Nature and abundance of organic radicals in natural organic matter:: Effect of pH and irradiation

被引:129
作者
Paul, Andrea
Stoesser, Reinhard
Zehl, Andrea
Zwirnmann, Elke
Vogt, Rolf D.
Steinberg, Christian E. W.
机构
[1] Leibniz Inst Freshwater Ecol & Inland Fisheries, D-12561 Berlin, Germany
[2] Humboldt Univ, Inst Chem, D-12489 Berlin, Germany
[3] Univ Oslo, Dept Chem, N-0315 Oslo, Norway
[4] Humboldt Univ, Inst Biol, D-12437 Berlin, Germany
关键词
D O I
10.1021/es060742d
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
Dissolved natural organic matter (NOM) plays an essential role in freshwater geochemical and biochemical processes. A major property, its redox behavior, can be attributed to the chinone building blocks, which can form stable radicals. However, electron paramagnetic resonance (EPR) data indicating free radicals on solid NOM are sparse. Here we present EPR spectra of 23 NOM from European surface waters isolated by reverse osmosis. The organic radical concentrations of NOM ranged from 5 x 10(15) to 1.84 x 10(17) spins g(-1), and g values ranged from 2.0031 to 2.0045. Number and type of organic radicals in solid NOM are significantly influenced by the pH of raw water. EPR experiments indicate the presence of semiquinone-type radicals in coexistence with carbon-centered '' aromatic '' radicals, with the semiquinone-type radicals dominating at alkaline pH. Basically these processes are reversible. Organic radical concentrations in NOM adjusted to pH 6.5 before freeze-drying correlate with iron and aluminum contents. UV- and VIS-irradiation of solid NOM can lead to more than a 10-fold increase of the concentration of organic radicals. These radicals were long-lived and had the same g value as the original radical. Similar effects were not observed with isolated humic and fulvic acids, demonstrating the limited reflection of environmental properties of organic carbon by the classical isolation procedure.
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页码:5897 / 5903
页数:7
相关论文
共 38 条
[1]   Effect of pH on the aggregation of a gray humic acid in colloidal and solid states [J].
Alvarez-Puebla, RA ;
Garrido, JJ .
CHEMOSPHERE, 2005, 59 (05) :659-667
[2]   COPPER-BINDING BY DISSOLVED ORGANIC-MATTER .1. SUWANNEE RIVER FULVIC-ACID EQUILIBRIA [J].
CABANISS, SE ;
SHUMAN, MS .
GEOCHIMICA ET COSMOCHIMICA ACTA, 1988, 52 (01) :185-193
[3]  
Chang Chien SW., 2003, INT J APPL SCI ENG, V1, P62
[4]  
Cooper W.J., 1988, ADV CHEM SER, V219, P333
[5]  
Dudarchik VM, 1997, COLLOID J+, V59, P287
[6]   Fluorescence and FT-IR spectroscopic studies of Suwannee river fulvic acid complexation with aluminum, terbium and calcium [J].
Elkins, KM ;
Nelson, DJ .
JOURNAL OF INORGANIC BIOCHEMISTRY, 2001, 87 (1-2) :81-96
[7]   Influence of Pb(II) on the radical properties of humic substances and model compounds [J].
Giannakopoulos, E ;
Christoforidis, KC ;
Tsipis, A ;
Jerzykiewicz, M ;
Deligiannakis, Y .
JOURNAL OF PHYSICAL CHEMISTRY A, 2005, 109 (10) :2223-2232
[8]   Natural organic matter in drinking water -: the "NOM-typing project", background and basic characteristics of original water samples and NOM isolates [J].
Gjessing, ET ;
Egeberg, PK ;
Håkedal, J .
ENVIRONMENT INTERNATIONAL, 1999, 25 (2-3) :145-159
[9]   SINGLET OXYGEN REACTIONS ON IRRADIATED SOIL SURFACES [J].
GOHRE, K ;
SCHOLL, R ;
MILLER, GC .
ENVIRONMENTAL SCIENCE & TECHNOLOGY, 1986, 20 (09) :934-938
[10]   EPR investigations of structure of humic acids from compost, soil, peat and soft brown coal upon oxidation and metal uptake [J].
Jezierski, S ;
Czechowski, F ;
Jerzykiewicz, M ;
Drozd, J .
APPLIED MAGNETIC RESONANCE, 2000, 18 (01) :127-136