太湖藻型湖区沉积物中生物易降解物质组成及分布规律

Composition and distribution of biodegradable compounds in phytoplankton-dominated zone of Lake Taihu

为研究富营养化湖泊藻型湖区沉积物中生物易降解有机质的组成及其垂向分布特征,选取太湖竺山湾湖滨带和开敞湖区采集沉积物柱状样,利用微电极技术测定沉积物水界面理化指标的剖面特征,并对沉积物中含水率、烧失量、色素含量、总有机碳、总氮以及生物易降解物质(总蛋白、总糖和总脂)进行测定.结果表明:藻型湖区沉积物水界面处溶解氧、pH和氧化还原电位在垂向剖面上呈现出随深度增加而下降的趋势,空间上存在明显的异质性,湖滨带沉积物水界面溶解氧、pH和氧化还原电位显著低于开敞湖区,而沉积物水界面H2S浓度在垂向上则表现为随深度先降低而后升高的趋势.此外,藻型湖区沉积物中生物易降解有机质的组成和分布同样存在明显的空间异质性.组成上以脂类(7.7 mg/g)为主,其次是糖类(4.5 mg/g),蛋白质(0.8 mg/g)含量最低;空间上,湖滨带沉积物中生物易降解有机质含量显著高于开敞湖区,表层15 cm以上沉积物含水率和烧失量较高,有机质含量丰富.

To better understand the distribution and composition of sedimentary bioclastic material in phytoplankton-dominated eutrophic lakes,we combined a spatial survey of surface sediments with sediment core analyses to quantify moisture content,ignition loss,pigments,total organic nitrogen,total nitrogen and biodegradable compounds changes in the littoral zones and off-shore areas.Results show that dissolved oxygen,pH and oxidation-reduction potential presented a clear downward trend with increasing depth,while the H2S concentrations gradually decreased with increasing depth and then increased in deeper layers until they reached a maximum and remained stable.In the littoral zones,the physicochemical parameters were mostly higher than that in the offshore areas.In addition,the biodegradable compounds showed significant spatial variability.Results show that lipids (7.7 mg/g),followed by carbohydrates (4.5 mg/g),was the dominant component of sedimentary bioclastic material.Data shows that the distribution of high moisture content,ignition loss and biodegradable compounds were mainly localization in the surface 15 cm of sediments.