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Optical properties as tracers of riverine dissolved organic matter biodegradation in a headwater tributary of the Yangtze
Ni, Maofei1,2,3; Li, Siyue1
2020-03-01
摘要The optical properties can characterize the chemical composition, bioavailability and origins of dissolved organic matter (DOM), and thus indicate its biodegradability in natural waters. However, there remains a large gap in how DOM optical properties (UV-visible and fluorescence spectra) trace and predict the dissolved organic carbon biodegradation (%BDOC) in river systems. Over a 56-day laboratory incubation experiment, we examined the variations of %BDOC and DOM optical properties in a headwater tributary of the upper Yangtze River. We found that DOC biodegradability was significantly higher in the tributaries (20 degrees C: 38.9 +/- 19.8%; 30 degrees C: 58.6 +/- 19.5%) than that in the main stem (20 degrees C: 26.1 +/- 18.2%: 30 degrees C: 41.8 +/- 16.3%) (p < 0.001). The %BDOC, exhibiting coincident peaks in the agricultural regions and troughs in the ecologically fragile regions, increased by a factor of two-fold with a temperature gradient of 10 degrees C. The optical properties SUVA(254) and S-275(-295) decreased, while the S-350(-400), FI and BIX increased after the incubations, implying the synchronous biodegradation and production of young DOMs via microbial respiration. The %BDOC:DOC tightly linked to a(254), S-275(-295), S-350(-400) and BIX, illustrating that optical properties could predict the riverine %BDOC. The findings demonstrated that optical properties could be regarded as the useful tracers of DOM biodegradation in river systems.
关键词Optical properties Biodegradation Chemical compositions Fluorescence spectra UV-visible spectra
DOI10.1016/j.jhydrol.2019.124497
发表期刊JOURNAL OF HYDROLOGY
ISSN0022-1694
卷号582页码:7
通讯作者Li, Siyue(syli2006@163.com)
收录类别SCI
WOS记录号WOS:000517663700033
语种英语