资源环境科技发展态势分析平台

Anthropogenic activity on tropical islands has been linked with nitrogen (N) contamination of groundwater and subsequent coral reef health decline. However, identifying the temporal patterns of groundwater N contamination has proven difficult because of an absence of long-term records. Here we use delta N-15 in coral skeleton organic material (CS-delta N-15) to reconstruct historical patterns of groundwater N discharge to a coral reef system at Rarotonga in the Cook Islands in the South Pacific. Analysis of coral skeletal material dating back to 1880 CE clearly shows that the delta N-15 of N available in the reef environment around Rarotonga increased between 1980 and 2000. We propose that rapid agricultural development in the Cook Islands between 1960 and 1985 increased aquifer N concentrations leading to the elevated delta N-15 of groundwater NO3-. The discharge of this groundwater N appears to have continued for at least 15 years after the cessation of the agricultural boom. This has important implications for the management of groundwater contamination on low-lying tropical islands.