Annual variation of Ba/Ca and Mn/Ca ratios in Porite coral from eastern Hainan
Island and their environmental implication
Qiaowen Jiang2, Zhimin Cao2, Daoru Wang3, Yuanchao Li3, Zhongjie Wu3 and Jianyu
Ni1
1Second
Institute of Oceanography, SOA, Hangzhou, PR China. E-mail: jianyuni@sio.org.cn
of Marine and Earth Sciences, Ocean University of China, Qindao, PR China
3
Hainan Ocean and Fishery Sciences, Haikou, PR China
2School
The annual variations in Ba/Ca and Mn/Ca ratios of the Porties coral from eastern
Hainan Island have been studied using inductively coupled plasma-atomic emission
spectrometry (ICP-AES). The analysis results show that the skeletal Ba/Ca ratio
varied from 3.120 to 10.064 μmol/mol, with an average of 5.256 μmol/mol. The
maximum value occurred in 1944, and the minimum occurred in 1903. The Mn/Ca
ratio changed between 0.206 and 5.708 μmol/mol, with an average of 1.234 μmol/mol,
observing three Mn/Ca ratio maxima since 1932 and consistent with the strong
rainfalls caused by typhoons. The results exhibit seasonal variations of the coralline
Ba/Ca and Mn/Ca ratios with higher Ba/Ca and Mn/Ca ratios in the rainy season
(from May to October) and lower ratios in the dry season (from November to April).
Comparing the results to the instrumentally measured hydrologic data shows that in
the past 100 years skeletal Ba/Ca and Mn/Ca ratios of the Porties coral from eastern
Hainan Island mainly reflected the influence of terrigenous inputs and changes in
rainfall, while the response to upwelling was limited.