Pesticides are used worldwide with potential harmful effects on both fauna and flora. The Kibale National Park in Uganda, a site renowned for its biodiversity is surrounded by tea, banana and eucalyptus plantations as well as maize fields and small farms. We previously showed presence of pesticides with potential endocrine disruptive effects in the vicinity. To further investigate the water pollution linked to agricultural pressure in this protected area, we implemented a complementary monitoring strategy based on: analytical chemistry, effects based methods and the deployment of Polar Organic Chemical Integrative Samplers (POCIS). Chemical analysis of the POCIS extracts revealed the presence of 13 pesticides: carbofuran, DEET, 2.4-D amine, carbaryl, ametryn, isoproturon, metolachlor, terbutryn, dimethoate, imidacloprid, picaridin, thiamethoxam, carbendazim, with the first three being present in the largest quantities. Water samples collected at the POCIS sampling sites exhibited thyroid and estrogen axis disrupting activities in vivo, in addition to developmental and behaviour effects on Xenopus laevis tadpoles model. Based on our observations, for the health of local human and wildlife populations, further monitoring as well as actions to reduce agrochemical use should be considered in the Kibale National Park and in regions exposed to similar conditions.

This study investigated the ability of natural river biofilms from different seasons to degrade the carbamate pesticides methomyl, carbaryl and carbofuran in single and multiple pesticide systems, and the effects of these pesticides on algal and bacterial communities within biofilms. Spring biofilms had the lowest biomass of algae and bacteria but showed the highest methomyl degradation (>99%) and dissipation rates, suggesting that they might contain microorganisms with high methomyl degradation abilities. Degradation of carbofuran (54.1–59.5%) by biofilms in four seasons was similar, but low degradation of carbaryl (0–27.5%) was observed. The coexistence of other pesticides was found to cause certain effects on pesticide degradation and primarily resulted in lower diversity of diatoms and bacteria than when using a single pesticide. The tolerant diatoms and bacteria potentially having the ability to degrade test pesticides were identified. River biofilms could be suitable biomaterials or used to isolate degraders for bioremediating pesticide-contaminated water.

Polyethylene (PE) and polypropylene (PP) microplastics (MPs), as carriers, can bind with pesticides, which propose harmful impacts to aqueous ecosystems. Meanwhile, carbofuran and carbendazim (CBD), two widely used carbamate pesticides, are toxic to humans because of the inhibition of acetylcholinesterase activity. The interaction between two MPs and two pesticides could start in farmland and be maintained during transportation to the ocean. Herein, the adsorption behavior and mechanism of carbofuran and carbendazim (CBD) by PE and PP MPs were investigated via characterization and density functional theory (DFT) simulation. The adsorption kinetic and thermodynamic data were best described by pseudo-second-order kinetics and the Freundlich models. The adsorption behaviors of individual carbofuran/CBD on both MPs were very similar. The CBD adsorption rate and capacity of PE and PP MPs were higher than those of carbofuran. This phenomenon explained the lower negative effects of DOM (oxalic acid, glycine (Gly)) on CBD adsorption relative to those of carbofuran. The presence of oxalic acid and Gly decreased the PE adsorption by 20.40–48.02% and the PP adsorption by 19.27–42.11%, respectively. It indicated the significance of DOM in carbofuran cycling. The adsorption capacities were negatively correlated with MPs size, indicating the importance of specific surficial area. Fourier transformation infrared spectroscopy before and after adsorption suggested that the adsorption process did not produce any new covalent bond. Instead, intermolecular van der Waals forces were one of the primary adsorption mechanisms of carbofuran and CBD by MPs, as evidenced by DFT calculations. Based on the zeta potential, the electrostatic interaction explained the higher adsorption CBD by MPs than carbofuran.

Understanding the processes that regulate contaminant impacts in nature is an increasingly important challenge. For insecticides in surface waters, the ability of aquatic plants to sorb, or bind, hydrophobic compounds has been identified as a primary mechanism by which toxicity can be mitigated (i.e. the sorption-based model). However, recent research shows that submerged plants can also rapidly mitigate the toxicity of the less hydrophobic insecticide malathion via alkaline hydrolysis (i.e. the hydrolysis-based model) driven by increased water pH resulting from photosynthesis. However, it is still unknown how generalizable these mitigation mechanisms are across the wide variety of insecticides applied today, and whether any general rules can be ascertained about which types of chemicals may be mitigated by each mechanism. We quantified the degree to which the submerged plant Elodea canadensis mitigated acute (48-h) toxicity to Daphnia magna using nine commonly applied insecticides spanning three chemical classes (carbamates: aldicarb, carbaryl, carbofuran; organophosphates: malathion, diazinon, chlorpyrifos; pyrethroids: permethrin, bifenthrin, lambda-cyhalothrin). We found that insecticides possessing either high octanol-water partition coefficients (log Kow) values (i.e. pyrethroids) or high susceptibility to alkaline hydrolysis (i.e. carbamates and malathion) were all mitigated to some degree by E. canadensis, while the plant had no effect on insecticides possessing intermediate log Kow values and low susceptibility to hydrolysis (i.e. chlorpyrifos and diazinon). Our results provide the first general insights into which types of insecticides are likely to be mitigated by different mechanisms based on known chemical properties. We suggest that current models and mitigation strategies would be improved by the consideration of both mitigation models.

Among the most frequent targets for toxic effects of modern pesticides, namely organophosphates and carbamates, one may find cholinesterases (ChEs). ChEs exist in a wide variety of animals and have been used actively to discriminate among the environmental effects of different pollutant groups, including the aforementioned pesticides. This study had three purposes, namely (i) identifying the ChE forms present in tissues (eyes and walking legs muscle) of two crab species, Carcinus maenas and Pachygrapsus marmoratus; to (ii) determine the in vitro toxicological effects, and (iii) compare the sensitivity of such enzymatic forms towards commonly used anti-ChE pesticides, namely the organophosphate chlorpyrifos and the carbamate carbofuran. Our results showed that there was not a clear preference for any of the tested substrates in any of the tissues from both species. Furthermore, the ChE activity was almost completely suppressed following incubation with eserine and with the specific inhibitor BW284C51 in all tissues from both species. In vitro exposure to chlorpyrifos promoted a significant decrease in ChE activity in both species. Furthermore, the ChE activity was completely suppressed following incubation with carbofuran and chlorpyrifos. These results suggest that the major ChE forms present in tissues of both crab species show intermediate structural properties and activity patterns, halfway between classic acetylcholinesterase and pseudocholinesterases. However, the sensitivity of the found forms towards ChE inhibitors was established, and the responsiveness of such forms towards common anti-ChE chemicals was established. Both tested species seem to be promising test organisms to be used in marine and coastal scenarios of putative contaminations by anti-ChE chemicals, considering the here reported patterns of response.

One of the major causes of aquatic biodiversity loss is the contamination of the environment by pesticides. Even though there is a considerable amount of studies on the subject, there are still few that deal with the effects of carbofuran on native species in Brazil. Although carbofuran is widely used in Brazil, its action on native organisms, such as the Atlantic Forest lambari Deuterodon iguape, has not yet been studied. This work aimed to evaluate the effects of exposure to carbofuran on the fish D. iguape, considering the behavior and specific oxygen consumption as end points. Opercular movements, dorsal fin movements, and swimming speed were analyzed as behavioral parameters. To assess specific oxygen consumption, fish were subjected to concentrations of 0.0, 0.05, 0.1, 0.25, and 0.5 mg/L, for 24 h. For behavior analysis, fish remained exposed to carbofuran at concentrations of 0.0, 0.01, 0.05, 0.1, and 0.5 mg/L, in periods of 0, 2, 24, and 48 h. The behavior was studied through filming, analyzed with the free software, Tracker 4.92 (Open Source Physics). The results demonstrate an increase in opercular movements (18% ± 2.65) and a decrease in dorsal fin movements (− 21.2% ± 2.97), as well as in swimming speed (− 58.3% ± 1.83) of the experimental groups compared to the control group. There was an increase in oxygen consumption of 58.4% in fish exposed to the highest concentration of carbofuran. Thus, it is concluded that carbofuran altered D. iguape’s behavior and oxygen consumption. The species was sensitive to carbofuran concentrations and can be used as a bioindicator.

Biopurification systems (BPS) are employed for the treatment of pesticide-containing wastewaters. In this work, a biomixture (active core of BPS) complemented by the addition of the fungus Trametes versicolor was evaluated for the elimination of a mixture of pesticides under different treatment conditions. The biomixture achieved high removal of all the pesticides assayed after 16 d: atrazine (68.4%, t₁/₂: 9.6 d), carbendazim (96.7%, t₁/₂: 3.6 d), carbofuran (98.7%, t₁/₂: 3.1 d) and metalaxyl (96.7%, t₁/₂: 3.8 d). Variations in the treatment conditions including addition of the antibiotic oxytetracycline and co-bioaugmentation with a bacterial consortium did not significantly affect the removal performance of the biomixture. Bacterial and fungal community profiles determined by DGGE analyses revealed changes that responded to biomixture aging, and not to antibiotic or pesticide addition. The proposed biomixture exhibits very efficient elimination during simultaneous pesticide application; moreover, the matrix is highly stable during stressful conditions such as the co-application of antibiotics of agricultural use.

This study proposed the optimization of a laccase-mediator system to reduce pesticide levels (bentazone, carbofuran, diuron, clomazone, tebuconazole, and pyraclostrobin) on aqueous medium. Firstly, the mediator concentration of 1 mM was established (average removal of 36%). After that, seven redox-mediating compounds, namely, 2,20-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, caffeic acid, chlorogenic acid, p-coumaric acid, ferulic acid, gallic acid, protocatechuic acid, and vanillin, were compared regarding their removal efficiency. The highest removal (77%) was achieved with the laccase-vanillin system. After this screening, the optimization was carried out by a 2² full factorial design. Variables under study were the enzyme (laccase) activity and vanillin concentration. Maximum removal (53–85%) was achieved with 0.95 U/mL laccase and 1.8 mM vanillin. Pesticide removal in reaction media was fitted to the first-order kinetics equation with an average half-time life of 2.2 h. This is the first study of the use of this natural compound as a mediator in the degradation of the pesticides under investigation. The results of this study contribute, with alternative methods, to decrease pesticide levels since they are highly persistent in aqueous samples and, as a result, mitigate the environmental impact.

A monitoring study was carried out in two micro-catchments in the Reventazón basin, in Northern Cartago, Costa Rica; pesticide occurrence and water quality were analyzed. Twelve pesticides were detected, five insecticides (chlorpyrifos, carbofuran, cypermethrin, imidacloprid, and oxamyl), four fungicides (carbendazim, imazalil, metalaxyl, and thiabendazole), and three herbicides (diuron, linuron, and terbutryn); eight of them presented risk quotients RQ >1, which implies a high risk for the environment. The water quality evaluation included fourteen physicochemical and microbiological parameters, out of which thermotolerant coliforms, nitrate, and total phosphorus exceeded a selected threshold value in every sample. Five metals were also included in the evaluation, Pb was the most frequent, followed by few detections of Cd, Cu, and Cr. Four water quality indexes (WQIs) were applied, two of them, the CCME WQI, based on physicochemical parameters, and the BMWP-CR WQI, based on benthic macroinvertebrate recount adapted to Costa Rican species, categorized all the sampling points as “bad” and “very bad” quality. This work of monitoring is important in the Latin American region, where there is a lack of information for regulation improvement and management decisions. These results showed poor management of the micro-catchments in this agricultural rural area.

In this study, a multi-residue method was used to analyze 13 pesticides and 1 degradation product in surface and groundwater in the region with the largest sugar cane production in the world. The potential effects of individual pesticides and their mixtures, for aquatic life and human consumption, were evaluated. For the surface water, 2-hydroxy atrazine, diuron, carbendazim, tebuthiuron, and hexazinone were the most frequently detected (100, 94, 93, 92, and 91%, respectively). Imidacloprid (2579 ng L⁻¹), carbendazim (1114 ng L⁻¹), ametryn (1101 ng L⁻¹), and tebuthiuron (1080 ng L⁻¹) were found at the highest concentrations. For groundwater, tebuthiuron was the only quantified pesticide (107 ng L⁻¹). Ametryn, atrazine, diuron, hexazinone, carbofuran, imidacloprid, malathion, carbendazim, and their mixtures presented risk for the aquatic life. No risk was observed for the pesticides analyzed in this work, alone or in their mixtures for human consumption.