Pesticides in the Ebro River basin: Occurrence and risk assessment

Ecological risk assessment of pesticides in the Mijares River (eastern Spain) impacted by citrus production using wide-scope screening and target quantitative analysis

The widespread use of pesticides, especially in agricultural areas, makes necessary to control their presence in surrounding surface waters. The current study was designed to investigate the occurrence and ecological risks of pesticides and their transformation products in a Mediterranean river basin impacted by citrus agricultural production. Nineteen sites were monitored in three campaigns distributed over three different seasons. After a qualitative screening, 24 compounds was selected for subsequent quantitative analysis. As expected, the lower section of the river was most contaminated, with total concentration >5 µg/L in two sites near to the discharge area of wastewater treatment plants. The highest concentrations were found in September, after agricultural applications and when the river flow is reduced. Ecological risks were calculated using two mixture toxicity approaches (Toxic Unit and multi-substance Potentially Affected Fraction), which revealed high acute and chronic risks of imidacloprid to invertebrates, moderate-to-high risks of diuron, simazine and 2,4-D for primary producers, and moderate-to-high risks of thiabendazole for invertebrates and fish. This study shows that intensive agricultural production and the discharge of wastewater effluents containing pesticide residues from post-harvest citrus processing plants are threatening freshwater biodiversity. Further actions are recommended to control pesticide use and to reduce emissions.

Dissipation behaviour and risk assessment of fipronil and its metabolites in paddy ecosystem using GC-ECD and confirmation by GC-MS/MS

Fipronil -a broad spectrum phenylpyrazole insecticide has high level of toxicity towards environment. Therefore, an easy and reliable analytical method was developed for residue estimation of fipronil to ensure food and environmental safety. A modified QuEChERS technique was followed for estimation of fipronil (5% SC) in paddy ecosystem using GC-ECD and confirmation by GC-MS/MS. The initial residues (0.168-0.794 μg g^-1) of total fipronil i.e., sum of fipronil and its metabolites (viz., desulfinyl and sulfone) in leaf and soil were dissipated following first order kinetics. About 92-96% of fipronil residues were degraded after 15 days with half-life of 3.4-4.1 days and pre-harvest interval of 19.4-25.7 days in plant. Residues were below level of quantification (<0.005 μg g^-1) in plant and soil at harvest. The fipronil residues in rice grain present low dietary risk (RQ_d < 1) to human health. However, high risk (RQ_d > 1) was predicted for cattle health due to fipronil residues in paddy leaf up to 10 days. The residual level in soil was also at highrisk (RQ_s > 1) for soil ecological health.

Development of multi-residue extraction procedures using QuEChERS and liquid chromatography tandem mass spectrometry for the determination of different types of organic pollutants in mussel

This study aimed to develop multi-residue methods for the extraction of organic pollutants in mussels (Mytilus galloprovincialis), including 11 pharmaceuticals, 5 pesticides, 5 perfluoroalkyl substances (PFASs) and 2 illicit drugs. The combination of 4 different QuEChERS methods and 12 clean-ups (a total of 44 combinations) was tested. QuEChERS included acidified (AQ), non-acidified (SQ) and their miniaturized versions. The clean-ups included 6 different conventional dispersive solid phase extraction (dSPE) plus 2 enhanced matrix removal (EMR-Lipid) and 4 SPE procedures (including sorbents focused on phospholipid removal and polymer-based). After sample analysis via HPLC-MS/MS, the three methods that provided the best results were validated in terms of linearity, accuracy, precision, sensitivity and matrix effect. The methods selected were the combination of (i) SQ and EMR-Lipid, (ii) AQ and Z-sep+ bulk-based dSPE and (iii) AQ and graphitized carbon black (GCB)-based dSPE. Recoveries at two concentration levels (50 and 500 ng/g) ranged 54-124%, 59-124% and 60-127%, respectively, and limits of quantification (LOQs) were < 30 ng/g for most analytes using any of the methods. The three methods were tested in non-spiked mussel samples purchased in local markets, but organic pollutants were not detected in any sample. However, the methods probed to successfully extract a wide range of organic pollutants families in mussel samples from the market and from bioaccumulation trials.

Pollutants affect algae-bacteria interactions: A critical review

With increasing concerns on the ecological risks of pollutants, many efforts have been devoted to revealing the toxic effects of pollutants on algae or bacteria in their monocultures. However, how pollutants affect algae and bacteria in their cocultures is still elusive but crucial due to its more environmental relevance. The present review outlines the interactions between algae and bacteria, reveals the influential mechanisms of pollutants (including pesticides, metals, engineered nanomaterials, pharmaceutical and personal care products, and aromatic pollutants) to algae and bacteria in their coexisted systems, and puts forward prospects for further advancing toxic studies in algal-bacterial systems. Pollutants affect the physiological and ecological functions of bacteria and algae by interfering with their relationships. Cell-to-cell adhesion, substrate exchange and biodegradation of organic pollutants, enhancement of signal transduction, and horizontal transfer of tolerance genes are important defense strategies in algal-bacterial systems to cope with pollution stress. Developing suitable algal-bacterial models, identifying cross-kingdom signaling molecules, and deciphering the horizontal transfer of pollutant resistant genes between algae and bacteria under pollution stress are the way forward to fully exploit the risks of pollutants in natural aquatic environments.

Integrated ecosystem models (soil-water) to analyze pesticide toxicity to aquatic organisms at two different temperature conditions

In order to increase the knowledge about pesticides considering the soil-water interaction, ecosystem models (mesoscosms) were used to analyze the of leachate on the immobility and feeding rate of the cladocerans, Ceriodaphnia silvestrii and D. similis and algae Raphidocelis subcapitata, at two different temperatures. Mesocosm were filled with natural soil (latosolo) that were contaminated with insecticide/acaricide Kraft 36 EC® and fungicide Score 250 EC®, using the recommended concentration for strawberry crops (10.8 g abamectin/ha and 20 g difenoconazole/ha). Pesticides were applied once (hand sprayers) and the precipitation was simulated twice a week (Days 1, 4, 8, 11, 15 and 18). The mesocosm were kept in a room with a controlled temperature (23 and 33 °C) and photoperiod (12h light/12h dark). The Kraft 36 EC® insecticide showed toxicity for both species of cladocerans tested, with effects on immobility and feeding rate, both at 23 and 33 °C. Score 250 EC® showed to be toxic only for the experiments that analyzed the immobility of C. silvestrii at 23 °C and the feeding of D. smilis at 33 °C, demonstrating that the effects are species-specific and related to the temperature at which they are tested. While for species R. subcapitata there was an effect only for mixture treatments of the pesticides analyzed at both temperatures. Thereby, zooplanktonic organisms may be at risk when exposed to this compound even after percolating in a soil column, which could lead to effects on the entire aquatic trophic chain and that temperature can influence the organism response to the contaminant.

Clothianidin in the Tropical Sugarcane Ecosystem: Soil Persistence and Environmental Risk Assessment Under Different Organic Manuring

Clothianidin is drenched at planting to manage the termites of sugarcane. The application of organic manures at planting is also in vogue to conserve the soil moisture in the tropical ecosystem. Hence, the persistence behaviour of clothianidin was studied in the sandy clay loam soil of tropical sugarcane ecosystem under different organic manuring. The clothianidin residues persisted up to 90th DAT and reached below the limit of quantification (LOQ = 0.005 µg/g) on 105th DAT both in the manurial and non-manurial soils. The half-lives of clothianidin were in the range of 22.4-24.8 days in the manurial soils as against 21 days in the non-manurial soil, indicating the insignificant positive impact of organic manures on the soil persistence of clothianidin. The clothianidin residues in the soil were predicted to pose unacceptable to medium level of risk to earthworms during the course of its dissipation in the tropical sugarcane environment.

Assessing the risk of insecticides to Actinopterygii in the combination of ecological planting and rearing

In order to study the co-existing environment of pests and economic animals, the toxicity of 15 insecticides to Plutella xylostella, Monopterus albus, and Paramisgurnus dabryanus was tested. Combined with the recommended maximum doses in the field and bioassay, the results showed that for the three insecticides that were of relatively low toxicity to M. albus and P. dabryanus, spinetoram showed the best control effect on P. xylostella, followed by chlorfenapyr and chlorantraniliprole. However, P. xylostella showed a relatively high resistance to chlorfenapyr. Therefore, the best insecticide suitable for the fields with the cauliflower-finless eel or cauliflower-loach planting and rearing combination was spinetoram, followed by chlorantraniliprole and chlorfenapyr. Other insecticides such as emamectin benzoate, Bacillus thuringiensis (Bt), matrine, and so on were effective against the diamondback moth, but they were not suitable for use because of their high toxicity to the finless eel and loach.

Evaluation of the occurrence and fate of pesticides in a typical Mediterranean delta ecosystem (Ebro River Delta) and risk assessment for aquatic organisms

Delta ecosystems are areas of high ecologic and economic values, where wildlife commonly shares the territory with intensive agricultural activities, particularly, rice cultivation and seafood production. This work aimed at evaluating the occurrence of a wide spectrum of pesticides and transformation products in the water of irrigation and drainage channels of the Ebro River Delta (NE Spain) during the main rice-growing season, when pesticide application is at its peak. Furthermore, the impact that these contaminants may have on local ecosystems and seafood production activities was assessed. A total of 35 pesticides, mainly associated with rice cultivation, out of the 66 analyzed were detected. Bentazone, propanil, MCPA, acetamiprid, and triallate were found at the μg/L level. Cybutryne, despite being banned in the European Union, was measured for the first time in the area and at concentrations above its environmental quality standard (11-49 ng/L). Sixteen additional banned pesticides were also detected at trace levels, likely due to their desorption from soil and sediment particles. Despite its dilution when discharged into the bay, this study demonstrates that the agricultural use of pesticides may have important effects on water quality and may cause a serious hazard for aquatic non-target organisms, although other factors such as temperature and salinity may play also a relevant role. Bentazone, cybutryne, dicofol, imidacloprid, MCPA, and propanil may pose a moderate to high risk for aquatic organisms at the concentration levels measured during the rice-growing season. The co-occurrence of pesticides may result in a high risk for aquatic organisms in all sampling locations. The finding of the EU Watch List insecticides imidacloprid and acetamiprid at concentrations above their maximum acceptable method detection limit calls for control of their use and revision of their legal status.

Degradation pathway of triazole fungicides and synchronous removal of transformation products via photo-electrocatalytic oxidation tandem MoS2 adsorption

A simple and effective tandem process of photo-electrocatalytic oxidation (PECO)-MoS₂ adsorption was developed for the synchronous removal of triazole fungicides (TFs) and toxicological transformation products (TPs). In order to accurately identify trace TPs and evaluate degradation pathway during water treatment, a sensitive analytical method was developed on the basis of the stir bar sorptive extraction (SBSE) pretreatment tandem LC-MS/MS technique. Firstly, the typical TFs (PRO, TET, and DIN, C₀ = 1.0 mg/L) in actual water samples were treated under the optimal process (bias voltage 1.8 V, pH 4, irradiation intensity 50 mW/cm², 0.05 g MoS₂/100 mL, 350 rpm, adsorption of 5 min). The result indicated that the residues of PRO, TET, and DIN in secondary effluent were 0.0973, 0.0617, and 0.0012 mg/L, respectively, with the removal rates of 90.3%, 93.8%, and 99.9%, respectively, undergoing 30-min photo-electrocatalysis and 5-min adsorption. The alkaline medium was favorable for the adsorption of MoS₂ to TFs. The assessment results of potential cancer risk indicated that the residues of TFs in secondary effluent were safe for drinking water consumption. Besides, the major TPs were identified via the SBSE-HRLC-MS/MS technique, and one possible transformation pathway of TFs was proposed. TFs mainly underwent dehydrochlorination, cyclization, hydroxylation, etc. to produce a series of nitrogenous heterocyclic compounds that possess higher polarity than parents, hinting that TPs might pose potential aquatic toxicity. However, TPs can be removed synchronously by this tandem technique. The current study can provide a theoretical basis for the harmless treatment of TFs in the water environment.

Removal and environmental risk assessment of contaminants of emerging concern from irrigation waters in a semi-closed microalgae photobioreactor

The present study evaluated the efficiency of a semi-closed, tubular, horizontal photobioreactor (PBR) to treat a mixture of irrigation and rural drainage water, focusing in the removal of different contaminants of emerging concern (CECs), and evaluating the environmental impact of the resulting effluent. Target CECs included pharmaceuticals, personal care products and flame retardants. Of the 13 compounds evaluated, 11 were detected in the feed water entering the PBR, and diclofenac (DCF) (1107 ng L^-1) and N,N-diethyl-toluamide (DEET) (699 ng L^-1) were those present at the greatest concentrations. The best removal efficiencies were achieved for the pharmaceuticals diazepam (94%), lorazepam (LZP) (83%) and oxazepam (OXA) (71%), and also for ibuprofen (IBU) (70%). For the rest of the CECs evaluated, attenuation was similar to that obtained after conventional wastewater treatment, ranging from basically no elimination (carbamazepine (CBZ) and tris-(2-chloroethyl) phosphate (TCEP)) to medium efficiencies (DCF and tributyl phosphate (TBP) (50%)). Environmental risk assessment based on hazard quotients (HQs) resulted in HQ values < 0.1 (no risk associated) for most of the compounds and most of the trophic levels considered. Values between 1 and 10 (moderate risk) were obtained for tonalide (AHTN) (fish) and CBZ (invertebrates). The most sensitive trophic level was green algae, whereas fish and aquatic plants were the most resilient. Our results suggest that microalgae-based treatments could become a green, cost-effective alternative to conventional wastewater treatment regarding the efficient elimination of these contaminants.

An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 1: new molecules, metabolism, fate, and transport

With the exponential number of published data on neonicotinoids and fipronil during the last decade, an updated review of literature has been conducted in three parts. The present part focuses on gaps of knowledge that have been addressed after publication of the Worldwide Integrated Assessment (WIA) on systemic insecticides in 2015. More specifically, new data on the mode of action and metabolism of neonicotinoids and fipronil, and their toxicity to invertebrates and vertebrates, were obtained. We included the newly detected synergistic effects and/or interactions of these systemic insecticides with other insecticides, fungicides, herbicides, adjuvants, honeybee viruses, and parasites of honeybees. New studies have also investigated the contamination of all environmental compartments (air and dust, soil, water, sediments, and plants) as well as bees and apicultural products, food and beverages, and the exposure of invertebrates and vertebrates to such contaminants. Finally, we review new publications on remediation of neonicotinoids and fipronil, especially in water systems. Conclusions of the previous WIA in 2015 are reinforced; neonicotinoids and fipronil represent a major threat worldwide for biodiversity, ecosystems, and all the services the latter provide.

Pesticides contamination in the Thamirabarani, a perennial river in peninsular India: The first report on ecotoxicological and human health risk assessment

This study evaluates the distribution of pesticides and assesses the ecological and human health risks associated with pesticide residues concentration in the Thamirabarani River, the only perennial river in Tamil Nadu, India. Observed a variation in the pesticide concentration in the water (not detected (ND)-31.69 μg/L), sediments (ND-14.77 μg/kg), and fish (0.02-26.05 μg/kg). Endosulfan, aldrin, and endrin were the predominant organochlorine pesticides present in water, sediments, and fish. The average concentration of pesticides (except endosulfan) in water and sediments was found to be below the acceptable threshold as per the water and sediment quality guidelines, posing no ecological hazard to aquatic organisms. The calculated risk quotient and toxic unit (0.1 > TU/RQ ≤ 1) represent low-to-medium acute and chronic toxicity to the aquatic organisms inhabiting the river basin. The average concentration of pesticides in fish (Labeorohita) was also below the maximum residual limits set by the Codex Alimentarius Commission (CAC). However, the calculated daily intakes of endosulfan, aldrin, and endrin were above the CAC-acceptable daily intake guidelines. The human health risk assessment showed that children and adults exposed to pesticides in water and sediments through ingestion and dermal contact could have higher cancer risks (CR > 10^-4) than inhalation. This study recommends implementing effective and routine pollution management schemes to avoid pesticide threats to aquatic and human health.

Ecotoxicological evaluation of imazalil transformation products on Eisenia Andrei

Data concerning the toxicity of the transformation products of some pesticides considered emerging contaminants are still incipient. This study aimed to evaluate acute (filter paper contact and avoidance test) and chronic (assays carried out in Red yellow Ultisoil) effects of the transformation products of the fungicide imazalil (IMZ) by heterogeneous photocatalysis (TiO₂/UV) in Eisenia andrei. Some endpoints, i.e. biomass variation, disorder in reproduction and avoidance behavior, cytotoxicity (cell density and feasibility), and coelomic fluid (eleocytes and amoebocytes, immune cell) and antioxidant system (catalase (CAT) and glutathione S-transferase (GST)) changes were assessed. The studied degradation times (6, 18, 35 and 90 min) represented 70; 35; 10 and 0% of the initial IMZ concentration (5 mg L^-1). No lethality and no significant difference in biomass variations were noted in the acute contact test. Decreased GST and increased CAT activities, as well as cell typing alterations and decreased cell viability and density detected at the 90-min degradation timepoint (PDT-90) indicate direct cytotoxic IMZ transformation product effects. In the avoidance test, no significant earthworm repulsion or attraction was observed. PDT-90 transformation products were responsible for losses in biomass and a reduction in the number of earthworm cocoons and juveniles present in soil. No cytotoxic effects were observed in the long term, although increased CAT and decreased GST activities were observed. Investigations on the relative toxicity of IMZ transformation products are relevant for future discussions regarding the environmental treatment, control and destination of this compound and its derivatives.

The combined effect of clethodim (herbicide) and nitrogen variation on allelopathic interactions between Microcystis aeruginosa and Raphidiopsis raciborskii

The large-scale use of herbicides deteriorates water quality and threatens aquatic biodiversity. Unfortunately, there are few studies on the ecological effects of herbicides on toxin-producing strains of cyanobacteria under changing nutrient conditions. The objective of the present study was to investigate the effects of the herbicide clethodim and nitrogen variation on the allelopathic interactions and toxin production of Microcystis aeruginosa BCCUSP232 and Raphidiopsis raciborskii (formerly known as Cylindrospermopsis raciborskii) ITEPA1. M. aeruginosa had increased cell density when exposed to the clethodim (H +) (23.55 mg/L), whereas the highest cell density of R. raciborskii was observed in the treatment with clethodim plus limited nitrogen. Also, the cell-free exudate of R. raciborskii significantly stimulated the growth of M. aeruginosa on day 3 of the experiment. The concentration of chlorophyll-a in M. aeruginosa cultures generally increased in all the treatments, while in R. raciborskii cultures, the opposite occurred. Total microcystins (MCs) content of M. aeruginosa in the mixed cultures was 68% higher in nitrogen-enriched conditions than the control. A similar increase in MC content occurred in M. aeruginosa unialgal culture treated with R. raciborskii exudate. Total saxitoxin concentration was 81% higher in mixed cultures of R. raciborskii simultaneously exposed to high nitrogen and clethodim. Similarly, unialgal cultures of R. raciborskii exposed to either high nitrogen or clethodim had higher saxitoxins concentrations than the control. The intracellular H₂O₂ content of M. aeruginosa cultures decreased, whereas, in R. raciborskii cultures, it increased during exposure to high nitrogen and clethodim. Only R. raciborskii had a significant variation in peroxidase activity. The activities of glutathione S-transferase of both strains were higher in the presence of clethodim. These results revealed that nitrogen enrichment and the presence of clethodim might lead to the excessive proliferation of M. aeruginosa and R. raciborskii and increased production of cyanotoxins in aquatic environments.

Biological and chemical monitoring of the ecological risks of pesticides in Lake Ziway, Ethiopia

Lake Ziway, a freshwater lake located in Ethiopia, is under the pressure of pesticide and nutrient pollution due to agricultural activity and urbanization. This study has analysed concentrations of insecticides, fungicides and nutrients in water and sediment samples of Lake Ziway taken in the wet and dry season at 13 sites expected to be under different environmental stress and assessed their expected ecological impacts. Malathion, dimethoate, metalaxyl, diazinon, chlorpyrifos, fenitrothion and endosulfan were detected in more than half of the water samples, while diazinon, α-cypermethrin and endosulfan were frequently detected (>25%) in sediment samples. Higher levels of physicochemical parameters were observed at sample locations proximate to agricultural and urban activities. Risk quotients (RQ) and multi-substance Potentially Affected Fraction (msPAF_RA) were calculated to assess the ecological risk of individual and mixture of pesticides, respectively. The majority of the pesticides detected in the water of the lake showed a potential acute risk (RQ > 1), specifically the insecticides chlorpyrifos, λ-cyhalothrin and α-cypermethrin for which high potential acute risks were calculated using a 2nd tier risk assessment. Levels of pesticides in sediment showed low ecological risks. Arthropods and fishes are expected to be highly affected by mixtures of pesticides (msPAF_RA = < 1-80%) detected at locations that are proximate to smallholders' farms, and receive largescale farms' wastewater and at sites where inflow rivers join the lake. Macroinvertebrates based redundancy analysis showed the effectiveness of EPT richness to assess ecological status of the lake. Training for smallholder farmers on pesticides safety and usage, and implementation of improved effluent management mechanisms by floriculture farms are urgently needed intervention measures to reduce the pollution.

Pharmaceuticals and personal care products in a Mediterranean coastal wetland: Impact of anthropogenic and spatial factors and environmental risk assessment

The present study focused on the occurrence, distribution and risk assessment of 32 pharmaceuticals and personal care products (PPCPs) in water and sediment, as well as the surrounding soil of the irrigation channels and lake of a Mediterranean coastal wetland, the Albufera Natural Park (Valencia, Spain). Moreover, the influent and effluent of ten wastewater treatment plants (WWTPs) that treat wastewater from Valencia and the surrounding areas were also studied. BPA, caffeine, diclofenac, ethyl paraben, methyl paraben, metformin, tramadol and salicylic acid were the predominant PPCPs detected in the channels and the lake, and are in good agreement with those detected in the effluent. Furthermore, 22 PPCPs were detected in >47% of the sediment samples. Of them, BPA, ethyl paraben, furosemide, ibuprofen and salicylic acid were at higher concentrations. In contrast, only seven PPCPs were detected in >44% of the soil samples. Spatial variation showed that the concentration of many PPCPs was higher in the northern area of the park, whereas the ibuprofen concentrations were higher in the south. Differences were also observed according to the type of water used for irrigation and the land uses of the area. A risk assessment based on the hazardous quotient (HQ) indicated that caffeine is a compound of concern, and tramadol at the highest concentration showed a moderate risk for the organisms assessed. Considering the mixture of the PPCPs found at each sampling point, the green algae are at risk, particularly in those points located near the city of Valencia (the most important nearby human settlement). These results indicate the need for further studies.

Maternal exposure to imazalil disrupts intestinal barrier and bile acids enterohepatic circulation tightly related IL-22 expression in F0, F1 and F2 generations of mice

There is a growing body of evidence linking maternal exposure of environmental pollutants to intestinal and metabolic diseases that can be conserved across multiple generations. Here, female C57BL/6 mice were treated imazalil (IMZ) at dietary levels of 0, 0.025‰ and 0.25‰ during the gestation and lactation periods. The results demonstrated that IMZ treatment not only induced significant changes in the mucus secretion and ionic transport, but also disrupted the expression of antimicrobial peptides in the intestine of F0, F1 and F2 generations. In addition, IMZ exposure altered BAs metabolism and the affected the expression levels of critical genes involved in BAs synthesis, signaling, transportation and apical uptake. The immune cell-produced cytokines were displaying extraordinary changes after IMZ exposure. In particular, whether it was in F0, F1-20d, F1-7 w or F2-20d, the expression of IL-22 had the trend of markedly increasing upon IMZ exposure. Correlation analyses revealed that the expression of IL-22 was positively correlated with the change of BAs metabolites. Together, all these results indicated that IMZ exposure was perceived as a major stress by the intestinal epithelium that strongly affected the intestinal barrier function (including mucus, CFTR, AMPs, inflammation), largely in response to an alteration of BAs metabolism.

Occurrence of pesticides in waters from the largest sugar cane plantation region in the world

In this study, a multi-residue method was used to analyze 13 pesticides and 1 degradation product in surface and groundwater in the region with the largest sugar cane production in the world. The potential effects of individual pesticides and their mixtures, for aquatic life and human consumption, were evaluated. For the surface water, 2-hydroxy atrazine, diuron, carbendazim, tebuthiuron, and hexazinone were the most frequently detected (100, 94, 93, 92, and 91%, respectively). Imidacloprid (2579 ng L^-1), carbendazim (1114 ng L^-1), ametryn (1101 ng L^-1), and tebuthiuron (1080 ng L^-1) were found at the highest concentrations. For groundwater, tebuthiuron was the only quantified pesticide (107 ng L^-1). Ametryn, atrazine, diuron, hexazinone, carbofuran, imidacloprid, malathion, carbendazim, and their mixtures presented risk for the aquatic life. No risk was observed for the pesticides analyzed in this work, alone or in their mixtures for human consumption.

A SPE-HPLC-MS/MS method for the simultaneous determination of prioritised pharmaceuticals and EDCs with high environmental risk potential in freshwater

This work describes the development, optimisation and validation of an analytical method for the rapid determination of 17 priority pharmaceutical compounds and endocrine disrupting chemicals (EDCs). Rather than studying compounds from the same therapeutic class, the analyses aimed to determine target compounds with the highest risk potential (with particular regard to Scotland), providing a tool for further monitoring in different water matrices. Prioritisation was based on a systematic environmental risk assessment approach, using consumption data; wastewater treatment removal efficiency; environmental occurrence; toxicological effects; and pre-existing regulatory indicators. This process highlighted 17 compounds across various therapeutic classes, which were then quantified, at environmentally relevant concentrations, by a single analytical methodology. Analytical determination was achieved using a single-step solid phase extraction (SPE) procedure followed by high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). The fully optimised method performed well for the majority of target compounds, with recoveries >71% for 15 of 17 analytes. The limits of quantification for most target analytes (14 of 17) ranged from 0.07 ng/L to 1.88 ng/L in river waters. The utility of this method was then demonstrated using real water samples associated with a rural hospital/setting. Eight compounds were targeted and detected, with the highest levels found for the analgesic, paracetamol (at up to 105,910 ng/L in the hospital discharge). This method offers a robust tool to monitor high priority pharmaceutical and EDC levels in various aqueous sample matrices.

Structure and QSAR analysis of photoinduced transformation products of neonicotinoids from EU watchlist for ecotoxicological assessment

Current research is increasingly focusing on the ecotoxicity of anthropogenic micro-pollutants and their degradation and transformation products resulting from biological and chemical treatment processes. These products enter the aquatic environment through various routes and may endanger aquatic organisms and plants. In this study, five neonicotinoids from the EU watchlist and their degradation products induced by UVC irradiation were examined. All identified photoinduced degradation or transformation products were subsequently submitted to Quantitative Structure Activity (QSAR) analysis. Among the investigated structures, 15 substances already identified in previous studies and eleven new transformation products were analyzed. By using QSAR analysis, it became possible to predict ecotoxicity of individual substances with mere computational effort. Starting from the chemical structure, lower toxicity against green algae and invertebrates was predicted for the transformation products in general. For other aquatic target organisms, such as branchiopoda, actinopterygii and fathead minnow, the residual hazardous effect as compared to the initial compound depends on the presence of specific structural elements. For the neonicotinoids investigated, the cleavage or elimination of the nitrile or nitro group through the degradation process, was predicted to increase toxicity.

Ecological risk assessment of current-use pesticides and biocides in soils, sediments and surface water of a mixed land-use basin of the Pampas region, Argentina

The present study aimed to assess the ecological risk of 30 current-use agricultural pesticides and biocides in the soil, sediments and aquatic organisms of a mixed land-use basin located in the Depressed Pampas Region of Argentina. Risk Quotients (RQs) were used to evaluate the chronic risk in soil and aquatic organisms, while Toxic Units (TUs) were used to assess the acute risk in sediment-dwelling organisms and aquatic biota. Acetochlor, hydroxy-atrazine, glyphosate, AMPA, metolachlor, imidacloprid and tebuconazole were the only pesticide residues detected (>30%) and quantified in all the matrices evaluated. Glyphosate and AMPA showed the highest concentrations, being their mean and maximum levels 27.90-176.00 μg kg^-1 and 270-712.50 μg kg^-1 in soils, 8.28-32.0 μg kg^-1 and 6.85-17.50 μg kg^-1 in sediments, and 1.88-4.36 μg L^-1 and 0.66-1.03 μg L^-1 in surface water. The RQs in soils showed high chronic risk, mainly due to AMPA and imidacloprid. The TUs in sediments showed acute risk in dwelling organisms, mainly due to glyphosate and imidacloprid. RQs assessment showed a range of chronic risk levels according to the site/sampling event, with higher contribution of atrazine and its metabolites, and acetochlor, whereas TUs assessment showed no acute risk in aquatic biota. In contrast to Europe, in Argentina, there are no restrictions regarding the use of atrazine, acetochlor, imidacloprid and glyphosate to protect aquatic life. Thus, it is recommended that the current Argentine pesticide regulations should be modified to prevent ecological risk and protect ecosystems.

Chlorpyrifos remediation in agriculture runoff with homogeneous solar photo-Fenton reaction at near neutral pH: phytotoxicity assessment

This study represents the first application of Fe-citrate-based photo-Fenton chemistry for the degradation of chlorpyrifos (CPF) spiked into agricultural runoff, and its phytotoxicity assessment. The effects of the initial CPF concentration, time and ratio of Fe-citrate/H₂O₂ on CPF removal during the photo-Fenton reaction were investigated and modeled with analysis of variance using R software by the response-surface methodology package. According to the stationary point in original units, the optimal condition for 70.00% CPF removal was as follows: CPF = 2.5 mg L^-1 (0.0), time = 48.0 min (0.585) and Fe-citrate/H₂O₂ = 0.075 (0.539). Beside running the system at near-neutral pH, another strength of this study is related to the treatment of agricultural runoff contaminated with CPF with a raceway pond reactor, which has the advantages of simplicity of the facilities and procedures, as well as the possibility of using sunlight more efficiently in the field of applications. Finally, untreated and treated agriculture runoffs were used as irrigation to determine their phytotoxic effects on seed germination of cress (Lepidium sativum). Solar photo-Fenton treatment greatly reduced phytotoxicity of agriculture runoff and showed the highest germination percentage (70%) compared to both raw agricultural runoff (60%) and untreated CPF-spiked runoff (35%).

Distribution of organochlorine, organophosphates, carbamate, thiocarbamate, pyrethroids, and strobilurins in surface sediments of the Rio de Ondas watershed by GC-MS

The determination of some pesticides in surface sediments can provide important information about their distribution in the water column. This work aimed to determine the distribution of the classes of pesticides along the Ondas River's hydrographic basin (ORHB), in eighteen different points, during the dry and rainy periods. The pesticides were extracted from the sediment samples by solid-liquid extraction and then analyzed using a gas chromatograph coupled to mass spectrometry. After the development and validation of the method, nineteen pesticides from the group of organochlorine, organophosphates, carbamate and thiocarbamate, pyrethroids, and strobilurins were quantified in at least one point in the two collection periods, with accuracy varying between 86 and 126%. The average concentrations were 0.020 ng g^-1 (carbofuran) to 249.123 ng g^-1 (dimethoate) and 0.029 ng g^-1 (carbofuran and sulfotep) to 533.522 ng g^-1 in the dry and rainy periods, respectively. The results showed a wide distribution of pesticide residues in the ORHB, with higher levels for dimethoate, phenitrothion, and malathion, which may be related to their agricultural use in the region. In Brazil, it does not have specific legislation for maximum permitted values of pesticides in sediment, allowing for inappropriate or prohibited use and, consequently, affecting water quality.

A comprehensive review on environmental toxicity of azole compounds to fish

BACKGROUND

Azoles are considered as one of the most efficient fungicides for the treatment of humans, animals, and plant fungal pathogens. They are of significant clinical importance as antifungal drugs and are widely used in personal care products, ultraviolet stabilizers, and in aircraft for its anti-corrosive properties. The prevalence of azole compounds in the natural environment and its accumulation in fish raises questions about its impact on aquatic organisms.

OBJECTIVES

The objective of this paper is to review the scientific studies on the effects of azole compounds in fish and to discuss future opportunities for the risk evaluation.

METHODS

A systematic literature search was conducted on Web of Science, PubMed, and ScienceDirect to locate peer-reviewed scientific articles on occurrence, environmental fate, and toxicological impact of azole fungicides on fish.

RESULTS

Studies included in this review provide ample evidence that azole compounds are not only commonly detected in the natural environment but also cause several detrimental effects on fish. Future studies with environmentally relevant concentrations of azole alone or in combination with other commonly occurring contaminants in a multigenerational study could provide a better understanding.

CONCLUSION

Based on current knowledge and studies reporting adverse biological effects of azole on fish, considerable attention is required for better management and effective ecological risk assessment of these emerging contaminants.

Bifenthrin in the tropical sugarcane ecosystem: persistence and environmental risk assessment

Termites are one of the major pests of sugarcane. Bifenthrin has label claim for use against sugarcane termites and is applied at the time of planting over the cane setts in the furrows. A thorough knowledge on the dissipation kinetics of bifenthrin in the soil and cane setts provides an insight into its dynamic behavior in the soil-plant-environment continuum, and hence, was studied in detail. The recoveries of the method adopted to determine the residues of bifenthrin in the soil, sugarcane setts, stem, and leaf were in the range of 92.78-98.19% at three levels of fortification ranged between 0.01 and 0.1 μg/g of matrix. At the recommended dose (100 g a.i./ha), bifenthrin was found to persist in the soil and cane setts up to 60 and 75 days after treatment (DAT) with the half-lives of 16.4 and 25.0 days, respectively. The dissipation kinetics of bifenthrin followed the biphasic model. At double the recommended dose, the residues persisted up to 75 DAT and reached below the detectable limit (< 0.01 μg/g) on 90 DAT both in the soil and setts. The half-life of bifenthrin was 22.0 days in the sandy clay loam soil and 17.6 days in/on the sugarcane setts. In the present study, dissipation by photolysis has been ruled out, as the treated setts were not exposed to sunlight. This could be one of the reasons for longer persistence of bifenthrin in the sugarcane setts up to 75 DAT with the half-life of more than 2 weeks. The bifenthrin residues were not detected in the leaf and stem of sugarcane plant throughout the experimental period. There could be harmful effects to earthworms (risk quotient > 1.0) due to the presence of bifenthrin residues in the soil of tropical sugarcane ecosystem.

Environmental risk assessment of priority biocidal substances on Polish surface water sample

The EU directive 2013/39/EU has incorporated four biocidal compounds as priority substances: diuron, isoproturon, cybutryne, and terbutryn. The research was undertaken to determine the concentration of biocides in surface waters in three locations in southern Poland: the Wisła River in Kraków, the Wisłoka River in Mielec, and the drainage ditch draining water from arable fields located near Mielec. Environmental samples were taken in two series: winter (February) and spring (May and June). The analyses were carried out using gas chromatography with mass spectrometry. The seasonality of biocides in surface waters was observed. In winter samples, the concentrations were below MQL, while in spring, they ranged from a few to several dozen nanograms per liter. The highest concentrations of all analyzed compounds were recorded in water taken from the Wisła River. According to directive 2013/39/EU, the maximum allowable concentration was exceeded only in the case of cybutryne in water from the Wisła, both in May and in June. The assessment of the toxicity with the tested compounds was defined based on the Environmental Risk Assessment method. Low risk was estimated for diuron and isoproturon, while moderate risk for terbutryn and cybutryne.

Exposure and tiered ecological risk assessment of phthalate esters in the surface water of Poyang Lake, China

Phthalate esters (PAEs) are a class of endocrine disruptors that are produced and used extensively in China. Given its presence in various products, a great quantity of PAEs flows into different aquatic systems each year. Hence, it is important to study the pollution levels and ecological risk of PAEs. This study investigated the distribution and seasonal variation of six priority PAEs in the surface water of Poyang Lake, the largest freshwater lake in China. In the wet season, the mean concentration of the total PAEs was 0.544 ± 0.173 μg/L, while the dry season concentration (1.003 ± 0.451 μg/L) nearly doubled. The most abundant PAE congeners were di-n-butyl phthalate (DBP), followed by bis (2-ethylhexyl) phthalate (DEHP). To evaluate the ecological risks in Poyang Lake, the predicted no-effect concentrations (PNECs) of four PAEs based on non-lethal effects were derived. For diethyl phthalate (DEP), butyl benzyl phthalate (BBP), DBP, and DEHP, the PNECs were 31.6, 3.30, 2.31, and 0.0210 μg/L, respectively. The tiered ecological risk assessment showed that DEP and BBP posed no risk in Poyang Lake. Meanwhile, DBP posed a potential risk in Poyang Lake, but the risk of DEHP was unacceptable and requires more actions. Specifically, the probabilities of exceeding the threshold for the protection of 95% of the aquatic organisms (HC₅) were 3.30% and 4.43% for DEHP in the wet and dry season, respectively. This study provides an appropriate reference for the surface water management of PAE pollution in China.

Occurrence of regulated pollutants in populated Mediterranean basins: Ecotoxicological risk and effects on biological quality

Chemical stressors co-occur in mixtures into watercourses and this complicates predicting their effects on their ecological status. Our knowledge of river basin specific pollutants (RBSPs) is still limited, but it remains necessary to ensure the good chemical and ecological status. We performed an exercise on Mediterranean river sites exposed to urban and industrial pressures in order to, i) prioritize the occurring chemicals, ii) assessing the site's specific chemical risk (RQ_site), and iii) relating the chemical risk to the biological quality, using as evidences invertebrates and diatom indices. Mediterranean rivers suffer from strong pressures which lead to a poor dilution ability, which makes the inhabiting biota highly vulnerable. The most frequent pollutants in the 89 sites surveyed included pharmaceutical products such as the antibiotics azithromycin, clarithromycin, and erythromycin, and the anti-inflammatory diclofenac, and products of industrial origin such as perfluorinated PFOS, nickel, and nonylphenol. Both the diatom index IPS and the macroinvertebrate index IBMWP hold strong negative correlations to RQ_site, indicating a significant contribution of chemicals to biological impairment. Chemical contaminants (but not nutrients or dissolved organic carbon) were associated with significant changes to the taxonomic composition of invertebrate communities, but not to that of diatom communities. Our analyses indeed reveal that the impact of co-occurring chemicals translates onto negative effects in the biological quality. Our approach may be of use to evidence impacts on water resources and water quality in rivers under strong human pressure.

Occurrence and distribution of endocrine-disrupting chemicals in mariculture fish and the human health implications

The presence and distribution of endocrine-disrupting chemicals (EDCs) in the mariculture fish from Pulau Kukup, Johor of Malaysia have been studied along with the impact on human health. Six different species of mariculture fish were collected, due to their high consumption in the Asian region-especially Malaysia, to assess their levels of EDCs. The highest concentration of EDCs detected in the muscle was dexamethasone (2.37-15.84 ng/g) and (0.77-13.41 ng/g), in the liver was dexamethasone (<2.54-43.56 ng/g) and progesterone (2.23-9.78 ng/g), and in the reproductive organ are dexamethasone (<2.54-37.23 ng/g) and caffeine (0.21-18.92 ng/g). The human health risk assessment in the current study suggested that there is no potential risk to the consumer because the hazard index was below 1 (HI < 1). The present study provides information on the pollution profile of EDCs and the associated human health risk with EDCs in mariculture fish.

Herbicide residues in sediments from Lake St Lucia (iSimangaliso World Heritage Site, South Africa) and its catchment areas: Occurrence and ecological risk assessment

The impact of agricultural pesticides on sensitive aquatic ecosystems is a matter of global concern. Although South Africa is the largest user of pesticides in sub-Saharan Africa, few studies have examined the toxicological threats posed by agricultural runoff, particularly to conservation areas of international importance. This study investigated the occurrence of 11 priority listed herbicides in sediments from Lake St Lucia, located on the east coast of South Africa. While characterised by exceptionally high levels of biodiversity, Lake St Lucia is affected by agricultural runoff primarily via inflow from two major rivers; the Mkhuze and Mfolozi. Sediment samples collected from Lake St Lucia and its two major fluvial inputs reveal widespread herbicide contamination of the aquatic environment. Residues were detected in the vast majority of samples analysed, with Mkhuze (27.3 ± 17 ng g^-1) and Mfolozi (25.6 ± 20 ng g^-1) sediments characterised by similar total herbicide levels, while lower concentrations were typically detected in Lake St Lucia (12.9 ± 12 ng g^-1). Overall, the most prominent residues detected included acetochlor (3.77 ± 1.3 ng g^-1), hexazinone (2.86 ± 1.4 ng g^-1) and metolachlor (10.1 ± 8.7 ng g^-1). Ecological assessment using Risk Quotients (RQs) showed that cumulative values for triazines and anilides/aniline herbicide classes presented low to medium risk for algae and aquatic invertebrate communities. Considering the biological importance of Lake St Lucia as a nursery for aquatic organisms, it is recommended that further research on the aquatic health of the system be undertaken. Additional monitoring and investigation into mitigation strategies is suggested, particularly as agricultural activities surrounding Lake St Lucia are likely to expand in the future.

Risk Assessment of Pesticide Mixtures in Australian Rivers Discharging to the Great Barrier Reef

Rivers discharging to the Great Barrier Reef carry complex pesticide mixtures. Here we present a first comprehensive ecotoxicological risk assessment using species sensitivity distributions (SSDs), explore how risk changes with time and land use, and identify the drivers of mixture risks. The analyzed data set comprises 50 different pesticides and pesticide metabolites that were analyzed in 3741 samples from 18 river and creek catchments between 2011 and 2016. Pesticide mixtures were present in 82% of the samples, with a maximum of 23 pesticides and a median of five compounds per sample. Chemical-analytical techniques were insufficiently sensitive for at least seven pesticides (metsulfuron-methyl, terbutryn, imidacloprid, clothianidin, ametryn, prometryn, and thiamethoxam). The classical mixture concepts of concentration addition and independent action were applied to the pesticide SSDs, focusing on environmental threshold values protective for 95% of the species. Both concepts produced almost identical risk estimates. Mixture risk was therefore finally assessed using concentration addition, as the sum of the individual risk quotients. The sum of risk quotients ranges between 0.05 and 122 with a median of 0.66. An ecotoxicological risk (i.e., a sum of individual risk quotients exceeding 1) was indicated in 38.5% of the samples. Sixteen compounds accounted for 99% of the risk, with diuron, imidacloprid, atrazine, metolachlor, and hexazinone being the most important risk drivers. Analysis of land-use patterns in catchment areas showed an association between sugar cane farming and elevated risk levels, driven by the presence of diuron.

Occurrence and potential risk of organophosphorus pesticides in urbanised Linggi River, Negeri Sembilan, Malaysia

The application of organophosphorus pesticides (OPPs) increased gradually because of the rise in global food demand that triggered the agriculture sector to increase the production, leading to OPP residues in the surface water. This study elucidated the presence of OPPs and estimated its ecological risk in the riverine ecosystem of the urbanised Linggi River, Negeri Sembilan, Malaysia. The OPP concentration in surface water was determined using solid-phase extraction method and high-performance liquid chromatography coupled with diode array detection. Further, the ecological risk was estimated by using the risk quotient (RQ) method. The three OPPs, i.e. chlorpyrifos, diazinon, and quinalphos were detected with mean concentrations of 0.0275 µg/L, 0.0328 µg/L, and 0.0362 µg/L, respectively. The OPPs were at high risk (in general and worst cases) under acute exposure. The estimated risk of diazinon was observed as medium for general (RQ_m = 0.5857) and high for worst cases (RQ_ex = 4.4678). Notably, the estimated risk for chlorpyrifos was high for both general and worst cases (RQ_m = 1.9643 and RQ_ex = 11.5643) towards the aquatic ecosystem of the Linggi River. Chronic risk of quinalphos remains unknown because of the absence of toxicity endpoints. This study presented clear knowledge regarding OPP contamination and possible risk for aquatic ecosystems. Hence, OPPs should be listed as one of the main priority contaminants in pesticide mitigation management in the future.

First attempt to assess ecotoxicological risk of fifteen rare earth elements and their mixtures in sediments with diffusive gradients in thin films

Rare earth elements (REEs) are emerging contaminants due to their large scale of exploitation worldwide for using in the high-technology sector. Diffusive gradients in thin films (DGT) are a good method to measure the bioaccessibility of inorganic substances. This study is the first to evaluate the combined toxicity of REEs in sediments to aquatic biota using the DGT technique. The intertidal zone of the Pearl River Estuary (PRE) was selected as a case study, as the upper reaches of the Pearl River is a major REE reserve and production region. The DGT-labile measured concentrations of REEs (∑REEs) were found to range from 7.02-16.06 μg/L in intertidal surface sediments of the PRE. Assessment of single REE toxicity found that risk quotient (RQ) values for Y, Pr, Nd, Eu, Dy, Er, and Yb are significantly higher than 1, indicating that the adverse effects of these single REEs should be not ignored. The combined toxicity of REE mixtures based on probabilistic ecotoxicological risk assessment, shows that intertidal surface sediments of PRE had a low probability (3.72%) of toxic effects to aquatic biota.

Presence and risk assessment of herbicides in the marine environment of Camps Bay (Cape Town, South Africa)

The present study was conducted during a time of drought to assess the concentration of herbicides and their potential for accumulation in marine biota found in the near shore marine environment of an urban setting (Camps Bay, Cape Town, South Africa). The purpose was to establish whether raw sewage containing selected persistent chemicals that are released through a local marine outfall would be sufficiently diluted by the ocean to prevent impact on the near-shore marine environment of the suburb Camps Bay. Samples of seawater, sediment, seaweed, and selected marine organisms present in the near shore environment, such as limpets (Cymbula granatina), mussels (Mytilus galloprovincialis), and sea urchins (Parechinus angulosus), were analysed for five indicator herbicides, namely atrazine, alachlor, simazine, metolachlor, and butachlor, with gas chromatography coupled with a mass spectrometer. The concentration of the compounds detected ranged from below the limit of detection (<LOD) to 4.2 ng/L in seawater, <LOD to 45.3 ng/g dry weight (dw) in sediments, <LOD to 157.8 ng/g dw in marine organisms, and between 12.3 and 87.0 ng/g dw in seaweed. Results of ecological risk assessment for acute and chronic risk, calculated following the US Environmental Protection Agency method, showed a possible threat to the near shore environment from sewage released by the marine outfall, as the herbicide contamination in the biota posed a low to high ecotoxicological risk for marine organisms. The hazard quotients and carcinogenic risk caused by herbicide pollution in Camps Bay seawater were above the acceptable level indicating that these chemicals pose adverse health effects, should an average sized human (70 kg) consume any of the marine species analysed herein on a daily basis (daily consumption of 54 g), over a lifetime period (life expectancy of 70 years). The study also indicated the extensive use of these herbicides for cosmetic and ornamental purposes in gardening, or for weed control in an urban setting, thus, it is apparent that consumers and municipalities need to be educated about their inadvertent use and safe disposal of these compounds. The use of these herbicides to control weeds within the area and discharge of sewage to Camps Bay must be checked through adequate control of the trade, handling of herbicides, and enforcement of appropriate sanctions and development of suitable regulations.

Analysis of pesticide mixtures discharged to the lagoon of the Great Barrier Reef, Australia

Organisms and ecosystems are generally exposed to mixtures of chemicals rather than to individual chemicals, but there have been relatively few detailed analyses of the mixtures of pesticides that occur in surface waters. This study examined over 2600 water samples, analysed for between 21 and 47 pesticides, from 15 waterways that discharge to the lagoon of the Great Barrier Reef in Queensland, Australia between July 1, 2011 and June 30, 2015. Essentially all the samples (99.8%) contained detectable concentrations (>limit of detection) of pesticides and pesticide mixtures. Approximately, 10% of the samples contained no quantifiable (>limit of reporting) pesticides, 10% contained one quantifiable pesticide and 80% contained quantifiable mixtures of 2-20 pesticides. Approximately 82% of samples that contained quantifiable mixtures had more than two modes of action (MoAs), but only approximately 6% had five or more MoAs. The mode, average and median number of quantifiable pesticides in all the samples were 2, 5.1 and 4, respectively. The most commonly detected compounds both individually and in mixtures were the pesticides atrazine, diuron, imidacloprid, hexazinone, 2,4-D, and the degradation product desethylatrazine. The number of pesticides and modes of action of pesticides in mixtures differed spatially and were affected by land use. Waterways draining catchments where sugar cane was a major land use had mixtures with the most pesticides.

Microalgae-based bioremediation of water contaminated by pesticides in peri-urban agricultural areas

The present study evaluated the capacity of a semi-closed, tubular horizontal photobioreactor (PBR) to remove pesticides from agricultural run-off. The study was carried out in summer (July) to study its efficiency under the best conditions (highest solar irradiation). A total of 51 pesticides, including 10 transformation products, were selected and investigated based on their consumption rate and environmental relevance. Sixteen of them were detected in the agricultural run-off, and the estimated removal efficiencies ranged from negative values, obtained for 3 compounds, namely terbutryn, diuron and imidacloprid, to 100%, achieved for 10 compounds. The acidic herbicide MCPA was removed by 88% in average, and the insecticides 2,4-D and diazinon showed variable removals, between 100% and negative values. The environmental risk associated to the compounds still present in the effluent of the PBR was evaluated using hazard quotients (HQs), calculated using the average and highest measured concentrations of the compounds. HQ values > 10 (meaning high risk) were obtained for imidacloprid (21), between 1 and 10 (meaning moderate risk) for 2,4-D (2.8), diazinon (4.6) and terbutryn (1.5), and <1 (meaning low risk) for the remaining compounds diuron, linuron and MCPA. The PBR treatment yielded variable removals depending on the compound, similarly to conventional wastewater treatment plants. This study provides new data on the capacity of microalgae-based treatment systems to eliminate a wide range of priority pesticides under real/environmental conditions.

Bioaccumulation of Pyrethroid in Parasite Wenyonia acuminata (Cestoda: Caryophyllaeidae) and Host fish Synodontis clarias (Linnaeus, 1758) from Lekki Lagoon, Lagos Nigeria

This study was aimed at determining the concentration of pyrethroid in the surface water, sediment, Weyonia acuminata and Synodontis clarias fish in Lekki lagoon, Lagos, Nigeria. In-situ physicochemical analysis of the surface water was conducted using a calibrated handheld multi-parameter probe (Horiba Checker Model U-10). Intestinal samples from infected and uninfected fish were analyzed for pyrethroid concentrations, microbial colonization, proteins (PRO), superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), malonaldehyde (MDA) and glutathione peroxidase (GPx). The histopathology of infected and uninfected intestinal tissues were analyzed using Haematoxylin and Eosin (H&E) stains and examined under a binocular light microscope (Model 230485). A total of 39 out of 98 S. clarias fish were infected with cestode parasite, Wenyonia acuminate, amounting to 39% parasite prevalence. Among the tested pyrethroids, Cyfluthrin and Alpha -cypermethrin had significant sorption of 1.62 and 3.27 respectively from the aqueous phase to the bottom sediment of the lagoon. Pyrethroid concentration was in the order of sediment > parasite> water > intestine> liver. The cholesterol, triglycerides, and LDL (low density lipids) in the parasite were higher than in the host fish (p<0.05). On the other hand, the fish hepatic protein, high density lipids (HDL) and glucose were higher than the levels in the parasites (p<0.05). There was a high prevalence of gut microbes (30 - 40%), which include Salmonella sp, Escherichia coli, Pseudomonas sp and Bacillus sp among individuals infected with gut Cestodes, Wenyonia sp compared with uninfected individual which had higher gut Staphylococcus sp., Klebsiella sp., and Proteus sp. (10- 40%). among the congeners of pyrethroids analyzed, Cyfluthrin > Alpha-Cyermethrin had significant sorption on the sediment, however unlike a benthopelagic fish, no pyrethroid was accumulated in the S. clarias from the sediment. The fish however accumulated Alpha-Cypermethrin from the aqueous phase. The parasite on the other hand accumulated Bathroid significantly from the surface water and bottom sediment which may be linked to the higher stress levels observed in the parasite than the host fish. The parasite in turn inflicted histological alterations on the host intestine, marked by moderate inflammation of mucosa, alteration of the villi microstructure, moderate stunting of the villous structure and moderate fibrosis of villous structure. The study demonstrated the efficiency of histopathological and microbial analysis in biomonitoring studies enteric parasites and early detection of pyrethroid toxicity respectively compared to bioaccumulation analysis.

Pyriproxyfen induced impairment of reproductive endocrine homeostasis and gonadal histopathology in zebrafish (Danio rerio) by altered expression of hypothalamus-pituitary-gonadal (HPG) axis genes

Pyriproxyfen (PPF), a broad-spectrum insecticide known to cause reproductive and endocrine disruption in invertebrates, while the data is scarce in aquatic vertebrates. The goal of this study is to investigate the impact of PPF on reproductive endocrine system of male and female zebrafish along hypothalamus-pituitary-gonadal (HPG) axis. In brain, PPF caused significant alteration in the transcripts of erα, lhβ, and cyp19b genes in male and fshβ, lhβ, and cyp19b genes in female zebrafish. The downstream genes of steroidogenic pathway like, star, 3βhsd, 17βhsd, and cyp19a expression were significantly altered in gonad of both sexes. Subsequent changes in circulatory steroid hormone levels lead to imbalance in hormone homeostasis as revealed from estradiol/testosterone (E₂/T) ratio. Further, the vitellogenin transcript level was enhanced in hepatic tissues and their blood plasma content was increased in male (16.21%) and declined in female (21.69%). PPF also induced histopathological changes in gonads such as, reduction of mature spermatocytes in male and vitellogenic oocytes in female zebrafish. The altered E₂/T ratio and gonadal histopathology were supported by the altered transcript levels of HPG axis genes. Overall, these findings provide new insights of PPF in zebrafish reproductive system and highlights for further investigations on its potential risks in aquatic environment.

Dissipation Kinetics and Environmental Risk Assessment of Thiamethoxam in the Sandy Clay Loam Soil of Tropical Sugarcane Crop Ecosystem

Thiamethoxam 75 SG has recently got registered for use against shoot borer and termites of sugarcane. It is the only neonicotinoid having label claim against both the major pests of sugarcane. The dissipation kinetics and environmental risk assessment of thiamethoxam 75 SG were studied in a typical tropical sugarcane crop ecosystem as detailed reports are lacking. Rapid and sensitive method adopted to determine the residues of thiamethoxam in the soil employing HPLC could provide more than 95.5% recoveries. The insecticide was observed to persist in the sandy clay loam soil for 60 days and reached below the detectable level of less than 0.01 mg/kg (LOQ = 0.01 mg/kg) on 75th day when applied @ 120 g a.i./ha. The half-life was worked out to be 16.50 days. At double the recommended dose (240 g a.i./ha), the insecticide persisted up to 75 days with the half-life of 16.91 days. The risk quotient values indicated medium to low level of risk to earthworms during the course of degradation of thiamethoxam in the soil.

Monitoring and environmental risk assessment of pesticide residues and some of their degradation products in natural waters of the Spanish vineyard region included in the Denomination of Origin Jumilla

Water pollution by pesticides used in agriculture is currently a major concern both in Spain and in Europe as a whole, prompting the need to evaluate water quality and ecological risk in areas of intensive agriculture. This study involved monitoring pesticide residues and certain degradation products in surface and ground waters of the Denomination of Origin (DO) Jumilla vineyard area in Spain. Sixty-nine pesticides were selected and evaluated at twenty-one sampling points using a multi-residue analytical method, based on solid-phase extraction (SPE) and analysis by liquid chromatography coupled with mass spectrometry (LC-MS), providing reliable results. Twenty-six compounds from those selected were detected in the samples analyzed (eleven insecticides including one degradation product, nine herbicides, and six fungicides) and fifteen of them were found in concentrations over 0.1 μg L^-1 (upper threshold established by the EU for pesticides detected in waters for human consumption). Indoxacarb was present in more than 70% of the samples, being the most frequently detected compound in water samples. Some pesticides were ubiquitous in all the water samples. Ecotoxicological risk indicators, toxic units (TUs) and risk quotients (RQs), for algae, Daphnia magna and fish were calculated to estimate the environmental risk of the presence of pesticides in waters. The compounds with the highest risk were the herbicides pendimethalin, with RQ values > 1 for the three aquatic organisms, and diflufenican, posing a high risk for algae and fish, and the insecticide chlorpyrifos, with a high risk for Daphnia magna and fish. The ∑TUi determined for water at each sampling point posed only a high risk for the three aquatic organisms in a sample. These results are important for considering the selection of pesticides with less environmental risk in intensive agricultural areas.

The removal of diuron from agricultural wastewaters by Trametes versicolor immobilized on pinewood in simple channel reactors

The presence of pesticides in agricultural wastewater entails harmful risks to both the environment and public health. In this study, two channel-type bioreactors with Trametes versicolor immobilized on pinewood chips were evaluated in terms of the removal efficiency of diuron from agricultural wastewater under non-sterile conditions. First, both single and successive sorption processes of diuron on pinewood chips were evaluated. The Freundlich model showed the best correlation in the sorption isotherm study (R² = 0.993; Δq = 5.245), but according to repeated sorption experiments, the Langmuir model (R² = 0.993; Δq = 5.757) was considered more representative. Equilibrium was reached after approximately 48 h, and the Elovich kinetic model gave the best fit with the experimental data. A packed-bed channel bioreactor (PBCB) was found to be a remarkable alternative able to remove up to 94% diuron from agricultural wastewater during 35 d. However, periodic manual mixing was required to guarantee an aerobic process, and a rotating drum bioreactor (RDB) was subsequently proposed as an enhanced version. The RDB removed up to 61% diuron during 16 d using almost 7 times lower wood dose (152 g wood·L^-1) than in the PBCB (1000 g wood·L^-1).

Pesticides in aquatic environments and their removal by adsorption methods

Although pesticides are widely used in agriculture, industry and households, they pose a risk to human health and ecosystems. Based on target organisms, the main types of pesticides are herbicides, insecticides and fungicides, of which herbicides accounted for 46% of the total pesticide usage worldwide. The movement of pesticides into water bodies occurs through run-off, spray drift, leaching, and sub-surface drainage, all of which have negative impacts on aquatic environments and humans. We sought to define the critical factors affecting the fluxes of contaminants into receiving waters. We also aimed to specify the feasibility of using sorbents to remove pesticides from waterways. In Karun River in Iran (1.21 × 10⁵ ng/L), pesticide concentrations are above regulatory limits. The concentration of pesticides in fish can reach 26.1 × 10³ μg/kg, specifically methoxychlor herbicide in Perca fluviatilis in Lithuania. During the last years, research has focused on elimination of organic pollutants, such as pesticides, from aqueous solution. Pesticide adsorption onto low-cost materials can effectively remediate contaminated waters. In particular, nanoparticle adsorbents and carbon-based adsorbents exhibit high performance (nearly 100%) in removing pesticides from water bodies.

Exposure to Environmental Levels of Pesticides Stimulates and Diversifies Evolution in Escherichia coli toward Higher Antibiotic Resistance

Antibiotic resistance is one of the most challenging issues in public health. Antibiotics have been increasingly used not only for humans and animals but also for crop protection as pesticides. Thus, antibiotics often coexist with pesticides in some environments. To investigate the effects of the co-occurring, nonantibiotic pesticides on the development of antibiotic resistance, we conducted long-term exposure experiments using an Escherichia coli K-12 model strain. The results reveal that (1) the exposure to pesticides (in mg/L) alone led to the emergence of mutants with significantly higher resistance to streptomycin; (2) the exposure to pesticides (in μg/L) together with a subinhibitory level (in high μg/L) of ampicillin synergistically stimulated the selection of ampicillin resistance and the cross-resistance to other antibiotics (i.e., ciprofloxacin, chloramphenicol, and tetracycline). Distinct and diversified genetic mutations emerged in the resistant mutants selected from the coexposure to both pesticides and ampicillin. The genetic mutations likely caused a holistic transcriptional regulation (e.g., biofilm formation, oxidative stress defense) when grown under antibiotic stress and led to increased antibiotic resistance. Together, these findings provide important fundamental insights into the development of antibiotic resistance and the resistance mechanisms under environmentally relevant conditions where antibiotics and nonantibiotic micropollutants coexist.

Occurrences of 29 pesticides in the Huangpu River, China: Highest ecological risk identified in Shanghai metropolitan area

To investigate the occurrence and risk of pesticides in the Huangpu River basin, spatial and temporal concentration variations of 29 commonly used pesticides and their risk quotient (RQ) values for three different trophic organisms (fish, daphnia, green algae) from 16 sampling sites were conducted in 2018-2019. These 29 pesticides include 4 carbamates, 2 benzimidazoles, 6 neonicotinoids, 2 organophosphates, 9 triazoles, and 6 others. Of the 29 pesticides analyzed, 18 were present in every sample taken from the Huangpu River. The concentration of target pesticides in water samples ranged from < LOQ (for buprofezin in summer, autumn, and winter) to 607.30 ng L^-1 (for carbendazim in spring). From the source (i.e., Taihu Lake) to the estuary of the Huangpu River, with the exception of isocarbophos and isoprothiolane (gradual decrease), the spatial variation of target pesticide concentrations firstly exhibited an increasing trend and then a decreasing trend. Peak spatial variation was seen in metropolitan area, which is closely related to the type of land use and the discharge of tributaries. In addition, the total summed concentration of the 29 pesticides during winter (1037.60 ng L^-1) was higher than summer (788.82 ng L^-1) in rural and metropolitan areas. For the ecological risk assessments of fish, daphnia, and green algae, the triazoles, carbamates, neonicotinoids were risk-dominant pesticides, respectively. Notably, carbendazim had a 100% detection frequency and the highest concentration of the 29 pesticides analyzed, indicating its high consumption in the Huangpu River basin.

Dissipation kinetics, dietary and ecological risk assessment of chlorantraniliprole residue in/on tomato and soil using GC-MS

An alternate single quadrupole gas chromatography coupled with electron ionization mass spectrometry (GC-EI-MS) method was developed and validated for the determination chlorantraniliprole residue in tomato and soil. The target analyte was extracted from selected matrices with acetonitrile followed by dispersive solid-phase extraction clean up with primary secondary amine and graphitized carbon black sorbent to remove co-extractives prior to analysis. Limit of quantification of the method was 0.01 μg/g and the recovery of chlorantraniliprole was in the range of 92-99% with RSD of less than 3%. The dissipation kinetics of chlorantraniliprole in tomato and soil followed first-order kinetics with the half-life of 1.26 and 1.77 days, respectively. A safe waiting period of 1 day suggested for safe consumption of tomato fruits considering the FSSAI maximum residue limit of 0.6 μg/g. The residue concentrations were reduced in the range of 13 to 64% from tomato fruit using simple household approaches. The present study suggested that the use of chlorantraniliprole in tomato does not seem to pose any dietary risk to consumers. The ecological risk quotient (RQ) values indicated that the chlorantraniliprole residues in the soil may pose a medium level of risk to earthworms and arthropods during this period.

Multiple Stressors Determine Community Structure and Estimated Function of River Biofilm Bacteria

Freshwater ecosystems are exposed to multiple stressors, but their individual and combined effects remain largely unexplored. Here, we investigated the response of stream biofilm bacterial communities to warming, hydrological stress, and pesticide exposure. We used 24 artificial streams on which epilithic (growing on coarse sediments) and epipsammic (growing on fine sediments) stream biofilms were maintained. Bacterial community composition and estimated function of biofilms exposed during 30 days to individual and combined stressors were assessed using 16S rRNA gene metabarcoding. Among the individual effects by stressors, hydrological stress (i.e., a simulated low-flow situation) was the most relevant, since it significantly altered 57% of the most abundant bacterial taxa (n = 28), followed by warming (21%) and pesticide exposure (11%). Regarding the combined effects, 16% of all stressor combinations resulted in significant interactions on bacterial community composition and estimated function. Antagonistic responses prevailed (57 to 89% of all significant interactions), followed by synergisms (11 to 43%), on specific bacterial taxa, indicating that multiple-stressor scenarios could lead to unexpected shifts in the community composition and associated functions of riverine bacterial communities.IMPORTANCE Freshwater ecosystems such as rivers are of crucial importance for human well-being. However, human activities result in many stressors (e.g., toxic chemicals, increased water temperatures, and hydrological alterations) cooccurring in rivers and streams worldwide. Among the many organisms inhabiting rivers and streams, bacteria are ecologically crucial; they are placed at the base of virtually all food webs and they recycle the organic matter needed for bigger organisms. Most of these bacteria are in close contact with river substratum, where they form the biofilms. There is an urgent need to evaluate the effects of these stressors on river biofilms, so we can anticipate future environmental problems. In this study, we experimentally exposed river biofilms to a pesticide mixture, an increase in water temperature and a simulated low-flow condition, in order to evaluate the individual and joint effects of these stressors on the bacterial community composition and estimated function.

Cytogenetic and genotoxic assessment in Allium cepa exposed to imazalil fungicide

Imazalil (IMZ), a fungicide containing imidazole group, is extensively used for the prevention and treatment of fungal diseases in plants. Current study was performed to examine cyto-genotoxic potential of IMZ on Allium cepa roots by following Allium ana-telophase and single cell gel electrophoresis (comet) assays. The concentration which reduced the growth of the root tips of IMZ by 50% compared to the negative control group (EC₅₀) was found to be 1 μg/mL by Allium root growth inhibition test. 0.5, 1, and 2 μg/mL concentrations of IMZ were exposed to Allium roots for intervals of 24, 48, 72, and 96 h. 10 μg/mL of methyl methane sulfonate (MMS) and distilled water were used as control groups, both positive and negative. Statistical analysis was performed by using one-way ANOVA with Duncan's multiple comparison tests at p ≤ 0.05 and Pearson correlation test at p = 0.01. IMZ showed cytotoxic effect by statistically decreasing root growth and mitotic index (MI) and also genotoxic effect by statistically increasing chromosomal aberrations (CAs) and DNA damage compared to the negative control group. With these cyto-genotoxic effects, it should be used carefully and further cyto-genotoxic mechanisms should be investigated along with other toxicity tests.

Persistence, dietary and ecological risk assessment of indoxacarb residue in/on tomato and soil using GC-MS

An efficient single quadrupole gas chromatography with mass spectrometry method was developed and validated for the determination of indoxacarb residues in tomato and soil. Residues were extracted from the samples using acetonitrile as extracting solvent and the extracts were purified through primary secondary amine and graphitized carbon black. Recoveries were obtained in the range of 92.12-110.51% with the relative standard deviation of 1.32-4.32%. Indoxacarb dissipated with half-life of 3.12-3.21 and 1.24-1.35d for tomato and soil, respectively following doses of indoxacarb 14.5% SC at 60, 90 and 120 g.a.i./ha. Safe waiting periods were found to be 1-3d. The residues were removed from tomato fruit was in the range of 16.73 to 54.32% using simple decontamination approaches. The present study suggest that the use of indoxacarb in tomato at recommended dose, does not seem to pose any dietary risk to the consumers. The soil RQ values indicated low level of risk to earthworms and arthropods.