactive oxygen species (ROS). Among the forest species, H. courbaril has the most significant remedial potential due to its greater tolerance and reduced atrazine concentrations in the soil.

Study of the degradation of diphenyl-ether herbicides aclonifen and bifenox in different environmental waters

The degradation of the diphenyl-ether herbicides aclonifen (ACL) and bifenox (BF) in water samples has been studied under different laboratory conditions, using in-tube solid-phase microextraction (IT-SPME) coupled to capillary liquid chromatography (capLC). The working conditions were selected in order to detect also bifenox acid (BFA), a compound formed as a result of the hydroxylation of BF. Samples (4 mL) were processed without any previous treatment, which allowed the detection of the herbicides at low ppt levels. The effects of temperature, light and pH on the degradation of ACL and BF have been tested using standard solutions prepared in nanopure water. The effect of the sample matrix has been evaluated by analysing different environmental waters spiked with the herbicides, namely ditch water, river water and seawater. The kinetics of the degradation have been studied and the half-life times (t_1/2) have been calculated. The results obtained have demonstrated that the sample matrix is the most important parameter affecting the degradation of the tested herbicides. The degradation of both ACL and BF was much faster in ditch and river water samples, where t_1/2 values of only a few days were observed. However, both compounds showed a better stability in seawater samples, where they can persist for several months. In all matrices ACL was found to be more stable than BF. In samples where BF had been substantially degraded, BFA was also detected, although the stability of this compound was also limited. Other degradation products have been detected along the study.

Water vulnerability to pesticide contamination in a Brazilian semiarid watershed

This study aimed to prepare an inventory of the main active ingredients of pesticides and estimate the risk of pollution of groundwater and surface water resources in a Brazilian semiarid basin. The inventory was prepared using data from government agency databases. The contamination risk estimate was obtained using the GOSS index, Groundwater Ubiquity Score (GUS), Groundwater Screening Index (GSI), Leachability Index (LIX), US Environmental Protection Agency (USEPA) criteria, Leaching Index (LEACH), and Relative Leaching Potential Index (RLPI). The inventory identified 57 active ingredients commercialized under a well-defined chemical class. Most of these (51.5%) belong to the very dangerous class, while 43.6% belong to the moderately toxic class. The GOSS model showed that 23.7% of the active ingredients have a low potential, 50.85% have a moderate potential, and 13.56% have a high potential for surface water contamination, with its transport being associated with the sediment. The GUS index indicates a low potential for groundwater contamination. However, the GSI points to a high potential for water contamination, the USEPA criteria for a possible contamination of groundwater, and, according to the LIX, most of the pollutants do so by leaching. The information provided contributes to the management of xenobiotic compounds in arid and semiarid basins, adding to the water security effort by providing tools for the assessment of potential pesticide pollution. Integr Environ Assess Manag 2023;19:804-816. © 2022 SETAC.

Connecting the evidence about organic pollutant sorption on soils with environmental regulation and decision-making: A scoping review

There exists an increase of review articles of pollutant sorption on soils due to the relevance of this process in environmental fate. However, this information is not used to make environmental decisions. We conduct a scoping review to identify and categorize the state-of-the-art of pesticide sorption (organic pollutant model) and decision-making studies in 2015-2020 using databases (Web of Science, Scopus and ScieLo) to detect potential gaps and create a framework that guide the connection between scientific evidence and its institutionalization. We detect research gaps (inside sorption or decision-making studies) and evidence gaps (between sorption and decision-making) from literature based on five categories to describe sorption (sorbate-sorbent system, system variables to study the sorption process, objectives pursued by authors, experimental approaches to study the sorption process, and quantification of sorption) and four topics for regulatory contexts (sponsor contextualization, descriptive information, environmentally relevant issues and Sustainable Development Goals (SDGs)). The gaps included (i) unrelated study designs, (ii) unreliable causal mechanisms, (iii) unrelated SDGs, (iv) lack of collaboration, (v) lack of representativeness, (vi) lack of knowledge, (vii) lack of relevant studies, and (vii) unknown causal extrapolation. Our framework connected the gaps with relevant environmental issues and common research topics on sorption studies, including suggested solutions and inclusion of lacking SDG in literature. The framework can assist the science-policy interaction, promoting cooperation for different study designs, pollutant-soil systems, and socio-environmental applications, such as environmental fate and management, risk assessment, monitoring, remediation, and local regulations.

Aclonifen could induce implantation failure during early embryonic development through apoptosis of porcine trophectoderm and uterine luminal epithelial cells

Aclonifen is a diphenyl-ether herbicide that is used to control the growth of weeds while growing crops such as corn and wheat. Although the biochemical effects of aclonifen are well characterized, including its ability to inhibit protoporphyrinogen oxidase and carotenoid synthesis, the toxicity of aclonifen in embryonic implantation and development during early pregnancy, has not been reported. Thus, in this study, we investigated the potential interference of aclonifen in embryonic implantation using porcine trophectoderm (pTr) and uterine luminal epithelial (pLE) cells isolated during implantation period of early pregnancy. Cell viability in both pTr and pLE cells significantly decreased in a dose-dependent manner following aclonifen treatment. Moreover, the proportion of cells in the sub-G1 phase of the cell cycle gradually increased upon treatment with increasing concentrations of aclonifen, which in turn led to an increase in the number of apoptotic cells, as determined by annexin V and propidium iodide staining. Aclonifen treatment caused mitochondrial dysfunction by increasing the depolarization of the mitochondrial membrane potential and the mitochondrial calcium concentration. Aclonifen inhibited cell mobility by suppressing the expression of implantation-related genes in pTr and pLE cells. To explore the underlying mechanism, we evaluated the phosphorylation of PI3K and MAPK signaling molecules. The phosphorylation of AKT, S6, JNK, and ERK1/2 were significantly increased by aclonifen. Collectively, our results suggest that aclonifen may interrupt implantation during early pregnancy by disrupting maternal-fetal interaction.

Effects of the presence of triclocarban on the degradation and migration of co-occurring pesticides in soil

Triclocarban (TCC), a bactericide widely used in personal care products, is frequently detected in soil and surface water, which may affect the environmental behavior of other environmental pollutants by changing the community structure of environmental microorganisms. This work evaluated the effects of TCC on the degradation and migration of seven herbicides and five fungicides in soil under co-occurrence conditions. TCC significantly increased the persistence of the pesticides in soil, and this effect increased with TCC concentration. For example, the half-life of metolachlor, atrazine, metribuzin, and metamitron increased 44%, 38%, 153%, and 33%, respectively, with 10 mg/kg TCC and increased 60%-640% with 100 mg/kg TCC. After 90 days, the residue of the pesticides in soil treated with TCC was significantly elevated relative to the control. TCC treatment could also increase the potential leaching risk of the herbicides in the soil, as indicated by an increased Groundwater Ubiquity Score (GUS) index. The reduced abundance of soil bacteria by TCC might be an essential reason for the impacts on the environmental behavior of the pesticides. This study confirmed that TCC could slow down the degradation of pesticides in soil, increase their persistence and even affect the leaching behavior, thus influencing the risks of the pesticides to the environment.

Application of an Adsorption Process on Selected Materials, Including Waste, as a Barrier to the Pesticide Penetration into the Environment

The article presents research on using the adsorption process of aldrin (a chloro-organic pesticide that most often occurs in the environment near expired pesticide burials). The research used three sorbents: two activated carbons and compost from sewage sludge as a low-cost sorbent. Obtained adsorption isotherms belong to the L group according to the Giles classification. The test results and their analysis confirm that the IZO application facilitates the analysis of the adsorption process. The study results also confirm that compost can be a cost-effective alternative to commercial activated carbons to build barriers protecting the environment against existing leaking expired pesticide burials.

Interaction between herbicides applied in mixtures alters the conception of its environmental impact

Herbicide mixtures have often been used to control weeds in crops worldwide, but the behavior of these mixtures in the environment is still poorly understood. Laboratory and greenhouse tests have been conducted to study the interaction of the herbicides diuron, hexazinone, and sulfometuron-methyl which have been applied alone and in binary and ternary mixtures in the processes of sorption, desorption, half-life, and leaching in the soil. A new index of the risk of leaching of these herbicides has also been proposed. The sorption and desorption study has been carried out by the batch equilibrium method. The dissipation of the herbicides has been evaluated for 180 days to determine the half-life (t_1/2). The leaching tests have been carried out on soil columns. The herbicides isolated and in mixtures have been quantified using ultra-high performance liquid chromatography coupled to the mass spectrometer. Diuron, hexazinone, and sulfometuron-methyl in binary and ternary mixtures have less sorption capacity and greater desorption when compared to these isolated herbicides. Dissipation of diuron alone is slower, with a half-life (t_1/2) = 101 days compared to mixtures (t_1/2 between 44 and 66 days). For hexazinone and sulfometuron-methyl, the dissipation rate is lower in mixtures (t_1/2 over 26 and 16 days), with a more pronounced effect in mixtures with the presence of diuron (t_1/2 = 47 and 56 and 17 and 22 days). The binary and ternary mixtures of diuron, hexazinone, and sulfometuron-methyl promoted more significant transport in depth (with the three herbicides quantified to depth P4, P7, and P7, respectively) compared to the application of these isolated herbicides (quantified to depth P2, P4, and P5). Considering the herbicides' desorption and solubility, the new index proposed to estimate the leaching potential allowed a more rigorous assessment concerning the risk of leaching these pesticides, with hexazinone and sulfometuron-methyl presenting a higher risk of contamination of groundwater.

Removal Kinetics of Four Leacher Herbicides Through Solar Heterogeneous Photocatalysis as Influenced by Water Matrix Components

This work focuses on the effect of dissolved substances on the photocatalytic degradation of four herbicides, metribuzin and terbuthylazine (triazine) and chlorotoluron and isoproturon (phenylurea) in three different water matrix (deionized, mineral and leaching water). To study the effect of heterogeneous photocatalysis on their degradation, TiO₂ and ZnO were used as photocatalysts in tandem with an oxidant (Na₂S₂O₈). Results show that the addition of both semiconductor materials significantly enhances degradation of the herbicides although in different proportions. Similar effectivity of both photocatalyst, assessed as a function of the mean half-lives calculated, was observed (85 and 87 min for TiO₂ and Zn, respectively), while the mean half-life in the photolytic experiment was markedly higher (265 min). The degradation rate was in the order: metribuzin > chlorotoluron ≈ isoproturon > terbuthylazine. A faster degradation was observed in all cases in deionized water as compared to mineral and leaching water indicating that the presence of dissolved salts and organic matter considerably slows down the effectiveness of the treatment. Although after 180 min of treatment, total mineralization was not achieved in mineral and leaching water, this technology considerably reduces the pollutant load in complex water matrices. Therefore, solar heterogeneous photocatalytic processes, especially those involving ZnO and TiO₂ as photocatalysts, offers a valuable tool for surface and groundwater remediation, especially in those areas receiving a large number of hours of sunshine per year.