论泥炭纤维素碳同位素组成作为东亚季风强度变化代用指标的可行性:吉林3个临近发育的泥炭地泥炭剖面的横向比对

降雨量通常与东亚季风强度成正比,而植物纤维素碳同位素组成又与降雨量成反比,因此泥炭纤维素碳同位素比值通常作为东亚季风强度变化的代用指标。由于季风影响的广泛性和区域性,临近发育的泥炭地植物纤维素碳同位素序列应该高度相关。为了验证这种假设,我们系统比较了吉林3处泥炭地3个泥炭剖面苔草纤维素2000年来的碳同位素序列。14 C时标控制的3个序列不呈现有意义的相关关系。不同时段,如过去500年、1000年、1500年和2000年来序列的长期趋势也不相关,序列中包含的周期完全不同。这些事实说明3处剖面苔草纤维素碳同位素比值记录的是当地性的而不是区域性的气候或环境信号,将泥炭纤维素碳同位素比值作为东亚季风强度变化的代用指标的合理性值得怀疑。

On the Reasonability of Using Carbon Isotopic Composition of Peat Cellulose as a Proxy for the East Asian Monsoon Intensity: A Comparison of Three Peat Profiles in Three Peatlands Formed Contiguously in Jilin, NE China

Precipitation is generally positively correlated with the East Asian monsoon intensity while the carbon isotopic composition of plant cellulose is negatively related with rainfall amount. Hence, the carbon isotopic ratios of peat cellulose have been used as a proxy for the East Asian monsoon changes. Due to the universality and regionality of monsoon influence, carbon isotopic series from different peatlands formed contiguously should be highly correlated. To test this hypothesis, we have made a comparison of three time series in carbon isotope ratios of sedge cellulose extracted from three peat profiles obtained in three different sites in Jilin, NE China. These series covered past 2000 years by ¹⁴C dating. There is no significant correlation between any two of the three series on the ¹⁴C time scale. No common cycles are present in these three series. Moreover, the long-term trends of these time series are quite different for the periods of past 500 years, 1000 years, 1500 years and 2000 years. These facts suggest that the carbon isotopic ratios of peat cellulose could probably record only local, but not regional climatic or environmental signals. Thus, it should be still open to discussion whether or not the carbon isotopic ratios of peat cellulose could be used as a proxy for the East Asian monsoon intensity.