TOXIC BIOPHILE ELEMENTS ARSENIC, LEAD, AND MERCURY: FROM PERSONAL TO PROFESSIONAL UNDERGRADUATE RESEARCH IN ENVIRONMENTAL GEOCHEMISTRY

Arsenic, lead, and mercury are classic toxic substances that have been widely dispersed throughout the hydrosphere, biosphere, and lithosphere by human activities since Roman times. These elements make interesting and important personal learning experiences for freshman students in physical geology and environmental science classes. Numerous senior level research projects can be directed toward site-specific research in As, Pb, and Hg. Annually until 2003 pressure treated wood containing thousands of tons of arsenic were dispersed across American yards in decks, fences, and play sets. After training in identification and measurement and calculation freshmen pick or are assigned an assessable structure made of pressure treated wood to determine its total arsenic content. Senior level arsenic projects in west Georgia are often focused on the decomposition of pressure treated wood and the displacement of arsenic into the soil and local biosphere. Human dispersion of lead into the biosphere, hydrosphere, and lithosphere peaked with an annual rate of several 100,000 tons of Pb in the early 1970s. Chief depressive methods were burning leaded gasoline, lead-based paints, lead solder, and lead-containing plumbing fixtures. Freshmen projects include a personal determination of their life-time exposure to lead that includes interviewing parents and others with a knowledge of their past living conditions. Senior projects are focused on ICP or Hach spectrometer measure of lead in paint and drinking water. Mercury, although it is the least abundant of these biophile elements, is above recommended levels in 8% of newborn babies in the USA. Freshmen projects include a semester long diary of fish consumption followed by a web-based calculation of the student’s mercury intake. One of our recent senior research projects is on the concentration of mercury in giant catfish in the rivers and lakes of Georgia and Alabama (Harris, Holloway, and Hollabaugh, 2004).