摘要
千岛湖水质优良,具有较低的初级生产力和较高的透明度(SDD),探究该湖有色可溶性有机物(CDOM)的微生物降解特征对探究清洁水体有机物迁移转化规律具有重要意义。通过对室内微生物培养实验前后CDOM吸收和荧光光谱的对比分析,探究该湖有色可溶性有机物生物降解特征及指示意义。结果表明,经28 d微生物降解培养后CDOM吸收系数a_(254)、光谱斜率S_(275-295)平均值均减小、荧光腐殖化指数HIX增大,说明微生物降解致使CDOM浓度降低,腐殖化程度相应升高。经生物培养28 d可降解的CDOM吸收系数a 254平均降幅可达14.3%±4.8%,各点位降幅范围为4.3%~23.6%。平行因子分析获得三种荧光组分,分别为陆源类腐殖酸C1、类色氨酸C2和C3,三种荧光组分在28 d微生物降解培养过程中均主要表现为降解,极少有累积;其中类色氨酸C2和C3生物可利用性水平分别可达54.1%±18.2%和53.2%±14.3%,陆源类腐殖酸C1生物可利用性为28.2%±9.1%;培养前后CDOM荧光主要贡献组分由类色氨酸C2变为陆源类腐殖酸C1,这说明千岛湖类色氨酸生物活性高于类腐殖酸,微生物降解培养过程中亦表现为削弱类蛋白峰保留类腐殖酸峰。培养前后CDOM吸收系数差值,亦即CDOM生物可利用性Δa_(254)的高值主要集中在下游东南湖区,这与类色氨酸C2分布特征具有一定的相似性,说明千岛湖东南湖区CDOM生物可利用性最高,可能与大量类色氨酸C2赋存具有一定关系。微生物降解培养致使类色氨酸C2和C3分布特征发生改变,经培养后其高值与C1、a_(254)培养后高值分布特征相似,说明生物培养过程中可能存在类蛋白物质的产生。微生物降解培养前后C1与a_(254)均具有很好的相关性,说明微生物降解培养对陆源类腐殖酸荧光峰应用于估算有机物浓度的影响较小,培养后湖心区及东南湖区类色氨酸C2—C3高值区消失,说明在水滞留时间较长的湖区微生物活动对类色氨酸荧光峰在点源污染识别的应用存在一定的影响。
Lake Qiandao has low primary productivity and high Secchi disk depth.It is of great importance to explore the bio-availability of chromophoric dissolved organic matter(CDOM)in Lake Qiandao to unravel the carbon cycling in the lake.By comparing the changes of CDOM absorption and fluorescence pre-and post-28 days of bio-incubation,we aimed to reveal the bio-availability characteristics of CDOM in Lake Qiandao.The results showed that the mean values of a_(254) and S_(275-295) decreased,and the mean value of humification index(HIX)increased after 28 days of biodegradation.This indicated that laboratory biodegradation resulted in a decreased CDOM concentration and increased aromaticity of CDOM molecules.CDOM absorption a254 decreased by a mean of 14.3%±4.8% and with a range from 4.3% to 23.6% after 28 days of microbial degradation across the sixty sampling sites.Three fluorescent components were obtained by coupling excitation-emission matrices(EEMs)and parallel factor(PARAFAC)analysis,including a terrestrial humic-like C1,and tryptophan-like C2 and C3.Tryptophan-like C2 and C3 decreased by 54.1%±18.2%and 53.2%±14.3%,followed by C1(28.2%±9.1%),suggesting a relatively high CDOM bio-availability in Lake Qiandao.After 28 days of biodegradation,and the major fluorescence peak changed from tryptophan-like C2 to terrestrial humic-like C1,indicating that the bio-availability of the tryptophan-like component was higher than that of humic-like component,and the T peak was degraded and the A peak was retained during the 28 days of laboratory bio-incubation.High values of the difference of absorption coefficient between pre-and post-incubation,representing the bio-availability of CDOM,i.e.Δa_(254),were found in the downstream southeastern lake regions,and is similar to that of tryptophan-like C2 prior to incubation.This suggested that CDOM bio-availability was the highest in the southeastern lake areas.High values of C2 and C3 were found in the northwestern inflowing lake regions post 28 days of incubation,similar to that of C1 and a254 post 28 days of incubation,suggesting that there might be freshly production of protein-like substances during the bio-incubation.There were close correlations between C1 and a254 pre-and post-bio-incubation,indicating that terrestrial humic-like substances were bio-stable.After 28 days of bio-incubation,the high values of tryptophan-like components disappeared from the lake center and southeastern lake areas,indicating that microbial metabolism has an influence on the application of tryptophan-like fluorophores in point-source-pollution identification due to the longer water residence time of the lake area compared to the remaining lake regions.
作者
李元鹏
张柳青
江威
石玉
郭燕妮
周蕾
周永强
张运林
LI Yuan-peng;ZHANG Liu-qing;JIANG Wei;SHI Yu;GUO Yan-ni;ZHOU Lei;ZHOU Yong-qiang;ZHANG Yun-lin(State Key Laboratory of Lake Science and Environment,Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences,Nanjing 210008,China;School of Environment and Planning,University of Liaocheng,Liaocheng 252059,China;Chun’an Environmental Monitoring and Protection Station,Chun’an 311700,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《光谱学与光谱分析》
SCIE
EI
CAS
CSCD
北大核心
2021年第3期858-864,共7页
Spectroscopy and Spectral Analysis
基金
国家自然科学基金项目(41807362,41771514)
中国科学院前沿科学重点研究计划项目(QYZDB-SSW-DQC016)
江苏省自然科学基金项目(BK20181104)
中国科学院南京湖泊地理研究所启动基金项目(NIGLAS2017QD08)资助。
关键词
千岛湖
有色可溶性有机物
微生物降解
三维荧光
平行因子分析
Lake Qiandao
Chromophoric dissolved organic matter(CDOM)
Biodegradation
Excitation-emission matrices(EEMs)
Parallel factor analysis(PARAFAC)
