| Autor: |
Liu Y; Chongqing Key Laboratory of Karst Environment, School of Geographical Sciences, Southwest University, Chongqing 400715, China., He QF; Chongqing Key Laboratory of Karst Environment, School of Geographical Sciences, Southwest University, Chongqing 400715, China.; Key Laboratory of Karst Dynamics, Ministry of Land and Resource & Guangxi, Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004, China., Liu NK; Chongqing Key Laboratory of Karst Environment, School of Geographical Sciences, Southwest University, Chongqing 400715, China., Liu JC; Chongqing Key Laboratory of Karst Environment, School of Geographical Sciences, Southwest University, Chongqing 400715, China., Wang ZX; Chongqing Key Laboratory of Karst Environment, School of Geographical Sciences, Southwest University, Chongqing 400715, China., Duan SH; Chongqing Key Laboratory of Karst Environment, School of Geographical Sciences, Southwest University, Chongqing 400715, China. |
| Abstrakt: |
Since resistant dissolved organic matter (RDOM) plays a critically important role in a karst carbon sink, one of the most important continental carbon sinks, research focusing on the origination, transportation, and translation of RDOM in a karst water system is important. Currently, 3D-fluorescence EEMs are used to detect the composition and origination of chromophoric dissolved organic matter (CDOM), an important part of RDOM. This is a very fast and efficient method for CDOM analysis. In this study, 3D-fluorencence EEMs combined with UV-visible absorption spectrum were used to analyze the composition and origination of CDOM in the Bitan River at Jinfo Mountain. Samples were collected from nine sampling sites from January to March 2017 and analyzed with CDOM EEMs and UV-visible absorption spectrums. In addition hydrochemical characteristics were determined and then samples were stimulated with PARAFAC to detect the chromophoric fluorescent groups and indexes. The PARAFAC stimulation revealed three chromophoric fluorescent groups in which fulvic acid was the largest component, accounting for about 44%, with a humic acid content of about 32% and tyrosine-like acid content of about 24%. Four indexes: FI, BIX, HIX, and β∶α, were calculated, and the mean values were 2.06, 0.87, 4.35 and 0.69, which showed relatively high FI, BIX, and β∶α values and a low HIX value, implying that the CDOM was autochthonous and originated from microbes and aquatic plants in the dry season. The spatial dynamic of the index revealed an increased BIX and decreased HIX from the upstream area to the downstream area, implying the impact of land-use and human activities. The forest soil input more humic acid and agriculture input more N and P resulting in flourishing aquatic plants and microbes. Moreover, the correlation coefficients of DIC and humic acid, tyrosine-like acid were 0.515 ( P <0.05) and 0.644 ( P <0.01), from which it could be inferred that DIC contributed to CDOM formation. The conclusions of this study revealed that DIC would be fixed by karst water aquatic plants and microbes and then sink as autochthonous CDOM and become part of karst water carbon sink. |
