Removal of Two Neonicotinoid Insecticides and Mineralization of 14C-Imidacloprid in Biomixtures

Abstract

Environmental contamination with neonicotinoid insecticides represents an issue of wide concern due to their negative effects on pollinators. The goal of this work was to evaluate the potential use of biomixtures employed in biopurification systems (BPS) to remove two neonicotinoid pesticides, imidacloprid and thiamethoxam, from wastewater of agricultural origin. The removal was assayed by quantification of the parent compounds and the detection of putative transformation products of imidacloprid by means of LC-MS/MS, and mineralization of radiolabeled imidacloprid. Two biomixtures (B1, B2) were prepared using coconut fiber, compost and two soils pre-exposed to imidacloprid (volumetric composition 50:25:25). After spiking of neonicotinoids and 228 days of treatment, the removal ranged from 22.3%-30.3% and 38.6%-43.7% for imidacloprid and thiamethoxam, respectively. Transformation products imidacloprid-urea, desnitro-imidacloprid and desnitro-olefin-imidacloprid were detected in both biomixtures. The mineralization of C-imidacloprid revealed DT50 (mineralization half-lives) values of 3466 and 7702 days in the biomixtures B1 and B2, respectively, markedly lower than those in the soil used in their preparation (8667 and 9902 days, respectively). As demonstrated by these findings, the high persistence of these compounds in the BPS suggests that additional biological (or physicochemical) approaches should be explored in order to decrease the impact of neonicotinoid-containing wastewater of agricultural origin.

Destination of pesticide residues on biobeds: State of the art and future perspectives in Latin America

“…In Costa Rica, researchers are testing biobeds with a modified biomixture whose degradation efficiency was evaluated through chemical analysis and ecotoxicity tests, for chlorpyrifos, carbofuran, imidacloprid, thiamethoxam and other pesticides. That biomixture was composed of coconut fiber, composted vegetal residues and soil (Chin-Pampillo et al, 2016;Rodríguez-Castillo et al, 2018). In Mexico, G ongora-Echeverría et al ( 2018) evaluated sisal pulp, composted vegetal residue, corn husk and seaweed.…”

On-Farm Removal of Pesticides: Current Insights on Biopurification Systems

“…As in the case of triazoles, the assessment of neonicotinoids has also revealed cases of removal failure in BPSs, as reported for imidacloprid and thiamethoxam; mineralization of the former has even shown DT 50 values over 3466 d, clearly making the process infeasible for real conditions . Conversely, some works have achieved enhanced elimination of imidacloprid , or acetamiprid .…”

“…Faster or slower elimination compared to soil was reported for ten triazoles at low concentrations during the treatment of complex wastewater of laboratory origin, achieving an overall removal of 73.4% of total triazole concentration after 281 d. 19 As in the case of triazoles, the assessment of neonicotinoids has also revealed cases of removal failure in BPSs, as reported for imidacloprid and thiamethoxam; 23 mineralization of the former has even shown DT 50 values over 3466 d, clearly making the process infeasible for real conditions. 34 Conversely, some works have achieved enhanced elimination of imidacloprid 32,35 or acetamiprid. 36 Summarizing, further research is still required to reach a more consistently successful elimination of certain groups, particularly triazoles or neonicotinoids; the definition of specialized biomixtures or the individual treatment of these pesticides (and not in pesticide mixtures) seems to be a key step in this regard.…”

Development of a model based on Support Vector Machines to predict the degradation of pesticides in biobeds systems

“…Additionally, mineralization studies using radiolabeled compounds and liquid scintillation techniques have investigated the complete oxidation of pesticides. Notably, radiotracer-based respirometry analysis stands out as a superior method, measuring the release of carbon dioxide (CO2) during pesticide degradation and providing valuable insights into the microbialfacilitated degradation rate (Rodríguez-Castillo et al, 2018;Ruiz-Hidalgo et al, 2014).…”