【摘要】 基于2017年1—12月在抚仙湖开展的逐月观测,利用紫外—可见吸收光谱和三维荧光光谱技术探讨该湖有色可溶性有机物(CDOM)的来源组成及时空变化特征.12个月CDOM吸收值a(254)的均值为3.47±0.57 m-1,范围为1.82～5.22m-1,说明CDOM丰度较低.平行因子分析结果给出了2种类酪氨酸荧光组分(C1和C3)、1种类色氨酸荧光组分(C2)、1种类腐殖质荧光组分(C4),12个月内源组分(C1+C3)对总荧光强度的平均贡献为65.81%±15.38%,外源组分(C2+C4)的平均贡献为34.19%±15.38%;荧光指数FI的均值为1.73±0.14,腐殖化指数HIX的均值为1.02±0.37,生源化指数BIX的均值为1.23±0.27,说明CDOM主要为微生物内源产生.时空变化方面,春(3—5月)、夏(6—8月)、秋(9—11月)和冬(1、2、12月)季的a(254)分别为3.20±0.47、3.76±0.64、3.67±0.50和3.23±0.38 m-1,夏季和秋季均显著高于冬季和春季; CDOM丰度及内外源组分的空间分布具有季节异质性,可能与流域土地利用、河流输入、降雨、温度、光辐射等因素有关.更多还原

【Abstract】 Lakes are important in terrestrial carbon cycling. Source and optical composition of chromophoric dissolved organic matter(CDOM) in oligotrophic and deep lakes can display distinct properties,because of deep light penetration and long water residence time in these lakes. In this study,the optical properties and spatiotemporal distributions of CDOM were analyzed through monthly field investigation in 2017 in Lake Fuxian,an oligotrophic deep lake in Yunnan Province,China. The results showed that the average value of a(254) was 3.47±0.57 m-1,with the range of 1.82-5.22 m-1,indicating that CDOM abundance in the lake was relatively low compared with other mesotrophic and eutrophic lakes. Moreover,parallel factor analysis was performed to assess CDOM composition from excitation-emission matrix spectra and four components were identified: two tyrosine-like components(C1 and C3),one tryptophan-like component(C2) and one humic-like component(C4). The percentage of fluorescent intensity of C1+C3 was 65.81% ±15.38%,and the proportion of C2+C4 was 34.19% ±15.38%. The fluorescence index(FI),humification index(HIX) and biological/autochthonous index(BIX) was 1.73 ± 0.14,1.02 ± 0.37 and 1.23 ± 0.27,respectively. These results demonstrated that the CDOM was primarily originated from endogenous microbes in this lake. The average values of a(254) in spring(March-May),summer(June-August),autumn(September-November) and winter(January,February and December)were 3.20±0.47,3.76±0.64,3.67±0.50 and 3.23±0.38 m-1 respectively,with significantly higher values in summer and autumn than those in winter and spring. The abundance and spatial distributions of autochthonous and allochthonous CDOM exhibited seasonal heterogeneity,which might be correlated with land-use pattern,input of terrestrial materials,rainfall,water temperature and irradiance.更多还原