Abstract：
Phosphorus (P) chemistry and its dynamic cycling are essential for understanding aquatic primary productivity and ecosystem structure. However, there is a lack of knowledge on P chemistry in pristine aquatic ecosystems, such as in Antarctica. Here, we applied the Standards, Measurements and Testing Program (SMT) procedure and nuclear magnetic resonance spectroscopy (NMR) to reveal P speciation in two types of lacustrine sediment cores collected from Inexpressible Island, Ross Sea, East Antarctica. The Positive Matrix Factorization Model and Generalized Additive Models were applied to quantitatively identify the P sources and estimate relative effects of various environmental factors on the speciation. Our results demonstrate that orthophosphate, mainly as Ca-P, is the major component and the ortho-monoesters are the predominant organic phosphorus (OP) form in lacustrine sediments. Ornithogenic lacustrine sediments have a higher content of P as Ca-P than sediments with little or no penguin influence. Our model further suggests that penguin guano is the most important source for Ca-P, accounting for 80%, while detrital input is the predominant source for Fe/Al-P (up to 90%). The content of ortho-monoesters, as revealed by NMR, declines with depth, reflecting mineralization process of OP in the sediments. Moreover, we observed higher relative proportions of organic P in the sediments with little guano influence and the deposition of organic P are likely facilitated by microbial mats. Overall, our data suggest that burial of P in Antarctic lakes is sensitive to different P sources and sedimentary environments. The relatively higher bioavailable phosphorus in lacustrine sediments largely controls growth of aquatic microbial mats in oligotrophic lakes and ponds in Antarctica. The sediment profile data also indicate that P burial increased during the Medieval Climate Anomaly period, and climate warming is more conducive to P burial through the expansion of penguin populations and productivity of microbial mats. Our findings represent the first systematic understanding of natural P cycling dynamics and its main controlling factors in pristine ponds with different organic sources in Antarctica.
摘要：
磷（P）化学及其动态循环对于理解水生初级生产力和生态系统结构至关重要。然而,对原始水生生态系统中的磷化学缺乏了解，比如在南极洲。这里,我们应用了标准，测量和测试程序（SMT）程序和核磁共振波谱（NMR）揭示了从不可表达岛收集的两种类型的湖相沉积物岩心中的磷形态，罗斯海,东南极洲。应用正矩阵分解模型和广义加性模型来定量识别P源，并估计各种环境因素对形态的相对影响。我们的结果表明正磷酸盐，主要为Ca-P，是湖相沉积物中的主要成分，而原单酯是主要的有机磷（OP）形式。鸟源性湖相沉积物的Ca-P含量高于企鹅影响很小或没有企鹅影响的沉积物。我们的模型进一步表明，企鹅鸟粪是钙磷的最重要来源，占80%,而碎屑输入是Fe/Al-P的主要来源(高达90%)。原单酯的含量，核磁共振显示，随着深度的下降，反映了沉积物中OP的矿化过程。此外，我们观察到沉积物中有机磷的相对比例较高，而鸟粪的影响很小，有机磷的沉积可能是由微生物垫促进的。总的来说,我们的数据表明，南极湖泊中磷的埋藏对不同的磷来源和沉积环境敏感。湖相沉积物中相对较高的生物可利用磷在很大程度上控制了南极贫营养湖泊和池塘中水生微生物垫的生长。沉积物剖面数据还表明，在中世纪气候异常时期，磷埋藏增加，而气候变暖通过企鹅种群的扩大和微生物垫的生产力更有利于磷埋藏。我们的发现代表了对南极洲不同有机来源的原始池塘中自然磷循环动力学及其主要控制因素的首次系统理解。
