人类活动增加了氮磷大气传输通量，改变了全球氮磷循环。与氮完全不同，大气中磷几乎全部存在于大气颗粒物。因此，与氮相比，生态系统大气磷沉降传统上被忽略了，并被排出在磷循环之外。然而，最近研究发现生物质燃烧产生的气溶胶极大地提高了大气磷含量，使之成为磷循环的重要部分。大气磷排放的增加可能强烈地影响磷短缺的陆地和海洋生态系统生物地球化学。因此，近些年来大气磷沉降受到国外学者广泛关注，尤其是高原贫营养湖泊的大气磷沉降。虽然我国分布有众多高原湖泊，但是关于高原湖泊大气磷沉降的研究十分有限。本项目以青海湖为研究对象，采用观测与室内外模拟等手段，研究青海湖大气磷沉降及其生态效应。内容包括：大气P沉降通量、N/P沉降比例及其季节变化，大气N/P沉降对青海湖营养水平的影响，大气沉降颗粒物中P的形态及植物有效性。本研究可丰富高原咸水湖泊磷生物地球化学过程与循环理论，助于理解大气沉降对青海湖营养水平与演化的影响。

Over the last century, human activities have led to an increased flux of nitrogen and phosphorus through the atmosphere and thus have altered the global cycles of these elements. Unlike nitrogen, phosphorus has no significant gaseous phase under environmental temperature and pressure and is therefore almost entirely particle-associated in the atmosphere. Therefore, atmospheric deposition of P to ecosystems has traditionally been thought to be negligible in comparison with nitrogen and not typically been included in P cycling studies. However, recent studies have highlighted the role of combustion, primary biogenic and biomass burning aerosols as significant sources of P. These increases may thus strongly impact the terrestrial and oceanic biogeochemistry where sources of P are otherwise low (e.g. alpine oligotrophic lakes). Therefore, recently, atmospheric P deposition has received attention, particularly in alpine oligotrophic lakes where P generally limits phytoplankton growth. Although there are many alpine lakes in China, the study on atmospheric P deposition to them is extremely limited. The objectives of this project are to measure the flux of atmospheric P deposition to Qinghai lake and understand its ecological importance, using field monitoring, lab experiments, field experiments, and model simulation. The major contents of this study are: (1) Flux of atmospheric P deposition to Qinghai lake and its seasonal change; (2) Stoichiometric N/P ratio of atmospheric fallout to Qinghai lake and its seasonal change; (3) Effect of atmospheric P and N deposition to the trophic of Qinghai lake; and (4) P dissolution and phytoavailability of atmospheric fallout in Qinghai lake.