Toxic Concentration: The concentration at which a substance produces a toxic effect.
Toxic Dose: The dose level at which a substance produces a toxic effect.
The concentration of a chemical or other pollutant representing a health threat in a given environment.
Source: Terms of the Environment
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LC 50/Lethal Concentration
Median level concentration, a standard measure of toxicity. It tells how much of a substance is needed to kill half of a group of experimental organisms in a given time. (See LD 50.)
Source: Terms of the Environment ...
Concentration. The amount of a substance in a given volume. In this case, a measurement of the fraction of the atmosphere composed of a certain gas.
Concentration: The amount of a particular substance that exists within a certain volume or weight of air, water, soil, or other medium.
Concentration The amount of material dissolved in a unit of solution, expressed in mg/L.
Contaminant Any foreign component in a substance, for example in water.
Concentration
The amount of a substance present in a certain amount of soil, water, air, food, blood, hair, urine, breath, or any other media.
Concentration: The quantity of one constituent dispersed in a defined amount of another.
Concentration process: The process of increasing the number of particles per unit volume of a solution, usually by evaporating the liquid.
Condensate: Water obtained by condensation of water vapor.
concentration
amount of a chemical or pollutant in a particular volume or weight of air, water, soil, or other medium.
condensation ...
Concentration - The relative amount of a substance mixed with another substance. Examples are 5 ppm of carbon monoxide in air and 1 mg/l of iron in water.
concentration
Any one of a group of three quantities characterizing the composition of a mixture and defined as one of mass, amount of substance (chemical amount) or number divided by volume, giving, respectively, mass, ...
concentration polarization. 1) The ratio of the salt concentration in the membrane boundary layer to the salt concentration in the bulk stream.
Concentration is measured using two units, because it is a measure of how much of one substance is contained in another. Typical units of concentration are described below.
C concentration-effect relationship
Definition (english only)
Link between the exposure of a given system to a substance over time and the magnitude of a specific, continuously graded change to that system ...
Bioconcentration: The accumulation of a chemical in tissues of a fish or other organism to levels greater than in the surrounding medium.
Biodegradable: Capable of decomposing under natural conditions.
Bioconcentration
The accumulation of a chemical in tissues of an organism (such as a fish) to levels greater than in the surrounding medium in which the organism lives.(1) ...
Isoconcentration: More than one sample point exhibiting the same isolate concentration.
Isopleth: The line or area represented by an isoconcentration.
Odour concentration - the concentration of an odour in terms of OU per cubic meter. A concentration of 1,000 OU/m3 means that the sample requires a dilution with clean air 1,000 times in order to become odour free.
ionic concentration The concentration of any ion in solution, usually expressed in moles per liter.
Lethal Concentration 50: Also referred to as LC50, a concentration of a pollutant or effluent at which 50 percent of the test organisms die; a common measure of acute toxicity.
Concentration - The amount of one substance dissolved or contained in a given amount of another substance or medium. For example, sea water has a higher concentration of salt than fresh water does.
Concentration Level (low or medium): Characterization of soil samples or sample fractions as low concentration or medium concentration is made on the basis of the laboratory's preliminary screen, ...
A concentration unit of chemical constituents in solution; the weight of solute per unit volume of solvent, usually water, one thousand micrograms per liter is equivalent to 1 milligram per litre, this measure is equivalent to parts per billion.
The concentration of hydrogen ions in a solution is very important for living things. This is because, since the hydrogen ions are positively charged they alter the charge environment of other molecules in solution.
Global concentrations of carbon dioxide, methane and nitrous oxide"three of the most notable greenhouse gases"have increased significantly over the past 250 years as direct result of human activities.
If the concentration reaches 5%, it will kill you. though it forms only 387 parts per million of the atmosphere, it acts like an effective planetary greenhouse. CO₂ is one of the greenhouse gases.
Having concentrations of nutrients optimal or nearly so for piant or animal growth. It is used to describe nutrient or soil solutions.
evapotranspiration ...
Exposure Concentration- The concentration of a chemical or other pollutant representing a health threat in a given environment.
Plume
A concentration of contaminants in air, soil, or water usually extending from a distinct source.
A unit of concentration for air contaminants. A mercury vapor level of 1.0 mg/m3 means that one milligram (one thousandth of a gram) of mercury vapor was detected in each cubic meter of sampled air.
Milligram per kilogram (mg/kg) ...
The maximum concentration of a chemical compound which can result when it is dissolved in water. If a substance is water soluble, it can very readily disperse through the environment.
Hardness: The concentration of calcium or magnesium in water; affects the availability of nutrients and toxic substances to stream organisms.
Headwaters: Small streams and creeks at the uppermost end of a river system.
Exposure: The concentration of the pollutant in the air multiplied by the population exposed to that concentration over a specified time period.
LC50: The concentration of a material in air that on the basis of laboratory tests (inhalation route of entry) is expected to kill 50% of a group of test animal when administered as a single exposure in a specific time period.
Diurnal Ozone Concentration - The ozone concentration in the troposphere is directly related to the pollutants that are in the air and the time of day. For example, during the early hours of the day many pollutants are released into the air.
Action level-Concentration of a substance in air, soil, water or other defined medium at which specified emergency counter-measures should be taken. (IUPAC) ...
Air Pollutant: Any substance in air that could, in high enough concentration, be harmful. Pollutants may include solids, liquids, gases or any combination thereof. Air pollutants are often grouped in categories for ease in classification.
Compared with C4 plants, C3 plants show a greater increase in photosynthesis with a doubling of CO2 concentration and less decrease in stomatal conductance, which results in an increase in leaf-level water-use efficiency. C4 plants Plants (e.g.
a measure of hydrogen ion concentration or acidity. The pH scale ranges from 0 (most acid) to 14 (most basic), with a pH of 7 being neutral.
salinity The relative concentration of dissolved salts in water. saturated zone The area below the water table where all open spaces are filled with water. Compare unsaturated zone.
pH A scale of acidity (1 - 7) or alkalinity (7 - 14) derived from the logarithm of the concentration of hydrogen ions (10 - 1 - 10 - 14). Phagocyte White blood-corpuscle capable of destroying harmful bacteria.
RfC- Reference Concentration
RFD- Reference Dose Values
RFI- Remedial Field Investigation
RFP- Reasonable Further Programs. Request for Proposal
RHRS- Revised Hazard Ranking System
RI- Reconnaissance Inspection
RI- Remedial Investigation ...
Plant growth can be limited by a number of factors, including soil fertility, water, temperature, and carbon dioxide concentration. Lack of carbon dioxide can induce photorespiration, which can destroy existing sugars.
#10 Protecting the world's climate by stabilizing atmospheric concentrations of greenhouse gases will require enormous reductions in current emissions.
Since carbon dioxide is directly involved in photosynthesis as a substrate it is not to suprising that photosynthesis shows a strong response to carbon dioxide concentration.
The reservoir species are important because their concentration tells us how many chlorine atoms are potentially available to destroy ozone in the perturbed chemical conditions of polar winters (see Part II: Chemical reactions leading to ozone loss ...
Salinity: refers here to the concentration of salt in the water
Salp: barrel-shaped pelagic tunicates belonging to the classes Thaliacea and Larvacea.
Indoor Air Quality (IAQ) - Indoor air that contains no known contaminants at harmful concentrations and with which a substantial majority of the people exposed to the air do not express dissatisfaction.
DISSOLVED OXYGEN CONTENT This is an important means of measuring the 'health' of a stretch of river or quantity of water by checking the concentration of oxygen. It is usually measured in mg/l (milligrams per litre).
Major loading of OCs and mercury between 1950 and the 1970 are still affecting the Great Lakes Basin today, home to 63 First Nations communities, although "concentrations of some chemicals decreased in the mid and late 1970s, ...
SALINITY: Generally, the concentration of mineral salts dissolved in water. Salinity may be measured by weight (total dissolved solids - TDS), electrical conductivity, or osmotic pressure.
Plume: In groundwater a plume is an underground pattern of contaminant concentrations created by the movement of groundwater beneath a contaminant source. Contaminants spread mostly laterally in the direction of groundwater movement.
Hardness The sum of the divalent cation concentrations expressed as meq/L or mg calcium carbonate per liter [mg CaCO3/L].
carbon dioxide (CO2) - a naturally occurring greenhouse gas in the atmosphere, concentrations of which have increased (from 280 parts per million in preindustrial times to over 350 parts per million today) as a result of humans' burning of coal, ...
Condenser
removes high concentrations of solvent vapours from gas streams by cooling, allowing both the liquid solvent fraction and the gas to be recycled or otherwise treated ...
ACGG = atmospheric concentration (of) GhG
ACGG unit = standard unit for measuring the local atmospheric concentration of GhG ...
Increasing concentrations of these gases, and the release in recent years of more powerful synthetic ones, are behind concerns about climate change.
Maximum Contaminant Level (MCL): enforceable EPA standard for the maximum permissible concentration of a contaminant in public water supplies.
Assay: An in vitro test system used to estimate the concentration or potency of a substance by measuring its biological response.
Asthma: A chronic inflammatory disorder of the airways.
 See also: Water, Environment, Air, Waste, Environmental
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