An evaluation of freezing as a preservation technique for analyzing dissolved organic C, N and P in surface water samplesAuthor(s): Jason B. Fellman; David V. D'Amore; Eran Hood
Source: Science of the Total Environment DOI: 10.1016/j.scitotenv.2007.11.027
Publication Series: Scientific Journal (JRNL)
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Techniques for preserving surface water samples are recently in demand because of the increased interest in quantifying dissolved organic matter (DOM) in surface waters and the frequent collection of samples in remote locations. Freezing is a common technique employed by many researchers for preserving surface water samples; however, there has been little evaluation of the effects of freezing on DOM concentrations. Ten streams were sampled in southeast Alaska with a range of dissolved organic carbon (DOC) concentrations to evaluate the influence of freezing (flash and standard freeze) and filter pore size on dissolved organic C, N, and P concentrations. We report a significant decrease in DOC (p<0.005) and total dissolved P (p<0.005) concentrations when streamwater samples were frozen, whereas concentrations of dissolved organic N did not significantly decrease after freezing (p = 0.06). We further show that when surface water samples were frozen, there was a decrease in the specific ultraviolet absorbance (SUVA) of DOC that is particularly evident with high concentrations of DOC. This finding suggests that spectroscopic properties of DOC have the potential to be used as indicators of whether surface water samples can be frozen. Our results lead us to recommend that surface water samples with high DOC concentrations and/or samples with high SUVA values should be analyzed immediately and not frozen.
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CitationFellman, Jason B.; D'Amore, David V.; Hood, Eran. 2008. An evaluation of freezing as a preservation technique for analyzing dissolved organic C, N and P in surface water samples. Science of the Total Environment. 392:305-312.
KeywordsDissolved organic carbon, freezing, stream chemistry
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