Stable isotopes (δ13C and δ15N) in black coral as new proxies for environmental record

Abstract

Stable isotopes (δ¹³C and δ¹⁵N) in marine ecosystem are useful proxies for environmental record. In this study, a time-series analysis of δ¹³C and δ¹⁵N in two black coral samples collected from off-shore and near-shore environment was performed to investigate variations in climate and environment changes over the last 110 years. The results showed a decreasing trend of δ¹³C in both samples, implying an increase of fossil fuel consumption in modern age - the Suess effect. Meanwhile, a difference in δ¹⁵N between the offshore and nearshore black coral samples can be attributed to atmospheric transport of natural terrigenous source input and local anthropogenic activities. This study demonstrates that black coral has advantages as an environmental proxy compared with other traditional ones, and suggests that δ¹³C and δ¹⁵N in black coral can be used as new proxy indicators for climate changes related to anthropogenic activities.

Keywords: Anthropogenic activities; Black coral; Carbon stable isotope; Climate changes; Nitrogen stable isotope; Suess effect.