PM07 Pollutant Chemistry Transport, Cycling and Fate
Exhibit Hall
8:00 AM - Monday
(PM088) Screening of several medias for phosphorus sorption efficiency and strength.
White, S.1, Klaine, S.1, Taylor, M.1, Whitwell, T.2, 1 Clemson University, Clemson Institue of Environmental Toxicology, Pendleton, SC, USA2 Clemson University, Horticulture Department, Clemson, SC, USA
ABSTRACT- Hypereutrophication of receiving streams is an ecosystem stress commonly associated with nursery and greenhouse run-off. Phytoremediation is an effective way to reduce the amount of nutrients in nursery and greenhouse run-off water. Unfortunately phosphorus (P) does not appear to be efficiently removed from run-off water by plants alone. An alternative to plant uptake is to maximize P sorption to the soil/medium in wetlands used to treat nursery runoff. This study examined the effectiveness of greenhouse sand, vermiculite, three (3) peat based medias, and crushed brick to sorb P. We determined P sorption capacities and rates for the six media, as well as the P desorption rate of the medias. Solutions (25 mL) of 0.01 M CaCl2 containing of 0, 0.1, 1, 10, 100, and 1000 mg P⋅L-1 were added to 2 g of each media. The mixtures were shaken for 24 hours (h) at 25° C, centrifuged, and the supernatant filtered and analyzed on a spectrophotometer for P content. Sorption isotherms were plotted using both the Langmuir and Freundlich equations. Sorption rates were determined by incubating mixtures for 6, 12, 24, 36, 48, and 72 h to determine kinetic constants. Desorption studies involved incubating the soils in P solutions for the time period necessary for them to attain equilbrium. These samples were then placed in P free solution for 6, 12, 24, 48, and 72 h to determine kinetic constants. Results suggest that modifying the soil medium in constructed wetlands may result in higher P removal.
Key words: kinetics, desorption, isotherms, wetland