Publication Date:
2018-08-17
Description:
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 δ15N in coral skeleton organic material (CS-δ15N) 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 δ15N 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 δ15N 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. ©2018. American Geophysical Union. All Rights Reserved.
Print ISSN:
0094-8276
Electronic ISSN:
1944-8007
Topics:
Geosciences
,
Physics
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