The impact of global warming on the uptake of arsenic into rice plants
Microbial Ecology and Applied Microbiology
Mineralogy, Petrology and Geochemistry
Final Report Abstract
Rice is the staple food worldwide. Unfortunately, global rice yield is already falling behind population growth. One reason for the decreased yields is the presence of toxic arsenic in many South(‐East) Asian paddy soils, which is known to decrease rice growth and productivity. The current change in Earth’s climate is causing land loss due to desertification and inundation, leading to lower (rice) crop yields and thus threatening global food security. According to the highest emission scenario for greenhouse gases presented in the 5th assessment report of the IPCC, global annual temperatures could rise by more than 5°C and atmospheric CO2 concentrations double by the year 2100. How increased temperatures and atmospheric CO2 affect arsenic mobility in paddy soil, and how this could ultimately affect the quality and production of rice, is unknown and was the main research question of this proposal. To answer this question, soil microcosms were incubated at today’s climate condition in rice paddies (33°C, 450 ppmv CO2) and the postulated climate of the year 2100 (38°C, 900 ppmv CO2). Control incubations were run at 33°C and 900 ppmv CO2 and at 38°C and 450 ppmv CO2 to differentiate between the effect of purely elevated CO2 or temperature. The fate of arsenic in the soil‐water‐ atmosphere continuum was evaluated and correlated to other geochemical parameters in the microcosms. The investigation showed that arsenic becomes more mobile in the pore water and that more arsenic is volatilized from the soil. These effects are temperature and CO2 dependent. The changes in arsenic mobility were related to other biogeochemical processes, for examples changes in iron and sulphur mobility in the pore water under the climate of 2100. Overall, the observed changes in geochemistry of the soil exposed to different climate conditions, suggests that significant changes in the soil microbial community occur that need to be tracked with sequencing approaches. It remains to be elucidated how climate change will affect the uptake of arsenic by rice when it is more mobile in the soil. We were engaged in scientific advise for the making of the ZDF’s Planet‐e documentary in Bangladesh und Vietnam: Arsen – der schleichende Tod.
Publications
- Goldschmidt Conference 2016, Yokohama, Japan. Impact of climate change on the dynamics of arsenic in paddy soils
E. Marie Muehe and Scott Fendorf
