Simultaneous analysis of current-use pesticides and their transformation products in water using mixture-sorbent solid phase extraction and high-performance liquid chromatography-tandem mass spectrometry

Prediction of Potential Risk for Flupyradifurone and Its Transformation Products to Hydrobionts

Flupyradifurone (FPF) is considered the latest generation of neonicotinoid insecticides. Here, we investigated the toxicity and ecological risk of FPF and its aerobic transformation products (TPs) to aquatic species using the method of prediction. We found that FPF exhibited moderate or high toxicity to some aquatic species. The 5% hazardous concentration of FPF was 3.84 μg/L for aquatic organisms. We obtained 91 aerobic TPs for FPF, and almost half of FPF TPs exhibited toxicity to fish or Daphnia. Eleven of the TPs of FPF exhibited a high or moderate risk to aquatic ecosystems. All FPF TPs with high and moderate risks contained a 6-chloropyridine ring structure, indicating that the derivant of a pyridine ring exhibits potential risks to aquatic ecosystems. Our results provide insight into the potential risk of FPF to aquatic ecosystems and could be used to help set criteria to control pollution caused by FPF.

Tracing the attenuation of fipronil and its transformation products from a rice paddy field to receiving rivers using polar organic chemical integrative samplers

Irrational use of fipronil for rice pest control often occurred, resulting in high concentrations of fipronil and its transformation products (TPs) (collectively termed fiproles) in aquatic sediment, calling for a better understanding of the migration and transformation of fipronil in surface water as well as efficient methods for source identification. Herein, the fate and transport of fiproles from a paddy field to receiving rivers were assessed in Poyang Lake basin, Jiangxi, China using polar organic chemical integrative samplers with mixed-mode adsorbents (POCIS-MMA). Average concentrations of fiproles in water were 6.16 ± 6.32 ng/L, with median, minimum, and maximum values being 2.99 ± 0.67, 0.40 ± 0.08, and 18.6 ± 3.1 ng/L, respectively. In all samples, over half of fiproles (55.9 %-90.8 %) presented in the form of TPs and fipronil desulfinyl was the dominant TP. Two approaches were applied for source identification, including the change of molar concentration ratios of fipronil to its TPs and the relative attenuation values of fiproles normalized to a reference compound (acetamiprid) that was stable in aquatic environment. While the paddy field upstream was the main source of waterborne fiproles, additional input sources in the downstream region were identified. The present study indicated that the combination of attenuation of molar concentration ratios of micro-pollutants to their respective TPs and relative attenuation values of micro-pollutants' concentrations normalized to a reference compound measured by POCIS is an effective means to study the migration and transformation of micro-pollutants in field.

Fitness assessment of Mytilus galloprovincialis Lamarck, 1819 after exposure to herbicide metabolite propachlor ESA

The lack of data on the chronic effects of chloroacetanilide herbicide metabolites on non-target aquatic organisms creates a gap in knowledge about the comprehensive impacts of excessive and repeated pesticide use. Therefore, this study evaluates the long-term effects of propachlor ethanolic sulfonic acid (PROP-ESA) after 10 (T1) and 20 (T2) days at the environmental level of 3.5 μg.L^-1 (E1) and its 10x fold multiply 35 μg.L^-1 (E2) on a model organism Mytilus galloprovincialis. To this end, the effects of PROP-ESA usually showed a time- and dose-dependent trend, especially in its amount in soft mussel tissue. The bioconcentration factor increased from T1 to T2 in both exposure groups - from 2.12 to 5.30 in E1 and 2.32 to 5.48 in E2. Biochemical haemolymph profile and haemocyte viability were not affected by PROP-ESA exposure. In addition, the viability of digestive gland (DG) cells decreased only in E2 compared to control and E1 after T1. Moreover, malondialdehyde levels increased in E2 after T1 in gills, and DG, superoxidase dismutase activity and oxidatively modified proteins were not affected by PROP-ESA. Histopathological observation showed several damages to gills (e.g., increased vacuolation, over-production of mucus, loss of cilia) and DG (e.g., growing haemocyte trend infiltrations, alterations of tubules). This study revealed a potential risk of chloroacetanilide herbicide, propachlor, via its primary metabolite in the Bivalve bioindicator species M. galloprovincialis. Furthermore, considering the possibility of the biomagnification effect, the most prominent threat poses the ability of PROP-ESA to be accumulated in edible mussel tissues. Therefore, future research about the toxicity of pesticide metabolites alone or their mixtures is needed to gain comprehensive results about their impacts on living non-target organisms.

Computer-aided toxicity prediction and potential risk assessment of two novel neonicotinoids, paichongding and cycloxaprid, to hydrobionts

Paichongding (IPP) and cycloxaprid (CYC) have been effectively used as the alternative products of imidacloprid (IMI) against IMI-resistant insects and exhibit a great market potential. However, risk assessment of IPP and CYC for non-target organisms, especially ecological risk assessment for non-target aquatic organisms, is still lacking. Here, we predicted the toxicity and potential risks of IPP, CYC, and their transformation products (TPs) to hydrobionts. The results indicated that IPP and CYC could generate 428 and 113 TPs, respectively, via aerobic microbial transformation. Nearly half of the IPP TPs and nearly 41 % of the CYC TPs exhibited high or moderate toxicity to Daphnia or fish. Moreover, we found that IPP, CYC, and 80 TPs of them posed potential risks to aquatic ecosystems. Almost all harmful TPs contained a 6-chloropyridine ring structure, suggesting that this structure may be associated with the strong toxicity of these TPs to aquatic organisms, and these TPs (IPP-TP2 or CYC-TP2, IPP-TP197 or CYC-TP71, IPP-TP198 or CYC-TP72, and IPP-TP212 or CYC-TP80) may appear in aquatic environments as final products. The risks posed by these TPs to aquatic ecosystems require more attention. This study provides insights into the toxicity and ecological risks of IPP and CYC.

Predicting and assessing the toxicity and ecological risk of seven widely used neonicotinoid insecticides and their aerobic transformation products to aquatic organisms

Neonicotinoid insecticides (NIs) are widely used worldwide, accounting for 25 % of the global insecticide market, and are easily transported into surrounding aquatic ecological environments after application. At present, >80 % of surface water is contaminated by NIs globally. Some transformation products (TPs) of NIs can exhibit greater toxicity to aquatic organism than their parent products. However, few studies have evaluated the toxicity and ecological risk of the TPs of NIs. In this study, we aimed to assess the toxicity and ecological risk of seven widely used NIs and their aerobic TPs to aquatic organisms using a prediction method. We found that partial aerobic TPs of NIs have greater toxicity to aquatic organisms than their parent products, and some of them could severely damage aquatic ecosystems. Meanwhile, acetamiprid, thiacloprid, and several other TPs of NIs with a chlorinated ring structure showed strong bioconcentration abilities, which could potentially harm aquatic organisms through the food chain. Moreover, the widespread use of NIs has certain aquatic ecological risks, which should be controlled and limited. This study comprehensively evaluated the ecological risk of seven widely used NIs and their aerobic TPs to aquatic organisms for the first time. Our results could provide an important reference for assessment of the aquatic environmental risk posed by NIs and pollution control.

Long-Term Exposure to Neonicotinoid Insecticide Acetamiprid at Environmentally Relevant Concentrations Impairs Endocrine Functions in Zebrafish: Bioaccumulation, Feminization, and Transgenerational Effects

Neonicotinoid insecticides have attracted worldwide attention due to their ubiquitous occurrence and detrimental effects on aquatic organisms, yet their impacts on fish reproduction during long-term exposure remain unknown. Here, zebrafish (F0) were exposed to a neonicotinoid, acetamiprid, at 0.19-1637 μg/L for 154 d. Accumulation and biotransformation of acetamiprid were observed in adult fish, and the parent compound and its metabolite (acetamiprid-N-desmethyl) were transferred to their offspring. Acetamiprid caused slight survival reduction and significant feminization in F0 fish even at the lowest concentration. Hormone levels in F0 fish were remarkedly altered, that is, gonad 17β-estradiol (E2) significantly increased, while androstenedione decreased. The corresponding transcription of steroidogenic genes (ar, cyp19b, fshβ, gnrh2, gnrh3, and lhβ) were significantly upregulated in the brain and gonad of the females but downregulated in the males. The vtg1 gene expression in the liver of male fish was also upregulated. In addition to F0 fish, parental exposure to acetamiprid decreased hatchability and enhanced malformation of F1 embryos. Chronic exposure to acetamiprid at environmentally relevant concentrations altered hormone production and the related gene expression of the hypothalamic-pituitary-gonad (HPG) axis in a sex-dependent way, caused feminization and reproductive dysfunction in zebrafish, and impaired production and development of their offspring.

Bioassay-based identification and removal of target and suspect toxicants in municipal wastewater: Impacts of chemical properties and transformation

Municipal wastewater contains numerous chemicals and transformation products with highly diverse physiochemical properties and intrinsic toxicity; thus, it is imperative but challenging to identify major toxicants. Herein, toxicity identification evaluation (TIE) was applied to identify major toxicants in a typical municipal wastewater treatment plant (WWTP). Impacts of chemical properties on the removal of contaminants and toxicity at individual treatment stages were also examined. The WWTP influent caused 100% death of Daphnia magna and zebrafish embryos, and toxicity characterization suggested that organics, metals, and volatiles all contributed to the toxicity. Toxicity identification based on 189 target and approximately one-thousand suspect chemicals showed that toxicity contributions of organic contaminants, metals, and ammonia to D. magna were 77%, 4%, and 19%, respectively. Galaxolide, pyrene, phenanthrene, benzo[a]anthracene, fluoranthene, octinoxate, silver, and ammonia were identified as potential toxicants. Comparatively, the detected transformation products elicited lower toxicity than their respective parent contaminants. In contrast, the analyzed contaminants showed negligible contributions to the toxicity of zebrafish embryos. Removal efficiencies of these toxicants in WWTP were highly related to their hydrophobicity. Diverse transformation and removal efficiencies of contaminants in WWTPs may influence the chemical compositions in effluent and ultimately the risk to aquatic organisms in the receiving waterways.

Overarching issues on relevant pesticide transformation products in the aquatic environment: A review

The intensification of agricultural production during the last decades has forced the rapid increase in the use of pesticides that finally end up in the aquatic environment. Albeit well-documented, pesticides continue to raise researchers' attention, because of their potential adverse impacts on the environment and, inevitably, humans. Once entering the aquatic bodies, pesticides undergo biotic and abiotic processes, resulting in transformation products (TPs) that sometimes are even more toxic than the parent compounds. A substantial shift of the scientific interest in the TPs of pesticides has been observed since their environmental fate, occurrence and toxicity is still in its formative stage. In an ongoing effort to expand the existing knowledge on the topic, several interesting works have been performed mostly in European countries, such as France, Germany, Italy, Switzerland, Greece, and Spain that counts the highest number of relevant publications. Pesticide TPs have been also studied to a lesser extent in Asia, North and South America. To this end, the main objective of this review is to delineate the global occurrence, fate, toxicity as well as the analytical challenges related to pesticide TPs in surface, ground, and wastewaters, with the view to contribute to a better understanding of the environmental problems related with TPs formation. The concentration levels of the TPs, ranging from the low ng/L to high μg/L scale and distributed worldwide. Ultimately, an attempt to predict the acute and chronic toxicity of TPs has been carried out with the aid of an in-silico approach based on ECOSAR, revealing increased chronic toxicity for the majority of the identified TPs, despite the change they underwent, while a small portion of them presented serious acute toxicity values.

Tracing neonicotinoid insecticides and their transformation products from paddy field to receiving waters using polar organic chemical integrative samplers

Neonicotinoid insecticides are ubiquitous in surface water worldwide, yet the transportation and transformation of these compounds in aquatic environment remain unclear. In the present study, polar organic chemical integrative sampler with mixed-mode adsorbents (POCIS-MMA) was developed for simultaneously tracing environmental fate of seven neonicotinoids and 10 transformation products (TPs) from a paddy field to receiving waters in Poyang Lake basin, Jiangxi, China. All neonicotinoids (5.20 ± 0.75‒866 ± 143 ng/L) and seven TPs (116 ± 4‒334 ± 78 ng/L) were detected, demonstrating widespread occurrence of these insecticides in aquatic environment. Dinotefuran (up to 802 ± 139 ng/L) and its TP, 1-methyl-3- (tetrahydro-3-furylmethyl) guanidium dihydrogen (DN) (103 ± 4‒320 ± 76 ng/L) were the dominant neonicotinoids and TPs with mean concentrations of 200 ± 296 and 208 ± 58 ng/L, respectively. Spatial attenuation of neonicotinoids stretched downstream along the rivers, while TP concentrations firstly increased (D1‒S6) and then kept constant (S7‒S16) from upstream to downstream. Though paddy field was the main source of neonicotinoids, additional input sources downstream were identified by analyzing the composition of neonicotinoids and their TPs. Our study highlighted the applicability of POCIS-MMA passive sampling to investigate the transportation and transformation of neonicotinoids in agricultural waterways.

Smart Synthesis of Trimethyl Ethoxysilane (TMS) Functionalized Core-Shell Magnetic Nanosorbents Fe3O4@SiO2: Process Optimization and Application for Extraction of Pesticides

In the current study, a smart approach for synthesizing trimethyl ethoxysilane–decorated magnetic-core silica-nanoparticles (TMS-mcSNPs) and its effectiveness as nanosorbents have been exploited. While the magnetite core was synthesized using the modified Mössbauer method, Stöber method was employed to coat the magnetic particles. The objective of this work is to maximize the magnetic properties and to minimize both particle size (PS) and particle size distribution (PSD). Using a full factorial design (2^k-FFD), the influences of four factors on the coating process was assessed by optimizing the three responses (magnetic properties, PS, and PSD). These four factors were: (1) concentration of tetraethyl-orthosilicate (TEOS); (2) concentration of ammonia; (3) dose of magnetite (Fe₃O₄); and (4) addition mode. Magnetic properties were calculated as the attraction weight. Scanning electron microscopy (SEM) was used to determine PS, and standard deviation (±SD) was calculated to determine the PSD. Composite desirability function (D) was used to consolidate the multiple responses into a single performance characteristic. Pareto chart of standardized effects together with analysis of variance (ANOVA) at 95.0 confidence interval (CI) were used to determine statistically significant variable(s). Trimethyl ethoxysilane–functionalized mcSNPs were further applied as nanosorbents for magnetic solid phase extraction (TMS-MSPE) of organophosphorus and carbamate pesticides.