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/G019193/1
• 负责人: Suzanne McGowan
• 金额: $ 3.35万
• 依托单位: University of Nottingham
• 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%2FG019193%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，其影响在该区域得到加强。湖泊是北极景观的重要组成部分。然而，在湖泊中看到的许多变化也可以用氮（N）的大气沉积引起的肥力增加来解释。我们从格陵兰冰芯中保存的记录中得知，氮是从数千英里外的工业区沉积在北极的。人为固氮（惰性N2转化为活性氮化合物）现在大于其自然等效物，氮循环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，可以通过天然放射性同位素确定年代。研究表明，在过去100年里，藻类群落的组成发生了变化，藻类生产力有所提高。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。还有一些其他因素，其中一些与气候间接相关，可能会改变湖泊的群落结构，例如风化或酸化速度加快。然而，由于大多数北极湖泊的营养非常贫乏，任何生产力的提高都需要增加营养的可用性。偏远湖泊营养物质的一个重要来源是大气沉积的N。有证据表明，从高山和北极湖泊，长期，低水平沉积的N可能会影响湖泊生产力和湖泊生物。我们建议通过研究格陵兰岛西南部的湖泊来检验氮沉降正在推动北极生态变化的假设。我们之所以选择这个地区，是因为记录显示，与北极大部分地区不同，世纪的气温并没有上升。我们的初步结果表明，自世纪中期以来，该地区的氮沉降有所增加。我们的研究结合了当代生态学，氮沉积监测和湖泊沉积物的研究。通过检查10个地区沿着一个显着的降水和N沉积梯度，我们将能够评估的影响，N输入湖泊通过季节性监测和实验工作。我们将使用当代生态实验来确定浮游植物是否受到营养限制，以及这是否是通过氮，磷或共同限制。我们将测量雨雪（湿沉降）和气溶胶粒子（干沉降）的氮含量和同位素指纹。在北极，对氮沉降的测量非常少。我们的测量结果将有助于国际社会关注大气污染物的远距离传输。最后，这些现代研究将与湖泊沉积物分析相结合，以确定格陵兰岛西南部的长期趋势。该项目将帮助我们了解整个北极生态变化的原因。格陵兰西南部在湖泊密度、降水模式和植被方面是北极大部分地区的典型。如果我们确定该地区的湖泊最近变得更加富有成效，那么对于经历了最近变暖的北极大面积地区来说，有明显的影响，因为长距离N传输是一种全球现象。很可能变暖和氮富集以类似的协同方式起作用，导致湖泊对温度的微小上升表现出敏感和增强的反应。养分沉积和碳循环之间可能的相互作用对于理解地球化学循环也很重要。例如，增加氮沉降可以将细菌从营养限制中释放出来，增加湖泊中的呼吸速率，增加二氧化碳向大气的排放，从而为气候系统提供反馈。

项目成果

Impact of the Little Ice Age on the biological structure of lakes in South West Greenland.

小冰期对格陵兰西南部湖泊生物结构的影响。

• 发表时间: 2013
• 作者: Whiteford, E.

(2018) Regional variability in the atmospheric nitrogen deposition signal and its transfer to the sediment record in Greenland lakes. 10.1002/lno.10936

(2018)大气氮沉降信号的区域变化及其向格陵兰湖泊沉积物记录的转移。

• 发表时间: 2018
• 期刊: Limnology and Oceanography
• 影响因子: 4.5
• 作者: Anderson NJ

Nutrient limitation of periphyton growth in arctic lakes in south-west Greenland

• DOI: 10.1007/s00300-014-1524-8
• 发表时间: 2014-09-01
• 期刊: POLAR BIOLOGY
• 影响因子: 1.7
• 作者: Hogan, E. J.;McGowan, S.;Anderson, N. J.
• 通讯作者: Anderson, N. J.

The Arctic in the Twenty-First Century: Changing Biogeochemical Linkages across a Paraglacial Landscape of Greenland.

• DOI: 10.1093/biosci/biw158
• 发表时间: 2017-02-01
• 期刊: Bioscience
• 影响因子: 10.1
• 作者: Anderson NJ;Saros JE;Bullard JE;Cahoon SMP;McGowan S;Bagshaw EA;Barry CD;Bindler R;Burpee BT;Carrivick JL;Fowler RA;Fox AD;Fritz SC;Giles ME;Hamerlik L;Ingeman-Nielsen T;Law AC;Mernild SH;Northington RM;Osburn CL;Pla-Rabès S;Post E;Telling J;Stroud DA;Whiteford EJ;Yallop ML;Yde JC
• 通讯作者: Yde JC

Regional and seasonal limnology of lakes across South West Greenland under ice cover and ice-free conditions.

冰盖和无冰条件下格陵兰岛西南部湖泊的区域和季节性湖泊学。

• 期刊: Arctic, Antarctic and Alpine Research.
• 作者: Whiteford, E.J.