Radiometrically determined dates and sedimentation rates for recent sediments in nine North African wetland lakes (the CASSARINA project)

被引：61

作者：

Appleby P.G. ^{[1
]}

Birks H.H. ^{[2
,3
]}

Flower R.J. ^{[3
]}

Rose N. ^{[3
]}

Peglar S.M. ^{[2
]}

Ramdani M. ^{[4
]}

Kraïem M.M. ^{[5
]}

Fathi A.A. ^{[6
]}

机构：

[1] Department of Mathematical Sciences, University of Liverpool, Liverpool L69 3BX

[2] Botanical Institute, University of Bergen, N-5007 Bergen

[3] Environmental Change Research Centre, University College London, London WC1H OAP

[4] Institut Scientifique Zoologie et Ecologie Animale, Charia Ibn Batota, 10106 Rabat

[5] Faculté des Sciences, Dept. de Biologie, Campus Universitaire

[6] Department of Botany, University of El Minia

来源：

Aquatic Ecology | 2001年 / 35卷 / 3-4期

关键词：

!sup]137[!/sup]Cs; !sup]210[!/sup]Pb; Lake sediments; North Africa; Radiometric dating;

D O I：

10.1023/A:1011938522939

中图分类号：

学科分类号：

摘要：

Sediment cores were collected from nine wetland lakes in Morocco, Tunisia and Egypt for the CASSARINA project investigating environmental change in Northern African wetlands. The cores were dated radiometrically by using natural (210Pb) and artificial (137Cs and 241Am) radionuclides. At sites in Morocco and Tunisia with mean annual rainfall totals ranging from 500-1000 mm yr-1, fallout records were generally satisfactory and it was possible to develop independent sediment chronologies based on the radiometric data alone. At the Egyptian sites, rainfall was less than 200 mm yr-1 and fallout records were much less distinct. At these sites the radiometric data could only be used to give an indication of mean sedimentation rates during the past 30-40 years. By using a combination of fallout radionuclide, pollen, and macrofossil stratigraphic records it was however possible to determine a credible sediment chronology spanning the major part of the 20th century. Applying this chronology to records of spheroidal carbonaceous particles (SCP) from the same sediment cores, the onset of significant levels of atmospheric pollution in the Nile Delta is dated in all three cores to the mid 1950s. Results from a number of lakes (Sidi Bou Rhaba, Ichkeul and Korba) revealed high and accelerating siltation rates, threatening their continued existence beyond the next few decades. In contrast, sedimentation rates at all three Nile Delta sites appear to have declined in recent decades, most probably due to the impact of the Nile barrages.

引用

页码：347 / 367

页数：20

共 26 条

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