Ocean Chemistry

氮以硝酸盐、亚硝酸盐和铵的形式存在，是所有生命的重要营养物。在开阔的海洋中，固定氮的数量控制着初级生产和随后从大气中去除碳的数量。因此氮也有调节气候的作用。虽然固定氮在开阔的海洋中可能是有限的，但在沿海地区，由于人类活动，它往往是过量的。人类继续通过肥料使用、废水排放和水产养殖饲料向沿海海洋添加固定氮。过量的氮引起环境问题，使环境退化，使其不适合作为动物栖息地或人类用于旅游和商业目的。这些问题包括藻类过度生长、水中氧气耗尽和鱼类死亡。布赫瓦尔德博士的研究项目涉及全球氮循环的两个方面。她在西北大西洋的苏格兰大陆架和拉布拉多海进行研究，旨在预测这个气候重要地区固定氮的变化。它将有助于模拟和预测未来的气候变化。目前有迹象表明，该地区的氮含量正在减少。她的工作将促进对这种减少将如何影响未来碳吸收变化的理解。她的研究项目的其他主要目标集中在新斯科舍省沿海水域氮的释放上。在第一个项目中，她将确定当地污水处理厂氮的同位素特征。这将提高追踪人类排泄物中氮进入环境的能力。她的最后一个主要目标是帮助促进新斯科舍省海藻养殖业的发展。氮是限制海藻生长的主要营养物质之一。在选择合适的养殖地点时，了解未来水产养殖地点的氮利用率将是必不可少的。通过所有这些项目，布赫瓦尔德博士将使用天然丰度稳定的同位素来追踪氮。她的实验室还将继续专注于开展实验工作，确定新型氮循环过程的同位素系统。这些实验中确定的同位素参数可用于分析西北大西洋、废水处理厂和海藻养殖场的天然丰度同位素。

Nitrogen, in the forms of nitrate, nitrite and ammonium, is an important nutrient for all life. In the open ocean the amount of fixed nitrogen controls the amount of primary production and subsequent carbon removal from the atmosphere. Therefore nitrogen also has a role in regulating climate. While fixed nitrogen can be limiting in the open ocean, in coastal areas it is often in excess due to human activities. Humans continue to add fixed nitrogen to the coastal ocean through fertilizer use, wastewater run off and aquaculture feeds. Excess nitrogen causes environmental problems that degrade the environment, making it unsuitable as animal habitat or for human use for tourism and commercial purposes. These issues include overgrowth of algae, oxygen depletion in the water and fish kills. Dr. Buchwald's research program tackles both sides of the global nitrogen cycle. Her research in the Northwest Atlantic on the Scotian Shelf and Labrador Sea aims to predict changes in fixed nitrogen in this climatically important region. It will help model and predict future changes in climate. Currently there is indication that the amount of nitrogen is decreasing in this region. Her work will advance understanding of how this decrease will affect future changes in carbon uptake. The other main objectives in her research program focus on the release of nitrogen in the coastal waters of Nova Scotia. In the first project she will determine the isotopic signature of nitrogen in local wastewater treatment plants. This will improve the ability to track nitrogen from human waste into the environment. Her last main objective is to help facilitate the growth of seaweed aquaculture in Nova Scotia. Nitrogen is one of the major nutrients that limits the growth of seaweed. Understanding nitrogen availability in prospective aquaculture sites will be imperative when choosing suitable locations to farm. Through all these projects Dr. Buchwald will use natural abundance stable isotopes to track the nitrogen. Her laboratory will also continue to specialize in conducting experimental work determining isotope systematics of novel nitrogen cycling processes. The isotope parameters defined in these experiments can be used in the analysis of natural abundance isotopes in the Northwest Atlantic, wastewater treatment plants and on seaweed farms.