Student/presenter: Danira Garcia Gutierrez, B.S., Soil Science
Format: Poster presentation
Title: Exploring the Physicochemical Properties of Arsenic in Water Filtration Waste from Northwestern Costa Rica
Danira Garcia Gutierrez, AmandaJo Zimmerman, Matthew Siebecker
Arsenic (As), a known carcinogen, is present in drinking water in Northwestern Costa Rica. Filters are used to remove the arsenic, and the filtrate wastes are deposited on local soils. The filtrate waste is composed of anatase (TiO2) and contains arsenic (As) in high concentrations (400-600 mg kg-1). The introduction of this contaminant to the environment poses a potential threat to the food chain and the local community. The high wind environment of the region increases the mobility and inhalation risk of the contaminated soils. Little is known about the behavior of the As contaminated filtration waste, as there is little literature about the topic. This research will explore the concentration of As in the soil as well as its physicochemical properties such as mobility, morphology, behavior in anaerobic conditions, and desorption of As from the TiO2 filtration waste. To accomplish this, portable X-ray fluorescence spectrometry (PXRF), Xray absorption near edge structure (XANES), API Aerosizer, inductively coupled plasma optical emission spectroscopy (ICP-OES), and an anaerobic chamber were used. The PXRF data indicated the soil has 400-600 mg kg-1 of As, 254-636 mg kg-1 of vanadium (V), and 106,00-338,000 ppm of titanium (Ti). XANES was used to determine the species of As to be arsenate (As(V)). Analysis of particle size revealed an average particle diameter of less than one micron, which further increases the mobility and inhalation risk of nearby residents. The anaerobic behavior experiments were designed to test for As release and reduction. Desorption studies indicate the As is possibly associated with the inner and outer spheres of the TiO2 filtration waste, but this will be confirmed with future EXAFS analysis.