Investigation of Oceanic Organic Chemistry Using State-of-the-Art Laser BasedAnalytical Techniques

摘要

The fluorescence of global seawater has been investigated using a sensitive laser-induced fluorometry system. In surface seawater, fluorescence is low due to photochemical bleaching. Fluorescence intensity increases with increasing depth in the oceans to about 500 to 1000 m; below this depth, seawater fluorescence is generally constant. Sediment porewaters are much more fluorescent than the overlaying seawater. Both porewater fluorescence, and the dissolved organic carbon (DOC) concentration, increase with depth in the sediment. Fluorescence of porewaters can thus be used to provide an estimate of the DOC content. Because of the higher fluorescence in porewaters in comparison of seawater, fluorescence provides a means of estimating the amount of DOC diffusing out of sediments into seawater. The fluorescence measurements indicate that this source of DOC is only a minor contributor to the oceanic DOC budget. (AN).