Concentrations Of Dieldrin Research Articles

Quantitative measures of recent and lifetime agricultural pesticide use are associated with increased pesticide concentrations in house dust

ObjectiveElevated pesticide concentrations have been found in dust from homes with residents who use agricultural pesticides, but few studies have compared these concentrations to quantitative measures of their use. We evaluated household pesticide dust concentrations in relation to quantitative, active ingredient-specific metrics of agricultural pesticide use in the Biomarkers of Exposure and Effect in Agriculture Study. MethodsParticipants provided vacuum dust samples (2013–2018) and information regarding recent (last 12 months) and lifetime pesticide use. Thirty-two pesticide analytes were measured in 295 dust samples from 213 participants; 54 had repeated measurements (median = 96 days between visits). We used mixed-effects quantile regression models to estimate relative differences in pesticide concentrations for recent and lifetime agricultural use (number of days, intensity-weighted days), recent home/garden use (yes/no), and household characteristics. Only household characteristics were examined for dacthal because of no use information. We calculated intraclass correlation coefficients (ICCs) to evaluate temporal variability. We report only descriptive statistics for pesticides with detection rates <25 %. ResultsFor currently used pesticides, quantitative measures of recent agricultural use were associated with significantly increased household pesticide dust concentrations for malathion, metolachlor, acetochlor, cyfluthrin, and atrazine (p-trends < 0.001), but not permethrin. Similarly, quantitative measures of lifetime use were associated with increased concentrations of malathion, metolachlor, carbaryl, diazinon, and atrazine (p-trends < 0.001), but not permethrin, chlorpyrifos, or chlorothalonil. For banned pesticides, ever agricultural use was associated with elevated chlordane and heptachlor concentrations and non-significantly elevated dieldrin concentrations, but not lindane, p,p-DDD, p,p-DDE, or p,p-DDT. Recent home/garden use predicted increased malathion, carbaryl, and cyfluthrin concentrations. ICCs (range = 0.57–0.90) suggested moderate to high correlation over 3–6 months. Detection rates were <25 % for alachlor, butylate, EPTC, metribuzin, simazine, carbofuran, coumaphos, as well as for three banned pesticides (cyanazine, aldrin, endosulfan). ConclusionsHousehold pesticide dust concentrations were strongly associated with the frequency of agricultural pesticide use.

Dieldrin accumulation, distribution in plant parts and phytoextraction potential for several plant species and Cucurbita pepo varieties

Dieldrin, an organochlorine pesticide (OCP) widely used for crop protection in the second half of the 20th century till the 70's, is worldwide still present in arable soils. It can be transferred to crops, notably cucurbits, depending on plant species and cultivars. Finding strategies to decrease OCP bioavailability in soil is therefore a main concern. Phytomanagement strategies could provide (i) ready-to-use short term solution for maintaining the production of edible plant parts with dieldrin concentrations below the Maximum Residue Limits (MRL) and (ii) long-term solution for dieldrin phytoextraction reducing progressively its bioavailability in the soil. This field study aimed at determining dieldrin accumulation capacities and allocation pattern in 17 non-Cucurbitaceae species and 10 Cucurbita pepo varieties, and assessing the dieldrin phytoextraction potential of these plant species when grown to maturity in a historically dieldrin-contaminated soil. Out of the non-Cucurbitaceae species, vetiver was the only one able to accumulate significant amounts of dieldrin, which mainly remained in its roots. All C. pepo varieties were able to uptake and translocate high dieldrin amounts into the shoots, leading to the highest phytoextraction potential. Despite the intraspecific variability in dieldrin concentration in zucchini plant parts, mainly in the reproductive organs, the phytoextraction capacity for shoots and fruits was high for all tested varieties (147 to 275 μg dieldrin plant−1, corresponding to 5.6 % of the n-heptane extractable soil dieldrin), even for the one with low fruit dieldrin concentration. Both food safety and phytoextraction could be achieved by selecting productive zucchini varieties displaying low dieldrin concentration in fruits and high one in shoots.

Optimization of Dieldrin Selection for the Genetic Sexing of Aedes albopictus.

The mass production of mosquitoes at an industrial scale requires efficient sex separation, which can be achieved through mechanical, genetic or artificial intelligence means. Compared with other methods, the genetic sexing approach offers the advantage of limiting costs and space by removing females at the larval stage. We recently developed a Genetic Sexing Strain (GSS) in Aedes albopictus based on the sex linkage of the rdlR allele, conferring resistance to dieldrin, to the male (M) locus. It has been previously reported that dieldrin ingested by larvae can be detected in adults and bioaccumulated in predators, raising the question of its use at a large scale. In this context, we performed several experiments aiming at optimizing dieldrin selection by decreasing both dieldrin concentration and exposure time while maintaining a stable percentage of contaminating females averaging 1%. We showed that the previously used dieldrin exposure induced an important toxicity as it killed 60% of resistant males at the larval stage. We lowered this toxicity by reducing the dose and/or the exposure time to recover nearly all resistant males. We then quantified the residues of dieldrin in resistant male adults and showed that dieldrin toxicity in larvae was positively correlated with dieldrin concentrations detected in adults. Interestingly, we showed that the use of reduced dieldrin exposure led to a dieldrin quantification in adult males that was below the quantity threshold of the Gas Chromatography-Mass Spectrometry detection method. Presented data show that dieldrin exposure can be adjusted to suppress toxicity in males while achieving efficient sexing and lowering the levels of dieldrin residues in adults to barely quantifiable levels.

Organochlorine pesticide exposures, metabolic enzyme genetic polymorphisms and semen quality parameters among men attending an infertility clinic.

The associations of organochlorine pesticides (OCPs) with semen quality from human studies are conflicting, and also it is largely unknown whether the associations are modified by genetic polymorphisms. We aimed to evaluate the associations between serum concentrations of 18 OCPs and semen quality among 387 Chinese men, and further to examine the modifying effects by genetic polymorphisms in cytochrome P450 (CYP2E1) and glutathione S-transferase (GSTT1). Multivariable linear regressions were used to evaluate the relationships between serum OCP concentrations and semen quality, and the role of CYP2E1 and GSTT1 polymorphisms in modifying the associations were assessed. Multiple testing was adjusted using the false discovery rate (FDR). We observed that men with detectable concentrations of serum ɤ-HCH had a decrease in sperm motility of 7.07% (95% CI: -10.9%, -3.24%) compared to those with undetectable concentrations (FDR-P value=0.02). Men with TT of CYP2E1 rs 915906 genotypes had higher median concentrations of serum dieldrin compared with those with CT/CC of CYP2E1 rs 915906 genotypes. There were interactions between CYP2E1 and GSTT1 polymorphisms and certain OCPs namely ɤ-HCH, δ-HCH, dieldrin, endosulfan I, and endrin aldehyde on semen quality. For example, elevated dieldrin levels in relation to decreased sperm concentration, sperm count, and sperm motility were only observed among men with CC of CYP2E1 rs2031920 genotypes (all Pinteraction < 0.05). However, these interactions were not statistically significant after the FDR adjustment. Our results suggested that CYP2E1 and GSTT1 polymorphisms may modify the effects of OCP exposures on semen quality. Due to the relatively small size samples, further investigation is warranted to confirm the findings.

Bioaccumulation of organochlorine pesticides in the parasite Cosmocerca sp. (Nematoda: Cosmocercidae) and the amphibian host Amietophrynus regularis (Reuss, 1833) within Lagos metropolis, Nigeria

BackgroundAmphibian species are being threatened worldwide and chemical pollution is one of the leading causes of this decline. The use of agrochemicals such as organochlorine pesticides (OCPs) among the several health and ecological challenges it causes, the sharp amphibian population decline is most pressing.Toad specimens Amietophrynus regularis were sampled from three (3) selected areas; each comprising of natural habitat and dumpsites within Lagos metropolis. MethodsThe congeners of organochlorine pesticides were tested in the liver, intestine, and parasite (Cosmocerca sp.) of the toads and soil samples from the respective locations using gas chromatography-mass spectrometer (GC–MS). Histopathological analyses were conducted on the intestines and liver of the toads using hematoxylin and eosin (H&E) stain and then examined under the binocular dissecting microscope. ResultsThe concentration of aldrin in the intestine of A. regularis sampled at the dumpsites was higher than the concentrations in the intestines of A. regularis in the natural habitat. The concentrations of dieldrin in the uninfected A. regularis at both dumpsite and natural habitat were higher than the concentrations in the infected A. regularis at both environments. This indicated that the parasite Cosmocerca sp. may have played a depurative role in sequestering the concentration of dieldrin in the toads irrespective of the location. The parasites exhibited marked sequestration capacity characterized by the notably high total bioaccumulation rate both in the liver and the intestine at the dumpsite. The stunted villi being the common histological alteration in the infected and uninfected toads at the dumpsite but missing in the uninfected counterparts at the natural habitat may be attributed to the differences in the background concentration of the OCP congeners. ConclusionsThe parasite- Cosmocerca sp. has been shown to be a potential tool in the biomonitoring of these OCP congeners which persists in the environment. Continuous research on these congeners is a searchlight to checkmate the environment to see how compliant industries and the consumers are in terms of regulation of these chemicals.

Status of Dieldrin in vegetable growing soils across a peri-urban agricultural area according to an adapted sampling strategy

Since the fifties, organochlorine pesticides (OCPs) had been used in agriculture to protect vegetables. Two decades after their ban by the Stockholm convention in 2001, OCPs are still present in agricultural soils inducing vegetable contamination with concentrations above Maximum Residue Level (MRL). This is a major concern for a 5 km2 peri-urban vegetable growing valley located in the south west of France. In the present work, the sampling method was developed to clarify the spatial distribution of one OCP, Dieldrin, and its relationship with soil properties at the scale of study area. A total of 99 soil samples was collected for physicochemical analyses and Dieldrin concentrations. Results show Dieldrin concentrations in soils up to 204 μg kg−1. The horizontal distribution of this pesticide is heterogeneous at the study area scale but homogeneous in each reference plot studied. About 85% of the contamination was located in the top soil layers (0–40 cm depth), but Dieldrin may still be quantified at a depth of 80 cm. Among all soil physicochemical parameters analysed, SOM was the most significantly related (P < 10−4) with Dieldrin concentrations, once different grain size fractions were considered. Moreover, results indicate a 33 times higher Dieldrin concentration and/or extractability for coarse sand than for other grain size fractions. These results show that the developed sampling method is adapted for the study area scale as it helps understanding the factors influencing the spatial distribution of Dieldrin. Historical amendments are the predominant factor for the horizontal contamination and deep ploughing for the vertical contamination. Also, the variations of coarse sand repartition in soils prevents identification of relationships between SOM and Dieldrin contamination in bulk soil. Further investigation is required to explain these relationships but these results highlight why no clear relationship between OCPs and SOM was previously identified.

Determination of Median Lethal Concentration (LC50) for Endosulfan, Heptachlor and Dieldrin Pesticides to African Catfish, Clarias gariepinus and Their Impact on Its Behavioral Patterns and Histopathological Responses.

Pesticides such as endosulfan, heptachlor and dieldrin persist in aquatic environments as a result of their resistance to biodegradation. However, there is no adequate information about the toxicity of endosulfan, heptachlor and dieldrin to the aquatic organism, African catfish (Clarias gariepinus)—a high valued widely distributed commercially interesting species. The current experiment was performed with the aim to determine the median lethal concentration (LC50) of endosulfan, heptachlor and dieldrin to African catfish (Clarias gariepinus); their behavioral abnormalities and histopathological alterations in several vital organs. A total of 324 juvenile fish were exposed for 96 h to six concentrations of endosulfan and dieldrin at 0, 0.001, 0.002, 0.004, 0.008 and 0.016 ppm, and to heptachlor at concentrations of 0, 0.02, 0.04, 0.08, 0.16 and 0.32 ppm for dose-response tests. The study demonstrated that the species is highly susceptible to those contaminants showing a number of behavioral abnormalities and histopathological changes in gill, liver and muscle. The 96-h LC50 value of endosulfan, dieldrin and heptachlor for the African catfish was found as 0.004 (0.001−0.01) mg/L, 0.006 mg/L and 0.056 (0.006−0.144) mg/L, respectively. Abnormal behaviors such as erratic jerky swimming, frequent surfacing movement with gulping of air, secretion of mucus on the body and gills were observed in response to the increasing exposure concentrations. Histopathological alterations of liver, gill and muscle tissues were demonstrated as vacuolization in hepatocytes, congestion of red blood cells (RBCs) in hepatic portal vein; deformed secondary lamellae and disintegrated myotomes with disintegrated epidermis, respectively. These findings are important to monitor and responsibly manage pesticide use in and around C. gariepinus aquacultural areas.

Biochar reduced extractable dieldrin concentrations and promoted oligotrophic growth including microbial degraders of chlorinated pollutants

The role of organic amendments for natural degradation of aged persistent organic pollutants (POPs) in agricultural soils remains controversial. We hypothesised that organic amendments enhance bacterial activity and function at the community level, facilitating the degradation of aged POPs. An incubation study was conducted in a closed chamber over 12 months to assess the effects of selected organic amendments on extractable residues of aged dieldrin. The role of bacterial diversity and changes in community function was explored through sequenced marker genes. Linear mixed effect models indicated that, independent of amendment type, cumulative CO2 release was negatively associated with decreases in dieldrin concentration, by up to 7% per µmol CO2–C respired by microorganisms. The addition of poultry litter led to the highest daily carbon mineralisation, which was associated with low dieldrin dissipation after 9 months. In comparison, biochar resulted in significant decreases in extractable dieldrin residues over time, which coincided with shifts towards aerobic, oligotrophic, gram-negative bacteria, some with dehalogenation metabolism, and with increased potentials for biosynthesis of membrane components such as fatty acids and high redox quinones. The results supported an alternative theory that labile carbon promoted blooms of copiotrophic growth, which suppressed the required community-level traits and oligotrophic diversity to degrade chlorinated pollutants.

Monitoring of Organochlorine Pesticide and Polychlorinated Biphenyl Residues in Common Swifts (Apus apus) in the Region of Hannover, Lower Saxony, Germany.

The use of pesticides is associated with the decline of several avian species. In this study, we monitored the organochlorine contaminants in common swifts (Apus apus) in the years 2016 to 2018. These long-distance migrants breed in Europe and winter in Africa. Their only feeding source is aerial plankton. Pooled organ samples of 42 adult and 40 juvenile swifts were tested with the multi-residue method by gas chromatography-mass spectrometry (GC-TOF/MS). Predominantly, 4,4′-DDE, dieldrin, hexachlorobenzene (HCB), lindane and polychlorinated biphenyls (PCBs) were found in most of these common swifts. Only 4,4′-DDE (adult: 83 ± 70 μg/kg, juvenile: 17 ± 39 μg/kg) and dieldrin (adult: 2 ± 3 μg/kg, juvenile: 0.3 ± 1 μg/kg) concentrations were significantly different between adult and juvenile birds. All detected concentrations in our study were far lower than the previously recorded pesticide concentrations of common swifts in Italy and those which are known to cause toxicity and death in birds.

THE CURRENT SITUATION OF HEAVY METALS AND PLANT PROTECTION CHEMICALS IN CHEESE IN HO CHI MINH CITY 2020

Objectives: To determine the level of contamination of heavy metals and plant protection chemicals in cheese in Ho Chi Minh City, 2020. Subjects and methods: Select 60 most popular commercial cheese products in the study area (based on data reported by the City Food Safety Bureau). In which, 30 domestic products and 30 imported products. Evaluate the contamination level of some chemical parameters. Results and Conclusion: Lead concentration was 0.011 ± 0.007 mg / kg, arsenic concentration was 0.237 ± 0.181 mg / kg, cadmium concentration is 0.481 ± 0.371 mg / kg, Mercury concentration is 0.017 ± 0.018 mg / kg for domestic products. Lead concentration was 0.005 ± 0.007 mg / kg, Arsenic concentration was 0.099 ± 0.14 mg / kg, Cadmium concentration was 0.380 ± 0.358 mg / kg, Mercury concentration is 0.019 ± 0.018 mg / kg for the imported product. Lead concentration exceeded the permitted limit in 2/30 domestic product samples and 1/30 imported samples. Arsenic concentration exceeded the permitted limit in 1/30 of the domestic product sample. Cadmium concentration exceeded the permitted limit in 2/30 domestic product samples. Mercury concentration did not exceed the limit on all tested samples. Carbaryl concentration in domestic product samples was 25.52 ± 16.17 μg / kg, in imported product samples was 12.67 ± 14.26 μg / kg; Endosulfan concentration in domestic product samples was 4,301 ± 2,878 μg / kg, in imported products was 3.18 ± 3.40 μg / kg; Aldrin and Dieldrin concentrations in domestic product samples were&#x0D; 3.47 ± 2.07, in imported products was 1.94 ± 2.13 μg / kg. No sample contains plant protection chemical with concentration exceeded allowed limit for both domestic and imported products.

Distribution and ECo-Toxicological Risk Assessment of Legacy Persistent Organic Pollutants in Surface Water of Talar, Babolrood and Haraz Rivers

In the outer Alborz Range in the Northern Province of Iran, the Haraz, Talar and Babolrood Rivers are the three largest rivers where most of the agricultural, aquacultural and industrial activities are found. Total indicator polychlorinated biphenyls (iPCBs) ranged ND–474, ND–273 and ND–559 ng/L in Haraz, Talar and Babolrood Rivers, respectively. Significantly lower (p &lt; 0.05) concentrations of DDT, lindane and dieldrin were observed in the upstream stations than downstream stations of both Babolrood and Haraz Rivers. However, in Talar River, PCB residues in upstream was significantly higher (p &lt; 0.05) than downstream. Furthermore, PCB-28 in Talar River and PCB-101 and PCB-153 in Bablrood and Haraz Rivers were high in water samples at all stations. A significant difference was observed among the stations. In October, November and December, there was negligible variations in total PCB concentration among the stations. Alarming levels of some of the legacy persistent organic pollutants (POPs) may pose adverse effects on the aquatic species dwelling in the Talar, Babolrood and Haraz Rivers of Iran.

Highly decomposed organic carbon mediates the assembly of soil communities with traits for the biodegradation of chlorinated pollutants

To improve biodegradation strategies for chlorinated pollutants, the roles of soil organic matter and microbial function need to be clarified. It was hypothesised that microbial degradation of specific organic fractions in soils enhance community metabolic capability to degrade chlorinated pollutants. This field study used historic records of dieldrin concentrations since 1988 and established relationships between dieldrin dissipation and soil carbon fractions together with bacterial and fungal diversity in surface soils of Kurosol and Chromosol. Sparse partial least squares analysis linked dieldrin dissipation to metabolic activities associated with the highly decomposed carbon fraction. Dieldrin dissipation, after three decades of natural attenuation, was associated with increased bacterial species fitness for the decomposition of recalcitrant carbon substrates including synthetic chlorinated pollutants. These metabolic capabilities were linked to the decomposed carbon fraction, an important driver for the microbial community and function. Common bacterial traits among taxonomic groups enriched in samples with high dieldrin dissipation included their slow growth, large genome and complex metabolism which supported the notion that metabolic strategies for dieldrin degradation evolved in an energy-low soil environment. The findings provide new perspectives for bioremediation strategies and suggest that soil management should aim at stimulating metabolism at the decomposed, fine carbon fraction.

Dissipation of organochlorine insecticide residues in the environment of Taiwan, 1973-1999

Organochlorine insecticides were used in Taiwan for agricultural and public health purposes mainly from 1950 to 1974. In this study, various survey and analysis studies on soil, water, sediment and animals from 1973 to 1999 were compared, temporal trends were analyzed, and the significance was discussed. In 1973, DDT, DDE, DDD, dieldrin, lindane and aldrin were the major organochlorine insecticides found at higher levels in rice paddy soil in Taiwan. In 1981, average total DDTs concentration of surface soil decreased to one-third of the 1973 level. Subsequently in 1994, total DDTs concentration in surface soil again decreased to one-third of the 1981 level. Dieldrin, lindane and aldrin concentrations decreased even faster and were much lower compared to DDT since 1981. Organochlorine insecticide mean concentrations in river water had reached ppt levels from 1973-1976, but were rarely detected in the 1990s. River sediment concentrations showed a rapid decrease from 1973 to 1976, but although there were variations among different rivers in Taiwan, sediment concentrations of lindane, DDT, DDE and aldrin reached a few ppb and were higher in 1981 compared to 1973-1976 on average. In recent years, total organochlorine insecticide concentration decreased to the ppb level, with most individual insecticide concentrations below 1 ppb. Shellfish organochlorine pesticide concentrations were slightly higher than sediment, and shellfish DDT, DDE, aldrin, dieldrin concentrations also showed an increase from 1973 to 1983 on average. The mean concentrations of DDT and aldrin were higher than 10 ppb in shellfish in 1983 and decreased to below the ppb level in the 1990s. Fish muscle contained ppb levels of organochlorine insecticides in 1973. In recent years, most of the organochlorine insecticide concentrations in shellfish and fish were less than 1 ppb except DDE. Duck eggs and human milk had been found to contain sub ppm levels of DDT and DDE in the 1970s and 1980s, but there was few recent data available. Although organochlorine insecticide levels in the environment of Taiwan have fallen fast over the last 26 years, DDTs and other organochlorine insecticide residue levels in higher animals should be determined for their bioaccumulation potential through the food chain.

Levels and distribution pattern of organochlorine pesticide residues in eggs of 22 terrestrial birds from Tamil Nadu, India.

Long-term monitoring is essential to assess the patterns and distribution of the residues of organochlorine pesticides (OCPs) in biota. Bird eggs have several advantages than other environmental matrixes, which have been used extensively to portray the accumulation and distribution of OCPs. The present study investigated the organochlorine pesticide (OCP) residues in eggs of 22 species of terrestrial birds collected from Tamil Nadu, India. Eggs found abandoned were collected during nest monitoring between 2001 and 2008 and analyzed for the presence of organochlorine pesticide residues. The results showed that the mean concentrations of total hexachlorohexane (∑HCHs), total dichlorodiphenyltrichloroethane (∑DDTs), heptachlor epoxide, and dieldrin ranged from non-detectable (nd) to 2800ng/g, nd to1000 ng/g, nd to 700ng/g, and nd to 240ng/g on a wet mass (wm) basis, respectively. The variation in magnitude of contamination among the species and feeding guilds were not significantly different (p > 0.05). Among the OCPs analyzed, the residues of β-HCH and p,p'-DDE were found to be the abundant in concentration. Similarly, among various bird species studied, the highest concentrations of ∑OCPs (> 5000ng/g wm) were recorded in the eggs of gray junglefowl, scaly-breasted munia, and red-whiskered bulbul. This may be due to their widespread occurrence of their habitat at proximity to the agricultural fields, where organochlorines were in use until recently. Among the various contaminants analyzed, concentrations of p,p'-DDE and heptachlor epoxide exceeded the threshold levels of toxicity for wild birds in > 5% of the egg samples. Hence, this study indicates the need for continued monitoring and further systematic ecotoxicological investigation of these compounds not only in eggs but also in other environmental media.

Legacy and current pesticide residues in Syr Darya, Kazakhstan: Contamination status, seasonal variation and preliminary ecological risk assessment

The Syr Darya is one of two major rivers in Central Asia supplying critical fresh water to the Aral Sea. In spite of the river’s importance and agriculturally-intensive history, few studies have provided a modern evaluation of and the occurrence of pesticide residues potential effects to aquatic life. The primary goal of this investigation was to determine seasonal variations in ambient concentrations of modern and legacy pesticides in bottom sediment and water of the Syr Darya in Kazakhstan (KZ) downstream from an agriculturally-intensive watershed in Uzbekistan. Grab samples and passive samplers were used at five remote sampling stations during June 2015 to provide a baseline for ecotoxicological evaluation. Results were compared with samples collected during and after the agricultural growing season. Polar organic chemical integrative samplers (POCIS) were used in June and calibrated for time-weighted average concentrations of current use pesticides. Among legacy chlorinated pesticides measured in grab samples from the river, lindane (γ-HCH) was detected most frequently with the highest concentrations occurring during June. For all the sampling events, residues of lindane (γ-HCH) ranged from 0.014 to 0.24 μg/L detected in water samples, are among the highest concentrations reported for rivers globally. Concentrations of γ-HCH, p,p’-DDE and dieldrin were highest in October when dieldrin concentrations approached 0.4 μg/L. Sources of legacy pesticides may be either illicit upstream use or evidence of previous atmospheric contamination of glacial meltwater. Chronic exposure to these residues may lead to ecological risk to lower order organisms in both the sediment and water column.

Shrimp/prawn farming status in south-west region of Bangladesh in context of quality control and food safety issues

To determine hazardous antibiotics/chemicals and pesticides residues in Good Aquaculture Practice(GAP) and non-GAP farms and exploring the post-harvest management techniques of shrimp/ prawn forensuring its food safety issues, a study was conducted from July 2016 to June 2019 in three upazilas viz.Bagerhat Sadar, Rampal and Kachua of Bagerhat district. A total of 550 shrimp/prawn farms were randomlysurveyed considering GAP criteria. The farms were categorized as Category A- the farms which comply 90-100% GAP criteria; Category B- farms which comply 70-&lt; 90% GAP criteria and Category C- farms whichcomply 50-&lt;70% GAP criteria. From the study it was found that only 1.67±0.58 % farms were underCategory-A, 37.67±6.81 % farms were under Category-B and 53±6.08 % farms were under Category-C. Atotal of 108 shrimp/prawn samples were collected in which 30% samples were from GAP farms and 70%samples were from non-GAP farms. Collected samples were analyzed for hazardous antibiotics/chemicals andpesticides residues (Heptachlor, Endrin, Dieldrin and DDT) using LC-MS and GC-MS machine. Nohazardous Nitrofuran and Chloramphenicol metabolites were found from the collected samples and noresidual concentrations of Heptachlor, Endrin, Dieldrin and DDT were found from GAP samples. In non-GAP samples, 14.8% samples contained some residues of Heptachlor, Endrin and Dieldrin in which 10.2%samples residues were lower than the Maximum Residual Limit (MRL) which is not harmful for humanhealth. Only 4.6% samples had residues which were slightly higher than the MRL. Exploration of postharvestmanagement techniques of shrimp and prawn were done by observing the icing system quality andtransportation system from farms to market/depot. It was found that 5.67±2.08% farmer used proper icingand transportation system as well, 16.33±3.21% farmers used moderate icing and transportation system and78±2% farmers used poor icing and transportation system. It was also observed that pathogenic bacterialload was higher in poor icing and transportation system as well than the proper icing and transportationsystem. From the study it can be concluded that, if farmers follow at least 50% of the GAP criteria then thefoods (shrimp/prawn) will be safer for human consumption.

Organochlorine pesticides and polycyclic aromatic hydrocarbons in marine sediments and polychaete worms from the west coast of Unguja island, Tanzania

The coastal areas of Stone Town, on the island of Unguja that is part of Zanzibar, are subjected to different anthropogenic activities and receive untreated municipal wastes that are likely to carry organic pollutants that can bio-accumulate in marine organisms. Sediments and polychaete worms Capitella capitata collected from coastal sites north and south of Stone Town were analysed for organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs) using GC–MS to assess their pollution status in the coastal environment and uptake by the food web. The analysis revealed quantifiable concentrations of DDTs, cyclodienes, and HCHs, and six of the 11 USEPA-priority PAHs. The concentration ranges of ΣOCPs were 0.1–100 ng/g dm (dry mass) and 8.5–96 ng/g lm (lipid mass) in sediments and worms, respectively. The concentrations of ΣPAHs6 ranged from non-detectable to 27 ng/g dm in sediments and non-detectable to 18 ng/g lm (lipid mass) in worms. Malindi harbour was the most contaminated of all sites with respect to the pollutants we measured in both sediments and worms. The relative compositions of the OCPs suggest legacy use of DDT and technical HCH, and more recent use of lindane. The relatively higher proportion of low molecular mass PAHs to high molecular mass PAHs suggests major contributions from petrogenic sources in the study area. The results demonstrated bioavailability and uptake of OCPs and PAHs to the food web via C. capitata. Concentrations of DDTs, HCHs, and dieldrin exceed sediment quality guidelines, indicating risk to sediment-dwelling organisms, as well as organisms that eat them. It is likely that other toxic compounds are present, suggesting that the current assessment may underestimate the risk. Due to the indicated risk, further work is needed to look at coastal distributions, terrestrial concentrations, and accumulation of pollutants into higher trophic level organisms of Zanzibar and associated seas.

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.

Composition of soil organic matter drives total loss of dieldrin and dichlorodiphenyltrichloroethane in high-value pastures over thirty years.

The residues of dieldrin and dichlorodiphenyltrichloroethane (DDT), internationally-banned agricultural insecticides, continue to exceed government guidelines in some surface soils 30 years after use. Little is known regarding the soil factors and microbial community dynamics associated with the in-situ biodegradation of these organochlorine chemicals. We hypothesised that soil organic matter, a key factor affecting microbial biomass and diversity, affects the biodegradation and total loss of the pollutants 30 years after use. We sampled 12 contaminated paddocks with residue concentrations monitoring data since 1988 that represent two different agricultural surface-soils. The total loss and current concentrations of the residues was correlated with soil physicochemical properties, microbial biomass carbon, microbial community diversity indices and microbial community abundance. Current dieldrin and DDT residue concentrations were positively correlated with soil organic matter and clay contents. However, key indicators for loss of residues after 23-30 years were low carbon-to‑nitrogen ratios, high microbial-C-to-total-C ratios and high fungal community evenness. The results support the composition of soil organic matter as an important factor affecting degradation of organochlorines and that co-metabolism of dieldrin and DDT could be enhanced by manipulating the composition of soil organic matter to cater for a broad diversity of microbial function.

Analysis of trends and variability of toxic concentrations in the Niagara River using the Hilbert-Huang transform method

This study introduces a more recent data analysis method, Hilbert Huang Transform method (HHT), to describe contaminant concentration data of a non-stationary and non-linear nature. In order to improve the modeling of the contaminant concentrations, it is proposed to first process the data using the Empirical mode decomposition (EMD) method from HHT to obtain a collection of intrinsic mode functions (IMFs) which can then be modeled separately using either autoregressive moving average (ARMA) models expanded with a seasonal term, or linear regression analysis, depending on the nature of the IMF. Three priority contaminants measured at Niagara-on-the-Lakes are selected for this study. It is found that the trend of fluoranthene concentrations from April of 1986 to March of 1997 is decreasing and then beginning to increase; the 1,2,4-trichlorobenzene concentrations are decreasing; while the dieldrin concentrations are decreasing. With HHT, appropriate time series models can be identified and constructed for the studied contaminant concentrations to better illustrate the variability of each IMF (and thus the contaminant concentrations) for the studied period. For all data sets modeled in this study, pre-processing the data with HHT allowed for higher R2 values, correlation coefficients and lower sum of squared errors when compared to modeling without HHT. It is thus confirmed that pre-processing the data with HHT and modeling with time series analysis will provide a more effective means of the studied data sets when identifying and analyzing the trends and variability of studied contaminant concentrations in the Niagara River.