COLLECTION, ANALYSIS AND VARIATION OF NUTRIENTS IN ESTUARINE PORE WATER

A series of field experiments were performed using in situ porous Teflon samplers to determine the nutrient concentrations of anoxic pore waters in estuarine sediments. A method is described where pore water may be collected, stored and analyzed in an inert atmosphere. Multiple samples may be collected over long time periods without disturbing the sediment. High variability of nutrient levels within a 1 m2 plot of a subtidal mud flat were detected. The variation of ammonium (NH4+) reactive phosphate (RP) and silicate (SiO3) in pore water were 34.3, 30.7 and 40%, respectively, for 4 samplers placed at the same depth in this 1 m2 area, while sampler variability under laboratory conditions was 5.0, 7.0 and 0.3% for these nutrients, respectively.