CCD Help Pages | Env. Fate/Transport categories

Publish date: 2024-05-05

Bioaccumulation factor

Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism.[1] Bioaccumulation occurs when an organism absorbs a substance at a rate faster than that at which the substance is lost or eliminated by catabolism and excretion - WikipediaEXIT.

A more detailed EPA report.

Bioconcentration factor

Bioconcentration is a measure of the amount of pesticide residue in an organism’s tissue relative to the concentration in the organism’s environment. Bioconcentration factors (BCFs) are calculated by considering pesticide tissue concentrations with respect to environmental pesticide concentrations. EPA document.

Soil absorption coefficient (Koc)

Processes which influence the behavior of contaminants in the subsurface must be considered both in evaluating the potential for movement as well as in designing remediation activities at hazardous waste sites. Such factors not only tend to regulate the mobility of contaminants, but also their form and stability. Sorption is often the paramount process controlling the behavior of contaminants in the subsurface.

EPA report.

Biodegradation half-life

The rate of transformation of pesticides in the environment is commonly described using first-order kinetics, often referred to as single first-order (SFO). The first-order representation is convenient because the rate is summarized with a single parameter (the rate constant, k), and the rate of transformation is independent of the initial concentration. The half-life, t1/2 =ln(2)/k, indicates the time required to reduce the concentration by 50% from any concentration point in time. It is an intuitive way to express the rate of decline of a first-order degradation.

EPA guidance.

Atmospheric hydroxylation rate

The atmospheric hydroxylation rate (LogOH) constant for the atmospheric, gas-phase reaction between photochemically produced hydroxyl radicals and organic chemicals.

EPA publicationEXIT.

Fish biotransformation half-life (Km).

Bioaccumulation in fish is a function of competing rates of chemical uptake and elimination. For hydrophobic organic chemicals bioconcentration, bioaccumulation and biomagnification potential are high and the biotransformation rate constant is a key parameter. DOI: 10.1016/j.scitotenv.2013.10.068EXIT

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