Monitoring of organic pollutants in marine environment by semipermeable membrane devices and mussels: accumulation and biochemical responses

The cerium oxide nanoparticles toxicity induced physiological, histological and biochemical alterations in freshwater mussels, Unio crassus

INTRODUCTION

Releasing of cerium oxide nanoparticles (nano-CeO2) to the nature has increased due to the widespread use in many fields ranging from cosmetics to the food industry. Therefore, nano-CeO2 has been included in the Organization for Economic Co-operation and Development's (OECD) priority list for engineering nanomaterials. In this study, the effects of nano-CeO2 on the freshwater mussels were investigated to reveal the impact on the freshwater systems on model organism.

METHODS

First, the chemical and structural properties of nano-CeO2 were characterized in details. Second, the freshwater mussels were exposed to environmentally relevant concentrations of nano-CeO2 as 10 mg, 25 mg and 50 mg/L during 48-h and 7-d. Third, after the exposure periods, hemolymph and tissue samples were taken to analyse the Total Hemocyte Counts (THCs) histology and oxidative stress parameters (total antioxidant status, glutathione, glutathione-S-transferase, and advanced oxidative protein products).

RESULTS

Significant decrease of the THCs was observed in the nano-CeO2 exposed mussels compared to the control group (P < 0.05). The histological results showed a positive association between nano-CeO2 exposure concentration in the water and level of tissue damage and histopathological alterations were detected in the gill and the digestive gland tissues. Oxidative stress parameters were slightly affected after exposure to nano-CeO2 (P > 0.05). In conclusion, this study showed that acute exposure of freshwater mussels to nano-CeO2 did not pose significant biological risk. However, it has been proven that mussels are able to accumulate nano-CeO2 significantly in their bodies.

CONCLUSION

This suggests that nano-CeO2 may be a potential risk to other organisms in the ecosystem through trophic transfer in the food-web based on their habitat and niche in the ecosystem.

Bioaccumulation of PAHs in marine bivalves of the Santos Estuary (Brazil) associated with the evaluation of human consumption

The present study aimed to evaluate concentrations of 16 priority PAHs in the mussel Perna perna and oyster Crassostrea rhizophorae of the Santos Estuary (Brazil) and the potential risk to human health associated with the consumption of these species. The levels of ΣPAHs in the tissues of bivalves ranged from 96.94 to 988.76 μg/kg for mussels and from 88.38 to 138.62 μg/kg for oysters. A general trend of higher concentrations of PAHs was observed according to the increase in log Kow values in both species. The estimated amount of ΣPAHs via mussel and oyster intake ranged from 1.0 to 3.2 ng/kg and from 0.4 to 1.2 ng/kg of body weight per day, respectively. The calculated THQs, HI and CRs for the regular consumption of raw bivalves followed the internationally acceptable limits and represent a low risk to human health.

Metal levels in sediments and caged mussels in one of the industrial zones of the Eastern Aegean Sea

Caged mussels make biomonitoring studies possible with their ability to take up pollutants in the industrial zones. The goal of this study was applied to assess metal levels in the biomonitoring organism Mytillus galloprovincialis Lamark, 1819 for transplantation from three locations for two periods (2016-2018) in the industrial zone of the Eastern Aegean Sea. Metals were also determined in sediments; high concentrations of Hg, As and Zn in surficial sediments of Nemrut Bay can cause hazardous impacts on the aquatic environment with respect to sediment quality guidelines. The highest contamination factor (Cf) was calculated for Hg (Cf = 10), suggesting serious anthropogenic pollution in the study area. According to Pearson product-moment correlation analysis, As is not correlated with other metals due to As mainly originating from natural sources. Hg, Cd, Pb and Cu concentrations increased in the transplanted mussels during a field transplant experiment because of chronic pollution from industrial activities. Cumulative effects of both the oil refinery and shipbreaking industry cause higher uptake of Hg, Cd, Pb and Cu in sampling station 3 as a result of higher exposure levels in transplanted mussels. Mussel consumption was compared with provisional maximum tolerable intake from literature; the estimated provisional intake (EDI) for Cd, Hg and Pb does not exceed maximum levels; however, Cu and Zn exceed reference EDI values. Since Nemrut Bay is heavily influenced by industrialisation, it is not a suitable region for seafood production.

Bioaccumulation and toxicokinetics of polycyclic aromatic compounds and metals in giant floater mussels (Pyganodon grandis) exposed to a simulated diluted bitumen spill

Oil spills constitute a major risk to the environment and the bioaccumulation potential of the derived oil constituents will influence their impact on aquatic biota. Here we determined the bioaccumulation potential and toxicokinetic parameters of polycyclic aromatic compounds (PACs) and various selected metals in the giant floater mussels (Pyganodon grandis) following experimental oil spills in a freshwater lake. Specifically, these mussels were exposed ex situ for 25 days to water contaminated with naturally weathered diluted bitumen (dilbit), a form of oil commonly transported through pipelines. We detected greater concentrations of total PAC in mussels (∑PAC₄₄) exposed to dilbit-contaminated water (25.92-27.79 μg g^-1 lipid, n = 9, at day 25 of the uptake phase) compared to mussels from a control with no exposure to dilbit (average of 2.62 ± 1.95 μg g^-1 lipid; ±SD, n = 17). This study demonstrates the importance of including alkylated PACs when assessing the impacts of an oil spill as the concentration of alkylated PACs in mussel tissue were an order of magnitude higher than their parent counterparts. However, metal accumulation in dilbit-exposed mussels did not exceed the unexposed controls, suggesting no excess metal accumulation by mussels from a 25-day dilbit exposure. From first-order one-compartment models, mean uptake rate constants (0.78-18.11 L g^-1 day^-1, n = 29) and bioconcentration factors (log values from 4.02 to 5.92 L kg^-1, n = 87) for the 29 individual PACs that accumulated in mussels demonstrated that some alkylated PACs had greater bioaccumulation potential compared to their parent PAC counterpart but for the most part, alkylated and parent PACs had comparable BCF values. Results from this study also demonstrated that giant floater mussels could be used to biomonitor PAC contamination following oil spills as PACs accumulated in mussel tissue and some were still detectable following the 16-day depuration phase. This study provides the largest, most comprehensive set of toxicokinetic and bioaccumulation parameters for PACs and their alkylated counterparts (44 analytes) in freshwater mussels obtained to date.

Exploring the influence of concentration fluctuation and matrix effects on a passive sampler of triolein-embedded cellulose acetate membrane measuring polychlorinated biphenyls in water

A membrane of triolein-embedded cellulose acetate membrane (TECAM), as an integrative passive sampler, was applied to adsorb 28 polychlorinated biphenyls (PCBs) from pure water and sea water in order to probe into the influence of concentration fluctuation and water matrix. The results demonstrated the temporal variations of PCBs concentrations in TECAM followed the first-order kinetics model. The periodic refreshment of solution and matrix effects of sea water significantly prolonged the time that PCBs reached equilibrium stage. The refreshment facilitated the uptake mass in TECAM. On the contrary, the matrix effects of sea water and dissolved organic matter (DOM) declined the PCBs absorption to TECAM. The average logK_P values of PCBs in pure water were about 1.2 log unit higher than those in sea water in the experiments that the solution was not refreshed, while the difference of average logK_P values narrowed to 0.3 log unit if the PCBs solutions were periodically refreshed. The correlation between logK_P and logK_OW values fitted the quadratic curve well, which was similar to semi-permeable membrane device (SPMD). The appropriate sampling times (t_94%) ranged from 98.8 to 819 h (mean 500 h) for pure water with refreshment, much longer than those in sea water with refreshment (80.1~410 h, mean 189 h). The t_94% values in the solution with high DOM content increased significantly, up to 409 h. Furthermore,  comparing the two experiments that the spiked pure water and sea water solution were refreshed frequently, the estimated sampling rates (R_s) in pure water (0.154~2.06 L/day with a mean value of 0.605 L/day) were slightly lower than those in sea water (0.292~3.84 L/day with a mean value of 1.69 L/day). However, the R_s values in sea water with DOM declined sharply to 0.042 L/day. Therefore, concentration fluctuation, matrix effect, and DOM contents of sea water evidently posed significant influence on dynamic parameters of TECAM absorption, which would be screened and probed detailed in future.

Polychlorinated biphenyls and organochlorine pesticides in breast milk samples and their correlation with dietary and reproductive factors in lactating mothers in Istanbul

Persistent organic pollutants (POPs) continue to threaten the environment and human health. We have investigated levels of polychlorinated biphenyls (PCBs) and organochlorinated pesticides (OCPs) in breast milk samples. A questionnaire was also obtained from the study participants. A total of 48 healthy lactating mothers (mean age: 29.5±0.8 years) living in Istanbul volunteered to participate in this study. High-resolution analyses of several OCPs and PCB congeners were done by gas chromatography. The levels of seven major PCB congeners (28, 52, 101, 118, 138, 153, and 180) and eight OCPs (α-benzenehexachloride, β-benzenehexachloride, δ-benzenehexachloride, hexachlorobenzene (HCB), and 2,4'-dichlorodiphenyldichloroethylene (2,4DDE), 4,4'-dichlorodiphenyldichloroethylene (4,4DDE), 2,4'-dichlorodiphenyltrichloroethane (2,4DDT), and 4,4'-dichlorodiphenyltrichloroethane (4,4DDT)) were determined. The analysis showed that the highest levels of PCBs were observed in PCB 52 (22.99±8.78 ng/g lipid), PCB 101 (12.22±7.8 ng/g lipid), PCB 28 (11.44±5.16 ng/g lipid), and PCB 153 (1.70±0.74 ng/g lipid). The highest OCPs detected were 4,4DDT (3.33±2.05 ng/g lipid) and 4,4DDE (0.86 ± 0.39 ng/g lipid), and the lowest was observed in HCB (0.016 ± 0.01 ng/g lipid). Our findings show that traces of PCBs and OCPs are still present in breast milk of lactating women living in Istanbul, and these pollutants decline in multipara women compared to primipara mothers. We also suggest that breast milk is a useful and representative biological tool for human biomonitoring of POPs.

Monitoring of polycyclic aromatic hydrocarbons in transplanted mussels (Mytilus galloprovincialis) and sediments in the coastal region of Nemrut Bay (Eastern Aegean Sea)

Polycyclic aromatic hydrocarbons (PAHs) were determined in the coastal region of Nemrut Bay, Eastern Aegean. Sediment and caged mussels were evaluated for sixteen PAHs. High contamination was observed in the sediment sampling sites next to the petrochemical refinery. Low molecular weight PAH levels were dominant in the sediments and the ratio LMW/HMW were higher than one, indicating petrogenic origin pollution. The m-ERM-q values of the sediments were classified as high-priority sites near the refinery while other sites were categorized as medium-low sites. 4-ring PAHs were found to be dominant in the mussels. PAHs were originated from petroleum and mixed sources (petrogenic, pyrogenic) both two transplantation experiments. The assessment of human health risk based on the Carcinogenic `Toxic Equivalents suggested that the mussels have high capability to give rise to carcinogenic risks. PAH levels in the mussels were above the Recommended Total Carcinogenic PAH limits set by the European Union.

Mytilidae as model organisms in the marine ecotoxicology of pharmaceuticals - A review

Growing production and consumption of pharmaceuticals is a global problem. Due to insufficient data on the concentration and distribution of pharmaceuticals in the marine environment, there are no appropriate legal regulations concerning their emission. In order to understand all aspects of the fate of pharmaceuticals in the marine environment and their effect on marine biota, it is necessary to find the most appropriate model organism for this purpose. This paper presents an overview of the ecotoxicological studies of pharmaceuticals, regarding the assessment of Mytilidae as suitable organisms for biomonitoring programs and toxicity tests. The use of mussels in the monitoring of pharmaceuticals allows the observation of changes in the concentration and distribution of these compounds. This in turn gives valuable information on the amount of pharmaceutical pollutants released into the environment in different areas. In this context, information necessary for the assessment of risks related to pharmaceuticals in the marine environment are provided based on what effective management procedures can be developed. However, the accumulation capacity of individual Mytilidae species, the bioavailability of pharmaceuticals and their biological effects should be further scrutinized.

The application of molecularly imprinted polymers in passive sampling for selective sampling perfluorooctanesulfonic acid and perfluorooctanoic acid in water environment

Modeling and predicting of a novel polar organic chemical integrative sampler (POCIS) for sampling of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) using molecularly imprinted polymers (MIPs) as receiving phase are presented in this study. Laboratory microcosm experiments were conducted to investigate the uptake kinetics, effects of flow velocity, pH, and dissolved organic matter (DOM), and also the selectivity of the POCIS. In this study, uptake study of PFOA and PFOS sampling on MIP-POCIS, over 14 days, was investigated. Laboratory calibrations of MIP-POCIS yielded sampling rate (R_s) values for PFOA and PFOS were 0.387 and 0.229 L/d, higher than POCIS using commercial sorbent WAX as receiving phase (0.133 and 0.141 L/d for PFOA and PFOS, respectively) in quiescent condition. The R_s values for PFOA and PFOS sampling on MIP-POCIS were increased to 0.591 and 0.281 L/d in stirred condition (0.01 m/s), and no significant increase occurred when the flow velocity was further increased. The R_s values were kept relatively high in the solution of which the pH was lower than the isoelectric point (IEP) of MIP-sorbent and decreased when the solution pH was extend the IEP value. Under the experimental conditions, DOM seemed to slightly facilitate the R_s values of PFOA and PFOS in MIP-POCIS. The results showed that the interaction between the target compounds and the receiving phase was fully integrated by the imprinting effects and also the electrostatic interaction. Finally, comparing the sampling rate of WAX-POCIS and the MIP-POCIS, the MIP-POCIS offers promising perspectives for selective sampling ability for PFOA and PFOS.