This research group focuses on the dynamics of metals in the soil-plant interfaces, and the toxicological impacts of soil pollution on plants and soil microbes. Metals and metalloids under investigation in this group are lead, arsenic, cadmium and copper. Topics of research include: arsenic uptake by rice plants and rhizosphere processes, bioavailability of metals in soils, remediation of Pb contaminated soils, molecular toxicology of soil contamination, degradation and accumulation of organic pollutants in soil-plant systems. In the last two years, the following innovative achievements have been made:

Soil arsenic pollution control for paddy soil: Arsenic is an important pollutant in the environment, and many studies have shown that the foodchain transfer is one of the main pathways through which humans are exposed to arsenic contamination. For the countries with rice as the main food in the Southeast Asian region, the uptake and accumulation of arsenic in rice is a vital environmental issue relating to the human health. In China, due to the mining activities and geogenic factors (such as underground water pollution), large areas of soil arsenic pollution have occurred, which threatens seriously the local and regional food safety. In this project, rice was selected as the research object, this study centers on the role of iron plaque on the root surface of rice plants in sequestration of As, which may to potentially explored as novel way of controlling the accumulation of arsenic in rice. Results from this group further indicated that the formation of iron plaque on paddy rice root surface maybe related to the phosphate supply in the soil, thus it is first time to present a possible three-way interactions between iron plaque, phosphorous and arsenic during the uptake and accumulation by rice plants. These research results have been published in some famous academic journals including New Phytologist and Journal of Experimental Botany, furthermore New Phytologist has accepted one recent paper as a rapid report. The novel research results of this series attached more importance from the domestic and overseas academic community. Because of these research progress, the world-renowned journal Trends in Plant Science has published a commentary paper in its newly-released issue (9: 415-417, 2004), which says that: “A study by Yongguan Zhu and co-workers has added greatly to our understanding of arsenic dynamics in the rhizosphere of paddy rice. Their finding that arsenic is sequestered in iron plaque on root surfaces in plants, regulated by phosphorus status, and that there is considerable varietal variation in arsenic sequestration and subsequently plant uptake, offers a hope for breeding rice for the new arsenic disaster in South-East Asia –the contamination of paddy soils with arsenic.”

Remediation and risk assessment of the lead-contaminated soils: Lead may influence the human health through soil-plant systems and soil-human system, especially the health of children. This research was to utilize phosphorus-containing compounds to immobilize lead in the polluted soil and to reduce its uptake and accumulation of lead by vegetables. Through this study, the group also developed a multi-channel artificial stomach simulation system to investigate the bioaccessibility of lead in the soil. This system was then used to assess the effectiveness of phosphorus-containing compounds in reducing the bioaccessibility. Results from this series of research have been published in some journals including Environment International, and two Chinese invention patents have been applied.