富营养化湖泊藻型及草型区微生物群落r对有色可溶有机物组成的影响

摘要

Chromophoric Dissolved Organic Matter (CDOM), a main component of dissolved organic carbon sources in aquatic ecosystem, plays an important role in lake ecosystem structure, primary productivity and nutrients exchange. The characteristics of algae-derived and grass-derived CDOM were investigated for algae and grass zones of Lake Taihu in autumn during cyanobacteria dying and waterweeds rotting periods, respectively. The physical and chemical properties in the two different lake zones were first analyzed; the UV visible spectrum, three-dimensional excitation-emission matrices, and parallel factor analysis were then applied to determine the differences of CDOM components; finally, bacterial communities were studied using Illuminar high-throughput sequencing. The results showed that the concentrations of NH4+-N, NO2--N, NO3--N, total N, total P and dissolved organic carbon in lake water at algae zone were higher than those at grass zone. The contents of algae-derived CDOM were significantly higher than those of grass-derived CDOM. The fluorescent components of algae-derived and grass-derived CDOM were the similar, which were humic-like, tryptophan-like, and tyrosine-like fluorescent components. However, compared to the grass-derived CDOM, the fluorescence and humification indices clearly indicated that the components of algae-derived CDOM had a higher molecular weight and were more difficult to be degraded. Further analysis suggested that the different components of CDOM could be related to the diverse bacterial communities in algae and grass zones of Lake Tailu. The algae lake zone contained abundant bacterial species, e.g., Flavobacterium, Hydrogenophaga, and Hyphomicrobium, with high capabilities of decomposing organic matter, promoting refractory organic matter accumulation in lake water and causing greater potential environmental risks.%有色可溶有机物(CDOM)是水生生态系统溶解有机碳储库的主要组成,在湖泊生态系统结构、初级生产力以及物质交换等方面发挥着重要作用.研究秋季太湖藻型区—蓝藻死亡时期及草型区—水草腐烂时期CDOM的组成差异性特征及其影响因素.首先对两类典型湖区水体的理化性质进行了分析,然后利用紫外可见光谱、三维荧光光谱结合平行因子分析的技术确定CDOM组成,最后结合Illuminar高通量测序揭示了两个区域水体中不同的微生物群落结构对CDOM组成的影响.结果表明,藻型湖水的各理化性质指标,包括NH4+-N、NO2--N、NO3--N、TN,TP,DOC的浓度都明显高于草型湖水,秋季藻源性CDOM的含量明显高于草源性CDOM的含量.虽然藻源性和草源性CDOM的荧光组分相同,即同为类腐殖、类色氨酸和类络氨酸荧光组分,然而,相比于草源性CDOM,荧光指数(FI)和腐殖化指数(HIX)均表明藻源性CDOM具有更高的分子量组成,更难被微生物利用,而造成此差异性的重要原因为两个区域微生物群落组成的差异性,藻型区水体含有更丰富的降解有机物的细菌种类,包括黄杆菌属(Flavobacterium),噬氢菌属(Hydrogenophaga)、生丝微菌属(Hyphomicrobium)等,可优先分解易于分解的有机物,残留更多难降解的有机物,具有更大的潜在的环境隐患.