Pesticides In Surface Water Research Articles

Analysis of organochlorine pesticides in surface water of the Songhua River using magnetoliposomes as adsorbents coupled with GC-MS/MS detection

A simple and effective method based on magnetic separation has been developed for the extraction of organochlorine pesticides (OCPs) from river water samples using magnetoliposomes as adsorbents. This method avoided the time-consuming column passing process of loading large volume samples in traditional SPE through the rapid isolation of magnetoliposomes with an adscititious magnet. Lipid bilayers formed on the surface of Fe3O4 showed great adsorptive tendency towards analytes through hydrophobic interactions, and zwitterions headgroups endowed the outer surface of magnetoliposomes with hydrophilicity to improve the dispersing property of adsorbents in the sample matrix. The target analytes were detected by gas chromatography-tandem mass spectrometry, and the limits of detection obtained are in the range of 0.04–0.35ngL−1. The relative standard deviations of intra- and inter-day are in the range of 2–5% and 4–7%, respectively. The proposed method was employed for analysis of six OCPs in the surface water samples from two cities along the Songhua River in different seasons. Compared with the traditional methods, the proposed method could reduce the consumption of the organic solvent and shorten the sample preparation time.

Spatial and temporal trends and flow dynamics of glyphosate and other pesticides within an agricultural watershed in Argentina

In the present study, we evaluated the spatial and temporal trends of current-use pesticides in surface water and sediments as well as their relationship with hydrological stream dynamics within the agricultural watershed of El Crespo stream (Buenos Aires Province, Argentina). We sampled 2 contrasting sites: site 1 (upstream), surrounded by agricultural lands, and site 2 (downstream), surrounded by natural grasslands. Most of the applied pesticides (glyphosate, 2,4-D, atrazine, tebuconazole, and imidacloprid) were detected at high frequencies in surface water samples at both sites. However, only glyphosate and aminomethylphosphonic acid (AMPA) were present at high concentrations and had a significant spatial-temporal trend. The highest concentrations were found during spring 2014 at site 1, in association with the intense rains that occurred in that season. The fact that glyphosate and AMPA concentrations were higher than the rest of the studied compounds is closely related to the land use within the watershed, as glyphosate was the most applied herbicide during the fallow period of glyphosate-resistant crops (soybean, maize). The pesticide mixture had a significant spatial-temporal trend, reaching the highest levels during storm flow events in spring 2014. The intensive rains in spring 2014 could be the main factor influencing stream hydrology and pesticide behavior at El Crespo watershed. The estimated annual pesticide losses were 3.11 g/ha at site 1 and 0.72 g/ha at site 2. This result indicates that an attenuation process could be decreasing pesticide loads during downstream transport from site 1 to site 2. Environ Toxicol Chem 2017;36:3206-3216. © 2017 SETAC.

Spatial and temporal patterns of pesticide concentrations in streamflow, drainage and runoff in a small Swedish agricultural catchment

A better understanding of the dominant source areas and transport pathways of pesticide losses to surface water is needed for targeting mitigation efforts in a more cost-effective way. To this end, we monitored pesticides in surface water in an agricultural catchment typical of one of the main crop production regions in Sweden. Three small sub-catchments (88–242ha) were selected for water sampling based on a high-resolution digital soil map developed from proximal sensing methods and soil sampling; one sub-catchment had a high proportion of clay soils, another was dominated by coarse sandy soils while the third comprised a mix of soil types. Samples were collected from the stream, from field drains discharging into the stream and from within-field surface runoff during spring and early summer in three consecutive years. These samples were analyzed by LC-MS/MS for 99 compounds, including most of the polar and semi-polar pesticides frequently used in Swedish agriculture. Information on pesticide applications (products, doses and timing) was obtained from annual interviews with the farmers. There were clear and consistent differences in pesticide occurrence in the stream between the three sub-catchments, with both the numbers of detected compounds and concentrations being the largest in the area with a high proportion of clay soils and with very few detections in the sandy sub-catchment. Macropore flow to drains was most likely the dominant loss pathway in the studied area. Many of the compounds that were detected in drainage and stream water samples had not been applied for several years. This suggests that despite the predominant role of fast flow pathways in determining losses to the stream, long-term storage along the transport pathways also occurs, presumably in subsoil horizons where degradation is slow.

Evaluation of the rotating disk sorptive extraction technique with polymeric sorbent for multiresidue determination of pesticides in water by ultra-high-performance liquid chromatography–tandem mass spectrometry

The use of pesticides has been associated with the increase of productivity of crops and control of vectors that cause diseases. However, excessive use of these compounds can cause human health and environmental problems, especially regarding to water resources. In this work, a method for multiresidue determination of 62 pesticides in surface water using the rotating disk sorptive extraction (RDSE) technique for sample preparation and ultra-high-performance liquid chromatography with tandem mass spectrometry (UHPLC–MS/MS) for analysis was optimized and validated. The parameters time and rotational disk velocity for the extraction step, types and amounts of sorbents, sample pH, ionic strength, time and velocity of the rotating disk in the desorption step, as well different desorption solvents were evaluated. The best results were obtained using 50mL of sample, acidified at pH 2.0, and 2.5g of sodium chloride. The selected velocity of rotation in the extraction step was 1600rpm for 80min. Inside the disk cavity, a small amount (20mg) of the polymeric sorbent Oasis® HLB was used. The desorption step was performed immerging the disk in 3mL of methanol and rotating the disk at 1600rpm for 60min. Procedural calibration curves showed linearity between 0.05 or 0.1–2μgL−1, with r2>0.99 for all compounds. The method presented practical limit of quantification of 0.05 or 0.1μgL−1 and suitable accuracy and precision, with recoveries from 70.1 to 119.9% and RSD≤20% for the levels 0.05, 0.1, 0.5 and 2μgL−1. The validated method was applied to surface water samples from different river and residues of atrazine, azoxystrobin, clomazone, difenoconazole, epoxiconazole, propoxur, simazine and tebuconazole were found in the range of 0.06–0.35μgL−1. The results indicate that the proposed method is suitable for the determination of pesticide residues in surface water, allowing an easy and simultaneously preparation of several samples with low material consumption.

Monitoring of 45 pesticides in Lebanese surface water using Polar Organic Chemical Integrative Sampler (POCIS)

The aim of this study is to assess the dissolved concentration of 45 pesticides in the surface waters of the Lebanese Republic using Polar Organic Chemical Integrative Sampler "POCIS". All of the sampling sites are located in the major agricultural land areas in Lebanon. POCIS (n = 3) were deployed at Ibrahim River, Qaraoun Lake and Hasbani River for a duration of 14 days. The total concentration of pesticides ranged from not detected (nd) to 137.66 ng.L-1. Chlorpyrifos, DDE-pp, diazinon and Fenpropathrin were the most abundant compounds. Qaraoun Lake and Hasbani River were found to be more polluted than Ibrahim River, since they receive large amounts of waste water derived from nearby agricultural lands and they had the lowest dilution factor. The aqueous average concentration of the target compounds were estimated using sampling rates obtained from the literature. Comparison between Time Weighed Average concentrations "TWA" using POCIS and spot sampling is presented. Results showed that POCIS TWA concentrations are in agreement with spot sampling concentrations for Ibrahim and Hasbani Rivers. The toxicity of the major detected pesticides on three representative aquatic species (Daphnia magna, Scenedesmus quadricauda and Oncorhynchus mykiss) is also reported.

A multi‐component method to determine pesticides in surface water by liquid‐chromatography tandem quadrupole mass spectrometry

AbstractPesticide pollution of surface water is a major concern in many agricultural catchments The development of rapid and accurate methods for determining pesticide concentrations in water samples is, therefore, important. Here we describe a method for the simultaneous analysis of six pesticides (metaldehyde, quinmerac, carbetamide, metazachlor, propyzamide and pendimethalin) in natural waters by direct aqueous injection with liquid chromatography‐tandem mass spectrometry. The method validation showed good linearity from 0.2 to 50.0 µg/L with correlation coefficients between 0.995 and 0.999. Method accuracy ranged from 84 to 100% and precision Relative standard deviation (RSD) from 4 to 15%. The limits of detection for the targeted pesticides ranged from 0.03 to 0.36 µg/L. No significant matrix effects on quantification were observed (t‐test). The method was tested on water samples from a small arable catchment in eastern England. Peak concentrations for the determinands ranged from 1 to 10 µg/L.

Evaluation of FOCUS surface water pesticide concentration predictions and risk assessment of field-measured pesticide mixtures-a crop-based approach under Mediterranean conditions.

FOCUS models are used in the European regulatory risk assessment (RA) to predict individual pesticide concentrations in edge-of-field surface waters. The scenarios used in higher tier FOCUS simulations were mainly based on Central/North European, and work is needed to underpin the validity of simulated exposure profiles for Mediterranean agroecosystems. In addition, the RA of chemicals are traditionally evaluated on the basis of single substances although freshwater life is generally exposed to a multitude of pesticides. In the present study, we monitored 19 pesticides in surface waters of five locations in the Portuguese 'Lezíria do Tejo' agricultural area. FOCUS step 3 simulations were performed for the South European scenarios to estimate predicted environmental concentrations (PECs). We verified that 44% of the PECs underestimated the measured environmental concentrations (MEC) of the pesticides, showing a non-compliance with the field data. Risk was assessed by comparing the environmental quality standards (EQS) and regulatory acceptable concentrations with their respective MECs. Risk of mixtures was demonstrated in 100% of the samples with insecticides accounting for 60% of the total risk identified. The overall link between the RA and the actual situation in the field must be considerably strengthened, and field studies on pesticide exposure and effects should be carried out to assist the improvement of predictive approaches used for regulatory purposes.

Evaluation of mosquito Culex quinquefasciatus mortality rate in the face of lethal concentration of deltamethrin and diazinon toxins

Abstract Because of huge consumption for agricultural purpose, presence of pesticides in surface waters of Golestan province (north east of Iran) is very common. These pesticides finally could be stored in aquatic ecosystems and have proven toxic effects on aquatic animals. Culex quinquefasciatus is one of the most common aquatic insects living mainly in the wetlands. The aim of this study was to determine the acute toxicity of deltamethrin and diazinon as potentially perilous organic pesticides and to assess mortality effects of these chemicals on the mosquito Culex quinquefasciatus in the form of LC50.

Seasonal Pollution Characteristics and Source Identification of Polycyclic Aromatic Hydrocarbons and Organochlorine Pesticides in Surface Water of Baiyangdian Lake

Seasonal variations of 17 polycyclic aromatic hydrocarbons(PAHs) and 15 persistent organochlorine pesticides(OCPs) were analyzed during spring and summer in surface water from 12 sampling sites of Baiyangdian lake to elucidate their seasonal pollution characteristics and sources. The results showed that total concentrations of PAHs in surface water of Baiyangdian lake ranged from 35.38 to 88.06 ng·L-1(46.57 ng·L-1 in average) in spring and 25.64 to 301.41 ng·L-1(76.23 ng·L-1 in average) in summer, respectively, and total concentrations of OCPs ranged from 0.69 to 4.50 ng·L-1(1.77 ng·L-1 in average) in spring and 0.11 to 3.20 ng·L-1(0.90 ng·L-1 in average) in summer, respectively. Seasonal pollution characteristics of PAHs in surface water during two different seasons showed that the total concentration of PAHs was much higher in summer than in spring at three sampling sites of Baiyangdian lake including Qiantang, Guancheng and Anxin bridge, and the level of PAHs in spring was much higher than that in summer at the other nine sites. While seasonal pollution characteristics of OCPs showed that the total concentration of OCPs was much higher in summer than in spring in samples of Guancheng sites, and the level of OCPs in spring was slightly higher than that in summer in the rest of samples. From the perspective of spatial and temporal variations in the composition patterns of PAHs and OCPs in surface water of Baiyangdian lake, PAHs were predominated by 3-ring PAHs with 45.92% and 61.36%(52.60% in average) of total PAHs in spring, while in summer Nap was the chief component of 2-ring PAHs in three sampling sites including Qiantang, Guancheng and Anxin bridge with 84.91%, 91.04% and 78.10% of the total, respectively, and 3-ring PAHs were primary pollutants in the other nine sites with 37.14% to 53.90%(48.94% in average) of the total. Residues of HCHs and DDTs were detected in different degrees and β-HCH was the main pollutant at all sampling sites with 29.94% and 100%(59.87% in average) of total HCHs in spring, while β-HCH was the predominant compounds at five sampling sites with 57.55% and 80.23%(61.98% in average) in summer and α-HCHs and δ-HCH were abundant at other sampling sites. Source analysis based on isomer ratios indicated that the main source of PAHs in Baiyangdian lake originated from combustion sources, and additional sources for several sampling sites could be petroleum processes. Ratios of HCH isomers and DDT congeners confirmed that environmental historical residues and long range atmospheric transport were the major sources of OCPs contamination in the study area. Compared with the water quality standard of China and other countries or organizations, concentrations of PAHs and OCPs in surface water of Baiyangdian lake did not exceed the target values of the standard. However, the concentrations of α-HCH and p,p'-DDD in Anxin bridge and Quantou sites exceeded the limit of human health ambient water quality criteria developed by EPA, which reflected that α-HCH and p,p'-DDD would have a potential hazards risk to the residents from Baiyangdian district.

Occurrence and fate of pesticides in the Argentine stretch of the Paraguay-Paraná basin.

The Argentine stretch of the del Plata basin crosses regions devoted to extensive and intensive agriculture mostly with chemical pest control. The utilization of pesticides in the region has increased 900% in the last two decades associated with the introduction of biotech crops and direct-seeding techniques. Our objective was to study the occurrence, concentration, and fate of pesticides in surface water and bottom sediments of the principal tributaries and main watercourse of the Paraguay-Paraná River. We sampled 22 sites in the distal positions of the main affluents and main watercourse of the Paraná and report here results from two monitoring campaigns (2010-2012). Surface water and bottom sediments were analyzed according to standardized methods by matrix-solid-phase dispersion and liquid-liquid extraction, respectively. Twenty-three pesticide compounds were analyzed by gas chromatography. The results from both campaigns indicated a generalized but variable distribution in the concentrations detected throughout the basin. The ranges of total measured pesticide concentrations in water and sediments were, respectively, 0.004-6.62μg/l and 0.16-221.3μg/kg dry weight. Endosulfans, cypermethrin, and chlorpyrifos were ubiquitous compounds in both environmental compartments and quantitatively the most relevant. All concentrations detected in water were over the recommended guidelines for the protection of aquatic biota. The partitioning indicated a higher affinity for the sediments. Agricultural activity is the source of pesticide-pollution loads, transported by tributaries that reach the main watercourse and alter the quality of the aquatic ecosystem.

The influence of particles on bioavailability and toxicity of pesticides in surface water.

Environmental risk assessment is an essential part of the approval process for pesticides. Exposure concentrations are compared with ecotoxicological data obtained from standardized laboratory studies and, if available, from field studies to determine the risk of a substance or formulation for aquatic communities. Predicted concentrations in surface waters are derived using, for example, the European FOrum for the Co-ordination of pesticide fate models and their USe (FOCUS) or the German Exposit models, which distinguish between exposure to dissolved and particle-associated pesticide concentrations, because the dissolved concentration is thought to be the best predictor of bioavailability and toxicity. Water and particle-associated concentrations are estimated based on the organic carbon-water partitioning coefficient (KOC ). This review summarizes published information on the influence of natural suspended solids on bioavailability and toxicity of pesticides to aquatic organisms (algae, invertebrates and fish), and the value of log KOC and log KOW (octanol-water coefficient) as sole predictors of the bioavailable fraction is discussed. The information showed that: 1) the quality and origin of suspended solids played an important role in influencing pesticide bioavailability and toxicity; 2) a decrease in toxicity due to the presence of suspended solids was shown only for pyrethroid insecticides with log KOW greater than 5, but the extent of this reduction depended on particle concentration and size, and potentially also on the ecotoxicological endpoint; 3) for pesticides with a log KOW less than 3 (e.g., triazines, carbamates, and organophosphates), the impact of particles on bioavailability and toxicity is small and species dependent; and 4) pesticide bioavailability is greatly influenced by the test species and their physiology (e.g., feeding behavior or digestion). We conclude that exposure of aquatic organisms to pesticides and environmental risk of many pesticides might be underestimated in prospective risk assessment, when predicted environmental concentration is estimated based on the KOC of a compound. Integr Environ Assess Manag 2017;13:585-600. © 2016 SETAC.

Residues of organochlorine pesticides in surface water of a megacity in central China: seasonal-spatial distribution and fate in Wuhan.

Surface water quality closely correlating with human health suffered increasing organochlorine pesticide (OCP) pollution due to the intensive anthropogenic activities in megacities. In the present study, 112 water samples collected from 14 lakes and 11 drinking water source sites in Wuhan were detected for the residues of OCPs in November 2013 and July 2014, respectively. The ΣOCPs ranged from 5.61 to 13.62ngL-1 in summer with the maximum value in Yezhi Lake and 3.18 to 7.73ngL-1 in winter with the highest concentration in Yandong Lake. Except dichlorodiphenyltrichloroethanes (DDTs), OCP concentrations in summer were significantly higher than those in winter mostly due to the non-point source pollution including land runoff in summer. Source apportionment of hexachlorocyclohexanes (HCHs) and DDTs revealed the historical use of technical HCH and lindane and the new input of DDT, respectively. The spatial distribution of OCPs was not uniform in the surface water of Wuhan because of the significant influence of land development and fishery. The risk assessments showed the heptachlor, and heptachlor epoxide in most sampling sites exceeded the threshold set by the European Union, indicating the possible adverse effects for aquatic lives. Negligible non-carcinogenic risks for drinking and bathing as well as carcinogenic risks for bathing were found in the surface water. However, the total carcinogenic risks of all OCPs (∑Rs) caused by drinking in summer were higher than the safe level of 10-7 in all sampling sites. It was implied that the surface water in Wuhan was not safe for directly drinking without effective purification.

Surface Water Organophosphorus Pesticides Concentration and Distribution in the Langat River, Selangor, Malaysia

Pesticide contamination in the environment is a contemporary global issue. As agricultural production through crop planting in Malaysia now supports both energy and food productions, the concentration and distribution of pesticides in surface water may have changed. Therefore, this study assesses the concentration and distribution of organophosphorus pesticides (quinalphos, diazinon and chlorpyrifos) contamination in the Langat River, Selangor. The Langat River Basin is one of the most populated river basins in Malaysia. As a result, it is surrounded by various environmental stresses of which agricultural activity is a dominant cause. An analytical method has been developed and optimised based on solid-phase extraction and high-performance liquid chromatography, coupled with a diode array detector (SPE–HPLC–DAD). This method allowed for the determination and quantification of selected organophosphorus pesticides. The optimised method displays a high mean recovery for both quinalphos and diazinon (100.21 and 100.15 %, respectively) but relatively low recovery for chlorpyrifos (32.40 %). The low recovery of chlorpyrifos is due to limitations in the determination of multi-residues in a single analytical run, optimisation of chromatographic conditions and the recovery of each compound. The method detection limit was found to be 0.003 μg/L for quinalphos and diazinon, and 0.006 μg/L for chlorpyrifos. Sample analyses revealed the occurrence of quinalphos, diazinon and chlorpyrifos in the Langat River with chlorpyrifos found to have the highest mean concentration of 0.0202 μg/L. The quinalphos and diazinon sample concentrations were 0.0178 μg/L and 0.0094 μg/L, respectively. The concentrations of organophosphorus pesticides in this monitoring study were found to be below the Maximum Contaminant Levels (MCLs) established under the European Union (Drinking Water) Regulation 2014. This study was the first to detect concentrations of quinalphos and diazinon in the Langat River, Selangor.

Pesticides in surface waters: a comparison with regulatory acceptable concentrations (RACs) determined in the authorization process and consideration for regulation.

BackgroundChemical analysis of surface water conducted in European countries indicates that pesticides are often detected in surface waters. This asks regulatory authorities to consider these monitoring data while re-evaluating pesticide approval and setting appropriate risk mitigation measures. During the years 2005–2012, the cantons in Switzerland performed 345,000 pesticide measurements in surface waters. Overall, 203 approved pesticides were examined. For 60 of these substances, regulatory acceptable concentrations (RACs) were published, which were determined from ecotoxicological data in accordance with international test methods within the framework of the authorization procedure.ResultsFor 73 % of the 60 evaluated pesticides, the monitoring data demonstrated that no exceedance of the RAC in surface waters was found. For the 16 remaining compounds, measured environmental concentrations (MECs) were exceeding the RAC value at some sampling sites. However, the 95 percentile of the MECs of all substances analyzed were below the respective RACs. Due to the classification system of surface waters in Switzerland, it became obvious that exceedances of the RAC value occurred in small to medium surface waters. Based on these monitoring data, it can be concluded that mainly herbicides and fungicides were exceeding the RAC; for insecticides only one exceedance was determined. The findings demonstrate that in principle the pesticides are safely used. Most of the exceedances were measured in a surface water surrounded by vineyards in the canton Geneva. Therefore, risk mitigation measures were locally implemented to reduce the entry of pesticides.ConclusionsResults suggest that a few pesticides in use might account for most of the concern for aquatic life. These pesticides with exceedances of the ecotoxicological thresholds are checked for a possible regulatory action. Implementing further risk mitigation measures might be advisable to reduce the exposure in aquatic systems. This evaluation is an ongoing process. When further RAC values are available, currently Switzerland is re-evaluating authorized pesticides, monitoring data can be evaluated accordingly.

Influence of the drying step within disk-based solid-phase extraction both on the recovery and the limit of quantification of organochlorine pesticides in surface waters including suspended particulate matter

In this study, 21 organochlorine pesticides (OCPs) were determined based on sample preparation using solid-phase extraction disks (SPE disks) coupled with programmable temperature vaporizer (PTV)—large-volume injection gas–chromatography mass spectrometry (LVI-GC–MS). The work includes a comprehensive testing scheme on the suitability of the method for routine analysis of surface and drinking water including suspended particulate matter (SPM) with regard to requirements derived from the European Water Framework Directive (WFD, Directive 2000/60/EC). SPM is an important reservoir for OCPs, which contributes to the transport of these compounds in the aquatic environment. To achieve the detection limits required by the WFD, a high pre-concentration factor during sample preparation is necessary, which was achieved by disk SPE in this study. The performance of disk SPE is strongly influenced by the drying step, which could be significantly improved by effective elimination of the residual water by combination of a high vacuum pump and a low humidity atmosphere. Detection limits of the WFD in the ng/L range were achieved by large volume injection of 100μL sample extract. The recoveries ranged from 82% to 117% with an RSD smaller than 13%. The applicability of this method to natural samples was tested for instrumental qualification and system suitability evaluation. Successful participation in an interlaboratory comparison proved the suitability of the method for routine analysis.

Examining impacts of current-use pesticides in Southern Ontario using in situ exposures of the amphipod Hyalella azteca.

In situ exposures with Hyalella azteca were used to assess impacts of current-use pesticides in Southern Ontario, Canada. Exposures were conducted over 2 growing seasons within areas of high pesticide use: 1 site on Prudhomme Creek and 3 sites on Twenty Mile Creek. Three sites on Spencer Creek, an area of low pesticide use, were added in the second season. Surface water samples were collected every 2 wk to 3 wk and analyzed for a suite of pesticides. Hyalella were exposed in situ for 1 wk every 4 wk to 6 wk, and survival and acetylcholinesterase (AChE) activity were measured. Pesticides in surface waters reflected seasonal use patterns: lower concentrations in spring and fall and higher concentrations during summer months. Organophosphate insecticides (chlorpyrifos, azinphos methyl, diazinon) and acid herbicides (2,4-dichlorophenoxyacetic acid [2,4-D], mecoprop) were routinely detected in Prudhomme Creek, whereas neutral herbicides (atrazine, metolachlor) dominated the pesticide signature of Twenty Mile Creek. Spencer Creek contained fewer pesticides, which were measured at lower concentrations. In situ effects also followed seasonal patterns: higher survival and AChE activity in spring and fall, and lower survival and AChE activity during summer months. The highest toxicity was observed at Prudhomme Creek and was primarily associated with organophosphates. The present study demonstrated that current-use pesticides in Southern Ontario were linked to in situ effects and identified sites of concern requiring further investigation.

Human Health Risk Associated with Dietary and Non-Dietary Intake of Organochlorine Pesticide Residues from Rice Fields in Edo State Nigeria

The levels, distribution patterns, ecological risk and human health risk of fourteen organochlorine pesticides in surface water, sediment, and fish (Tilapia zilli and Clarias gariepinus) collected from a massive rice field in Illushi, were monitored. Samples obtained were extracted and analyzed using gas chromatography equipped with electron capture detector while risk assessment was carried out using standard models (risk quotient and Chronic daily intake). Pesticide concentration in water samples ranged from ND to 1.65 µg/l, while the concentration of pesticide residues in sediment, C. gariepinus, and T. zilli ranged from ND to 8.45 µg/kg dw, 0.03 to 1.57 µg/kg/ww, and 0.03 to 0.85 µg/kg/ww, respectively. There was a clear dominance of the organochlorine; Hexachlorocyclohexane (α-HCH, γ-HCH, β-HCH) in all matrices. Risk quotient estimates for heptachlor, heptachlor epoxide, aldrin, dieldrin, DDT, endosulfan I, endosulfan II, and endosulfan aldehyde showed risk to aquatic organisms under extreme conditions. Health risk estimations showed that there is a potential risk to humans exposed to contaminated water, sediment, and fishes through ingestion, inhalation, and dermal routes of exposures. Cumulative hazard quotient estimated for pesticide mixtures in each matrix further confirmed that there was potential risk to human health especially children. Furthermore, the risk of non-carcinogenic effects followed the following sequence; biota > sediment > water. This study presents evidence of the multiple contamination of water, sediment, and biota from the Illushi River Basin which would possibly lead to non-cancer effects in humans especially children when exposed. Therefore, water bodies draining agricultural farmlands should be monitored regularly to prevent the contamination of the aquatic environment by toxic and banned pesticides, while efforts should be intensified to regulate the sales, application, and disposal of pesticide products in Nigeria.

Occurrence and seasonal loads of pesticides in surface water and suspended particulate matter from a wetland of worldwide interest--the Ria Formosa Lagoon, Portugal.

Two novel methods were developed to extract and quantify 56 pesticides in surface waters, considering their content in both dissolved aqueous phase (DAP) and suspended particulate matter (SPM) fractions. These procedures were applied to coastal samples taken seasonally during 2012-2013, from three strategic sampling sites along the Ria Formosa Lagoon (south of Portugal). Briefly, 500 mL of water samples were filtrated, separating both fractions. The DAP fraction was extracted and pre-concentrated by solid-phase extraction (SPE), while the SPM was extracted using ultrasonic extraction technique (USE). Both fractions were then analyzed, and the pesticides were quantified and identified, within 35 min, by gas chromatography (GC) coupled to mass spectrometry (GC-MS and GC-MS/MS), respectively. The extraction of pesticides from the SPM fraction showed average recoveries of 102%, detection limits below 2.2 ng/L, and quantification limits ranging from 0.3 to 6.6 ng/L. Considering the real water samples, 73% of the selected pesticides were quantified in both DAP and SPM fractions (ΣDAP+SPM 2.3 μg/L) and their maximum levels were measured in autumn and winter. By category, the global loads of fungicides, herbicides, and insecticides were ≈407, ≈323, and ≈1.6 μg/L, respectively. Thirty-one percent of the quantified pesticides exceeded the European directives levels (2008/105/EC and 98/83/EC). From the total loads, the SPM fraction contribution was 32%, showing the importance of measuring pesticides in that fraction. The water physicochemical parameters revealed that the total nitrogen amounts were very high relatively to the legal required values, mainly close to the city of Faro (2.6 mg/L). In light of the above, measures are in need to meet European directives and protect both fauna and humans that use this area for leisure.

Development of passive sampler POCIS for the analysis of polar pesticides in surface water

The first time in Vietnam a passive sampling method has been developed to analyse the polar pesticides in surface water. The initial investigations of POCIS were performed for 7 polar pesticides as simazine,thiodicarb, carbofuran, chlortoluron, atrazine, isoproturon, and diuron. We determined the sampling rates RS for these substances ranged from 0.369 to 0.962 L day- 1. The obtained values of ku and RS showed the important influence of environmental factors such as flow on the ability to integrate polar pesticides in passive sampling process. This method can be applied to determine these 7 polar pesticides in surface water at trace levels according to European standards for pesticide residues in water (< 0.1 μg L-1).

Multi-residue analysis of polar pesticides in surface water and sediment by high performance liquid chromatography

We have successfully studied the analytical method of polar pesticides like carbofuran, pirimicarb, thiodicarb, atrazine, simazine, carbaryl, diuron, isoprocarb in surface water and sediment by HPLC-UV. The method could be applied to HPLC- MS. The stable recoveries ranged from 79 – 110 % with surface water and sediment samples. Especially, a cleanup procedure combined QuEChERS method and solid phase extraction has been developed to analyse these compounds in sediment, a very complex matrix.