Dynamics of amino acids in the conditioning film developed on glass panels immersed in the surface seawaters of Dona Paula Bay

The conditioning film developed on glass panels immersed in surface seawater over a period of 24 h was analysed for total organic carbon (OC), total organic nitrogen (ON), and total hydrolyzable amino acid (THAA) concentrations and composition. The concentrations of C and N and THAA increased, whereas the C/N ratio decreased over the period of immersion. The amino acid-C and N accounted for 3.7-6.7% and 10.3-65.3% of OC and ON, respectively. The relative contribution of glycine plus threonine and serine to the total amino acids decreased while that of valine, phenylalanine, isoleucine and leucine increased over the period of immersion. Principal component analysis (PCA) based on mole% amino acid composition showed that the degradation indices (DI) for the conditioning film organic matter increased over the period of immersion. A high C/N ratio, a low %THAA-C, % THAA-N and DI values and the abundance of glycine plus threonine and serine in the conditioning film organic matter during the first few hours following immersion imply that the adsorbed organic matter was mostly derived from degraded organic matter.