Organophosphate esters (OPEs) have been in use as flame retardants for many decades, with their actual usage varying over time. Knowledge of the emission history of OPEs is valuable for improving our ...prediction of their environmental loadings and associated risks. In this study, concentrations and compositions of 10 OPEs were measured in three dated sediment cores from the Palos Verdes Shelf (PVS) off the coast of Los Angeles, which has been impacted by wastewater treatment plant (WWTP) effluents for over a century. The total OPE concentrations varied from 0.68 to 1064 ng/g along the sediment profile, with two apparent peaks. The first peak occurred in the 1970s, coinciding with peak emissions from WWTPs. The second peak appeared in the 2000s and was possibly attributed to increased consumption of OPEs as replacement flame retardants. Since downward movement of OPEs in the PVS sediment bed was retarded by their slow desorption, the reconstructed history likely provided an accurate picture of OPE emissions in Southern California and North America. These findings suggest that the near-shore marine sediments affected by WWTP effluents could serve as an environmental proxy documenting history in OPE use and emissions.
Water treatment and reuse initiatives are essential to combat declining water supplies in a changing climate, especially in arid and semi-arid regions. Pollution of water resources intensifies the ...search for strategies to provide water for potable and non-potable reuse that mitigates detrimental ecological and human health effects. Fipronil and synthetic pyrethroids are common urban-use insecticides that exert aquatic toxicity at trace levels and have been often found in urban surface streams. In this study, samples were collected from the 182 ha Prado Wetlands in Southern California for seven months to assess the occurrence of fipronil and its degradation products as well as pyrethroids (bifenthrin and cyfluthrin) in water, sediment, and plants in a 4.45 ha vegetated surface flow constructed wetland (CW). Concentration-based removal values and changes in mass flux were calculated to determine the efficacy of CW treatment. Observed water concentrations were further used to calculate toxic units for the invertebrates Hyalella azteca and Chironomus dilutus. Pesticide concentrations in water, sediment, and plant samples consistently decreased during passage through the CW at all time points. Removal values for fipronil desulfinyl, fipronil sulfide, fipronil, fipronil sulfone, bifenthrin, and cyfluthrin were 100%, 99.7–100%, 57.8–88.1%, 75.6–100%, 74.7–100%, and 36.6–82.2%, respectively, and there was a general net deposition of pesticides into CW compartments. Toxic unit values decreased in every instance for both aquatic invertebrates. Settling of contaminated particles, adsorption to sediment, plant uptake or adsorption, and subsequent degradation contributed to the effective removal of these urban-use insecticides, which highlights the potential of CWs for protecting urban water quality.
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•A full-scale constructed wetland (CW) effectively treated fiproles and pyrethroids.•Wetland sediment was an important sink for fiproles and pyrethroids.•Plant uptake played a role in wetland removal of fipronil.•Sediment sorption and subsequent degradation is the primary removal pathway.•CW treatment reduced fiprole and pyrethroid toxic units for aquatic invertebrates.
Capsule: A full-scale surface flow constructed wetland reduced concentrations of common urban-use insecticides in surface water and alleviated their associated toxicities.
The issue of microplastic pollution emerged from the marine environment, but the terrestrial environment is estimated to receive annually 4-23 times more plastic wastes. Microplastic pollution in the ...soil environment has thus begun to elicit great concern. This review summarizes the observed effects of microplastic pollution on soil ecosystems as well as sorption and transport behaviors of microplastics in such environments. Microplastic pollution has been detected in various soils including agricultural/farmland, greenhouse, home garden, coastal, industrial, and floodplain soils. Microplastics affect soil physical and chemical properties, microbial and enzyme activities, and plant growth, and also pose adverse ecotoxicological effects to soil fauna. These effects depend on the concentration, size, and shape of microplastics, as well as soil texture. Microplastics are known to sorb organic and inorganic pollutants, possibly affecting the distribution of these substances in soil. Existing evidence demonstrates the negligible effect of microplastics on bioaccumulation of contaminants in soil fauna. The horizontal and vertical transport of microplastics can be facilitated by soil fauna. Pollutants associated with microplastics may disperse further following the transport of microplastics in soil. This review also highlights perspectives for future research on microplastics in soil.
•Metabolomic profile altered in the brains of bifenthrin-exposed Chinook salmon.•Metabolites involved in apoptotic responses dysregulated in exposed salmon.•Metabolites involved in inflammatory ...responses dysregulated in exposed salmon.•Caspase 3 expression significantly increased in the brains of exposed Chinook.
An increase in urban and agricultural application of pyrethroid insecticides in the San Francisco Bay Estuary and Sacramento San Joaquin Delta has raised concern for the populations of several salmonids, including Chinook salmon (Oncorhynchus tshawytscha). Bifenthrin, a type I pyrethroid, is among the most frequently detected pyrethroids in the Bay-Delta watershed, with surface water concentrations often exceeding chronic toxicity thresholds for several invertebrate and fish species. To better understand the mechanisms of bifenthrin-induced neurotoxicity, juvenile Chinook salmon were exposed to concentrations of bifenthrin previously measured in the Delta. Non-targeted metabolomic profiles were used to identify transcriptomic changes in the brains of bifenthrin-exposed fish. Pathway analysis software predicted increased apoptotic, inflammatory, and reactive oxygen species (ROS) responses in Chinook following exposure to 0.15 and 1.50 μg/L bifenthrin for 96 h. These responses were largely driven by reduced levels of inosine, hypoxanthine, and guanosine. Subsequently, in the brain, the expression of caspase 3, a predominant effector for apoptosis, was significantly upregulated following exposure to 1.50 μg/L bifenthrin. This data suggests that metabolites involved in inflammatory and apoptotic responses, as well as those involved in maintaining proper neuronal function may be disrupted following sublethal exposure to bifenthrin and further suggests that additional population studies should focus on behavioral responses associated with impaired brain function.
Urban-use pesticides present a unique risk to non-target organisms in surface aquatic systems because impervious pavement facilitates runoff that may lead to serious contamination and ensuing aquatic ...toxicity. Fipronil is an insecticide used at high rates in urban environments, especially in regions such as California. This compound and its biologically active degradation products have been detected in urban runoff drainage and downstream surface water bodies at concentrations exceeding toxicity thresholds for sensitive aquatic invertebrates, necessitating a better understanding of the runoff sources and causes of this contamination at sites of application. In this study, we evaluated sorption of fipronil, fipronil desulfinyl, fipronil sulfide, and fipronil sulfone in urban dust, soil, and concrete, matrices commonly associated with the perimeter of a residential home. Samples were also collected from five single family homes treated with fipronil in Riverside, California, for five months to determine the occurrence of fipronil and its degradates in runoff water, urban dust, soil, and on concrete surfaces. Statistical analysis was performed to determine which urban matrices contributed more significantly to the contaminant levels in runoff water. Freundlich sorption coefficients for fipronil and its degradation products in dust were 3- to 9-fold greater than their values in soil. Fipronil and its degradates were detected in 100% of runoff samples and their presence was observed in dust, soil, and concrete wipe samples for 153 d after the treatment. Linear regression analysis showed that concrete surfaces were a primary source of all four compounds to runoff, and loose dust on concrete pavement also served as an important contributor. This study represents the first comprehensive investigation of the sources and causes for surface runoff contamination by fipronil and its degradation products. Findings highlight the importance to reduce fipronil residues on concrete surfaces through improved application methods and other mitigation practices.
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•Fiproles had higher sorption affinities for dust than for soil.•Fiproles persisted for several months in urban runoff after pesticide treatment.•For the study duration, fiproles were detected in concrete, soil, and dust.•Urban dust and concrete are important sources of fiproles in runoff.
Urban dust and concrete surfaces contribute significantly to runoff of fiproles and thus represent an important target for mitigation of their offsite transport and ensuing aquatic toxicity.
The pyrethroid insecticide, bifenthrin, is frequently measured at concentrations exceeding those that induce acute and chronic toxicity to several invertebrate and fish species residing in the ...Sacramento-San Joaquin Delta of California. Since the brain is considered to be a significant target for bifenthrin toxicity, juvenile steelhead trout (Oncorhynchus mykiss) were treated with concentrations of bifenthrin found prior to (60 ng/L) and following (120 ng/L) major stormwater runoff events with nontargeted metabolomics used to target transcriptomic alterations in steelhead brains following exposure. Predicted responses were involved in cellular apoptosis and necrosis in steelhead treated with 60 ng/L bifenthrin using the software Ingenuity Pathway Analysis. These responses were predominately driven by decreased levels of acetyl-l-carnitine (ALC), docosahexaenoic acid (DHA), and adenine. Steelhead treated with 120 ng/L bifenthrin had reductions of lysophosphatidylcholines (LPC), lysophosphatidylethanolamines (LPE), and increased levels of betaine, which were predicted to induce an inflammatory response. Several genes predicted to be involved in apoptotic (caspase3 and nrf2) and inflammatory (miox) pathways had altered expression following exposure to bifenthrin. There was a significantly increased expression of caspase3 and miox in fish treated with 120 ng/L bifenthrin with a significant reduction of nrf2 in fish treated with 60 ng/L bifenthrin. These data indicate that bifenthrin may have multiple targets within the brain that affect general neuron viability, function, and signaling potentially through alterations in signaling fatty acids.
Pyrethroid insecticides are widely used in urban environments, and their occurrence has been recently associated with aquatic toxicity in urban surface streams. Synthetic pyrethroids are strongly ...hydrophobic compounds, highlighting the importance of the freely dissolved concentration (Cfree), rather than the total chemical concentration, for better prediction of potential effects in aquatic ecosystems. The goal of this study was to develop a simple, robust and field-applicable passive sampling methodology that may be used for in situ monitoring of trace levels of pyrethroids in surface water. Among a range of polymer films, polyethylene film (PE) was found to be the most efficient at absorbing pyrethroids from water. To circumvent the long equilibrium time, 13C-permethrin and bifenthrin-d5 were preloaded on the PE sampler as performance reference compounds (PRC). Desorption of isotope-labeled PRCs was found to be isotropic to the absorption of target analytes. The optimized method was first tested in large circulating tanks simulating various environmental conditions. The derived Cfree values were consistently smaller than the total aqueous concentration in salt water or water containing humic acids. The PE samplers were further deployed at multiple field sites for 7 d in Southern California and analysis demonstrated good monitoring reproducibility and sensitivity under ambient environmental conditions. The developed passive sampler approach is ideal for application for in situ sampling under field conditions, and the use of PRCs allows sampling with short and flexible time intervals.
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•A PRC-PE passive sampler was developed to measure Cfree of pyrethroids in water.•The sampler was verified under simulating conditions and field conditions.•The detection limit of this sampler was at 1 ng/L.•The PRC-PE sampler may be used for in situ monitoring.
A simple, robust and field-applicable passive sampling methodology based on preloaded PE film was developed for in situ monitoring of pyrethroids in surface water.
Intensive agricultural activities have caused land degradation due to soil pollution, particularly by pesticides. However, the degradation, metabolism, and toxicity of chiral pesticides by soil ...microorganisms are often enantioselective. This study aimed to determine the effect of chirality on the degradation of the enantiomers of ethiprole in soil and their impact on soil microbial communities. (R)‐ethiprole underwent directional chiral conversion to the (S)‐enantiomer in a paddy soil microcosm, leading to elevated concentrations of (S)‐ethiprole. Initially, the bacterial operational taxonomic units significantly decreased after 3 days of incubation with rac‐ethiprole, (R)‐ethiprole, and (S)‐ethiprole but gradually increased in the later stage. Principal coordinate analysis revealed that the bacterial community structure was enantioselectively affected by the ethiprole enantiomers. Within 3 days, both rac‐ethiprole and (R)‐ethiprole reshaped the original stochastic microbial community into a deterministic community (variable selection). Thus, we propose that the enantioselective behavior and ecotoxicology of chiral pesticides need to be considered, especially because there are numerous chiral pesticides currently in use within agricultural management. The comprehensive understanding of the ecological risk of chiral pesticide enantiomers is vital to the process of improving sustainable production and environmental health in agricultural ecosystems.
Fipronil and pyrethroids are insecticides applied at high rates in urban environments for indoor and outdoor elimination of pests such as ants, termites, roaches, and fleas. Applied residues of ...fipronil and its degradation products (hereafter: fiproles) as well as pyrethroids are easily transported offsite in surface runoff and wastewater. In surface water, fiproles and pyrethroids elicit toxicity in non-target aquatic and benthic organisms. Failing to alleviate this pollution will result in ecological impacts and as-yet-unknown human health impacts following reuse of scarce water resources. This dissertation addresses the need to reduce urban insecticide contamination of surface water by investigating urban runoff sources of fiproles and examining the comparative efficacy of a full-scale vegetated constructed wetland and a unit process open water constructed wetland in treating water contaminated with fiproles and pyrethroids. If the sources of fiproles in urban surface runoff are identified, it will be possible to modify pesticide application practices to mitigate surface water contamination by these pollutants. Therefore, runoff, soil, urban dust, and concrete wipe samples were collected from fipronil-treated homes to identify the contributions of these compartments to urban runoff of fiproles. Concrete surfaces and urban dust were shown to be the dominant contributors of fiproles to surface runoff, indicating that limiting application on these matrices would substantially reduce contamination. In addition to mitigating urban insecticide pollution, it is also necessary to uncover strategies to treat contaminated water bodies. To this end, water, sediment, and plant samples from a vegetated constructed wetland were monitored for fiproles and pyrethroids. All contaminants were effectively treated by the wetland via partitioning into sediment and subsequent degradation as well as uptake by or adsorption to aquatic macrophytes. To compare the effect of constructed wetland design on removal of fiproles and pyrethroids, water and sediment samples were also collected from a unit process open water constructed wetland. Despite the absence of macrophytes, this system was still effective for contaminant removal. Overall, this research highlights the feasibility of combining mitigation and treatment strategies to attain the goal of reducing urban insecticide contamination in surface water.
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