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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

基本信息

批准号：
NE/G020027/1
负责人：
Vivienne Jones
金额：
$ 21.27万
依托单位：
University College London
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%2FG020027%2F1
关键词：
Long range atmospheric Nitrogen deposition

项目摘要

There is now unambiguous evidence that ecosystems in the Arctic are changing. This is generally attributed to global warming, effects of which are particularly enhanced in this region. In this project we will test the hypothesis that long-range atmospheric deposition of nitrogen (N) is also an important driver of ecological change in sensitive arctic ecosystems. Lakes are an important component of these landscapes and are vital for regional biogeochemical fluxes, especially those of carbon (C). Much of the evidence for long-term ecological change in the Arctic is derived from lake sediments. The composition of algal communities has changed and algal productivity has increased. Although many researchers attribute these changes to global warming, increased temperature is only one aspect of global environmental change caused by anthropogenic disruption of biogeochemical cycles. There are a number of other factors, some indirectly related to climate, that could alter community structure in lakes; increased rates of weathering, alkalinity export and changing surface water pH. However, as most arctic lakes are nutrient limited, any increase in productivity requires an increase in nutrient availability. One important source of nutrients to remote lakes is atmospheric deposition of N. Anthropogenic fixation of N is greater than natural rates of fixation and disruption of the N cycle arguably represents a comparable threat to remote ecosystems as climate change. There is evidence from both alpine lakes and preliminary work elsewhere in the Arctic that long-term, low level deposition of N may be affecting lake productivity and biological structure. We propose to test the hypothesis that N deposition is driving ecological change in the Arctic by studying lakes in SW Greenland where air temperature has not increased during the 20th century; unlike large parts of the Arctic. Our preliminary results, together with ice core data, indicate that N deposition has increased in this area since the mid-19th century. Our study incorporates contemporary ecology, precipitation monitoring and palaeolimnology. By careful site selection of three areas along a marked precipitation and N deposition gradient we will be able to assess the influence of N fluxes to lakes through seasonal monitoring and experimental work. We will combine contemporary ecological experiments (using nutrient bioassays to determine if phytoplankton are nutrient limited, and whether this is through N, P, or co-limitation) with measurements of N content of precipitation (rain and snow). 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 contemporary process studies will be coupled with palaeoecological analyses of lake sediments (diatoms, pigments and stable isotopes of N and C) to establish longer-term trends in SW Greenland. The project has clear relevance for the understanding of drivers of ecological change throughout the Arctic. SW Greenland is typical of many parts of the Arctic both in terms of lake density, precipitation patterns and vegetation. If we establish that lakes in this region have become more productive over the last ~150 years, there are clear implications for large areas of the Arctic which have experienced 20th century 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 C cycling are also important for understanding regional biogeochemical cycling. For example, enhanced N deposition may release bacteria from nutrient limitation, increasing rates of respiration in lakes, thereby contributing to regional CO2 efflux to the atmosphere and hence feedback into the climate system.

现在有明确的证据表明，北极的生态系统正在发生变化。这通常归因于全球变暖，其影响在该地区尤为严重。在这个项目中，我们将测试的假设，长距离大气沉积的氮（N）也是一个重要的驱动力的生态变化在敏感的北极生态系统。湖泊是这些景观的重要组成部分，对区域生态地球化学通量，特别是碳（C）通量至关重要。北极长期生态变化的许多证据来自湖泊沉积物。藻类群落的组成发生了变化，藻类生产力有所提高。尽管许多研究人员将这些变化归因于全球变暖，但温度升高只是人类破坏地球化学循环造成的全球环境变化的一个方面。还有一些其他的因素，一些与气候间接相关，可能会改变湖泊的群落结构;增加风化率，碱度输出和改变地表水pH值。偏远湖泊营养物质的一个重要来源是大气沉积的N。人为固定的N是大于自然率的固定和中断的N循环可以说是一个类似的威胁，以偏远的生态系统气候变化。有证据表明，在北极的高山湖泊和其他地方的初步工作，长期，低水平的沉积氮可能会影响湖泊的生产力和生物结构。我们建议测试的假设，氮沉积是推动生态变化在北极研究湖泊在格陵兰岛西南部的空气温度没有增加，在20世纪世纪，不像北极的大部分地区。我们的初步结果，加上冰芯数据，表明自世纪中期以来，在这一地区的N沉积增加。我们的研究结合了当代生态学、降水监测和古湖沼学。通过仔细选址三个地区沿着一个显着的降水和氮沉积梯度，我们将能够评估的影响，氮通量湖泊通过季节性监测和实验工作。我们将结合联合收割机当代生态实验（使用营养生物测定，以确定浮游植物是否营养有限，这是否是通过N，P，或共同限制）与降水（雨和雪）的N含量的测量。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，这些当代过程的研究将与湖泊沉积物（硅藻，色素和稳定同位素的N和C）的古生态分析相结合，以建立格陵兰岛西南部的长期趋势。该项目对于了解整个北极生态变化的驱动因素具有明显的相关性。格陵兰岛西南部在湖泊密度、降水模式和植被方面都是北极许多地区的典型。如果我们确定该地区的湖泊在过去的150年中变得更加富有成效，那么对于经历了世纪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。养分沉积与碳循环之间可能的相互作用对于了解区域生物地球化学循环也很重要。例如，氮沉降的增加可能会使细菌从营养限制中释放出来，增加湖泊的呼吸速率，从而促进区域性二氧化碳排放到大气中，从而反馈到气候系统中。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Seasonal and Regional Controls of Phytoplankton Production along a Climate Gradient in South-West Greenland During Ice-Cover and Ice-Free Conditions

DOI：
10.1657/aaar0015-003
发表时间：
2016-02
期刊：
Arctic, Antarctic, and Alpine Research
影响因子：
0
作者：
E. Whiteford;Suzanne McGowan;Suzanne McGowan;Christopher D. Barry;N. Anderson
通讯作者：
E. Whiteford;Suzanne McGowan;Suzanne McGowan;Christopher D. Barry;N. Anderson

Complex spatial patterns of limnological variability at seasonal to centennial timescales across a regional climate gradient in SW Greenland.

格陵兰岛西南部区域气候梯度从季节到百年时间尺度的湖泊学变化的复杂空间模式。