Introduction

In recent years there has been renewed interest in environmental studies that combine knowledge gained from several specialized sciences. Particularly noteworthy examples of such studies are those that combine analyses of particle size distributions with chemical analyses of the composition of sediments. Geochemical studies lead to understanding cycles, fluxes, budgets, sources, and sinks of chemical elements in nature. Particle size distributions are an intimate reflection of, or a controlling factor in, most of these geochemical processes.

It has been well known that fine-grained sediments tend to have relatively high metal contents, due in part to the high specific surface area of the smaller particles. This enrichment is mainly due to surface adsorption and ionic attraction (Balistrieri et al., 1981; Li, 1981; McCave, 1984; Horowitz & Elrick, 1987). Trace elements can also be concentrated in iron and manganese oxyhydroxides, which tend to be associated with fine-grained sediments (Tessier et al., 1985). Finally, coatings of organic matter are prevalent in fine-grained sediments, and these coatings bind a variety of trace elements (Wangersky, 1986).

Geochemical characteristics of a sediment can be used to infer the provenance and transport history of the sediment. This knowledge has been used to determine mineral source areas (Baldi & Bargagli, 1982; Tessier et al., 1982), and to determine the source of pollution (Oliver, 1973; Forstner & Salomons, 1980). Such knowledge is often essential in dealing with problems of disposal of drilling, mining, or dredging wastes.