A Retrospective Assessment of Artificial, Formulated and Synthetic Sediment
Keywords:synthetic sediment, sediment data quality, reference sediment, control, formulation
Understanding aquatic sediment's inherent complexity requires multiple assessment tools and lines of evidence to explain its composition, character and function. Data quality of sediment assessments can suffer from a lack of suitable "control" or "reference" sediment material; natural sediment is too dynamic and heterogeneous to serve this role. One promising solution is to create surrogate sediment substrates (3S) composed of synthetic materials. The development of 3S has not progressed beyond a few, decades-old approaches. Taking inventory of current conditions often can clarify context and goals, and inspire new ideas to overcome the current stagnation. To this end, the author reviewed 114 articles that report using 3S in studies of sediment mechanics, sediment ecology (habitat), and toxicity and bio-assimilation of sediment-associated chemicals. The review disclosed an apparent systematic error in previous synthetic sediment formulations: the presumed silt components were actually clay minerals, perhaps leading to misinterpretation of results under invalid composition assumptions. Organic matter composition and other higher-level sediment characteristics continue to be major challenges to progress. The review identified a few solitary efforts at incorporating high-level sediment properties in 3S formulations, such as inherent nutritional value of synthetic sediment, acid-volatile sulfide content, oxidation-reduction potential, reproducible conditioning and equilibration, and microbiological populations. It also revealed an underlying (subconscious?) presumption: that a single (currently elusive) universal formulation can meet all sediment study objectives. This unspoken presumption has imposed unnecessarily daunting expectations. An alternative proposal is to develop multiple 3S materials, each formulated with assessment- or DQO-specific characteristics pertinent to its intended use. The information consolidated in this review can be a platform for future progress in the field.
Permanent URL: http://hdl.handle.net/2047/d20003408