Paleolimnology and Environmental Change

拟议的研究将有助于推进我们对酸性沉积、气候变化及其相互作用对湖泊影响的理解。我的研究项目是古湖沼学和湖泊和河流的长期环境变化。古湖沼学是一门跨学科的科学，它利用湖泊沉积物中保存的物理、化学和生物信息来了解湖泊如何随时间变化。长期的观点对于理解环境变化至关重要。20世纪80年代，阿迪朗达克湖的沉积物岩心显示，湖泊酸化的时间和速度与酸性沉积密切相关，自工业化前时代以来，阿迪朗达克湖的25-35%酸化。这些结论支持了1990年《清洁空气法》的修正案，二氧化硫和氮氧化物排放量的减少继续进行，导致许多阿迪朗达克湖的“化学”恢复。最近的水色增加（与溶解有机碳有关）与恢复有关，但也可能与最近的变暖和降雨量增加有关。 化学品回收后的生物回收是复杂的，因为在任何一个湖泊中，都有许多与区域和当地因素有关的可能驱动因素。本研究使用的湖泊沉积物组的形态相似的湖泊，所有未受干扰的集水区和湖泊，在阿迪朗达克山脉和西北安大略。这两个地区最近都经历了变暖和降水量普遍增加。然而，安大略西北部没有经历过高负荷的酸性降水，而阿迪朗达克的硫酸盐沉积在20世纪70年代达到超过30公斤/公顷/年，然后到2020年减少80%以上。本研究的目的是了解藻类（色素，硅藻，和规模的金藻）和无脊椎动物（枝角类和摇蚊）组合的变化，因为在这两个地区的工业化前的时间，与S和N的沉积模式，光谱推断模式DOC从沉积物芯，温度和降水的变化。 这项古湖沼学研究将以前工业时代以来以亚十年分辨率采样的先验定义湖泊群的生物变化为基础。阿迪朗达克湖的两个不同的群体包括：a）在20世纪80年代后期长期呈酸性的湖泊;和B）阿迪朗达克湖具有较高的pH值，没有酸化，但可能经历了藻类和无脊椎动物组合的变化与DOC的减少与酸性沉积。安大略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，DOC和酸性沉积物的变化较小;一个多纹沉积物记录将提供藻类季节性的信息，并为安大略西北部提供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至关重要。

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.