Catchment environmental change over the 20th Century recorded by sedimentary leaf wax n-alkane δ13C off the Pearl River estuary
The compound-specific stable carbon isotope compositions ( δ 13 C) of leaf wax n -alkanes from two short sediment cores recovered off the Pearl River estuary (PRE) were analyzed to check for their capability of indicating decadal scale catchment environmental change. Sedimentary long-chain n -alkane...
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Published in | Science China. Earth sciences Vol. 59; no. 5; pp. 975 - 980 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Beijing
Science China Press
2016
|
Subjects | |
Online Access | Get full text |
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Summary: | The compound-specific stable carbon isotope compositions (
δ
13
C) of leaf wax
n
-alkanes from two short sediment cores recovered off the Pearl River estuary (PRE) were analyzed to check for their capability of indicating decadal scale catchment environmental change. Sedimentary long-chain
n
-alkanes exhibited an odd-over-even predominance, with a maximum at
n
-C
29
or
n
-C
31
, indicating their leaf wax origin was from vascular plants. The
δ
13
C values of C
29
and C
31
n
-alkane in all the sediment samples were in the range of -28.8‰ to -31.2‰, consistent with the C
3
plant-dominated vegetation in the Pearl River catchments. The time series of
δ
13
C records from the two cores were comparable and displayed a decreasing trend from the early 20th century to the end of the 1970s, followed by a reversal in that change leading to continued increase for ca. 15 years. After being corrected for the effect of atmospheric CO
2
rise and
δ
13
C
atm
decline, the
δ
13
C
29
records largely retained their raw changing pattern; the post-1980 increase being more conspicuous. The slightly decreasing trend in corrected
δ
13
C records before around 1980 may have been caused by an increase in precipitation, whereas the subsequent increase of
δ
13
C is likely associated with the observed dry climate and/or intensive anthropogenic deforestation. Our results thus demonstrate that leaf wax
n
-alkanes buried in the sediments off the PRE may well reflect change in the regional climate and/or human activity in the river catchments over the past century. |
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ISSN: | 1674-7313 1869-1897 |
DOI: | 10.1007/s11430-015-5206-3 |