2010 GSA Denver Annual Meeting (31 October 3 November 2010)
Paper No. 40-21
Presentation Time: 8:00 AM-6:00 PM

OPTIMIZATION OF A COLORIMETRIC METHOD TO DETERMINE ARSENIC SPECIES AND PHOSPHATE IN SEA WATER

GODDARD, Coreyn1, ANCIRO, Stephanie2, and DHAR, Ratan1, (1) Geology Discipline, Earth and Physical Sciences, York College of City University of New York, 94-20 Guy R. Brewer Blvd, Jamaica, NY 11451, coreyn.goddard@yorkmail.cuny.edu, (2) Queens High School for the Sciences, York College of City University of New York, 94-50 159 Street, Jamaica, NY 11433

Arsenic is a very toxic semi-metal with the highest toxicity in its inorganic forms that, when ingested, can cause severe illnesses. Interest in the occurrence and quantity of arsenic in sea water has drawn scientific attention immediately after the BP oil spills in Gulf of Mexico recently. Scientists are increasingly concerned with the importance of studying the behavior of arsenic compounds in terms of their chemical species rather than total concentration. In this study, A colorimetric method was modified for simultaneous phosphate and inorganic arsenic species (AsIII & AsV) detection in low phosphate containing sea water. The method was initially developed for analyzing groundwater with high levels of phosphate and arsenic. The method is based on the formation of molybdo-arsenate and molybdo-phosphate in pre-treated and non-treated acidified (HCl to 1%) samples which give an apparently homogeneous blue color to the solution. The modification includes the optimization of different reagent strength and complete reaction time based on the kinetics of color development. The H+ concentration was also optimized in non-treated acidified aliquot for arsenic speciation. The optimized method is simple, inexpensive and reliable with the detection limit of 4 mg l-1. The optimized method was applied to determine inorganic arsenic species(As III and As V) and phosphate concentration brackish water in Jamaica Bay and Atlantic Ocean water in Western Long Island Sound, NY. Mean recovery obtained for a suite of sea water samples from Howard Beach area in Jamaica Bay spiked with 100 µg/L AsIII and 100 µg/L AsV were 99.7 ± 3.6% (n= 8) and 100 ± 4.6% (n=9) for total As and AsV respectively. The optimized method could be applied for solid phase arsenic speciation, which has a broader implication in arsenic contaminated areas around the world.

Funded by US Dept. of Education (USDOE) Grant titled "Enhancing African American Students' Talents."

2010 GSA Denver Annual Meeting (31 October 3 November 2010)
General Information for this Meeting
Session No. 40--Booth# 235
Participation of Undergraduates and K12 Students in Environmental and Geoscience-Related Research: A Critical Tool for Experiential Learning Technique (Posters)
Colorado Convention Center: Hall D
8:00 AM-6:00 PM, Sunday, 31 October 2010

Geological Society of America Abstracts with Programs, Vol. 42, No. 5, p. 120

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