Assessment of the Temporal and Spatial Variation of the Mercury Content of Lake Nokoué in Southern Benin Republic (West Africa)

Anthropogenic input of mercury into watersheds is becoming increasingly noticeable and is the cause of fishery products contamination. This had led to the Convention of Minamata signed and ratified by the vast majority of the countries in the world. Lake Nokoué in Benin Republic, the most fishery products provider in West Africa, is subject to mercury pollution. The health threat to both the benthic and the consumers of the fishery products from this lake has to be anticipated by precisely determining the dynamics of mercury contamination of the waters and sediments of Lake Nokoué, taking into account the anthropogenic contribution. Water and sediment samples were collected on 23 sites twice a month for four sampling campaigns. Parameters such as pH, salinity, COD, and SS are evaluated in the water. The assessment of total mercury is conducted by cold vapor atomic absorption according to the US EPA 7473 method, using a direct mercury analyzer (DMA-80). On average, the mercury content in Lake Nokoué water is 0.43 ± 0.57 μg/kg. Its variation is linked not only to the seasonal variation but also to that of the suspended matter. South of the lake, the sediments are extremely polluted (5 ≤ Igeo) and present a risk of frequent effects for the benthic species present.

Study of Heavy Metals Pollution and Vitellogenin Levels in Brown Trout (Salmo trutta trutta) Wild Fish Populations

The objectives of this research were, first, to determine the concentrations of certain heavy metals in the edible tissue of wild brown trout (Salmo trutta trutta) from two different rivers located in the Abruzzi region (Italy), and then, to investigate the levels of variation in vitellogenin (VTG) associated with the presence of metalloestrogens. VTG is an effective indicator for endocrine disturbance, and an increase in the vitellogenin levels in male fish is widely employed as a biomarker of estrogenic contamination in the aquatic environment. The muscles of the trout were analyzed for As, Cd, Co, Cr, Ni, Pb, Al, and Zn using an inductively coupled plasma-mass spectrometer (ICP-MS), and Hg was measured using a direct mercury analyzer (DMA-80). The calculated values of the condition factor confirmed a healthy status for this species, indicating that the aquatic habit in both rivers is suitable for brown trout life. No significant difference in the concentrations of each metal were reported between the trout from the two rivers, and no significant difference for VTG levels were found between male and female fish. It is interesting to note the high concentrations of Al/Zn, while the Pb, Cd, and Hg concentrations in all of the samples were lower than those established by the European Commission.

Direct Mercury Analyzer (DMA) determination of mercury distribution in the sediments of lake Nokoué in Benin Republic-West Africa

Mercury pollution of water bodies constitutes a hazard to both the aquatic life and the populations consuming fishery products. To anticipate the probable eco-toxicological risks that may arise from the largest lake in southern Benin, the present work aims at assessing the mercury status of the sediments of Lake Nokoué, while identifying the areas exposed to anthropogenic mercury contamination. 45 sites were sampled according to a grid plan covering the entire ecosystem of the lake. Employing a Van Veen grab, surface sediments are collected at a depth from 0 to 5 cm in three catches at each site. The composite samples formed at equal mass on the three portions were frozen, lyophilized at - 40 °C, crushed, sieved and homogenized. Fraction less than 63 µm was collected for the mercury content determination by Direct Mercury Analyzer (DMA) operating by atomic absorption according to the US EPA 7473 method. The mercury concentration varies from 1.56 µg/kg to 164.88 µg/kg with an average value of 35.18 µg per kg of sediment. The south-eastern zone of the lake is more concentrated in mercury with a summation of the mercury content of 530.3 µg/kg of sediment. However, the lake has moderate contamination overall (1 ≤ FC ≤ 3). Keywords: Pollution, contamination, mercury, sediment, Lake Nokoué.

Total mercury in rice plant (Oryza sativa) collected from Sekinchan, Selangor, Malaysia and associated health risks

Consumption of mercury-contaminated rice could pose a potential health risk to humans. In this study, total mercury (THg) concentrations in various parts (roots, stems, leaves, and grains) of rice plant (Oryza sativa) collected from Sekinchan, Selangor, Malaysia were analysed for risk assessment. The THg concentrations in collected samples were analysed by Direct Mercury Analyzer (DMA-80). The mean concentrations found in plant parts were as follows: root, 47.01±0.42 µg/kg; stem, 6.43±1.77 µg/kg; leaf, 26.25±4.71 µg/kg; grain, 2.64±0.42 µg/kg. THg distribution in rice plants was roots > leaves > stems and grains. The mean THg concentration in grain (2.64±0.42 µg/kg) was below the maximum permitted proportion stipulated by Malaysian Food Regulation 1985 (50.0 µg/ kg). The estimated weekly intake (EWI) of THg through rice was 0.07±0.01 µg/kg bw/ week for 60 kg adult, below the provisional tolerable weekly intakes (PTWI) as suggested by JECFA indicating unlikely to cause impairment of public health due to consumption of rice planted in this region. However, periodical monitoring of mercury pollution in Selangor area is crucial because mercury contamination in crops could jeopardize food safety and security

Mercury content of sarotherodon melanotheron and chrysischthys nigrodigitatus of Lake Nokoue and Porto Novo lagoon in Benin

Ratification of Minamata Convention by Bénin requires identification of contaminated sites and preservation of health. In this context, the Ministry of Living Environment and Sustainable Development supported the study by making its mercury analyzer DMA80 available. The study aims to identify the level of mercury contamination in two highly valued fish species caught in one of the most productive water bodies where mercury is reported. So, three monthly sample collection campaigns were carried out from April to juin 2018 at nine (09) sites. The back flesh of sarotherodon melanotheron and chrysischthys nigrodigitatus of lake Nokoue and Porto Novo lagoon was analyzed by direct mercury analyzer (DMA 80). it Its operating principle is atomic absorption after thermal decomposition coupled with a gold sensor. The average mercury contents are 20.8 ± 15.5 μg / kg and 6.5 ± 3.8 wet μg / kg weight respectively for Chrysichthys nigrodigitatus and Sarotherodon melanotheron. The highest values obtained at the Porto-Novo bridge for both species remain well below the standard (0.5 mg / kg wet weight). With consumption habits of fish in Benin, the weekly exposure doses seem to be much lower than WHO recommendation. However, deepened studies are needed.Keywords: Fish, mercury, spatial distribution, NoKoué Lake, Porto-Novo Lagoon.

Hg Levels in Marine Porifera of Montecristo and Giglio Islands (Tuscan Archipelago, Italy)

Porifera are filter-feeding organisms known to bioaccumulate different contaminants in their tissues. The presence of mercury (Hg) has been reported in different Mediterranean species, mainly collected in the southern coast of France. In the present study, mercury concentrations in the tissue of the sponges of Montecristo and Giglio, two islands of Tuscany Archipelago National Park (TANP), are presented for the first time. Analyses of total mercury content were performed by Direct Mercury Analyzer. Statistical differences have been reported in the Hg concentrations of species collected in both islands, but they do not appear related to the anthropic impacts of the islands. Among the collected species, a high intra- and inter-variability have been recorded, with Cliona viridis showing the lowest concentration (0.0167–0.033 mg·kg−1 dry weight), and Chondrosia reniformis and Sarcotragus spinosulus the highest (0.57 ± 0.15 and 0.64 ± 0.01 mg·kg−1 dry weight, respectively). The variability of Hg measured did not allow us to identify sponges as bioindicators of toxic elements. Anyway, these results improve knowledge on the ecosystem of the TANP, underlining the species-specificity of metal concentrations for Porifera, and providing additional data to address the main input of the Marine Strategy guidelines to protect coasts, seas and oceans.