Bushaw-Newton, K. and M. A. Moran. In Press. Photochemical formation of biologically available nitrogen from dissolved humic substances in coastal marine systems. Aquatic Microbial Ecology.
    	The photochemical conversion of the nitrogen fraction of
    dissolved humic substances into more biologically available compounds
    was studied in two estuarine sites in the southeastern US.  Marine humic
    substances were isolated using an XAD-8 resin and used in bacterial
    bioassays and chemical studies.  The bioassays demonstrated that humic
    substances irradiated with natural sunlight supported enhanced bacterial
    growth, measured as cell accumulation and protein production, due to
    increased availability of both the carbon and nitrogen components. 
    Chemical analyses demonstrated the photoproduction of ammonium and
    dissolved primary amines from the coastal humic substances.  The total
    biologically available nitrogen (ammonium, dissolved primary amines, and
    other unidentified compounds) formed during a day-long irradiation at
    natural solar radiation levels accounted for about 6% of the original
    nitrogen associated with the humic substances.  Photochemical
    modification of marine humic substances may provide a source of labile
    nitrogen to estuarine and coastal ecosystems that has not previously
    been considered.