Comparison of pore water sampling techniques for trace metals

Four methods of sediment pore water collection—centrifugation, squeezing, vacuum filtration, and dialysis—have been compared using an artificial sediment system containing cadmium. It was found that vacuum filtration and squeezing gave cadmium concentrations much higher than expected. Centrifugation and dialysis gave similar, but slightly lower than expected concentrations. However, it is recommended that centrifugation be used based on the physical disadvantages for dialysis of placement and retrieval and equilibration time.