Persistent organic pollutants (PCB, DDT, HCH, HCB & BDE) in eels (Anguilla anguilla) in Scotland: current levels and temporal trends

Current status and strategies for controlling hexachlorobutadiene from multiple perspectives of emission, occurrence, and disposal

Hexachlorobutadiene (HCBD), as an emerging persistent organic pollutant, poses a pressing global environmental issue concerning its reduction and control. However, the lack of systematic studies on the sources and occurrence of HCBD hinders the development of effective disposal technologies. This study addresses HCBD prevention and treatment from multiple perspectives, including source emissions, environmental contamination distribution, and control technologies. The dominant source of HCBD emissions varied by country, mainly industrial production processes of trichloroethylene, perchloroethylene, and carbon tetrachloride in China and magnesium production in Europe. Further research on the relevant generation mechanisms is necessary to develop targeted source control strategies. HCBD has been detected in various environmental media and biological organisms worldwide. Compared to sludge and soil, the concentration of HCBD in the atmosphere and water were relatively higher, particularly in China and Nigeria, with the concentration reaching up to 179 μg/m3 and 2629 μg/L, respectively. Attention should be focused on the water treatment processes to reduce HCBD levels in sludge and ensure the safety of drinking water. Additionally, studies of HCBD exposure levels in organisms should also focus on diet to further assess health risks to humans. Currently, available disposal technologies primarily focus on the treatment of contaminated environmental media, including physical thermal desorption, chemical reduction dechlorination and oxidative degradation, and biodegradation, while the development and application of source control methods remain insufficient. However, these technologies may not completely degrade HCBD, potentially causing secondary pollution. Future efforts should prioritize the development of green, efficient, and thoroughly destructive thermal catalytic technologies, with an emphasis on the integration of multiple techniques. This work provides critical insights for the development and implementation of comprehensive control strategies for HCBD regarding its source, occurrence, and pollution disposal.

Bioaccumulation and dietary bioaccessibility of microplastics composition and cocontaminants in Mediterranean mussels

Microplastics (MPLs) are contaminants of emerging concern (CECs) ubiquitous in aquatic environments, which can be bioaccumulated along the food chain. In this study, the accumulation of polyethylene (PE), polystyrene (PS) and polyethylene terephthalate (PET) microplastics (MPLs) of sizes below 63 μm was assessed in Mediterranean mussels (Mytilus galloprovincialis spp). Moreover, the potential of mussels to uptake and bioaccumulate other organic contaminants, such as triclosan (TCS) and per- and polyfluoroalkyl substances (PFASs), was evaluated with and without the presence of MPLs. Then, the modulation of MPLs in the human bioaccessibility of co-contaminants was assessed by in vitro assays that simulated the human digestion process. Exposure experiments were carried out in 15 L marine microcosms. The bioaccumulation and bioaccessibility of PE, PS, PET, and co-contaminants were assessed by means of liquid chromatography -size exclusion chromatography-coupled to high-resolution mass spectrometry (LC(SEC)-HRMS). Our outcomes confirm that MPL bioaccumulation in filter-feeding organisms is a function of MPL chemical composition and particle sizes. Finally, despite the lower accumulation and bioaccumulation of PFASs in the presence of MPLs, the bioaccessibility assays revealed that PFASs bioaccessibility was favoured in the presence of MPLs. Since part of the bioaccumulated PFASs are adsorbed onto MPL surfaces by hydrophobic and electrostatic interactions, these interactions easily change with the pH during digestion, and the PFASs bioaccessibility increases.

Risk assessment of hexachlorobutadiene (HCBD) in the Korean diet

Hexachlorobutadiene (HCBD) is a persistent organic pollutant (POP), and a toxin whose primary target organ is the kidney. Consequently, quantifying the amount of HCBD in food is essential for determining whether it poses a health risk. The current study established and validated an analytical method for assessing HCBD in food using gas chromatography/mass spectrometry (GC/MS). Subsequently, we conducted for the first time a risk assessment of HCBD through Korean food consumption. The ranges of HCBD concentration in 595 food samples were as follows: not detectable (nd)-0.947 ng/g for agricultural products, nd-0.920 ng/g for animal products, nd-1.323 ng/g for fishery products and nd-1.081 ng/g for processed food products. The daily intakes of HCBD for the general population were 0.22 ng/kg body weight (b.w.)/day for agricultural products, 0.30 ng/kg b.w./day for animal products, 0.07 ng/kg b.w./day for fishery products and 0.33 ng/kg b.w./day for processed food products. These exposure levels are below the tolerable daily intake (TDI, 2 μg/kg body weight/day) established by the National Institute of Food and Drug Safety Evaluation (NiFDS) in the Republic of Korea. Taking into account the risk index of 0.011%, we can, therefore, conclude that there are no health concerns for the Korean population.

A complete check-up of European eel after eight years of restocking in an upland river: Trends in growth, lipid content, sex ratio and health status

By combining field research and careful laboratory analysis of samples over the course of an eight-year study, we met the challenge of assessing the life history traits and health status of eels restocked in freshwater ecosystems. We found that restocked eels exhibited good growth performance; moreover, the stocks were female-dominated, showed a good Fulton's condition factor (K) and lipid stores and had high survival probability estimated using the best model of Jolly-Seber stock assessment method for open populations. A necropsy revealed the absence of internal lesions. A swim bladder examination revealed the absence of the parasite Anguillicola crassus. Polymerase chain reaction (PCR) analyses revealed an increase of Anguillid herpesvirus-1 (AngHV-1) prevalence throughout the study. Most positive subjects expressed viral loads compatible with a latent infection and correlated positively with K. All restocked eels were contaminated by at least one of the organic pollutant congeners studied, but the pollution loads corresponded to the lowest range of pollutant concentrations reported in the available literature for European eels and did not exceed the maximum residue and contaminant limits in food and feed of several national and international regulations. Pollutant loads were negatively correlated with K, lipid content and eel density for polychlorinated biphenyls PCB 138, 153 and 180 and K for pesticides p.p'-DDE, p.p'-DDD, p.p'-DDT and PBDE47. This study highlights the potential role played by upland aquatic ecosystems in enhancing riverine silver eel production from the perspective of species conservation. To be successful, restocking must be accompanied by improved ecosystem quality and migration routes for eels in inland freshwaters. We also provide some recommendations for future research to improve the management of restocking programmes.

Effect of abiotic factors and environmental concentrations on the bioaccumulation of persistent organic and inorganic compounds to freshwater fish and mussels

Many aquatic ecosystems are under persistent stress due to influxes of anthropogenic chemical pollutants. High concentrations can harm entire ecosystems and be toxic to humans. However, in case of highly hydrophobic compounds, their low water solubility precludes direct measurement in water, and thus alternative monitoring strategies are needed. In the present study, we investigated the extent to which bioaccumulated concentrations of persistent compounds can be predicted by concentrations in environmental compartments (water and sediment). Due to their high biomagnification potential, Hg and PFOS were included in this analysis as well. At 44 field locations in Flanders (Belgium), we monitored the concentrations of 11 priority compounds and their derivatives, included in the Water Framework Directive, in both sediment and water (where feasible) and biota (European perch, European eel and freshwater mussels). Besides, some sediment (i.e. total organic carbon (TOC) and clay content) and water characteristics were measured (i.e. pH, oxygen level, conductivity, nitrate, nitrite and dissolved organic carbon (DOC)). Measurements of HCB, HCBD, cis-heptachlorepoxide, HBCD and PFOS in sediment and ∑PCB in water showed a lower detection frequency than in fish samples. While PCB profiles were comparable between all matrices, for PBDE clear differences were detected between sediment and fish profiles, with BDE99 contributing the most for sediment (34%) and BDE47 for fish (≥44%), followed by BDE99 for perch (28%) and BDE100 for eel (25%). Water concentrations for PFOS and benzo(a)pyrene were predictive of respective bioaccumulated concentrations. HCB, ∑PCB and ∑PBDE, concentrations in fish were dependent on sediment concentrations and negatively related to organic compound levels (p < 0.05). Furthermore, pH and nitrite were negatively associated with accumulated concentrations in eel for HCB and PFOS, respectively (p < 0.05). Strong relationships between bioaccumulation and sediment and/or water concentrations strengthened the basis for surrogate monitoring methods. Finally, the extrapolation potential of Hg, ∑PBDE, PFOS, HBCD and ∑PCB between both fish species offered new opportunities in extrapolating different European monitoring frameworks.

Simultaneous determination of tetra-, penta- and hexachlorobutadienes in shellfish by gas chromatography-triple quadrupole mass spectrometry

Polychloro-1,3-butadienes (polyCBDs) are attracting increasing concern due to their high toxicity. However, research on multiple polyCBDs in aquatic biota is still extremely limited. In this study, a sensitive method for simultaneous determination of nine polyCBD (Cl₄-Cl₆) congeners, including six tetrachlorobutadiene (TeCBD) isomers, two pentachlorobutadiene (PeCBD) isomers, and hexachlorobutadiene (HCBD), in shellfish was developed based on accelerated solvent extraction (ASE), solid-phase extraction (SPE) clean-up and gas chromatography-triple quadrupole mass spectrometry (GC-QqQ-MS/MS). Low method limits of detection (MDLs) in the range 0.03-0.21 ng/g dry weight for target analytes with satisfactory recoveries (47.7 %-70.6 %) were achieved. The valid method was then applied to analyze nine polyCBDs congeners in 42 shellfish and 11 fish samples collected from markets in eight coastal cities, China. Trace HCBD was detected in 14 samples, while TeCBDs and PeCBDs were under the MDLs in all the samples, indicating little contamination of these pollutants in the marketed shellfish and fish in China. Multiple polyCBDs especially TeCBDs and PeCBDs were firstly involved in the proposed method and investigation here, which lay the groundwork for future research on the environmental behavior and exposure risks of polyCBDs in aquatic biotas.

Organochlorine Pesticide Ban Facilitated Reproductive Recovery of Chinese Striped Hamsters

Organochlorine pesticides (OCPs) have been used worldwide on an enormous scale over the last century but are banned globally due to environmental persistence and ecotoxicity in recent decades. The long-term effects of OCP ban for agricultural use in China since 1983 on the reproductive health of small terrestrial mammals have never been evaluated in the field. We examined the residue dynamics of OCPs and the reproductive performance of Chinese striped hamsters (Cricetulus barabensis) in North China Plain during 1983-2010 and concluded that the exposure levels of OCPs in hamsters drastically decreased from 2900 ± 740 to 25.2 ± 6.88 ng/g with an average half-life of 5.08 yrs, coinciding with the observed reproductive recovery of hamsters. The population-based reproductive performance of hamsters was significantly and negatively associated with OCP exposure levels after adjusting the contributions from climate and population density factors, indicating that the ban of OCPs has facilitated the reproductive recovery of hamsters by up to 81% contribution. Our findings suggest that the OCP ban is effective to restore reproduction of small terrestrial mammals. Integration of population biology and environmental science is essential to assess the impacts of persistent organic pollutants on ecological safety and biodiversity loss under accelerated global change.

Persistent pollutants exceed toxic thresholds in a freshwater top predator decades after legislative control

Declining emissions of persistent organic pollutants (POPs), subject to international control under the Stockholm convention, are not consistently reflected in biotic samples. To assess spatial and temporal variation in organochlorine pesticides and PCBs in UK freshwaters, we analysed tissues of a sentinel predator, the Eurasian otter, Lutra lutra between 1992 and 2009. Past declines in otter populations have been linked to POPs and it is unclear whether otter recovery is hampered in any areas by their persistence. PCBs, DDT (and derivatives), dieldrin and HCB were detected in over 80% of 755 otter livers sampled. Concentrations of ∑PCB, ∑DDT and dieldrin in otter livers declined across the UK, but there was no significant time trend for ∑PCB-TEQ (WHO toxic equivalency, Van den Berg et al., 2006) or HCB. In general, higher concentrations were found in the midlands and eastern regions, and lowest concentrations in western regions. Concentrations of PCBs and HCB in otters increased near the coast, potentially reflecting higher pollutant levels in estuarine systems. Decades after legislative controls, concentrations of these legacy pollutants still pose a risk to otters and other freshwater predators, with spatially widespread exceedance of thresholds above which reproduction or survival has been reduced in related species.

BFRs (PBDEs and HBCDs) in freshwater species from Lake Trasimeno (Italy): The singular case of HBCDs in red swamp crayfish

Eighty-six samples belonging to five different species (crucian carp, Carassius carassius; European perch, Perca fluviatilis; tench, Tinca tinca; eel, Anguilla anguilla; red swamp crayfish, Procambarus clarkii) collected from Lake Trasimeno (Italy) were analyzed to assess polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs) contamination. The Trasimeno is the largest Italian peninsular lake located in Umbria (Central Italy), in a rural area with low anthropogenic impact. All the samples were analyzed by an in-house developed analytical procedure involving a single sample preparation with dual detection: Gas- and Liquid-Chromatography coupled to tandem Mass Spectrometry (GC-MS/MS for PBDEs and LC-MS/MS for HBCDs). BFRs levels in crucian carp, tench and European perch were negligible and mostly below quantification limits (LOQs). In eel, the species with the higher fat content, PBDE sum (15 congeners) ranged from 0.269 to 0.916 ng/g w.w. BDE-47, -100 and -154 accounted for roughly 57%, 16% and 11% of the PBDE sum, respectively, while BDE-99 (usually one of the most abundant congeners in biota), only for 3%. HBCDs (sum of α-, β-, γ-isomers) were found between 0.157 and 1.14 ng/g w.w. with α- as predominant isomer (92% of the sum), followed by γ- (5%) and β- (2%). Peculiar was the contamination in red swamp crayfish characterized by negligible PBDEs and very high HBCDs levels with a singular contamination pattern. In female pools (n = 9) the mean HBCDs sum was 0.150 ng/g w.w., while in males higher concentrations were measured (mean = 2.77 ng/g w.w.). A significant correlation seems to exist between the contamination level and the seasonal cycle only in male crayfish. Interestingly, among the HBCDs, the γ-isomer was the highest (67% of the total) while α- contributes only for 20%.

[Research progress on analytical methods for the determination of hexachlorobutadiene]

Hexachlorobutadiene (HCBD) is one of persistent organic pollutants (POPs) listed in Annex A and Annex C of the Stockholm Convention in 2015 and 2017, respectively. Research on the sources, environmental occurrences, and biological effects of HCBD has a great significance in controlling this newly added POPs. Sensitive and credible methods for the determination of HCBD are preconditions and form the basis for related research work. In recent years, many researchers have included HCBD as one of the analytes in monitoring or methodological studies. Based on the results of these studies, this paper reviews the research progress on analytical methods for the determination of HCBD and focuses on sample pretreatment methods for the analysis of HCBD in various matrices such as air, water, soil, sewage sludge, and biological tissues. The advantages and disadvantages of the methods are also compared to provide reference for further research in this field.For air samples, HCBD was usually collected by passing air through sorbent cartridges. Materials such as Tenax-TA, Carbosieve, Carbopack, Carboxen 1000, or their mixtures were used as the sorbent. HCBD was thermally desorbed and re-concentrated in a trap and finally transferred for instrumental analysis. Limits of detection (LODs) for HCBD in these methods were at the ng/m3 scale. Compared to sampling using pumps, passive air samplers (PAS) such as polyurethane foam PAS (PUF-PAS) do not require external power supply and are more convenient for sampling POPs in air at a large scale. The LOD of the sorbent-impregnated PUF PAS (SIP-PAS) method was much lower (0.03 pg/m3) than that of the PUF-PAS method (20 pg/m3). However, the sampling volumes in the SIP-PAS and PUF-PAS methods (-6 m3) calculated from the log KOA value of HCBD have significant uncertainty, and this must be confirmed in the future.For water samples, HCl or copper sulfate was added to the sample immediately after sampling to prevent any biological activities. HCBD can be extracted from water using methods such as the purge and trap method, liquid-liquid extraction (LLE) method, and solid phase extraction (SPE) method. Among these methods, SPE enabled the simultaneous extraction, purification, and concentration of trace HCBD in a single step. Recoveries of HCBD on Strata-X and Envi-Carb SPE cartridges (63%-64%) were higher than those on Envi-disk, Oasis HLB, and Strata-C18 cartridges (31%-46%). Drying is another key step for obtaining high recoveries of HCBD. Disk SPE involving the combination of a high-vacuum pump and a low-humidity atmosphere is an effective way to eliminate the residual water. In addition, a micro SPE method using functionalized polysulfone membranes as sorbents and employing ultrasonic desorption was developed for extracting HCBD from drinking water. The recovery of HCBD reached 102%, with a relative standard deviation (RSD) of 3.5%.For solid samples such as dust, soil, sediment, sewage sludge, fly ash, and biota tissue, multiple pretreatment methods were used in combination, owing to the more complex matrix. Freeze or air drying, grinding, and sieving of samples were commonly carried out before the extraction. Soxhlet extraction is a typical extraction method for HCBD; however, it requires many organic reagents and is time consuming. The accelerated solvent extraction (ASE) method requires a small amount of organic reagent, and the extraction can be performed rapidly. It was recently applied for the extraction of HCBD from solid samples under 10.34 MPa and at 100 ℃. Purification could be achieved simultaneously by mixing florisil materials with samples in the ASE pool. Nevertheless, employing the ASE methods widely is difficult because of their high costs. Ultrasonic-assisted extraction (UAE) has the same extraction efficiency for HCBD, with much lower costs compared to ASE, and is therefore adopted by most researchers. The type of extraction solvent, solid-to-liquid ratio, ultrasonic temperature, and power affect the extraction efficiency. Ultrasonic extraction at 30 ℃ and 200 W using 30 mL dichloromethane as the extraction solvent resulted in acceptable recoveries (64.0%-69.4%) of HCBD in 2 g fly ash. After extraction, a clean-up step is necessary for the extracts of solid samples. Column chromatography is frequently used for purification. The combined use of several columns or a multilayer column filled with florisil, silica gel, acid silica gel, or alumina can improve the elimination efficiency of interfering substances.Instrumental analysis for HCBD is mainly performed with a gas chromatograph equipped with a mass spectrometer operating in selected ion monitoring mode. DB-5MS, HP-5MS, HP-1, ZB-5MS, and BP-5 can be used as the chromatographic columns. Qualification ions and quantification ions include m/z 225, 223, 260, 227, 190, and 188. GC-MS using an electron ionization (EI) source was more sensitive to HCBD than GC-MS using a positive chemical ionization source (PCI) and atmospheric pressure chemical ionization source (APCI). Gas chromatography-tandem mass spectrometry (GC-MS/MS), gas chromatography-high-resolution mass spectrometry (GC-HRMS), and high-resolution gas chromatography-high-resolution mass spectrometry (HRGC-HRMS) have recently been used for the separation and determination of HCBD and various other organic pollutants. Instrumental detection limits for HCBD in GC-MS/MS, GC-HRMS, and HRGC-HRMS were more than ten times lower than that in GC-MS, indicating the remarkable application potential of these high-performance instruments in HCBD analysis.

A review of sources, environmental occurrences and human exposure risks of hexachlorobutadiene and its association with some other chlorinated organics

Research on hexachlorobutadiene (HCBD) has increased since its listing in the Stockholm Convention on Persistent Organic Pollutants in 2011. However, thorough reports on recent data regarding this topic are lacking. Moreover, potential associations between HCBD and some chlorinated organics have usually been ignored in previous research. In this review, possible formation pathways and sources, current environmental occurrences and human exposure risks of HCBD are discussed, as well as the association with several organochlorine compounds. The results reveal that unintentional production and emission from industrial activities and waste treatments are the main sources of HCBD. Similar precursors are found for HCBD and chlorobenzenes, indicating the presence of common sources. Although recent data indicates that levels of HCBD in the environment are generally low, risks from human exposure to HCBD, together with other pollutants, may be high. More attention in the future needs to be paid to the mixed contamination of HCBD and other pollutants from common sources.

PBDEs and PCBs in terrestrial ecosystems of the Victoria Land, Antarctica

The Victoria Land (East Antarctica) is characterized by the presence of lakes and ponds where rare water is found during the Summer months. These freshwater ecosystems are an important resource for migrating seabirds that use them and leave there their droppings and feathers, contributing to enrich the water with organic matter. Persistent organic pollutants (POPs) are long-range transported to polar regions and their detection in the Antarctic ecosystems date back to the 1960s. Most studies have been related to POP concentrations in marine environment, and terrestrial ecosystems have been poorly investigated. This study reports the concentration of PBDEs (23 congeners) and PCBs (21 among non-, mono-, di-, and ortho congeners) in lake sediment, soil and vegetation mat (community of algae, cyanobacteria, bryophites) collected close to six lakes in the Victoria Land (74°31'S-74°97'S, 165°07'E-162°51'E): Edmonson Point 14 and 15A, Carezza, Enigma, Tarn Flat 20, Inexpressible Island 10B. The ∑PBDEs averaged 0.09-0.28 ng/g and BDEs 28, 47 and 154 were higher in mat and soils, while BDEs 183 and 47 in sediment samples. PCBs ranged <0.003-0.807 ng/g and congeners nos. 114, 138, and 187 were the most abundant. In addition, TEQs were derived for the non-and mono-ortho PCBs detected and values were very low in each matrix (0.010 pg/g in the soil, 0.012 pg/g in sediment and mat). The long-range atmospheric transport can be confirmed as the most important POP source in Antarctica, although the scientific stations and seabird colonies may be potential local sources and contribute to contaminant release.

Recently listed Stockholm convention POPs: Analytical methodology, occurrence in food and dietary exposure

In recent years, the Stockholm Convention has listed an additional set of persistent organic pollutants (POPs) for elimination or restricted use/release. Data on the occurrence of these contaminants in food is scarce. Validated analytical methodology was developed to investigate the occurrence of hexachlorobutadiene (HCBD), pentachlorobenzene (PCBz), hexachlorobenzene (HCB) pentachlorophenol (PCP) and polychlorinated naphthalenes (PCNs) in 120 retail foods and 19 total diet study samples. The foods covered the range of commonly consumed dietary items including dairy products, eggs (hen and other species), poultry, meat, fish, vegetables, etc. HCBD showed a low frequency of detection, whereas PCBz, HCB and PCNs occurred in most samples (ranges: <0.01 to 0.19 μg/kg; <0.01 to 3.16 μg/kg and 0.1 to 166 ng ΣPCNs/kg respectively). PCP (<0.01 to 1.9 μg/kg) was detected more frequently in meat products, offal and eggs. Fish, shellfish, eggs from all species, animal fats, meat, offal and meat products showed higher contamination levels, which is normal when investigating lipophilic POPs. These levels of occurrence are similar to more recently reported literature levels but perhaps lower, relative to historic data. This is not unexpected, given the restrictions/limitations on these chemicals within the UK and Western Europe. The estimated human exposure to population groups through dietary intake is correspondingly low and based on current toxicological knowledge, the levels in the examined samples do not suggest a cause for health concern. The data also provide a current baseline for HCBD, PCBz and PCP, and update existing data for PCN and HCB occurrence in foods.

Persistent Organic Pollutant Burden, Experimental POP Exposure, and Tissue Properties Affect Metabolic Profiles of Blubber from Gray Seal Pups

Persistent organic pollutants (POPs) are toxic, ubiquitous, resist breakdown, bioaccumulate in living tissue, and biomagnify in food webs. POPs can also alter energy balance in humans and wildlife. Marine mammals experience high POP concentrations, but consequences for their tissue metabolic characteristics are unknown. We used blubber explants from wild, gray seal ( Halichoerus grypus) pups to examine impacts of intrinsic tissue POP burden and acute experimental POP exposure on adipose metabolic characteristics. Glucose use, lactate production, and lipolytic rate differed between matched inner and outer blubber explants from the same individuals and between feeding and natural fasting. Glucose use decreased with blubber dioxin-like PCBs (DL-PCB) and increased with acute experimental POP exposure. Lactate production increased with DL-PCBs during feeding, but decreased with DL-PCBs during fasting. Lipolytic rate increased with blubber dichlorodiphenyltrichloroethane and its metabolites (DDX) in fasting animals, but declined with DDX when animals were feeding. Our data show that POP burdens are high enough in seal pups to alter adipose function early in life, when fat deposition and mobilization are vital. Such POP-induced alterations to adipose metabolic properties may significantly alter energy balance regulation in marine top predators, with the potential for long-term impacts on fitness and survival.

3D numerical modelling of a pulsed pumping process of a large DNAPL pool: In situ pilot-scale case study of hexachlorobutadiene in a keyed enclosure

Remediation of dense non-aqueous phase liquids (DNAPLs) represents a challenging issue because of their persistent behaviour in the environment. This pilot-scale study investigates, by means of in situ experiments and numerical modelling, the feasibility of the pulsed pumping process of a large amount of a DNAPL in an alluvial aquifer. The main compound of the DNAPL is hexachlorobutadiene (HCBD), added in 2015 to the persistent organic pollutants list (POP). A low-permeability keyed enclosure was built at the location of the DNAPL source zone in order to isolate a finite volume of soil and a 3-month pulsed pumping process was applied inside the enclosure to exclusively extract the DNAPL. The water/DNAPL interface elevation at both the pumping well and an observation well was recorded. The cumulated pumped volume of DNAPL was also monitored. A total volume of about 20 m³ of pure DNAPL was recovered since no water was extracted during the process. The three-dimensional and multiphase flow simulator TMVOC was used and a conceptual model was elaborated and generated with the pre/post-processing tool mView. Numerical simulations reproduce the pulsed pumping process and show an excellent match between simulated and field data of DNAPL cumulated pumped volume and a reasonable agreement between modelled and observed data for the evolution of the water/DNAPL interface elevations at the two wells. This study offers a new perspective in remediation since DNAPL pumping system optimisation may be performed where a large amount of DNAPL is encountered.

The experimental observation, mechanism and kinetic studies on the reaction of hexachloro-1,3-butadiene initiated by typical atmospheric oxidants

Hexachloro-1,3-butadiene (HCBD) is a persistent organic pollutant in the environment. When its samples were collected and observed, the levels of HCBD in its source and high mountains are higher than in urban cities, oil factories and countryside. The density functional theory is applied to the degradation mechanism of HCBD with Cl, NO₃, HO₂, OH and O₃. Those reactions are optimized and calculated at two carbon sites of double bonds, and then the subsequent reactions of the OH-initiated intermediates with O₂ and NO are taken as examples. Ozonization reactions of HCBD including the formation of primary and secondary ozonides are investigated. The Criegee intermediates created in the ozonization reactions can react with O₂, SO₂, NO₂ and H₂O. Reaction rate constants of the Cl, NO₃, HO₂, OH and O₃ initiated reactions with HCBD are calculated within 200 to 400 K with the transition state theory method, and the rate constants of the Cl, NO₃, HO₂, OH and O₃ at 298.15 K are 4.51 × 10^-13, 1.32 × 10^-20, 4.33 × 10^-29, 6.33 × 10^-16, 5.80 × 10^-27 cm³ molecule^-1 s^-1, respectively. The reactions of OH and Cl radicals with HCBD are more important than those of NO₃, HO₂ and O₃ according to the reaction rate branching ratio. Both the temperature and reaction rate could change with the height.

Perinatal programming of depressive-like behavior by inflammation in adult offspring mice whose mothers were fed polluted eels: Gender selective effects

Several lines of evidence indicate that early-life inflammation may predispose to mental illness, including depression, in later-life. We investigated the impact of perinatal exposure to polluted eels on neonatal, postnatal, and adult brain inflammation, and on the resignation behavior of male and female adult offspring mice. The effects of maternal standard diet (laboratory food) were compared to the same diet enriched with low, intermediate, or highly polluted eels. Brain inflammatory markers including cytokines were assessed in offspring mice on the day of birth (i.e., on the postnatal day-PND 1), upon weaning (PND 21) and at adulthood (PND 100). Plasma myeloperoxidase and corticosterone levels were evaluated at PND 100. Immobility behavior of offspring was assessed in adulthood (i.e., at PNDs 95-100), using the tail suspension and forced swimming tests. Chronic brain inflammation was found in male and female offspring mice compared to controls, as assessed at PNDs 1, 21, and 100. The level of myeloperoxidase was found to be significantly higher in both adult males and females vs. control offspring. However, high corticosterone levels were only found in male offspring mice that were perinatally exposed to eels, suggesting a gender-selective dysregulation of the adult hypothalamic-pituitaryadrenal (HPA) axis. Gender-specific differences were also detected in adulthood in regard to offspring resignation behavior. Thus, compared to controls, males, but not females, whose mothers were fed eels during pregnancy and lactation exhibited a depressive-like behavior in adult age in both behavioral models of depression. Depressive symptoms were more pronounced in male mice perinatally exposed to either intermediate or highly polluted eels than those exposed to only lowly polluted eels. Our results indicate that early-life inflammatory insult is a plausible causative factor that induces the depressive phenotype exhibited by male adult offspring mice, most likely through a gender-specific HPA axis enhanced activation.

Legacy and emerging halogenated organic pollutants in marine organisms from the Pearl River Estuary, South China

A suite of legacy and emerging halogenated organic pollutants (HOPs) were measured in marine organisms (coastal fish and invertebrates) from the Pearl River Estuary, South China, to investigate the current contamination status after the Stockholm Convention was implemented in China. Dichlorodiphenyltrichloroethane and its metabolites (DDTs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) were detected in all samples at concentrations of 54-1500, 16-700, and 0.56-59ng/g lipid weight, respectively. Dechlorane Plus (DP), decabromodiphenyl ethane (DBDPE), 2,3,5,6-tetrabromo-p-xylene (pTBX), and pentabromotoluene (PBT) were also found at concentrations of ND (non-detectable) to 37ng/g lipid weight. The concentrations of these investigated contaminants in the present study were at moderate levels, as compared with those reported in other regions. Significant interspecies differences were found in the levels of DDTs, PCBs, PBDEs and the alternative halogenated flame retardants (AHFRs). DDTs were the predominant HOPs in those species and represented >50% of the total HOPs, followed by PCBs, PBDEs, and AHFRs. The total estimated daily intakes (EDIs) of DDTs, PCBs, PBDEs, and AHFRs were 28, 12, 1.0, and 0.18 (ng/kg)/d, respectively, via seafood consumption. These concentrations are not expected to pose health risks to humans.

Persistent organic pollutants in muscle of fish collected from the Nové Mlýny reservoir in Southern Moravia, Czech Republic

The aim of the present study was to investigate the content of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in muscle tissues of fish, i.e. carp (Cyprinus carpio, L.), bream (Abramis brama, L.) and pike perch (Stizostedion lucioperca, L.) from the middle Nové Mlýny reservoir and compare our results with previous corresponding studies. Samples were analysed by gas chromatography with ion trap tandem mass spectrometry. The highest contents of all pollutants were determined in muscle tissue of bream. The analysis of HCHs showed that β-HCH was the most abundant. PCB congener 28 was evaluated as the predominant PCB congener. The metabolite p,p'-DDE exhibited the highest concentration of all the monitored metabolites. The monitoring confirmed significantly (P < 0.01) higher concentrations of OCP and PCB in muscle of bream compared to carp and pike perch. The contents of pollutants in our study were found to be lower in comparison to the findings of some previous studies.

Polycyclic aromatic hydrocarbons, polychlorinated biphenyls and organochlorine pesticides in European hake (Merluccius merluccius) muscle from the Western Mediterranean Sea

Polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs) were quantified in muscle tissue of European hake, an ecologically and commercially important species. Samples were collected from the Western Mediterranean, in seven different stations at different depths and a batch was bought in a local market. PCBs are the dominant pollutants, but the overall concentrations do not show significant differences between the different specimens analyzed from various locations, with the exception of the concentration of PCBs at a shallow station close to the River Besòs mouth. This probably suggests that generally the pollutants in hake from the Western Mediterranean derive from historical and non-point sources. The occurrence of pollutants is widespread in the samples but their concentration is below recommended legal limits for fish or other foodstuffs.

Lipid increases in European eel (Anguilla anguilla) in Scotland 1986-2008: an assessment of physical parameters and the influence of organic pollutants

Recruitment of the European eel (Anguilla anguilla) has fallen steadily in recent decades, with current levels understood to be at around 5% of those in the 1970s, and the species is now widely recognised as being endangered. Changes in ocean currents, climate shifts, habitat loss, overfishing, barriers to migration, increased predation, plastic litter and exposure to chemicals have all been postulated as potential causative factors. Several studies have shown a general decline in eel quality (lower lipid content and body condition) over time that may be linked to reduced reproductive success. In this study, data from an eel sampling campaign in 1987 are compared with recent data (2004-2008) for eels in Scotland to assess any temporal changes in eel quality indicators and also to assess any links between current levels of chemical exposure and eel quality. Mean lipid levels, as a percentage of wet muscle mass, were higher in 2004-2008 (37 ± 1.9% SE) than in 1986 (21 ± 0.9% SE). By contrast, mean body condition index (K) was slightly lower in the latter period. Considering the 2004-2008 samples, significant inter-site variation was observed for condition index K, while intra-site variation was observed for lipid content and physical parameters relative to age (i.e. mass/age, length/age and lipid/age ratios); however, the variations observed could not be linked to differences in chemical body burdens, indicating that no chemical impacts on the parameters assessed are discernible during the continental life stage of eels in Scotland.

An eight year (2005-2013) temporal trend of halogenated organic pollutants in fish from the Pearl River Estuary, South China

Dichlorodiphenyltrichloroethane and its metabolites (DDTs), hexachlorocyclohexanes (HCHs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), dechlorane plus (DP), 2,3,5,6-tetrabromo-p-xylene (pTBX) and pentabromotoluene (PBT) were measured in baby croaker (Collichthys lucidus) and mullet (Osteomugil ophuyseni) collected in 2005 and 2013 from the Pearl River Estuary. DDTs, HCHs, PCBs, and PBDEs were detected in two fish species at concentrations of 150-8100, 1.4-120, 22-560, 2.2-280 ng/g lipid wt., respectively. The levels of these chemicals were significantly lower in 2013 than in 2005. The compositions for DDTs, HCHs, and PBDEs in 2013 differed from those in 2005, indicating source changes between the two sampling periods. DP, pTBX and PBT were detected at concentrations of ND-130 ng/g lipid wt. No clear temporal trends were found for these contaminants. Overall, these results indicated the effectiveness of regulations and source controls in substantively reducing inputs of these contaminants to the Pearl River Estuary.

Occurrence of POPs and other persistent organic contaminants in the European eel (Anguilla anguilla) from the Loire estuary, France

The chemical contamination of the Loire estuary by three classes of persistent organic pollutants (POPs): the polychlorinated biphenyls (PCBs), the polybrominated diphenyl ethers (PBDEs) and the perfluorinated and polyfluorinated alkyl substances (PFAS), and three families of organic contaminants, the alkylphenols (APs), the polycyclic aromatic hydrocarbon metabolites (OH-PAHs) and the bisphenol A (BPA) were investigated in the muscles and bile of European eel (Anguilla anguilla). Yellow eels (n=30) were caught in three different points along the estuary to highlight variations between sites and sources of contaminations. Silver eels (n=15) were also studied to compare contaminant impregnation between different life stages of the species. Average concentrations in the muscles of the eel ranged between: 857 and 4358 ng/gLW for the PCBs, 26 and 46 ng/gLW for the PBDEs, 130 and 1293 ng/gLW for the PFAS; and in bile: 31 and 286 μg/g protein for the APs, 9 and 26 μg/g protein for the OH-PAHs and ND-1213 μg/g protein for the BPA. Among PCBs, PCB 153 (40% contribution to the sum of PCBs) was predominant in all eel muscles. PBDE 47 (60%) was the most predominant PBDE congeners, while perfluorooctanesulfonic acid (85%) was the most widely detected PFAS. For APs, 4p-nonylphenol (91%) was the most abundant and for the OH-PAHs, it was 1OH-Pyrene (63%). All the eels exceeded the environmental quality standards (EQS) for biota for the PBDEs and about 75% were higher than the EQS specific to PFOS. Finally, 20% of the analyzed eels presented TEQ concentrations above the maximum limits for lipid-rich species. These results supplied new data on the occurrence, levels, and patterns of 53 organic chemicals in the eels from the Loire estuary and they highlighted the need of further investigations focused notably on the potential effects of these chemicals on this species and their analysis in the water and sediments of the estuary.

PCB and organochlorine pesticide burden in eels in the lower Thames River (UK)

Thirty-five European eels (Anguilla anguilla), caught in 2007 in the river Thames upstream and downstream of both London and the tidal limit, were analysed for PCBs and organochlorine pesticides. Most chemicals were detectable in every fish, although they have been banned or severely restricted for many years. In general, the tidal eels were more contaminated than upstream ones, which was related to their higher lipid contents. The ICES7 indicator PCB concentrations ranged overall from 4.2 to 124μgkg(-1) fresh weight with averages of 33 and 56μgkg(-1) for the upstream and tidal eels; 3.5-104μgkg(-1), average 26 and 48μgkg(-1) of that were ICES6 PCBs. Total DDT was on average 16μgkg(-1) (1.7-38μgkg(-1)) upstream and 18μgkg(-1) (8.6-35μgkg(-1)) downstream with about half of that provided by pp'DDE. Lindane (γ-HCH) was found at up to 2.8μgkg(-1) (averages 0.58 and 1.1μgkg(-1) upstream and downstream) and hexachlorobenzene (HCB) was on average 1.9 and 2.5μgkg(-1) in the two groups with a maximum of 6.4μgkg(-1) in each. Therefore all individuals passed the European Environmental Quality Standard (EQS) of 10μgkg(-1) for HCB. PCB contamination was fairly typical for recent UK eel data, whilst DDE and lindane concentrations were lower than most previous UK eel studies, perhaps reflecting a downward trend. Although not as highly contaminated as some eels from previous UK and European studies, the presence of so many of these chemicals, with their known health effects may represent a stress for the fish or higher predators, such as birds.

The occurrence of organic contaminants in European eel (Anguilla anguilla) in Poland: an environmental quality assessment

The objective of the present study was to provide information on the levels of pollutants in the tissues of eels caught in Polish waters. The contaminants included in the study are those which have not yet been widely studied in eel stocks, but which arouse concern in relation to the environment. An overview of the pollutant levels in eels caught in other European waters was also conducted. The results are evaluated in terms of environmental quality and consumer health. The mean concentrations of ΣPBDEs and ΣHBCDs in muscles of eels sampled in Polish waters were between 1 and 2 ng g(-1) ww. The mean TBT concentrations were between 2 and 4 ng g(-1)ww with the exception of samples from the Szczecin Lagoon, in which the mean TBT concentration was about tenfold higher.

A review of new and current-use contaminants in the Arctic environment: evidence of long-range transport and indications of bioaccumulation

Systematic monitoring of persistent organic pollutants (POPs) in the Arctic has been conducted for several years, in combination with assessments of POP levels in the Arctic, POP exposure and biological effects. Meanwhile, environmental research continues to detect new contaminants some of which could be potential new Arctic pollutants. This study summarizes the empirical evidence that is currently available of those compounds in the Arctic that are not commonly included in chemical monitoring programmes. The study has focused on novel flame retardants, e.g. alternatives to the banned polybrominated diphenyl ethers (PBDEs), current-use pesticides and various other compounds, i.e. synthetic musk compounds, siloxanes, phthalic acid esters and halogenated compounds like hexachlorobutadiene, octachlorostyrene, pentachlorobenzene and polychlorinated naphthalenes. For a number of novel brominated flame retardants, e.g. 2,3-bibromopropyl-2,4,6-tribromophenyl ether (DPTE), bis(2-ethylhexyl)tetrabromophthalate (TBPH), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (TBB), 1,2-bis(2,4,6-tribromophenoxy)-ethane (BTBPE), decabromodiphenyl ethane (DBDPE), pentabromoethylbenzene (PBEB) and hexabromobenzene (HBBz), transport to the Arctic has been documented, but evidence of bioaccumulation is sparse and ambiguous. For short-chain chlorinated paraffins and dechlorane plus, however, increasing evidence shows both long-range transport and bioaccumulation. Ice cores have documented increasing concentrations of some current-use pesticides, e.g. chlorpyrifos, endosulfan and trifluralin, and bioaccumulation has been observed for pentachloroanisole, chorpyrifos, endosulfan and metoxychlor, however, the question of biomagnification remains unanswered.

Evaluating the exchange of DDTs between sediment and water in a major lake in North China

A large-scale sampling program was conducted to simultaneously collect surface water, overlying water, pore water, and sediment samples at monthly intervals between March and December 2010 from Baiyangdian Lake, North China to assess the distribution of DDTs and determine the net direction of sediment-water exchange. Total DDT concentrations ranged 2.36-22.4 ng/L, 0.72-21.9 ng/L, 2.25-33.7 ng/L, and 4.42-7.29 ng/g in surface water, overlying water, pore water, and sediments, respectively, which were at the intermediate levels compared to those of other area around the world. Seasonal variations of DDTs were featured by higher concentration in summer. This was likely associated with (a) the increase of land runoff in the summer and (b) application of dicofol and DDT-containing antifouling paints for ships in summer. Sediment-water fugacity ratios of the DDT isomers were used to predict the direction of the sediment-water exchange of these isomers. The sediment-surface water, sediment-overlying water, and sediment-pore water fugacity ratios of DDT isomers averaged 0.34, 0.44, and 0.1, which are significantly lower than the equilibrium status (1.0), suggesting that the net flux direction were from the water to sediment and the sediment acted as a sink for the DDTs. The difference of DDT concentrations between sediment and water samples was found to be an important factor affecting the diffusion of DDT from the water to sediment.

Are persistent organic pollutants and metals in eel muscle predictive for the ecological water quality?

Relationships between the presence of PCBs, OCPs and metals in aquatic ecosystems and the ecological water quality were investigated by combining datasets of long-term monitoring of chemicals in European eel (Anguilla anguilla, N = 1156) in Flanders (Belgium) and the Ecological Quality Ratio (EQR), based on the assessment of fish assemblages at 185 locations. For most pollutants, EQR scores were lower when pollutant levels were higher. Threshold concentrations for a good quality could be formulated for PCB's, most metals and OCPs. Mixed models suggested that the ecological water quality was significantly correlated with the presence of PCBs. However, the low R(2) indicates that other environmental pressures may significantly influence the biotic integrity of fish communities. Empirical data and their analyses are essential to enable defining threshold values of bioaccumulated levels to allow better protection of the aquatic environment and its biota through associated food webs as demanded by the Water Framework Directive.

Levels and distributions of hexachlorobutadiene and three chlorobenzenes in biosolids from wastewater treatment plants and in soils within and surrounding a chemical plant in China

Although hexachlorobutadiene (HCBD) was recently proposed as a candidate persistent organic pollutant (POP) under the Stockholm Convention, information about its environmental levels and distributions is still very limited. In this work, HCBD was determined in the sewage sludge from 37 wastewater treatment plants (WWTPs) in 23 cities and 17 soils near a chemical plant in China. Three chlorobenzenes (CBs) (1,2,4-trichlorobenzene, 1,2,4,5-tetrachlorobenzene, and hexachlorobenzene) were simultaneously studied to help better understand the environmental behavior of HCBD. Concentrations of HCBD in sludge samples ranged from <0.03 to 74.3 ng/g dry weight (dw) with a median value of 0.30 ng/g dw, which was lower than those of the three CBs. Levels of HCBD were not correlated with capacity of the WWTPs and total organic carbon. For soils, high level of HCBD was found in the sample within the plant, with a rapid decreasing concentration trend with the increase of distance from the plant. It was suspected that releasing as a byproduct during manufacturing of chlorinated chemicals was the primary source of HCBD in the studied location. Further risk assessment indicated that the environmental risk of HCBD to soil organisms and the health risk to employees were very low through soil exposure within the plant.

The presence of EU priority substances mercury, hexachlorobenzene, hexachlorobutadiene and PBDEs in wild fish from four English rivers

Since 2007 about 200 to 300 fish per year--generally roach (Rutilus rutilus) also a few bleak (Alburnus alburnus) and eels (Anguilla anguilla)--have been collected from a number of English river sites and stored at -80°C to build up a Fish Tissue Archive as a resource for the monitoring of pollutants. Some of the fish from the Fish Tissue Archive from the years 2007-2011 were analyzed for substances in current and proposed European legislation regarding environmental quality standards (EQS) in biota. It was found that mercury exceeded the EU EQS of 20 μg/kg in 79% of samples with an average and median of 31 and 29 μg/kg. The legacy fungicide hexachlorobenzene (HCB) was below the EQS of 10 μg/kg in all fish analyzed, with a maximum of 6 μg/kg in some eels. The legacy solvent hexachlorobutadiene (HCBD) was below the EQS of 55 μg/kg, being <0.2 μg/kg in all samples where it was measured. The sums of six polybrominated diphenyl ethers (PBDEs) were several orders of magnitude higher than the new proposed 0.0085 μg/kg biota EQS. This study showed that the regular collection and analysis of whole body homogenate samples of relatively small native pelagic fish is suitable for the monitoring of contaminants capable of bioaccumulation. With regard to current or proposed EQS for EU countries, mercury and potentially PBDE in fish are of some concern in these English rivers.

Occurrence of brominated flame retardants and perfluoroalkyl substances in fish from the Czech aquatic ecosystem

This study reports results of analysis of various groups of halogenated compounds, including brominated flame retardants (BFRs), such as polybrominated diphenylethers (PBDEs), hexabromocyclododecane (HBCD), tetrabromobisphenol A (TBBPA) and perfluoroalkyl substances (PFASs) in 48 fish samples collected in eight localities from the Czech Republic. In this survey, identification of potential sources of these chemicals was also performed; therefore several sampling sites located in highly industrialized areas were also selected. Perfluorooctanesulfonate (PFOS) was dominating in all tested fish samples. Generally, the content of ∑BFRs was significantly lower, i.e. in the range of 0.21-19.9 μg/kg wet weight, ww (median value 2.37 μg/kg ww) compared to the concentration of ∑PFASs that was in the range of 0.15-877 μg/kg ww (median value 8.5 μg/kg ww). The extremely high content of PFOS (842 μg/kg ww) was found in fish muscle tissue from the locality situated on the Bílina River, where chemical industry is located. This concentration was comparable to those found in similar highly industrialized areas worldwide.

Identification of selected organic contaminants in streams associated with agricultural activities and comparison between autosampling and silicone rubber passive sampling

This study evaluates the potential of silicone rubber passive sampling devices (SR-PSDs) as a suitable alternative to automatic water samplers (autosamplers) for the preliminary identification of a wide range of organic contaminants in freshwater systems. The field performance of SR-PSDs deployed at three sites on two streams of an agricultural catchment area in North East (NE) Scotland, United Kingdom (UK) was assessed concurrently with composite water samples collected from two of the sites using autosamplers. The analytical suite consisted of selected plant protection products (PPPs; commonly referred to collectively as 'pesticides'), including 47 pesticides and a separate sub-category of 22 acid/urea herbicides. Of these, a total of 54 substances, comprising 46 pesticides and 8 urea herbicides were detected in at least one of the SR samplers. All but 6 of these SR-PSD detected substances were quantifiable. By comparison, a total of 25 substances comprising 3 pesticides and 22 acid/urea herbicides were detected in the composite water samples, of which only 8 acid/urea herbicides were quantifiable. The larger number and chemical classes of compounds detected and quantified via passive sampling reflect the lower limits of detection achieved by this device when compared to autosamplers. The determination of dissolved concentrations of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) added to the information on contaminant pressures at each site, allowing assessment of the reliability of SR-PSDs in freshwater systems and the identification of possible contaminant sources. The study demonstrated the utility of SR-PSDs for detecting and semi-quantifying low concentrations of analytes, including those which hitherto have not been measured in the catchment area and also some pesticides that are no longer approved for agricultural use in the UK and EU. The SR-PSD approach can thus provide a better understanding and clearer picture of the use and presence of organic contaminants within catchments.

PCBs contamination does not alter aerobic metabolism and tolerance to hypoxia of juvenile sole (Solea solea L. 1758)

Coastal habitats play a major role as nurseries for many fish species; however, they are also submitted to pollutants and oxygen fluctuations. Fry's concept of metabolic scope for activity was used to evaluate the effect of polychlorinated biphenyls (PCBs) on the aerobic metabolism in juvenile common sole (0-1 year old). Aerobic metabolic scope (AMS) in control and PCB-contaminated fish via food pathway was determined using respirometry techniques. Furthermore, the hypoxia tolerance in control and PCB-contaminated fish was evaluated by assessing their critical oxygen concentration (O(2crit)). Our results showed that while PCB-contaminated fish were able to maintain a constant AMS and O(2crit), PCBs tend to affect their aerobic metabolism by acting on maximal oxygen consumption (MO(2max)) in hypoxia and standard metabolic rate, but only at the highest PCB concentration between 30 and 60 days of exposure. In conclusion, we can hypothetise that the tested PCB-exposures may not impair the tolerance to hypoxia and the survival of common sole in their natural environment.

Evaluating the sediment-water exchange of hexachlorocyclohexanes (HCHs) in a major lake in North China

A large-scale sampling program was conducted to simultaneously collect surface water, overlying water, pore water and sediment samples at monthly intervals from March to December 2010 from the Baiyangdian Lake, North China to assess the distribution of hexachlorocyclohexanes (HCHs) and determine the net direction of sediment-water exchange. Total HCHs concentrations ranged from 6.30-53.90 ng L (-1), 16.59-148.48 ng L(-1), 247.93-459.07 ng L (-1) and 3.60-12.50 ng g(-1) in surface water, overlying water, pore water and sediments, respectively, which was at the intermediate level compared to those of other areas in China. Seasonal variations of HCHs were featured by lower concentrations in April, July and November due to the dilution of HCHs caused by a great deal of fresh water being allocated to the Baiyangdian Lake in these months. Sediment-water fugacity ratios of the HCH isomers were used to predict the direction of the sediment-water exchange of these isomers. The sediment-surface water and sediment-overlying water fugacity ratios of HCH isomers averaged 11.4 and 3.0, which is significantly greater than the equilibrium status (1.0), suggesting that the net flux directions were from the sediment to water and the sediment acted as a secondary source to the water. Sediment-pore water fugacity ratios indicated near equilibrium or escape from pore water to sediment, depending on the isomer and sampling time. The difference of HCH concentrations between sediment and water samples were found to be an important factor affecting the diffusion of HCH from the sediment to water.

Contamination, parasitism and condition of Anguilla anguilla in three Italian stocks

In conjunction with habitat loss and overfishing, pollution and parasitism are believed to be relevant causes of collapse of Anguilla, as these can affect eel swimming ability and the development of gonads and embryos. The present study investigated Persistent Organic Pollutant (POP) concentrations, infection levels of Anguillicoloides crassus, lipid content and gonad abnormalities in eels sampled in 2007-2008 in three Italian water bodies (Caprolace Lake, Lesina Lagoon and Tevere River) that vary in salinity, trophic condition, contamination level and fishing pressure. Our analysis revealed that low-to-moderate levels of contamination and parasitism were not associated with gonad abnormalities in Caprolace Lake and Lesina Lagoon. On the contrary, POP concentrations and abundances of swim bladder nematodes were remarkably high in eels from the heavily urbanized Tevere River and were associated with significant gonad and swim bladder alterations. Contamination and infestation levels were so high to potentially impair spawner successful migration and reproduction. POP concentrations in Tevere eels also exceeded levels considered safe for food consumption. Though marginally contaminated, eels from the oligotrophic Caprolace Lake were in critical health condition: their lipid reserve was so low as to be considered insufficient to sustain the energetic costs of the transoceanic migration. Lesina eel stock was the only one displaying relatively good quality but here spawner abundance is likely limited by overfishing. Our results suggest that multiple stressors may potentially affect eel reproductive success. More definitive studies are needed to assess whether health effects caused by these multiple stressors are additive, compensatory or synergistic.

Investigating the significance of dissolved organic contaminants in aquatic environments: coupling passive sampling with in vitro bioassays

We investigated the feasibility of coupling passive sampling and in vitro bioassay techniques for both chemical and ecotoxicological assessment of complex mixtures of organic contaminants in water. Silicone rubber passive sampling devices (SR-PSDs) were deployed for 8-9 weeks in four streams and an estuary of an agricultural catchment in North East (NE) Scotland. Extracts from the SR-PSDs were analysed for freely dissolved hydrophobic organic contaminants (HOCs) and screened for wide range of pesticides. The total concentrations of dissolved PAHs (∑PAH(40), parent and branched) in the water column of the catchment varied from 38 to 69 ng L(-1), whilst PCBs (∑PCB(32)) ranged 0.02-0.06 ng L(-1). A number and level of pesticides and acid/urea herbicides of varying hydrophobicity (logK(OW)s ~2.25 to ~5.31) were also detected in the SR extracts, indicating their occurrence in the catchment. The acute toxicity and EROD induction potentials of SR extracts from the study sites were evaluated with rainbow trout liver (Oncorhynchus mykiss; RTL-W1) cell line. Acute cytotoxicity was not observed in cells following 48 h exposure to the SR extracts using neutral red uptake assay as endpoint. But, on a sublethal level, for every site, statistically significant EROD activity was observed to some degree following 72 h exposure to extracts, indicating the presence of compounds with dioxin-like effect that are bioavailable to aquatic organisms in the water bodies of the catchment. Importantly, only a small fraction of the EROD induction could be attributed to the PAHs and PCBs that were determined. This preliminary study demonstrates that the coupling of silicone rubber passive sampling techniques with in vitro bioassays is feasible and offers a cost effective early warning signal on water quality deterioration.

Polybrominated diphenyl ethers fate in China: a review with an emphasis on environmental contamination levels, human exposure and regulation

Because of their highly effective flame-retardant capability, polybrominated diphenyl ethers (PBDEs) have been extensively used as flame retardants in consumer goods. However, compelling evidence shows that many congeners of PBDEs have been accumulating in the environment, in biota and in human populations worldwide. In China, although octabrominated diphenyl ether (octaBDE) has never been produced or used, pentabrominated diphenyl ether (pentaBDE) and decabrominated diphenyl ether (decaBDE) have been produced and used in large quantities. In the face of increasing evidence about PBDE pollution and the adoption of international conventions, there is a growing push for China to develop more stringent methods of managing PBDE waste. This paper summarizes the information about PBDE production and application, describes the flame-retarding mechanism, and then reviews the toxicity and levels of PBDEs in China's environmental media and human tissues. Based on international regulations on PBDEs, the paper finally puts forward some suggestions for Chinese policy making and for self-regulation within the flame retardant industry.

Occurrence of halogenated contaminants in fish from selected river localities and ponds in the Czech Republic

The occurrence of organohalogenated compounds including major persistent chlorinated pollutants, such as polychlorinated biphenyls (PCBs) and DDT and its metabolites, brominated flame retardants (BFRs), represented by polybrominated diphenylethers (PBDEs) and hexabromocyclododecane (HBCD), together with currently widely discussed perfluorinated compounds (PFCs), mainly perfluorooctane sulfonic acid was monitored in several fish species collected from Czech rivers. Eleven sampling locations in highly industrialized areas were chosen. In addition, wild species of 14 farmed fish (grown in dedicated ponds) were also analysed. With respect to the contamination in different areas, chlorinated chemicals were dominant. PCBs and DDTs ranged from 4.8 to 211 and 2 to 791 μg/kg wet weight, respectively. Concentrations of BFRs and PFCs were significantly lower and ranged from 0.6 to 10.2 and 0.9 to 62 μg/kg wet weight, respectively. The highest levels of target analyte groups were found in fish muscle tissue in localities situated on the lower part of the Elbe River: Levels of DDT, HCB, PBDEs, and perfluorooctane sulfonic acid (PFOS) were as high as 791, 77.6, 14.4 and 193 μg/kg wet weight, respectively, in Usti nad Labem and in the sample originated from the confluence of Elbe with Bilina River; a sum of PCBs at a level of 211 μg/kg was detected.

The European eel quality database: towards a pan-European monitoring of eel quality

The stocks of the European eel Anguilla anguilla are in decline and there is an increasing awareness that poor health status due to contaminants and/or diseases might be a key element in this decline and might be a hindrance to recovery. Many countries have started compiling data on the health status of eels in their water bodies. Objectives for these monitoring actions are diverse and there is a large amount of information collected by EU member countries. However, this information is widely scattered over Europe in agencies, institutes or universities. As there is a growing need to collect and report on data on the health status of the eel on international level, the Joint EIFAC/ICES Working Group on Eels initiated in September 2007 the set up of an European Eel Quality Database to collect recent data of contaminants and diseases over the distribution area of the eel. This paper describes the aim, the set up and future development of the database in order to give it greater publicity and to call on scientists or managers to submit data on eel health status. The database represents now the first comprehensive pan-European compilation of eel health data, including data from over 10,000 eels from approximately 1,200 sites over 14 countries. Preliminary work has indicated a number of shortcomings and future developments will be needed. Guaranteeing further development of the database, harmonisation of methods, quality assurance, and setting up harmonised eel monitoring strategies over Europe will be a great challenge and will need pan-European cooperative work.

PCBs in wild mussels (Mytilus galloprovincialis) from the N-NW Spanish coast: current levels and long-term trends during the period 1991-2009

Concentrations of polychlorinated biphenyls (PCBs) were determined in wild mussels (Mytilus galloprovincialis) from seven areas of the N-NW Spanish coast, during the period 1991-2009. The studied area is comprised of highly productive ecosystems which support important commercial fishing and shellfishing activities. The seven PCBs indicator congeners recommended by ICES (IUPAC nos. 28, 52, 101, 118, 138, 153 and 180), were analysed by gas chromatography with an electron capture detector (GC-ECD). Lowest average concentrations of PCBs were recorded in Arousa (1.04 μg kg(-1) wet weight), a low populated area with no industry; while the highest levels were found in areas near cities and/or showing a high industrial activity such as: Bilbao Ziérbena (139 μg kg(-1) ww) or A Coruña (55 μg kg(-1) ww). The hexachlorinated congeners CB153 and CB138 dominated the profiles in all wild mussel populations, although a geographical pattern was found in which the relative contributions of the lower chlorinated congeners were higher in the west coast (Rías of Vigo, Pontevedra and Arousa), which may reflect the occurrence of recent inputs of those compounds in the area. Finally, the application of the Mann-Kendall's test demonstrate the existence of a significant decrease in PCBs levels since 1991 up to 1996 in the studied area, whereas either a slow decrease or stable concentrations were registered over the past decade.

Organochlorines and heavy metals in wild caught food as a potential human health risk to the indigenous Māori population of South Canterbury, New Zealand

Increasing concentrations of anthropogenic contaminants in wild kai (food) of cultural, recreational and economic importance to the indigenous Māori of New Zealand is a potential human health risk. Contaminants that are known to bioaccumulate through the food chain (e.g., organochlorine pesticides (OCPs), PCBs and selected heavy metals) were analysed in important kai species including eel (Anguilla sp.), brown trout (Salmo trutta), black flounder (Rhombosolea retiaria) and watercress (Nasturtium officinale) from important harvesting sites in the region of South Canterbury. Eels contained relatively high wet weight concentrations of p,p'-DDE (8.6-287ng/g), PCBs ((32)Σ(PCB); 0.53-58.3ng/g), dieldrin (<0.05-16.3ng/g) and Σchlordanes (0.03-10.6ng/g). Trout and flounder contained lower concentrations of organochlorines than eels, with p,p'-DDE wet weight concentrations ranging from 2.2 to 18.5ng/g for trout and 6.4 to 27.8ng/g for flounder. Total arsenic wet weight concentrations were below detection limits for eels but ranged from 0.27 to 0.89μg/g for trout and 0.12 to 0.56μg/g for flounder. Mercury concentrations ranged from 0.02 to 0.56μg/g, 0.11 to 0.50μg/g and 0.04 to 0.10μg/g (ww) for eel, trout and flounder respectively. Lifetime excess cancer risk was calculated through established risk assessment procedures, highlighting dieldrin, ΣPCBs and p,p'-DDE in eels and arsenic in trout and flounder as primary contaminants of concern. A second non-cancer chronic health risk assessment indicated that mercury and PCBs were a potential concern in eels and mercury in trout. A cumulative lifetime cancer risk assessment showed potential health risk for consumption of some species, even at low consumption rates and provided the basis for establishing recommended dietary consumption limits for harvest sites within the study region.