Glossary of Terms

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Aldicarb - Aldicarb is a carbamate insecticide with structural formula: 2-methyl-2-(methylthio)propionaldehyde O-methylcarbamoyloxime. Aldicarb is the active substance in Temik pesticide, which is effective against thrips, aphids, spider mites, lygus, fleahoppers, and leafminers but is primarily used as a nematicide. Aldicarb is moderately toxic to fish. The half-life of aldicarb in water is from one day to a few months. In pond water, aldicarb is broken down rapidly and has a half-life of five to 10 days. It is degraded by bacteria, sunlight, and reactions with water. Because of its rapid degradation rate, levels in surface water may be lower than those in groundwater.

Algae - Algae range from single-cell organisms to multicellular organisms, some with fairly complex differentiated form and (if marine) called seaweeds. All lack leaves, roots, flowers, seeds and other organ structures that characterize higher plants (vascular plants). They are distinguished from other protozoa in that they are photoautotrophic, although this in not a hard and fast distinction as some groups contain members that are mixotrophic, deriving energy from both photosynthesis and uptake of organic carbon.

Alkalinity - Alkalinity of water is its acid-neutralizing capacity. Because the alkalinity of many surface waters is primarily a function of carbonate, bicarbonate and hydroxide content, it is taken as an indication of the concentration of these constituents. The measured values also may include contributions from borates, phosphates, silicates or other bases if these are present. Alkalinity in excess of alkaline earth metal concentrations is significant in determining the suitability of water for irrigation.

Aluminum (Al) - Aluminum is the most abundant of all metals and the third most abundant element in the earth's crust. Aluminum is too reactive chemically to occur in nature as a free metal. Instead, it is found combined in over 270 different minerals. The chief source of aluminum is bauxite ore. It is one of the few abundant elements that appear to have no beneficial function to living cells.

Ammonia-Nitrogen (NH3-N) - Ammonia, naturally occurring in surface and wastewaters, is produced by the breakdown of compounds containing organic nitrogen. Ammonia is toxic to fish at relatively low concentrations in pH-neutral or alkaline water. Plants are more tolerant of ammonia than animals and invertebrates are more tolerant than fish.

Arsenic (Ar) - Arsenic is a semi-metal element in the periodic table. It is odorless and tasteless. It enters drinking water supplies from natural deposits in the earth or from agricultural and industrial practices. Higher levels of arsenic tend to be found more in ground water sources than in surface water sources.

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Barium (Ba) - Barium is a lustrous, machinable metal which exists in nature only in ores containing mixtures of elements. It is used in making a wide variety of electronic components, in metal alloys, bleaches, dyes, fireworks, ceramics and glass. In particular, it is used in well drilling operations where it is directly released into the ground. In water, the more toxic soluble barium salts are likely to be converted to insoluble salts which precipitate. Barium does not bind to most soils and may migrate to ground water. It has a low tendency to accumulate in aquatic life.

Benzene - Benzene is a clear, colorless aromatic liquid. It is highly flammable. The greatest use of benzene is as a building block for making plastics, rubber, resins and synthetic fabrics like nylon and polyester. Other uses include: as a solvent in printing, paints, dry cleaning, etc. If benzene is released into soil, it will either evaporate very quickly or leach to groundwater. It can be broken down by some soil microbes. It may also be degraded in some ground waters. If benzene is released into surface water, most of it should evaporate within a few hours. Though it does not degrade by reacting with water, it may be degraded by microbes. It is not likely to accumulate in aquatic organisms.

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Cadmium (Cd) - Cadmium is a metal found in natural deposits as ores containing other elements. The greatest use of cadmium is primarily for metal plating and coating operations, including transportation equipment, machinery and baking enamels, photography, television phosphors. It is also used in nickel-cadmium and solar batteries and in pigments. Some cadmium compounds are able to leach through soils to ground water. When cadmium compounds do bind to the sediments of rivers, they can be more easily bioaccumulated or re-dissolved when sediments are disturbed, such as during flooding. Its tendency to accumulate in aquatic life is great in some species, low in others.

Calcium (Ca) - Calcium is a soft grey alkaline earth metal, and is the fifth most abundant element in the Earth's crust. It is essential for living organisms, particularly in cell physiology, and is the most common metal in many animals. The most common forms of calcium are calcium carbonate (calcite) and calcium magnesium carbonate (dolomite).

Carbamates - The carbamate pesticides are mainly used in agriculture, as insecticides, fungicides, herbicides, nematocides, or sprout inhibitors. In addition, they are used as biocides for industrial or other applications and in household products. These chemicals are part of the large group of synthetic pesticides that have been developed, produced, and used on a large scale in the last 40 years. More than 50 carbamates are known.

Carbon Tetrachloride - Carbon tetrachloride is a clear heavy organic liquid with a sweet aromatic odor similar to chloroform. Most of it is used to make chlorofluorocarbon propellants and refrigerants, though this has been declining steadily. Other uses have included: use as dry cleaning agent and fire extinguishers, in making nylon, as a solvent for rubber cement, soaps, insecticides, etc. Carbon tetrachloride evaporates quickly from surface waters and soil. It does not bind to soil and may leach into ground water. It has a low potential to accumulate in aquatic life.

Carbaryl - Carbaryl (1-naphthyl methylcarbamate) is a chemical in the carbamate family used chiefly as an insecticide. It is a colorless white crystalline solid. Carbaryl does not dissolve well in water and sticks to soil. Carbaryl ranges from slightly to highly toxic to several species of fish. Carbaryl is very highly toxic to aquatic invertebrates such as shrimp and stoneflies. Carbaryl can also damage frog tadpoles during their development.

Carbofuran - Carbofuran is a white crystalline solid with a slightly phenolic odor. This broad spectrum insecticide is sprayed directly onto soil and plants just after emergence to control beetles, nematodes and rootworm. The greatest use of carbofuran is on alfalfa and rice, with turf and grapes making up most of the remainder. Earlier uses were primarily on corn crops. If released to soil or water, carbofuran will be broken down by reactive chemicals and microbes, particularly in alkaline conditions. Carbofuran may leach significantly in many soils. Leaching may not occur, in very high organic content soils. It is not expected to accumulate in aquatic organisms.

Chloride (Cl-) - Chlorides are salts resulting from the combination of the gas chlorine with a metal. Some common chlorides include sodium chloride (NaCl) and magnesium chloride (MgCl2). Chlorides are not usually harmful to people. The salty taste produced by chloride concentrations is variable dependent on the chemical composition of the water.

Chlorobenzene - Chlorobenzene is a colorless organic liquid with a faint, almond-like odor. The greatest use of chlorobenzene is in the manufacture of other organic chemicals, dyestuffs and insecticides. It is also a solvent for adhesives, drugs, rubber, paints and dry-cleaning, and as a fiber-swelling agent in textile processing. Releases into water and onto land will either evaporate or be slowly degraded by microbes in the soil or water. Since it does not bind to soils, it can be expected to leach into the groundwater. Little accumulation is expected in fish and food products.

Chlorodibromomethane - Chlorodibromomethane is a colorless to yellow, heavy, nonburnable liquid with a sweetish odor. This chemical is a possible contaminant of drinking water that has been chlorinated to kill bacteria and viruses. Chlorodibromomethane may form when chlorine reacts with other naturally occurring substances in water, such as decomposing plant material. In water, chlorodibromomethane is slowly broken down at the water surface where oxygen is available, but breaks down much faster in deep water and in water that is underground where there is a lot less oxygen. Chlorodibromomethane is mobile in soils and may seep into groundwater. Chlorodibromomethane does not appear to concentrate in fish.

Chloroform - Chloroform is a colorless liquid with a pleasant, nonirritating odor and a slightly sweet taste. It doesn't stick to soil very well and can travel through soil to groundwater. Chloroform dissolves easily in water and some of it may break down to other chemicals. Chloroform lasts a long time in groundwater. Chloroform doesn't appear to build up in great amounts in plants and animals.

Chlorophyll a (Chl a) - Chlorophyll a is a photosynthetic pigment which is found in all green plants. Chlorophyll a is used as an algal biomass indicator. Biomass is a quantitative estimate of the total mass of living organisms within a given area or volume. An excess of algae can lead to taste and odor issues in drinking water.

Chromium (Cr) - Chromium is a metal found in natural deposits as ores containing other elements. The greatest use of chromium is in metal alloys such as stainless steel; protective coatings on metal; magnetic tapes; and pigments for paints, cement, paper, rubber, composition floor covering and other materials. Its soluble forms are used in wood preservatives. When released to land, chromium compounds bind to soil and are not likely to migrate to ground water. They are very persistent in water as sediments. There is a high potential for accumulation of chromium in aquatic life.

Cobalt (Co) - Cobalt is a hard, lustrous, silver-grey metal. It is found in various ores, and is used in the preparation of magnetic, wear-resistant, and high-strength alloys. Its compounds are used in the production of inks, paints, and varnishes.

Conductivity - The conductivity of water provides information on its chemical composition. Conductivity is a measurement of the ability of an aqueous solution to carry an electrical current. There are several factors that determine the degree to which water will carry an electrical current. These include: 1) the concentration or number of ions; 2) mobility of the ion; 3) oxidation state and 4) temperature of the water.

Copper (Cu) - Copper is a metal found in natural deposits as ores containing other elements. It is widely used in household plumbing materials. Copper may occur in drinking water either by contamination of the source water used by the water system, or by corrosion of copper plumbing. Corrosion of plumbing is by far the greatest cause for concern. Copper is rarely found in source water, but copper mining and smelting operations as well as municipal incineration may be sources of contamination.

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1,3-Dichloropropene - 1,3-Dichloropropene is a colorless liquid with a sweet smell. It dissolves in water and evaporates easily. It is used mainly in farming as a pesticide. 1,3-Dichloropropene in soil is likely to be broken down by microorganisms. It dissolves in water but breaks down slowly. Some 1,3-dichloropropene in water and soil evaporates rapidly into the air where it is broken down by sunlight. Some 1,3-dichloropropene in soil may travel deeper into the ground and reach groundwater.

Dissolved oxygen (DO) - The amount of oxygen freely available in water. Traditionally, the level of dissolved oxygen has been accepted as the single most important indicator of a water body's ability to support desirable aquatic life. DO is supplied to a waterbody through the diffusion of atmospheric oxygen into the water and the photosynthetic production of oxygen by algae and aquatic weeds. Respiratory processes, oxidation of inorganic wastes, and the decomposition of organic matter decrease oxygen concentrations in water.

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E. Coli - E. coli is a member of the fecal coliform group of bacteria. This organism in water indicates fecal contamination by warm blooded animals and may be an indicator of the presence of other pathogens.

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Fecal coliform - Fecal coliform is a group of bacteria that can originate both in feces and without the presence of feces. The presence of fecal coliform bacteria in aquatic environments may indicate that the water has been contaminated with the fecal material of warm blooded animals. However, their presence may also be the result of plants, cold-blooded organisms, and pulp or paper mill effluent.

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Hardness - Hardness is a measurement of the mineral content of water. This content usually consists of levels of metal ions, mainly calcium and magnesium in the form of carbonates, but may include several other metals as well as bicarbonates and sulfates.

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Lead (Pb) - Lead, a metal found in natural deposits, is commonly used in household plumbing materials and water service lines. The greatest exposure to lead is swallowing or breathing in lead paint chips and dust. Lead is rarely found in source water, but enters tap water through corrosion of plumbing materials.

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Macrophyte - Macroscopic forms of aquatic vegetation that encompasses macroalgae, the few species of mosses and ferns adapted to the aquatic habitat, as well as true angiosperms.

Magnesium (Mg) - Magnesium is the ninth most abundant element in the universe by mass. Magnesium occurs commonly in the minerals magnesite and dolomite. Magnesium ion is essential to all living cells.

Manganese (Mn) - Manganese is a grey-white metal resembling iron. It is found as the free element in nature (often in combination with iron), and in many minerals. The free element is a metal with important industrial metal alloy uses. Manganese ions are variously colored and are used industrially as pigments and as oxidation chemicals.

Metals - The effects of metals in water and wastewater range from beneficial through troublesome to dangerously toxic. Some metals are essential to plant and animal growth while others may adversely affect water consumers, wastewater treatment systems and receiving waters. The benefits versus toxicity of some metals depend on their concentrations in water. Some common metals include: aluminum, arsenic, barium, cadmium, chromium, cobalt, copper, lead, manganese, mercury, nickel, selenium, silver, vanadium, and zinc.

Methomyl - Methomyl is a highly toxic compound used as a broad spectrum insecticide. It is also used as an acaricide to control ticks and spiders. Methomyl is moderately to highly toxic to fish and highly toxic to aquatic invertebrates. Aqueous solutions of methomyl have been reported to decompose more rapidly on aeration, in sunlight, or in alkaline media.

Methyl Tertiary Butyl Ether (MTBE) - MTBE is achemical compound that is manufactured by the chemical reaction of methanol and isobutylene. MTBE is produced in very large quantities (over 200,000 barrels per day in the U.S. in 1999) and is almost exclusively used as a fuel additive in motor gasoline. It is one of a group of chemicals commonly known as "oxygenates" because they raise the oxygen content of gasoline. Low levels of MTBE can make drinking water supplies undrinkable due to its offensive taste and odor.

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Nickel (Ni) - Nickel is a silvery white metal that takes on a high polish. It occurs most usually in combination with sulfur and iron in pentlandite, with sulfur in millerite, with arsenic in the mineral nickeline, and with arsenic and sulfur in nickel glance.

Nitrate+Nitrite Nitrogen (NO3+NO2) - Nitrates and nitrites are nitrogen-oxygen chemical units which combines with various organic and inorganic compounds. In waters and wastewaters the forms of nitrogen of the greatest interest are nitrate, nitrite, ammonia, and organic nitrogen. Since they are very soluble and do not bind to soils, nitrates have a high potential to migrate to ground water. Because they do not evaporate, nitrates/nitrites are likely to remain in water until consumed by plants or other organisms.

Nutrient - Any substance used by living things to promote growth. The term is generally applied to nitrogen and phosphorus in water and wastewater, but is also applied to other essential and trace elements.

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Orthophosphate phosphorus (PO4) - Phosphorus occurs in natural waters and in wastewaters almost solely as phosphates. They occur in solution, in particles or detritus, or in the bodies of aquatic organisms. The growth of macrophytes and phytoplankton is stimulated principally by nutrients such as phosphorus and nitrogen.

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pH - pH is a measure of the hydrogen ions in a solution. Measurement of pH is one of the most important and frequently used tests in water chemistry.

Potassium (K) - Potassium compounds are used in glass, fertilizers, baking powder, soft drinks, explosives, electroplating, and pigments. Potassium is an essential element in both plant and animal nutrition.

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Salinity - Dissolved salt content of a body of water. Salinity is an ecological factor of considerable importance, influencing the types of organisms that live in a body of water.

Secchi Disk Transparency - The mean depth of the point where a weighted white disk, 20 cm in diameter, disappears when viewed from the shaded side of a vessel and that point where it reappears upon raising it after it has been lowered beyond visibility. The Secchi disk transparency is essentially a function of the reflection of light from its surface and is therefore influenced by the absorption characteristics of both the water and its dissolved and particulate matter.

Selenium (Se) - Selenium is a metal found in natural deposits as ores containing other elements. The greatest use of selenium compounds is in electronic and photocopier components, but they are also widely used in glass, pigments, rubber, metal alloys, textiles, petroleum, medical therapeutic agents, and photographic emulsions. The toxicity of selenium depends on whether it is in the biologically active oxidized form, which occurs in alkaline soils. These conditions can cause plant uptake of the metal to be increased. It is known that selenium accumulates in living tissues.

Silver (Ag) - Silver is a very ductile and malleable (slightly harder than gold) metal with a brilliant white metallic luster that can take a high degree of polish. Silver is found in native form; combined with sulfur, arsenic, antimony, or chlorine and in various ores such as argentite (Ag2S), horn silver (AgCl), and pyrargyrite (Ag3SbS3). This metal can also be produced during the electrolytic refining of copper.

Sodium (Na) - Sodium occurs with silicates and with salt deposits. Sodium compounds are used in many applications, including caustic soda, salt, fertilizers, and water treatment chemicals. The ratio of sodium to total cations is important in agriculture and human physiology.

Sulfate (SO4-2) - Sulfates can be naturally occurring or the result of municipal or industrial discharges. When naturally occurring, they are often the result of the breakdown of leaves that fall into a stream, of water passing through rock or soil containing gypsum and other common minerals, or of atmospheric deposition. Problems caused by sulfates are most often related to their ability to form strong acids which can change pH.

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Tetrachloroethylene (PCE) - PCE is a colorless organic liquid with a mild, chloroform-like odor. Its greatest use is in the textile industry and as a component of aerosol dry-cleaning products. PCE released to soil will readily evaporate or may leach slowly to the groundwater. Its break down by soil microbes is slow. PCE released to water will primarily evaporate and has little potential for accumulating in aquatic life.

Toluene - Toluene is an organic liquid with a sweet, benzene-like odor. The largest chemical use for toluene is to make benzene and urethane. Toluene released to soil will be lost by evaporation from near-surface soil and by leaching to the groundwater. Its breakdown by soil microbes is slow. Toluene evaporates within a few hours when released to water and it has little tendency to accumulate in aquatic life.

Total Dissolved Solids (TDS) - Dissolved solids refer to minerals in solution. Waters with high dissolved solids generally are of inferior palatability. Highly mineralized waters also are unsuitable for many industrial applications.

Total Kjeldahl Nitrogen (TKN) - TKN is the most common analysis run to determine the amount of organic nitrogen in water. The test includes ammonium and organic nitrogen. Molecules containing organic nitrogen (e.g., simple amino acids, algal-derived humic substances) have been implicated as disinfection by-product precursors and membrane foulant materials.

Total Phosphorus (TP) - TP is a measurement of all forms, both particulate and dissolved, of phosphorus in water.

Total Suspended Solids (TSS) - Suspended solids refers to matter floating in water or wastewater. Solids may affect water or effluent quality adversely in a number of ways. Waters high in suspended solids may be aesthetically unsatisfactory for such purposes as bathing.

Transparency - A measure of the distance of the vertical penetration of light in lakes.

Trichloroethlyene - Trichloroethylene is a colorless or blue organic liquid with a chloroform-like odor. The greatest use of trichloroethylene is to remove grease from fabricated metal parts and some textiles. Trichloroethylene released to soil will either evaporate or leach into ground water. If released to water, it will also quickly evaporate. It has only a moderate potential to accumulate in aquatic life.

Turbidity - Turbidity in water is caused by suspended and colloidal matter such as clay, silt, finely divided organic and inorganic matter, plankton, and other microscopic organisms. Clarity of water is important in producing products for human consumption and in many manufacturing operations.

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Vanadium (V) - Vanadium is a soft and ductile, silver-grey metal. In biology, a vanadium atom is an essential component of some enzymes, particularly the vanadium nitrogenase used by some nitrogen-fixing micro-organisms.

Volatile Organic Compounds (VOCs) - Many organic compounds have been detected in ground and surface waters. Contamination may be due to past practice of on-site disposal of domestic and industrial wastes or to illegal discharges. Organohalides, particularly trihaolmethanes, are present in most chlorinated water systems. Toxicological studies on animals have shown that some of these organics have the potential to cause birth defects and cancer.

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Water Temperature - Water temperature is a function of ambient air temperatures and is one of the most biologically important parameters affecting dissolved oxygen saturation, biological growth rates, rates of chemical and biological reactions and the solubility of particulate compounds. Temperature readings are used in the calculation of various forms of alkalinity, in studies of saturation and stability with respect to calcium carbonate, in the calculation of salinity, and in general laboratory operations.

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Zinc (Zn) - Zinc is a moderately-reactive bluish-white metal. Zinc is an essential element, necessary for sustaining all life.

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