Shallow pore water sampling in reef sediments

Several new techniques have been developed to allow the geochemical characterization of shallow pore waters in reefs. First, a new method was developed for using non-metallic well-points to sample pore waters from shallow depths (<1 m) in coral reefs with unconsolidated substrates. These PVC well-points can be made faster and at less expense than well-points made of stainless steel. They also eliminate metal contamination and are free from the problems of corrosion in sea water. Additional improvements in sampling techniques maximize the spatial resolution of geochemical gradients and address the problems of atmospheric contamination associated with the sampling of dissolved gases. Data taken from Checker Reef, Oahu, Hawaii, illustrate the application of these methods.