Nature of natural organic matter (NOM) in acidified and limed surface waters

被引:33
作者
Andersen, DO
Alberts, JJ
Takács, M
机构
[1] Agder Coll, N-4604 Kristiansand, Norway
[2] Univ Georgia, Inst Marine, Sapelo Island, GA 31327 USA
关键词
water; acidification; timing; natural organic matter; NOM; characterization;
D O I
10.1016/S0043-1354(99)00133-5
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
Natural organic matter (NOM) was isolated by reverse osmosis (RO) From the two inlet brooks and the outlet of Lake Terjevann with estimated recoveries of 85-90%. The lake has been receiving liming treatments since 1980 due to the acidic drainage from the catchments. Highperformance size exclusion chromatography (HPSEC) analyses of the RO samples and of ultrafiltered fractions indicate that there are five main size fractions of carbon dth molecular weights between 410-1170 Da in all three samples. However. the molecular weight distributions differ significantly in that the outlet sample have lower proportions of larger molecular weight NOM than do the inlets. Studies of spectral absorption coefficients at 154 nm support this molecular size distribution. Absorption coefficients of the samples at both 254 and 410 nm decrease with decreasing molecular weight so that the ratio E-2/E-4 increases with decreasing molecular weight, This trend appears independent of pH changes and especially effects the absorption coefficients of the higher molecular weight NOM. Studies of C:N ratios of the RO samples and of ultrafiltered fractions indicate that the outlet RO sample and that the lower molecular weight NOM are enriched in nitrogen. Supported by studies of spectral absorption coefficients and C:N ratios of the total RO samples and ultrafiltered fractions and effects of FH changes on the ultrafiltered fractions, it is hypothesized that in-lake processes are removing larger molecular weight NOM. This is possibly an effect of the timing which increase pH and calcium(II) concentrations in the lake water coinciding with hydrolysis and precipitation of aluminium(III) and iron(III). (C) 1999 Elsevier Science Ltd. All rights reserved.
引用
收藏
页码:266 / 278
页数:13
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