Use of biochar to reduce mercury accumulation in Oryza sativa L: A trial for sustainable management of historically polluted farmlands | JoVE Visualize

Use of biochar to reduce mercury accumulation in Oryza sativa L: A trial for sustainable management of historically polluted farmlands

Yi Man¹, Bo Wang¹, Jianxu Wang²

¹State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.

Environment International|March 30, 2021

View abstract on PubMed

Summary

Rice hull biochar (RHB) and wheat-rice straw biochar (RWB) reduce methylmercury (MeHg) in rice grains. These biochar amendments effectively lower probable daily intake (PDI) of MeHg, offering a sustainable solution for mercury-polluted soils.

Area of Science:

Environmental Science
Soil Science
Agricultural Science

Background:

Mercury (Hg) contamination in rice poses a significant risk to human health due to methylmercury (MeHg) accumulation.
Reducing the probable daily intake (PDI) of MeHg through rice consumption is crucial for public health.
Environmental-friendly amendments are needed to mitigate Hg contamination in agricultural soils.

Purpose of the Study:

To investigate the impact of rice hull-derived biochar (RHB) and wheat-rice straw-derived biochar (RWB) on mercury (Hg) and methylmercury (MeHg) in Hg-polluted soil and rice.
To assess the effectiveness of biochar amendments in reducing Hg phytoavailability and uptake by rice plants.
To evaluate the potential of biochar in lowering the probable daily intake (PDI) of MeHg from rice consumption.

Main Methods:

Field study using Hg-polluted soil from a mining area.
Application of different doses (0.6% and 3%) of RHB and RWB.
Analysis of total mercury (THg) and methylmercury (MeHg) fractionation, phytoavailability, and plant uptake.
Measurement of rice biomass and estimation of PDI of MeHg.

Main Results:

Both RHB and RWB significantly increased rice biomass and reduced bioavailable Hg concentrations in the soil.
RHB application decreased soil MeHg, while RWB (at 3%) increased it, potentially due to altered microbial communities.
Both biochar types significantly reduced MeHg concentrations in rice grains by 55-85%, lowering PDI below the reference dose.

Conclusions:

RHB and RWB are effective in reducing MeHg accumulation in rice grains.
Biochar amendments offer a sustainable strategy for managing Hg-polluted soils and mitigating dietary MeHg exposure.
Further research into RWB's effect on soil methylation is warranted, but both show promise for reducing human health risks.