Photochemically induced changes in bioavailable carbon and nitrogen pools in a boreal watershed

被引:74
作者
Bertilsson, S
Stepanauskas, R
Cuadros-Hansson, R
Granéli, W
Wikner, J
Tranvik, L
机构
[1] Uppsala Univ, Dept Limnol, S-75236 Uppsala, Sweden
[2] Linkoping Univ, Dept Water & Environm Studies, S-58183 Linkoping, Sweden
[3] Univ Lund, Dept Ecol, S-22362 Lund, Sweden
[4] Umea Marine Sci Ctr, S-90010 Umea, Sweden
关键词
UV radiation; DOC; DON; bacterial bioassays; carboxylic acids; ammonium;
D O I
10.3354/ame019047
中图分类号
Q14 [生态学(生物生态学)];
学科分类号
071012 ; 0713 ;
摘要
In several recent studies, a net stimulation of bacterial growth has been demonstrated after exposing humic surface waters to solar radiation or artificial ultraviolet radiation. This stimulation has been attributed to a photochemical release of bioavailable carbon or nitrogen compounds (ammonium). In a synoptic experiment, we exposed 0.2 mu m filtered water from 12 different habitats in a river system, dominated by allochthonous carbon input, to mild artificial UV radiation. A significant photochemical release of carboxylic acids of low molecular weight occurred. Furthermore, the exposure increased carbon-limited bacterial yield on average by a factor of 1.7. No photochemical production of free ammonium could be detected, which was in accordance with the lack of effects of radiation on bacterial growth yield under nitrogen-limited conditions. We conclude that, in boreal systems dominated by allochthonous carbon input, photochemical production of bioavailable carbon rather than nitrogen compounds is likely to positively influence the total substrate pool available for bacterial utilization.
引用
收藏
页码:47 / 56
页数:10
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