Microfossil study of Holocene aridity in the Great Lakes

五大湖全新世干旱的微化石研究

• 批准号: 121633-2006
• 负责人: McCarthy, Francine
• 金额: $ 1.05万
• 依托单位: Brock University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2008
• 资助国家: 加拿大
• 起止时间: 2008-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=391198
• 关键词: Microfossil; study; Holocene; aridity; Great

The Great Lakes Region is one of the most heavily populated in North America. A substantial fall in lake level would have a significant socioeconomic impact on this region, as it would affect navigation, water quality, aquatic and coastal ecosystems, and recreational use. There is evidence of a lowstand perhaps as much as 80 m below present lake levels in Georgian Bay in the not very distant past (around 8000 years ago), for instance, which appear to have been incorporated in the legends of the First Nations people of the region and passed down through the millenia. Because the onset of aridity is rapid, even in human time frames, and because agriculture and potable water supplies are greatly impacted (as evidenced in the "Dust Bowl" of the 1930's and the more recent near-disappearance of the Aral Sea), it is important to know the natural variability of precipitation and moisture availability in the Great Lakes region in order to anticipate the future and avoid unpleasant surprises. The fossil record of Great Lakes, and of small lakes in their drainage basins, record changes in aridity and lake level since the ice sheets retreated. Microfossils (pollen, and the remains of bottom-dwelling and planktonic lake-dwelling microorganisms) will be used to reconstruct paleoenvironments, and these data will be provided to modelers to assist them in producing accurate models of climate and lake level for this region. The improved understanding of the climate system, and how it produced (and responded to) arid conditions will be of global importance, since cold, arid conditions have been noted throughout the Northern Hemisphere around 8000 years ago.

五大湖地区是北美人口最稠密的地区之一。湖泊水位的大幅下降将对该地区产生重大的社会经济影响，因为它将影响航行、水质、水生和沿海生态系统以及娱乐用途。例如，有证据表明，在不久的过去（大约8000年前），格鲁吉亚湾的湖泊水位可能比现在低80米，这似乎已经被纳入该地区第一民族的传说中，并通过千年流传下来。由于干旱的开始是迅速的，即使在人类的时间框架内，因为农业和饮用水供应受到很大影响（如20世纪30年代的“沙尘暴”和最近咸海的几乎消失），重要的是要知道五大湖地区降水和水分的自然变化，以预测未来，避免不愉快的惊喜。五大湖及其流域中的小湖的化石记录记录了自冰盖退缩以来干旱和湖面的变化。微体化石（花粉、底栖和水生湖泊微生物的遗骸）将用于重建古环境，这些数据将提供给建模人员，以协助他们制作该地区气候和湖泊水位的准确模型。对气候系统及其如何产生（和应对）干旱条件的更好理解将具有全球重要性，因为大约8000年前，整个北方半球都出现了寒冷、干旱的条件。