Particulate organic carbon formation and phosphorus/iron supply ratios along pH and trophic gradients in lakes

在全球范围内，湖泊沉积物储存了非常大量的碳。沉积物中藻类残留物的存在，如色素、细胞壁等，表明沉积物中的碳部分来自藻类。然而，有证据表明，藻类碳很容易被微生物群落矿化，因此似乎一定有一个主要的非生物来源的沉积物碳。在上一个赠款周期中，我的实验室的工作表明，人工太阳光照射酸性溪流水会导致溶解有机碳(DOC)形成颗粒有机碳(POC)，颗粒铁的形成起主要作用，可能是因为DOC附着在新形成的颗粒铁的表面。我们推测，这一机制在将DOC转移到沉积物中起着主要作用。这项建议的第一部分试图通过研究在没有紫外线的情况下酸性和非酸性水域中POC的形成程度来扩展这项工作。

Globally, lake sediments store a very large amount of carbon. The presence of algal remains in sediments such as pigments, cell walls, etc indicates that sediment carbon is partially derived from algae. However, evidence shows that algal carbon is readily mineralized by the microbial community so it appears that there must be a major non-biological source of sediment carbon. During the last grant cycle, work in my laboratory demonstrated that irradiation of acidic stream waters with artificial sunlight resulted in formation of particulate organic carbon (POC) from dissolved organic carbon (DOC) and that formation of particulate iron played a major role, probably because DOC adheres to the surface of newly formed particulate iron. We hypothesize that this mechanism plays a major role in transferring DOC to sediments. The first part of this proposal seeks to extend this work by examining the extent of POC formation in acidic and non-acidic waters in the absence of UVB.