Organochlorine pesticides in the surface waters of Northern Greece

Recent updates on remediation approaches of environmentally occurring pollutants using visible light-active nano-photocatalysts

Photocatalysis emerges as a potential remedy for the issue of an unreliable light source. Recognized as the most dependable and potent energy source sustaining life on Earth, sunlight offers a promising solution. Sunlight is abundant and free, operational costs associated with running photocatalytic system using nanoparticles are often lower compared to system relying on artificial light source. The escalating problem of water pollution, particularly in highly industrialized nations, necessitates effective wastewater treatment methods. These methods aim to combat elevated pollution levels, encompassing pharmaceuticals, dyes, flame retardants, and pesticide components. Advanced oxidation processes within photocatalytic wastewater treatment exhibit substantial promise for removing complex organic pollutants. Doped nanomaterials, with their enhanced properties, enable efficient utilization of light. Coupled nanomaterials present significant potential in addressing both water and energy challenges by proficiently eliminating persistent pollutants from environment. Photocatalysis when exposed to sunlight can absorb photons and generate e- h + pairs. This discussion briefly outlines the wastewater treatment facilitated by interconnected nanomaterials, emphasizing their role in water-energy nexus. In exploring the capabilities of components within a functional photocatalyst, a comprehensive analysis of both simple photocatalysts and integrated photocatalytic systems is undertaken. Review aims to provide detailed explanation of the impact of light source on photon generation and significance of solar light on reaction kinetics, considering various parameters such as catalyst dosage, pH, temperature, and types of oxidants. By shedding light on these aspects, this review seeks to enhance our understanding of intricate processes involved in photocatalysis and its potential applications in addressing contemporary environmental challenges.

Organophosphate pesticides an emerging environmental contaminant: Pollution, toxicity, bioremediation progress, and remaining challenges

Organophosphates (OPs) are an integral part of modern agriculture; however, due to overexploitation, OPs pesticides residues are leaching and accumulating in the soil, and groundwater contaminated terrestrial and aquatic food webs. Acute exposure to OPs could produce toxicity in insects, plants, animals, and humans. OPs are known for covalent inhibition of acetylcholinesterase enzyme in pests and terrestrial/aquatic organisms, leading to nervous, respiratory, reproductive, and hepatic abnormalities. OPs pesticides also disrupt the growth-promoting machinery in plants by inhibiting key enzymes, permeability, and trans-cuticular diffusion, which is crucial for plant growth. Excessive use of OPs, directly/indirectly affecting human/environmental health, raise a thoughtful global concern. Developing a safe, reliable, economical, and eco-friendly methods for removing OPs pesticides from the environment is thus necessary. Bioremediation techniques coupled with microbes or microbial-biocatalysts are emerging as promising antidotes for OPs pesticides. Here, we comprehensively review the current scenario of OPs pollution, their toxicity (at a molecular level), and the recent advancements in biotechnology (modified biocatalytic systems) for detection, decontamination, and bioremediation of OP-pesticides in polluted environments. Furthermore, the review focuses on onsite applications of OPs degrading enzymes (immobilizations/biosensors/others), and it also highlights remaining challenges with future approaches.

Analysis of Pollution Characteristics and Sources in Surface Water in Typical Crop-Producing Areas of Qinghai Province

Currently used pesticides and organochlorine pesticides (OCPs), nitrogen and phosphorus were analyzed in surface water from 26 sampling sites of agricultural areas in Qinghai Province to elucidate their pollution characteristics and sources. The results showed that most of these currently used pesticides, with the exception of chlorpyrifos, were generally not detected. However, two OCPs were commonly detected in surface water from four typical crop-producing areas. The residual concentrations of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) measured 0~1.68 ng/L and 0.41~2.41 ng/L, respectively, in the water from the four crop-producing areas. The residues of these two OCPs pesticides were much lower than the standard limit of surface water environmental quality. The main forms of HCHs and DDTs were β-HCH and pp'-DDE, respectively, indicating that the residues of HCHs and DDTs in the surface water of the four crop-producing areas in Qinghai were mainly derived from historical drugs that had degraded for a long time. The average concentrations of TN, NO₃^--N and NH₄⁺-N in the surface water of 26 sampling sites of four typical crop areas in Qinghai Province were 2.95, 1.71 and 0.17 mg/L, respectively. According to the national surface water environmental quality standards, TN concentrations in 57.7% of these sampling sites exceeded the Class V water standards. The average concentration of NO₃^--N was more than 70 times that of NH₄⁺-N. Nonetheless, there were no significant differences in the concentrations of TN, NO₃^--N and NH₄⁺-N in the four crop-producing areas. The concentrations of NO₃^--N and NO₃^--N in the surface water were positively correlated with the TN concentration (p < 0.05), indicating that the sources of nitrogen in the surface water were relatively consistent. The average value of TP concentrations in the surface water from these sampling sites was 0.034 mg/L, with no significant differences among different producing areas. The N/P values in surface water from the four crop-producing areas of Qinghai Province had a range of 9.2~302. Phosphorus was the limiting factor for the proliferation of plankton in water. Reducing the input of phosphorus in these areas may be the key to preventing the deterioration of water quality. Significant negative and positive correlations exist between HCHs and nitrate nitrogen, and total phosphorus, respectively, which may be attributed to the proliferation of degrading microorganisms caused by the eutrophication of water. The research results will help to identify the characteristics and sources of surface water pollution in the crop-producing areas of Qinghai Province, and provide data support for Qinghai Province to build an export area for green organic agricultural and livestock products.

Utilization of montmorillonite nanocomposite incorporated with natural biopolymers and benzyl functionalized dicationic imidazolium based ionic liquid coated fiber for solid-phase microextraction of organochlorine pesticides prior to GC/MS and GC/ECD

A novel montmorillonite clay (MMT) bionanocomposite modified with chitosan (CH), carboxymethyl cellulose (CMC), and benzylimidazolium based dicationic ionic liquid with tetraethylene glycol linker (DIL) was fabricated on stainless steel wire by in situ process. The MMT-CH-CMC-DIL coated solid-phase microextraction (SPME) fiber was examined for the determination of organochlorine pesticides (OCPs) in real samples by HS-SPME-GC method using mass spectrometry (MS) and electron capture detector (ECD). Under optimized conditions, the proposed method exhibited low limits of detection (0.5 ng L^-1 with MS and 0.1 ng L^-1 with ECD detection), good linearities (R² = 0.9972-0.9993 with MS and 0.9987-0.9998 with ECD detection), favorable single-fiber repeatability, and fiber-to-fiber reproducibility (less than 8.2% and 9.9% for both types of detection) and high reusability around 125 cycles. Recovery studies were carried out for OCPs in tap water, green tea, and milk samples to verify the applicability of the developed SPME-GC method.

Recent developments in photocatalytic degradation of insecticides and pesticides

Widespread use of pesticides in agricultural and domestic sectors and their long half-life have led to their accumulation in the environment beyond permissible limits. Advanced chemical oxidation methods including photocatalytic degradation are being widely investigated for their mineralization. Photocatalytic degradation is the most promising method for degrading pesticides as well as other organic pollutants. Titanium dioxide with or without modification has been widely used as the photocatalyst. Some research groups have also tried other photocatalysts. This review presents a critical summary of the research results reported during the past two decades as well as the scope for future research in this area.

A comprehensive review of strobilurin fungicide toxicity in aquatic species: Emphasis on mode of action from the zebrafish model

Strobilurins are popular fungicides used in agriculture on a global scale. Due to their widespread use as agrochemicals, they can enter aquatic environments at concentrations that can elicit adverse effects in organisms. This review synthesizes the current state of knowledge regarding the toxic effects of strobilurin fungicides on aquatic species, including algal species, Daphnia magna, and fish species, to determine risk to aquatic organisms and ecosystems. Data show that the toxicities of strobilurins vary widely across aquatic species. Strobilurins bind cytochrome bc1 in mitochondrial complex III in fungi, and as such, research in aquatic species has focused on mitochondria-related endpoints following exposures to strobilurins. In fish, studies into the activities of mitochondrial complexes and the expression of genes involved in the electron transfer chain have been conducted, converging on the theme that mitochondrial complexes and their enzymes are impaired by strobilurins. In general, the order of toxicity of strobilurins for fish species are pyraoxystrobin > pyraclostrobin ≈ trifloxystrobin > picoxystrobin > kresoxim-methyl > fluoxastrobin > azoxystrobin. In addition to mitochondrial toxicity, studies also report genotoxicity, immunotoxicity, cardiotoxicity, neurotoxicity, and endocrine disruption, and each of these events can potentially impact whole organism-level processes such as development, reproduction, and behavior. Screening data from the US Environmental Protection Agency ToxCast database supports the hypothesis that these fungicides may act as endocrine disruptors, and high throughput data suggest estrogen receptor alpha and thyroid hormone receptor beta can be activated by some strobilurins. It is recommended that studies investigate the potential for endocrine disruption by strobilurins more thoroughly in aquatic species. Based on molecular, physiological, and developmental outcomes, a proposed adverse outcome pathway is presented with complex III inhibition in the electron transfer chain as a molecular initiating event. This review comprehensively addresses sub-lethal toxicity mechanisms of strobilurin fungicides, important as the detection of strobilurins in aquatic environments suggests exposure risks in wildlife.

Preliminary Studies of Organochlorine Pesticides (OCPs) in Sediment, Water and Fish Samples from Ethiope River, Abraka Axis, Southern Nigeria

Selected persistent organochlorine pollutants, including DDT and its metabolites, hexachlorobenzene, dieldrin, Aldrin, heptachlor, HCH as well as some of their isomers were determined in water, sediment and fish samples from the Ethiope River in Southern Nigeria. Twenty organochlorine pesticides were detected in both seasons from October 2012 – September 2013. Results revealed ∑HCH to be 0.620µg/L (water), 33 ng/g (sediment) and 29.00 ng/g (fish) for the rainy season while concentrations of 0.170 µg/L (water), 14 ng/g (sediment) and 28.00 ng/g (fish) were obtained for the dry season. 0.05–0.15 ng/g for aldrin, 0.12–5.8 ng/g for dieldrin, 0.22–0.64 ng/g for endrin, 0.24–6.37 ng/g for endosulfan and 0.21–8.81 ng/g for ΣDDT (p, p` -DDD, p, p` -DDE, p, p` -DDT). Among the OCPs, ∑HCH, endosulfan and PDDT were the most dominant compounds in the river sediments. γ- HCH was the most frequent detected compound in all the samples from this river. Among the cyclodiene compounds, aldrin was in abundance in most of the sediments, water and fish samples. γ-HCH, γ-HCH and HCB contributed this highest value for the water, sediment and fish sample respectively in the rainy season while aldrin, endrin and HCB were the highest contributors to the ΣOCPs to the mean of water, sediment and fish respectively. Hazard quotient and bioaccumulation analysis carried out on the fish sample revealed that the fishes were heavily contaminated with values >1 for both seasons which possess a possibility for ecological concern.

Preliminary Studies of Organochlorine Pesticides (OCPs) in Sediment, Water and Fish Samples from Ethiope River, Abraka Axis, Southern Nigeria

Selected persistent organochlorine pollutants, including DDT and its metabolites, hexachlorobenzene, dieldrin, Aldrin, heptachlor, HCH as well as some of their isomers were determined in water, sediment and fish samples from the Ethiope River in Southern Nigeria. Twenty organochlorine pesticides were detected in both seasons from October 2012 – September 2013. Results revealed ∑HCH to be 0.620µg/L (water), 33 ng/g (sediment) and 29.00 ng/g (fish) for the rainy season while concentrations of 0.170 µg/L (water), 14 ng/g (sediment) and 28.00 ng/g (fish) were obtained for the dry season. 0.05–0.15 ng/g for aldrin, 0.12–5.8 ng/g for dieldrin, 0.22–0.64 ng/g for endrin, 0.24–6.37 ng/g for endosulfan and 0.21–8.81 ng/g for ΣDDT (p, p` -DDD, p, p` -DDE, p, p` -DDT). Among the OCPs, ∑HCH, endosulfan and PDDT were the most dominant compounds in the river sediments. γ- HCH was the most frequent detected compound in all the samples from this river. Among the cyclodiene compounds, aldrin was in abundance in most of the sediments, water and fish samples. γ-HCH, γ-HCH and HCB contributed this highest value for the water, sediment and fish sample respectively in the rainy season while aldrin, endrin and HCB were the highest contributors to the ΣOCPs to the mean of water, sediment and fish respectively. Hazard quotient and bioaccumulation analysis carried out on the fish sample revealed that the fishes were heavily contaminated with values >1 for both seasons which possess a possibility for ecological concern.

Nationwide levels and distribution of endosulfan in air, soil, water, and sediment in South Korea

We investigated the levels and distribution patterns of α- and β-endosulfan and endosulfan sulfate in air, soil, water, and sediment samples collected from the South Korean persistent organic pollutants (POPs) monitoring networks. In the air samples, the highest concentrations of the total (Σ₃) endosulfan (50.3-611 pg/m³, mean: 274 pg/m³) were observed during summer. Spearman analysis revealed a good correlation between agricultural land area and atmospheric concentrations of Σ₃ endosulfan except during winter. Regardless of the season, the ratio of the two isomers (α/β) was 3.6-4.9 in the air samples, higher than that observed in technical mixtures (2.0-2.3), possibly due to the higher volatility of α-endosulfan, compared to β-endosulfan. Concentrations of Σ₃ endosulfan in the soil samples (n.d.-13.4 ng/g, mean: 0.8 ng/g) were not significantly different except at some stations adjacent to large areas of farmland. The average levels of Σ₃ endosulfan in the water and sediment samples were 2.1 ng/L and 0.1 ng/g dw, respectively. In analyzing the four largest rivers, it was observed that a few water stations during spring and fall and sediment stations in fall had high concentrations of the two isomers and endosulfan sulfate, particularly around the Yeoungsan and Nakdong Rivers near large areas of agricultural land. Endosulfan sulfate was dominant at most water and sediment sampling stations. This study demonstrates that the endosulfan found in most environmental compartments most probably derives from agricultural areas despite its ban as a pesticide. On the other hand, given that it was also detected in industrial and urban areas, in which pesticide application does not occur, it can be conjectured that endosulfan is aerially transported at higher temperatures and continuously circulates within the environment.

History traces of HCHs and DDTs by groundwater dating and their behaviours and ecological risk in northeast China

Organochlorine pesticides legacies, such as hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT), remained in sediments or soils due to their difficulty in decomposition, especially in the agricultural areas where pesticides were widely used historically. Different from the little disturbed depositional environment of lake, it was difficult for rivers to explore the timing of DDT and HCH inputs through dating sediment cores as records. Based on groundwater dating, this study ascertained the historic pollution of DDT and HCH in Taizi River basin. HCH and DDT residues in groundwater were consistent with the historical production and usage, which increased from the 1950s to the 1980s and declined from the 1980s to the 1990s. Moreover, the partitioning behaviours of HCHs and DDTs in surface water and suspended particulate matter were discussed. It was revealed that β-HCH and o,p'-DDT were more likely to attach to suspended particulate matter than other isomers. Furthermore, species sensitivity distribution curves were generated using 54 toxicity data records to assess the risk of HCHs and DDTs in water and suspended particulate matter. These results indicated that p,p'-DDT in surface water posed a high risk to 95% of the aquatic life in the long run.

Evaluation of effect of hazardous contaminants in areas for the abstraction of drinking water

The lower portion of Taquari River is influenced by compounds from anthropic activities causing concern about the drinking water supplied to cities in the region. The study objective was to investigate the presence of contaminants at drinking water abstraction sites, defining the mutagenic effects of these stressors as an ecosystem quality parameter and its possible effects on human health. Geographic Information System techniques were used to investigate sources of contamination and it was found that agricultural activities predominated with a few medium and high potential pollutant agricultural activities, besides a soil area that was contaminated and undergoing an intervention process. Mutagenic effects were evaluated by Salmonella/microsome assay using TA98, TA97a, TA100, YG1041 and YG1042 strains in the presence and absence of metabolic activation (S9). Mutagenesis found in organic sediment extracts and surface water samples showed the prevalence of direct-acting mutagens at the drinking water abstraction sites. Taquari (Ta032, the sampling points were named according to the initial letters of the river (Ta), followed by the number of kilometers from the mouth) showed the highest mutagenic potency in sediment, while Ta063, at Bom Retiro do Sul, presented it in the water sample. In the Triunfo region (Ta011) there were significant responses in sediment and in water samples. The samples at General Câmara (Ta006) showed the least presence of contaminants. The Allium cepa test applied to sediments in natura showed significant micronucleus induction in Ta032 in accordance with the Salmonella/microssome assay. The test performed on Danio rerio embryos (FET) in the in natura water samples did not present significant responses. Chemical analyses of polycyclic aromatic hydrocarbons and metals already identified as chemical markers in the area indicated a small contribution to the mutagenic potency, calling attention to the fact that other direct-acting pollutants may be present at the drinking water abstraction sites.

The effect of ozonation on the degradation of carbaryl in aqueous solution

The aim of this study is to investigate the synergetic effect of ozonation on ultraviolet irradiation on the degradation of carbaryl (CBL) (1-naphthyl-N-methylcarbamate) in aqueous solutions (40 mg L^-1). The degradation of CBL and the intermediates formed during ozonation were determined by gas chromatography-mass spectrometer. The change in formaldehyde, dissolved oxygen, pH, and total acidity were determined as a function of ozonation time. It was found that the dissolved oxygen and total acidity were increased with the increasing ozonation time but the pH was decreased with the increasing ozonation time. The aliphatic acids formed during ozonation were followed by ion chromatography as a function of ozonation time. It was found that the effect of ozonation is highly effective on the degradation of CBL. The complete degradation of CBL has occurred at 75-second ozonation time. As a consequence of the obtained results the possible degradation pathway was proposed. The results confirmed that ozonation is an effective method for the degradation of CBL.

Blood biomarkers of herbicide, insecticide, and fungicide toxicity to fish-a review

Pesticides are widely used in the world agriculture, and they may adversely affect non-target organisms, including fish. The present 2000-2019 literature review summarizes hematological and blood biochemical effects of various herbicides, insecticides, and fungicides in fish. The observed changes usually indicate anemia and inflammation, as well as hyperglycemia, hypoproteinemia, increase in cortisol concentration and activities of hepatic aminotransferases that are typical for intoxication and stress. Other changes that are also sometimes observed such as increase in red blood parameters indicate compensatory response. The often-noted symptoms of immunosuppression show an adverse effect of pesticides on immune system and possible immunosuppression. Pathophysiological changes in fish induced by pesticides depend on many factors, such as active compound and its concentration, exposure duration, fish species, environmental conditions, etc. Hematological and blood biochemical parameters appear to be useful biomarkers for evaluation of physiological state of fish exposed to pesticides; however, they are not specific markers of intoxication.

Development of pp-LFER and QSPR models for predicting the diffusion coefficients of hydrophobic organic compounds in LDPE

Diffusion coefficient (D) is important to evaluate the performance of passive samplers and to monitor the concentration of chemicals effectively. Herein, we developed a polyparameter linear free energy relationship (pp-LFER) model and a quantitative structure-property relationship (QSPR) model for the prediction of diffusion coefficients of hydrophobic organic contaminants (HOCs) in low density polyethylene (LDPE). A dataset of 120 various chemicals was used to develop both models. The pp-LFER model was developed with two descriptors (V and E) and the statistical parameters of the model showed satisfactory results. As a further exploration of the diffusion behavior of the compounds, a QSPR model with five descriptors (ETA_Alpha, ASP-6, IC1, TDB6r and ATSC2v) was constructed with adjusted determination coefficient (R²) of 0.949 and cross-validation coefficient (Q_Loo²) of 0.941. The regression results indicated that both models had satisfactory goodness-of-fit and robustness. This study proves that pp-LFER and QSPR approaches are available for the prediction of log D values for the hydrophobic organic compounds within the applicability domain.

Occurrence and risk evaluation of organochlorine contaminants in surface water along the course of Swartkops and Sundays River Estuaries, Eastern Cape Province, South Africa

Organochlorine contaminants were analysed in surface water from Sundays (SDE) and Swartkops Estuaries (SWE), Eastern Cape Province, which is among the largest estuaries in South Africa. The concentration of Σ₁₈OCPs ranged from 16.7 to 249.2 ng/L in autumn, 19.9-81.4 ng/L in winter, 43.6-126.8 ng/L in spring and 68.3-199.9 ng/L in summer for SDE, whereas in SWE, the values varied from 20.9 to 259.7 ng/L in autumn, 58.9-263.9 ng/L in winter, 3.2-183.6 ng/L in spring and 118.0-188.9 ng/L in summer. Among all OCPs, α-HCH, β-HCH, p,p'-DDE, p,p'-DDT, endrin, dieldrin and endrin aldehyde were predominant in surface water samples from SDE and SWE. Furthermore, the mean concentration of polychlorinated biphenyls (PCBs) ranged from 126.7 ng/L in winter to 151.0 ng/L in spring for SDE and 249.0 ng/L in spring to 727.6 ng/L in winter for SWE. Tri- and tetra-PCBs dominated the PCB homologue profile. Hierarchical cluster analysis grouped the study sites into three regions from least polluted to most polluted, indicated that SWE is more polluted compared to SDE, probably due to the influx of agricultural and industrial effluents. Carcinogenic and non-carcinogenic risk assessment revealed that the water from both estuaries is not safe for drinking, although suitable for bathing.

Mutagenicity, genotoxicity and oxidative stress induced by pesticide industry wastewater using bacterial and plant bioassays

Atomic absorption spectrophotometer and gas chromatography analysis revealed the presence of heavy metals, organochlorine and organophosphate pesticides in industrial wastewater. XAD, Dichloromethane and n-Hexane extracted wastewater were analysed for genotoxic potential using Ames Salmonella/mammalian microsome test. The XAD concentrated sample displayed remarkable mutagenic activity compared to solvent assisted liquid-liquid extraction. Strain TA98 was found utmost sensitive towards all extracts. Wastewater induced chromosomal aberrations in roots of Allium cepa showed significant (p < 0.05) decrease in mitotic index. Seeds of Vigna radiata germinated on soft agar plates treated with different concentration of wastewater showed significant reduction in germination (52 %), seedling vigor index (76 %), radicle length (56 %), plumule length (47 %), biomass of radicle (64 %) and plumule (57%) at highest wastewater concentration. Propidium iodide stained V. radiata roots showed oxidative stress induced by wastewater under CLS microscopy. Further, genotoxicity of wastewater was confirmed by plasmid nicking assay using pBR322 plasmid.

Chemical oxidation and reduction of hexachlorocyclohexanes: A review

Lindane (γ-hexachlorocyclohexane) and its isomers (HCH) are some of the most common and most easily detected organochlorine pesticides in the environment. The widespread distribution of lindane is due to its use as an insecticide, accompanied by its persistence and bioaccumulation, whereas HCH were disposed of as waste in unmanaged landfills. Unfortunately, certain HCH (especially the most reactive ones: γ- and α-HCH) are harmful to the central nervous system and to reproductive and endocrine systems, therefore development of suitable remediation methods is needed to remove them from contaminated soil and water. This paper provides a short history of the use of lindane and a description of the properties of HCH, as well as their determination methods. The main focus of the paper, however, is a review of oxidative and reductive treatment methods. Although these methods of HCH remediation are popular, there are no review papers summarising their principles, history, advantages and disadvantages. Furthermore, recent advances in the chemical treatment of HCH are discussed and risks concerning these processes are given.

Occurrence, distribution and risk assessment of pesticides in a river-reservoir system

The water environment from river to reservoir has been considered as a hybrid river-reservoir system due to pronounced environmental properties. This study investigated the distribution and potential environmental behavior of pesticides in river-reservoir system, examining 31 target pesticides in water phase from a key drinking water source (Dongjiang River). The concentrations of ∑₈OCPs, ∑₁₆OPPs and ∑₇SPs with the corresponding occurrence were in the range of 107.57-340.35 ng/L (moderate level), 232.65-1197.95 ng/L (moderate level) and 125.23-245.09 ng/L (low level), respectively. Ecological risk assessments indicated that most of the pesticides posed a high level of risk to the aquatic organisms. Moreover, seasonal agricultural application, rainfall and temperature could influence the levels and compositions of ∑₈OCPs, ∑₁₆OPPs and ∑₇SPs in the river system, while seasonal hydrological processes could only influence their compositions in the reservoir system. In the wet season, the levels of ∑₈OCPs and ∑₇SPs decreased from the river system to reservoir system probably via biogeochemical processes, while the level of ∑₁₆OPPs decreased along the environmental gradient probably via dilution process. Additionally, longer hydraulic retention time of the reservoir system could contribute to the biogeochemical processes for OPPs and SPs exported from the river system, but it might fail to facilitate this process for OCPs. Taken together, this study highlighted that the distributions and environmental behavior of pesticides in river-reservoir system varied seasonally from river system to reservoir system.

Residues and sources of organochlorine pesticides in soils of elementary schools and communities in Wenchuan 5.12 Earthquake-affected areas

The disinfectants and pesticides extensively used after Wenchuan 5.12 Earthquake on May 12, 2008 (so-called Wenchuan 5.12 Earthquake), for epidemic prevention purpose can raise great concerns of environmental pollution and potential personal exposure. To investigate the soil pollution caused by the intensive application in earthquake-affected areas, surface soil samples from two elementary schools, two communities and two background areas were collected in Beichuan County and Dujiangyan City once per location in spring and in autumn in 2011 and then analyzed by gas chromatography/mass spectrometry for organochlorine pesticides (OCPs). The results showed serious soil pollution of hexachlorocyclohexanes (HCHs, 0.05-60.05 ng/g) and dichloro-diphenyl-trichloroethane (DDTs, 0.06-35.79 ng/g) in the study areas compared with Wolong Nature Reserve (0.03-0.81 ng/g for HCHs and 0.02-0.40 ng/g for DDTs). The concentrations of most OCPs in soil of Beichuan County (e.g., 0.10-60.05 ng/g for HCHs and 0.17-35.79 ng/g for DDTs) were much higher than those of Dujiangyan City (e.g., 0.05-20.58 ng/g for HCHs and 0.06-10.69 ng/g for DDTs). In Beichuan County, the highest concentrations of HCHs and DDTs were found in the elementary school. In Dujiangyan City, the highest concentrations of HCHs and DDTs were found in the elementary school and the community, respectively. The concentrations of HCHs and DDTs were generally higher in spring than those in autumn. The predominant species (γ-HCH in ∑HCHs and 4,4'-DDT in ∑DDTs) and specific ratios suggested new inputs of lindane and technical DDT in the study areas. Therefore, continuous soil monitoring and possible intervention would be recommended to minimize local residents' exposure to these toxic chemicals.

Pesticides in the rivers and streams of two river basins in northern Greece

The pollution caused by pesticides, and their ecotoxicological implications were investigated in water samples from the Strymonas and Nestos river basins (Northern Greece). Chlorpyrifos was the most frequently detected pesticide in both basins (42 and 37% in the Strymonas and Nestos basins, respectively), followed by fluometuron and terbuthylazine (25 and 12%, Strymonas), and bentazone and boscalid (24 and 10%, Nestos). The Annual Average and the Maximum Allowable Concentration of Environmental Quality Standards set in European Union Directives were exceeded in several cases by alphamethrin and chlorpyrifos. Risk Quotient assessment revealed significant ecological risk towards the aquatic organisms in over 20% of the water samples. Insecticides (mostly pyrethroids and organophosphosphates) contributed more in the ecotoxicological risk than herbicides and fungicides. The three main rivers in the current study (Strymonas, Aggitis, Nestos) exhibited similar sum of RQs indicating that aquatic life in all three of them was at the same risk level. However, the sums of RQs were higher in the various streams monitored than the three rivers.

Polycyclic aromatic hydrocarbons and organochlorine pesticides in surface water from the Yongding River basin, China: Seasonal distribution, source apportionment, and potential risk assessment

The presence of 17 polycyclic aromatic hydrocarbons (PAHs) and 15 persistent organochlorine pesticides (OCPs) in surface water of the Yongding River Basin was analyzed through GC/MS/MS during the spring and summer at 46 sampling sites. The goal was to investigate their seasonal distribution, possible sources, and potential risk. Our results showed that the total PAH concentration in surface water of Yongding River Basin ranged from 41.60 to 1482.60ng/L with a mean value of 137.85ng/L in the spring, and from 53.53 to 506.53ng/L with a mean value of 124.43ng/L in the summer. The total OCP concentration ranged from <0.08 to 197.71ng/L with a mean value of 7.69ng/L in the spring, and from <0.08 to 93.58ng/L with a mean value of 7.92ng/L in the summer. Moreover, the total PAH concentration was slightly lower in the spring than in the summer, whereas the total OCP concentration was similar between seasons. Source analysis indicated that combustion sources and petroleum sources both contributed to the presence of PAHs. Historical environmental residues and long range atmospheric transport were the major sources of HCH and DDT contamination. The concentrations of total PAHs and single PAHs including benz(a)anthracene, benzo(a)pyrene, benz(b)fluoranthene, and benz(k)fluoranthene in surface water at some sampling sites exceeded the water environmental quality standards of China and several other countries or organizations. This indicated a potential threat to human health from the consumption of aquatic organisms due to PAH bioaccumulation. The concentrations of α-HCH, p,p'-DDE, and p,p'-DDD at several sampling sites exceeded the limit for human health specified in the ambient water quality criteria developed by the US Environmental Protection Agency, which indicated that these pollutants provide potential hazards to the residents around the sampling sites.

Risk assessment of an organochlorine pesticide mixture in the surface waters of Qingshitan Reservoir in Southwest China

Risk assessment of single pollutants has been extensively studied. However, the co-exposure of pollutants in a real environment may pose a greater risk than single chemicals. In this study, concentration addition-based risk quotients were applied to the risk assessment of the 15 organochlorine pesticides (OCPs) mixtures (α-hexachlorocyclohexane (HCH), β-HCH, γ-HCH, δ-HCH, heptachlor, aldrin, heptachlor epoxide, chlordane, α-endosulfan, p,p′-dichloro-diphenyl-dichloroethylene, endrin, β-endosulfan, p,p′-dichloro-diphenyl-dichloroethane, p,p′-dichloro-diphenyl-trichloroethane, and methoxychlor) detected in the surface water (reservoirs, ponds, and streams) of Qingshitan Reservoir in Southwest China from 2014 to 2016 by summing up the toxic units (RQ_STU) of the toxicity data from the individual chemicals. The RQ_STU of the OCPs mixture exceeded 1 in 45.23% of the 283 surface water samples based on acute data and an assessment factor of 100, indicating a potential risk for the aquatic environment (fish). Methoxychlor and γ-HCH contributed the most toxicities in the pesticide mixtures toward Daphnia and fish and provided at least 50% of the mixture toxicity in all samples with RQ_STU larger than 1. The most sensitive organism to realistic OCPs mixtures in the surface waters of Qingshitan Reservoir was fish, followed by Daphnia and algae. The values of the maximum cumulative ratio for all samples indicated that the risk assessment based on single chemicals underestimated the pesticide mixture toxicities, which shows that special consideration should be made for the ecological risk of pesticide mixtures in the aquatic environment.

Risk assessment of single pollutants has been extensively studied.

Occurrence of organochlorine pesticides in a tropical lake basin

This study investigates the presence and distribution of organochlorine pesticides in streams and the lake in the Sembrong Lake Basin in Malaysia. The catchment of Sembrong Lake has been converted to agricultural areas over the past 30 years, with oil palm plantations and modern agricultural farming being the main land use. Surface water samples were collected from eight sites comprising the stream and lake and analysed for 19 organochlorine pesticides (OCPs). In situ measurement of temperature, dissolved oxygen, pH and conductivity were also undertaken at each site. Aldrin, endrin, δ-BHC, 4,4-DDT, methoxychlor and endosulfan were the main OCPs detected in the lake basin. The total OCP concentration ranged between 5.42 and 349.2 ng/L. The most frequently detected OCPs were δ-BHC, heptachlor and aldrin. The maximum values detected were 23.0, 43.2 and 50.4 ng/L respectively. The highest concentration of OCPs was attributed to 4,4-DDT, but such high residue was rare and only detected once. Other OCP residues were low. Significant differences in the mean values were observed between lake and stream for dichlorodiphenyldichloroethylene (DDE) and α-endosulfan concentration (p < 0.05). The highest endosulfan, endrin and methoxychlor residues were found in lake sites, while the highest 4,4,-DDT residues were observed for the river sites. Temporal variation of OCP residues was observed for heptachlor and β-endosulfan. The highest concentrations of pesticide residues were found in October. DDX and α/ɣ ratios indicate possible fresh inputs of the OCP pesticide in the basin.

Occurrence and distribution of trifluralin, ethalfluralin, and pendimethalin in soils used for long-term intensive cotton cultivation in central Greece

In the present study, a soil monitoring program was undertaken in Greek cotton cultivated areas in 2012. Twenty-seven soil samples were collected from the entire Thessaly plain in early summer of 2012, corresponding to approximately three months (current use of pendimethalin), up to one year (for the banned ethalfluralin), and three years (for the also banned trifluralin), after the last dinitroaniline application. Low but not negligible levels of dinitroanilines were detected, ranging from 0.01 to 0.21 μg g^-1 d.w. for trifluralin and 0.01-0.048 μg g^-1 d.w. for pendimethalin, respectively. Trifluralin was the herbicide most frequently detected (44.4%). The high historic application of trifluralin and its high persistence and accumulation potential is in line with the abundance of the detected residues. The present data indicate that soil samples contain extractable residues of banned trifluralin, but based on the comparison of the theoretical PECplateau for trifluralin (0.277 µg g^-1) and the maximum Measured Environmental Concentration, it was concluded that the detected residues should be attributed to previous years' application. The latter suggested the need for continual monitoring of the dinitroaniline family of pesticides, including the banned substances, aiming thus to an improved environmental profile for agricultural areas.

Determination of the priority substances regulated by 2000/60/EC and 2008/105/EC Directives in the surface waters supplying water treatment plants of Athens, Greece

An investigation into the occurrence of priority substances regulated by 2000/60/EC Water Framework Directive and 2008/105/EC Directive was conducted for a period of one year in the surface water sources supplying the water treatment plants (WTPs) of Athens and in the raw water of WTPs. Samples from four reservoirs and four water treatment plants of Athens were taken seasonally. The substances are divided into seven specific groups, including eight volatile organic compounds (VOCs), diethylhexylphthalate, four organochlorine pesticides (OCPs), three organophosphorus/organonitrogen pesticides (OPPs/ONPs), four triazines and phenylurea herbicides, pentachlorophenol, and four metals. The aforementioned substances belong to different chemical categories, and different analytical methods were performed for their determination. The results showed that the surface waters that feed the WTPs of Athens are not burdened with significant levels of toxic substances identified as European Union (EU) priority substances. Atrazine, hexachlorocyclohexane, endosulfan, trifluralin, anthracene and 4-nonylphenol were occasionally observed at very low concentrations. Their presence in a limited number of cases could be attributed to waste disposal, agricultural activities, and to a limited industrial activity in the area nearby the water bodies.

Occurrence of organochlorine pesticides from typical water sources in YiXing City, Taihu Upper-River Basin, East China

This is the first report on the occurrence of 18 organochlorine pesticides (OCPs) in YiXing, Taihu Upper-River Basin, East China.

Pesticides in the surface waters of Lake Vistonis Basin, Greece: Occurrence and environmental risk assessment

A study was undertaken for the evaluation of the pesticide pollution caused by the agricultural activities in the basin of Lake Vistonis, Greece during the years 2010-2012. Water samples were collected from Lake Vistonis, four major rivers and various small streams and agriculture drainage canals. The concentration of 302 compounds was determined after solid-phase extraction of the water samples and subsequent LC-MS/MS and GC-MS/MS analysis of the extracts. Overall, herbicides were the most frequently detected pesticides (57%), followed by insecticides (28%) and fungicides (14%). In Lake Vistonis 11 pesticides were detected. Specifically, fluometuron was detected in the 75% of the samples (maximum concentration 0.088 μg/L) whereas lambda-cyhalothrin was detected in all the samples of spring 2011 and alphamethrin in all the samples of spring 2012 (maximum concentration 0.041 and 0.168 μg/L, respectively). In the rivers and drainage canals 68 pesticides were detected. Specifically, fluometuron was detected in the 53% of the samples (maximum concentration 317.6 μg/L) followed by chlorpyrifos and prometryn (16 and 13% of the samples respectively). An environmental risk assessment was performed by employing the Risk Quotient (RQ) method. The risk assessment revealed that at least one pesticide concentration led to a RQ>1 in 20% of the samples. In Lake Vistonis, alphamethrin and lambda-cyhalothrin concentrations resulted in RQ>1, whereas in the other water bodies this was mainly the result of chlorpyrifos-methyl and alphamethrin exposure. In contrast, herbicide and fungicide concentrations contributed substantially less to environmental risks.

Sources, concentrations and risk factors of organochlorine pesticides in soil, water and sediment in the Yellow River estuary

The environmental occurrence, sources and risk factors of organochlorine pesticides (HCHs and DDTs) and their isomers or metabolites were studied using comprehensive surveys (including soil, surface water, groundwater and sediment sampling) conducted in the Yellow River Delta (YRD). HCHs and DDTs were all detected in multi environmental media. Compared with reported organochlorine pesticide values in China and abroad and with related environmental quality standards, the concentrations of HCHs and DDTs were generally at low levels in the YRD. Composition of OCPs (DDT metabolites and HCH isomers) showed that DDTs in the multiple environments of the YRD not only came from residues of dicofol but also from atmospheric deposition, while HCH pollution results from the historical usage of a mixture of technical HCH and lindane. Furthermore, the sum of Excess Lifetime Cancer Risk (∑ELCR) exposure to HCHs exceeded the generally acceptable risk level of 1.0E-06 recommended by the USEPA for carcinogenic chemicals.

A pesticide monitoring survey in rivers and lakes of northern Greece and its human and ecotoxicological risk assessment

A pesticide monitoring study covering the main rivers and lakes of Northern Greece (Macedonia, Thrace and Thessaly) was undertaken. A total of 416 samples were collected over a 1.5-year sampling period (September 1999- February 2001) from six rivers and ten lakes. The water samples were analyzed with an off-line solid phase extraction technique coupled with a gas chromatography ion trap mass spectrometer using an analytical method for 147 pesticides and their metabolites, including organochlorines, organophosphates, triazines, chloroacetanilides, pyrethroids, carbamates, phthalimides and other pesticides (herbicides, insecticides and fungicides). Based on the pesticide survey results, a human health carcinogenic and non-carcinogenic risk assessment was conducted for adults and children. Ecotoxicological risk assessment was also conducted using default endpoint values and the risk quotient method. Results showed that the herbicides metolachlor, prometryn, alachlor and molinate, were the most frequently detected pesticides (29%, 12.5%, 12.5% and 10%, respectively). They also exhibited the highest concentration values, often exceeding 1 μg/L. Chlorpyrifos ethyl was the most frequently detected insecticide (7%). Seasonal variations in measured pesticide concentrations were observed in all rivers and lakes. The highest concentrations were recorded during May-June period, right after pesticide application. Concentrations of six pesticides were above the maximum allowable limit of 0.1 μg/L set for drinking water. Alachlor, atrazine and a-HCH showed unacceptable carcinogenic risk estimates (4.5E-06, 4.6E-06 and 1.3E-04, respectively). Annual average concentrations of chlorpyriphos ethyl (0.031 μg L), dicofol (0.01 μg/L), dieldrin (0.02 μg/L) and endosulfan a (0.065 μg/L) exceeded the EU environmental quality standards. The risk quotient estimates for the insecticides chorpyrifos ethyl, diazinon and parathion methyl and herbicide prometryn were above acceptable risk values. The coupling of monitoring data to probabilistic human and ecotoxicological risk estimates could find use by Greek regulatory authorities, proposing effective pollution management schemes.

A review of photochemical approaches for the treatment of a wide range of pesticides

Pesticides are renowned as some of the most pernicious chemicals known to humankind. Nine out of twelve most hazardous and persistent organic chemicals on planet have been identified as pesticides and their derivatives. Because of their strong recalcitrant nature, it often becomes a difficult task to treat them by conventional approaches. It is well perceived that many factors can interfere with the degradation of pesticides under ambient conditions, e.g., media, light intensity, humic content, and other biological components. However, for the effective treatment of pesticides, photochemical methods are viewed as having clear and perceivable advantages. In this article, we provide a review of the fundamental characteristics of photochemical approaches for pesticide treatment and the factors governing their capacity and potential in such a process.

Isolation and identification of endosulfan-degrading bacteria and evaluation of their bioremediation in kor river, iran

Objectives

Endosulfan is a lipophilic insecticide, which causes severe health issues due to its environmental stability, toxicity, and biological reservation in organisms. It is found in the atmosphere, soil, sediments, surface waters, rain, and food in almost equal proportions. The aim of this study was to isolate and identify endosulfan-degrading bacteria from the Kor River and evaluate the possibility of applying bioremediation in reducing environmental pollution in the desired region.

Methods

Samples of surface sediments and water were collected from three different stations in two seasons (summer and autumn), as these are areas with high agricultural activity. Isolated bacteria were identified by various biochemical tests and morphological characteristics. The amounts of degradation of endosulfan isomers and metabolites produced as a result of biodegradation were then analyzed using gas chromatography/mass spectrometry.

Results

In this study, the following five bacterial genera were able to degrade endosulfan: Klebsiella, Acinetobacter, Alcaligenes, Flavobacterium, and Bacillus. During biodegradation, metabolites of endosulfan diol, endosulfan lactone, and endosulfan ether were also produced, but these had lesser toxicity compared with the original compound (i.e., endosulfan).

Conclusion

The five genera isolated can be used as a biocatalyst for bioremediation of endosulfan.

Occurrence of micropollutants in four major rivers in Korea

There has been an increasing concern in recent years over the presence of numerous micropollutants in river water. Simultaneously, risk assessment of micropollutants has become increasingly important due to their high toxicity. Therefore, the aims of this study were to characterize the levels of micropollutants in rivers, to identify the sources of these pollutants, and to evaluate their risk quotients (RQ) to the ecological system. Monitoring data from 159 sites distributed across four major rivers in Korea were collected from the Ministry of the Environment (KME) reports. Tests were performed to check for the presence of 35 pollutants in river waters, from which 29 pollutants were detected. Organochlorine pesticides (OCPs) occurred most frequently, at low concentrations, whereas volatile organic compounds (VOCs) and phthalates were detected at higher concentrations. Based on this study, it was suggested that the factories near the sampling sites where pollutants were found represent one of the main sources of chemicals. After comparing the industrial activities with the measured pollutants, although the released amounts were not reported, representative intermediate chemicals were found in the river water. The RQs of most VOCs were below one, despite their concentration range being higher, compared with other pollutants. Methyl bromide and di-n-octyl phthalate occurred frequently in the Han River Basin and the Nakdong River Basin, respectively, and their RQs were consistently high, so further studies should focus on their exact emission source in order to reduce ecological risk. The results suggest that it will be necessary to develop methods of risk assessment that are more tailored to the various micropollutants present in river water, in addition to the implementation of water treatment systems to reduce ecological risk.

Distribution, possible sources, and health risk assessment of SVOC pollution in small streams in Pearl River Delta, China

The pollution levels of typical semivolatile organic compounds (SVOCs) consisting of 15 polycyclic aromatic hydrocarbons (PAHs), 20 organic chlorinated pesticides (OCPs), and 15 phthalate esters (PAEs) were investigated in small rivers running through the flourishing cities in Pearl River Delta region, China. The concentrations of ∑15PAHs were 2.0-48 ng/L and 29-1.2 × 10(3) ng/g in the water and sediment samples, respectively. The ∑20OCPs were 6.6-57 ng/L and 9.3-6.0 × 10(2) ng/g in the water and sediment samples, respectively. The concentrations of ∑15PAEs were much higher both in the water and sediments. The partition process of the detected SVOCs between the water and sediment did not reach the equilibrium state at most of the sites when sampling. The combustion of petroleum products and coal was the major source of the detected PAHs. The OCPs were mainly historical residue, whereas the new inputs of dichlorodiphenyltrichloroethane (DDT), chlordane, and endosulfan were possible at several sites. The industrial and domestic sewage were the major source for the PAEs; storm water runoff accelerated the input of PAEs. No chronic risk of the SVOCs was identified by a health risk assessment through daily water consumption, except for the ∑20OCPs that might cause cancer at several sites. Nevertheless, the integrated health risk of the SVOCs should not be neglected and need intensive investigations.

Part I: temporal and spatial distribution of multiclass pesticide residues in lake waters of Northern Greece: application of an optimized SPE-UPLC-MS/MS pretreatment and analytical method

The present work describes the application of an analytical procedure, utilizing ultra performance liquid chromatography (UPLC) coupled with mass spectrometry instrumentation, for the determination of 253 multiclass pesticides, classified in six different groups. Solid phase extraction was applied for the isolation and pre-concentration of target compounds in water samples. Surface waters of the lakes located in Northern Greece (Volvi, Doirani, and Kerkini), were collected in two time periods (fall/winter 2010 and spring/summer 2011) and analyzed, applying the developed analytical methods. Spatial distribution of detected pesticides was visualized using interpolation methods and geographical information systems (GIS). Pesticides with maximum concentrations were amitrole, propoxur, simazine, chlorpyrifos, carbendazim, triazophos, disulfoton-sulfone, pyridaben, sebuthylazine, terbuthylazine, atrazine, atrazine-desethyl, bensulfuron-methyl, metobromuron, metribuzin, rotenone, pyriproxyfen, and rimsulfuron. In Lake Kerkini, mainly carbamates and triazines were determined at elevated concentrations, near the coastal point of the NW side of the lake. Seasonal variations were strong among the applied pesticide classes and determined concentrations, indicating the contribution of pesticide application patterns and rainfall. Lake Doirani exhibited organophosphate pesticides at higher concentrations mainly at coastal points, while triazines emerged as the main pollutant during spring sampling. Lake Volvi exhibited the highest pesticide concentrations, mostly triazines and ureas at the central part of the lake. The occurrence of extreme values and nonconstant seasonal variations indicated that the concentrations were increased disproportionately during the second sampling, as a result of the varying contribution of pollution sources right after the application period. In all cases, the total concentration of pesticides increased during the second sampling period.

Theoretical study of γ-hexachlorocyclohexane and β-hexachlorocyclohexane isomers interaction with surface groups of activated carbon model

Activated carbon (AC) is employed in drinking water purification without almost any knowledge about the adsorption mechanism of persistent organic pollutants (POPs) onto it. Hexachlorocyclohexane (HCH) is an organochlorinated contaminant present in water and soils of banana crops production zones of the Caribbean. The most relevant isomers of HCH are γ-HCH and β-HCH, both with great environmental persistence. A theoretical study of the influence of AC surface groups (SGs) on HCH adsorption is done in order to help to understand the process and may lead to improve the AC selection process. A simplified AC model consisting of naphthalene with a functional group was used to assess the influence of SGs over the adsorption process. The Multiple Minima Hypersurface (MMH) methodology was employed to study γ-HCH and β-HCH interactions with different AC SGs (hydroxyl and carboxyl) under different hydration and pH conditions. The results obtained showed that association of HCH with SGs preferentially occurs between the axial protons of HCH and SG's oxygen atom, and the most favorable interactions occurring with charged SGs. An increase in carboxylic SGs content is proposed to enhance HCH adsorption onto AC under neutral pH conditions. Finally, this work presents an inexpensive computer aided methodology for preselecting activated carbon SGs content for the removal of a given compound.

Residues of selected polychlorinated biphenyls (PCB) and organochlorine pesticides (OCP) in postmortem lungs from Epirus, northwestern Greece

Organochlorine (OC) pesticides and polychlorinated biphenyls (PCB) are compounds characterized as persistent organic pollutants (POP) in the environment. These compounds are monitored globally since they enter the human body and accumulate in tissues, resulting in consequent adverse effects. In this study concentrations of selected OC compounds were determined in human autopsy lungs from Epirus, a relatively restricted region in northwestern Greece. This is the first epidemiologic study from Greece reporting on monitoring of environmental pollutants in human autopsy material. Thirty lungs collected from that number of autopsy cases were analyzed: 19 males and 11 females. The age range was 14-91 yr (mean ± SD = 61.8 ± 22.5 yr). Twenty-two cases (73%) were positive for at least one pollutant and eight cases were negative (27%). PCB were the most abundant class of contaminants, detected in 15 out of the 30 cases (50%). Dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexanes (HCH) were second and third in abundance with 9 (30%) and 8 (27%) positive cases, respectively. The frequency of detection showed a tendency to increase with age of individuals. The patterns of OC found in human autopsy lungs were similar to those reported previously for other human specimens. Our results demonstrated a similar trend in contamination sources and distribution has occurred in western Greece as noted globally.

Spatiotemporal variation and risk assessment of pesticides in water of the lower catchment basin of Acheloos River, Western Greece

A three-year monitoring survey (March 2005-February 2008) was conducted to investigate, on monthly basis, the presence of thirty pesticides belonging to various categories and metabolites, in Acheloos River (Western Greece), one of the most important water resources in Greece. Six sampling stations along the river were established. Water analyses were performed using solid-phase extraction combined with gas chromatography with flame thermionic detector and mass spectrometry. Statistical analysis using one-way ANOVA and Duncan's multiple range test (P < 0.05) was used to compare annual mean concentrations of pesticides, seasonal and spatial distribution. In general, the highest mean concentrations of the pesticides were recorded at the three stations downstream. The greatest average concentrations were determined during spring and summer in agreement with the pesticide application period. The observed lower concentrations after 2006 reflect the land-use change because of the elimination of tobacco, the main cultivation of the area for many decades. The compounds most frequently detected were diazinon (78.6%), DEA (69.3%), and fenthion (52.6%). Environmental risk assessment using risk quotient (RQ) approach showed high risk for six insecticides in 2005 and one in 2007. A compliance with the European Environmental Quality Standards (EQS) was observed for the priority pesticides.

Health Risk Assessment of Organochlorine Pesticides in a Shallow Freshwater Lake, China

Organochlorine pesticides (OCPs) including Hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) in surface water of Lake Baiyangdian were determined to assess the potential health risk when using as drinking water for children and adults. The concentration of HCHs and DDTs in surface water were in the range of 2.74-11.50 ng L-1 and 3.48-16.88 ng L-1, respectively. Compared with similar results reported around the world, the level of OCPs in this study was in the mid-range. The analysis of health risk indicated that risks from OCPs in most part of the lake would not be risky to human health according to the acceptable risk level, while carcinogenic effects caused by α-HCH might occur if drinking water from Nanliuzhuang (NLZ) and Laowangdian (SCD). α-HCH and β-HCH were the dominating factors for carcinogenic and non-carcinogenic risks, respectively. Risks of OCPs for children were much higher than those caused by OCPs for adults.

Occurrence of pesticide residues in Lebanon's water resources

Contamination of water sources by pesticides is one of the most critical environmental problems. The present work is designed to address the occurrence of 67 pesticides in the Lebanese waters. Chemical analysis was performed by a solid-phase extraction followed by a gas chromatography-mass spectrometry using programmed temperature vaporization injection. In drinking water and groundwater samples, organochlorine and organophosphate pesticides were frequently detected with a maximal sum concentration of up to 31.8 ng L(-1). High pesticide ecotoxicological risk was noticed in many surface waters, while this risk was driven mainly by diazinon, chlorpyrifos, fenpropathrin and bifenthrin insecticides.

Gamma radiolytic eradication of methoxychlor in aqueous media: the degradation pathways using HPLC and SPME-GC-MS

The gamma radiation-induced degradation of environmental pollutant methoxychlor in water was investigated. A 60Co gamma radiation source with a dose rate of 372 Gy h−1 was used for gamma irradiation of 1 mg L−1 and 10 mg L−1 methoxychlor in water with a varied absorbed dose of 1–5 kGy. A single step clean up and pre-concentration procedure based on solid phase micro-extraction was optimized. The extent of radiolytic degradation was monitored by reversed phase HPLC-UV and GC-ECD. The trace and ultra trace level degradation products were identified using GC-MS-SPME by comparing their mass spectra with the NIST 98 m mass spectral library. Most of the generated products for 4 kGy dose are substituted chlorophenols. The reaction pathways of these substituted chlorophenols and benzophenone formation are also proposed. However, generated chlorophenols disappeared along with methoxychlor for an absorbed dose of 5 kGy. The attained degradation of methoxychlor is ∼ 95% that reflects the potential use of ionization radiation for wastewater treatment.

Organochlorine pesticides in soil, water and sediment along the Jinjiang River mainstream to Quanzhou Bay, southeast China

Residue levels of organochlorine pesticides (OCPs) in multiple compartments (water, soil and sediment) along the Jinjiang River mainstream to Quanzhou Bay were monitored to elucidate sources and fate. The concentrations of OCPs in surface soil of the watershed of the Jinjiang River (2.44 ± 1.97 ng/g for hexachlorocyclohexanes (HCHs) and 11.4 ± 8.46 ng/g for dichlorodiphenyltrichloroethanes (DDTs)) and the Quanzhou Bay (1.81 ± 2.15 ng/g for HCHs and 9.72 ± 14.66 ng/g for DDTs) were comparable. The concentrations of HCHs and DDTs in dissolved phase were 55-94% for the total HCHs and ten to sixteen percent for the total DDTs in the Jinjiang River. High correlations of OCPs between suspended particulate matter (SPM) and sediment (p<0.01) were found in this study, which demonstrated that OCPs absorbed onto SPM was the major source in the sediment of Quanzhou Bay. The use of lindane was the major source of HCHs in the study region. Dicofol pollution was found in water of the Jinjiang River and sediment of Quanzhou Bay. Based on the sediment quality guidelines, DDTs pose more ecotoxicological risk in environment of the Jinjiang River and Quanzhou Bay.