Biocomplexity in the Environment (BE), Coupled Biogeochemical Cycles (CBC): Complex Molecular to Global Interactions and Feedbacks in the Marine Dimethylsulfide (DMS) Cycle

海洋生态系统是一个复杂的地球物理-生物地球化学网络的一部分，它转化物质和能量，并为生命创造条件。这个网络的不同部分之间的反馈在很大程度上是通过交换具有重要辐射意义的生物微量气体来调节的。其中一个反馈涉及海洋浮游生物、挥发性硫化合物二甲基硫化物（DMS）和全球气候。在这种反馈中，海洋浮游植物和食物网产生的DMS进入对流层，在那里被氧化成硫酸盐颗粒，从而影响云的反照率，从而影响气候。大规模的气候变化反过来又影响海洋中浮游植物的丰度和食物网过程，从而关闭了反馈循环。这种反馈回路的强度——甚至是信号——仍未得到解决，主要是因为影响DMS浓度的生物地球化学和生态过程的极其复杂的网络。在这个循环中，迷人的新相互作用仍在以某种规律被发现，但这个系统的机械和预测数学模型尚未纳入许多这些发展。此外，还没有同时测量海洋DMS循环中所有相关速率和浓度的实地研究，也没有包括重要的地球物理或化学参数的复杂相互作用或测量，从而妨碍了模式准确绘制地表DMS浓度时空变化的能力。这项工作将：1)在两个海洋生物群系（副热带环流和南大洋）进行密集实地研究期间，测量和模拟所有已知的DMS和相关物种浓度的相关通量；2)在建议的野外测量和其他现有测量和模型的基础上建立全球海洋DMS模型；3)利用该模型评估气候与海洋DMS循环之间反馈的可能性。DMS生物地球化学系统代表了一个易于处理的研究课题，可以帮助理解区域和全球尺度上生物圈-地圈调节的复杂性。DMS系统也为食物网依赖的生物地球化学过程提供了一个优秀的、可研究的模型。通过对DMS循环复杂控制因素的研究，有助于揭示影响海洋生物生态分布的关键因素和主要营养元素的生物地球化学循环。推进DMS生物地球化学知识将有助于更好地预测局部、区域和全球尺度对预期气候变化的反应，并为维持地球生命的生物地球化学-地球物理网络内部的联系提供有价值的见解。

Matrai0221748Ocean ecosystems are part of a complex geophysical-biogeochemical web that transforms matter and energy and sets the conditions for life. Feedback between different parts of this web is mediated to a significant degree by the exchange of radiatively important, biogenic trace gases. One such feedback involves marine plankton, the volatile sulfur compound dimethylsulfide (DMS), and global climate. In this feedback, DMS produced by marine phytoplankton and the food web enters the troposphere and is oxidized there to sulfate particles, which influence cloud albedo and, consequently, climate. Large-scale climate change, in turn, affects phytoplankton abundance and food web processes in the oceans and thereby closes the feedback loop. The strength-and even the sign-of this feedback loop is still unresolved, largely because of the exceedingly complex network of biogeochemical and ecological processes that affect the concentration of DMS. Fascinating new interactions in this cycle are still being discovered with some regularity, but mechanistic and prognostic mathematical models of this system have yet to incorporate many of these developments. Furthermore, there have been no field studies in which all of the relevant rates and concentrations in the marine DMS cycle have simultaneously been measured, nor have complex interactions or measurements been included for important geophysical or chemical parameters, hampering the ability of models to accurately map spatial and temporal variations in surface DMS concentrations. This effort will: 1) Measure and model all known relevant fluxes of concentrations of DMS and related species during intensive field studies in two ocean biomes: a subtropical gyre and the Southern Ocean; 2) Develop a global marine DMS model built upon the proposed field measurements and other existing measurements and models; and 3) Use such a model to evaluate the potential for feedbacks between climate and the marine DMS cycle. The DMS biogeochemical system represents a tractable research subject that can aid in understanding the complexities involved in biosphere-geosphere regulation at the regional and global scales. The DMS system also serves as an excellent, research- accessible model for food-web dependent biogeochemical processes. This investigation of the complex controls on the DMS cycle should shed light on the critical factors influencing the ecological distributions of organisms in the sea and the biogeochemical cycles of major nutrient elements. Advancing the knowledge of DMS biogeochemistry will allow better predictions of the local, regional and global scale responses to anticipated shifts of climate, and provide valuable insights into the connections within the biogeochemical-geophysical web that sustains life on Earth.