Toxics

HydroQual’s expertise in the fate, transport and bioaccumulation of toxic substances is the foundation of several of our service areas (e.g., contaminated sediment modeling, ecological risk assessment, natural resource damage assessments, water and sediment criteria development, total maximum daily loads, dredged material management, and mine tailings management). Much of the development of modern contaminant fate and transport modeling technology and water column-bed sediment interactions as well as the development of modern sediment quality criteria based on bioavailability may be credited to Dominic DiToro (1990, 1991, 1992), a HydroQual co-founder.

Modeling of contaminant fate and transport requires that particulate and dissolved organic carbon and sulfides be tracked through the water column and sediment of a given water body since these are the phases to which hydrophobic chemicals and metals sorb. This is readily accomplished by linking HydroQual’s eutrophication and sediment transport experience and expertise with HydroQual’s toxic substances acumen. HydroQual’s in-depth capabilities for toxic substance evaluations are further enhanced, particularly for metals, by our understanding of thermodynamic chemistry and speciation. Correct calculation of the levels of toxic substances in water and sediments facilitates HydroQual’s ability to calculate subsequent food chain transfers.

HydroQual has worked on toxic substance evaluations involving a long list of contaminants including, metals, PCBs, dioxin/furans, PAHs, and organochlorine, carbamate, and pyrethroid pesticides in both marine and fresh water settings. HydroQual draws upon a wide-range of simple and complex tools to accomplish toxic substance evaluations (e.g., MonteCarlo simulation techniques, GISTOX, WASTOX, RCATOX, BLM, etc.).

DiToro et al., 1990. Toxicity of cadmium in sediments: the role of acid volatile sulfide. Env. Tox. Chem. 9:1487-1502.

DiToro et al., 1991. Technical basis for establishing sediment quality criteria for nonionic organic chemicals using equilibrium partitioning. Annual Review. Env. Tox. Chem. 10:1541-1583.

DiToro et al., 1992. Acid volatile sulfide predicts the acute toxicity of cadmium and nickel in sediments. EST. 26:96-101.