A global systematic review, meta-analysis, and risk assessment of the concentration of vanadium in drinking water resources.

The presence of toxic metals such as vanadium in water resources has attracted considerable attention as a new concern in international health. Systematic review and meta-analysis were performed to assess the concentration of vanadium in water resources along with the relevant ecological risk assessment. Databases of Scopus, PubMed, and Embase were investigated to retrieve the related articles from January 01, 1974 to December 25, 2019. Twenty-eight articles containing 152 samples from 24 countries were included. Furthermore, the meta-analysis was conducted by the approach of z-score to estimate differences in the effect size. In addition, the mean of concentrations of vanadium was applied to calculate the risk assessment only to the water surface and choose the maximum environmental concentration (MEC) for demonstrate a worst-case scenario. Here, the risk assessment approach was used to show that the MEC of vanadium confirm the risk it for aquatic ecosystems, being fish (e.g., Danio rerio) our model organism due to their sensibility. According to findings, the MEC of vanadium in surface water varied from 0.010 µg L-1 (USA) and 68 µg L-1 (China), with an overall mean of 6.21 ± 13.3 µg L-1 (mean ± standard deviation). The ecological risk assessment demonstrated that people living in some countries such as China and Japan were at an adverse ecological risk of vanadium in the water resources. Hence, essential control plans besides adequate removal techniques must be implemented for significant deracination of heavy metals like vanadium.

Ciliates as model organisms for the ecotoxicological risk assessment of heavy metals: A meta-analysis.

Ciliates are key components of aquatic ecosystems, significantly contributing to the decomposition of organic matter and energy transfer to higher trophic levels. They are considered good biological indicators of chemical pollution and relatively sensitive to heavy metal contamination. In this study, we performed a meta-analysis of the available toxicity data of heavy metals and ciliates to assess: (1) the sensitivity of freshwater ciliates to different heavy metals, (2) the relative sensitivity of ciliates in comparison to the standard test species used in ecotoxicological risk assessment, and (3) the difference in sensitivity across ciliate taxa. Our study shows that the tolerance of ciliates to heavy metals varies notably, which is partly influenced by differences in methodological conditions across studies. Ciliates are, in general, sensitive to Mercury > Cadmium > Copper > Zinc > Lead > Chromium. Also, this study shows that most ciliates are more tolerant to heavy metal pollution than the standard test species used in ecotoxicological risk assessments, i.e., Raphidocelis subcapitata, Daphnia magna, and Onchornyncus mykiss. Threshold concentrations derived from toxicity data for these species is expected to confer sufficient protection for the vast majority of ciliate species. Our data analysis also shows that the most commonly tested ciliate species, Paramecium caudatum and Tetrahymena thermophila, are not necessarily the most sensitive ones to heavy metal pollution. Finally, this study stresses the importance of developing standard toxicity test protocols for ciliates, which could lead to a better comprehension of the toxicological impact of heavy metals and other contaminants to ciliate species.