DISTRIBUTION OF SEDIMENTARY PHOSPHORUS IN GULF-OF-MEXICO ESTUARIES

Sediment samples were collected from all the major bays and estuaries along the US Gulf of Mexico Coastline in 1986-1988 by the NOAA NS & T Program (NOAA (1989), The National Status and Trends Program for marin e environmental quality; NOAA/OMA, Rockville, MD, USA). These have bee n analyzed for total phosphorus as well as leachable Al-P, Ca-P and Fe -P. Total phosphorus concentration ranges from 1.8 to 45.9 mumol/g and averages 11.3 mumol/g. Higher values were found in Louisiana estuarie s than in those in Texas but the highest values occur in the phosphate rock mining region of southern Florida. Ca-P is the most abundant lea chable species and is higher in samples from higher salinity sites. Pr evious unpublished data by one of the authors (D.A.) on solid phase an d pore water phosphate from 18 cores collected on the Mississippi Rive r Delta, are reported for the first time here. Low dissolved phosphate (< 5 muM/liter) was found at the surface of several cores but values at 1 m depth were mostly much higher (up to 145 muM/liter). Pore water phosphate gave a significant positive correlation with solid phase in organic phosphorus, but a poor correlation with solid organic phosphor us, showing the importance of inorganic reactions in controlling disso lved PO4 in pore water.