ABSTRACT

A solid-phase extraction technique has been examined for pretreatment of colorimetric determination of soluble reactive phosphorus (SRP) in sediment extracts. The SRP was effectively collected as a molybdophosphoric acid complex by a cartridge column packed with polystyrene divinylbenzen resin. The complex adsorbed on the resin was eluted with a small aliquot (<5 ml) of 0.5 M NaOH solution. The recovered SRP was then determined by the standard molybdenum blue method. Compared with the solvent-extraction technique which has been generally used by previous workers, the present method consists of much easier procedures, and precision and recovery of this method are sufficiently high. The method was then applied for the determination of iron-bound P (Fe-P) in sediment samples from the Tamagawa Estuary. The results suggest that Fe-P in sediments is an important source of P in estuarine and coastal ecosystems through releasing phosphate to estuarine water with increasing salinity.