DOI: 10.1016/j.palaeo.2013.01.008
论文题名: Spatial and temporal variability in sedimentological and geochemical properties of sediments from an anoxic crater lake in West Africa: Implications for paleoenvironmental reconstructions
作者: Shanahan T.M. ; McKay N. ; Overpeck J.T. ; Peck J.A. ; Scholz C. ; Heil C.W. ; King J.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2013
卷: 374 起始页码: 96
结束页码: 109
语种: 英语
英文关键词: Elemental composition
; Isotope
; Lake Bosumtwi
; Lake level
; Paleoclimate
; Paleolimnology
; Surface sediment
英文摘要: The physical, inorganic and organic geochemical and stable isotopic characteristics of lacustrine sediments can provide valuable insights into past environmental changes, provided that the environmental controls on these characteristics are well understood. In the present study, a set of 155 modern vegetation, catchment soil, river sediments and lake surface sediment samples are used to characterize the spatial patterns of TOC, TN, C/N ratios, stable isotope, major element, and particle size distributions within Lake Bosumtwi, a meromictic crater lake in West Africa. Spatial variations in sediment characteristics are strongly correlated with depth and distance from shore, reflecting the dominant influence of lake level on the relative proportions of littoral and pelagic depositional systems and their impact on the physical and geochemical properties of lacustrine sediments. This is supported by a principal component analysis, which indicates that 65% of the variance in the dataset is explained by depth-related variability in the sedimentary components. Variations in sedimentary organic matter reflect the combined influences of productivity, preservation and the relative proportions of aquatic and terrestrial organic matter sources. Grain size and Si content are dominantly influenced by the delivery of clastic materials from the watershed to the lake, whereas Fe and Ca appear to be most strongly influenced by the delivery of reduced metals and nutrients from the anoxic hypolimnion to the surface. With the exception of grain size, all of the sediment parameters record synchronous century-scale variability over the past ~2.5ka, consistent with independent evidence for changes in lake level. However, the magnitude of changes in sediment characteristics differs, reflecting different sensitivities to water depth, particularly in the deepest part of the lake basin where the sediment cores were collected. However, even the parameters with the most linear and strongly significant relationships with depth (e.g., TOC, TN) significantly overestimate the magnitude of lake level changes, suggesting that these parameters may be best suited to qualitative paleolake level reconstructions. Over the last 2 centuries, changes in C/N and δ13C became decoupled from the other geochemical proxies and the inferred rise in lake level. We hypothesize that this reflects the influence of anthropogenic land use change on the composition of terrestrial organic matter sources contributing to the lake. This result highlights the potential difficulties in reconstructing past environmental changes from indirect proxy measurements when those proxies may be subject to multiple varying controls. © 2013 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/69795
Appears in Collections: 过去全球变化的重建
There are no files associated with this item.
作者单位: Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78713, United States; Department of Geosciences, University of Arizona, Tucson, AZ 85721, United States; Institute of the Environment, University of Arizona, Tucson, AZ 85721, United States; Department of Geology and Environmental Science, University of Akron, Akron, OH 44325, United States; Department of Earth Sciences, Syracuse University, Syracuse, NY 13244, United States; Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, United States
Recommended Citation:
Shanahan T.M.,McKay N.,Overpeck J.T.,et al. Spatial and temporal variability in sedimentological and geochemical properties of sediments from an anoxic crater lake in West Africa: Implications for paleoenvironmental reconstructions[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2013-01-01,374