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The utilization of pesticides has experienced a substantial rise in order to enhance both the quantity and caliber of the produced goods. Agricultural runoff, a major source of nonpoint pollution, adversely impacts surface water, groundwater, soil and sediment quality in the watershed. Especially, organochlorine pesticides have adverse effects on the environment because of their toxicity, persistence and bioaccumulation. In this study, the presence of organochlorine pesticides (DDTs- dichlorodiphenyltrichloroethane and HCHs- hexachlorocyclohexane) in the environment of the dryland agricultural watershed, was determined. For this purpose, soil, sediment and water samples from the landscape of pond were collected. The concentrations of organochlorine pesticides in water, sediment, and soil ranged from 0.0005 to 0.0138 μg/L, 0.03 to 1.02 μg/kg, and 0.54 to 52 μg/kg, respectively. The persistence of these pesticides in soil and sediment poses long-term risks to both terrestrial and aquatic ecosystems. Sediment, as a significant reservoir for these contaminants, can act as a secondary source of pollution, releasing pesticides back into the water column under certain environmental conditions. Similarly, soil contamination not only affects plant health and productivity but also leads to further leaching and runoff into water bodies. The behavior of a toxic substance in water, soil and sediment environment, which is organochlorine pesticide, in a well-mixed lake watershed, was modeled using mass balances in the lake. Statistical analysis, including a paired t-test and calculation of the Nash-Sutcliffe index, confirms the consistency and reliability of the model’s predictions compared to observed data. Simulated concentrations closely matched observed values, and the distribution patterns and trends remained consistent across different months. Moreover, the Risk Quotient (RQ) for DDTs and HCHs is less than 0.1, indicating low ecological risk. [ABSTRACT FROM AUTHOR]

This paper presents the remediation of polluted soils with chlorinated pesticides (HCH, DDX) by zerovalent iron technology (ZVI). We performed soil remediation tests with iron (two grinding sizes), three doses, with iron and acetic acid (two doses for each dose of iron and for each type of grinding iron size). In the study was applied 99 tests (samples). The diminishing of HCH and DDX concentrations in treated samples is more significant with the increasing of iron and acetic acid doses, for the same contact time: 99% HCH and 91% DDX for large iron particles and 95% HCH and 82% DDX for small iron particles.

The hexachlorocyclohexane isomers (HCH) are long-banned pesticides. Even though their use has been prohibited for decades, their presence in the environment is still reported worldwide. Wetland + is a registered trademark of the remedial treatment technology consisting of an aerobic sedimentary tank, a permeable reactive barrier, a biosorption system, and an aerobic wetland. This proven method combines a reductive treatment known from PRBs with the natural wetland self-cleaning processes. The average efficiency of the system is 96.8% for chlorobenzenes (ClB) and 81.7% for HCH, during the first 12 months of the system operation. The presence of the genes encoding enzymes involved in the degradation of the HCH compounds indicates that the removal of HCH and ClB occurs not only by chemical removal but also through aerobic and anaerobic combining biodegradation. Changes in abundance and the composition of the diatom community were found to be suitable indicators of the water quality and of the impact of the Wetland + operation on the water ecosystem. The system's annual operation exhibited a markedly higher number of diatom species in the closing profiles of the Ostrovský Creek, the Wetland + effluent recipient. HIGHLIGHTS Wetland+ system achieved high removal rates: 96.8% for ClB and 81.7% for HCH over 12 months.; Aerobic wetland module had the highest abundance of HCH-degrading microorganisms.; Diverse microbial community contributed to HCH degradation and pollutant removal.; Diatom community changes served as reliable water quality indicators.;

Populations of the critically endangered white-rumped vulture (WRV) Gyps bengalensis have declined drastically due to the use of diclofenac for veterinary purposes in Indian subcontinent. Thirty-two dead WRVs collected from three states, namely Gujarat, Assam and Tamil Nadu in India between 2011 and 2014 were investigated to understand the role of diclofenac in the death, and the results were published. Furthermore, since organochlorine pesticides have been linked to long-term impact on populations in many species of birds across the globe, available tissues of 21 WRVs were tested also for six organochlorine pesticides (DDT, HCH, endosulfan, heptachlor, dieldrin and dicofol) and chlorpyrifos. All vultures were found to have had one or more detectable levels of pesticides in their tissues except one. Similarly, all the pesticides included in the study were detected in at least one of the vultures analysed. DDT (95.2%) was the most frequently detected pesticide followed by HCH (90.5%), and DDT (73.6%) contributed the most to the total pesticide load. Total pesticide load ranged between below detection limit (BDL) and 8753.4 ng/g. High levels of total pesticide load recorded in gut contents showed recent exposure to these legacy pesticides even long after their ban. However, it is perceived that studied pesticides' exposure to birds and their presence in the environment is in decreasing trend in India. Although, varying levels of pesticides were detected, all of which were below the levels reported to be toxic, and also reported earlier in the same species in India. Recorded levels may not create a problem to vultures unlike diclofenac; nevertheless, as continued exposure to the pesticides studied may lead to sub lethal effects in birds, it is prudent to monitor these pesticides along with new generation pesticides and NSAIDs in the critically endangered white-rumped vulture in India, towards its conservation. [ABSTRACT FROM AUTHOR]

Lindane (a harmful contaminant) was produced in Sabiñánigo (Huesca, Spain) and deposited at the Sardas landfill. This site contains a large mass of pollutants, which have an extremely large contamination potential of the Ebre River. The site has undergone numerous human interventions that have modified the natural conditions. The site exhibits complex hydrogeological patterns and has been monitored systematically for a long period of time, and a large amount of geological, hydrological, and hydrogeological data are available. Here, a 2D finite element groundwater flow model along a vertical profile heading east–west along the thalweg of the former gully is presented. The main goal is modelling groundwater flow through the landfill, the Gállego River alluvial aquifer, and its interactions with the Sabiñánigo reservoir. The numerical model confirms the prevailing conceptual hydrogeological model of the site. The main results include: (1) Groundwater flows into the landfill mainly along perimeter ditches, which do not properly drain the surface and subsurface runoff (13.84 m3/d) and from the underlying marly rock (8.84 m3/d); (2) The total landfill leachate outflow towards the alluvial floodplain underneath the front slurry wall through a shallow marl layer is equal to 17 m3/d; (3) The oscillations of the Sabiñánigo reservoir water level produce a tidal effect that results in periodic changes of the hydraulic gradient between the alluvial gravels and the reservoir; (4) Groundwater flows generally from the alluvial aquifer towards the reservoir in an average E–W direction with an average Darcy velocity equal to 5 cm/d. The flow direction, however, changes to W–E when the reservoir level rises suddenly and; (5) The hydrodynamic parameters of the alluvial silts and reservoir silting sediments are crucial in determining the influence radius of the inversion of groundwater flow direction when the reservoir level rises suddenly. Model results enhance the confidence of the conceptual model, provide the basis for detailed specific models of the landfill and the alluvial aquifer, and highlight the importance of considering the tidal effect of the reservoir level oscillations. They also provide valuable information for managing the landfill and its impact on the surrounding groundwater system. [ABSTRACT FROM AUTHOR]

Being the third polar region of the earth, the Qinghai-Tibet Plateau (QTP) has a significant impact on the whole earth, especially on the Eurasian environment and ecosystem, making it crucial to understand the environmental changes occurring in the area. However, the exploitation and utilization of mineral resources are affecting the ecosphere of QTP, especially in the farming-pastoral ecotone. More research needs to be conducted on the distribution and sources of persistent organic pollutants in this region. To address this research gap, this study investigates the characteristics of organochlorine pesticides (OCPs) in Ganhe industrial parks (GDIP), located in a farming-pastoral ecotone and the surrounding soils. The study analyzed 22 soil samples collected from two intersections. The findings revealed that hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) were the dominant components of the 15 OCPs, accounting for more than 75% of the total OCPs among sampling sites. These compounds had high mean concentrations of up to 2506.3 and 152.7 μg kg−1, respectively. High levels of OCPs were observed in the southeastern and southern regions of GDIP. Agricultural soils were more susceptible to OCP pollution due to frequent agricultural activities compared to grassland. Source apportionment analysis showed that OCPs in the area might primarily comprise lindane (detected in 54.5% of the samples) and dicofol (detected in 86.4% of the samples), implying that these two OCPs could still be in use in this area. Therefore, further investigation into the use and pollution of OCPs in the farming-pastoral ecotone in the northeast of QTP is necessary, and their impact on the ecosystem needs to be evaluated. [ABSTRACT FROM AUTHOR]

The occurrence and distribution of organochlorine pesticides (OCPs) in aquatic systems is a matter of global concern and poses significant toxicological threats to both organisms and human health. Despite the extensive use of OCPs for pest and disease control in southern Africa, relatively few studies have examined the occurrence and toxicological risks of OCP residues in the region. This study investigates the composition, distribution, and potential sources of OCP contamination in sediments from Richards Bay, a rapidly developing industrial port on the northeast coast of South Africa. Surface sediments collected from Richards Bay Harbour and surrounding areas indicate that OCP contamination in the region is widespread. Total concentrations (∑OCP) in surface samples ranged from 135 to 1020 ng g−1, with hexachlorocyclohexanes (∑HCH; 35–230 ng g−1) and dichlorodiphenyltrichloroethanes (∑DDT; 12–350 ng g−1) the dominant contaminant groups detected. Metabolite isomeric compositions indicate that the presence of aldrin and endosulfan likely result from historical agricultural usage, while recent input of γ-HCH, heptachlor, and endrin may be linked to the illegal use of old pesticide stockpiles. Total DDT concentrations were dominated by p,p′-DDT (80 ± 64 ng g−1), which was attributed to its ongoing use in malaria vector control in the region. A 210Pb-dated sediment core revealed that OCP input to the local environment increased dramatically from relatively low concentrations in the mid-1940s (∑OCP, 355 ng g−1) to peak levels (∑OCP, 781 ng g−1) in the 1980s/1990s. An overall decrease in ∑OCP concentration from the mid-2000s is likely related to restrictions on use following the Stockholm Convention in 2004. Despite current restrictions on use, OCP concentrations exceeded sediment quality guidelines in the vast majority of cases, raising concerns for protected estuarine and mangrove habitats in the area, as well as for local fishing and farming communities. [ABSTRACT FROM AUTHOR]

Organochlorine pesticides (OCPs) show differences in their chemical structure, mechanism of toxicity, and target organisms. However, OCPs also have some common characteristics such as high persistence in the environment, bioaccumulation, and toxicity which lead to health issues. Nowadays, the toxicity of OCPs is well known, but we still do not know all the specific molecular mechanisms leading to their toxicity in mammalians. Therefore, this review aims to collect data about the mode of action of various classes of OCPs, highlighting their differences and common behavioural reactions in the human and animal body. To discuss the OCPs molecular pathways and fate in different systems of the body, three organochlorine insecticides were selected (Dichlorodiphenyltrichloroethane, Hexachlorocyclohexane and Chlordecone), regarding to their widespread use, with consequent effects on the ecosystem and human health. Their common biological responses at the molecular scale and their different interactions in human and animal bodies were highlighted and presented. [ABSTRACT FROM AUTHOR]

Lindane (a harmful contaminant) was produced in Sabiñánigo (Huesca, Spain) and deposited at the Sardas landfill. This site contains a large mass of pollutants, which have an extremely large contamination potential of the Ebre River. The site has undergone numerous human interventions that have modified the natural conditions. The site exhibits complex hydrogeological patterns and has been monitored systematically for a long period of time, and a large amount of geological, hydrological, and hydrogeological data are available. Here, a 2D finite element groundwater flow model along a vertical profile heading east–west along the thalweg of the former gully is presented. The main goal is modelling groundwater flow through the landfill, the Gállego River alluvial aquifer, and its interactions with the Sabiñánigo reservoir. The numerical model confirms the prevailing conceptual hydrogeological model of the site. The main results include: (1) Groundwater flows into the landfill mainly along perimeter ditches, which do not properly drain the surface and subsurface runoff (13.84 m3/d) and from the underlying marly rock (8.84 m3/d); (2) The total landfill leachate outflow towards the alluvial floodplain underneath the front slurry wall through a shallow marl layer is equal to 17 m3/d; (3) The oscillations of the Sabiñánigo reservoir water level produce a tidal effect that results in periodic changes of the hydraulic gradient between the alluvial gravels and the reservoir; (4) Groundwater flows generally from the alluvial aquifer towards the reservoir in an average E–W direction with an average Darcy velocity equal to 5 cm/d. The flow direction, however, changes to W–E when the reservoir level rises suddenly and; (5) The hydrodynamic parameters of the alluvial silts and reservoir silting sediments are crucial in determining the influence radius of the inversion of groundwater flow direction when the reservoir level rises suddenly. Model results enhance the confidence of the conceptual model, provide the basis for detailed specific models of the landfill and the alluvial aquifer, and highlight the importance of considering the tidal effect of the reservoir level oscillations. They also provide valuable information for managing the landfill and its impact on the surrounding groundwater system.

Hexachlorocyclohexane (HCH) waste isomers from lindane production are the largest single POPs legacy, with an estimated 4.8 to 7.4 million tonnes of disposed waste. The largest part of this waste – 1.8 to 3 million tonnes – was disposed in Europe, where most producers were located. This paper provides a short overview of projects supported by the European Union (EU) to address this waste legacy and to implement the Stockholm Convention for this group of POPs with associated protection of soil, ecosystems and human health. We report here particularly on the results of a project financed by the EU called the “HCH in EU project”, which aimed to develop a systematic inventory of sites where HCH was handled and potentially resulted in contamination. The compiled information provide guidance for competent authorities to further assess their national HCH inventory and to further develop a strategy to address this large POP legacy in future. The systematic inventory revealed that there were at least 299 sites where HCH was handled. These sites include 54 former production sites, 76 pesticide processing plants that used lindane, 59 uncontrolled HCH waste isomer deposits, 29 landfills with HCH waste, 34 former or current storage sites for stocks of obsolete pesticides including technical HCH or lindane, and 16 HCH treatment or disposal sites. Additionally, at 31 of the sites lindane/technical HCH was used in applications with significant risk of soil pollution, such as wood treatment. The number of sites in this latter category is likely higher and will need further assessment. In addition to this inventory, the “HCH in EU project” produced detailed country reports, a guidance document for how to find potentially HCH-impacted sites, and a strategy document for implementing the sustainable management of these sites EU-wide, with proposed actions at the EU, country, and site level. Furthermore, the project has facilitated information exchange and – together with other related EU projects – has led to sharing information and best practices among member states and to establishing a network of authorities and other stakeholders working on the lindane/HCH waste legacy. This collaboration will facilitate a more systematic and better coordinated process to further assess, secure, and remediate the large HCH waste legacy and reduce and control lindane/HCH releases in the EU and possibly beyond. Such a coordinated effort and exchange of information for inventorying and managing contaminated sites might also be useful for other POPs such as PFOS/PFOA or dioxins.

Hexachlorocyclohexanes (HCHs) are persistent organochlorine pesticides with the adverse effects on human health and the environment. The effect of delta-isomer of hexachlorocyclohexane (δ-HCH) on germination, growth parameters and physiological parameters was studied in different Alnus glutinosa (L.) Gaertn. progeny of resistant genotypes to pathogen Phytophthora ×alni. Two experiments were performed: a short-term experiment to determine the effect of δ-HCH on total germination (GT), germination energy (GE), speed of germination (SG), shoot length and biomass of seedlings, and a long-term experiment devoted to remediation aspects. In addition, changes in the hormonal system of alders were monitored in both cases. Significant differences were found between the treated and control group in most of the evaluated characteristics. Also, the content of studied phytohormones differs between groups. Furthermore, the obtained results indicate genetically determined variability in response to δ-HCH. Of the six tested, the Březové and Tuřany progeny seem to be suitable candidates for phytoremediation because of the adaptation to stress conditions or high remediation efficiency. The rest of tested progeny seems to be unsuitable due to higher mortality, lower remediation efficiency and higher levels of stress hormones resulting in significant decrease in biomass and plant height. Moreover, results indicate the role of the plant as a remediation accelerator, probably through released exudates, and a positive effect on the soil microbiome as the presence of plants increased the remediation efficiency by 20.85 – 35.89%. The obtained research findings may be helpful in better understanding the processes involved in removing these pesticides from the soil. Further research should be focused on rhizosphere microbiome, mechanism of in-plant isomerization and metabolites identification.

Persistent organic pollutants cause a myriad of ecosystem perturbances with long lasting consequences for their resident animal, plant and microbial communities. Structural shifts in biodiversity and changes in population dynamics are inextricably tied to the introduction of anthropogenic pollutants. Sequentially, contaminated ecosystems represent an interesting field of inquiry as to the lines of succession following the introduction and continued existence of such toxic compounds. Soil microbial communities in particular have been described as the first responders to both trace and abundant amounts of pollutants. Hexachlorocyclohexane (HCH) is one such persistent organochloric pollutant, historically used as a wide spectrum insecticide and acaricide in agriculture and medicine. HCH’s long soil half-life has ensured it remains a continuous pernicious problem for areas where extensive HCH manufacture and utilization have occurred. The Skopje valley is one such area, where within the boundaries of the factory OHIS, approximately 30 million kilograms of technical grade HCH waste has been disposed of in two landfills. These landfills act as active loci of HCH contamination, allowing slow and steady infiltration onto surrounding areas, including fertile farm fields, human communities and a small riparian biotope. In order to study the microbial inhabitants of HCH contaminated soils, samples were acquired from surrounding areas and within the official boundaries of OHIS. These samples served as initial matrices for the isolation of filamentous fungal strains with the end goal of surveying the various distinct qualitative morphological adaptations present among these communities. Among the 35 morphologically unique strains, the majority showed hirsute morphology (74%), septate hyphae (71%) and belonged to the phylum Ascomycota (88%). The findings of this study suggest that similar physiognomic strains occupy similar functions in contaminated ecosystems. Studying these microbial inhabitants and their various adaptations may yield novel insights into potential bioremediation avenues for managing HCH and other organochloric contaminants. Thus the goal of the presented study is to evaluate the fungal microbial communities present in the HCH contaminated soils near OHIS, North Macedonia. By determining certain trends of occurrences, these communities may then further serve as pools for the selection and development of novel bioremediation agents for the betterment of contaminated areas across the whole of North Macedonia.These isolates could contribute for the improvement of the wider market for soil remediation products and could also be utilized to create a clean enviorment for all of us. Isolates can participate in the production of new Macedonian product used for bioremediation processes. [ABSTRACT FROM AUTHOR]

Compared to aquatic ecosystems, limited information exists on organochlorine accumulation in terrestrial ecosystems, and this is specifically true for terrestrial carnivores that have received limited attention in terms of studies on pollutant bioaccumulation. The African Leopard, Panthera pardus pardus (Linnaeus, 1758), is a popular focal species for research by ethologists and ecologists, but a noticeable knowledge gap exists with regards to toxicological aspects. To address this gap, the aim of this study was to determine baseline organochlorine pesticide (OCP) concentrations in blood of live wild and captive leopards in South Africa, and to explore the relationship between OCP levels and different conservation management strategies. Peripheral blood samples of seven captive and seven wild leopards, representing regular and melanistic individuals within the captive population, were collected while under sedation. The ΣOCP concentrations in blood serum were detected by means of GC-ECD. Statistical relationships among pesticide content in leopards from three geographical areas, different sexes, age groups and conservation status were examined. Captive leopards from this study had a slightly higher mean ΣOCP concentration (901 pg/ml) than wild leopards (768 pg/ml), and captive females had lower mean levels of ΣOCPs (797 pg/ml) than males (1,058 pg/ml). OCPs accumulated in the following order DDTs (27%) > HCHs (21%) > Heptachlors (15%) > CHLs (15%) > Drins (14%) > HCB (8%). Differences in OCP composition profiles of resampled captive individuals were also found. The sources of OCPs in the leopards can be attributed to the historic and current use of, e.g., DDT and HCHs, for malaria vector control and in insecticides/avicides in South Africa. For the captive leopards in this study the main source is possibly contaminated chicken that formed the major portion of their diet. This is the first report on OCP concentrations from leopards in Africa and highlights the need for this parameter to be considered in terms of the conservation management of healthy populations.

The organic pollutants disposed at the Sardas landfill in Sabiñánigo (Huesca, northeastern Spain) by the INQUINOSA lindane factory have reached the Gállego alluvial aquifer and could affect the Sabiñánigo reservoir. The daily oscillations of the reservoir water level produce a tidal effect on the piezometric heads of the aquifer. These oscillations are transmitted in a damped way with a time lag, thus attesting that the silting sediments of the reservoir and the natural silts of the Gállego alluvial are interposed between the reservoir water and the layer of sands and gravels. A 2D finite element groundwater flow and total dissolved hexachlorocyclohexane (HCH) transport model through the Gállego alluvial aquifer is presented here. The flow model was constructed to: (1) Quantify the tidal effect, produced by the daily fluctuations of the reservoir water level on the aquifer; (2) Estimate the hydrodynamic parameters of the layer of sands and gravels; and 3) Estimate the vertical hydraulic conductivity of the silting sediments and silts; and (4) Quantify aquifer/reservoir interactions. The flow model reproduces the dynamics of the tidal effect and attests that groundwater velocity and flow direction changes daily in response to the oscillations of the reservoir level. Model results reproduce the measured well hydrographs and the Darcy velocity derived from tracer tests and confirm the validity of the conceptual model. The transport model of total dissolved HCH simulates the time evolution of the contaminant plume. The computed concentrations of total dissolved HCH and the contaminant mass outflux are very sensitive to changes in the source terms and the distribution coefficient, K d of HCH. The best fit to the measured HCH plumes in September 2010 and December 2020 is obtained with a K d ranging from 1 to 3 L/kg. The computed flux of dissolved HCH leaving the Sardas site in 2020 towards the Sabiñánigo reservoir ranges from 0.6 kg/year for K d = 3 L/kg to 3.1 kg/year for K d = 1 L/kg. The findings of this study will be most useful for planning and designing remedial and containment actions at the Sardas site and other similar lindane-affected sites. [Display omitted] • Oscillations of the reservoir level produce a tidal effect in the aquifer. • Groundwater flow changes from E -W to W-E direction when reservoir level is high. • Polluted groundwater does not discharge directly into the reservoir. • Computed concentrations of dissolved HCH are very sensitive to the K d. • The best fit to measured HCH data is achieved with K d [1, 3] L/kg. [ABSTRACT FROM AUTHOR]

El Diclorodifeniltricloroetano (DDT) y Hexaclorociclohexano (HCH) son disruptores endócrinos cuya presencia en la leche representa un riesgo para la salud. Existe evidencia de que la pasteurización disminuye o incrementa la concentración de plaguicidas organoclorados en productos lácteos. La presente investigación evaluó el efecto de la pasteurización a 63 °C 30 min-1 y 73 °C 15 seg-1 en las concentraciones de DDT, HCH y sus metabolitos en leche bovina, para estimar la exposición dietaria por consumo humano de leche pasteurizada. Se realizó un diseño experimental de bloques al azar con dos tratamientosen 100 muestras de leche recolectadas en Soledad de Doblado y Jamapa, Veracruz, México. Los plaguicidas se cuantificaron por cromatografíade gases con detector de microcaptura de electrones. Los datos se analizaron mediante Análisis de Varianza unifactorial (P

Organochlorine compounds (OCs) are persistent organic pollutants linked to damaging the immune and endocrine systems, leading to a greater susceptibility to infectious diseases at high concentrations. Sepetiba Bay, in the Southeastern Brazilian coast, historically presents anthropogenic activities and environmental contamination that could negatively impact resident populations. In this context, this study aimed to investigate the temporal trends in the accumulation of organochlorine compounds over a 12-year database in the Guiana dolphins' (Sotalia guianensis) resident population from Sepetiba Bay, including individuals collected before, during, and after an unusual mortality event triggered by morbillivirus (n = 85). The influence of biological parameters was also evaluated. The OCs concentrations in the blubber ranged from 0.98 to 739 μg/g of ΣPCB; 0.08–130 μg/g of ΣDDT; <0.002–4.56 μg/g of mirex; <0.002–1.84 μg/g of ΣHCH and <0.001–0.16 μg/g of HCB in lipid weight. Increased temporal trends were found for OCs in Guiana dolphins coinciding with periods of large events of dredging in the region. In this way, our findings suggest that the constant high OCs concentrations throughout the years in this Guiana dolphin population are a result of the constant environmental disturbance in the area, such as dredging. These elevated OCs levels, e.g., ΣPCB concentrations found above the known thresholds, may impair the response of the immune system during outbreak periods, which could lead the population to a progressive decline. [Display omitted] • Temporal trends of organochlorine compounds (OCs) over a 12-year in Guiana dolphin. • Sampling period included an unusual mortality event (UME) in Sepetiba Bay. • Variations in OCs level patterns coincided with large dredging events in the area. • Most ΣPCB levels exceeded the estimated thresholds for immunosuppressive effects. • High OCs concentrations due to dredging may impair the immunity during outbreaks. [ABSTRACT FROM AUTHOR]

Background. Fluted pumpkin (Telfairia occidentalis) and amaranth (Amaranthus spp.) are common leafy vegetables produced and consumed in southwestern Nigeria. These vegetables attract insect pests which are controlled by pesticides that may have adverse impacts on human health. Objectives. To determine the levels of dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) pesticide residues in the two vegetables and evaluate the potential health risks associated with their consumption. Methods. The pesticide residue levels were quantitatively and qualitatively determined using a gas chromatograph coupled with electron capture detector. Health risk assessment were performed using estimated average daily intake and hazard indices for two weight categories: children (16.7 kg) and adults (60 kg). Results. The results showed that delta-HCH, DDT and methoxychlor were predominantly detected in the two vegetables from both farms and markets. In amaranth, the mean concentration of methoxychlor, DDT and delta-HCH were 4.590 ± 2.774 mg/kg (dry weight (dw)), 0.757 ± 0.457 mg/kg (dw) and 0.577 ± 0.390 mg/kg (dw), respectively, while fluted pumpkin levels were 6.223 ± 2.489 mg/kg dw (methoxychlor), 0.504 ± 0.056 mg/kg dw (delta-HCH) and 0.486 ± 0.123 mg/kg dw (DDT). The levels of HCH and DDT residues were generally above the United Kingdom/European Commission maximum residue limit. The analysis of health risk estimates for non-carcinogenic risk revealed that for both vegetables, the hazard quotient for p, p′ DDT and methoxychlor was >1 for both children and adults. The health risk estimates for carcinogenic risk revealed that hazard indices values were >1 for children for both vegetables and alpha-HCH had a hazard index >1 for adults for amaranth. This means the residue exceeds acceptable standard and present potential risk to consumers of these vegetables. Conclusions. The results obtained from the present study indicate that consumption of amaranth contaminated with alpha-HCH could pose a carcinogenic risk for adult consumers. The consumption of the two vegetables could pose both non-carcinogenic and carcinogenic health risks to children and adults. Therefore, there is need for strict enforcement of regulations on pesticide usage to minimize human health risks. Competing Interests. The authors declare no competing financial interests.

El diclorodifeniltricloroetano (DDT) y hexaclorociclohexano (HCH) son disruptores endocrinos cuya presencia en la leche representa un riesgo para la salud. Existe evidencia de que la pasteurización disminuye o incrementa la concentración de plaguicidas organoclorados en productos lácteos. La presente investigación evaluó el efecto de la pasteurización a 63 °C 30 min-1 y 73 °C 15 seg-1 en las concentraciones de DDT, HCH y sus metabolitos en leche bovina, para estimar la exposición dietaria por consumo humano de leche pasteurizada. Se realizó un diseño experimental completamente al azar con dos tratamientos en 100 muestras de leche recolectadas en Soledad de Doblado y Jamapa, Veracruz, México. Los plaguicidas se cuantificaron por cromatografi'a de gases con detector de microcaptura de electrones. Los datos se analizaron mediante análisis de varianza unifactorial (P<0.05) y las medias se compararon con Tukey (P<0.05). La exposición dietaria a plaguicidas se evaluó por la ingesta diaria estimada (IDE) y dosis diaria promedio (DDP) en tres grupos de población. La pasteurización a 73 °C disminuyó 30.94, 44.51, 3.18, 81.23 y 42.82 % las concentraciones de p,p'-DDE, p,p'-DDD, o,p'-DDT, p,p'-DDT y DDT total, respectivamente, así como las concentraciones de ß-HCH, γ-HCH y HCH total (85.68, 18.88 y 99.31 %, respectivamente). La IDE para niños, adultos y ancianos de DDT total fue menor por consumo de leche pasteurizada a 73 °C y de γ-HCH a 63 °C. La DDP de DDT total disminuyó con la pasteurización a 73 °C. La exposición dietaria de DDT y HCH fue mayor en niños. [ABSTRACT FROM AUTHOR]

The paper presents experimental and numerical simulation of the bioremediation in nitrate-, -sulfate-ions and uranium polluted aquifers near the Novosibirsk Chemical Concentrates Plant (NCPP) sludge storage facility. We used two HCh 4.4 (MSU) and PHREEQC 2.18 (USGS) software packages for geochemical modeling and found that the microbial consumption of oxidizers (oxygen and nitrate ions) led to a decrease in the redox potential to –400 mV. The latter plays a key role in the reduction of uranyl ions and stabilization (immobilization) of uranium in low soluble biogenic sediments containing calcium phosphates, sulfides of iron and associated heavy metals. Results of experimental and numerical simulation turned out to be consistent with the composition of mineral phase collected in situ in a discharge area of polluted aquifer. [ABSTRACT FROM AUTHOR]

Abstract The HighPGibbs program is designed to calculate thermodynamic equilibrium of fluid‐rock systems up to depths of lithospheric mantle. It uses the Gibbs free energy minimization function of the HCh package to calculate mineral‐fluid equilibrium. Chemical potentials of minerals are calculated using the equations of states included in HCh; free energy of aqueous species is calculated using the Deep Earth Water model; and activity coefficients of charged species are estimated using the Davies variant of the Debye‐Hückel equation. HighPGibbs was applied to calculate nitrogen speciation in eclogite‐buffered fluids from 400 to 790 °C and 30 to 54 kbar, to evaluate the mobility of nitrogen in subducting oceanic crust. Regardless of whether the protolith was altered (and oxidized) or not, N2(aq) or NH3(aq) is the predominant form of nitrogen in the slab fluids at subarc temperatures, especially in cases of moderate or hot geotherms. Given that molecular nitrogen is highly incompatible in silicate minerals, the simulation indicates that nitrogen (as NH4+) in silicate minerals can be liberated during metamorphic devolatilization. The majority of nitrogen in subducting crusts can be unlocked during slab devolatilization and eventually expelled to the atmosphere via degassing of arc magmas. Therefore, oceanic crusts recycled to deep Earth will be depleted in nitrogen compared to the newly formed crust at spreading centers. As a result of the long‐term mantle convection, large proportions of the bulk silicate Earth may have suffered nitrogen extraction via subduction, and this may account for the nitrogen enrichment in the Earth's atmosphere.

Once deposited onto Arctic ecosystems, persistent organic pollutants (POPs) biomagnify in foodwebs such that relatively high levels have been detected in predators like beluga whales (Delphinapterus leucas). Our study aimed at assessing temporal trends of legacy POPs in eastern Beaufort Sea beluga blubber collected during traditional harvests in the Mackenzie Estuary area, Northwest Territories. Concentrations of polychlorinated biphenyls (PCBs) and 14 pesticides were quantified in 185 blubber samples collected between 1989 and 2015. The majority of legacy POPs analyzed showed no significant changes during the study period (ΣPCBs, Σchlordanes, Σdichlorodiphenyltrichloroethane, hexachlorobenzene, dieldrin, and mirex) and, therefore, did not reflect regulations put into place over the past decades. Although α- (82.6 ± 12.6 and 15.9 ± 1.9 ng/g in 1989 and 2015, respectively) and γ-hexachlorocyclohexane (γ-HCH) (126.6 ± 23.9 and 13.9 ± 0.9 ng/g, respectively) showed significant decrease between 1989 and 2015, β-HCH showed a more complex trend with concentrations increasing between 1989 (71.2 ± 13.4 ng/g) and 2004 (276.8 ± 13.5 ng/g) before decreasing until 2015 (174.7 ± 8.3 ng/g). Differences in trends likely reflect physico-chemical properties affecting transport to the Arctic. With climate change and melting sea ice potentially affecting the transport and release of legacy POPs, continuous monitoring is necessary.

In 1996, a diagnostic study performed in a 16-ha field located in Buenos Aires Province (Argentina), where a chemical industry produced 1,2,3,4,5,6-hexachlorocyclohexane (HCH) from 1960 to 1978, showed contamination with HCH ranging from 10 to 20,000 mg kg−1 dry soil (706.4 mg kg−1 average). For remediation purposes, a forestation plan was put into practice in 1997 employing approximately 12,300 Eucalyptus dunnii seedlings which by 2016 where fully grown into trees that formed a forest where local fauna can be found. Midterm analysis done in 2005, when E. dunnii trees had developed into 8–10 m high trees, indicated that HCH was incorporated into leaves and logs and soil phytoremediation was progressing. Final quantitation analysis of HCH in soil performed in 2016 demonstrated that the 97.2% of the field area was effectively decontaminated with 98.1% overall average efficiency. Thus, this work is the first global example of a successful employment of E. dunnii trees for HCH phytoremediation purposes at field scale. These results may encourage other researchers to test the ability of E. dunnii to phytoremediate soils contaminated with other chlorinated compounds like polychlorinated biphenyls (PCBs), polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). [ABSTRACT FROM AUTHOR]

The HighPGibbs program is designed to calculate thermodynamic equilibrium of fluid‐rock systems up to depths of lithospheric mantle. It uses the Gibbs free energy minimization function of the HCh package to calculate mineral‐fluid equilibrium. Chemical potentials of minerals are calculated using the equations of states included in HCh; free energy of aqueous species is calculated using the Deep Earth Water model; and activity coefficients of charged species are estimated using the Davies variant of the Debye‐Hückel equation. HighPGibbs was applied to calculate nitrogen speciation in eclogite‐buffered fluids from 400 to 790 °C and 30 to 54 kbar, to evaluate the mobility of nitrogen in subducting oceanic crust. Regardless of whether the protolith was altered (and oxidized) or not, N2(aq) or NH3(aq) is the predominant form of nitrogen in the slab fluids at subarc temperatures, especially in cases of moderate or hot geotherms. Given that molecular nitrogen is highly incompatible in silicate minerals, the simulation indicates that nitrogen (as NH4+) in silicate minerals can be liberated during metamorphic devolatilization. The majority of nitrogen in subducting crusts can be unlocked during slab devolatilization and eventually expelled to the atmosphere via degassing of arc magmas. Therefore, oceanic crusts recycled to deep Earth will be depleted in nitrogen compared to the newly formed crust at spreading centers. As a result of the long‐term mantle convection, large proportions of the bulk silicate Earth may have suffered nitrogen extraction via subduction, and this may account for the nitrogen enrichment in the Earth's atmosphere. Plain Language Summary: Thermodynamic simulation is a powerful tool for investigating the geochemistry of fluid‐rock systems. Such simulations are difficult to perform when pressures are higher than 5 kbar. We present a practical tool, HighPGibbs, that can calculate chemical equilibrium at pressures up to ~55 kbar and can be used to predict the behavior of mantle fluids. It was applied to calculate the speciation of nitrogen in subduction zone fluids. The simulations show that molecular nitrogen, which is incompatible in crustal rocks, predominates in most subduction zone fluids. Therefore, most nitrogen in the subducting crusts can be unlocked by the fluids and eventually released to the atmosphere via degassing of arc magmas. Key Points: We present a thermodynamic tool that can simulate fluid‐rock interaction at mantle depthsMost nitrogen in subducting slabs can be liberated via slab devolatilization and eventually expelled to the atmosphere [ABSTRACT FROM AUTHOR]

Pesticide helps to enhance agricultural production, however, it significantly affect both socio and environmental entities of a country. In Nigeria, pesticide is widely used, thus its traces have been detected in water, soil and air. Several studies have already indicated that most of the environmental ecology (air, water, and soil) in Nigeria has been contaminated by persistent organic pesticides like organochlorine and organophosphate. Other reasons of high pesticide residues present in Nigeria environment is due to inappropriate dosage applied of pesticides that leaves behind excess. However, its residues are found above safety levels in the air, water, and soil across the nation. Based on previous analysis, it is indicated that 125,000-130,000 metric ton pesticides are being applied annually in Nigeria. Despite banned of some pesticides such as dichlorodiphenyltrichloroethane- and -Hexachlorocyclohexane, they are still being used by farmers in their agricultural production. Many of the Class 1 (high extremely toxic) pesticides are still being used in developing countries like Nigeria. Hence, there is need to sensitize and educate the general public especially the end-users (farmers) particularly on management practices of pesticides. Considering these entire hazardous situations, in this article the history of pesticide used in Nigeria has been reviewed in detail. The article also discussed the effects of pesticide use in Nigerian waters, soil and on crops. The risk of residual pesticide on agricultural workers, pesticide residue risk preventive measures by the Federal Government of Nigeria, banned and restricted pesticides in Nigeria, Nigerian Government and its efforts to eliminate persistent organic pesticides in use are also reviewed in details.

New method for determination of organochlorine pesticides (DDT and its metabolites, HCH and its isomers) is presented. The method includes a liquid-liquid extraction of pesticides under ultrasound and the substance analysis by gas-liquid chromatography. The degree of DDT and γ-HCH extracting from tissues of marine organisms is (78 ± 2) % and (91 ± 2) %, respectively. The total content of organochlorine pesticides in muscles of walleye pollock from the Okhotsk Sea is evaluated by this method in the range from 25 to 73 pg/g of lipids.

This review provides information on major organochlorine pesticides (OCPs), which were applied in agriculture worldwide in the 1940s–1960s and are still in use in some developing countries (such as India and China). Patterns of their distribution in the environment, toxicity, metabolism, and degradation are described. Their distribution over the components of ecosystems in different regions of the World Ocean, including the Far Eastern seas of Russia (the Sea of Japan, the Sea of Okhotsk, and the Bering Sea), is characterized over the period of 2000–2016. In the Sea of Okhotsk and the Bering Sea, the OCP content of marine organisms is lower than that in other regions of the World Ocean, in particular, in the Sea of Japan. Results show that a pesticide "background" has formed on the planet. The OCP concentrations in the Sea of Okhotsk and the Bering Sea can be considered a background level, while the Sea of Japan is exposed to contamination from countries using these substances in agriculture. [ABSTRACT FROM AUTHOR]

The study of the soil microbial community represents an important step in better understanding the environmental context. Therefore, biological characterisation and physicochemical integration are keys when defining contaminated sites. Fungi play a fundamental role in the soil, by providing and supporting ecological services for ecosystems and human wellbeing. In this research, 52 soil fungal taxa were isolated from in situ pilot reactors installed to a contaminated site in Czech Republic with a high concentration of hexachlorocyclohexane (HCH). Among the identified isolates, 12 strains were selected to evaluate their tolerance to different isomers of HCH by using specific indices (Rt:Rc; T.I.) and to test their potential in xenobiotic biotransformation. Most of the selected taxa was not significantly affected by exposure to HCH, underlining the elevated tolerance of all the tested fungal taxa, and different metabolic intermediates of HCH dechlorination were observed. The oxidative stress responses to HCH for two selected species, Penicillium simplicissimum and Trichoderma harzianum, were investigated in order to explore their toxic responses and to evaluate their potential functioning in bioremediation of contaminated environments. This research suggests that the isolated fungal species may provide opportunities for new eco-friendly, integrated and cost-effective solutions for environmental management and remediation, considering their efficient adaptation to stressful conditions. [ABSTRACT FROM AUTHOR]

Abstract The landfilling and dumping of persistent organic pollutants (POPs) and other persistent hazardous chemicals, such as hexachlorocyclohexane (HCH) isomers can have significantly adverse environmental consequences and cause contamination in soil, water, and atmosphere systems. Approximately 115,000 t of HCH wastes were generated by INQUINOSA Factory located in Sabiñánigo (Aragón, Spain) from 1975 to 1992, and were mainly dumped at Bailín and Sardas landfills. Under the frame of the project plan approved by the Government of Aragón, remediation and containment measures were implemented at the derelict production facility and landfill sites. To protect and assess the local environment, the concentrations of HCH isomers, pentachlorobenzene (PeCB) and hexachlorobenzene (HCB) in air were periodically monitored in the Sardas landfills and surroundings by passive sampling devices. The influence of meteorological parameters was evaluated, showing positive correlations between temperature and HCH and HCB concentrations. The highest HCH levels were detected in Sardas landfill and INQUINOSA Factory sites. PeCB values were statistically higher in Sardas landfill than in Sabiñánigo urban core, nevertheless, HCB concentrations were similar in both sampling points. Statistically positive correlations were found among HCH isomers in all sampling points, showing a major common source. The chlorobenzenes also correlated positively with each other. The α-/γ-HCH ratios were calculated (1.46 ± 1.25; mean ± S.D.), corroborating that concentrations detected were mainly originated from the historical production, storage and waste disposal of technical HCH. Graphical abstract Unlabelled Image Highlights • High levels of HCHs and PeCB were detected at former HCH production and disposal site. • The highest HCH levels were detected in Sardas landfill and INQUINOSA Factory sites. • HCH levels correlated positively with temperature in all sampling points. • Higher PeCB values were detected in Sardas landfill than in Sabiñánigo urban core. • HCB concentrations were comparable to background levels from other locations. [ABSTRACT FROM AUTHOR]

During the last 70 years 1, 2, 3, 4, 5, 6-Hexachlorocyclohexane (HCH) has been one of the most extensively used pesticides. Only the gamma-isomer has insecticidal properties. For the marketing of gamma-HCH (lindane) the other 85% HCH isomers which are formed as by-products during HCH production had to be separated and became finally hazardous waste. For each tonne of lindane 8–12 tonnes of waste HCH isomers were produced and production of the approximately 600,000 t of lindane has therefore generated 4.8 to 7.2 million tonnes of HCH/POPs waste. These waste isomers were mostly buried in uncontrolled dumps at many sites around the world. The stockpiles and the large contaminated sites can be categorized as "mega-sites". Countries with HCH legacy problems include Albania, Argentina, Austria, Azerbaijan, Brazil, China, Croatia, Czech Republic, France, Germany, Hungary, India, Italy, Japan, Macedonia, Nigeria, Poland, Romania, Russia, Slovakia, South Africa, Spain, Switzerland, Turkey, The Netherlands, UK, Ukraine and the USA. As lindane and alpha- and beta-HCH have been listed as POPs in the Stockholm Convention since August 2010, the problem of stockpiles of HCH waste is now documented and globally acknowledged. This article describes briefly the legacy of HCH and lindane that has been created. Three of the mega-sites are being discussed and demonstrate the increase in pollution footprint over time. Recent developments in the EU (including the Sabinanigo project in Aragon/Spain) and on a global level are presented. A short overview is given on lack of activities and on actions of countries within their obligations as Parties of the Stockholm Convention. Furthermore, current country activities supported by the Global Environment Facility (GEF), the "financing mechanism" of the convention, are listed. Finally, conclusions and recommendations are formulated that will contribute to the solution of this problem over the next 25 years. Image 1 • The HCH wastes isomers from lindane production are the largest global POPs waste. • 4 to 7 million tonnes of HCH wastes are disposed around former production sites. • HCH waste contaminate ground/surface water and air and affected environment/food. • The sites need to be highlighted in the Stockholm Convention implementation plans. • Sites should be assessed/secured and plans for long term remediation developed. The production of lindane has resulted in the largest POPs waste legacy due to waste HCH isomers disposed around production sites. Management of this legacy is urgently needed. [ABSTRACT FROM AUTHOR]

This study presents distribution of organochlorines (OCs) including HCH, DDT and PCBs in urban soils, and their environmental and human health risk. Forty-eight soil samples were extracted using ultrasonication, cleaned with modified silica gel chromatography and analyzed by GC-ECD. The observed concentrations of ∑HCH, ∑DDT and ∑PCBs in soils ranged between < 0.01-2.54, 1.30-27.41 and < 0.01-62.8 µg kg−1, respectively, which were lower than the recommended soil quality guidelines. Human health risk was estimated following recommended guidelines. Lifetime average daily dose (LADD), non-cancer risk or hazard quotient (HQ) and incremental lifetime cancer risk (ILCR) for humans due to individual and total OCs were estimated and presented. Estimated LADD were lower than acceptable daily intake and reference dose. Human health risk estimates were lower than safe limit of non-cancer risk (HQ < 1.0) and the acceptable distribution range of ILCR (10−6-10−4). Therefore, this study concluded that present levels of OCs (HCH, DDT and PCBs) in studied soils were low, and subsequently posed low health risk to human population in the study area. [ABSTRACT FROM AUTHOR]

The relevance of the research is caused by the need to study and monitor the ecological and geochemical status of a complex mineral salt deposit of Ebeity Lake. The total industrial reserves of sodium sulfate (mirabilite) in the lake water are 36,89 million tons. In addition, this lake is of interest as a deposit of therapeutic mud, as well as the crustaceans Artemia Salina L. and their cysts. The aim of the study is to determine the main features of macro-, micro-component, organic and mineral composition of the lake Ebeity, as well as to determine the hydrogeochemical processes affecting the distribution of organomineral complexes of elements. Research methods. The lake was studied in summer 2015. The lake and porous waters, as well as bottom sediments were analysed using mass spectral methods, as well as the methods of atomic absorption, flame emission, potentiometry, titration, etc. The study of bottom sediments was also carried out using the X-ray powder diffractometry method with mandatory control of the composition of typical solid samples by X-ray fluorescent analysis using synchrotron radiation with registration on a Si (Li) detector. The results of the studies showed that Ebeity Lake refers to the SO4~Cl-Na composition, the pH of the lake during the sampling period was 5,7, the lake was characterised by anoxic condition. The pore waters of bottom sediments do not differ from the lake water in their major composition, but the concentrations of trace elements are 2-8 times higher than the values in the lake. The study of complexation of elements in lake water shown that most of iron, copper, uranium and thorium is bound to a high molecular organic matter that allows presuming the impossibility of formation of such minerals as goethite, chlorite and Cu (met), obtained during thermodynamic calculations. The results obtained at simulation allowed us to construct a sequence of formation of evaporite minerals in the lakeNa2SO4 x 10H2O+Na2Ca(SO4)2 - Na2SO4+Na4Ca(SO4)3 x 2H2O - NaCl+Na4Mg(SO4)2 x 4H2O. A study of the mineral composition of bottom sediments showed the presence in solid phase of quartz as the main phase, impurities of NaCl, small admixtures of potassium feldspars, plagioclase, and calcite. The salt along the lake and at the bottom is represented by thenardite, a small-medium amount of halite and traces of astrakhanite.

Organochlorine pesticides are highly persistent in aquatic ecosystems. Amphibians, specifically anurans, play an intricate part in the aquatic food web, and have very permeable skin which makes them prone to bioaccumulation of persistent pollutants. In this study the bioaccumulation of various legacy organochlorine pesticides (OCPs)—including dichlorodiphenyltrichloroethane (DDT), currently used for malaria vector control (MVC)—was assessed along with a set of biomarker responses in Müller’s clawed frog Xenopus muelleri collected from the lower Phongolo River floodplain in South Africa. Possible relationships between bioaccumulation and biomarkers (of exposure, oxidative stress biomarkers, and cellular energy allocation) alongside their temporal changes were investigated. The OCP concentrations showed a significant increase over time for the duration of the study. The increase correlated negatively with rainfall from the region. DDT levels were well below expected effects levels with p,p-DDE being the main contributing metabolite. The results of this study indicate OCPs actively accumulate at sub-lethal levels in aquatic frogs from the study area, while showing possible relations towards some of the biochemical stress responses measured. Most notable were negative relationships indicated between p,p-DDE and acetylcholinesterase, malondialdehyde, and carbohydrates and protein energy availability. Levels of DDT were not found to be significantly higher than other legacy pesticides in the frog tissue, although evidence of newly introduced DDT in the frog tissue was found. Further investigation about sub-lethal effects of these pesticides on anurans is required to gain better insight into their full impact on animal livelihood. [ABSTRACT FROM AUTHOR]

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) are restricted compounds that are ubiquitously detected in the environment, including indoor matrices such as air and residential dust. We report concentrations of PCBs and selected OCPs in indoor air and dust from homes in Canada (23 homes) and Czech Republic (20 homes). Indoor air concentrations of PCBs and OCPs were ∼10 times higher than that outdoors. PCB concentrations of ∼450 ng/m 3 were similar in both countries, higher in homes built before the restrictions on PCBs, and had congener profiles consistent with PCB mixtures manufactured or used in each country. All OCP air concentrations were higher in the Czech Republic than in the Canadian samples, suggesting greater indoor use of, for example, DDT and HCH. These data emphasize the persistence of these organochlorine compounds indoors and their presence in homes even decades after new usage was prohibited. Indoor levels of these legacy POPs remain at similar concentrations to compounds of current concern, such as brominated flame retardants and perfluorinated alkyl substances, emphasizing that they deserve ongoing attention in view of knowledge of PCB and OCP toxicity. [ABSTRACT FROM AUTHOR]

Aim. To study the specific destruction features of the HCH isomers complex by the artificially created association Biorem (Pseudomonas putida IMV B-7287, Bacillus megaterium IMV B-7287, Stenotrophomonas maltophilia IMV B-7288) and the native soil microbial association Micros, as well as individual strains - components of the association. Methods: microbiological, gas chromatography, statistical. Results. It was found the Biorem association decomposes the HCH isomers complex in liquid medium to 70.9-86.7% of initial level. S. maltophilia IMV B-7288 starts the destruction process the first, the strains P. putida IMV B-7289 and B. megaterium IMV B-7287 are including the destruction process on the 4th-7th day, therefore the active growth and destruction of HCH were prolonged. It was found that, depending on the conditions, one or another straindestructor decomposed of HCH-isomers more intensively. So it is advisable to combine B. megaterium IMV B-7287, P. putida IMV B-7289 and S. maltophilia IMV B-7288 in the same microbial association (Biorem). Conclusions. Artificially created association of microorganisms-destructors Biorem can be applied as a bacterial preparation for remediation of HCH contaminated areas. [ABSTRACT FROM AUTHOR]

Actinobacteria are well-known degraders of toxic materials that have the ability to tolerate and remove organochloride pesticides; thus, they are used for bioremediation. The biodegradation of organochlorines by actinobacteria has been demonstrated in pure and mixed cultures with the concomitant production of metabolic intermediates including γ-pentachlorocyclohexene (γ-PCCH); 1,3,4,6-tetrachloro-1,4-cyclohexadiene (1,4-TCDN); 1,2-dichlorobenzene (1,2-DCB), 1,3- dichlorobenzene (1,3-DCB), or 1,4-dichlorobenzene (1,4-DCB); 1,2,3-trichlorobenzene (1,2,3-TCB), 1,2,4-trichlorobenzene (1,2,4-TCB), or 1,3,5-trichlorobenzene (1,3,5-TCB); 1,3-DCB; and 1,2-DCB. Chromatography coupled to mass spectrometric detection, especially GC-MS, is typically used to determine HCH-isomer metabolites. The important enzymes involved in HCH isomer degradation metabolic pathways include hexachlorocyclohexane dehydrochlorinase (LinA), haloalkane dehalogenase (LinB), and alcohol dehydrogenase (LinC). The metabolic versatility of these enzymes is known. Advances have been made in the identification of actinobacterial haloalkane dehydrogenase, which is encoded by linB. This knowledge will permit future improvements in biodegradation processes using Actinobacteria. The enzymatic and genetic characterizations of the molecular mechanisms involved in these processes have not been fully elucidated, necessitating further studies. New advances in this area suggest promising results. The scope of this paper encompasses the following: (i) the aerobic degradation pathways of hexachlorocyclohexane (HCH) isomers; (ii) the important genes and enzymes involved in the metabolic pathways of HCH isomer degradation; and (iii) the identification and quantification of intermediate metabolites through gas chromatography coupled to mass spectrometry (GC-MS). [ABSTRACT FROM AUTHOR]

Remediation and management of dumpsites is a worldwide problem that must be addressed to protect human health and the environment. Aragon Government long-term objective is the control of air quality related to landfills used to dump organochlorine waste. The present study evaluated the influence of dismantling works performed in Bailín landfill, an hexachlorocyclohexane (1,2,3,4,5,6-hexaclorohexane; HCH) dumpsite located in the city of Sabiñánigo, Spain. A total of 65,000 t of HCH solid waste and 342,000 t of polluted soil were transferred to a new cell with additional isolating measures going beyond the Spanish legal requirements. To evaluate influence of excavation of the old cell, transfer of waste and the state once the works in Bailín area had finished, levels of α-, β-, γ-, δ- and ɛ- HCH isomers were analyzed in 112 air samples obtained from summer 2014 to autumn 2016 by using passive air samplers. Results showed that: i) the existence of the old landfill and/or the works performed during its dismantling were a source of HCH air contamination, ii) old landfill represented an HCH source even after dismantling work was completed, iii) other sources, tentatively associated to Sardas dumpsite and HCH production site (INQUINOSA Factory) were identified in the surroundings, where management should be addressed. Data comparison reflected a heavier contamination caused by the production, storage, and waste disposal than the corresponding to application of lindane and/or technical HCH in Spain. Meteorological dependence (temperature, solar radiation and relative humidity), α-/γ-HCH ratios and isomer profiles of HCH air concentrations were evaluated for temporal trends and geographic distribution. [ABSTRACT FROM AUTHOR]

Intensive use of chlorinated pesticides from the 1960s to the 1990s has resulted in a diffuse contamination of soils and surface waters in the banana-producing areas of the French West Indies. The purpose of this research was, for the first time, to examine the degradation of two of these persistent pollutants – chlordecone (CLD) and beta-hexachlorocyclohexane (β-HCH) in 1 mg L-1 synthetic aqueous solutions by means of photolysis, (photo-) Fenton oxidation and ozonation processes. Fenton oxidation is not efficient for CLD and yields less than 15% reduction of β-HCH concentration in 5 h. Conversely, both molecules can be quantitatively converted under UV-Vis irradiation reaching 100% of degradation in 5 h, while combination with hydrogen peroxide and ferrous iron does not show any significant improvement except in high wavelength range (>280 nm). Ozonation exhibits comparable but lower degradation rates than UV processes. Preliminary identification of degradation products indicated that hydrochlordecone was formed during photo-Fenton oxidation of CLD, while for β-HCH the major product peak exhibited C3H3Cl2 as most abundant fragment. [ABSTRACT FROM AUTHOR]

The main Mongolian water resources are lakes whose volume has significantly reduced in recent years as a consequence of global warming. This article presents research on three different types of nearly disposed Western Mongolian lakes with a wide range of brines’ composition: Shaazgai-Nuur (soda), Davsan-Nuur (chloride) and Tonhil-Nuur (sulfate). The aim of this study was to determine the differences in geochemical evolution associated with evaporation-crystallization processes of representative lakes of various chemical types. The modelling was performed by using PHREEQC and HCh software that allows application of Pitzer’s approach for saline solutions. The modelling was performed for these natural objects for the first time. The model demonstrated that the evaporation-crystallization processes are different for soda and chloride/sulfate brines. Soda type lake maintained unchanged ion composition while chemical composition of chloride and sulfate lakes went through significant alterations according to a sequence of mineral precipitation. The calculated model did not confirm the possibility of long-term transformation from SO4-Mg brines to Cl-Mg due to evaporative concentration only; additional factors including mixing with inflow water also influence sodium and chloride increase. Close agreement between the model and the actual mineralogical data was observed, testifying to the proper software and reliability of our assumptions. [ABSTRACT FROM AUTHOR]

The economy of the Khorezm Province in Uzbekistan relies on the large-scale agricultural production of cotton. To sustain their staple crop, water from the Amu Darya is diverted for irrigation through canal systems constructed during the early to mid-twentieth century when this region was part of the Soviet Union. These diversions severely reduce river flow to the Aral Sea. The Province has >400 small shallow (<3 m deep) lakes that may have originated because of this intensive irrigation. Sediment cores were collected from 12 lakes to elucidate their origin because this knowledge is critical to understanding water use in Khorezm. Core chronological data indicate that the majority of the lakes investigated are less than 150 years old, which supports a recent origin of the lakes. The thickness of lacustrine sediments in the cores analyzed ranged from 20 to 60 cm in all but two of the lakes, indicating a relatively slow sedimentation rate and a relatively short-term history for the lakes. Hydrologic changes in the lakes are evident from loss on ignition and pollen analyses of a subset of the lake cores. The data indicate that the lakes have transitioned from a dry, saline, arid landscape during pre-lake conditions (low organic carbon content) and low pollen concentrations (in the basal sediments) to the current freshwater lakes (high organic content), with abundant freshwater pollen taxa over the last 50-70 years. Sediments at the base of the cores contain pollen taxa dominated by Chenopodiaceae and Tamarix, indicating that the vegetation growing nearby was tolerant to arid saline conditions. The near surface sediments of the cores are dominated by Typha/Sparganium, which indicate freshwater conditions. Increases in pollen of weeds and crop plants indicate an intensification of agricultural activities since the 1950s in the watersheds of the lakes analyzed. Pesticide profiles of DDT (dichlorodiphenyltrichloroethane) and its degradates and γ-HCH (gamma-hexachlorocyclohexane), which were used during the Soviet era, show peak concentrations in the top 10 cm of some of the cores, where estimated ages of the sediments (1950-1990) are associated with peak pesticide use during the Soviet era. These data indicate that the lakes are relatively young (mostly <150 years old) and that without irrigation and canal inputs from the Amu Darya, the lakes would not exist as freshwater lakes. [ABSTRACT FROM AUTHOR]

Sediment cores from four lakes across the Tibetan Plateau were used as natural archives to study the time trends of organochlorine pesticides (OCPs). The total concentrations of dichlorodiphenyltrichloroethane (ΣDDT) and hexachlorocyclohexane isomers (ΣHCH) were in the range of 0.04–1.61 and 0.08–1.88 ng/g based on dry weight (dw), while the input fluxes were in the range of 0.3–236 and 0.7–295 pg/cm2/y in the core sediments, respectively. The input fluxes of ΣDDT and ΣHCH generally peaked in sediment layers corresponding to the 1970s–1990s and peaked in top sediment layers. The ratio of α/γ-HCH decreased in the top layer sediments, implying that the contribution of lindane (pure γ-HCH) has been increasing in recent years. In addition, the ratio of o,p′-DDT/p,p′-DDT increased significantly over the last 15–20 years, suggesting that dicofol (characterized by high ratio of o,p′-DDT/p,p′-DDT about 7.0) has recently become a relatively more important source of DDT compared to technical DDT itself. The time trends of OCPs recorded in lake sediments examined the impact on such remote alpine regions by human activities. [ABSTRACT FROM AUTHOR]

Large amounts of hexachlorocyclohexanes (HCHs) have been historically applied in the Yangtze River Delta (YRD) region, China. Estimating the air-soil exchange of HCHs after > 30 years of restricted use is important for understanding their cycling in the environment. In this study, air and soil samples were concurrently collected in two seasons at agricultural and industrial sites from a megacity in the YRD region. The concentrations of HCH isomers and the enantiomeric fractions of chiral α -HCH were determined. The mean concentrations of ∑ HCHs in soils from an agricultural area (AA) and an eco-industrial park (EIP) were 1.74 ng/g and 0.652 ng/g, respectively, in winter, and 0.723 ng/g and 0.350 ng/g, respectively, in summer. The mean concentrations of ∑ HCHs in the air from the AA and the EIP were 31.2 pg/m 3 and 47.7 pg/m 3 , respectively, in winter, and 45.0 pg/m 3 and 50.0 pg/m 3 , respectively, in summer. The variations in spatial and seasonal distributions might be related to diverse geographical factors, soil properties and meteorological conditions. Source identification demonstrated that HCHs in most samples were residues from past use, which was further evidenced by the enantiomeric signatures of chiral α -HCH. A preferential degradation of (−)- α -HCH was showed in soils and summer air, while a preferential depletion of (+)- α -HCH was displayed in winter air. The values of the fugacity fraction (ff) of HCHs suggest a net volatilization from soils to air, but long-range transport may also partly contribute to the atmospheric HCHs according to the results from enantiomeric analysis. The human health risk assessments indicated an absence of noncarcinogenic risks and very low carcinogenic risks for HCHs in both soils and air to human health. Results from this study provide valuable data for assessing the fate and health risks of HCHs in the YRD region. [ABSTRACT FROM AUTHOR]