Global assessment of arsenic pollution using sperm whales (Physeter macrocephalus) as an emerging aquatic model organism

Interface adsorption characteristics of microplastics on multiple morphological arsenic compounds

Polystyrene (PS) and polyethylene terephthalate (PET) are commonly used materials that degrade into microplastics in the environment. These microplastics, possessing unique physical properties, can adsorb pollutants and contribute to composite pollution effects. This study examined the loading characteristics and toxic effects of PS and PET on six arsenic compounds, revealing that PS and PET displayed different adsorption capacities for these compounds, with PS demonstrating high adsorption for monomethylarsonic acid (MMA). The adsorption kinetics and isotherm analyses indicated that arsenic compounds quickly reached equilibrium on PS and PET. The kinetics were effectively described by pseudo-first-order models, and the isotherms aligned with the Langmuir and Freundlich models. Furthermore, simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) were used to desorb arsenic compounds bound to PS and PET. The effects of aging, pH, salinity, anions, and humic acid (HA) on the ability of inorganic arsenic (iAs) to bind to PS and PET were analyzed. The results indicated that aging and HA increased the adsorption capacity of the microplastics, while salinity, anions, and elevated pH negatively affected this capacity. Additionally, the influence of microplastics and iAs on the clearance of free radicals by reduced glutathione (GSH) was explored. Microplastics inhibited the clearance of 1,1-diphenyl-2-picryl-hydrazyl (DPPH) by GSH, whereas iAs, especially arsenate, facilitated this process, likely due to synergistic effects with the oxidized form of GSH generated through GSH reactions. This study offers a theoretical foundation for understanding how microplastics transport various forms of arsenic compounds and their potential environmental risks.

Seasonal Monitoring of Heavy Metal Pollution in Water and Zebra Mussels Dreissena polymorpha as a Potential Bioindicator Species from Lake Habitat

In aquatic ecosystem, metal pollution is an important environmental hazard. Mussels as a bioindicator species are often used for assessment the presence of potentially toxic metals. Hence, the present study aimed to assess the effect of seasonal variations on some heavy metals (Cd, Cr, Pb, As, Zn and Cu) accumulation in water and Dreissena polymorpha from lake habitat. Our result indicated that Zn accumulated at a very high level in the zebra mussels while As accumulated at a high level in water samples. Seasonal variations significantly affected Cu concentration in the water samples (P < 0.05) while Cr concentration in the mussel samples was significantly affected by seasonal variations (P < 0.05). According to the water analysis, mean concentrations of metals are below the maximum limits established by the World Health Organization and USEPA, except As. Overall, our data emphasize anthropogenic pollution in the Turkish aquatic environment and confirm the use of D. polymorpha as a prospective biomonitor for metal polluted sites'.

Ascorbic acid ameliorated the sperm quality of rainbow trout (Oncorhynchus mykiss) against arsenic toxicity: Impact on oxidative stress, fertility ability and embryo development

Arsenic (As) is a heavy metal and aquatic pollutant and adversely impacts the reproduction of male fish. As a chain-breaking antioxidant, ascorbic acid (AA) has high water solubility and low toxicity. In this context, the current study was performed to assess the protective role of AA (1 mM) on the sperm cells of the rainbow trout (Oncorhynchus mykiss) exposed to sublethal concentrations of As (8, 16 and 32 mg/L). Sperm quality parameters were analyzed using a sperm class analyzer system. Lipid peroxidation and antioxidant enzyme levels were used as indicators of oxidative stress. The fertilization, eyeing and hatching rates were determined as gamete markers. Reduced sperm quality parameters and fertility capacity resulted from in vitro exposure to As (P < 0.05). The oxidative stress in sperm cells increased after As exposure (P < 0.05). The presence of AA improved sperm movement parameters and fertility potential (P < 0.05). Overall, AA had a positive effect on oxidative stress and fertility ability against As toxicity and AA supplementation ameliorated detrimental effects of As in sperm cells.

Arsenate toxicity to the marine microalga Chlorella vulgaris increases under phosphorus-limited condition

To understand the arsenic (As) toxicity to aquatic organisms in the phosphors-polluted aquatic ecosystem, the growth, the physiological response of Chlorella vulgaris exposed to As (V), and the underlying mechanism were investigated under different phosphorus (P) levels (0, 6, 13, 32 μM). Results showed that As toxicity to the marine microalga C. vulgaris was enhanced under P-limited condition. P supply distinctly altered the effect of As on the light-harvesting efficiency of photosystem. Insufficient P supply also resulted in an enhanced level of membrane integrity loss, which probably facilitated As entering cells and led to stronger toxicity to C. vulgaris under low P supply. At high concentrations of As, the relative superoxide dismutase (SOD) activity was significantly enhanced. When phosphorus was limited, the activation of peroxidase (POD) was significantly enhanced after adding As (V). When intracellular SOD activity was at its highest level, the level of membrane peroxidation (MDA) was also at the highest level, and membrane peroxidation level was positively related to the level of membrane integrity loss (Pearson R²=0.8977). These results suggested that alternation of light-harvesting efficiency of photosystem and As-induced oxidative damage, resulting in membrane peroxidation and integrity loss, were the possible mechanism of As toxicity to C. vulgaris. This study provided insight into the understanding of As toxicity to algae in the eutrophication aquatic system and the potential application of algae in As remediation.

Using ecosystem-services assessments to determine trade-offs in ecosystem-based management of marine mammals

The goal of ecosystem-based management (EBM) is to support a sustainable and holistic multisectored management approach, and is recognized in a number of international policy frameworks. However, it remains unknown how these goals should be linked to assessments and management plans for marine fauna, such as mammals and fish stocks. It appears particularly challenging to carry out trade-off analyses of various ocean uses without a framework that integrates knowledge of environmental, social, and economic benefits derived from nonstationary marine fauna. We argue this gap can be filled by applying a version of the ecosystem-service approach at the population level of marine fauna. To advance this idea, we used marine mammals as a case study to demonstrate what indicators could operationalize relevant assessments and deliver an evidence base for the presence of ecosystem services and disservices derived from marine mammals. We found indicators covering common ecosystem service categories feasible to apply; examples of indicator data are already available in the literature for several populations. We encourage further exploration of this approach for application to marina fauna and biodiversity management, with the caveat that conceptual tensions related to the use of the ecosystem service concept itself needs to be addressed to ensure acceptance by relevant stakeholders.

From Mexico to the Beagle Channel: A review of metal and metalloid pollution studies on wildlife species in Latin America

Emissions of metals and metalloids (Hg; Cd; Cr; Cu; Pb; Ni; Zn; Fe; Mn; As; Se) generated by natural (e.g., geothermal activity) or anthropic causes (eg., industry or mining) represent a worldwide contamination problem, especially in developing countries. Exposure to high concentrations of these elements is harmful to living beings, including humans. Information on this type of contamination is scarce and fragmented, limiting research which could benefit from these data. To know the state of the research, we reviewed the studies of environmental pollution by metals and metalloids carried out on animal species in Latin America. The use of animals as biomonitors of contamination by metals and metalloids is a continuously expanding practice that allows for early detection of problems. With this work, we were able to identify the most studied areas in Latin America (Amazon, Gulf of California, coastal area between Rio de Janeiro and Florianopolis and River Plate Estuary). Moreover, we provide information on the most studied metals (Hg, Cd, Cu, Pb, Zn) and wild species, which evidence the use of endangered species. The data reviewed should help researchers to direct their efforts towards sparsely researched areas and facilitate bibliographic consultation of scientific information on exposure to metals and metalloids in Latin America.

Global assessment of cadmium concentrations in the skin of free-ranging sperm whales (Physeter macrocephalus)

Cadmium is a non-essential, toxic metal found accumulated in the organs of stranded cetaceans. Currently, there is no baseline cadmium concentration reported in a free-ranging, pelagic cetacean. The aim was to determine cadmium concentrations in the skin of free-ranging sperm whales (n=340) collected from 16 regions around the world during the voyage of the Odyssey (2000-2005) considering region, gender, and age in males. Cadmium was detected in 81% of skin biopsies with a mean of 0.3±0.04μg/g ww (0.02 to 12.4μg/g ww). These concentrations were higher than reported in literature in toothed whale skin (0.002-0.1μg/g ww). Concentrations by region were significantly different (p<0.0001) with the highest mean in Maldives and the Sea of Cortez (0.8 and 0.6μg/g ww, respectively). There was no significant difference in cadmium concentration by gender (p=0.42). Cadmium is known to have a long biological half-life, and cadmium concentrations in males were significantly higher in adults with a mean of 0.3μg/g ww compared to subadults with 0.2μg/g ww (p=0.03). Selenium, an element that binds to cadmium inhibiting its toxicity, had a moderately positive correlation with cadmium (r=0.41). Mercury, a toxic metal that positively correlates with cadmium in cetacean tissue, had a weakly positive relationship (r=0.20). The regional baselines reported in this study may be used to develop residue criteria for prediction of toxicological risk in sperm whale skin. Additionally, this study shows the extent of cadmium exposure in a pelagic cetacean that has global distribution.

Comparative cytotoxicity and genotoxicity of soluble and particulate hexavalent chromium in human and hawksbill sea turtle (Eretmochelys imbricata) skin cells

Chromium is both a global marine pollutant and a known human health hazard. In this study, we compare the cytotoxicity and genotoxicity of both soluble and particulate chromate in human and hawksbill sea turtle (Eretmochelys imbricata) skin fibroblasts. Our data show that both soluble and particulate Cr(VI) induce concentration-dependent increases in cytotoxicity, genotoxicity, and intracellular Cr ion concentrations in both human and hawksbill sea turtle fibroblasts. Based on administered concentration, particulate and soluble Cr(VI) were more cytotoxic and clastogenic to human cells than sea turtle cells. When the analysis was based on the intracellular concentration of Cr, the data showed that the response of both species was similar. The one exception was the cytotoxicity of intracellular Cr ions from soluble Cr(VI), which caused more cytotoxicity in sea turtle cells (LC50=271μM) than that of human cells (LC50=471μM), but its clastogenicity was similar between the two species. Thus, adjusting for differences in uptake indicated that the explanation for the difference in potency was mostly due to uptake rather than differently affected mechanisms. Overall these data indicate that sea turtles may be a useful sentinel for human health responses to marine pollution.