Accumulation of total mercury and methylmercury in rice plants collected from different mining areas in China

Abstract

a b s t r a c tA total of 155 rice plants were collected from ten mining areas in three provinces of China (Hunan, Guizhou and Guangdong), where most of mercury (Hg) mining takes place in China. During the harvest season, whole rice plants were sampled and divided into root, stalk & leaf, husk and seed (brown rice), together with soil from root zone. Although the degree of Hg contamination varied significantly among different mining areas, rice seed showed the highest ability for methylmercury (MeHg) accumulation. Both concentrations of total mercury (THg) and MeHg in rice plants were significantly correlated with Hg levels in soil, indicating soil is still an important source for both inorganic mercury (IHg) and MeHg in rice plants. The obvious discrepancy between the distribution patterns of THg and MeHg reflected different pathways of IHg and MeHg accumulation. Water soluble Hg may play more important role in MeHg accumulation in rice plants.

Growing Rice Aerobically Markedly Decreases Mercury Accumulation by Reducing Both Hg Bioavailability and the Production of MeHg

“…1,40 In our study, the sum of the water-soluble fraction and the "human stomach acid"-soluble fraction were considered to be the "bioavailable inorganic Hg". 32,33 Our data suggested that the "bioavailable inorganic Hg" accounted for 0.02−0.18% of the THg amount in soil. This is in agreement with the previous findings, 41 because Hg is usually not present in the form of water-soluble ionic species in the aqueous phase but as species bound to organic matter (without a Hg−carbon bond) or suspended mineral particles.…”

“…By comparison with CF, the CA treatment decreased MeHg concentrations in rhizosphere soil by 38% and 44% under both glasshouse and paddy field conditions, respectively. The "bioavailable inorganic Hg" was defined as the sum of water-soluble Hg and "human stomach acid" soluble Hg: 33 these two fractions accounted for 0.02−0.18% of the THg content of the soil. The CA treatment greatly decreased the "bioavailable inorganic Hg" concentration by 45−56%, compared to the CF treatment (Table S3, Supporting Information).…”

“…Within the five fractions, only two (water-soluble and "human stomach acid"-soluble) represented the "bioavailable inorganic Hg". 33 The detection limits of this method were 0.001 mg L −1 for THg and Hg bioavailability, and 0.002 ng L −1…”

Mercury in alpine fish from four rivers in the Tibetan Plateau

“…For MeHg analysis, alkaline extraction was applied (Meng et al, 2014(Meng et al, , 2015. About 0.1 g of sample was weighed into an 8-mL brown glass bottle and 4 mL 25% (M/V) KOH/CH 3 OH solution was added.…”

Influence of rice straw amendment on mercury methylation and nitrification in paddy soils

“…The production of neurotoxic methylmercury (MeHg) by anaerobic microbes in paddy fields has raised widespread concern due to its uptake and accumulation by rice (Liu et al, 2014a;Meng et al, 2014;Rothenberg et al, 2014;Zhang et al, 2010). The recent identification of mercury (Hg) methylating hgcAB genes provides a foundation for evaluating microbial Hg-methylation potential in the environment (Parks et al, 2013;Gilmour et al, 2013).…”