Geochemistry of Marine Humic Compounds

Some 90 years ago, the first information on the occurrence of dissolved organic matter in sea water was published. For 50 years after that reve lation, little progress was made in identifying these dissolved "yellow substances." In the 1950s and 1960s, a few chemical oceanographers identified some specific dissolved organic compounds, but few of these pioneers fully appreciated their significance in terms of biological inter actions, metal chelation, or interactions with sedimentary material. When Mohammed Rashid began his work on marine humic compounds in the mid-1960s, he was one of only five scientists who had specifically designed their studies toward understanding the nature of these complex materials. Over the next decade, Dr. Rashid directed his research toward characterization of humic and fulvic compounds in the marine environ ment, the influence of humic substances on the growth of marine phy toplankton, the role of organic matter in complexing metals in sea water and marine sediments, the interaction between humic substances and clay minerals in marine environments, and the influence of organic matter on the geotechnical properties of marine sediments. As if the many papers produced from these scientific investigations were not sufficient, Dr.