SGER: New Productions and Nitrogen Cycling in the Off-shoreRegions of the Black Sea

SGER：黑海近海地区的新产品和氮循环

• 批准号: 9729793
• 负责人: James McCarthy
• 金额: $ 5万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-09-15 至 1998-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9729793&HistoricalAwards=false
• 关键词: SGER; New; Productions; Nitrogen; Cycling

A. Project Summary Many scientific papers have been written that detail environmental changes in the Black Sea, and many speculate on the implications of further potential anthropogenic changes 1) in various drainage basins that provide freshwater to this sea, 2) along its coastal margins, and 3) in extraction of its resources. While the ecological effects of industrial activity and changing land and water use are most apparent in coastal regions of the Black Sea, they are also evident off-shore. For example, the observed trend of increasing nutrient concentrations and doublings of both phytoplankton biomass and primary productivity throughout the central region of the sea between the mid 1970s and early 1990s, have been attributed to anthropogenic causes. Perhaps the most dramatic basin-wide changes have been associated with the accidental introductions of carnivorous gelatinous zooplankton, most recently Mnemiopsis leydii. These species have profoundly affected Black Sea community structure. Many aspects of the Black Sea ecosystem make it an attractive system for biological oceanographers to study. Major food web perturbations allow for testing of hypotheses relating to the influence of community organization and on the flow of energy and matter. Basin scale physical processes are becoming increasingly well known, and the physical scale of this sea allows for realistic state of the art linkages among physical and biological processes in contemporary modeling efforts. The foremost of these models are nitrogen based, and they lead to conjecture regarding the sources of nitrogen that drive plankton production. However, there have been no actual studies of the dynamics of the annual nitrogen cycle and, in particular, no determinations of new production in the Black Sea. Moreover, generalizations that have been made, such as in models, are predicated upon the generalizable behavior of a Black Sea planktonic ecosystem prior to the environmental changes of the last decade. In conjunction with colleagues in Turkey, Dr. McCarthy has developed a plan to fill these gaps in knowledge of the dynamics of the nitrogen cycle in the euphoric zone of the Black Sea. Rates of N uptake, N2 fixation, and nitrogen flux among dissolved components will be measured with stable isotope techniques and interpreted within the context of plankton community and geophysical structure. This study will serve to document current conditions, provide a basis for inferring the effects of recent environmental changes, and contribute to more realistic modeling efforts of the Black Sea ecosystem. This proposed collaboration responds to an unprecedented opportunity to investigate the openwater nitrogen cycle in the Black Sea very efficiently. Turkish scientists at the METU Institute of Marine Science have just launched an intensive program to study the "Dynamics of the lower trophic levels of the Black Sea: Biogeochemical processes, and system modeling". The first field campaign in this program has begun, but a critical component, the dynamics of nitrogen fluxes among nutrient and particulate pools and trophic levels is missing. This Small Grant for Exploratory Research will provide this critical component.

A.项目摘要已经写了许多科学论文，这些论文详细介绍了黑海的环境变化，许多人推测了进一步潜在的人为变化的含义1）在各种排水盆地中，为海洋提供淡水，2）沿海边缘，以及3）在其资源中提取。尽管在黑海沿海地区，工业活动以及不断变化的土地和用水的生态影响最为明显，但它们也很明显。例如，在1970年代中期至1990年代初期，观察到的浮游植物生物量增加营养浓度和双重生产力的趋势归因于人为原因。 也许最引人注目的盆地范围的变化与肉食胶状浮游动物的意外引入有关，最近是Mnemiopsis leydii。这些物种对黑海社区结构产生了深远的影响。黑海生态系统的许多方面使其成为生物海洋学家学习的有吸引力的系统。主要食品网络扰动允许测试与社区组织以及能源和物质流动有关的假设。 盆地规模的物理过程变得越来越众所周知，并且这条海洋的物理规模允许当代建模工作中物理和生物学过程之间真正的最新状态。这些模型的最重要的是基于氮的，它们就驱动浮游生物产生的氮来源提出了猜想。 但是，没有关于年度氮循环动力学的实际研究，尤其是在黑海中没有确定新生产的决定。此外，在过去十年的环境变化之前，已经进行了概括（例如模型中）的概括性。 麦卡锡博士与土耳其的同事共同制定了一项计划，以填补这些空白，了解黑海欣快的氮循环动态。溶解成分之间的N摄取率，N2固定和氮气的速率将通过稳定的同位素技术来测量，并在浮游生物社区和地球物理结构的背景下进行解释。这项研究将记录当前状况，为推断最近的环境变化的影响提供基础，并有助于黑海生态系统的更现实的建模工作。 这项拟议的合作响应了一个前所未有的机会，可以非常有效地调查黑海的开放水氮周期。元数据海洋科学研究所的土耳其科学家刚刚启动了一个密集的计划，以研究“黑海较低的营养水平的动态：生物地球化学过程和系统建模”。该程序中的第一个现场活动已经开始，但是关键的组成部分是养分和颗粒池之间氮通量和营养水平的动力学。这项用于探索性研究的小赠款将提供这一关键组成部分。