It has been known for a long time that phytoremediation, the use of plants to remove contaminants from soils or estuaries, holds great promise for application to environmental remediation on a massive scale. At this time, however, the basic chemistries necessary to using such an approach are not well-developed, especially for trace element contaminants. We have been studying Se phytoremediation for several years using wild type and genetically modified Indian Mustard, Brassica juncea, a quick growing, high biomass plant that is a mid-level Se accumulator (up to ca. 1,000 ppm). The plant may volatilize, accumulate or exude the Se through its metabolic processes that interconvert various Se species, e.g. change the molecular level chemistry. Further through genetic modifications to obtain better phytoremediation results, the plant metabolism may be modified. We continue a high interest in unraveling this phytochemistry under various growth and plant conditions. (See publications and presentations).

 Gailer et al. state, “Among the most startling observations in mammalian toxicology is that a lethal dose of selenium can be overcome by an otherwise lethal dose of arsenic” (JACS, 2000, 122, 4637 – 4639). And so it is with other metals including Hg. However, while this “antagonism” has been studied in animals, there is still no satisfactory molecular level understanding of this well-known phenomena. In fact, Se/Hg antagonism may be demonstrated in by plants, perhaps by a similar molecular level mechanism as in animals. We have now the tools at our disposal to better understand this fascinating behavior. For example in several plant types we find that a high molecular weight complex of Hg/Se (perhaps protein associated), is sequestered in the plant roots. And while Se is translocated to the aerial portions of the plant, Hg is not. If then only the aerial portions are consumed, then there should be no concern about Hg contamination. However, it is necessary to study the chemistry of formation and decomposition of the “complex” to fully understand this type of antagonism and we look forward to adding in a major way to this understanding. (See publications and presentations).