Occurrence and ecotoxicological risk assessment of pesticides in sediments of the Rosetta branch, Nile River, Egypt

Legacy and currently-used pesticides in sedimentary archives: Anthropogenic footprint in the pearl river estuary

Pesticides are fundamental to modern agriculture but pose significant environmental risks due to their persistence, bioaccumulation potential, and toxicity. This study systematically investigates the pollution characteristics and historical trends of 28 legacy organochlorine pesticides (OCPs) and 17 currently-used pesticides (CUPs) in a sediment core from the Pearl River Estuary (PRE), assessing their potential as Anthropocene markers. The concentrations of Σ28OCPs ranged from 0.788 to 9.12 ng/g, dominated by dichlorodiphenyltrichloroethanes (DDTs, 49 ± 21 %) and chlordane (9 ± 6 %), while the Σ17CUP concentrations were an order of magnitude higher, ranging from 4.85 to 98.4 ng/g, with pyrethroids contributing 50-99 %. This shift in pesticide composition reflects the historical transition from OCPs to CUPs in China's pesticide usage. Temporal trends (1919-2019) showed that the concentrations of DDTs, chlordane, pyrethroids, and dicofol closely mirrored their usage history in China, demonstrating that sediment cores effectively record pesticide application history. Redundancy analysis identified total organic carbon, temperature, and precipitation as key environmental factors influencing the concentrations of DDTs, chlordane, pyrethroids, and dicofol. Correlation analysis further demonstrated that the concentrations of DDTs and phenothrin were linked to population, GDP, and agricultural activities, whereas dicofol, parathion-methyl, and bromophos-ethyl were primarily driven by agricultural activities. Moreover, DDT exhibited temporally abrupt trends, broad geographic signals, and permanent environmental records, suggesting its potential as a robust Anthropocene marker. This study provides critical insights into pesticide pollution dynamics and highlights the value of legacy and emerging pollutants in tracking human impacts on Earth's environmental systems.

Biochar in the Remediation of Organic Pollutants in Water: A Review of Polycyclic Aromatic Hydrocarbon and Pesticide Removal

This review explores biochar's potential as a sustainable and cost-effective solution for remediating organic pollutants, particularly polycyclic aromatic hydrocarbons (PAHs) and pesticides, in water. Biochar, a carbon-rich material produced from biomass pyrolysis, has demonstrated adsorption efficiencies exceeding 90% under optimal conditions, depending on the feedstock type, pyrolysis temperature, and functionalization. High surface area (up to 1500 m2/g), porosity, and modifiable surface functional groups make biochar effective in adsorbing a wide range of contaminants, including toxic metals, organic pollutants, and nutrients. Recent advancements in biochar production, such as chemical activation and post-treatment modifications, have enhanced adsorption capacities, with engineered biochar achieving superior performance in treating industrial, municipal, and agricultural effluents. However, scaling up biochar applications from laboratory research to field-scale wastewater treatment poses significant challenges. These include inconsistencies in adsorption performance under variable environmental conditions, the high cost of large-scale biochar production, logistical challenges in handling and deploying biochar at scale, and the need for integration with existing treatment systems. Such challenges impact the practical implementation of biochar-based remediation technologies, requiring further investigation into cost-effective production methods, long-term performance assessments, and field-level optimization strategies. This review underscores the importance of addressing these barriers and highlights biochar's potential to offer a sustainable, environmentally friendly, and economically viable solution for large-scale wastewater treatment.

Ginkgo biloba extract alleviates deltamethrin-induced testicular injury by upregulating SKP2 and inhibiting Beclin1-independent autophagy

BACKGROUND

Male infertility is a worldwide concern that is associated with a decline in sperm quality. Environmental pollutants such as deltamethrin (DM) have harmful effects on male reproductive organs. By maintaining intracellular redox homeostasis, ginkgo biloba extract (GBE) can alleviate male reproductive dysfunction. However, research on the mechanisms by which GBE alleviates reproductive toxicity induced by DM is limited.

PURPOSE

In this study, we investigated whether GBE can alleviate DM-induced testicular and Sertoli cell reproductive toxicity by modulating SKP2 and Beclin1, thus providing a theoretical basis for the development of novel therapeutic approaches.

STUDY DESIGN

We explored the role of GBE in mitigating DM-induced testicular damage, with a specific focus on the intricate involvement of ubiquitination and autophagy.

METHODS

An experimental model was constructed using ICR male mice and the TM4 cell line. Tissue, cellular, and sperm morphological changes were observed through methods such as Hematoxylin and Eosin (H&E) staining, Periodate-Schiff (PAS) staining, ultrastructural observation, immunohistochemistry, and immunofluorescence. Enzyme and hormone levels were measured, and gene and protein levels were detected using real-time quantitative polymerase chain reaction (RT-qPCR) and Western blotting techniques.

RESULTS

In vivo experiments showed that DM exposure led to decreased sex hormone levels, increased seminiferous tubule diameter and impaired spermatogenesis. Meanwhile, DM exposure was found to decrease ubiquitination levels, leading to mitochondrial damage and further escalation of mitochondrial autophagy. Furthermore, in the DM-induced cell model, the upregulation of Beclin1 expression was associated with the inhibition of the ubiquitin‒proteasome system (UPS) and SKP2, thereby exacerbating autophagy. However, GBE has demonstrated notable efficacy in alleviating the reproductive toxicity induced by DM.

CONCLUSION

Our findings highlighted that SKP2 is a key regulator of Beclin1-independent autophagy and that GBE exerts therapeutic effects by upregulating SKP2 and inhibiting Beclin1 activation, which ameliorates autophagy and reduces DM-induced testicular damage.

Unveiling the toxicological effects and risks of prometryn on red swamp crayfish (Procambarus clarkii): Health assessments, ecological, and molecular insights

Prometryn is commonly used in agricultural and non-agricultural settings. However, possible harm to aquatic organisms remains a persistent concern. Prometryn was also the only one of the 26 triazine herbicides detected in this study. Numerous studies have assessed the harmful effects of prometryn in teleost fish and shrimp. There is a lack of information regarding the ecological and human health risks, as well as the toxic mechanisms affecting crayfish. In this study, human health risk assessment (THQ) and ecological risk assessment (RQ) were conducted on P. clarkii in the rice-crayfish co-culture (IRCC) farming model. The 96 h of exposure to 0.286 mg/L and 1.43 mg/L prometryn was conducted to investigate the potential effects and molecular mechanisms of hepatopancreatic resistance to prometryn in P. clarkii. The original sample analysis revealed that the THQ calculated from the prometryn levels in the muscle and hepatopancreas was below 0.1, suggesting no threat to human health. However, the calculated RQ values were >0.1, indicating a risk to P. clarkii. Histological analysis and biochemical index detection of the experimental samples revealed that the hepatopancreatic injury and oxidative damage in P. clarkii were caused by prometryn. Moreover, transcriptome analysis identified 2512 differentially expressed genes (DEGs) after 96 h of prometryn exposure. Prometryn exposure caused significant changes in metabolic pathways, including oxoacid metabolic processes and cytochrome P450-associated drug metabolism. Further hub gene analysis via PPI indicated that exposure to prometryn may inhibit lipid synthesis, storage, and amino acid transport and affect glucose metabolic pathways and hormone synthesis. Additionally, we hypothesized that prometryn-triggered cell death could be linked to the PI3K-Akt signaling cascade. This study's findings have significant meaning for the efficient and logical application of herbicides in IRCC, ultimately aiding in advancing a highly productive agricultural system.

Assessment of trace element occurrence in Nile Tilapia from the Rosetta branch of the River Nile, Egypt: Implications for human health risk via lifetime consumption

River pollution can harm human health through direct contact, drinking water, and the consumption of contaminated fish and irrigated agricultural products. Surface water and Nile tilapia (Oreochromis niloticus) samples were collected monthly from July 2022 to June 2023 at three sites (El-Rahawy, Sabal, and Tala) along the Rosetta Nile branch in Egypt to monitor the presence of eight trace elements. The potential human health risks from consuming contaminated fish were also assessed. Iron and manganese were consistently detected in all water samples across most seasons and locations, with concentrations generally below the WHO permissible levels. All 72 analyzed fish muscle samples were found to contain trace elements. The mean concentrations of metals in the fish muscle samples, in descending order, were: iron > zinc > copper > manganese > tin > antimony > lead > mercury. Significant spatial and seasonal variations were observed in both water and fish samples. El-Rahawy was identified as the most contaminated site, with summer exhibiting the highest contamination rate compared to other seasons. Fish samples collected from El-Rahawy demonstrated the highest bioconcentration factor (BCF) values for most elements, particularly mercury, lead, iron, manganese, and antimony. Target hazard quotient (THQ) calculations for the trace elements in Nile tilapia muscles revealed that all trace elements, except antimony, had THQ values below 1, suggesting that consuming Nile tilapia from these sites is unlikely to cause adverse health effects. However, THQ values for antimony exceeded the threshold of 1, indicating a potential health risk for consumers. Although the detected trace elements in the fish were below the permissible toxicity limits, some could pose a future threat to human health, necessitating further studies, ongoing monitoring, and preventive measures.

Spatiotemporal distribution, ecological risk assessment, and human health implications of currently used pesticide (CUP) residues in the surface water of Feni River, Bangladesh

Spatiotemporal monitoring of pesticide residues in river water is urgently needed due to its negative environmental and human health consequences. The present study is to investigate the occurrence of multiclass pesticide residue in the surface water of the Feni River, Bangladesh, using an optimized salting-out assisted liquid-liquid microextraction (SALLME) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). The optimized SALLME method was developed and validated following the SANTE/11312/2021 guidelines. A total of 42 water samples were collected and analyzed to understand the spatiotemporal distribution of azoxystrobin (AZ), buprofezin (BUP), carbofuran (CAR), pymetrozine (PYM), dimethoate (DMT), chlorantraniliprole (CLP), and difenoconazole (DFN). At four spike levels (n = 5) of 20, 40, 200, and 400 μg/L, the recovery percentages were satisfactory, ranging between 71.1 % and 107.0 % (RSD ≤13.8 %). The residues ranged from below the detection level (BDL) to 14.5 μg/L. The most frequently detected pesticide was DMT (100 %), followed by CLP (52.3809-57.1429), CAR (4.7619-14.2867), and PYM (4.7619-9.5238). However, AZ and BUP were below the detection limit in the analyzed samples of both seasons. Most pesticides and the highest concentrations were detected in March 2023, while the lowest concentrations were present in August 2023.Furthermore, ecological risk assessment based on the general-case scenario (RQm) and worst-case scenario (RQex) indicated a high (RQ > 1) risk to aquatic organisms, from the presence of PYM and CLP residue in river water. Human health risk via dietary exposure was estimated using the hazard quotient (HQ). Based on the detected residues, the HQ (<1) value indicated no significant health risk. This report provides the first record of pesticide residue occurrences scenario and their impact on the river environment of Bangladesh.

Overview of deltamethrin residues and toxic effects in the global environment

Pyrethroids are synthetic organic insecticides. Deltamethrin, as one of the pyrethroids, has high insecticidal activity against pests and parasites and is less toxic to mammals, and is widely used in cities and urban areas worldwide. After entering the natural environment, deltamethrin circulates between solid, liquid and gas phases and enters organisms through the food chain, posing significant health risks. Increasing evidence has shown that deltamethrin has varying degrees of toxicity to a variety of organisms. This review summarized worldwide studies of deltamethrin residues in different media and found that deltamethrin is widely detected in a range of environments (including soil, water, sediment, and air) and organisms. In addition, the metabolism of deltamethrin, including metabolites and enzymes, was discussed. This review shed the mechanism of toxicity of deltamethrin and its metabolites, including neurotoxicity, immunotoxicity, endocrine disruption toxicity, reproductive toxicity, hepatorenal toxicity. This review is aim to provide reference for the ecological security and human health risk assessment of deltamethrin.

Evaluation of suitability and biodegradability of the organophosphate insecticides to mitigate insecticide pollution in onion farming

Organophosphates constitute a major class of pesticides widely employed in agriculture to manage insect pests. Their toxicity is attributed to their ability to inhibit the functioning of acetylcholinesterase (AChE), an essential enzyme for normal nerve transmission. Organophosphates, especially chlorpyrifos, have been a key component of the integrated pest management (IPM) in onions, effectively controlling onion maggot Delia antiqua, a severe pest of onions. However, the growing concerns over the use of this insecticide on human health and the environment compelled the need for an alternative organophosphate and a potential microbial agent for bioremediation to mitigate organophosphate pesticide pollution. In the present study, chloropyrifos along with five other organophosphate insecticides, phosmet, primiphos-methyl, isofenphos, iodofenphos and tribuphos, were screened against the target protein AChE of D. antiqua using molecular modeling and docking techniques. The results revealed that iodofenphos showed the best interaction, while tribuphos had the lowest interaction with the AChE based on comparative binding energy values. Further, protein-protein interaction analysis conducted using the STRING database and Cytoscap software revealed that AChE is linked with a network of 10 different proteins, suggesting that the function of AChE is disrupted through interaction with insecticides, potentially leading to disruption within the network of associated proteins. Additionally, an in silico study was conducted to predict the binding efficiency of two organophosphate degrading enzymes, organophosphohydrolase (OpdA) from Agrobacterium radiobacter and Trichoderma harzianum paraoxonase 1 like (ThPON1-like) protein from Trichoderma harzianum, with the selected insecticides. The analysis revealed their potential to degrade the pesticides, offering a promising alternative before going for cumbersome onsite remediation.

Evidence of strobilurin fungicides and their metabolites in Dongjiang River ecosystem, southern China: Bioaccumulation and ecological risks

Despite the widespread application of strobilurin fungicides (SFs) in agriculture, little is known about their distribution and bioaccumulation in aquatic ecosystems. In this study, the concentrations of 12 SFs and two of their metabolites were determined in abiotic (water and sediment; n = 83) and biotic (plant, algae, zooplankton, and fish; n = 123) samples collected from a subtropical freshwater ecosystem, namely, Dongjiang River wetland, in southern China. Among the 12 SFs measured, azoxystrobin (AZ) was the major fungicide found in surface water (median: 2.20 ng/L) and sediment (0.064 ng/g dry wt.). Azoxystrobin acid (AZ-acid), a metabolite of AZ, was the major analyte in the plant samples and had a median concentration at 0.36 ng/g dry wt. In algae and zooplankton, (Z)-metominostrobin was the predominant fungicide and had median concentrations of 3.52 and 5.55 ng/g dry wt., respectively. In fish muscle, dimoxystrobin (DIMO) was the major SF and had a median concentration of 0.47 ng/g dry wt. The bioconcentration factor (BCF) values of AZ-acid, trifloxystrobin (TFS), and pyraclostrobin (PYR) in algae and zooplankton and AZ-acid, PYR, TFS, TFS-acid, picoxystrobin, and DIMO in fish muscle exceeded 1000 L/kg (algae, zooplankton, and fish concentrations were expressed on a dry weight basis), suggesting that these fungicides can accumulate in biota. A positive association between log BCFs of SFs in fish and logKow of SFs and a negative correlation between log BCFs and the log solubility index were observed. Additionally, the risk quotient (RQ) was calculated to evaluate the potential ecotoxicological risk of SFs to different aquatic organisms (algae, zooplankton, and fish). The PYR and DIMO concentrations at 19 sampling sites had RQ values >0.1, indicating moderate ecotoxicological risks to aquatic organisms. This study is the first to document the widespread occurrence of SFs and their metabolites in aquatic ecosystems and to elucidate the bioaccumulation potential of SFs in aquatic organisms.

Mixed agricultural, industrial, and domestic drainage water discharge poses a massive strain on freshwater ecosystems: a case from the Nile River in Upper Egypt

Heavy metal and pesticide pollution of freshwater ecosystems, i.e., rivers, raises significant concerns worldwide, where practical solutions to reduce the threats become urgent need. Heavy metals and pesticides are top of the list of environmental toxicants endangering nature; therefore, pesticides and heavy metals were measured at 10 stations along the Al-Zennar agricultural drain and the Nile River at Assiut city in Upper Egypt, to assess potential negative impact on the water/sediment's quality. The sediment of the streambed is a sink for pesticides and heavy metals, where both water and sediments have higher contamination factor (CF) for Cd, Pb, Cr, Cu, and Zn. In addition, the Nile water is highly contaminated by PCBs. The distance to the point source and hydrodynamics (flow rate and stream gradient) has major influences in pollutant concentrations as indicated by regression models. Dilution effect and rapid sedimentation may comment on the lower concentrations of the pollutants in the Nile comparatively to the drain and on the water comparatively to the sediments. The physiochemistry of the stations has minor effect on the metal/pesticide concentration, where the variable importance of projection (VIP) of the partial least square model indicated that total dissolved solids (TDS), total suspended solids (TSS), SO42-, and BOD/TOC/COD are the main contributors to the metal/pesticide concentration. Concentrations were not correlated between water and sediment suggesting a historical accumulation in sediments and temporal variation in the pollution load in the Al-Zennar drain. Bray-Curtis clustering confirmed that heavy metals have the same anthropogenic source in contrast to natural source of both Mn and Fe.

Remediation of pesticides contaminated water using biowastes-derived carbon rich biochar

The competition impact and feedstock type on the removal of water pesticides using biochar have not yet been sufficiently investigated. Therefore, here we investigated the potentiality of three different biochars (BCs) derived from rice husk (RHB), date pit (DPB), and sugarcane bagasse (SBB) biowastes for the simultaneous removal of ten pesticides from water in a competitive adsorption system. The BCs structural characterization and morphology were investigated by XRD, FTIR spectroscopy and SEM analysis. The potential adsorption mechanisms have been investigated using various isothermal and kinetic models. RHB showed the highest removal percentages (61% for atrazine/dimethoate and 97.6% for diuron/chlorfenvinphos) followed by DPB (56% for atrazine/dimethoate and 95.4% for diuron/chlorpyrifos) and then SBB (60.8% for atrazine/dimethoate and 90.8% for chlorpyrifos/malathion). The higher adsorption capacity of RHB and DPB than SBB can be due to their high total pore volume and specific surface area (SSA). Langmuir model described well the sorption data (R2 = 0.99). Adsorption equilibrium was achieved after 60 min for RHB, and 120 min for both DPB and SBB. The optimum adsorbent dose (g/L) was 10 for RHB and 4 for DPB and SBB. The removal efficiency of pesticides was enhanced by decreasing pH from 9 to 5 by RHB and to 3 by DPB and SBB. XRD and FTIR spectroscopy confirmed that BCs contain some active adsorption groups and metal oxides such as MgO, SiO, Al2O3, CaO, and TiO2 that can play an effective role in the pesticides sorption. BET-N2 adsorption analysis demonstrated that the BC pore size contributes significantly to pesticide adsorption. These findings indicate that RHB, DPB, and SBB have ability for adsorption of water pesticides even under acidic conditions. Therefore, the rice husk, date pit, and sugarcane bagasse biowastes could be pyrolyzed and reused as effective and low-cost sorbents for elimination of hazardous substances such as pesticides in the aqueous environments.

Occurrence, spatiotemporal distribution patterns,partitioning and risk assessments of multiple pesticide residues in typical estuarine water environments in eastern China

The low terrain and the prosperous agriculture in the east of China, have caused the accumulation of pesticide residues in the estuaries. Therefore, this study analyzed the spatiotemporal distribution and partition tendency of 106 pesticides based on their abundance, frequencies, and concentrations in the aquatic environment of 16 river estuaries in 7 major basins in the eastern China by using solid-phase extraction (SPE) with high-performance liquid chromatography tandem mass spectrometry (HPLC‒MS/MS) and gas chromatography tandem mass spectrometry (GC‒MS/MS). In addition, potential risk of multiple pesticides was also evaluated. The results showed that herbicides were the dominant pesticide type, while triazines were the predominate substance group of pesticide. In addition, triadimenol, vinclozolin, diethylatrazine, prometryn, thiamethoxam, atrazine, and metalachlor were the major pesticides in the water, while prometryn, metalachlor, and atrazine were the main pesticides in the sediment. The average total concentration of pesticide was 751.15 ng/L in the dry season, 651.17 ng/L in the wet season, and 617.37 ng/L in the normal season, respectively. The estuaries of the Huai River Basin, the Yangtze River Basin, the Hai River Basin, and the Yellow River Basin have been affected by the low pollution treatment efficiency, weak infrastructure, and agricultural/non-agricultural activities in eastern China, resulting in relatively serious pesticide pollution. The estuaries of Huaihe River, Yangtze River, Xiaoqing River, and Luanhe River had large pesticide abundance and comparatively severe pesticide pollution, while the estuaries of Tuhai River and Haihe River had heavy pesticide contamination in the sediment, which might be induced by historical sedimentary factors. The log KOC values showed that except for thioketone, other pesticides were relatively stable due to the adsorption by sediment. The ecological risk assessment results indicated that insecticides had a high risk. Teenagers were the most severely affected by the noncarcinogenic risk of pesticides, while adults were mostly affected by the carcinogenic risk of pesticides. Therefore, pesticide hazards in the water environment of estuaries in eastern China needs to be further close supervision.

Efficient Removal of Deltamethrin from Aqueous Solutions Using a Novel Lanthanum Metal-Organic Framework: Adsorption Models and Optimization via Box-Behnken Design

Eliminating pesticides is essential for lowering the dangers to our environment. To do this effectively, it is crucial to find adsorbents with remarkable adsorption capacities, easy retrieval, and separation. Metal-organic frameworks (MOFs) have been extensively recognized for their exceptional ability to absorb pollutants. Therefore, we used novel lanthanum metal-organic frameworks (La-MOFs) to eliminate deltamethrin (DEL) from aqueous solutions. We proved through experimentation that the La-MOF is an efficient adsorbent for DEL from water. A study of the material revealed that the adsorbent had a surface area of 952.96 m2 per gram and a pore volume of 1.038 cm3/g. These outcomes show how this substance can absorb particles. Utilizing kinetic models and conforming to the pseudo-second-order model, a thorough analysis of the efficiency of DEL adsorption onto La-MOF was conducted. To create a perfectly tailored approach, we utilized many parameters. The synthetic La-MOF adsorbent may undergo up to five steps of adsorption-desorption and has exceptional cyclability and reusability. To confirm purifying wastewater samples in the laboratory, the presentation of the established adsorbent was evaluated. For the management of industrial effluent and water filtration, the La-MOF adsorbent offered a simple and effective solution. Our investigation suggests that the method we describe for removing DEL from wastewater samples using the La-MOF adsorbent is unique.

A novel electrochemical hybrid platform for sensitive determination of the aminoglycoside antibiotic Kasugamycin residues in vegetables

Kasugamycin residues (KASU), a pest control antibiotic, was reported as an ecosystem threat owing to its over-application in plant protection to meet the growing global need for agronomic products. Therefore, we report herein the first electrochemical sensor for fast and sensitive analysis of KASU in vegetables based on the synergetic hybridization between conducting polyserine film (poly (SER)), and carbon nanomaterials including functionalized multiwalled carbon nanotubes (fMWCNTs) and reduced graphene oxide (rGO). The sensor was characterized morphologically using Scanning electron (SEM) and atomic force Microscopy (AFM), while cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used for electrochemical characterization. Under the optimized conditions using differential pulse voltammetry (DPV), the sensor exhibited an outstanding sensitivity and selectivity, with a good linear response of 3-106 µg/mL and an assessed limit of detection and quantification of 0.40 and 1.33 µg/mL, respectively. Furthermore, the electrochemical sensor was effectively applied to quantify KASU in cucumber, zucchini, and carrots with a recovery range 95.5-100.1%, and RSD lower than 4.1% (n = 3), showing its applicability and efficiency for selective analysis of KASU in foodstuffs.

Modeling fate and transport of pesticides from dryland agriculture using SWAT model

The aim of this study was to understand pesticide fate and transport from dryland agriculture in a major drinking water basin using SWAT and to identify critical source areas in the basin. Hydrological calibration results indicated satisfactory simulation of hydrologic processes within the catchment. Long term average observed sediment values (0.16 ton/ha) were compared with the annual average simulated SWAT outputs (0.22 ton/ha). Generally, the simulated concentrations were higher than the observed values, but the distribution pattern and trends were similar among the months. Average concentrations in water were 0.036 μg/L and 0.006 μg/L for fenpropimorph and chlorpyrifos, respectively. Transfer rates of pesticides from landscape to rivers showed that 0.36% of fenpropimorph and 0.19% of the applied amount of chlorpyrifos were exported to the river. Higher amount of fenpropimorph transport from land to the reach was attributed to its lower K_oc (soil adsorption coefficient) value compared to chlorpyrifos. Higher amounts from HRUs were observed in the application month (April) and following month (May) for fenpropimorph, while the months after September showed higher amounts for chlorpyrifos. The specific HRUs (Hydrological Response Units) located in sub-basins 3, 5, 9 and 11 presented highest dissolved pesticide amounts, while HRUs in sub-basins 4 and 11 exhibited highest concentrations for adsorbed pesticides. Best management practices (BMPs) were recommended in critical subbasins to protect the watershed. Despite the limitations, the results demonstrate the potential contributions of modeling in terms of assessing pesticide loadings, critical zones and application timing.

Water vulnerability to pesticide contamination in a Brazilian semiarid watershed

This study aimed to prepare an inventory of the main active ingredients of pesticides and estimate the risk of pollution of groundwater and surface water resources in a Brazilian semiarid basin. The inventory was prepared using data from government agency databases. The contamination risk estimate was obtained using the GOSS index, Groundwater Ubiquity Score (GUS), Groundwater Screening Index (GSI), Leachability Index (LIX), US Environmental Protection Agency (USEPA) criteria, Leaching Index (LEACH), and Relative Leaching Potential Index (RLPI). The inventory identified 57 active ingredients commercialized under a well-defined chemical class. Most of these (51.5%) belong to the very dangerous class, while 43.6% belong to the moderately toxic class. The GOSS model showed that 23.7% of the active ingredients have a low potential, 50.85% have a moderate potential, and 13.56% have a high potential for surface water contamination, with its transport being associated with the sediment. The GUS index indicates a low potential for groundwater contamination. However, the GSI points to a high potential for water contamination, the USEPA criteria for a possible contamination of groundwater, and, according to the LIX, most of the pollutants do so by leaching. The information provided contributes to the management of xenobiotic compounds in arid and semiarid basins, adding to the water security effort by providing tools for the assessment of potential pesticide pollution. Integr Environ Assess Manag 2023;19:804-816. © 2022 SETAC.

Evaluating the spatial and temporal distribution of emerging contaminants in the Pearl River Basin for regulating purposes

Little information is available on how the types, concentrations, and distribution of chemicals have evolved over the years. The objective of the present study is therefore to review the spatial and temporal distribution profile of emerging contaminants with limited toxicology data in the pearl river basin over the years to build up the emerging contaminants database in this region for risk assessment and regulatory purposes. The result revealed that seven groups of emerging contaminants were abundant in this region, and many emerging contaminants had been detected at much higher concentrations before 2011. Specifically, antibiotics, phenolic compounds, and acidic pharmaceuticals were the most abundant emerging contaminants detected in the aquatic compartment, while phenolic compounds were of the most profound concern in soil. Flame retardants and plastics were the most frequently studied chemicals in organisms. The abundance of the field concentrations and frequencies varied considerably over the years, and currently available data can hardly be used for regulation purposes. It is suggested that watershed management should establish a regular monitoring scheme and comprehensive database to monitor the distribution of emerging contaminants considering the highly condensed population in this region. The priority monitoring list should be formed in consideration of historical abundance, potential toxic effects of emerging contaminants as well as the distribution of heavily polluting industries in the region.

Detection of Emerging Pollutants Using Aptamer-Based Biosensors: Recent Advances, Challenges, and Outlook

The synergistic potentialities of innovative materials that include aptamers have opened new paradigms in biosensing platforms for high-throughput monitoring systems. The available nucleobase functional moieties in aptamers offer exclusive features for bioanalytical sensing applications. In this context, compared to various in-practice biological recognition elements, the utilization of aptamers in detection platforms results in an extensive range of advantages in terms of design flexibility, stability, and sensitivity, among other attributes. Thus, the utilization of aptamers-based biosensing platforms is extensively anticipated to meet unaddressed challenges of various in-practice and standard analytical and sensing techniques. Furthermore, the superior characteristics of aptasensors have led to their applicability in the detection of harmful pollutants present in ever-increasing concentrations in different environmental matrices and water bodies, seeking to achieve simple and real-time monitoring. Considering the above-mentioned critiques and notable functional attributes of aptamers, herein, we reviewed aptamers as a fascinating interface to design, develop, and deploy a new generation of monitoring systems to aid modern bioanalytical sensing applications. Moreover, this review aims to summarize the most recent advances in the development and application of aptasensors for the detection of various emerging pollutants (EPs), e.g., pharmaceutical, and personal care products (PPCPs), endocrine-disrupting chemicals (EDCs), pesticides and other agricultural-related compounds, and toxic heavy elements. In addition, the limitations and current challenges are also reviewed, considering the technical constraints and complexity of the environmental samples.

Pesticides in sediments of the Ebro River Delta cultivated area (NE Spain): Occurrence and risk assessment for aquatic organisms

Intense agricultural activities are performed in the Ebro River Delta (NE Spain) with extensive use of pesticides. Medium to highly polar pesticides have not been studied intensively in sediments despite its larger use in the recent years. This work aimed at assessing the occurrence of 69 pesticides, including medium to highly polar compounds, in sediments collected from drainage and irrigation channels of the Ebro River Delta during the main rice growing season. In addition, an environmental risk assessment was performed to evaluate the potential adverse effects to sediment-dwelling organisms with the risk quotient approach. A total of 24 pesticides were detected in sediments with bentazone and cypermethrin exhibiting high detection frequencies (79%) as well as high mean concentration levels (61.9 and 81.8 ng g^-1 dw, respectively). Overall, the Alfacs bay, in the South of the delta, presented higher pesticide contamination than the Fangar bay, in the North. A similar pesticide distribution profile was observed in both bays, with oxadiazoles, organochlorines, pyrethroids, benzothiazinones and organophosphates as major, predominant classes. The presence of oxadiazon, pendimethalin and thifensulfuron methyl in the sediments may pose a moderate risk to sediment-dwelling organisms while bentazone, chlorpyrifos, and cypermethrin exhibited a potential high risk. Thus, the importance of the inclusion of medium to highly polar pesticides in the analysis of sediments is emphasized since some polar pesticides such as bentazone, imidacloprid, and thifensulfuron-methyl have been detected at concentrations that may pose a risk to aquatic organisms. Moreover, the co-occurrence of pesticides may potentially pose a high risk to sediment-dwelling organisms in 13 out of the 14 investigated locations. Finally, it could be concluded that the risk derived from the presence of pesticides in sediments must be assessed since some pesticides not detected at concerning levels in water, may pose a moderate/high risk in the sediments.