Ph. Santschi et al., HETEROGENEOUS PROCESSES AFFECTING TRACE CONTAMINANT DISTRIBUTION IN ESTUARIES - THE ROLE OF NATURAL ORGANIC-MATTER, Marine chemistry, 58(1-2), 1997, pp. 99-125
Our objective in writing this paper is to frame the issues pertaining
to the role of natural organic matter in affecting the speciation and
transport (fate) of trace contaminants, which include hydrophilic trac
e metals and hydrophobic trace organics, within estuaries. In particul
ar, we focus on one aspect of the problem: the partitioning of trace c
ontaminants between organic and inorganic particles, colloids and solu
tion. This paper is developed along three main lines. First, we review
the literature with respect to trace metal sorption by metal oxides i
n the presence of organic ligands. Second, we examine the role of coll
oidal organic matter in regulating the estuarine behavior of trace con
taminants. The focus of this portion of the paper is on the trapping o
f trace metals within colloidal and particulate organic matter and a r
e-examination of the 'particle concentration effect'. Third, we propos
e a new conceptual model (the 'percolator' model) which links several
processes (sorption, diffusion, coagulation) and which serves as a fra
mework for evaluating the trapping of trace metals and organic matter
within estuarine sediments. One conclusion derived from simulations of
the diffusive flux of DOC from sediments is that the magnitude of sed
iment/water interfacial shear stress does not affect DOC flux until th
e shear stress is sufficient for the onset of bed erosion. The consequ
ence is that interactions between DOC and sediment materials become th
e controlling factors in regulating the diffusive flux of DOC. (C) 199
7 Elsevier Science B.V.