Historical trends of terrigenous organic carbon transported by the Yangtze River
(Changjiang)
Yu Hao and Wu Ying
State Oceanic Administration of China, Qingdao, Shandong, China, PR
E-mail:
yuhao_cn78@yahoo.com
In order to reconstruct the history of terrestrial discharge and human activities in the
past 70 years, sediment core samples collected from the Yangtze River estuary were
analyzed through lignin-phenols, pigments and stable isotopic (δ13C and δ15N)
analysis. The variation of concentration and degradation of lignin phenols in
sediments is separated in three depths, with higher concentration and lower
degradation in the first 80 cm from the surface, lower concentration and higher
degradation in the middle of the core (80cm ~ 170cm) and higher concentration and
lower degradation from 170cm to 270cm, which are related to different periods
affected by human activities respectively. Moreover, the flooding events of the
Yangtze River in 1954 and 1998 also could be recognized through the sediment core
samples. After the mid-1980s, the sediment load of the Yangtze River has become an
essential factor in affecting the discharge of terrigenous organic carbon, due to the
building of dams. However, when compared with other research, owing to
complicated sediment burial speeds and hydrodynamic conditions, as well as
influences brought by vertical mixing in the Yangtze estuary, the effect of terrigenous
organic carbon to the carbon cycle in this region should be further studied.