scholarly journals Analysis of the Three-Dimensional Fluorescence Spectroscopy Characteristics of Dissolved Organic Matter in Groundwater from a Subtropical Cave in Dry Season—Daxiao Cave in South China Karst

Water ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 3574
Author(s):  
Renkai Zhang ◽  
Ziqi Liu ◽  
Kangning Xiong ◽  
Xiaoxi Lyu ◽  
Chenpeng Hu ◽  
...  

Groups in dissolved organic matter (DOM) emit fluorescence information at characteristic wavelengths when irradiated by excitation waves, which can reveal the geochemical behavior of dissolved organic matter in the environment and its sources, but there are few relevant studies in cave groundwater systems. In order to investigate the relationship between drip hydrochemistry characteristics and DOM in cave systems after subsurface leakage, in this study, from the perspective of dissolved organic matter in the karst cave water system, the groundwater in the dry season of Daxiao Cave was selected as the research object. Five drip points and one water pool (DX-1, DX-2, DX-3, DX-4, DX-5, and DX-C) in Daxiao Cave were monitored and consecutively sampled for four months. The parallel factor analysis method (PARAFAC), three-dimensional (3D) fluorescence parameters, and excitation-emission matrix fluorescence spectroscopy (EEM), combined with the hydrochemistry characteristics of the drip water and correlation analysis, were used to analyze the 3D fluorescence spectral characteristics of the DOM of the drip water of Daxiao Cave and their influencing factors. The results show that (1) the hydrochemistry type of the drip water in Daxiao Cave was within the Ca–Mg–HCO3 type, and Ca2+, Mg2+, and HCO3- were the dominant ions in Daxiao Cave; (2) the fluorescence fractions of drip water in dry season caves were dominated by C1 (humus-like), C2 (tryptophan-like), and C3 (tyrosine-like), and the fluorescence fractions of drip water DOM were controlled by protein fluorophores; (3) the DOM in the drip water of Daxiao Cave in the dry season was controlled in part by subsurface leakage and was largely the result of microbial degradation; and (4) the DOM of the drip water may be influenced by the chemical composition of the water, but the exact process is not clear.

Pedosphere ◽  
2017 ◽  
Vol 27 (5) ◽  
pp. 968-973 ◽  
Author(s):  
Wenming XIE ◽  
Shanshan ZHANG ◽  
Lin RUAN ◽  
Mingyue YANG ◽  
Weiming SHI ◽  
...  

2011 ◽  
Vol 356-360 ◽  
pp. 2536-2541 ◽  
Author(s):  
Li Min Zou ◽  
Jian Hua Li ◽  
De Gang Jiang ◽  
Yu Lai Wang

The indoor experimental study was on a large common species of filamentous green algae in the North Lake beach of Chongming Island - bristles algae liquid produced by algae growth during the photodegradation of colored dissolved organic matter (CDOM) spectral characteristics change. Absorption coefficient a (355) in the degradation experiment was reduced 27.44% , however , in the control experiment , a (355) was only 1.61% lower. In the photodegradation process of degradation experiments and control experiments, the values of M and S were increased to the different extent and the increased value of the former was higher than the latter. By using three-dimensional fluorescence spectroscopy (EEMS), the detected peak value of protein-and humic fluorescence in control experiments was little changed, while significantly increased in the degradation experiments. By the analysis of parallel factor model (PARAFAC) combined with three-dimensional fluorescence excitation - emission matrix data (EEMS), the three-component CDOM: C1, C2, C3, respectively were relative to humic fluorescence peaks A, C, and protein-like fluorescence B. In the degradation experiments, small changes were in the components of C1, however the components of C2, C3 compared with those in the control group were increased by nearly 2 times. All results showed that the photodegradation process of bristles algae liquid can cause changes of the CDOM in the structure and content, easier to produce small molecules and weak aromatic CDOM.


Author(s):  
Jeonghyun Kim ◽  
Yeseul Kim ◽  
Sung Eun Park ◽  
Tae-Hoon Kim ◽  
Bong-Guk Kim ◽  
...  

AbstractIn Jeju Island, multiple land-based aquafarms were fully operational along most coastal region. However, the effect of effluent on distribution and behaviours of dissolved organic matter (DOM) in the coastal water are still unknown. To decipher characteristics of organic pollution, we compared physicochemical parameters with spectral optical properties near the coastal aquafarms in Jeju Island. Absorption spectra were measured to calculate the absorption coefficient, spectral slope coefficient, and specific UV absorbance. Fluorescent DOM was analysed using fluorescence spectroscopy coupled with parallel factor analysis. Dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) were measured using high-temperature catalytic oxidation. The DOC concentration near the discharge outlet was twice higher than that in natural groundwater, and the TDN concentration exponentially increased close to the outlet. These distribution patterns indicate that aquafarms are a significant source of DOM. Herein, principal component analysis was applied to categorise the DOM origins. There were two distinct groups, namely, aquaculture activity for TDN with humic-like and high molecular weights DOM (PC1: 48.1%) and natural biological activity in the coastal water for DOC enrichment and protein-like DOM (PC2: 18.8%). We conclude that the aquafarms significantly discharge organic nitrogen pollutants and provoke in situ production of organic carbon. Furthermore, these findings indicate the potential of optical techniques for the efficient monitoring of anthropogenic organic pollutants from aquafarms worldwide.


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