Pesticide monitoring and ecotoxicological risk assessment in surface water bodies and sediments of a tropical agro-ecosystem.

Unlabelled: A pesticide monitoring study including 80 and 60 active ingredients (in surface waters and sediments, respectively) was carried out in a river basin in Costa Rica during 2007-2012. A special emphasis was given on the exceptional ecological conditions of the tropical agro-ecosystem and the pesticide application strategies in order to establish a reliable monitoring network. A total of 135 water samples and 129 sediment samples were collected and analyzed.

Expanding the application scope of on-farm biopurification systems: Effect and removal of oxytetracycline in a biomixture.

Antibiotic-containing wastewaters produced in agricultural activities may depress the pesticide-degrading capacity of biomixtures contained in biopurification systems. This work aimed to assay the effect of oxytetracycline (OTC) on the removal of carbofuran (CFN) in an optimized biomixture, and to determine the capacity of the system to dissipate OTC. During co-application of CFN+OTC, CFN removal and its accelerated degradation were not negatively affected.

Simultaneous removal of structurally different pesticides in a biomixture: Detoxification and effect of oxytetracycline.

The biopurification systems (BPS) used for the treatment of pesticide-containing wastewater must present a versatile degrading ability, in order to remove different active ingredients according to the crop protection programs. This work aimed to assay the simultaneous removal of several pesticides (combinations of herbicides/insecticides/fungicides, or insecticides/fungicides) in a biomixture used in a BPS over a period of 115 d, and in the presence of oxytetracycline (OTC), an antibiotic of agricultural use that could be present in wastewater from agricultural pesticide application practices. The biomixture was able to mostly remove the herbicides during the treatment (removal rates: atrazine ≈ linuron > ametryn), and suffered no inhibition by OTC (only slightly for ametryn).

Removal of carbamates and detoxification potential in a biomixture: Fungal bioaugmentation versus traditional use.

The use of fungal bioaugmentation represents a promising way to improve the performance of biomixtures for the elimination of pesticides. The ligninolyitc fungus Trametes versicolor was employed for the removal of three carbamates (aldicarb, ALD; methomyl, MTM; and methiocarb, MTC) in defined liquid medium; in this matrix ALD and MTM showed similar half-lives (14d), nonetheless MTC exhibited a faster removal, with a half-life of 6.5d.

Effects of oxytetracycline on the performance and activity of biomixtures: Removal of herbicides and mineralization of chlorpyrifos.

Biopurification systems (BPS) are design to remove pesticides from agricultural wastewater. This work assays for the first time the potential effect of an antibiotic of agricultural use (oxytetracycline, OTC) on the performance of a biomixture (biologically active core of BPS), considering that antibiotic-containing wastewaters are also produced in agricultural labors. The respiration of the biomixture was stimulated in the presence of increasing doses of OTC (≥100mgkg), and only slightly increased with lower doses (≤10mgkg).

Removal of carbofuran is not affected by co-application of chlorpyrifos in a coconut fiber/compost based biomixture after aging or pre-exposure.

Biomixtures constitute the biologically active part of biopurification systems (BPS), which are used to treat pesticide-containing wastewater. The aim of this work was to determine whether co-application of chlorpyrifos (CLP) affects the removal of carbofuran (CFN) (both insecticide/nematicides) in a coconut fiber-compost-soil biomixture (FCS biomixture), after aging or previous exposure to CFN. Removal of CFN and two of its transformation products (3-hydroxycarbofuran and 3-ketocarbofuran) was enhanced in pre-exposed biomixtures in comparison to aged biomixtures.

Design of an optimized biomixture for the degradation of carbofuran based on pesticide removal and toxicity reduction of the matrix.

Pesticide biopurification systems contain a biologically active matrix (biomixture) responsible for the accelerated elimination of pesticides in wastewaters derived from pest control in crop fields. Biomixtures have been typically prepared using the volumetric composition 50:25:25 (lignocellulosic substrate/humic component/soil); nonetheless, formal composition optimization has not been performed so far. Carbofuran is an insecticide/nematicide of high toxicity widely employed in developing countries.

Adaptation of biomixtures for carbofuran degradation in on-farm biopurification systems in tropical regions.

A biomixture constitutes the active core of the on-farm biopurification systems, employed for the detoxification of pesticide-containing wastewaters. As biomixtures should be prepared considering the available local materials, the present work aimed to evaluate the performance of ten different biomixtures elaborated with by-products from local farming, in the degradation of the insecticide/nematicide carbofuran (CFN), in order to identify suitable autochthonous biomixtures to be used in the tropics. Five different lignocellulosic materials mixed with either compost or peat and soil were employed in the preparation of the biomixtures.

Accelerated biodegradation of selected nematicides in tropical crop soils from Costa Rica.

Degradation and mineralization behavior of selected nematicides was studied in soil samples from fields cultivated with banana, potato, and coffee. Degradation assays in most of the studied soils revealed shorter half-lives for carbofuran (CBF) and ethoprophos (ETP) in samples with a history of treatment with these compounds, which may have been caused by enhanced biodegradation. A short half-life value for CBF degradation was also observed in a banana field with no previous exposure to this pesticide, but with a recent application of the carbamate insecticide oxamyl, which supports the hypothesis that preexposure to oxamyl may cause microbial adaptation towards degradation of CBF, an observation of a phenomenon not yet tested according to the literature reviewed.

On-farm biopurification systems: role of white rot fungi in depuration of pesticide-containing wastewaters.

Environmental contamination with pesticides is an undesired consequence of agricultural activities. Biopurification systems (BPS) comprise a novel strategy to degrade pesticides from contaminated wastewaters, consisting of a highly active biological mixture confined in a container or excavation. The design of BPS promotes microbial activity, in particular by white rot fungi (WRF).