Prediction of methylmercury accumulation in rice grains by chemical extraction methods

Zhu, Daiwen; Zhong, Huan; Zeng, Qing‐Yin; Yin, Ying

doi:10.1016/j.envpol.2015.01.015

Cited by 36 publications

(11 citation statements)

References 71 publications

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“…Similar patterns of increased MeHg bioaccumulation that had been formed from newly added IHg have been previously observed (Mao et al, 2013). MeHg in soils is bound in several pools of varying bioavailability to rice plants (Zhu et al, 2015), and newly formed MeHg may indeed be more available for phytouptake. Overall, as others have hypothesized, it is likely that soil MeHg formed in the soil partitions to pore water and enters the roots (Schwesig and Krebs, 2003), travels to the straw via the phloem/symplastic network (Rothenberg et al, 2015), and then accumulates in the developing grain, possibly as a MeHg-cysteine complex .…”

Section: Methylmercurysupporting

confidence: 75%

Methylmercury in Managed Wetlands

Strickman

Mitchell

2017

Multifunctional Wetlands

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Methylmercury (MeHg), a bioaccumulative neurotoxin, is microbially produced in anoxic wetland environments. The direct or indirect management of wetlands is pervasive, but many questions remain regarding the impact of wetland management on MeHg biogeochemistry. To address this, I investigated the extent, drivers, and consequences of MeHg production in important types of managed wetlands, as well as the response of MeHg to specific management interventions. In a field study which simulated industrial increases and legislated decreases in Firstly, I would like to thank my advisors, Carl Mitchell, Roberta Fulthorpe, and Marney Isaac, for their support, guidance, and understanding as I navigated through not only a Ph.D., but a new country, marriage and parenthood. I will always be particularly grateful for your enthusiastic support for my pursuit of my own research ideas, which was a true privilege. In addition, I would like to thank Shelley Eisner, Elaine Pick, and Jennifer Caradonna of the DPES administrative support team for their quick and helpful responses to all my administrative questions. Eventually I even reached the point of filling out expense claims without mistakes, at least once or twice! I would also like to extend a particular thank you to Planck (Haiyong) Huang for his endless patience and good nature as he demonstrated laboratory techniques, bringing a smile to even the most frustrating day with the ICP-MS. Research can be lonely, but I was so fortunate to have wonderful PhD colleagues with whom to share frustrations, ideas, and XKCD cartoons. In particular, Ingjerd Sunde Krogseth, Johnny Westgate, Nicole Ricker, Rosemary Saati, and Carlos Paulo made the ninety minute commute worth it. A big thank you also to my "science pals" near and far, especially Annett Schumacher and Zoe Goodwin for their ongoing moral support! Finally, a special thank you to my close friends Diana Cousminer and Genevieve Noyce, and their families Rachel Kahan-Noyce, Ami Ganguli, Elliott Lehtonen, and Misha Ganguli, for their company and support as we wrote up PhDs from each other's kitchen tables-a special kind of enjoyment, to work from home with people who understand what the work is about! Thank you to my parents, Dan and Linda Strickman, my sisters Leah and Rose, and my brother in law Laurence Scott-for five years of reality checks, commiseration, and advice both critical and partisan. I'd also like to thank my family by marriage, the Lombardi-Spanos, for so many great family meals and parties to take my mind off methylmercury and R! My love and gratitude go to my husband, Luciano Lombardi, who was always there for me when I needed him, in so many ways. And finally, in subject and in spirit, this thesis turned out to be for my son, Daniel, who has made it all worthwhile. x Preface Although I am the primary author of this thesis, others have made important contributions, which I outline below. Chapters 2, 4, and 5 are either published, or in review for publication, and necessarily contain some repetition of methods and bac...

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Section: Methylmercurysupporting

confidence: 75%

Methylmercury in Managed Wetlands

Strickman

Mitchell

2017

Multifunctional Wetlands

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“…to remove pore water and amended with (NH 4 ) 2 S 2 O 3 solution (0.0135 mol/L) at a 1:2 ratio, and then were rotated at 250 rpm per minute overnight in a shaker [17]. The mixtures were centrifuged at 3,000 rpm for 30 min.…”

Section: Methodsmentioning

confidence: 99%

“…4. Significant relationships between rice grain MeHg levels and (NH 4 ) 2 S 2 O 3 -extracted MeHg of soil have been reported, and (NH 4 ) 2 S 2 O 3 extraction may mimic MeHg uptake by roots and its accumulation in rice plants [17]. Therefore, MeHg concentrations extracted from soils were used to indicate potential …”

Section: Bioaccumulation Of Inorganic Mercury and Mehg In Rice Plantsmentioning

confidence: 99%

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The Bioaccumulation and Migration of Inorganic Mercury and Methylmercury in the Rice Plants

Zhu¹,

Han²,

Wu³

2017

Pol. J. Environ. Stud.

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“…This measure should only be considered semi-quantitative as the bioavailable fractions of inorganic Hg and MeHg are not known or readily quantiable. 37 However, the product of K meth and the solid phase inorganic mercury pool (with which it is reacting) is a more intuitive measurement than the raw K meth potential (units of d À1 ) because the product accounts for the pool of reactant. Ratios of these potential rates (each having units of ng g À1 d À1 ) above one suggest the potential for net methylation and ratios of these potential rates below one suggest the potential for net demethylation.…”

Section: Methodsmentioning

confidence: 99%

Methylmercury production in a chronically sulfate-impacted sub-boreal wetland

Johnson

Mitchell

Engstrom

et al. 2016

Environ. Sci.: Processes Impacts

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Increased deposition of atmospheric sulfate exacerbates methylmercury (MeHg) production in freshwater wetlands by stimulating methylating bacteria, but it is unclear how methylation in sub-boreal wetlands is impacted by chronically elevated sulfate inputs, such as through mine discharges. The purpose of our study is to determine how sulfate discharges to wetlands from iron mining activities impact MeHg production. In this study, we compare spatial and temporal patterns in MeHg and associated geochemistry in two wetlands receiving contrasting loads of sulfate. Two orders of magnitude less sulfate in the un-impacted wetland create significant differences in acid-volatile sulfide and porewater sulfide; however, dissolved and solid-phase MeHg concentrations and methylation rate potentials (Kmeth) are statistically similar in both wetlands. Permitted mine pumping events flood the sulfate-impacted wetland with very high sulfate waters during the fall. In contrast to observations in sulfate-limited systems, this large input of sulfate to a chronically sulfate-impacted system led to significantly lower potential relative methylation rates, suggesting a predominance of demethylation processes over methylation processes during the sulfate loading. Overall, short-term measurements of methylation and demethylation potential are unrelated to gross measures of long-term MeHg accumulation, indicating a decoupling of short- and long-term process measurements and an overall disequilibrium in the systems. High sulfide accumulation, above ∼600-800 μg l(-1) sulfide, in the sulfate-impacted system lowers long-term MeHg accumulation, perhaps as a result of less bioavailable Hg-S complexes. Although continued research is required to determine how sulfate-limited freshwater wetlands might respond to new, large inputs of high-sulfate runoff from mining operations, chronically impacted wetlands do not appear to continually accumulate or produce MeHg at rates different from wetlands unimpacted by mining.

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Prediction of methylmercury accumulation in rice grains by chemical extraction methods

Cited by 36 publications

References 71 publications

Methylmercury in Managed Wetlands

Methylmercury in Managed Wetlands

The Bioaccumulation and Migration of Inorganic Mercury and Methylmercury in the Rice Plants

Methylmercury production in a chronically sulfate-impacted sub-boreal wetland

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