Paleolimnology and Environmental Change

古湖泊学和环境变化

• 批准号: RGPIN-2022-04030
• 负责人: Cumming, Brian
• 金额: $ 3.13万
• 依托单位: Queen's University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=745665
• 关键词: Paleolimnology; Environmental; Change

The proposed research will contribute to advancing our understanding of the impacts of acidic deposition, climate change and their interactions on lakes. My research program is on paleolimnology and long-term environmental change in lakes and rivers. Paleolimnology is the interdisciplinary science that uses the physical, chemical, and biological information preserved in lake sediments to understand how lakes change over time. Long-term perspectives are essential to understand environmental change. In the 1980s, lake sediment cores from Adirondack lakes showed that the timing and rate of lake acidification was strongly associated with acidic deposition, and that between 25-35% of Adirondack lakes acidified since pre-industrial times. These conclusions supported the 1990 amendment of the Clean Air Act, and reductions in SO2 and NOX emissions continued, resulting in the `chemical' recovery of many Adirondack lakes. Recent increases in water colour (related to dissolved organic carbon, DOC) has been associated with recovery, but could also be related to recent warming and higher rainfall. Biological recovery following chemical recovery is complex because in any individual lake, there are many possible drivers related to both regional and local factors. This study uses lake sediments from groups of morphologically similar lakes, all with undisturbed catchments and lakes, in both the Adirondacks and northwest Ontario. Both regions have experienced recent warming and general increases in precipitation. However, northwest Ontario has not experienced high loads of acidic precipitation, whereas the sulphate deposition in the Adirondack reached over >30 kg/ha/year in the 1970s, before decreasing by over 80% by 2020. The goal of this study is to understand how changes in algal (pigments, diatoms, and scaled chrysophytes) and invertebrate (cladocerans and chironomids) assemblages, since pre-industrial times in both regions, are related to patterns in S and N deposition, spectrally inferred patterns of DOC from the sediment cores, and changes in temperature and precipitation.  This paleolimnological study will be based on biological changes in a priori defined groups of lakes sampled at a sub-decadal resolution since pre-industrial times. Two distinct groups of Adirondack lakes include: a) lakes that were chronically acidic in the late 1980s; and b) Adirondack lakes with a higher pH that did not acidify but may have experienced changes in algal and invertebrate assemblages associated with decreases in DOC linked to the acidic deposition. Lakes in northwest Ontario will be the final group, providing for biological changes associated with changes in climate, and smaller changes in DOC and acidic deposition; a varved sediment record will provide information on algal seasonality, and a higher resolution record of change for northwest Ontario. Understanding the major environmental drivers of biological changes is important for effective lake management.

拟议的研究将有助于增进我们对酸沉积、气候变化及其相互作用对湖泊的影响的理解。我的研究项目是古湖沼学和湖泊和河流的长期环境变化。古湖学是一门交叉学科，它利用保存在湖泊沉积物中的物理、化学和生物信息来了解湖泊如何随着时间的推移而变化。长期视角对于理解环境变化至关重要。20世纪80年代，阿迪朗达克湖泊的沉积物岩心表明，湖泊酸化的时间和速度与酸沉积密切相关，自前工业时代以来，25%-35%的阿迪朗达克湖泊发生了酸化。这些结论支持1990年对《清洁空气法》的修正，二氧化硫和氮氧化物排放量的减少继续，导致许多阿迪朗达克湖的“化学”恢复。最近水色的增加(与溶解有机碳有关)与复苏有关，但也可能与最近变暖和降雨量增加有关。化学恢复后的生物恢复是复杂的，因为在任何一个湖泊中，都有许多可能的驱动因素与区域和当地因素有关。这项研究使用了来自阿迪朗达克山脉和安大略省西北部的一组形态相似的湖泊的湖泊沉积物，这些湖泊都有未受干扰的集水区和湖泊。这两个地区都经历了最近的变暖和降水的普遍增加。然而，安大略省西北部并没有经历高负荷的酸性降水，而阿迪朗达克地区的硫酸盐沉降量在20世纪70年代达到了30公斤/公顷/年以上，到2020年下降了80%以上。这项研究的目的是了解这两个地区自工业化前以来藻类(色素、硅藻和鳞片黄藻)和无脊椎动物(枝角类和摇蚊)组合的变化如何与S和N沉积的模式、从沉积物岩芯中光谱推断的DOC模式以及温度和降水的变化有关。这项古水文学研究将基于自工业化前以来以亚十年分辨率采样的预先确定的湖泊组的生物变化。两类不同的阿迪朗达克湖包括：a)20世纪80年代末长期酸性的湖泊；b)pH较高的阿迪朗达克湖，这些湖泊没有酸化，但可能经历了藻类和无脊椎动物组合的变化，这与与酸沉积有关的DOC减少有关。安大略省西北部的湖泊将是最后一组，提供与气候变化相关的生物变化，以及DOC和酸沉积的较小变化；不同的沉积物记录将提供有关藻类季节性的信息，并提供安大略省西北部更高分辨率的变化记录。了解生物变化的主要环境驱动因素对于有效的湖泊管理非常重要。