Long-range atmospheric Nitrogen deposition as a driver of ecological change in Arctic lakes

远距离大气氮沉降是北极湖泊生态变化的驱动因素

• 批准号: NE/G019509/1
• 负责人: Jan Kaiser
• 金额: $ 3.48万
• 依托单位: University of East Anglia
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FG019509%2F1
• 关键词: Long; range; atmospheric; Nitrogen; deposition

The Arctic is one of the most vulnerable regions on Earth and there is clear evidence that its ecosystems are changing rapidly. These changes are generally attributed to recent global warming, the effects of which are enhanced in this region. Lakes are an important component in the Arctic landscape. However, many changes seen in the lakes could also be explained by increases in fertility caused by atmospheric deposition of nitrogen (N). We know from the records preserved in Greenland ice cores that N is deposited in the Arctic from industrial regions many thousands of miles away. Anthropogenic N fixation (conversion of inert N2 to reactive N compounds) is now greater than its natural equivalent and changes in the N cycle are arguably as important as climate change. Much of the evidence for long-term ecological change in the Arctic comes from lake sediments, which can be dated by natural radioisotopes. Studies show that the composition of algal communities has changed and algal productivity has increased over the past 100 years. Although many researchers think these changes are due to global warming, increased temperature is only one aspect of global environmental change caused by human activity. There are a number of other factors, some indirectly related to climate that could alter community structure in lakes, for example increased rates of weathering or acidification. However, as most arctic lakes are very nutrient poor, any increase in productivity needs an increase in nutrient availability. One important source of nutrients to remote lakes is atmospheric deposition of N. There is evidence from both alpine and arctic lakes that long-term, low level deposition of N may be affecting lake productivity and lake biology. We propose to test the hypothesis that N deposition is driving ecological change in the Arctic by studying lakes in SW Greenland. We have chosen this area because records show that temperature has not increased during the 20th century; unlike large parts of the Arctic. Our preliminary results, indicate that N deposition has increased in this area since the mid-19th century. Our study incorporates contemporary ecology, N deposition monitoring and the study of lake sediments. By examining ten areas along a marked precipitation and N deposition gradient we will be able to assess the influence of N inputs to lakes through seasonal monitoring and experimental work. We will use contemporary ecological experiments to determine if phytoplankton are nutrient limited, and whether this is through nitrogen, phosphorus, or co-limitation. We will measure the N content and isotopic fingerprint of rain and snow (wet deposition) and aerosol particles (dry deposition). Remarkably few measurements of N deposition exist in the Arctic. Our measurements will contribute to an international focus on long-range atmospheric pollution transport. Finally, these modern studies will be coupled with analyses of lake sediments to establish longer-term trends in SW Greenland. The project will help us understand the causes of ecological change throughout the Arctic. SW Greenland is typical of much of the Arctic in terms of lake density, precipitation patterns and vegetation. If we establish that lakes in this region have become more productive recently, there are clear implications for large areas of the Arctic which have experienced recent warming since long-range N transport is a global phenomenon. It is likely that warming and N enrichment act in a similar and synergistic way, resulting in lakes showing a sensitive and enhanced response to even small increases in temperature. Possible interactions between nutrient deposition and carbon cycling are also important for understanding biogeochemical cycling. For example, enhanced N deposition may release bacteria from nutrient limitation, increasing rates of respiration in lakes, increasing CO2 efflux to the atmosphere, and hence providing a feedback into the climate system.

北极是地球上最脆弱的地区之一，有明确的证据表明其生态系统正在迅速变化。这些变化通常归因于最近的全球变暖，该变暖的影响在该地区的影响得到了增强。湖泊是北极景观中的重要组成部分。然而，湖泊中看到的许多变化也可以通过氮气沉积引起的生育能力的增加来解释。我们从保存在格陵兰冰核心的记录中知道，N被存放在数千英里外的工业区域中。现在，人为N固定（将惰性N2转化为反应性N化合物）大于其自然等效物，并且N周期的变化可以说与气候变化一样重要。北极长期生态变化的大部分证据来自湖泊沉积物，可以通过自然放射性病来定位。研究表明，藻类群落的组成发生了变化，并且在过去100年中，藻类的生产率也有所提高。尽管许多研究人员认为这些变化是由于全球变暖，但温度升高只是人类活动引起的全球环境变化的一个方面。还有许多其他因素，有些与气候间接相关，这些因素可能会改变湖泊中的社区结构，例如风化率提高或酸化率。但是，由于大多数北极湖泊的营养很差，因此生产力的任何提高都需要增加养分的可用性。偏远湖泊的养分的一种重要来源是N的大气沉积。有来自高山和北极湖泊的证据表明，长期，低水平的n可能会影响湖泊生产力和湖泊生物学。我们建议检验以下假设：N沉积通过研究SW Greenland的湖泊来推动北极的生态变化。我们之所以选择该区域，是因为记录显示20世纪温度没有升高。与北极的大部分不同。我们的初步结果表明，自19世纪中叶以来，该领域的N沉积已有增加。我们的研究结合了当代的生态学，N沉积监测和对湖泊沉积物的研究。通过检查沿明显的降水和N沉积梯度的十个区域，我们将能够通过季节性监测和实验工作评估N投入对湖泊的影响。我们将使用当代生态实验来确定浮游植物是否受到养分有限，以及这是通过氮，磷还是共限量。我们将测量雨水（湿沉积）和气溶胶颗粒（干沉积）的N含量和同位素指纹。北极中很少有N沉积的测量值。我们的测量将有助于国际关注远程大气污染运输。最后，这些现代研究将与对湖泊沉积物的分析相结合，以在SW格陵兰建立长期趋势。该项目将帮助我们了解整个北极地区生态变化的原因。 SW Greenland在湖泊密度，降水模式和植被方面是大部分北极的典型代表。如果我们确定该地区的湖泊最近变得更加生产力，那么对于北极地区的大片地区有明显的影响，这些地区最近经历了近期变暖，因为远程N运输是一种全球现象。变暖和n富集可能以类似且协同的方式，导致湖泊表现出对温度升高的敏感且增强的反应。营养沉积与碳循环之间的可能相互作用对于理解生物地球化学循环也很重要。例如，增强的N沉积可能会从营养限制，湖泊中呼吸速度增加，增加对大气的二氧化碳外排，从而向气候系统提供反馈。

项目成果

Nitrate postdeposition processes in Svalbard surface snow

• DOI: 10.1002/2013jd021234
• 发表时间: 2014-11
• 期刊: Journal of Geophysical Research: Atmospheres
• 作者: M. Björkman;C. Vega;R. Kühnel;F. Spataro;A. Ianniello;G. Esposito;J. Kaiser;A. Marca;A. Hodson;E. Isaksson;T. Roberts

Spatial variations in snowpack chemistry and isotopic composition of NO<sub>3</sub><sup>-</sup> along a nitrogen deposition gradient in West Greenland

积雪化学和 NO 同位素组成的空间变化

• DOI: 10.5194/bg-2017-140
• 发表时间: 2017
• 作者: Curtis C

Stable isotopes reveal independent carbon pools across an Arctic hydro-climatic gradient: Implications for the fate of carbon in warmer and drier conditions

稳定同位素揭示了北极水文气候梯度上的独立碳库：对温暖和干燥条件下碳命运的影响

• DOI: 10.1002/lol2.10119
• 发表时间: 2019
• 期刊: Limnology and Oceanography Letters
• 影响因子: 7.8
• 作者: Osburn C

A 60 yr record of atmospheric carbon monoxide reconstructed from Greenland firn air

• DOI: 10.5194/acp-13-7567-2013
• 发表时间: 2013-01-01
• 期刊: ATMOSPHERIC CHEMISTRY AND PHYSICS
• 影响因子: 6.3
• 作者: Petrenko, V. V.;Martinerie, P.;White, J. W. C.
• 通讯作者: White, J. W. C.

Nitrate stable isotopes and major ions in snow and ice samples from four Svalbard sites

斯瓦尔巴特群岛四个地点的雪和冰样本中的硝酸盐稳定同位素和主要离子

• DOI: 10.3402/polar.v34.23246
• 发表时间: 2015
• 期刊: Polar Research
• 影响因子: 1.9
• 作者: Vega C