| YI Yueyuan,ZHENG Airong,GUO Weidong,YANG Liyang,CHEN Ding. 2014. Optical properties of estuarine dissolved organic matter isolated using cross-flow ultrafiltration. Acta Oceanologica Sinica, 33(4):22－29 |
| Optical properties of estuarine dissolved organic matter isolated using cross-flow ultrafiltration |
| Optical properties of estuarine dissolved organic matter isolated using cross-flow ultrafiltration |
| Received:November 14, 2012 Revised:January 07, 2013 |
| DOI：10.1007/s13131-014-0451-4 |
| Key words:colloidal organic matter three-dimensional fluorescence spectroscopy parallel factor analysis ultrafiltration Jiulong River Estuary |
| 中文关键词: colloidal organic matter three-dimensional fluorescence spectroscopy parallel factor analysis ultrafiltration Jiulong River Estuary |
| 基金项目:The National Natural Science Foundation of China under contract No. 41276064; the Chinese Scholarship Council Program and the Program for New Century Excellent Talents (NCET) to Weidong Guo; the Fundamental Research Funds for the Central Universities under contract No. 201112G011. |
| Author Name | Affiliation | E-mail | | YI Yueyuan | State Key Laboratory of Marine Environment Science, Xiamen University, Xiamen 361005, China
College of Ocean and Earth Sciences, Xiamen University, Xiamen 361005, China | | | ZHENG Airong | College of Ocean and Earth Sciences, Xiamen University, Xiamen 361005, China | | | GUO Weidong | State Key Laboratory of Marine Environment Science, Xiamen University, Xiamen 361005, China
College of Ocean and Earth Sciences, Xiamen University, Xiamen 361005, China | wdguo@xmu.edu.cn | | YANG Liyang | State Key Laboratory of Marine Environment Science, Xiamen University, Xiamen 361005, China | | | CHEN Ding | College of Ocean and Earth Sciences, Xiamen University, Xiamen 361005, China | |
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| Abstract: |
| Dissolved organic matter (DOM) from freshwater, mid-salinity, and seawater endmember samples in the Jiulong River Estuary, China were fractionated using cross-flow ultrafiltration with a 10-kDa membrane. The colloidal organic matter (COM; 10 kDa-0.22 μm) retentate, low molecular weight (LMW) DOM (<10 kDa) permeate, and bulk samples were analyzed using absorption spectroscopy and three-dimensional fluorescence excitation-emission-matrix spectroscopy. The UV-visible spectra of COM were very similar to those obtained for permeate and bulk samples, decreasing monotonically with increasing wavelength. Most of the chromophoric DOM (CDOM, expressed as the absorption coefficient a355) occurred in the LMW fraction, while the percentage of CDOM in the colloidal fraction was substantially higher in the freshwater endmember (13.4% of the total) than in the seawater endmember (6.8%). The bulk CDOM showed a conservative mixing behavior in the estuary, while there was removal of the COM fraction and a concurrent addition of the permeate fraction in the mid-salinity sample, implying that part of the colloidal CDOM was transformed into LMW CDOM. Two humic-like components (C1: <250, 325/402 nm; and C2: 265, 360/458 nm) and one protein-like component (C3: 275/334 nm) were identified using parallel factor analysis. The contributions of the C1, C2, and C3 components of the COM fraction to the bulk sample were 2.5%-8.7%, 4.8%-12.6%, and 7.4%-14.7%, respectively, revealing that fluorescent DOM occurred mainly in the LMW fraction in the Jiulong River Estuary. The C1 and C2 components in the retentate and permeate samples showed conservative mixing behavior, but the intensity ratio of C2/C1 was higher in the retentate than in the permeate fractions for all salinity samples, showing that the humic component was more enriched in the COM than the fulvic component. The intensity ratio of C3/(C1+C2) was much higher in the retentate than in the permeate fraction for mid-salinity and seawater samples, revealing that the protein-like component was relatively more enriched in COM than the humic-like component. The contribution of the protein-like component (C3) to the total fluorescence in the retentate increased from 14% in the freshwater endmember to 72% for the seawater endmember samples, clearly indicating the variation of dominance by the humic-like component compared to the protein-like component during the estuarine mixing process of COM. |
| 中文摘要: |
| Dissolved organic matter (DOM) from freshwater, mid-salinity, and seawater endmember samples in the Jiulong River Estuary, China were fractionated using cross-flow ultrafiltration with a 10-kDa membrane. The colloidal organic matter (COM; 10 kDa-0.22 μm) retentate, low molecular weight (LMW) DOM (<10 kDa) permeate, and bulk samples were analyzed using absorption spectroscopy and three-dimensional fluorescence excitation-emission-matrix spectroscopy. The UV-visible spectra of COM were very similar to those obtained for permeate and bulk samples, decreasing monotonically with increasing wavelength. Most of the chromophoric DOM (CDOM, expressed as the absorption coefficient a355) occurred in the LMW fraction, while the percentage of CDOM in the colloidal fraction was substantially higher in the freshwater endmember (13.4% of the total) than in the seawater endmember (6.8%). The bulk CDOM showed a conservative mixing behavior in the estuary, while there was removal of the COM fraction and a concurrent addition of the permeate fraction in the mid-salinity sample, implying that part of the colloidal CDOM was transformed into LMW CDOM. Two humic-like components (C1: <250, 325/402 nm; and C2: 265, 360/458 nm) and one protein-like component (C3: 275/334 nm) were identified using parallel factor analysis. The contributions of the C1, C2, and C3 components of the COM fraction to the bulk sample were 2.5%-8.7%, 4.8%-12.6%, and 7.4%-14.7%, respectively, revealing that fluorescent DOM occurred mainly in the LMW fraction in the Jiulong River Estuary. The C1 and C2 components in the retentate and permeate samples showed conservative mixing behavior, but the intensity ratio of C2/C1 was higher in the retentate than in the permeate fractions for all salinity samples, showing that the humic component was more enriched in the COM than the fulvic component. The intensity ratio of C3/(C1+C2) was much higher in the retentate than in the permeate fraction for mid-salinity and seawater samples, revealing that the protein-like component was relatively more enriched in COM than the humic-like component. The contribution of the protein-like component (C3) to the total fluorescence in the retentate increased from 14% in the freshwater endmember to 72% for the seawater endmember samples, clearly indicating the variation of dominance by the humic-like component compared to the protein-like component during the estuarine mixing process of COM. |
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