Immobilization of elemental mercury by biogenic Se nanoparticles in soils of varying salinity

Abstract

Salinity can be a significant environmental stress which can govern the fate of nanoparticles in the environment as well as other factors such as pH, natural organic matter and minerals. In this research, the effects of salinity on the behaviour of biogenic selenium nanoparticles (BioSeNPs) and consequences for elemental mercury (Hg 0 ) immobilization in soil and soil solutions were investigated. It was found that homoaggregation and sedimentation of BioSeNPs were enhanced significantly with increasing salinity. Compression of the electric double layers of BioSeNPs at high ionic strengths resulted in attractive van der Waals forces dominating and leading to enhanced aggregation. Moreover, neutralization of the surface negative charge of BioSeNPs by divalent cations and the bridging of BioSeNPs via calcium binding to surface functional groups were also associated with enhanced aggregation. Such enhanced aggregation exerted inhibition of Hg 0 immobilization in soil solutions/soils of varying salinity. These results indicate that salinity is an important environmental factor governing aggregation of BioSeNPs and therefore influencing the efficiency of Hg 0 immobilization, and possible remediation treatments, as a consequence.

Selenium and Nano-Selenium Biofortification for Human Health: Opportunities and Challenges

“…Further investigations are needed to monitor the behavior of Se-NPs in different environments including agricultural soils, waters, and farm animals. Se-NPs have already been used in the remediation of soils and waters that were contaminated with heavy metals like mercury [225][226][227]. This work confirmed that soils and groundwater contaminated with elemental mercury could be remediated via biogenic Se-NPs based on mechanisms like the immobilization of elemental mercury [226,227], applied hetero-aggregation of soil particulate organic matter [225], applied biofilm-coated quartz sand [228], and applied goethite colloids [138] in the presence of Se-NPs [64].…”

“…Se-NPs have already been used in the remediation of soils and waters that were contaminated with heavy metals like mercury [225][226][227]. This work confirmed that soils and groundwater contaminated with elemental mercury could be remediated via biogenic Se-NPs based on mechanisms like the immobilization of elemental mercury [226,227], applied hetero-aggregation of soil particulate organic matter [225], applied biofilm-coated quartz sand [228], and applied goethite colloids [138] in the presence of Se-NPs [64]. Further investigations are needed to monitor the behavior of Se-NPs in different environments including agricultural soils, waters, and farm animals.…”

Selenium nanoparticles: a review on synthesis and biomedical applications

“…There is a tremendous amount of literature available on the biosynthesis of SeNPs. 80–87 Biological agent mediated synthesis is easy as this does not require special apparatus and conditions. These biological reagents include bacteria, fungi, algae, protein molecules and plant extracts.…”

“…It is reported that biological extracts act as bioreducing agents, as well as stabilizers for nanoparticles. There is tremendous amount of literature available on the biosynthesis of SeNPs [80][81][82][83][84][85][86][87] . The biological agent mediated synthesis is easy as this does not require special apparatus and conditions.…”

Bioaccumulation of Hg in Rice Leaf Facilitates Selenium Bioaccumulation in Rice (Oryza sativa L.) Leaf in the Wanshan Mercury Mine

“…At nonartisanal mining sites, a positive correlation between TGM and soil THg can be observed ( r 2 = 0.82, p < 0.01), suggesting that TGM mainly originated from the in situ emission of Hg 0 from the soil. It is likely the elevated soil TSe at nonartisanal mining sites can reduce the bioavailability of soil Hg or the emission of Hg 0 from the soil, through the formation of less soluble HgSe in soil. − At artisanal mining sites, however, we did not observe any clear correlation between soil TSe and BAFs of Hg in rice tissues (Figure B). Unlike nonartisanal mining sites, no significant correlation between TGM and soil THg was observed at artisanal mining sites, suggesting that the TGM was not mainly emitted from soil, but directly from artisanal mining activities.…”