Multi-decadal Records of Ocean Acidification and Toxic Heavy Metal Pollution in Coral Cores from Oahu, Hawaii

Monitoring of the physiological/ecological response of marine calcifying organisms to the combination of lower pH and toxic metal pollutants (e.g. Cu and Sn from boat anti-fouling paints) into the oceans requires detailed knowledge of the rates and spatial distribution of ocean acidification (OA) and trace metal composition over time. Yet, measurement of metal concentrations and carbonate system parameters in the modern ocean from seawater bottle data is patchy (e.g. CDIAC/WOCE Carbon Data; http://cdiac.ornl.gov) and there remain few long-term surface water pH monitoring stations; the two longest continuous records of ocean pH extend back less than 30 years (Bermuda - BATS, 31°40'N, 64°10'W; Hawaii - HOTs, 22°45'N, 158°00'W). Much attention has therefore been focused on trace metal and ocean carbonate system proxy development to allow reconstruction of seawater metal content and pH in the past. Of particular promise is the boron isotope (δ11B) pH-proxy measured in marine calcifying organisms such as coral that can be cored enabling multi-decadal, annual-resolution, records of trace element incorporation and seawater pH to be generated. Here we present continuous Cu/Ca and Sn/Ca records in addition to δ11B data from three coral cores of Porites lutea. collected from waters proximal to Oahu, Hawaii. The diagenetic integrity of samples is verified using X-ray diffraction to assess the degree of calcite replacement. These cores reach a maximum depth of 80 cm and represent approximately 80 years of coral growth and seawater chemistry.