State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, PR China.
State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, PR China.
Sci Total Environ. 2018 Jun 1;625:27-38. doi: 10.1016/j.scitotenv.2017.12.275. Epub 2017 Dec 27.
The concentrations and isotopic compositions of dissolved inorganic carbon (DIC) and particulate organic carbon (POC) were measured in order to better constrain the sources and cycling of POC in Lake Fuxian, the largest deep freshwater lake in China. Model results based on the combined δC and ΔC, showed that the average lake-wide contributions of autochthonous POC, terrestrial POC, and resuspended sediment POC to the bulk POC in Lake Fuxian were 61%, 22%, and 17%, respectively. This indicated autochthonous POC might play a dominant role in sustaining large oligotrophic lake ecosystem. A mean 17% contribution of resuspended sediment POC to the bulk POC implied that sediment might have more significant influence on aquatic environment and ecosystem than previously recognized in large deep lakes. The contributions of different sources POC to the water-column POC were a function of the initial composition of the source materials, photosynthesis, physical regime of the lake, sediment resuspension, respiration and degradation of organic matter, and were affected indirectly by environmental factors such as light, temperature, DO, wind speed, turbidity, and nutrient concentration. This study is not only the first systematic investigation on the radiocarbon and stable isotope compositions of POC in large deep freshwater lake in China, but also one of the most extensive radiocarbon studies on the ecosystem of any great lakes in the world. The unique data constrain relative influences of autochthonous POC, terrestrial POC, and resuspended sediment POC, and deepen the understanding of the POC cycling in large freshwater lakes. This study is far from comprehensive, but it serves to highlight the potential of combined radiocarbon and stable carbon isotope for constraining the sources and cycling of POC in large lake system. More radiocarbon investigations on the water-column POC and the aquatic food webs are necessary to illuminate further the fate of autochthonous POC, terrestrial POC, and resuspended sediment POC, and their eco-environmental effects.
为了更好地约束中国最大的深水淡水湖中抚仙湖的颗粒有机碳（POC）的来源和循环，我们测量了溶解无机碳（DIC）和颗粒有机碳（POC）的浓度和同位素组成。基于δC 和 ΔC 的综合模型结果表明，自生源 POC、陆源 POC 和再悬浮沉积物 POC 对抚仙湖整体 POC 的平均湖泊贡献分别为 61%、22%和 17%。这表明自生源 POC 可能在维持大型贫营养湖泊生态系统中发挥主导作用。再悬浮沉积物 POC 对整体 POC 的平均 17%的贡献意味着沉积物对大型深水湖泊的水生环境和生态系统可能比以前认为的更为重要。不同来源 POC 对水柱 POC 的贡献是源材料初始组成、光合作用、湖泊物理状态、沉积物再悬浮、有机物呼吸和降解以及光照、温度、DO、风速、浊度和营养浓度等环境因素间接影响的函数。本研究不仅是中国大型深水淡水湖中 POC 的放射性碳和稳定同位素组成的首次系统调查，也是世界上任何大湖生态系统中最广泛的放射性碳研究之一。独特的数据约束了自生源 POC、陆源 POC 和再悬浮沉积物 POC 的相对影响，加深了对大型淡水湖中 POC 循环的理解。本研究远非全面，但它突出了放射性碳和稳定碳同位素结合用于约束大型湖泊系统中 POC 来源和循环的潜力。需要对水柱 POC 和水生食物网进行更多的放射性碳调查，以进一步阐明自生源 POC、陆源 POC 和再悬浮沉积物 POC 的命运及其生态环境效应。
