IN THE SPOTLIGHT - Dr. Weihua Zhang

Arsenic Has Met Its Match!

Arsenic is widely publicized as one of most widely known and potent poisons on Earth today. Unfortunately, what isn’t as widely known is that arsenic contamination in drinking water has caused significant environmental problems around the world. In Bangladesh alone, millions of people were exposed to high levels of arsenic (the largest poisoning of a population in history) when arsenic contaminated groundwater sources, and ultimately found its way into the drinking water. Chronic arsenic exposure will cause cancers of the lung, bladder and skin. 

Chinese brake fern (Pteris vittata), the first reported arsenic hyperaccumulator, can efficiently remove arsenic from soils, even at low levels. Most of the arsenic mass is accumulated in its leaflets, at levels of up to 23,000 parts per million.  The scientific and environmental impact this brings is that this plant may potentially be used to clean up arsenic in the environment. However, despite research by several groups throughout the U.S., U.K. and elsewhere, the mechanism for arsenic hyper-accumulation in this plant is still unclear. Dr. Weihua Zhang, who recently joined FIU’s Applied Research Center as a researcher and Analytical Lab Manager, together with Dr. Yong Cai (Department of Chemistry and Southeast Environmental Research Center), Dr. Kelsey Downum (Department of Biological Sciences), and Dr. Leonard Scinto (Southeast Environmental Research Center) of Florida International University, as well as Dr. Lena Ma of the University of Florida, have been conducting research that may help in answering this question. This research was supported by two grants from the National Science Foundation awarded to Ma, Cai, and Downum in year 2000 and 2001.

It was noted by Dr. Zhang, that plants take up arsenate via phosphate uptake systems because of their chemical similarity, so does the Chinese brake fern. In normal plants, phosphate uptake systems prefer to take up phosphate rather than arsenate, and the phosphate uptake rate is 20 times higher than arsenate. However, Chinese brake fern almost lost this preference. Abnormal phosphate uptake systems in Chinese brake fern would explain why this plant can efficiently take up and accumulate arsenic.

According to Zhang, this study provided useful information for understanding why and how the Chinese brake fern has evolved to possess arsenic hyper-accumulation capability. In addition, this research showed that Chinese brake fern can efficiently take up both arsenate and arsenite. This could also be an important contribution to science, because direct removal of arsenite is a challenge for many currently applied arsenic decontamination techniques, and the knowledge generated from this research will be helpful for the brake fern’s proposed application. And, for those who have been directly affected with arsenic contaminated drinking water like Bangladesh, it may prove beneficial to the health of millions of people throughout the world. 

This study, as a part of Dr. Zhang’s dissertation research, was completed in FIU’s Department of Chemistry and Biochemistry under the supervision of Dr. Cai.