科研之友
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摘要
An integrated pollen-analytical and geochemical study is presented from Qinngua Kangilleq, southwest Greenland. This site was formerly one of the largest farms in the Eastern Settlement of Norse Greenland. The study is the first to determine what link, if any, exists between Norse landnam (early settlement), vegetation change, soil erosion, climate change and peat geochemistry. The data suggest that fluxes in lithogenic elements supplied to a peat column by terrestrial sources and atmospheric deposition were coupled to the pattern of local Norse settlement beginning similar to cal. AD 1020. A severe phase of soil erosion is indicated which is coincident with the landnam horizon. This may represent proxy evidence for the stripping of turf for the construction of turf-and-stone buildings at the farm. Radiocarbon dates suggest the presence of a hiatus in the sediment column spanning similar to cal. AD 1380-1950. Following the recommencement of sediment accumulation, the geochemical data indicate a critical change in site conditions which may be consistent with the well-known change in Northern Hemisphere atmospheric circulation that started between c. AD 1400 and 1420. Bromine (Br) and chlorine (Cl) concentrations are demonstrably higher in the sediments dating to the 20th century relative to the pre-15th century deposits. Rising halogen concentrations at Qinngua appear to be correlated with increased levels of Na(+) (sea salt sodium) precipitation in the GISP2 ice core which earlier studies have interpreted as indicative of increased North Atlantic storminess.
- 出版日期2010-9-1
