Assessment and Transport of Sediment-Bound Estuarine Contaminants

• Published in: Exposure and health 2015-03, Vol.7 (1), p.5-14
• Main Authors: Work, P. A., Haas, K. A., Warren, D. A., Elci, Ş.
• Format: Article
• Language: English
• Subjects: Anthropogenic factors; Aquatic Pollution; Bioturbation; Boundary conditions; Brackish; Case studies; Chemical contaminants; Contaminants; Decay rate; Diffusion coefficient; Diffusion rate; Earth and Environmental Science; Environment; Environmental Health; Environmental impact; Estuaries; Estuarine environments; Fluid flow; Fluid mechanics; Heavy metals; Load distribution; Loading rate; Metals; Ocean currents; Organic chemicals; Pollution; Pollution transport; Risk assessment; Sea level rise; Sediment transport; Sediments; Surface water; Time dependence; Transport processes; Waste Water Technology; Water and Health; Water flow; Water Management; Water Pollution Control; Water Quality/Water Pollution; Wetlands
• ISSN: 1876-1658; 2451-9766; 1876-1666; 2451-9685
• DOI: 10.1007/s12403-013-0101-7

Estuaries and coastal bays frequently receive anthropogenically sourced contaminants. Many of these contaminants (e.g. most metals) have low solubility and tend to sorb to sediment particles, so that sediment transport driven by fluid mechanics becomes an important part of the contaminant transport problem. The chosen strategy for mitigation of the contaminant(s) will depend on the potential for migration away from the affected region, or the build-up of concentrations within the receiving area if loading rate exceeds decay or transport rates, and the potential impact on environmental and human health both within and outside the receiving area. Two case studies are considered here in which data describing instantaneous contaminant concentrations in estuarine environments were acquired via field sampling. Both sites feature estuaries dominated by tidal forcing, with smaller, adjacent upland regions also impacted. Metals, particularly copper and lead, are the primary focus in each case. Contaminant transport processes, including diffusion, advection, and bioturbation, are treated together to develop analytical and numerical solutions for time-dependent contaminant concentrations using a spatially varying, time-dependent, effective diffusion coefficient that is influenced by local surface water flow speeds. Different initial, boundary, and loading conditions are considered to illustrate the relative importance of the various transport processes. Implications of future contaminant loading and sea level rise scenarios are demonstrated and discussed.