Diatom-based models for inferring past water chemistry in western Ugandan crater lakes
Diatom-based models for inferring past water chemistry in western Ugandan crater lakes
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DOI：
10.1007/s10933-012-9609-2
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发表时间：
2012-06
影响因子：
2.1
通讯作者：
Keely Mills;D. Ryves
中科院分区：
文献类型：
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作者：
Keely Mills;D. Ryves
硅藻表面沉积物样品和相应的水化学收集了56个湖泊在乌干达西部的自然电导率梯度（反映了有效水分的区域气候梯度），探讨控制硅藻分布的因素。在这里，我们从这些火山口湖泊中开发了一个区域训练集，以测试这种方法的假设，通过提供更合适和更接近的类似物，可以提高古电导率重建的准确性，因此与更大的训练集相比，这些湖泊系统的环境推断。我们将此输出与基于更大但地理和湖沼学上不同的训练集的模型进行比较，使用欧洲硅藻数据库计划（EDDI）数据库。利用典范对应分析（CCA）和部分CCA探讨了水化学与硅藻分布的关系。方差分配表明，电导率占一个显着的和独立的一部分，这种变化。开发了电导率的传递函数（rjack2= 0.74）。预测误差，估计使用折刀，是低的电导率模型（0.256 log10单位）。由此产生的模型被应用到从湖卡森达，乌干达西部的沉积序列。使用乌干达火山口湖训练集和东非训练集（EDDI）的电导率重建的比较突出了一些关键硅藻类群的最优值的差异，这导致重建值的差异，并可能导致对化石记录的误解。这项研究突出了如何传递函数的基础上，如EDDI泛非洲模型应使用的大陆规模的湖泊数据集，并可能从区域训练集获得的好处。
Diatom surface sediment samples and corresponding water chemistry were collected from 56 lakes across a natural conductivity gradient in western Uganda (reflecting a regional climatic gradient of effective moisture) to explore factors controlling diatom distribution. Here we develop a regional training set from these crater lakes to test the hypothesis that this approach, by providing more appropriate and closer analogues, can improve the accuracy of palaeo-conductivity reconstructions, and so environmental inferences in these lake systems compared to larger training sets. We compare this output to models based on larger, but geographically and limnologically diverse training sets, using the European Diatom Database Initiative (EDDI) database. The relationships between water chemistry and diatom distributions were explored using canonical correspondence analysis (CCA) and partial CCA. Variance partitioning indicated that conductivity accounted for a significant and independent portion of this variation. A transfer function was developed for conductivity (rjack2= 0.74). Prediction errors, estimated using jack-knifing, are low for the conductivity model (0.256 log10units). The resulting model was applied to a sedimentary sequence from Lake Kasenda, western Uganda. Comparison of conductivity reconstructions using the Ugandan crater lake training set and the East Africa training set (EDDI) highlighted a number of differences in the optima of key diatom taxa, which lead to differences in reconstructed values and could lead to misinterpretation of the fossil record. This study highlights issues of how far transfer functions based on continental-scale lake datasets such as the EDDI pan-African models should be used and the benefits that may be obtained from regional training sets.