Distribution of sedimentary phosphorus in Gulf of Mexico estuaries

Abstract

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 marine environmental quality; NOAA/OMA, Rockville, MD, USA). These have been 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 μmol/g and averages 11·3 μmol/g. Higher values were found in Louisiana estuaries 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 leachable species and is higher in samples from higher salinity sites. Previous unpublished data by one of the authors (D.A.) on solid phase and pore water phosphate from 18 cores collected on the Mississippi River Delta, are reported for the first time here. Low dissolved phosphate (< 5 μM/liter) was found at the surface of several cores but values at 1 m depth were mostly much higher (up to 145 μM/liter). Pore water phosphate gave a significant positive correlation with solid phase inorganic phosphorus, but a poor correlation with solid organic phosphorus, showing the importance of inorganic reactions in controlling dissolved PO 4 in pore water.