Bioaccumulated Concentrations Research Articles

Baseline bio-accumulation concentrations and resulting oxidative stress in Synodontis zambezensis after an acute laboratory exposure to 4,4′-DDT

The use of 1,1′-(2,2,2-Trichloro-1,1-ethanediyl)bis(4-chlorobenzene) (DDT) as a pesticide for the control of insects vectors responsible for the spread of many life threatening diseases was officially banned in 1972 by the United States Environmental Protection Agency (USEPA). It was banned throughout the world, in most developed countries, because of the toxic effects it causes in wildlife, including birds and fish. However, DDT is still used in approximately 43 African countries, including South Africa, to control the spread of malaria. The lipophilic nature of DDT and therefore its persistence in the environment makes it extremely important for laboratory based studies to be conducted in an effort to evaluate the accumulation potential and possible physiological effects of DDT in aquatic organisms under controlled conditions. The aim of this study was to establish baseline bioaccumulation concentrations within Synodontis zambezensis following an acute exposure to 4,4′-DDT. The three metabolites analysed were 4,4′-DDE, 4,4′-DDD and 4,4′-DDT. None of the 2,4′-isomers were analysed in this study since the acute exposure used a solution of 98.7% pure 4,4′-DDT (Sigma-Aldrich PESTANAL®, Analytical Standard, CAS-No 50-29-3, Batch number SZBE057XV) and not a mixture of 4,4′-DDT and 2,4′-DDT as found in technical grade DDT. Soxhlet extraction of tissue samples and liquid/liquid extraction of water samples followed by analysis through Gas-chromatography mass-spectrophotometry was completed. Mean 4,4′-DDE, 4,4′-DDD and 4,4′-DDT concentrations ranged from 15.34 ng/g to 45.34 ng/g, 28.16 ng/g to 63.25 ng/g and 28.64 ng/g to 96.21 ng/g respectively. All of the accumulated concentrations fell within environmentally relevant concentrations with no input through the food web. The accumulated concentrations of 4,4′-DDT and its three metabolites resulted in oxidative stress responses within the gills and the liver tissue of S. zambezensis. Significant differences (p ≤ .05) were observed between malondialdehyde (MDA) and reduced glutathione (GSH) within the liver and in superoxide dismutase (SOD), catalase (CAT) and reduced glutathione (GSH) in the gills.

Identification of the highest potential human health and environmental hazard in contaminated sediment near the point sources in the northwest Persian Gulf

The overall goal of this work was to determine the concentration levels and the potential ecological risks of 30 polycyclic aromatic hydrocarbons in the Persian Gulf sediments, Iran. The study also predicted the bioaccumulation of PAHs using the Monte Carlo simulation. For these goals, 68 surface sediment samples were collected from the Persian Gulf in January 2017. Then, the experiments were performed with Soxhlet system, chromatographic column and GC-MS instrument. According to the Canadian Sediment Quality Guidelines, 35.29% of sampling sites exhibited high potential adverse biological effects and 79.41% of samples have a low probability of toxicity. The mean bioaccumulated concentrations of carcinogenic PAHs in the Persian Gulf were predicted as 207.78 ± 262.23, 116.06 ± 146.47 and 69.26 ± 87.41 ng g–1 for mollusks, shrimps and crabs, respectively. The mean Toxic Equivalency and Mutagenic Equivalent Quotient for sediments was 702.06 ± 1012.37 and 500.37 ± 665.71 ng g−1, respectively. The 95th percentile carcinogenic and non-carcinogenic risks calculated for children and adults were lower than the threshold values of 10−6 and 1.0, respectively, revealing no potential health risk. The highest potential risks for toxicity were observed at sampling sites close to the Nowruz oil field and Mahshahr petrochemical economic zone based on the highest TEQcarc and MEQcarc values in this area.

The tendency of linuron in microcosmic system and its response to hydrodynamic conditions

The environmental fate and bioaccumulation of linuron in a laboratory microcosm were investigated at three flow velocity over a period of 10 days. Linuron concentrations were quantified in the environmental media water, sediment, algae and fish after 1, 2, 4, 7 and 10 days of exposure. The results showed that rapid decrease in water phase of the microcosm was occurred, linuron had decreased to 56.7%-67.9% of the initial concentrations on day 10, and reduction rates showed an obvious increase with increased flow velocity. The linuron concentrations in the sediment were 1.25-2.13 ng/g on day 10, which were much less than that in algae (387-477 ng/g). The linuron was widely detected in fish tissues, and the bioaccumulation concentrations were generally in the following order: liver > kidney > brain > skin > muscle > gill at an early stage of exposure. However, the ability of liver detoxification increased with the exposure time and exposure flow velocity, so that the bioaccumulation potential was highest in kidney at the end stage of exposure. This result indicates that a significant uptake potential of linuron in organisms, further studies are necessary to elucidate food chain bioaccumulation and toxicological effects of linuron.

Heavy Metal Copper (Cu) Distribution in Water and Its Bioaccumulation in Green Mussel (Perna viridis) in Coastal Area of Ujung Pangkah, Gresik District

Environmental pollution in the form of increased concentration of heavy metal Copper (Cu) becomes the main factor that can affect water quality and inhibit green mussel culture ( Perna viridis ) in Ujung Pangkah Coastal Area of Gresik District. The purpose of this research is to analyze concentration of heavy metal Copper (Cu) on water and its bioaccumulation in green mussel ( P. viridis ) in Ujung Pangkah waters, Gresik District. This research will be conducted from June to August 2017. The method used in this research is descriptive method. Sampling of seawater and mussel by purposive sampling. Cu heavy metal content in Ujung Pangkah waters, Gresik District has 0.003 – 0.006 ppm in July and 0.002 – 0.006 ppm in August. That value is still safe below predetermined quality standards. The results of heavy metal measurement test in shellfish has 0.159 to 0.69 ppm in July and 0.162 – 0.71 ppm in August. The high concentrations of Cu heavy metals in Ujung Pangkah waters are simultaneous to the bioaccumulation concentration in the green mussel. The higher concentration in the waters, the higher the bioaccumulation in the green mussels. And vice versa. The distribution of Cu heavy metal concentration at point 4 is the highest. While at point 1 has the lowest Cu heavy metal concentration. Keywords: Copper, Bioaccumulation, Green Mussel, Heavy Metal, Perna viridis .

Bioaccumulation and effects of dietary exposure to the alternative flame retardant, bis(2-ethylhexyl) tetrabromophthalate (TBPH), in the Atlantic killifish, Fundulus heteroclitus.

Bis(2-ethylhexyl) tetrabromophthalate (TBPH), a high production volume flame retardant chemical used as a replacement for banned flame retardants, has been detected in media and human and wildlife tissues globally. We describe bioaccumulation and biological effects from dietary exposure of TBPH to an estuarine fish, Atlantic killifish, Fundulus heteroclitus. Briefly, adult fish were fed carrier control or chemically amended diets for 28 d, followed by 14 d of control diet feeding. Diets were amended with TBPH (TBPH_LO diet, 139 μg/g dry wt, or TBPH_HI diet, 4360 μg/g dry wt) or a polychlorinated biphenyl congener (PCB153 diet, 13 μg/g dry wt), which was included as a positive control for bioaccumulation. Although bioaccumulation of either chemical correlated with fish size, only a small proportion of the TBPH offered (<0.5% total TBPH) had bioaccumulated into TBPH-treated fish by 28 d. In contrast, 24.5% of the PCB153 offered was accounted for in 28-d PCB-treated fish. Although 28-d bioaccumulated concentrations of TBPH differed by sex and treatment, sexes did not differ in their rates of TBPH bioaccumulation, and the time to achieve 50% of 28 d concentration (T1/2 ) was estimated to be 13 d. Depuration rates of TBPH did not differ by sex or treatment, and the time after exposure to achieve T1/2 was estimated to be 22 d. Independent of treatment, male fish grew faster than female fish, but for both sexes reproductive condition (gonadal somatic index) declined unexpectedly over the experimental period. Across treatments, only the TBPH_LO treatment affected growth, reducing male but increasing female growth rates by small amounts relative to respective controls. In summary, our study used very high concentrations of dietary TBPH to contaminate fish tissues above the highest levels reported to date in wild biota, yet we observed few adverse biological effects. Environ Toxicol Chem 2018;37:2350-2360. © 2018 SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Retention and characteristics of microplastics in natural zooplankton taxa from the East China Sea

The ubiquitous presence and persistence of microplastics (MPs) in aquatic environments have become of particular concern in recent years. Biological interactions are among the key processes that affect the impact and fate of MPs in the oceans. Zooplankton is one of the most sensitive taxa because their prey is approximately the same size as MPs. However, the status of MPs in zooplankton within natural marine environments remains largely unknown. By focusing on zooplankton in the East China Sea, the characteristics, bioaccumulated concentration, and retention of MPs for 10 zooplankton groups were systematically studied. Three types of MPs were found in zooplankton: fibres, pellets, and fragments. The fibres (54.6%) were more common than the other two types. The average lengths of the fibres, pellets, and fragments were 295.2 ± 348.6 μm, 20.3 ± 11.0 μm, and 82.4 ± 80.5 μm, respectively. Nineteen polymers were detected in the zooplankton via the Thermo Scientific Nicolet iN10 Infrared Microscope. Polymerized oxidized organic material and polyester were dominant, accounting for 35.9% and 25.6% of the polymers, respectively. The bioaccumulated concentration of MPs in the 10 zooplankton taxa varied from 0.13 pieces/zooplankton for Copepoda to 0.35 pieces/zooplankton for Pteropoda. The bioaccumulated concentration was negatively correlated with the abundance of zooplankton, showing a significant biological dilution effect. The bioaccumulated concentration was also influenced by the feeding mode of zooplankton, showing a trend of omnivorous > carnivorous > herbivorous. High retention of MPs was found in the zooplankton community of the East China Sea, achieving 19.7 ± 22.4 pieces/m3. This is much higher than the MP retention in zooplankton from other reported sea areas. By revealing the characteristics and retention of MPs in the natural zooplankton taxa from the East China Sea, this research identified the influence that MPs have on zooplankton in a typical coastal environment. This information can be utilized for subsequent controlled experiments and risk assessments.

Longitudinal survey of lead, cadmium, and copper in seagrass Syringodium filiforme from a former bombing range (Vieques, Puerto Rico).

Trace element composition in plant biomass could be used as an indicator of environmental stress, management practices and restoration success. A longitudinal study was conducted to compare Pb, Cd, and Cu content in seagrass Syringodium filiforme collected at a former bombing range in Puerto Rico with those of a Biosphere Reserve under similar geoclimatic conditions. Trace elements were measured by atomic absorption after dry-ashing of samples and extraction with acid. In general, levels of Pb, Cd, and Cu varied during 2001, 2003, 2005-2006, and 2013-2016. Results showed that bioaccumulated concentration of these trace elements were consistently higher, but not significant, at the bombing range site. As expected in polluted areas, greater variability in Pb and Cd content were observed in the military impacted site with levels up to 14 and 17 times higher than seagrass from the reference site, respectively. Although a decrease in Pb was observed after cessation of all military activities in 2003, the concentration in plant biomass was still above levels of ecological concern, indicating that natural attenuation is insufficient for cleanup of the site.

Caged Gammarus as biomonitors identifying thresholds of toxic metal bioavailability that affect gammarid densities at the French national scale

Bioaccumulated concentrations of toxic elements in biomonitor invertebrate species have already been used to successfully link metal bioavailability and impairments of stream macroinvertebrate communities at the scale of the watershed. However, implementing this empirical comparative approach at a greater spatial scale remains a challenge due to the diversity of biogeographical contexts encompassed by regional and national scales. We showed in previous studies that the use of standard organisms caged permits the use of a common biomonitor over a far greater geographical range, while limiting the influence of confounding factors on levels of bioavailable contamination. In this study, levels of Cd, Hg, Ni and Pb contamination assessed by active biomonitoring with caged Gammarus fossarum were compared to abundances of on-site gammarids on 94 sites in France. Based on this national dataset of in situ bioassays, we first re-determined bioavailable background assessment concentrations (BBACs), i.e. concentrations measured in caged G. fossarum indicating a significant bioavailable contamination, which we had previously defined at a regional scale for these four metallic elements. On-site gammarid abundances were retrieved from monitoring programs implemented by French water agencies for the evaluation of ecological status for the European Water Framework Directive. These abundances were corrected for the influence of stream physico-chemical typology in order to permit a reliable comparison of gammarid densities between sites at the national scale. Clear trends of degradation of gammarid densities with increasing levels of bioaccumulated concentrations were identified for three of the four elements (Cd, Ni and Pb). Threshold concentrations in caged organisms above which the numbers of free-ranging gammarids were abnormally low – namely bioavailable ecological assessment concentrations (BEACs) – were determined. The reliability and validity of the BEACs, their comparison with BBACs and their usefulness in terms of prioritisation of contaminants, sites in freshwater management, are discussed.

Enantioselective Bioaccumulation, Tissue Distribution, and Toxic Effects of Myclobutanil Enantiomers in Pelophylax nigromaculatus Tadpole.

Research on the enantioselective behavior of chiral pesticides on amphibians has received growing attention, because amphibians are experiencing a population decline and amphibian metamorphosis shares many similarities with human fetal development. In this study, the enantioselective behavior of myclobutanil on Pelophylax nigromaculatus tadpole was studied. The antioxidant enzyme (SOD, GST) activities and malondialdehyde (MDA) content were investigated to assess the different toxic effects when tadpoles were exposed to myclobutanil enantiomers for 96 h. In the chronic exposure experiment, the bioaccumulation concentration of (-)-myclobutanil in tadpoles is significantly higher than that of (+)-myclobutanil, and the concentration of myclobutanil in tadpole intestine and liver was higher compared with other tissues. During the elimination experiment, about 95% of myclobutanil in tadpoles was eliminated within only 24 h. On the basis of these data, the enantiomeric differences should be taken into consideration in the risk assessment of myclobutanil.

The mismatch of bioaccumulated trace metals (Cu, Pb and Zn) in field and transplanted oysters (Saccostrea glomerata) to ambient surficial sediments and suspended particulate matter in a highly urbanised estuary (Sydney estuary, Australia).

A significant correlation between sedimentary metals, particularly the 'bio-available' fraction, and bioaccumulated metal concentrations in the native Sydney rock oyster (Saccostrea glomerata) tissues has been successfully demonstrated previously for Cu and Zn in a number of estuaries in New South Wales, Australia. However, this relationship has been difficult to establish in a highly modified estuary (Sydney estuary, Australia) where metal contamination is of greatest concern and where a significant relationship would be most useful for environmental monitoring. The use of the Sydney rock oyster as a biomonitoring tool for metal contamination was assessed in the present study by investigating relationships between metals attached to sediments and suspended particulate matter (SPM) to bioaccumulated concentrations in oyster tissues. Surficial sediments (both total and fine-fraction), SPM and wild oysters were collected over 3years from three embayments (Chowder Bay, Mosman Bay and Iron Cove) with each embayment representing a different physiographic region of Sydney estuary. In addition, a transplant experiment of farmed oysters was conducted in the same embayments for 3months. No relationship was observed between sediments or SPM metals (Cu, Pb and Zn) to tissue of wild oysters; however, significant relationship was observed against transplanted oysters. The mismatch between wild and farmed, transplanted oysters is perplexing and indicates that wild oysters are unsuitable to be used as a biomonitoring tool due to the involvement of unknown complex factors while transplanted oysters hold strong potential.

Naturally floating microalgal mat for in situ bioremediation and potential for biofuel production

The objective of this study is to understand the fatty acid composition of a naturally floating microalgal mat with respect to seasonal variations in the water of a eutrophic lagoon on the west coast of India. The floating microalgal mat was explored for its bioaccumulation of metals and lipids for sustainable utilization in biofuel production. The effects of the nutrient profile and heavy metals in the water on the community composition of microalgal mat in different seasons were also studied and a principal component analysis was performed. It was observed that the unsaturated fatty acids such as C18:1n9c and C18:2n6c increased in low temperatures. The reverse effect was observed during the pre-monsoon season with augmented C16:0 fatty acid and an overall increment in saturated fatty acids. The Cyanophyceae and diatom community nurtured the growth during the pre-monsoon season by acquiring a higher bioaccumulation concentration factor (BCF) for Mn (3812.6±680), As (90.47±15.38), Ni (1620±163.64), Cr (73.27±21.23), and Cu (46.40±11.44). The higher abundance of Cyanophyceae in the microalgal mat exhibited better metal endurance during the pre-monsoon season, which could be obviously tilized for the bioremediation of heavy metals. The biodiesel prepared from the microalgal mat met European biodiesel standards.

The aeration effect in pilot reed bed to phytoremediate water containing Lead (Pb)

A pilot reed bed study was conducted with the aid of aeration to remove lead (Pb) contaminated water using Scirpus grossus L. f. The plants were grown in sand medium in pilot-scale reed beds, and exposed to water containing Pb in a various concentration (10, 30 and 50 mg/L) with aeration rate of 2 L/min. The samples were taken on day-1, day-14, day-28, day-42, day-70 and day-98. The results showed that Pb concentration in water decreased 74% on day-7, 80% on day-14, 99% on day-28 and reach 100% on day-48 for treatment 10 mg/L. Pb concentration decreased 91% on day-7, 93% on day-14 and then on the day-28 the reduction reached 99% for treatment of 30 mg/L. For Pb treatment of 50 mg/L, the reduction reached 92% on day-7, 96% on day-14, and 99% on day-28. The sand adsorbed Pb up to 7.91×10 -4 mg/kg for 10 mg/L, 1.07×10 -3 mg/kg for 30 mg/L and 2.41×10 -3 mg/kg for 50 mg/L. Pb uptake by plant was 2286 mg/kg on day-98, 4174 mg/L on day-28 and 8297 mg/kg on day-14 for 10, 30 and 50 mg/L, respectively. The highest Bioaccumulation Concentration (BC) was 10618 for 10 mg/L on day-28, 81311 for 30 mg/L and 81467 for 50 mg/L both on day-42, with the Translocation Factor (TF) related to the same day of these BC were 0.13, 0.24, and 0.35 respectively. The highest TF value for 10 mg/L were 0.7 on day-98, 0.38 for 30 mg/L on day-70 and 0.59 for 50 mg/L on day-14.

Potential of Lemna gibba L. and Lemna minor L. for accumulation of Boron from secondary effluents

Aquatic plants are quite effective in removal of pollutants which cannot be removed in secondary treatment. Lemna gibba L. and Lemna minor L. among the aquatic plants were investigated for the removal of boron from the secondary waste water. Differences in Boron uptake were seen in the chosen aquatic macrophytes. Although boron is at low concentration in water, the bioaccumulated concentrations in Lemna minor L. and Lemna gibba L. were at high levels of between 140 mg Bg 140 –1and 274 mgB g−1, and 381 mgB g−1 523 mgB g−1 respectively. From these results, it was understood that Lemna gibba L. is more prone to accumulate boron compared to Lemna minor L.

Bioaccumulation of metals in Tilapia zillii from Badeni Dam, Côte d'Ivoire

Given the importance of fish as a source of protein and the potential for exposure of humans to metal elements, metal bioaccumulation concentrations in Tilapia zillii from four sites in the Badeni Dam on the Badeni River, Côte d'Ivoire, were analysed in March 2013. There were no significant differences between sites and therefore mean values for the impoundment as a whole were used to compare data with those from the literature. Comparative analysis showed elevated levels of manganese, iron, zinc, copper and cadmium from fish in this study. Due to the absence of human influence in the catchment area, these elevated levels are attributed to the unique geological characteristics of the catchment, compounded by the impoundment conditions. Further studies on fish condition to ascertain the effects of the elevated metal concentrations are recommended.

Simultaneous copper bioaccumulation, growth and lipase production of Rhizopus delemar in molasses medium: optimisation of environmental conditions using RSM

In this study, the bioaccumulation of Cu(II) ions by R. delemar and their influence on growth of the microorganism were assessed, and the impact of Cu(II) ions on the activity of lipase enzyme degradation of lipids in wastewaters by enzymatic hydrolysis was received for consideration. Optimisation of Cu(II) bioaccumulation process was performed by varying three independent parameters (pH, temperature and Cu(II) concentration) using a central composite design (CCD) under response surface methodology (RSM). For the maximum Cu(II) bioaccumulation and lipase production at a desired level of the biomass concentration level, a total of 20 experimental runs were set and the experimental data fitted to the empirical second-order polynomial models. The adequacies of the predicted models for the Cu(II) bioaccumulation, lipase activity and biomass concentration were confirmed by the coefficients of multiple regression (R2), which were adjusted to be 99.6%, 94.5%, 93.4%, respectively indicating reasonably good models for practical implementation. A maximum Cu(II) bioaccumulation of 36.81 mg/L was obtained at pH 6.0, at 32.6°C, and at 50 mg/L initial Cu(II) concentration. The lipase activity of R. delemar decreased only from 505 U/L in Cu(II)-free fermentation medium to 476 U/L in the presence of Cu(II) giving 5.74% decrease in lipase activity.

Toxicity and Bioaccumulation of Petroleum Mixtures with Alkyl PAHs in Earthworms

ABSTRACT The toxicities of three oil products with boiling-point ranges representative of petroleum hydrocarbons were tested on earthworms (Eisenia fetida) to investigate the correlation between bioaccumulated concentrations of polycyclic aromatic hydrocarbons (PAHs) and toxicity. The toxicities to earthworms were in the sequence: kerosene > diesel > bunker-C. After 14 days, the LC50s of the soils contaminated with kerosene, diesel, and bunker-C were 1079, 9135, and 15,609 mg/kg, respectively. Analysis of the body residue concentrations of PAHs in the earthworms showed that the accumulation of alkyl PAHs predominated that of the 16 priority PAHs. Principal component analysis (PCA) identified 12 PAHs, including four alkylated naphthalenes, as the oil constituents that affected mortality in the kerosene-contaminated soil. For the diesel-contaminated soil, eight PAHs were identified, including dibenzothiophene. It was not clear which compounds affected mortality in the bunker-C soil. Across the three series, biota-to-soil accumulation factors (BSAFs) ranged from 10–2.05 to 103.98, and generally increased as the hydrophobicity (Kow) or molecular weight of the alkyl PAHs increased. The toxicity endpoints of each oil product can be used as reference values in the risk assessment of soils contaminated with petroleum, and individual PAHs screened out have implications for future toxicity assessment of petroleum hydrocarbons.

Assessing metal bioaccumulation from estuarine sediments: comparative experimental results for the polychaete Arenicola marina

The purpose of this paper is to compare three approaches for providing information on the bioaccumulation potential of metals from contaminated sediments to the deposit-feeding polychaete Arenicola marina. We present metal (Ag, As, Cd, Cu, Pb and Zn) bioaccumulation results from field-collected sediments quantified through direct measurements of bioaccumulated concentrations in A. marina over a period of 30 days under controlled laboratory exposures and compare these results with bioaccumulated metal concentrations in field-collected organisms from the same sites of collection of the sediments used in the laboratory exposures. For the metals for which model parameters are available (Ag, As, Cd and Zn), we also compare these results with biodynamic model predictions. We considered three UK estuaries characterised by a well-reported history of trace metal contamination and bioavailability in addition to the (control) site of collection of the worms. The results from laboratory-exposed organisms showed that the standard 28-day exposure duration may be adequate to identify the potential for metal bioaccumulation in this polychaete at the sites considered here. However, the time course of bioaccumulated concentrations and the comparison with measured concentrations in field-collected worms show that a steady state has not been reached, confirming the need for extended exposure periods. The worms showed symptoms of stress in feeding and growth during the initial 10 days of exposure and subsequent partial recovery during the following 20 days, suggesting that stress was not always caused by sediment contamination but that it was likely associated with handling and acclimation. At this last stage of the exposure, a generalised biodynamic model was used to provide estimates of bioaccumulated metal concentrations and net accumulation rates in worms. The results of this study highlight the number of factors that should be considered for the interpretation of bioaccumulated metal concentrations in A. marina under laboratory exposures for contaminated sediment assessment, factors that appear to be common to most deposit-feeding polychaetes. A general biodynamic model proved to be a cost-effective method for an initial estimation of the extent and pattern of metal bioaccumulation under specified exposure conditions.

Birnessite와 Hydroxyapatite에 의한 납과 카드뮴 오염퇴적토의 독성저감 평가

The success of stabilization treatment in heavy metal contaminated sediment depends on the heavy metal bioavailability reduction through the sequestration of the heavy metals. This study was performed to assess the changes in the bioavailability of Pb or Cd in the Pb or Cd contaminated sediments by using birnessite and hydroxyapatite as stabilizing agents. The toxicity tests were carried out using a microorganism (Vibrio fischeri), an amphipod (Hyalella azteca) and an earthworm (Eisenia foetida). With Vibrio fischeri, the toxicities of both Pb and Cd were reduced by more than ten times in the presence of birnessite and hydroxyapatite compared to that of in the absence of birnessite and hydroxyapatite. The concentrations of Pb and Cd in the contaminated sediments were lethal to Hyalella azteca, however, in the presence of birnessite and hydroxyapatite more than 90%, on average, of Hyalella azteca survived. With Eisenia foetida, the bioaccumulated concentrations of both Pb and Cd were reduced by more than 75%, on average, lower with the addition of birnessite and hydroxyapatite to the contaminated sediments. These results show that the addition of birnessite and hydroxyapatite can reduce the bioavailability of Pb and Cd in contaminated sediments. In addition, the in situ and ex situ performance of birnessite and hydroxyapatite as stabilizing agents can be verified using the toxicity tests with Hyalella azteca and Eisenia foetida, respectively.

Bioaccumulation of metals (Cd, Cu, Zn) by the marine bivalves M. galloprovincialis, P. radiata, V. verrucosa and C. chione in Mediterranean coastal microenvironments: association with metal bioavailability

The concentrations of Cd, Cu and Zn in both the whole soft tissue and separate organs (gills, mantle, muscle and digestive gland) of wild bivalves (Mytilus galloprovincialis, Pinctada radiata, Venus verrucosa and Callista chione) from three different coastal microenvironments of Greece were monitored from 2003 to 2004. In parallel, by employing appropriate analytical protocols for metal partitioning, the labile fraction of the metals was determined in the dissolved phase, suspended particulate matter and sediments. Differences in the metal levels were detected both among the study areas as well as among the bivalves examined. Significant bioaccumulation was demonstrated regarding Zn in M. galloprovincialis specimens from the highly industrialized Gulf of Elefsis and Cd in P. radiata and V. verrucosa from the Maliakos Gulf, which is influenced by extended agricultural activity occurring at the neighbouring area and a river outflow. Data of the metal levels in the various environmental phases were correlated with their concentrations in bivalves' tissues. The clear relationships obtained in many cases among the labile metal concentrations and the bioaccumulated concentrations in bivalves point out that the labile fraction of a metal is the most bioavailable. The lack of positive correlation for C. chione confirms the occurrence of effective mechanisms of internal regulation of metal concentrations.

Identifying semi-volatile contaminants in fish from Niyang River, Tibetan Plateau

This study investigated the contamination levels and profiles of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), organochlorine pesticides (OCPs) including dichlorodiphenyltrichloroethane and its metabolites (DDTs), hexachlorocyclohexanes (HCHs) and hexachlorobenzene (HCB) in fish from the Niyang River, Tibetan Plateau. The total concentrations of ∑PCB, ∑PBDE and ∑OCP were in the range of 0.246–1.056 ng/g (mean 0.540 ± 0.289 ng/g), 0.280–2.220 ng/g (mean 0.914 ± 0.643 ng/g) and 7.24–13.80 ng/g (mean 10.70 ± 2.31 ng/g), respectively. The total mercury concentration (HgT) in fish ranged from 85 to 217 ng/g dw with an average of 129 ng/g dw, and the concentrations of methyl mercury (MeHg) ranged from 61 to 160 ng/g dw with an average of 102 ng/g dw. The proportion of MeHg contributed to 66–91 % (average 80 %) of HgT for all samples, indicating that organic mercury was the predominant form of mercury in fish muscle. The results revealed that the fish from the Niyang River were contaminated with various persistent toxic pollutants and the potential influencing factors on the bioaccumulation concentration in fish were analyzed using Pearson’s correlation analysis.