Sub-sewershed Monitoring to Elucidate Down-the-Drain Pesticide Sources

Unraveling the Composition Profile and Ecological Risk of Triazine Herbicides and Their Transformation Products in Urban Sewage Discharge

Triazine herbicides (THs) are used globally to control weeds in urban environments, but their transformation products (TPs) are rarely considered due to the lack of reference standards. In this study, a total of 41 TPs were found in wastewater influents and effluents of 28 municipal wastewater treatment plants (MWWTPs) from six cities in China by integrating suspect screening (36 TPs), molecular networking (9 TPs), and diagnostic fragment searching (12 TPs). Among these, 36 TPs were detected for the first time in urban aquatic environments, and 28 TPs were first reported in aquatic environments. Polar THs and their TPs were only partially removed from the aqueous phase in the wastewater treatment process. Concentrations of THs and their TPs present in wastewater effluents ranged from 107 to 435 ng/L. Thus, THs and their TPs discharged from wastewater effluents pose a medium risk to freshwater algae in the receiving waters. Moreover, 4 THs (ametryne, atrazine, terbutryn, and prometryne) and 3 TPs (atrazine-desisopropyl, TP247, and TP258) pose significant risks in several effluents. Considering the persistent and mobile properties and ecological risk of THs and their TPs, these contaminants should be specifically considered in further environmental monitoring and included in the regulation.

Characterizing pyrethroid and fipronil concentrations in biosolids

Pesticides are prevalent in wastewater, yet few studies have measured pesticides in biosolids and aqueous media from samples collected concurrently. Seventeen California wastewater treatment plants (WWTPs) were sampled in May 2020. Biosolids samples were analyzed for 27 analytes, and paired aqueous samples (influent and effluent) were analyzed for 23 analytes. Analytes included fipronil and its transformation products (fiproles), pyrethroids, novaluron, and several other pesticides with down-the-drain transport potential. Of the 27 compounds analyzed in biosolids samples, 16 were detected in at least one sample, and 10 had a detection frequency (DF) of at least 25 %. Fipronil sulfone, fipronil sulfide, and fipronil were the most frequently detected fiproles (DF = 100 %, 94 %, and 67 %, respectively); permethrin was the most frequently detected pyrethroid (DF = 100 %), followed by bifenthrin (DF = 94 %), cyhalothrin (DF = 89 %), and etofenprox (DF = 78 %). To elucidate fipronil transformation pathways within the treatment system, data from the three sample types were compared; findings were generally consistent with transformation pathways reported previously (e.g., some fiproles were rarely detected in influent or biosolids, but frequently detected in effluent, indicating their formation during the treatment process). No correlations were found between WWTP characteristics and pesticide concentrations in biosolids. The fraction of organic carbon (fOC) of each biosolids sample was measured, and a statistically significant negative correlation was observed between fOC and some fiproles, but not fipronil; possible explanations are discussed. Additional analysis for two major agricultural pesticides (bifenthrin and permethrin) indicated that estimated mass loads of these pesticides in biosolids applied to land as a soil amendment are minimal (approximately 2 to 3 orders of magnitude lower) compared to inputs from agricultural applications. This study provides insight on the magnitude of pesticides entering the environment via land-applied biosolids; existing regulations surrounding agricultural pesticide applications are expected to also be protective of the relatively low inputs from biosolids.

Environmental dynamics of pesticides: sources, impacts on amphibians, nanoparticles, and endophytic microorganism remediation

Pesticides, which are widely used in agriculture, have elicited notable environmental concern because they persist and may be toxic. The environmental dynamics of pesticides were reviewed with a focus on their sources, impacts on amphibians, and imminent remediation options. Pesticides are directly applied in ecosystems, run off into water bodies, are deposited in the atmosphere, and often accumulate in the soil and water bodies. Pesticide exposure is particularly problematic for amphibians, which are sensitive indicators of the environment's health and suffer from physiological, behavioral, and developmental disruption that has "pushed them to the brink of extinction." Finally, this review discusses the nanoparticles that can be used to tackle pesticide pollution. However, nanoparticles with large surface areas and reactivity have the potential to degrade or adsorb pesticide residues during sustainable remediation processes. Symbiotic microbes living inside plants, known as endophytic microorganisms, can detoxify pesticides. Reducing pesticide bioavailability improves plant resilience by increasing the number of metabolizing microorganisms. Synergy between nanoparticle technology and endophytic microorganisms can mitigate pesticide contamination. Results show that Interdisciplinary research is necessary to improve the application of these strategies to minimize the ecological risk of pesticides. Eco-friendly remediation techniques that promote sustainable agricultural practices, while protecting amphibian populations and ecosystem health, have advanced our understanding of pesticide dynamics.

Simultaneous quantification of carbaryl, chlorpyrifos, and paraquat in a municipal wastewater treatment plant by SPE-RP-HPLC-PDA-FD method

Three commonly used pesticides, carbaryl, chlorpyrifos, and paraquat, were quantified by using solid-phase extraction (SPE) technique and high-performance liquid chromatography with photodiode-array and fluorescence detectors (HPLC-PDA-FD) in wastewater treatment plant. After solid-phase extraction, separation, and quantification were done using a C18 analytical column, an isocratic mobile phase consisting of acetonitrile/water (70%:30% v/v) at a flow rate of 1 mL/min, and a column oven maintained at 35 °C. Analyte concentrations were detected simultaneously at 230 nm, 254 nm, and 270 nm. PDA detection at 230 nm gave LOD and LOQ values of 0.65 mg/L and 1.98 mg/L, 0.39 mg/L, and 1.17 mg/L, for carbaryl and chlorpyrifos, respectively. Fluorescence emission peaks, λexc (270 nm) and λem (320 nm), were chosen for detection. FD gave LOD and LOQ values of 0.98 mg/L and 2.96 mg/L, 1.57 mg/L, and 4.76 mg/L, for carbaryl and chlorpyrifos, respectively. Calibration curves based on integrated peak area counts gave satisfactory linearity (R2 ≥ 0.9995). Although exhibiting low detector sensitivity for paraquat at 230 nm, this method is deemed best suited for routine analysis in Wastewater Treatment Plants (WWTPs). The developed and validated method using lower-cost dual detectors, PDA-FD, as a substitute for the higher-cost mass spectrometry is suitable for routine quantitative and qualitative analysis of carbaryl, paraquat, and chlorpyrifos in wastewater and environmental samples.

Factors contributing to pesticide contamination in riverine systems: The role of wastewater and landscape sources

Wastewater treatment plant (WWTP) discharges can be a source of organic contaminants, including pesticides, to rivers. An integrated model was developed for the Potomac River watershed (PRW) to determine the amount of accumulated wastewater percentage of streamflow (ACCWW) and calculate predicted environmental concentrations (PECs) for 14 pesticides in non-tidal National Hydrography Dataset Plus Version 2.1 stream segments. Predicted environmental concentrations were compared to measured environmental concentrations (MECs) from 32 stream sites that represented a range of ACCWW and land use to evaluate model performance and to assess possible non-WWTP loading sources. Statistical agreement between PECs and MECs was strongest for insecticides, followed by fungicides and herbicides. Principal component analysis utilizing optical fluorescence and ancillary water quality data identified wastewater and urban runoff sources. Pesticides that indicated relatively larger sources from WWTPs included dinotefuran, fipronil, carbendazim, thiabendazole, and prometon whereas imidacloprid, azoxystrobin, propiconazole, tebuconazole, and diuron were more related to urban runoff. In addition, PECs generally comprised a low proportion of MECs, which indicates possible dominant loading sources beyond WWTP discharges. Cumulative potential toxicity was higher for sites with greater ACCWW and/or located in developed areas. Imidacloprid, fipronil, and carbendazim accounted for the largest portion of predicted potential toxicity across sites. The chronic aquatic life toxicity benchmarks for freshwater invertebrates were exceeded for 82 % of the imidacloprid detections (n = 28) and 47 % of the fipronil detections (n = 19). These results highlight the ecological implications of pesticide contamination from WWTP discharges and also the potential legacy effects from accumulated soil and groundwater sources. Pesticide management strategies that mitigate both current and historical impacts may improve the health of aquatic ecosystems.

Urban sewage discharge of neonicotinoids and their transformation products threatens aquatic organisms

Neonicotinoid insecticides (NEOs) are frequently used for urban landscape management and vector control, and undergo various transformation processes when release into urban environments. The discharges of NEOs and their transformation products (TPs) from urban sewer networks may pose serious threats to freshwater ecosystem integrity. However, TPs of NEOs present in municipal wastewater treatment plants (MWWTPs) and their associated risks to aquatic organisms are largely unknown. Here, we investigate NEOs and their TPs in 28 MWWTPs of six Chinese cities. Eleven NEOs and 33 TPs were identified, and 17 TPs were firstly detected in environmental medium. Considerable concentrations of NEOs and their TPs (17.0-1543 ng/L) were measured in the effluents, and two NEOs exceeded the ecological quality reference values in 32.1 % (for clothianidin) and 78.6 % (for imidacloprid) of the effluents. Simultaneously, 12 TPs had a higher regulatory priority than the corresponding NEOs in at least one aquatic organism using a toxicological priority index. Furthermore, 79.5 % of NEOs and their TPs exhibited high persistence and mobility, and thus these compounds could readily spread over long distances in aquatic environment. This study highlights that the input of NEOs and their TPs from treated wastewater into aquatic ecosystem should be regulated to mitigate the ecological risks.

Spatial distribution and risk assessment of pyrethroid insecticides in surface waters of East China Sea estuaries

Pyrethroid insecticides are the most commonly used household insecticides and pose substantial risks to marine aquatic organisms. many studies have detected pyrethroid insecticides in the waters and estuaries of the western United States, but their distributions within western Pacific estuaries have not been reported. Accordingly, we used high-throughput organic analyses combined with high volume solid-phase extraction to comprehensively assess 13 pyrethroid insecticides in East China Sea estuaries and the Huangpu River. The results demonstrated the presence of various ∑13pyrethroid insecticides in East China Sea estuaries (mean and median values of 8.45 ± 5.57 and 7.78 ng L-1, respectively), among which cypermethrin was the primary contaminant. The concentrations of ∑12pyrethroid insecticide detected in the surface waters at the Huangpu River (mean 6.7 ng L-1, outlet 16.4 ng L-1) were higher than those in the Shanghai estuary (4.7 ng L-1), suggesting that runoff from inland areas is a notable source of insecticides. Wetlands reduced the amount of runoff containing pyrethroid insecticides that reached the ocean. Several factors influenced pesticide distributions in East China Sea estuaries, and higher proportions were derived from agricultural sources than from urban sources, with a higher proportion of agricultural sources than urban sources, influenced by anthropogenic use in the region. Permethrin and cypermethrin were the main compounds contributing to the high ecological risk in the estuaries. Consequently, to prevent risks to marine aquatic life, policymakers should aim to reduce insecticide contaminants derived from urban and agricultural sources.

Spatial and temporal variability of micropollutants within a wastewater catchment system

Treated wastewater effluent is a major contributor to concentrations of many anthropogenic chemicals in the environment. Examining patterns of these compounds measured from different catchment areas comprising the influent to a wastewater treatment plant, across many months, may reveal patterns in compound sources and seasonality helpful to management efforts. This study considers a wastewater catchment system that was sampled at six sub-catchment sites plus the treatment plant influent and effluent at seven time points spanning nine months. Wastewater samples were analyzed with LC-QTOF-MS using positive electrospray ionization and GC-QTOF-MS using negative chemical ionization and electron ionization. MS data were screened against spectral libraries to identify micropollutants. As expected, multiple classes of chemicals were represented, including pharmaceuticals, plasticizers, personal care products, and flame retardants. Patterns in the compounds seen at different sampling sites and dates reflect the varying uses and down-the-drain routes that influence micropollutant loading in sewer systems. Patterns in examined compounds revealed little spatial variation, and greater temporal variation. For example, the greatest loads of DEET were found to occur in the summer months. Additionally, groups of compounds exhibited strong correlation with each other, which could be indicative of similar down-the-drain routes (such as a group intercorrelated chemicals that are components of cleaning products) or the influence of similar physicochemical processes within the sewer system. This study contributes to the understanding of dynamics of micropollutants in sewer systems.

Sea-urchin-like covalent organic framework as solid-phase microextraction fiber coating for sensitive detection of trace pyrethroid insecticides in water

Pyrethroid insecticides residues in water pose a critical threat to the environment from widespread production and overuse. Therefore, it is of major relevance to develop a sensitive and efficient method to detect pyrethroid insecticides in water. In this paper, a covalent organic framework (COF) with NHCO as the structural unit was synthesized using a simple condensation reaction of TTL (NH2) and TDBA (COOH). Various characterization results and density functional theory (DFT) calculations demonstrated that multiple interactions synergistically promoted the adsorption of pyrethroid insecticides on COFTDBA-TTL. Based on the excellent extraction capability of COFTDBA-TTL, efficient detection of 11 pyrethroid insecticides in water was achieved using COFTDBA-TTL-coated SPME fiber and gas chromatography-tandem mass spectrometry (GC-MS). The results showed that the extraction enhancement factors (EFs) of pyrethroid insecticides were as high as 2584-7199, and the extraction efficiencies were 3.28-446 times higher than that of commercial fiber, which reflected its high adsorption property. Meanwhile, the limits of detection (LODs) of the COFTDBA-TTL coated fiber were as low as 0.170-1.68 ng/L under the optimal conditions, and the recoveries of 11 pyrethroid insecticides in the actual water samples were 88.5-108 %. In conclusion, the SPME-GC-MS method based on COFTDBA-TTL coated fiber was simple, rapid, and efficient, and should have a promising application in trace detection of pyrethroid insecticides in the environment.

Pharmaceuticals, pesticides, and ultraviolet filters in wastewater discharges to San Francisco Bay as drivers of ecotoxicity

Research in the United States evaluating ecotoxic risk to receiving waters posed by contaminants occurring in wastewater discharges typically has focused on measurements of pharmaceuticals and personal care products (PPCPs), with limited evaluations of UV filters and phenylpyrazole and neonicotinoid pesticides. In this study, concentrations of 5 representative pharmaceuticals, 11 pesticides or pesticide degradation products, and 5 ultraviolet filters were measured in 24 h composite samples of six wastewater discharges representing ∼70% of the total wastewater discharged to San Francisco Bay during the summer and fall of 2021. No significant difference was observed between concentrations measured on weekdays vs. weekends. A hydrodynamic model of San Francisco Bay was used to estimate annual average dilution factors associated with different subembayments. With and without considering dilution effects, Risk Quotients were calculated using the 90th percentile of measured concentrations in wastewater effluents and threshold concentrations associated with ecotoxicity. Risk Quotients were highest for the neonicotinoid pesticide, imidacloprid, and exceeded ecotoxicity thresholds in the lower South Bay by a factor of 2.4, even when considering dilution. Compared to commonly measured pharmaceuticals, Risk Quotients for imidacloprid were higher than those for carbamazepine, trimethoprim and diclofenac, and comparable to those for propranolol and metoprolol. Risk Quotients for the pesticide, fipronil, and the UV filter, oxybenzone, were higher than for carbamazepine. The results highlight the need to incorporate pesticides and UV filters with high Risk Quotients into studies in the United States evaluating ecotoxic risk associated with contaminants in municipal wastewater discharges.