不同水文情景下洪泽湖、骆马湖有色可溶性有机物生物可利用性特征

运用三维荧光-平行因子分析(EEMs-PARAFAC)和室内生物培养实验,分析了洪泽湖和骆马湖有色可溶性有机物(CDOM)生物降解特征对不同水文情景的响应。结果表明,(1)平行因子分析得到3类荧光组分,类腐殖质C1、类色氨酸C2和类酪氨酸C3。(2)经28天生物培养后,枯水期洪泽湖、骆马湖溶解性有机碳DOC生物可利用性(BDOC,分别为17%±4%, 15%±4%)高于丰水期(分别为5%±5%, 10%±7%),且枯水期%BDOC高值主要分布于入湖口区域。(3)枯水期两湖泊比紫外吸收系数SUVA254和类腐殖质C1荧光强度显著高于培养前,即ΔSUVA254和ΔC1为负值,而类酪氨酸荧光强度显著低于培养前,即ΔC3为正值,表明了枯水期类酪氨酸生物可利用性较高,产生了较为稳定的类腐殖质,增加了样品的腐殖化程度。(4)BDOC和%BDOC分别与ΔSUVA254有较好的负相关性, BDOC及%BDOC与ΔC3,%ΔC3均有较好的正相关性。这意味着两个湖泊CDOM组成直接影响其生物可利用性。

The Bioavailability Characteristics of CDOM in Lake Hongze and Lake Luoma under Different Hydrological Scenarios

We investigated the bioavailability characteristics of chromophoric dissolved organic matter(CDOM) in different hydrological scenarios of Lake Hongze and Lake Luoma using bio-incubation experiments coupled with excitation-emission matrices and parallel factor analysis(EEMs-PARAFAC). The results showed that(1) Three fluorescent components were obtained using PARAFAC, including a humic-like C1, a tryptophan-like C2 and a tyrosine-like C3.(2) After 28 days of bio-incubation, the bioavailability of dissolved organic carbon(BDOC) in Lake Hongze and Lake Luoma in dry season(17%±4% and 15%±4%) was higher than that in flood season(5%±5% and 10%±7%), and the high %BDOC values of the two lakes were mainly distributed in the inflowing river mouths.(3) The specific absorbance at 254 nm SUVA254 and humic-like components in the two lakes during dry season was significantly higher than that pre-bio-incubation, and ΔSUVA254 and ΔC1 were negative. The tyrosine-like component was significantly lower than that pre-bio-incubation and ΔC3 was positive, indicating that the microorganisms preferentially utilized the less stable tyrosine-like component in the dry season, and produced more stable humic-like C1 and also increased the humification of the samples collected from the two lakes.(4) There were significant negative correlations between BDOC, %BDOC and ΔSUVA254, ΔC3, %ΔC3, respectively. These results indicated that CDOM optical composition directly affects its bioavailability in the two lakes.