Organochlorine Pesticides In Water Research Articles

Variation analysis of organochlorine pesticides in waters and sediments from a tropical river

In this paper, it is analyzed the temporal variation of organochlorine pesticides (OCPs) in water and sediments from a river influenced by the activity in an agricultural field in a tropical country during the period 2013-2016. The novelty consists of increasing the studies of concentrations of OCPs in water and sediments of rivers for contributing to establish thresholds of concentrations that allow to protect the biota in soils and waters. The mean values of the OCPs dissolved in water and sorbed on sediments varied as follows: p.p'-DDT (0.001 – 0.022 μg.L-1), (0.1 – 8.24 μg.kg-1), o.p'-DDT (0.001-0.021 μg.L-1), (0.51 – 5.76 μg.kg-1), p.p'-DDD (0.001-0.01 μg.L-1), (0.14 – 1.96 μg.kg-1), p.p'-DDE (0.001-0.027 μg.L-1), (0.52 – 7.32 μg.kg-1), o.p'-DDE (0.001-0.041 μg.L-1), (0.2 – 5.52 μg.kg-1), Aldrin (0.004-0.053 μg.L-1), (0.23 – 8.22 μg.kg-1), Dieldrin (0.001-0.032 μg.L-1), (1.13 – 6.82 μg.kg-1) and Endrin (0.001-0.008 μg.L-1), (1.16 – 7.60 μg.kg-1). The management of OCPs by the activity in the agricultural field is being controlled.

Simultaneous In Situ Extraction and Self-Assembly of Plasmonic Colloidal Gold Superparticles for SERS Detection of Organochlorine Pesticides in Water.

Rapid component separation and reliable surface-enhanced Raman scattering (SERS) detection of organochlorine pesticide (OCP) residues in real water samples remain major challenges because of sample complexity, trace content, and low molecular affinity for a metal surface. Here, we report a novel strategy of simultaneous in situ extraction and fabrication of plasmonic colloidal gold superparticles (AuSPs) to perform rapid SERS detection of OCPs in environmental water. In this protocol, multiple components of OCPs in complex water were facilely diffused into dichloromethane (DCM) microdroplets and specifically bound to octadecylamine-modified gold nanoparticles (Au-ODAs), affording the SERS substrate through self-assembly of the OCP-trapped Au-ODA into AuSPs with the evaporation of DCM. SERS signals of the specifically prepared Au-ODA could be used as an internal standard to calibrate the absolute signal of OCPs, and multiplex detection could be achieved depending on their molecularly narrow Raman peaks. As for simultaneously sensing four kinds of OCPs (4,4'-DDT, α-endosulfan, tetradifon, and chlordane) in water, the established method showed strong anti-interference ability and comparable quantification ranges with a low limit of detection (LOD). The recoveries ranged from 90.20 to 109.4% for OCPs in farmland, river, and fishpond water, indicating that the established AuSP-based platform is reliable and applicable to the detection of OCPs in real water samples.

Solid phase microextraction of organochlorine pesticides in water using MWCNTs-doped polypyrrole coated on steel fiber

The analysis of organochlorine pesticides (OCPs) residues has received an increasing attention in the last decades. Solid-phase microextration (SPME) is a convenient and fast analytical method, which has been widely used for the determination of volatile and semivolatile organic compounds in aqueous samples. The multiwalled carbon nanotubes/polypyrrole composite coating was used for the SPME of OCPs in water samples. The effects of various parameters on the efficiency of SPME process such as extraction time, extraction temperature, ionic strength, desorption time, and desorption temperature were studied. Under optimized conditions, the detection limits for the OCPs varied between 0.051 and 0.39 pg mL-1, the inter-day and intra-day relative standard deviations for various OCPs using a single fiber were 6.5-11.5% and 3.6-11.5, respectively. The linear ranges varied between 0.001 and 1 ng mL-1. The method was successfully applied to the analysis of ground water samples with the recoveries from 86 to 110%.

Determination of organochlorine pesticides in the surface water from Medjerda river, Tunisia

ABSTRACT In recent years there have been growing environmental concern, especially regarding the utilisation and discharge of toxic substances. Many organic pollutants are detected in aquatic ecosystems such as pesticides. Because they are large-scale production and usage, toxicity, bioaccumulation, and persistence in the environment, they cause harmful effects to organisms and human health. The Medjerda River is one among the main rivers in Tunisia and a number of other studies addressed the importance of this river regarding ecology, geochemistry, and sociology. The organochlorine pesticides (OCPs) were investigated in surface water samples from eight sampling sites in the Medjerda River. The extraction of water samples was performed by liquid-liquid extraction with hexane. Gas chromatography coupled to the mass spectrum (GC-MS) was used to perform qualitative and quantitative determinations. The levels of OCPs in water varied between 4.41 ng g−1 and 29.04 ng g−1. The Hexachlorobenzene (HCB) and ∑DDT are the most dominant compounds in different sampling sites. Distribution of HCB, ∑DDT, and other OCPs are different indicating different sources of contamination. The concentrations of OCPs in the water pose no threat to human and aquatic living species.

Polychlorinated biphenyls and organochlorine pesticides in water and sediment from Volturno River, Southern Italy: occurrence, distribution and risk assessment

BackgroundTo assess the Volturno River pollution and its environmental impact on the Tyrrhenian Sea (Central Mediterranean Sea) caused by Polychlorinated biphenyls (PCBs) and Organochlorine pesticides (OCPs), 32 PCBs and aldrin, α-BHC, β-BHC, δ-BHC, γ-BHC (lindane), 4,4′- DDD, 4,4′-DDE, 4,4′-DDT, dieldrin, endosulfan I, endosulfan II, endosulfan sulphate, endrin, heptachlor, heptachlor epoxide (isomer B) and methoxychlor have been selected and were analyzed in three different phases: dissolved phase (DP), suspended particulate matter (SPM) and sediments. PCBs and OCPs were extracted using an SPE column for the DP and glass fiber filter for SPM and sediment samples. Cleaned extracts were analyzed by gas chromatography with electron capture detector (ECD) and mass spectrometry (MS) detector for PCBs and OCPs, respectively.ResultsPollutants discharges of PCBs and OCPs into the sea were calculated in about 106.9 kg year−1 (87.1 kg year−1 of PCBs and 19.7 kg year−1 of OCPs), showing that this river could be a major source of PCBs and OCPs pollution to the Central Mediterranean Sea. Total concentrations of PCBs ranged from 4.1 to 48.0 ng L−1 in water (sum of DP and SPM) and from 4.3 to 64.3 ng g−1 in sediment samples. The concentrations of total organochlorine pesticides (OCPs) obtained in water (sum of DP and SPM) ranged from 0.93 to 8.66 ng L−1 and from 0.52 to 9.89 ng g−1 in sediment samples. Principal component analysis shows that all PCB compounds are more likely to come from surface runoff than an atmospheric deposition.ConclusionThe data show that higher levels of PCBs and OCPs were found in sediment samples than in DP and SPM samples, which are an indication of no fresh inputs of these compounds. Based on our results, unintentionally produced PCBs by industrial processes (and other processes) were considered to be the main sources of PCBs in Volturno River and Estuary sediments. Considering the Sediment Quality Guidelines (SQGs), the Ecological Risk Index (ERI), the Risk Quotient (RQ) and the USEPA Environmental Quality Standards (EQS), the Volturno River and its Estuary would be considered an area in which the integrity is possibly at risk.

DLLME-SFO-GC-MS procedure for the determination of 10 organochlorine pesticides in water and remediation using magnetite nanoparticles.

There exists a high demand for fast, simple, and reliable methodologies for determining the presence of organochlorine pesticides (OCPs) on environmental samples. Moreover, the toxicity and accumulation of potential OCPs in several environments have led to the development of technologies that achieve their removal from contaminated waters. In this study, a novel method combining a dispersive liquid-liquid microextraction procedure based on the solidification of floating organic drop is developed and validated for the extraction, preconcentration, and determination of 10 OCPs: α-BHC, p,p'-DDE, δ-BHC, dieldrin, p,p'-DDT, endosulfan I, endosulfan sulfate, heptachlor, heptachlor epoxide (isomer B), and methoxychlor in water samples. The results show that the calibration curves were linear for all the studied compounds, and the coefficients of correlation higher than 0.99. The variation coefficient for precision and accuracy was lower than 10%, and the accuracy ranged from 93 to 105%. Low limit of detection and limit of quantification values ranging from 0.06-3.00ngmL-1 and 0.20-10ngmL-1 were obtained, respectively. The capability of the proposed method was confirmed using an analysis of the water samples before and after the degradation process; this was achieved by employing nanomaterials, while performing an analysis of 160 real samples that were sourced from a Brazilian river. A cobalt-doped magnetite was applied for the environmental remediation of the studied compounds, and it was verified that the novel material has the potential to be used in environmental remediation with a degradation efficiency exceeding 80% for the majority of the studied compounds.

Spatio-temporal distribution of organochlorine pesticide residues in water and sediments of tropical reservoirs: a case study of Bui Reservoir, Ghana

This study investigated the spatio-temporal distribution of organochlorine pesticides (OCPs) in water and sediments of the Bui Reservoir from June 2017 to May 2018, to provide baseline data for monitoring contamination in the Reservoir. Samples were collected during four seasons reflecting levels of rainfall and from five sites around the Reservoir. Water and sediment samples were subjected to liquid-liquid separation and ultrasonic extraction, respectively. GC-ECD was used to identify and quantify the pesticide residues. Eight OCPs each for water and sediment were detected and their concentrations in water and sediment range from 0.1–4.6 µg l−1 and 1.38–104.86 ng g−1 dry weight, respectively. α-Hexachlorocyclohexane and trans-chlordane dominated with mean concentrations of 3.2 ± 0.08 µg l−1 and 70.91 ± 3.47 ng g−1 dry weight in water and sediment, respectively. There were non-significant differences (p > 0.05) in the spatial distribution of OCPs in water and sediments, but significant differences (p < 0.001) in the temporal distribution of the contaminants in water and sediments, with the wet season samples accounting for the highest concentrations. This indicated that the distribution, behaviour and fate of OCPs the the reservoir have close links with meteorological properties beyond their chemical composition.

Hazard Quotient and Bioaccumulation Assessment of 26 Organochlorine Pesticides in Water, Sediment and Fish (Tilapia zilli) Warri River, Niger Delta Region - Southern Nigeria

A pesticide is any substance or mixture of substances used to destroy, suppress or alter the life cycle of any pest. Organochlorine pesticides (OCPs) have been known to resist biodegradation, persist in the environment and thus can concentrate through food chains and produce a significant magnification that can pose severe toxic risk to human health. Bioaccumulation and concentration levels of 26 Organochlorine Pesticides were assessed in water, sediment and fish samples from the Warri River, Nigeria. Samples were collected across the two predominant seasons - rainy and the dry season. The results obtained reveal the presence of 22 of the investigated 26 OCPs in the dry season whereas 19 were detected in the rainy season. Results obtained revealed p,p’-DDT, γ-HCH, and aldrin as the most predominant pesticides detected in the water samples with concentrations of 0.588; 0.160 and 0.092 μg/L, respectively. γ-HCH, p’-DDD and aldrin (29.00; 23.00 and 22.00 ng/g, respectively) for the sediment samples. The most predominant contaminants in the fish samples were HCB, o,p’-DDT, γ-HCH (60.00; 29.00 and 27.00 ng/g, respectively). The Hazard Quotient (HQ) analysis was carried out on the fish samples collected revealed factors of 1.34 to 3.17 indicating a moderate hazard while the Bioaccumulation Index (BI) was found to be below 1 indicating their suitability for consumption. However, the risk of toxicity and bioaccumulation arising from long-term consumption of the OCP-contaminated fish may still exist.

Virgin (Fe0) and microbially regenerated (Fe2+) iron turning waste for treating chlorinated pesticides in water

This work investigated the applicability of iron turning waste as filtration media for treating mixture of organochlorine pesticides (OCPs) in water and the ability of non-pathogenic bacterium Shewanella oneidensis to regenerate the exhausted iron turning waste for reuse. In batch experiments, 1.5 × 104 mg/L of iron turning waste efficiently removed (≥85%) five out of six pesticides in 200 mL of water (20 μg/L for each pesticide) in 10 min. Increasing the iron dose from 2.5 × 103 to 1.5 × 104 mg/L enhanced the removal of heptachlor, endosulfan, dieldrin, and endrin by 5.7, 13.2, 23.3, and 39.4%, respectively, whereas lindane and dichlorodiphenyltrichloroethane removal was comparable when using 2.5 × 103 and 1.5 × 104 mg/L of iron. Better pesticide removal (except lindane) was achieved when the initial concentration of each pesticide was higher (20 μg/L versus 1 μg/L) in the solution. Acidic pH favored OCPs (except endosulfan) removal. S. oneidensis efficiently reduced 80 ± 5% of dissolved ferric iron (Fe3+) to ferrous iron (Fe2+) in 72 h. Microbially regenerated Fe2+ iron removed all six OCPs in water efficiently (52–91%) and at similar levels as provided by virgin iron turning (38–100%). Lindane, endosulfan, and dieldrin removal increased 4-fold using S. oneidensis regenerated iron compared to exhausted iron.

Distribution and Risk Assessment of OCPs in Surface Water, Sediments, and Fish from Lake Gucheng and Inflow and Outflow Rivers

To investigate the distribution, source, and ecological risk of organochlorine pesticides (OCPs) residues in Lake Gucheng, surface water, sediment, and biological samples were collected from 12 sampling sites of Lake Gucheng and its inlets and outlets during summer and winter, and the concentrations of 19 OCPs were analyzed. The results showed that the concentration (dry weight) of OCPs in Lake Gucheng ranged from 26.74 to 48.12 ng·L-1 in surface water, 9.01 to 35.34 ng·g-1 in sediment, and 13.39 to 124.29 ng·g-1 in organisms. The pollution characteristics of OCPs in surface water showed that the concentration was much higher in summer than in winter, and much higher at inflow and outflow rivers than in farming ponds and the central region of Lake Gucheng; the seasonal pollution characteristics in sediment were not obvious. All 19 kinds of OCPs in water, sediment, and organisms were detected in different degrees, and the dominant contaminants were HCHs and DDTs. α-HCH was the main pollutant at all sites in both surface water and sediment, with 21% to 42% of total HCHs in two seasons. p,p'-DDD was the main pollutant in surface water with 30% to 76% of total DDTs, whereas p,p'-DDT was the main pollutant in sediment with 68% to 93% of total DDTs in two seasons. Source analysis based on ratios of HCHs isomers and DDTs isomers indicated that there was a new input of OCPs under anaerobic conditions in the study area. The ecological risk assessment showed that the OCPs in surface water did not lead to significant health risks, but the OCPs in sediments might pose ecological risks to the Lake Gucheng ecosystem. The organisms were within the acceptable potential carcinogenic risk range.

Organochlorine Pesticides in Callinectes Pallidus (Rochebrune, 1883) and Penaeus Monodon (Fabricius, 1798) from Lagos Lagoon and Badagry Creek, Lagos, Southwest Nigeria

Organochlorine pesticides (OCPs) have been of great concern around the world owing to their chronic toxicity, persistence and bio-accumulation in aquatic organisms. The OCP concentrations were measured in water, sediment and shell fishes (Panaeus monodon and Callinectes pallidus) in Lagos State (Lagos lagoon and Badagry creek), between November 2018 and June 2019. The samples were analyzed for Alpha (HCH), Beta (HCH), Gamma (HCH), Delta (HCH), Heptachlor, Aldrin, Heptachlor epoxide, Gamma chlordane, Endosulfan1 Alpha chlordane, Dieldrin, DDE, DDD, DDT, Endrin, Endosulfan II, Endrin Aldehyde, Endosulfan sulfate, Endrin ketone and Methoxychlor. The detection and determination of the pesticide residues were carried out by Gas chromatography with electron capture detector. The mean concentration of OCPs in water samples ranged from 0.150 ± 0.012µg/l (Alpha HCH) to 147.60 ± 10.810 µg/l (Endosufan II). The level of OCPs in sediment ranged from 0.150 ± 0.012 µg/kg (Alpha HCH) in Lagos lagoon to 243.500 ± 138.000 µg/kg (ppDDT) in Badagry creek. The highest mean concentration of OCPs in water and sediments were recorded in Lagos lagoon. The Concentration for shell fish ranged from 0.250 ± 0.009 µg/kg (Alpha HCH) in Lagos lagoon to 67.380 ± 22.860 µg/kg (Endosulfan II) in Badagry creek for Callinectes pallidus and from 1.310 ± 0.210 µg/kg (alpha HCH) to 143.500 ± 71.892 µg/kg (Eldrin Aldehyde) in Badagry creek for Penaeus monodon. Methoxychlor, Lindane and Aldrin were the commonly detected compounds in all the samples from both water bodies. The results showed that OCP levels in all shellfish samples analyzed were above the maximum acceptable limits of 0.01ppm (10 µg/kg) set by EU and Federal Ministry of Environment for aquatic life protection. The highest value was recorded in Penaeus monodon in Badagry creek. Indicating an urgent need for the monitoring of these pesticide residues in water, commercially important food species and the environment, as this will go a long way towards preventing various environmental and public health hazards.

Spatial variation of organochlorine pesticides and dissolved organic matter in urban closed lakes

Closed lakes located in urban parks act as sinks of organochlorine pesticides (OCPs), which have been used, for decades, as insecticides, herbicides and fungicides. The closed lakes from Bucharest, Romania, are periodically managed to prevent eutrophication and accumulation of pollutants. However, it is not known if these practices reduce or enhance the legacy pollution with OCPs. The aim of this study was to explore the spatial variation of OCPs in closed lakes. The total concentration of OCPs in water and sediments ranged between 0.0176 and 37.1 µg/L, and between 122 to 1,890 ng/g, respectively. The concentrations of OCPs were compared with the consensus-based sediment quality guidelines (SQGs) in order to evaluate the ecological risks of sediments. The highest potential adverse effects were associated with γ-HCH exposure. Periodical draining and dredging of lakes lead to the resuspension of contaminants, increasing pesticide bioavailability and accumulation in sediments. In addition, we observed that fluorescent dissolved organic matter (DOM) might influence the OCPs cycle. The quantity and character of fluorescent DOM can provide further insight into OCPs degradation. Also, this study may help urban planners to determine the state of urban waters and to find the best solution for water management.

Passive Sampling of Persistent Organic Pollutants in Four Coastal Aquatic Systems of Puerto Rico: A Pilot Study.

Little is known about the presence and effects of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in Puerto Rico's waters. Four coastal aquatic systems were investigated using low-density polyethylene passive sampling for PCBs and OCPs in water and its overlying air. The highest total freely dissolved and gaseous concentrations of PCBs were found in Guánica Bay, with 4000pg/L and 270pg/m3, respectively. Five OCPs were detected, mainly in water, with greatest concentrations (pg/L) in Guánica Bay: α-HCH (7400), p,p'-DDE (390), aldrin (2000), dieldrin (420), and endrin (77). The compound α-HCH was also measured at elevated water concentrations in Condado Lagoon (5700pg/L) and Laguna Grande (2900pg/L). Jobos Bay did not show values of concern for these persistence organic pollutants. Levels of PCBs and OCPs in water, particularly in Guánica Bay, exceeded USEPA ambient water quality criteria values representing a human health risk regarding consumption of aquatic organisms.

Toxicity assessment of heavy metals and organochlorine pesticides in freshwater and marine environments, Rosetta area, Egypt using multiple approaches

Egypt faces a rapidly increasing deterioration of its surface water owing to the discharges of contaminated effluents. The present study focuses on assessing the levels of toxic heavy metals and organochlorine pesticides (OCPs) in water, sediments and Phragmites australis of freshwater and marine environments at Rosetta area. Fourteen sites were sampled including 4 sites within the marine environment and 10 sites distributed along the Rosetta River Nile. Potential sources of pollution were spatially assessed using remote sensing and geographic information system techniques. To quantify the environmental impact of metals on the aquatic system, metal index (MI) in freshwater, heavy metal pollution index, and ecological risk index (Er) in sediments as well as bioaccumulation factor (BAF) in P. australis were calculated. Remote sensing results showed that drainage canals (954.8 km), cultivations (1252.4 km2) and urbanized zones (88.6 km2) are the major sources of contamination in the studied area. Results of MI indicated that water of the Rosetta area was moderately affected by the metal pollution. Er values for metals in the investigated sites showed low potential ecological risk (< 40). High values of Er were observed in coastal marine water and the nearby estuary. OCPs in water and sediment samples were below the detection limits. Mean Ni and Co concentrations of metals in P. australis were higher than the critical limits of these ions. Results of BAF and regression analysis recommend using P. australis in remediation of metals from the aquatic system in such settings worldwide. The present study shows that using integrated remote sensing and chemical analyses could provide a regional and cost-effective assessment tool of environmental toxicity in fresh-saline water interface.

Seasonal, Spatial Variation, and Potential Sources of Organochlorine Pesticides in Water and Sediment in the Lower Reaches of the Dong Nai River System in Vietnam.

The goals of the current study were (1) to examine seasonal and spatial variation of selected OCPs concentrations and (2) to identify potential sources of the pollutants in the lower reaches of the Dong Nai River system. Forty-eight water and sediment samples were taken from 12 stations in the dry and rainy seasons to determine the concentrations of dichlorodiphenyltrichloroethane and its metabolites (total DDTs), hexachlorocyclohexane isomers (total HCHs), heptachlor, aldrin, dieldrin, and endrin. The concentrations of total DDTs (0.30), total HCHs (0.29), Aldrin (0.068), heptachlor (0.04,µgL-1) in water, and total DDTs (8.04), total HCHs (4.51), and Aldrin (1.52,µgkg-1) in sediment were significantly higher in the rainy season than in the dry season (0.14, 0.12, 0.008, 0.009 in water and 3.49, 2.29, and 0.4 in sediment, respectively). Cluster analysis grouped 12 sampling stations into 2 groups, of which group 1 (3 stations) had higher concentrations of total DDTs, total HCHs, Aldrin, heptachlor, and dieldrin in both water and sediment than in group 2. Compositional analysis of total DDTs revealed that DDT residue could be decomposed significantly for the past years and that anaerobic decomposition could be predominant. Principal component analysis/factor analysis (PCA/FA) indicated that the potential sources of OCPs in the study stations could come from residential and agricultural areas located in the upper catchment or areas surrounding the studied stations. In short, OCPs concentration in the studies area could depend on seasonal, spatial variation, and transport of OCPs from upper parts or surrounding areas.

Risk assessment of organochlorine pesticides in drinking water source of the Yangtze River

Organochlorine pesticides have been banned for many years, but the residual trace amount of organochlorine in water may still pose ecotoxicological risk. Meanwhile, the potential risk of organochlorine pesticides released from sediments, especially into drinking water sources, is receiving increasing attention. The present study assessed the pollution and potential risk of drinking water sources along the midstream and downstream Yangtze River. Residues of organochlorine pesticides (OCPs) in water, suspended particle matter (SPM), and sediment were evaluated with isotope dilution HRGC/HRMS. The results indicated that OCPs in water, SPM, and sediment ranged in 0.52–92.97 ng/L, 0.10–4.10 ng/L, and 0.038–11.36 ng/g, respectively. The predominant OCPs in water, SPM, and sediment were β-HCH, p,p'-DDE and PeCB. At site Y1, 8, 13, 18, β-HCH has a higher proportion in sediment samples, while, α-HCH has a higher proportion in SPM samples. The industrial use of HCHs in the history was the main HCHs source for most water and sediment samples, which indicated an absence of fresh inputs of industrial HCHs. Meanwhile, the abundance of p,p'-DDE in water, sediment and SPM samples could be attributed to long-term aerobic degradation of DDTs. The values of ffsw of HCHs, DDTs and PeCB indicate the transfer from water to sediment. Risk assessment showed that HCHs and DDTs posed low ecotoxicological risk to the Yangtze River.

Rapid Monitoring of Organochlorine Pesticide Residues in Various Fruit Juices and Water Samples Using Fabric Phase Sorptive Extraction and Gas Chromatography-Mass Spectrometry.

Fabric phase sorptive extraction, an innovative integration of solid phase extraction and solid phase microextraction principles, has been combined with gas chromatography-mass spectrometry for the rapid extraction and determination of nineteen organochlorine pesticides in various fruit juices and water samples. FPSE consolidates the advanced features of sol-gel derived extraction sorbents with the rich surface chemistry of cellulose fabric substrate, which could extract the target analytes directly from the complex sample matrices, substantially simplifying the sample preparation operation. Important FPSE parameters, including sorbent chemistry, extraction time, stirring speed, type and volume of back-extraction solvent, and back-extraction time have been optimized. Calibration curves were obtained in a concentration range of 0.1–500 ng/mL. Under optimum conditions, limits of detection were obtained in a range of 0.007–0.032 ng/mL with satisfactory precision (RSD < 6%). The relative recoveries obtained by spiking organochlorine pesticides in water and selected juice samples were in the range of 91.56–99.83%. The sorbent sol-gel poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) was applied for the extraction and preconcentration of organochlorine pesticides in aqueous and fruit juice samples prior to analysis with gas chromatography-mass spectrometry. The results demonstrated that the present method is simple, rapid, and precise for the determination of organochlorine pesticides in aqueous samples.

Organochlorine pesticide residues in sediment and water from Nairobi River, Kenya: levels, distribution, and ecological risk assessment.

Production and use of most organochlorine pesticides (OCPs) was banned through the Stockholm Convention on persistent organic pollutants. However, appreciable amounts are still detected in the environment due to their persistence, illegal use, and releases from contaminated soils and obsolete stocks. The present study investigated the levels of OCP residues in Nairobi River. Sediment and water samples were collected from three sites along the river and screened for 17 OCPs using gas chromatography electron capture detector (GC-ECD). Mean pesticide residues ranged from 0.01 to 41.9μgkg-1 in sediment and below detection limit to 39.7ngL-1 in water. In sediment α-HCH, β-HCH, γ-HCH, heptachlor epoxide, and p,p'-DDD were detected in all samples, while α-HCH, γ-HCH, δ-HCH, heptachlor epoxide, endosulfan I, and endrin were detected in all water samples. Levels of OCPs in water were below the WHO maximum allowable limits for surface water. However, values higher than the sediment quality guidelines for sediment samples in Racecourse Road Bridge and Outering Road Bridge were reported, thus confirming the toxicity to aquatic organisms. Consequently, as these compounds are known to bio-accumulate in fatty tissues, continued use of the river water poses a health risk to animals and humans.

Optimization and comparison of membrane-protected micro-solid-phase extraction coupled with dispersive liquid-liquid microextraction for organochlorine pesticides using three different sorbents

A micro-solid-phase extraction technique has been developed, for determination of organochlorine pesticides in water media, using gas chromatography-electron capture detector. Response surface methodology was applied to optimize the performance of the extraction technique. Also, the effect of significant experimental parameters (i.e. extraction time, ionic strength, type and volume of the desorption solvent and desorption time) has been studied. Three frequently used solid sorbents; multi-walled carbon nanotube, silica-based C18, and polymeric solid sorbent (LiChrolut® EN), were implemented and independently optimized and the results were compared to find the best extraction setup. A dispersive liquid-liquid extraction procedure was also used to enhance the sensitivity of the method, showing enrichment factors of 14 to 40. The limits of detection of the optimized technique were less than 0.26 μg L−1 (for methoxychlor with C18) and RSD values were between 3.3 and 14.5% at 1 μg L−1. The calibration functions were linear up to 500 μg L−1 with R2 values of more than 0.995, for all sorbents. The figures of merit of the entire procedure showed that each of the studied sorbents could produce satisfactory results in ultra-trace determination organochlorine pesticides in water.

Partition distribution of selected organochlorine pesticides in water, sediment pore water and surface sediment from uMngeni River, KwaZulu-Natal, South Africa

Organochlorine pesticides (OCPs) were analysed in surface water, pore water and surface sediment samples collected from the uMngeni River, which is one of the largest rivers in the province of KwaZulu-Natal, South Africa. Liquid-liquid extraction was used to extract the analytes from water and pore water samples and soxhlet extraction was used to extract sediment samples with subsequent florisil clean-up and gas chromatography-mass spectrometry (GC-MS) analysis. Twelve selected OCPs were analysed and their total concentrations were found to range from 8.04–21.06 ng/mL, 36.06–188.43 ng/mL and 148.17–554.73 ng/g in unfiltered surface water, unfiltered pore water and surface sediment (dry weight (dw)), respectively. The results indicated that the concentrations of these selected pesticides were far higher in sediment (72%) than in pore water (25%) and water (3%). The most polluted sites were Northern Wastewater Treatment influent (NWTI) for water (Σ12 OCP = 19.41 ± 1.43 ng/mL) and Northern Wastewater Treatment effluent (NWTE) for pore water (Σ12 OCP = 166.23 ± 7.16 ng/mL) and sediment (Σ12 OCP = 495.21 ± 32.38 ng/g). The most abundant individual OCPs and their average concentrations in general in the river were p,p′-DDE in unfiltered water (1.62 ±0.22 ng/mL) and unfiltered sediment pore water (17.09 ±7.96 ng/mL), and endrin in surface sediment (55.57 ± 19.01 ng/g, dw).