Glossary: Environmental chemistry

activated charcoal. activated carbon; active carbon.

A porous form of carbon that acts as a powerful adsorbent, used to decolorize liquids, recover solvents, and remove toxins from water and air.

carbonate hardness. carbonate water hardness. Compare with water hardness.

Water hardness due to the presence of calcium and magnesium carbonates and bicarbonates. The "noncarbonate hardness" is due mostly to calcium and magnesium sulfates, chlorides, and nitrates.

cyanide process.

A method for separating a metal from an ore. Crushed ore is treated with cyanide ion to produce a soluble metal cyanide complex. The complex is washed out of the ore and reduced to metallic form using an active metal (usually zinc).

dissolved oxygen. DO.

The amount of oxygen dissolved in a solvent (usually water). Dissolved oxygen levels are used as a general indicator of water quality.

domoic acid.

Domoic acid is a toxic amino acid produced by certain species of algae. Domoic acid binds to a receptor that helps nerve cells control the flow of ions across their cell membranes. The receptor no longer works correctly, and the uncontrolled flux of ions damages and eventually kills the nerve cell.

environmental chemistry. chemical ecology.

The study of natural and man-made substances in the environment, including the detection, monitoring, transport, and chemical transformation of chemical substances in air, water, and soil.

excitotoxin.

An excitotoxin is a toxic molecule that stimulates nerve cells so much that they are damaged or killed. Domoic acid and glutamate are examples of excitotoxins.

free radical.

A free radical is a molecule with an odd number of electrons. Free radicals do not have a completed octet and often undergo vigorous redox reactions. Free radicals produced within cells can react with membranes, enzymes, and genetic material, damaging or even killing the cell. Free radicals have been implicated in a number of degenerative conditions, from natural aging to Alzheimer's disease.

glutamate receptors.

Glutamate receptors are protein molecules that helps gate the flow of ions across a nerve cell's membrane. They play a role in the formation of new connections between nerve cells (and so, in learning and memory). The receptors are normally activated by aspartate and glutamate. In amnesic shellfish poisoning, domoic acid acts as an excitotoxin that very strongly activates some of these receptors, preventing their proper functioning.

molecular sieve.

A material that contains many small cavities interconnected with pores of precisely uniform size. Zeolites are an example. Molecular sieves adsorb molecules that are small enough to pass through their pore systems- especially water. They are often used as drying agents, and to separate large molecules from smaller ones in preparatory work and in exclusion chromatography.

neurotransmitter.

Neurotransmitters are molecules that are used to carry signals from one neuron to another. One neuron releases the neurotransmitter near another neuron's receptors. The neurotransmitter diffuses across the gap between the neurons and locks into a receptor site on the surface of the downstream neuron. This induces a change in the downstream neuron.

permanent hardness. permanent water hardness. Compare with temporary hardness and water hardness.

Water hardness that remains after boiling the water, mainly due to dissolved calcium sulfate. Chlorides also contribute to permanent hardness.

temporary hardness. temporary water hardness. Compare with permanent hardness and water hardness.

The component of total water hardness that can be removed by boiling the water. Ca(HCO₃)₂ and Mg(HCO₃₎2_ are responsible for temporary hardness.

teratogen.

A substance that can cause deformities in embryos. Dioxin is a teratogen.

water hardness. hard water. Compare with water softener.

Hard water is water contaminated with compounds of calcium and magnesium. Dissolved iron, manganese, and strontium compounds can also contribute to the "total hardness" of the water, which is usually expressed as ppm CaCO₃. Water with a hardness over 80 ppm CaCO₃ is often treated with water softeners, since hard water produces scale in hot water pipes and boilers and lowers the effectiveness of detergents.

water softener. soft water; water softening. Compare with water hardness.

A material that lowers water hardness when dissolved in water. For example, sodium carbonate ("washing soda") softens water by precipitating Ca²⁺ ions as CaCO₃. Zeolites soften water by exchanging Ca²⁺ ions with Na⁺ ions.

water softening. Compare with water softener and water hardness.

Removal of Ca²⁺ and Mg²⁺ from water to prevent undesirable precipitation reactions from occurring in plumbing, pools, washwater, and boilers.

Copyright © 1997-2010 by Fred Senese
Comments & questions to fsenese@frostburg.edu
Last Revised 02/23/18.URL: http://antoine.frostburg.edu/chem/senese/101/environmental/glossary.shtml