Mercury cycling in agricultural and managed wetlands: A synthesis of methylmercury production, hydrologic export, and bioaccumulation from an integrated field study

Windham‐Myers, Lisamarie; Fleck, Jacob A.; Ackerman, Joshua T.; Marvin-DiPasquale, Mark C.; Stricker, Craig A.; Heim, Wesley A.; Bachand, Philip A.M.; Eagles‐Smith, Collin A.; Gill, Gary A.; Stephenson, Mark; Alpers, Charles N.

doi:10.1016/j.scitotenv.2014.01.033

Cited by 91 publications

(67 citation statements)

References 42 publications

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“…We suspected that the decrease in MeHg migration rates in leaves may also be attributed to the translocation of MeHg to the rice grains in harvest time. It has been reported that most MeHg accumulates in the rice grain compared to other rice plant tissues [32][33]. And MeHg in soil was first absorbed by roots and then transferred to the stem and leaf, and finally translocated to the grain during the harvest period [34].…”

Section: Migration Of Mehg In the Rice Plantsmentioning

confidence: 99%

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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Section: Migration Of Mehg In the Rice Plantsmentioning

confidence: 99%

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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“…Finally, it is possible that AWD-35 altered the availability of inorganic Hg for methylation. Concentrations of inorganic reactive Hg, an operationally defined fraction believed to be available for methylation, decreased in rice fields during flooded periods and increased when the soil was dried (Marvin-DiPasquale et al, 2014). Thus changes in Hg bioavailability due to AWD-35 would be expected to promote Hg(II) methylation.…”

Section: Soil Hg and Mehg Dynamicsmentioning

confidence: 99%

“…Wetland soils, including rice fields, are important sites of MeHg production (Gilmour et al, 1998;Krabbenhoft et al, 1995;Marvin-DiPasquale et al, 2014;Podar et al, 2015;Windham-Myers et al, 2014). Methylmercury produced in rice field soil is accumulated by rice plants more readily than inorganic Hg (Strickman and Mitchell, 2017;Zhang et al, 2010).…”

mentioning

confidence: 99%

“…Wet-dry cycles may enhance MeHg production by converting Hg to forms that are more easily methylated (Marvin-DiPasquale et al, 2014) and electron acceptors are regenerated when soil dries (Eckley et al, 2015;Marvin-DiPasquale et al, 2014;Singer et al, 2016). These increases in substrate availability can stimulate the activity of Hg(II)-methylating microbes, resulting in spikes of soil MeHg when dried soils were reflooded (Marvin-DiPasquale et al, 2009;Rothenberg and Feng, 2012).…”

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confidence: 99%

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Alternate Wetting and Drying Decreases Methylmercury in Flooded Rice (Oryza sativa) Systems

Tanner

Windham‐Myers

Marvin-DiPasquale

et al. 2018

Soil Science Soc of Amer J

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In flooded soils, including those found in rice (Oryza sativa L.) fields, microbes convert inorganic Hg to more toxic methylmercury (MeHg). Methylmercury is accumulated in rice grain, potentially affecting health. Methylmercury in rice field surface water can bioaccumulate in wildlife. We evaluated how introducing aerobic periods into an otherwise continuously flooded rice growing season affects MeHg dynamics. Conventional continuously flooded (CF) rice field water management was compared with alternate wetting and drying, where irrigation was stopped twice during the growing season, allowing soil to dry to 35% volumetric moisture content, at which point plots were reflooded ( Abbreviations: %Fe(II), ferrous iron as a percent of total citrate-dithionite extractable Fe; %MeHg, the percentage of total Hg that is methylmercury; AWD, alternate wetting and drying; AWD-35, alternate wetting and drying to 35% volumetric moisture content; CF, continuous flooding; DAP, day after planting; Fe(II) AE , acid-extractable ferrous Fe; (Fe(III) a, amorphous ferric iron; Fe T , total citrate-dithionite extractable Fe; FeRB, Fe-reducing bacteria; MeHg, methylmercury; SRB, sulfate-reducing bacteria; THg, total Mg. R ice is grown on 161 million ha worldwide and is the staple crop for 3.5 billion people globally (Muthayya et al., 2014). Rice is a semiaquatic plant and is usually grown under flooded conditions to help control weeds, increase nutrient availability, and ensure water supply during drought (Kendig et al., 2003). Flooded conditions also allow rice fields to serve as important wildlife habitat (Czech and Parsons, 2002); however, rice production is also associated with several negative impacts. First, rice requires higher water inputs than other cereal crops (Pimentel et al., 2004). Increasing food demand from a growing population and decreasing water availability (Mekonnen and Hoekstra, 2016) are placing pressure on rice growers to reduce the amount of water used for rice production. Second, the global warming potential of rice is elevated compared with other crops, caused in large part by high methane emissions (Linquist et al., 2012;Wassmann et al., 2010). Finally, flooded conditions can also change the speciation and increase the bioavailability of As and k. Christy Tanner* Core Ideas• We studied how alternate wetting and drying (AWd) water management effects methylmercury (MeHg) dynamics in rice fields.• Alternate wetting and drying reduced MeHg concentrations in soil, water, and rice grain.• Iron speciation indicated that AWd oxidized the soil and regenerated electron acceptors.• Rice yield did not differ between AWd and the control over 4 yr.

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“…Recently, many studies have clearly showed that rice can be another important pathway of MeHg exposure to inhabitants in higher Hg hotspots, such as Hg mining areas in Guizhou province [9,10]. Actually, the elevated Hg levels only occur in Hg mining areas, urban soil and surrounding region of coal combustion in China, which only covers approximate 800 km 2 and account for about 1% of Chinese cultivation area.…”

Section: Introductionmentioning

confidence: 99%

Methylmercury accumulation in rice plants (Oryza sativa L.) In low Hg areas and the potential health - Risk exposing in extreme micro-environments

Tang¹,

Fan²,

Mao³

et al. 2017

Adv Mater Sci

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Recent studies have clearly showed that rice can be another important pathway of MeHg exposure to inhabitants in higher Hg hotspots, such as Hg mining areas in Guizhou Province, China. However, the elevated Hg levels only account for about 1% of Chinese cultivation area and the majority of rice planting areas are ranked the low Hg areas. Therefore, it is important and necessary to verify MeHg accumulation in rice in low Hg areas because rice is the stable daily food in these extensive areas. Importantly, the human health-risk assessment of Hg exposure doesn't consider the extreme values observed. Although these extreme values are fewer, it may result in critical Hg exposure for local inhabitants and may become the determinants or "drivers" of environmental decisions and policies, even though most individuals are exposed to far lower concentrations and risks. This study clearly confirmed rice has the highest ability to accumulate MeHg not only in Hg mining areas also in low Hg areas. The THg and MeHg concentrations in the rice samples collected from northeast plain rice advantage area were lower than that of Xinyang city, and significantly lower than that of reported from the rice from southern China. However, in extreme micro-environments, routine consumption of rice provides a THg and MeHg intake of 11.6 µg kg -1 and 1.8 µg kg -1 of body weight per day, respectively. The MeHg intake was 18 times of RfD of USEPA and 7.8 times of PTWI by JECFA. It clearly demonstrates that a few inhabitants, such as Gouxi and Dashui in Wanshan, are exposed to Hg and MeHg to a much serious health risk.

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Mercury cycling in agricultural and managed wetlands: A synthesis of methylmercury production, hydrologic export, and bioaccumulation from an integrated field study

Cited by 91 publications

References 42 publications

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

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

Alternate Wetting and Drying Decreases Methylmercury in Flooded Rice (Oryza sativa) Systems

Methylmercury accumulation in rice plants (Oryza sativa L.) In low Hg areas and the potential health - Risk exposing in extreme micro-environments

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