Acute Toxicity - Toxicity having a sudden onset, lasting a short time and severe enough to induce a response rapidly. The duration of an acute aquatic toxicity test ii generally on the order of days and mortality is the response measured.
Adsorption – The Adhesion of one substance on the surface of another.
Advection - The horizontal movement of a mass of water that causes changes in temperature or in other physical properties of the water.
Area Use – The extent to which an area Is Used (E.G., For Feeding, Rearing) By Organisms Such As Fish.
Assessment Endpoint - The undesired effect whose probability of occurrence is estimated in a risk assessment. The explicit expression of the environmental value that is to be protected. examples include extinction of an endangered species, eutrophication of a lake, or loss of a fishery.
Benthic - Referring to organisms living in or on the sediments of aquatic habitats.
Benthos - The sum total of organisms (including plants and animals) living in, or on, the sediments of aquatic habitats.
Biaccessibility – The fraction of a chemical present in the environment that is not immediately bioavailable but which may be available for uptake by organisms over the long term.
Bioassay - The use of an organism or part of an organism as a method for measuring or assessing the presence or biological effects of one or more substances under defined conditions. a bioassay test is used to measure a degree of response (e.g., growth, or death) produced by exposure to a physical, chemical or biological variable (a toxicity test) or uptake of a chemical into an organism (a bioaccumulation test).
Bioavailability – Refers to the fraction of the total chemical in the surrounding environment which can be taken up by organisms. the environment may include water, sediment, suspended particles, and food items.
Biomagnification – Uptake of a contaminant through a food chain resulting in increasing concentrations through three or more trophic levels.
Bioturbation - The movement and relocation of bottom sediments by the activities of bottom-dwelling organisms.
Chronic Toxicity – A biological response of relatively slow progress and long continuance, usually associated with lower concentrations of chemicals than would cause an acute toxicity response.
Coincidental Sampling – Different field-collected samples from the same area/station are used for different analyses.
Conceptual Site Model – A three-dimensional representation of a site and its environment that represents what is known or suspected about contaminant sources as well as the physical, chemical and biological processes that affect contaminant transport to potential environmental receptors.
Contamination – A substance present where it should not be or at concentrations higher than background.
Diffusion - The random movement and scattering of water-soluble contaminants in the interstitial waters of sediments and into the overlying water column.
Distal – Situated away from the point of origin.
Ecological Risk Assessment - The process that evaluates the likelihood that adverse ecological effects may occur or are occurring as a result of exposure to one or more stressors. this definition recognizes that a risk does not exist unless: (1) the stressor has an inherent ability to cause adverse effects, and (2) it is coincident with or in contact with the ecological component long enough and at sufficient intensity to elicit the identified adverse effect(s).
Effect – A change to a valued ecosystem component due to human activities. an effect is not necessarily a negative impact; and effect may be neutral or even positive.
Empirical – Derived from or depending on experience or observation/experimentation rather than theory or logic.
Human Health Risk Assessment - the process that evaluates the likelihood that adverse human health effects may occur or are occurring as a result of exposure to one or more stressors. this definition recognizes that a risk does not exist unless: (1) the stressor has an inherent ability to cause adverse effects, and (2) it is coincident with or in contact with the one or more humans long enough and at sufficient intensity to elicit the identified adverse effect(s).
Hypothesis – An assumption made in order to evaluate a logical possibility.
Impact – An effect on a population of organisms other than humans that adversely affects the utility or viability of that population. in the case of humans or endangered species, an impact would not occur at the population but rather at the individual level because individuals are protected, not populations.
Infauna – invertebrate organisms living within the bottom sediment of fresh, estuarine or marine waters.
Iinterfacial – Having a common boundary; point of connection.
Invertebrate - Animal lacking a dorsal column of vertebrae or a notochord.
Lentic – Non-flowing (static) water bodies such as lakes, ponds and marshes.
Line of Evidence – A component of weight of evidence determinations (e.g., toxicity, benthos alteration, biomagnification, chemical contamination).
Lotic – Flowing water bodies such as creeks, streams and rivers.
Mean – The arithmetic average of a collection of numbers, computed by adding them up and dividing by their number.
Measurement Endpoint - An expression of an observed or measured response to a hazard; it is a measurable environmental characteristic that is related to the valued characteristic chosen as the assessment endpoint.
Oxidation – Addition of oxygen, removal of hydrogen, or removal of electrons from an element or compound.
Pollution – Contamination resulting in adverse biological effects.
Productivity – The ability to produce life (e.g., number of offspring produced by fish).
Receptor - The entity (e.g., organism, population, community, ecosystem) that might be adversely affected by contact with or exposure to a substance of concern.
Redd – Fish such as trout and salmon build nests called redds for their eggs.
Reference - A designated site, or set of conditions, used for comparison when evaluating sediment for contamination or pollution.
Remediation – An activity undertaken to correct an unacceptable existing condition (e.g., treating or reducing effluent inputs).
Sediment - Material, such as sand or mud, suspended in or settling to the bottom of a liquid. sediment input to a body of water comes from natural sources, such as erosion of soils and weathering of rock, or as the result of anthropogenic activities, such as forest or agricultural practices, or construction activities.
Sediment Quality Guideline – A numerical value for one or more chemicals related to a level of probability (but not of certainty) that adverse environmental effects may or may not occur above or below the guideline value.
Sensitivity Analysis – Analysis undertaken to determine what data or information are primarily responsible for an assessment.
Species Sensitivity Distribution – A graphical representation of the different sensitivities of different species to the same stressor. used to determine the concentration or level of a stressor protective of most species in the environment.
Standard Deviation – A measure of the range of variation from an average or mean of a group of measurements. 95% of all measurements fall within two standard deviations of the mean.
Stochastic Uncertainty – The inherent randomness of a system being assessed; can be described and estimated but cannot be reduced.
Surficial – On the surface.
Synoptic Sampling – Sub-samples for analyses are taken from the same, generally composite, sample.
Toxic – Poisonous, carcinogenic, or otherwise directly harmful to a living organism.
Toxicity Identification Evaluation – a methodology for determining the causative agent(s) for toxicity identified in toxicity tests. specific contaminants are removed and the sample retested until toxicity has been removed, then the presumed causative agent(s) are added back in and the sample retested to confirm that they are indeed the causative agent(s).
Trophic level – Functional classification of organisms in a community according to feeding relationships – e.g., the first trophic level includes green plants, the second level includes herbivores (plant eaters), etc. Valued Ecosystem Component – An environmental attribute or component having scientific, social, cultural, economic, or aesthetic value.
Water Quality Guideline – A numerical value for one or more chemicals related to a level of probability (but not of certainty) that adverse environmental effects may or may not occur above or below the guideline value.
Weight of Evidence – A determination related to possible ecological impacts based on multiple lines of evidence.