Physical and chemical predictors of diatom dissolution in freshwater and saline lake sediments in North America and West Greenland
Physical and chemical predictors of diatom dissolution in freshwater and saline lake sediments in North America and West Greenland
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DOI：
10.4319/lo.2006.51.3.1355
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发表时间：
2006-05
影响因子：
4.5
通讯作者：
D. Ryves;R. Battarbee;S. Juggins;S. Fritz;N. Anderson
中科院分区：
文献类型：
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作者：
D. Ryves;R. Battarbee;S. Juggins;S. Fritz;N. Anderson
在常规硅藻分析中，使用形态学方法对来自北部大平原（NGP; n = 64）和西格陵兰岛（n = 40）的两个区域湖泊数据集的地表沉积物样品中的硅藻溶解进行了评估。推导了两个溶解度指标来参数化硅藻的溶解度，并在盲测中对两个分析指标进行了比较，结果显示出良好的对应关系，且与硅藻破碎度密切相关。我们利用多元方法和逻辑回归模型探讨了水化学和湖泊物理参数（包括溶解度）与两个湖区溶解度之间的关系。盐度是西格陵兰岛溶解的唯一重要预测因子，但盐度、碳酸盐浓度（[CO32−]）和溶解度是NGP的重要预测因子。湖泊参数解释了40-59%两个地区溶蚀指数的变化。溶解指数方法应用于魔鬼湖（北达科他州）的短沉积物序列，其中硅藻推断的盐度推断可以与20世纪盐度波动的历史记录进行比较。古盐度估计的绝对误差与硅藻溶解密切相关，在11个保存较差的样品中，有8个样品的盐度被高估。保存状态似乎限制了该地点推断的古盐度的可靠性，也可能影响其他地方基于硅藻的古环境推断的质量（包括生物成因二氧化硅的估计），这些地方的保存状态通常没有明确考虑。
Diatom dissolution in surface sediment samples from two regional lake datasets in the Northern Great Plains (NGP; n = 64) and West Greenland (n = 40) is assessed using a morphological approach categorizing valves during routine diatom analysis. Two dissolution indices are derived to parameterize diatom dissolution, and, when compared between two analysts in a blind test, show good correspondence and are closely correlated to diatom fragmentation. We explore the relationships between hydrochemical and physical lake parameters (including meromixis) on dissolution within both lake regions using multivariate methods and modeled with logistic regression. Salinity is the sole significant predictor of dissolution in West Greenland but salinity, carbonate concentration ([CO32−]) and meromixis are significant predictors in the NGP. Limnological parameters explain 40–59% of variation in dissolution in both regions for both dissolution indices. The dissolution index methodology is applied to a short sediment sequence from Devils Lake (North Dakota), where diatom‐inferred salinity inferences can be compared with a historical record of salinity fluctuations over the 20th century. Absolute errors in paleosalinity estimates are strongly correlated with diatom dissolution, with salinity overestimated in 8 out of 11 poorly preserved samples. Preservation does appear to constrain the reliability of the inferred paleosalinity at this site and may also affect the quality of diatom‐based paleoenvironmental inferences elsewhere (including estimates of biogenic silica), where preservation state is often not explicitly considered.