Determination of Mercury in Surface Waters Using an Optimized Cold Vapor Spectrophotometric Technique

Abstract

An analytical method to measure mercury in environmental samples was optimized based upon amalgamation of mercury on gold-coated sand and subsequent ultraviolet absorption measurement of the mercury vapor driven off the sand upon heating. Sample handling and storage methods were employed that were virtually free from mercury loss or contamination. Analytical procedures were tested on standard reference materials obtained from the USEPA and USGS and at concentration levels in the range anticipated for the environmental samples. Stream samples, collected over a seven-month period, were filtered (0.45 μm) in the field, and the mercury in dissolved and particulate fractions was determined. Dissolved mercury concentrations ranged from 24.1 ng/1 to 116.9ng/1 (N = 120) while particulate mercury concentrations ranged from 0.2 μg/g to 33.4 μg/g (N = 120). The method has been found useful for analyzing environmental samples and has been shown to be very sensitive and free of interferences.

Key Words:

• Mercury analysis
• water
• suspended sediments
• cold vapor