Interaction of Naturally Occurring Phytoplankton with the Biogeochemical Cycling of Mercury in Aquatic Environments and Its Effects on Global Hg Pollution and Public Health

Abstract

The biogeochemical cycling of mercury in aquatic environments is a complex process driven by various factors, such as ambient temperature, seasonal variations, methylating bacteria activity, dissolved oxygen levels, and Hg interaction with dissolved organic matter (DOM). As a consequence, part of the Hg contamination from anthropogenic activity that was buried in sediments is reinserted into water columns mainly in highly toxic organic Hg forms (methylmercury, dimethylmercury, etc.). This is especially prominent in the coastal shallow waters of industrial regions worldwide. The main entrance point of these highly toxic Hg forms in the aquatic food web is the naturally occurring phytoplankton. Hg availability, intake, effect on population size, cell toxicity, eventual biotransformation, and intracellular stability in phytoplankton are of the greatest importance for human health, having in mind that such Hg incorporated inside the phytoplankton cells due to biomagnification effects eventually ends up in aquatic wildlife, fish, seafood, and in the human diet. This review summarizes recent findings on the topic of organic Hg form interaction with natural phytoplankton and offers new insight into the matter with possible directions of future research for the prevention of Hg biomagnification in the scope of climate change and global pollution increase scenarios.

Bioconcentration of Inorganic and Methyl Mercury by Algae Revealed Using Dual-Mass Single-Cell ICP-MS with Double Isotope Tracers

“…It is widely recognized that MeHg can be transferred more efficiently than IHg in the food web. 1,7,8,16 In fact, we noted that there were already differences between the IHg and MeHg bioconcentrations at the primary producer stage. Hg bioconcentration by algae was demonstrated to be a dynamic equilibrium process involving influx/adsorption and efflux/desorption.…”

“…8,14 Adsorption and absorption of IHg and MeHg by algae significantly affect the form, concentration, and fate of Hg in water. 13,15,16 Investigation of the distribution of IHg and MeHg between ambient water and algae is important for understanding the biogeochemical cycling of Hg and its environmental risk.…”

“…It was estimated that up to 20% of anthropogenic Hg emissions could be trapped in the algae-derived siliceous sediments . IHg on algae can also be further involved in other Hg transformation processes. , In particular, IHg on decaying algae can be transformed into MeHg by microbial-mediated methylation, resulting in an increase of MeHg in the water column. , Adsorption and absorption of IHg and MeHg by algae significantly affect the form, concentration, and fate of Hg in water. ,, Investigation of the distribution of IHg and MeHg between ambient water and algae is important for understanding the biogeochemical cycling of Hg and its environmental risk.…”

Emerging contaminants: A One Health perspective

“…These contaminants can interfere with cellular functions, impair reproduction, and cause behavioral changes in fish and invertebrates. 410 , 411 Accumulation of organometals in sediments may have long-term implications for benthic communities. Oil spills and organic solvents, including methyl tert -butyl ether (MTBE), can contaminate habitats.…”

A Retrospection on Mercury Contamination, Bioaccumulation, and Toxicity in Diverse Environments: Current Insights and Future Prospects

“…The toxicity of Hg to microalgae is majorly due to its interaction with SH groups of the enzymes and imparting OS. Hg inside the algal cells were observed to bind to cytosolic ligands and block the functional groups of important enzymes there by altering their confirmation and functional properties [130].…”