Selenium volatilization in plants, microalgae, and microorganisms

Abstract

The augmented prevalence of Se (Se) pollution can be attributed to various human activities, such as mining, coal combustion, oil extraction and refining, and agricultural irrigation. Although Se is vital for animals, humans, and microorganisms, excessive concentrations of this element can give rise to potential hazards. Consequently, numerous approaches have been devised to mitigate Se pollution, encompassing physicochemical techniques and bioremediation. The recognition of Se volatilization as a potential strategy for mitigating Se pollution in contaminated environments is underscored in this review. This study delves into the volatilization mechanisms in various organisms, including plants, microalgae, and microorganisms. By assessing the efficacy of Se removal and identifying the rate-limiting steps associated with volatilization, this paper provides insightful recommendations for Se mitigation. Constructed wetlands are a cost-effective and environmentally friendly alternative in the treatment of Se volatilization. The fate, behavior, bioavailability, and toxicity of Se within complex environmental systems are comprehensively reviewed. This knowledge forms the basis for developing management plans that aimed at mitigating Se contamination in wetlands and protecting the associated ecosystems.

Keywords: Microalgae; Microorganisms; Plants; Selenium; Volatilization; Wetland ecosystems.

Fig. 1

Selenium metabolism in plants' tissues. (APS, ATP sulfurylase; APR, APS reductase; CS, Cysteine synthase; OAS, O-acetylserine; SL, Selenocysteine lyase; SMT, Selenocysteine methyl transferase).

Fig. 2

A brief volatilization pathway in microalgal cells.

Fig. 3

Schematic illustration of the hypothesized biochemical mechanism by which Chlorella vulgaris transforms selenate into selenocyanate.

Fig. 4

Conversion of selenium by microorganisms in soil.