Sediment pore water collection methods for trace metal analysis: A review

Collection and analysis of pore water has become an important aspect of many environmental programs. Pore water analyses are used for toxicity identification, sediment quality assessment and diagenetic studies. This paper reviews the four commonly used methods for collection of pore water and potential artifacts from their use, particularly in the preparation of samples for trace metal analysis. Two of the methods, centrifugation and squeezing, are ex situ, requiring the removal of sediment from the natural environment. The other two, dialysis and suction filtration, are used in situ. Each method has its advantages and disadvantages, and usage must be determined by the individual researcher. The handling of most samples should be conducted in an inert atmosphere until pore water samples are acidified because oxidation has been shown to significantly alter sample speciation. Significant errors have also been found to result from temperature alteration. Sample contamination by fine particles is important in all methods as differentiation of particulate and soluble components is based on membrane pore size.