MP7 Advances in Analysis and Measurements
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() Use of an Equilibrium–Based Sampler for Determining Free Ion Metal Concentrations in Environmental Samples.
Lewis, C.1, Griscom, S.1, Senn, D. 1, Shine, J.1, 1 Harvard School of Public Health, Boston, MA, USA
ABSTRACT- An understanding of metal speciation is crucial for assessment of the bioavailability and toxicity of metals in the environment. An equilibrium–based sampler for the determination of free ion Cu in aquatic systems (the 'Gellyfish') has been developed to determine free ion concentrations of Cu in both laboratory and field situations. Compared with other speciation techniques such as ASV and CLE–SE, the 'Gellyfish' sampler is inexpensive and not labor intensive. In addition to laboratory experiments with copper alone, the 'Gellyfish' sampler has also demonstrated the ability to determine free ion concentrations of Cu in solutions of multiple competing metals. A field–deployable version of the 'Gellyfish' has also been developed, employing a plastic housing used in DGT sampling devices with a 0.4 micron membrane protective filter. The devices were deployed in Boston Harbor and results evaluated for their potential to determine free ion concentrations in the field. Ambient free ion Cu concentrations measured by the 'Gellyfish' sampler in Boston Harbor were validated by simultaneously taking water samples and analyzing them via CLE–SE. Collective laboratory and field–based results suggest that the 'Gellyfish' may also be used to measure the free ion concentrations of other divalent metals such as Cd, Zn, and Pb. This equilibrium–based free ion sampler shows promise not only as a metal speciation tool but also for use in biomonitoring programs as a biomimic for metal uptake.
Key words: passive sampler, metal speciation, boston harbor