典型喀斯特城市湖库溶解性有机质成分特征及来源解析

Dissolved Organic Matter Component and Source Characteristics of the Metropolitan Lakes and Reservoirs in a Typical Karst Region

为探索喀斯特城市湖库溶解性有机质(DOM)成分特征及来源信息,以我国贵阳市重要喀斯特湖库——红枫湖、百花湖、松柏山水库和阿哈水库为研究对象,分析了表层水体溶解性有机碳(DOC)、叶绿素a(Chla)和DOM光学参数(a_(254)、a_(280)、a_(350)、E2∶E3、S_(275-295)、FI、β:α、BIX、HIX)的空间差异,同时利用荧光吸收峰(B、T、A、M、C、D、N)和三维荧光平行因子分析(EEM-PARAFAC)解释DOM各成分丰度及占比状况,并运用Spearman相关分析及主成分分析(PCA)揭示DOM参数的相关性和主要环境过程.结果表明,喀斯特城市湖库ρ(DOC)和ρ(Chla)范围分别为4.24~11.9 mg·L^(-1)和0.32~19.7μg·L^(-1),松柏山水库腐殖质(a_(254))和芳香类蛋白质(a_(280))较高,导致相对分子质量(E2∶E3和S_(275-295))高于其它湖库.表层水体DOM成分主要包括可见光范围腐殖质和陆源富里酸,其占比分别为23.8%~46.9%和17.6%~28.4%.湖库荧光参数FI、β∶α和BIX较高而HIX较低,说明内源新生成分对DOM具有显著贡献.光学成分与来源参数具有显著的相关关系,喀斯特城市湖库DOM主要包括大分子腐殖质输入、小分子内源输入和碳酸盐耦合光合作用促进新生DOM等过程.

In order to explore dissolved organic matter(DOM)components and their origins in metropolitan lakes and reservoirs in the karst region,the typical Hongfeng Lake,Baihua Lake,Songbaishan Reservoir,and Aha Reservoir were investigated in Guiyang City.Surface water parameters,including dissolved organic carbon(DOC),chlorophyll a(Chla),and optical parameters(a_(254),a_(280),a_(350),E2∶E3,S_(275-295),FI,β∶α,BIX,and HIX)were analyzed.Fluorescence peaks(B,T,A,M,C,D,and N)and three-dimensional matrix fluorescence with parallel factor analysis(EEM-PARAFAC)were employed to explain distinct DOM abundances and proportions.Meanwhile,Spearman’s correlation coefficients and principal component analysis(PCA)were used to decipher parameter types and primary environmental processes.The results showed that aquaticρ(DOC)andρ(Chla)ranged between 4.24-11.9 mg·L^(-1)and 0.32-19.7μg·L^(-1),respectively.High humic-like(a_(254))and protein DOM(a_(280))were observed in the Songbaishan Reservoir,resulting in higher DOM molecular weight when compared to that in other lakes and reservoirs.Surface water DOM mainly contained visible-light humic-like(23.8%-46.9%)and terrestrial fulvic-like components(17.6%-28.4%).High FI,β∶α,and BIX but low HIX values in this study suggested that endogenous inputs largely contributed to aquatic DOM.Aquatic DOM component and source characteristics were significantly correlated with each other.Furthermore,inputs of humic-like DOM and microbial metabolism,as well as coupled carbonate dissolution and photosynthesis,drove dynamic DOM behaviors in the karst lakes and reservoirs.