Liu Yue, He Qiu-Fang, Liu Ning-Kun, Liu Jiu-Chan, Wang Zheng-Xiong, Duan Shi-Hui
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.
Huan Jing Ke Xue. 2018 Jun 8;39(6):2651-2660. doi: 10.13227/j.hjkx.201711106.
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 (<0.05) and 0.644 (<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.
由于抗性溶解有机物（RDOM）在岩溶碳汇（最重要的陆地碳汇之一）中起着至关重要的作用，因此聚焦于岩溶水系统中RDOM的起源、运移和转化的研究具有重要意义。目前，三维荧光激发-发射矩阵（3D-fluorescence EEMs）被用于检测发色溶解有机物（CDOM，RDOM的重要组成部分）的组成和来源。这是一种非常快速且高效的CDOM分析方法。在本研究中，三维荧光激发-发射矩阵结合紫外-可见吸收光谱被用于分析金佛山碧潭河中CDOM的组成和来源。于2017年1月至3月从9个采样点采集样品，并采用CDOM激发-发射矩阵和紫外-可见吸收光谱进行分析。此外，测定了水化学特征，然后用平行因子分析（PARAFAC）对样品进行分析以检测发色荧光基团和指标。PARAFAC分析揭示了三个发色荧光基团，其中富里酸是最大的组分，约占44%，腐殖酸含量约为32%，类酪氨酸含量约为24%。计算了四个指标：荧光指数（FI）、生物指数（BIX）、腐殖化指数（HIX）和β∶α，其平均值分别为2.06、0.87、4.35和0.69，表明FI、BIX和β∶α值相对较高，HIX值较低，这意味着CDOM是自生的，起源于旱季的微生物和水生植物。指标的空间动态变化显示，从上游区域到下游区域BIX增加，HIX降低，这意味着土地利用和人类活动的影响。森林土壤输入更多的腐殖酸，农业输入更多的氮和磷，导致水生植物和微生物大量繁殖。此外，溶解无机碳（DIC）与腐殖酸、类酪氨酸的相关系数分别为0.515（<0.05）和0.644（<0.01），由此可以推断DIC有助于CDOM的形成。本研究的结论表明，DIC将被岩溶水水生植物和微生物固定，然后作为自生CDOM沉降，成为岩溶水碳汇的一部分。
