| 典型藻型湖湾中溶解有机质及其生物可降解性的时空变化 |
| 摘要点击 882 全文点击 144 投稿时间：2024-02-01 修订日期：2024-05-10 |
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| 中文关键词 蓝藻水华 溶解性有机质（DOM） 生物可降解性 三维荧光-平行因子 偏最小二乘分析 |
| 英文关键词 cyanobacteria bloom dissolved organic matter（DOM） biodegradability three-dimensional fluorescence-parallel factor partial least squares analysis |
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| 中文摘要 |
| 溶解有机质（DOM）及其生物可降解性是评估内陆湖库有机碳收支和生态系统平衡的重要参数,与区域水文特征和生物化学过程密切相关. 选取太湖北部的藻型湖湾为研究对象,结合紫外吸收、三维荧光光谱表征和生物培养实验,分析了雨季-藻华期和旱季-藻华后期水体中DOM的浓度、结构组成和生物可降解溶解有机碳（BDOC）的时空变化. 藻华期间,藻源性有机物的释放导致梅梁湾和贡湖湾的DOM浓度显著升高,以酪氨酸和色氨酸等类蛋白组分为主（>70%）,但芳香物含量（SUVA254）、相对分子质量和腐殖化程度（HIX）较低. 相比较,竺山湾的DOM吸光度（SUVA350）、SUVA254、HIX、相对分子质量和腐殖质类组分含量较高,这与雨季地表径流输入更多的陆源性腐殖质有关,从而导致平均BDOC（31.6%）低于其他两个湖湾（38.8%）. 在旱季-藻华后期,随着蓝藻水华衰退和陆源输入减少,原位微生物降解占据主导作用,导致3个湖湾中DOM的SUVA254升高、类蛋白组分减少及类腐殖组分增加,同时平均BDOC显著下降至28.1%. 运用偏最小二乘回归分析,发现DOM光学指数可以较好地预测BDOC（R2=0.81）,其中荧光峰T/C和SR指数是最有效的正向预测因子,SUVA254为最有效的负向预测因子. 以上结果表明蓝藻水华和原位降解是影响湖泊水体中DOM生物可降解性的关键过程,并提出了一种BDOC的预测方法. |
| 英文摘要 |
| The biodegradability of dissolved organic matter （DOM） is a crucial factor in assessing the carbon balance and ecosystem equilibrium of freshwater lakes. It is closely linked to regional hydrological characteristics and biochemical processes. Taking cyanobacterial bloom-dominated bays in Lake Taihu as the research object, combined with characterization by ultraviolet absorption, three-dimensional fluorescence spectroscopy, and bioassay experiments, this study analyzed the temporal and spatial variations of DOM concentration, structural composition, and biodegradable dissolved organic carbon （BDOC） during the rainy and bloom season and the dry and post-bloom season. The results showed that during the bloom season, the release of cyanobacterial-derived organic matter led to a significant increase in DOM concentration in Meiliang Bay and Gonghu Bay, which was mainly composed of protein components, such as tyrosine and tryptophan （>70%） with a lower aromaticity （SUVA254）, molecular weight, and humification degree （HIX）. In comparison, the DOM samples in Zhushan Bay had higher absorbance （SUVA350）, SUVA254, HIX, relative molecular mass, and content of humic substances, which was associated with stronger input of terrestrial humic substances during the rainy season. As a result, the average BDOC in Zhushan Bay was lower （31.6%） compared to those in the other two bays （38.8%）. With the decline of cyanobacterial bloom and the decrease of terrestrial input in the dry and post-bloom season, in-situ degradation significantly increased SUVA254 and humic-like components while decreasing protein-like components in DOM. This resulted in a decrease in average BDOC to 28.1%. Partial least squares analysis further revealed that DOM optical indices could effectively predict BDOC （R2=0.81）, with fluorescence peaks T/C and SR indices being the most effective positive predictive factors and SUVA254 being the most effective negative predictive factor. These findings suggest that cyanobacterial blooms and in-situ degradation are crucial processes that affect the biodegradability of DOM in freshwater lakes and propose an alternative method for assessing BDOC. |
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