Mercury transformation and release differs with depth and time in a contaminated riparian soil during simulated flooding

Poulin, Brett A.; Aiken, George R.; Nagy, Kathryn L.; Manceau, Alain; Krabbenhoft, David P.; Ryan, Joseph N.

doi:10.1016/j.gca.2015.12.024

Cited by 60 publications

(34 citation statements)

References 104 publications

(230 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This increase in THg concentrations is likely due to the lack of formation of biogenic sulfide. This observation is consistent with a previous study [37], in which aqueous concentrations of THg were observed to be highly variable in response to redox oscillations in a microcosm experiment containing riparian soils.…”

Section: Ph Redox Potential and Alkalinitysupporting

confidence: 93%

Stabilization of mercury in sediment by using biochars under reducing conditions

Liu

Ptacek

Blowes

et al. 2017

Journal of Hazardous Materials

View full text Add to dashboard Cite

Mercury (Hg) is widely distributed in different localities around the world and poses a serious health threat to humans, especially when ingested in the form of methylmercury (MeHg). Efforts have been directed toward decreasing the production of MeHg by converting Hg to stable forms. Activated carbon and biochar have been evaluated as stabilization agents for Hg in contaminated sediments. However, the long-term fate of Hg stabilized by these materials remains unclear. Here, we compare the effectiveness of Hg stabilization using two biochars prepared from switchgrass at 300°C (lowT) and 600°C (highT). Experiments were conducted by co-blending biochars and sediment for >600 d under anaerobic conditions. Aqueous concentrations of total Hg and MeHg were greatly reduced in the presence of biochars, with the exception of a spike in MeHg concentration observed at ∼440 d in the high-T biochar system. Hg co-occurs with S, Fe, Cu, and other elements within the plant structure of low-T biochar particles, but primarily on the outer surfaces of high-T biochar particles. Our results indicate that the stabilization of Hg may be through an early-stage diagenetic process, suggesting that the stabilization of Hg by biochar may be effective over long time frames.

show abstract

Section: Ph Redox Potential and Alkalinitysupporting

confidence: 93%

Stabilization of mercury in sediment by using biochars under reducing conditions

Liu

Ptacek

Blowes

et al. 2017

Journal of Hazardous Materials

View full text Add to dashboard Cite

show abstract

“…Hg 0 oxidation is thought to be more important in situations where thiol binding site availability is high relative to low extracellular Hg concentration (Lin et al 2014b). Given the ubiquitous nature of thiols in bacterial membranes (Yu et al 2014), Hg 0 oxidation by anaerobes is likely widespread in environments such as waterlogged soils (Mazur et al 2015;Poulin et al 2016) and anoxic lake sediments (Bouffard and Amyot 2009) where Hg 0 can dominate Hg speciation. When considered alongside the growing evidence for anaerobic Hg II reduction, these findings show that anaerobes are poised to be key players in controlling MeHg production in anoxic systems by catalyzing a dynamic anaerobic redox cycle.…”

Section: Chemotrophic Mercury Oxidationmentioning

confidence: 99%

Shining light on recent advances in microbial mercury cycling

Grégoire

Poulain

2018

FACETS

View full text Add to dashboard Cite

Mercury (Hg) is a global pollutant emitted primarily as gaseous Hg0 that is deposited in aquatic and terrestrial ecosystems following its oxidation to HgII. From that point, microbes play a key role in determining Hg’s fate in the environment by participating in sequestration, oxidation, reduction, and methylation reactions. A wide diversity of chemotrophic and phototrophic microbes occupying oxic and anoxic habitats are known to participate directly in Hg cycling. Over the last few years, new findings have come to light that have greatly improved our mechanistic understanding of microbe-mediated Hg cycling pathways in the environment. In this review, we summarize recent advances in microbially mediated Hg cycling and take the opportunity to compare the relatively well-studied chemotrophic pathways to poorly understood phototrophic pathways. We present how the use of genomic and analytical tools can be used to understand Hg transformations and the physiological context of recently discovered cometabolic Hg transformations supported in anaerobes and phototrophs. Finally, we propose a conceptual framework that emphasizes the role that phototrophs play in environmental Hg redox cycling and the importance of better characterizing such pathways in the face of the environmental changes currently underway.

show abstract

“…In general, Hg in soils and sediments is controlled by inorganic and organic interactions, since it has an affinity to Cl − , OH − , S 2− , and S-containing functional thiol groups in organic ligands [7][8][9]. Organic matter can both mobilize and immobilize Hg, depending on the prevailing soil pH, redox, and flooding conditions [10][11][12][13]. In addition, in well-oxygenated soils, Hg can be mobilized by the presence of high concentrations of Cl − ions [14] that act as a complexing agent, and conditions potentially found in areas with high usage of road deicing salts [15].…”

Section: Introductionmentioning

confidence: 99%

Speciation and Mobility of Mercury in Soils Contaminated by Legacy Emissions from a Chemical Factory in the Rhône Valley in Canton of Valais, Switzerland

et al. 2018

View full text Add to dashboard Cite

Legacy contamination of soils and sediments with mercury (Hg) can pose serious threats to the environment and to human health. Assessing risks and possible remediation strategies must consider the chemical forms of Hg, as different Hg species exhibit vastly different environmental behaviors and toxicities. Here, we present a study on Hg speciation and potential mobility in sediments from a chemical factory site, and soils from nearby settlement areas in the canton of Valais, Switzerland. Total Hg ranged from 0.5 to 28.4 mg/kg in the soils, and 3.5 to 174.7 mg/kg in the sediments, respectively. Elemental Hg(0) was not detectable in the soils by thermal desorption analysis. Methylmercury, the most toxic form of Hg, was present at low levels in all soils (<0.010 mg/kg; <0.8% of total Hg). Sequential extractions and thermal desorption analyses suggested that most of the Hg in the soils was present as “matrix-bound Hg(II)”, most likely associated with soil organic matter. For factory sediments, which contained less organic matter, the results suggested a higher fraction of sulfide-bound Hg. Batch extractions in different CaCl2 solutions revealed that Hg solubility was low overall, and there was no Hg-mobilizing effects of Ca2+ or Cl− in solution. Only in some of the factory sediments did high CaCl2 concentrations result in increased extractability of Hg, due to the formation of Hg-chloride complexes. Additional experiments with soil redox reactors showed that even mildly reducing conditions led to a sharp release of Hg into solution, which may be highly relevant in soils that are prone to periodic water saturation of flooding.

show abstract

Mercury transformation and release differs with depth and time in a contaminated riparian soil during simulated flooding

Cited by 60 publications

References 104 publications

Stabilization of mercury in sediment by using biochars under reducing conditions

Stabilization of mercury in sediment by using biochars under reducing conditions

Shining light on recent advances in microbial mercury cycling

Speciation and Mobility of Mercury in Soils Contaminated by Legacy Emissions from a Chemical Factory in the Rhône Valley in Canton of Valais, Switzerland

Contact Info

Product

Resources

About