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  • Absorption is the process by which chemicals in gaseous, liquid or solid phases are incorporated into and included within another gas, liquid, or solid chemical. For example, sponges absorb water.
  • Acidity is defined as the base neutralizing capacity of water. Acids contribute to corrosiveness, influence chemical reactions and chemical/biological processes. Acidity is determined using a titrimetric or potentiometric method.
  • Adsorption is the adherence of gas molecules, ions or solutions to the surface of solids. For example, odors from freezers and refrigerators are adsorbed to baking soda.
  • Advection is the process by which chemicals and heat are transported along with the bulk motion of flowing gas or liquid. For example, nitrates move through soils and aquifer formations due predominantly to the bulk motion or movement of water.
  • Alkalinity: The acid neutralizing capacity of a water is known as alkalinity. For surface waters alkalinity has been called "The Protector of the Stream", since the alkalinity of the water rests sudden changes in the pH of the stream associated with the influx of acid deposition, water containing organic acids, groundwater discharges or industrial wastes.
    Most surface waters have alkalinity value < 200 mg CaCO3/L, but in limestone areas the alkalinity can be greater than 1000 mg CaCO3/L. In some cases, pristine surface water have very low alkalinity and therefore they would be adversely impacted by acid mine drainage and acid rain. The alkalinity of precipitation can be from 1 to about 10 mg CaCO3/L. Typically the best alkalinity for aquatic life is between 100 and 120 mg CaCO3/L. Alkalinity is determined using a titrimetric or potentiometric method.
  • Aluminium (Al): There is no published Maximum Contaminant Level (MCL), but 0.2 mg/L is considered safe. Elevated aluminium is believed to be associated with forms of dementia, such as: Alzheimer’s.
  • Ammonia (NH3): There is no MCL established for ammonia. Ammonia is very toxic to fish and aquatic life. Ammonia concentrations of 0.06 mg/L can cause gill damage in fish and 0.2 mg/L is lethal to trout. Concentrations in excess of 0.1 mg/L suggest domestic or agricultural sources of waste.
  • Anion is a negatively charged chemical. Nitrate (NO3-) and chloride (Cl-) are examples of anions.
  • Anion exchange is the chemical process where negative ions of one chemical are preferentially replaced by negative ions of another chemical. In water treatment, the net effect is the removal of an unwanted ion from a water supply. For example, some municipalities are installing anion exchange systems to remove nitrate from their water supplies.
  • Antimony (Sb): The maximum contaminant level is 0.006 mg/L. Elevated levels of antimony can increase blood cholesterol and decrease blood glucose.
  • Aquifer is the saturated underground formation that will yield usable amounts of water to a well or spring. The formation could be sand, gravel, limestone or sandstone. The water in an aquifer is called groundwater. A saturated formation that will not yield water in usable quantities is called an aquiclude. Most Pennsylvania aquifers may be categorized into confined and unconfined aquifers.
    • Confined aquifer (artesian aquifer) is the saturated formation between low permeability layers that restrict movement of water vertically into or out of the saturated formation. Water is confined under pressure similar to water in a pipeline. Drilling a well into this type of aquifer is analogous to puncturing a pressurized pipeline. In some areas confined aquifers produce water without pumps (flowing artesian well). When pumping from confined aquifers, water levels often change rapidly over large areas. However, water levels will generally recover to normal when pumping ceases.
    • Unconfined aquifer (water table aquifer) is the saturated formation in which the upper surface fluctuates with addition or subtraction of water. The upper surface of an unconfined aquifer is called the water table. Water, contained in an unconfined aquifer, is free to move laterally in response to differences in the water table elevations.


  1. Arsenic (As): The MCL for arsenic is 0.01 mg/L. Arsenic is highly toxic and its prevalence is due to the natural occurrence of this metal and past use of arsenic in pesticides. Arsenic poisoning typically makes people feel tired and depressed and this poisoning is also associated with weight loss, nausea, hair loss and marked by white lines across toenails and fingernails. For freshwater the concentration should be less than 0.01 mg/L.
  2. Artificial recharge is the unnatural addition of surface waters to groundwater. Recharge could result from reservoirs, storage basins, leaky canals, direct injection of water into an aquifer or by spreading water over a large land surface.


  • Barium (Ba):The MCL is 2 mg/L. Barium can increase blood pressure.
  • Beryllium (Be): The MCL is 0.004 mg/L and it can cause intestinal lesions.
  • Biological Oxygen Demand (BOD) : BOD is typically reported as 5 day BOD and ultimate BOD at 20 °C and reported as milligrams of oxygen consumed per liter (mg O2/L). BOD5 is used by regulatory agencies for monitoring wastewater treatment facilities and monitoring surface water quality. BOD is the biochemical oxygen demand of the water and it is related to the concentration of the bacterial facilitated decomposable organic material in the water. A sample with a 5 day BOD between 1 and 2 mg O2/L indicates a very clean water, 3.0 to 5.0 mg O2/L indicates a moderately clean water and > 5 mg O2/L indicates a nearby pollution source. BOD is a laboratory test that requires a oxygen sensing meter, incubator, nitrifying inhibitors and a source of bacteria.


  • Cadmium (Cd): The MCL for cadmium is 0.01 mg/L. Cadmium poisoning is associated with kidney disease and hypertension and possibly mutations. For freshwater the concentration should be less than 0.0004 mg/L.
  • Calcium (Ca): No specific recommendation, but high calcium is associated with hardness, total dissolved solids problems and can cause aesthetic problems.
  • Cation is a positively charged chemical. For example, calcium (Ca+2), and magnesium (Mg+2) are cations.
  • Cation exchange is a process where positively charged ions of one chemical are preferentially replaced by positive ions of another chemical. For example, water softeners replace Ca+2, and Mg+2 ions with the sodium (Na+) ion.
  • Chloride (Cl-): It is one of the major anions found in water and wastewater. The recommended maximum contaminant level is 250 mg/L, since the chloride ion imparts a salty taste to the water. If ions of calcium and magnesium are present, the chloride ion may not impart a salty taste until over 1000 mg/L. In addition to human and animal waste, sources of chloride can include natural geological formations, road salt storage and applications, oil/natural base drilling, and saltwater intrusions. High levels of chloride can attack and weaken metallic piping and fixtures and inhibit the growth of vegetation. Chloride ion is detected using a titrimetric or potentiometric method.
  • Chlorine (Cl2): Chlorine, in one of a number of forms, is added to water to destroy or deactivate disease-causing microorganisms and is the mostly widely used disinfectant in the United States. Elevated chlorine levels can create aesthetic problems (strong taste and odor) and if organic matter is present it can result in the creation of trihalomethanes, which are potentially carcinogenic with target organs including the liver and kidney.
  • Chemical Oxygen Demand (COD): COD is used as a measure of the oxygen equivalent of the organic matter content of the sample. Only the organic matter that is susceptible to oxidation by strong chemical oxidant. COD is typically used when there are industrial wastewater sources, comparing biological to chemical oxidation in the selection of treatment process and performances or depending on the waste stream it can provide insight into the concentration of reduced inorganic metal, such as ferrous iron, sulfide, and manganese.
  • Chromium (Cr): The MCL is 0.05 mg/L. The impact of chromium is not clearly defined, but it is known to adversely impact aquatic organisms.
  • Conductivity: The theoretical definition of conductivity is the "reciprocal of the resistance of a cube of a substance 1 cm on a side at a specified temperature". Typically the units of measure are microhms/cm (uohms/cm) or microsiemens/cm (uS/cm). Conductivity or specific conductance is a measure of the ability of a fluid to carry a charge which is directly related to the concentration of dissolved substances. As the total dissolved substances in the water increases, the conductivity of the water also increases. For more information see Total Dissolved Solids.
  • Contaminant is any unnatural biological, chemical, physical or radiological substance or matter contained in water. Tri-chloroethylene (TCE) is a synthetic cleaning solvent sometimes found in groundwater near manufacturing sites.
  • Copper (Cu): The MCL is 1 mg/L. At 1 mg/L, the water may taste bitter and is highly toxic and may disrupt the metabolic processes, especially for children. For freshwater the concentration should be less than 0.036 mg/L.


  • Diffusion is a process where heat or chemicals are transported in response to differences in chemical concentration or temperature. Movement is from high concentration (or temperature) to low concentration (or temperature). This process could involve liquids, gases and solids.
  • Discharge area is an area where groundwater moves toward or is delivered to the soil surface. Groundwater can flow into springs or seeps; contribute baseflow to streams; or provide supplemental water for plant use.
  • Dispersion is the process whereby a chemical, contained in water, deviates from the path that would be expected due to bulk flow. In the process the chemical is mixed with surrounding liquids, causing its concentration to be reduced.
  • Distillation is a two-stage water treatment method: 1) the liquid is boiled, producing water vapor; 2) the water vapor is condensed, leaving most contaminants behind. Distillation can be used to remove inorganic chemicals, some non-volatile organic chemicals and bacteria.
  • Drainage is the process of transporting surface water over a land area to a river, lake or ocean (surface drainage), or removal of water from a soil using buried pipelines that are regularly spaced and perforated (subsurface drainage).


  • Effluent is the discharge of a contaminant or contaminants with water from animal production or industrial facilities or wastewater treatment plant.
  • Erosion is the process or series of processes that removes soils, crop residues and organic matter from the land surface in runoff waters or by wind. Water droplets begin the erosion process by detaching soil particles. Runoff waters transport the detached particles to local and regional streams or lakes. Soil erosion represents the single largest source of nonpoint pollution in the United States.
  • Eutrophication is the process of surface water nutrient enrichment causing a water body to fill with aquatic plants and algae. The increase in plant life reduces the oxygen content of the water. Eutrophic lakes often are undesirable for recreation and may not support normal fish populations.


  • Field capacity is the amount of water a soil contains after rapid drainage has ceased. It is the water content following a period of gravity drainage without the addition of water.
  • Fecal coliform is a portion of the coliform bacteria group originating in the intestinal tract of warm-blooded animals that pass into the environment as faeces. Fecal coliform often is used as an indicator of the bacteriological safety of a domestic water supply.
    The fecal coliform bacterial density is determined using the membrane filtration technique. The MF procedure uses an enriched lactose medium and an incubation temperature of 44.5 + 0.2°C. Fecal coliform is bacteria typically found in the faeces of warm blooded mammals. Fecal coliform colonies produced by the M-FC medium are blue, while non-coliform colonies are pale yellow, gray or cream color. Since fecal coliform is found in mammalian waste, it is recommended that fecal coliform be absent from potable water.
  • Fecal Streptococcus: The fecal streptococcus group consists of a number of species of the genus Streptococcus, such as: S. faecalis, S. faecium, S. avium, S. bovis, S. equinus, and S. gallinarum. Fecal Streptococci are typically found in the gastrointestinal tract of warm blooded animals. Due to the variation in survival rates the ratio of FC/FS should not be used as a means of differentiating human and animal sources of bacterial contamination. Fecal streptococcus colonies produced by the KF-Streptococcus broth are red. For potable water, the fecal streptococcus should be absent.


  • Groundwater (sometimes written as two words) is water that occupies voids, cracks, or other spaces between particles of clay, silt, sand, gravel or rock within the saturated formation.
  • Groundwater recharge is the process where water enters the soil and eventually reaches the saturated zone. Recharge varies from place to place due to the amount of rainfall, infiltration and surface vegetation.


  • Hardness: The hardness of a water is a measure of the concentration of the multivalent cations (positively charged particles) in the water, but primarily it is equivalent to the calcium and magnesium concentration of the water. Hardness is typically reported as mg /L as CaCO3 (calcium carbonate), but it may also be reported as grains per gallon (1 gpg (US) = 17.12 mg CaCO3/L). Hardness classification: Soft: 0 to 17 mg CaCO3/L; Slightly Hard: 17 to 60 CaCO3/L; Moderately Hard 60 to 120 CaCO3/L; Hard 120 to 180 CaCO3/L; and Very Hard > 180 CaCO3/L.
  • Hydraulic conductivity is a term used to describe the ease with which water moves through soil or a saturated geologic material. Hydraulic conductivity is influenced by the type of material comprising the formation (sand, gravel, rock, limestone, sandstone, clay), the slope of the water table, the type of fluid, and the degree to which existing pores are interconnected.
  • Hydraulic gradient is the slope of the water surface in an aquifer. The hydraulic gradient indicates the direction groundwater will flow. Water always flows from higher water table elevations to lower water table elevations. All other factors being equal, flow is greater when the hydraulic gradient is steeper.
  • Hydrologic cycle describes the constant movement of water above, on, and below the Earth's surface. Processes such as precipitation, evaporation, condensation, infiltration and runoff comprise the cycle. Within the cycle, water changes forms in response to the Earth's climatic conditions.


  • Infiltration is the downward entry of water into the soil. The infiltration rate is a function of surface wetness soil texture, surface residue cover, irrigation application or precipitation rate, surface topography and other factors.
  • Iron (Fe): The MCL is 0.3 mg/L. Iron is a secondary drinking water standard and primarily regulated because of the aesthetic problems associated with elevated iron concentrations.


  • Leaching is the removal of dissolved chemicals from soil by the movement of a liquid (like water).
  • Lead (Pb): The MCL is 0.05 mg/L. Symptoms of lead poisoning start as: abdominal pains, constipation, fatigue, depressed appetite and decrease endurance, but long-term exposure may lead to nerve and kidney damage and anemia.


  • Magnesium (Mg): No specific recommendation, but high calcium is associated with hardness, total dissolved solids problems and can cause aesthetic problems.
  • Manganese (Mn): The MCL is 0.05 mg/L. Manganese is primarily regulated because of the aesthetic problems associated with elevated levels of manganese, i.e., a secondary drinking water standard. Elevated manganese levels can disrupt the nerve system and regeneration of hemoglobin. For freshwater the concentration should be less than 1.5 mg/L.
  • Maximum contaminant levels (MCLs) are legally enforceable drinking water standards required by the Safe Drinking Water Act. Standards set by the Environmental Protection Agency establish the maximum permissible concentration of selected contaminants in public water supplies. Contaminants are included on the list if they pose a public health risk. For example, 10 ppm is the MCL for nitrate-nitrogen (NO3-N).
  • Mercury (Hg): The MCL is 0.002 mg/L for organic mercury. Mercury has been associated with kidney disease. For freshwater the concentration should be less than 0.00005 mg/L.


  • Nickel (Ni): MCL has not been established but for freshwater the concentration should be less than 0.1 mg/L. Element is detected using flame atomic absorption. Nickel may cause dermatitis and nasal irritation.
  • Non-point source (NPS) pollution is the source of surface or groundwater pollution originating from diffuse areas without well-defined sources. The most common examples of NPS are chemicals that enter surface water during runoff events from crop land and turfgrass, and soil erosion from cultivated cropland and construction sites.


  • Part-per-million (ppm) is a measure of concentration of a dissolved material in terms of a mass ratio (milligrams per kilogram, mg/kg). One part of a contaminant is present for each million parts of water. For water analysis, parts per million often is presented as a mass per unit volume (milligrams per liter, mg/L). There are one million milligrams of water in one liter.
  • pH is a numerical measure of the acidity or alkalinity of water. The pH scale ranges from 1 (acidic) to 14 (alkaline). A pH of 7 is neutral. The technical definition of pH is, measure of the activity of the hydrogen ion (H+) and is reported as the reciprocal of the logarithm of the hydrogen ion activity. Therefore, a water with a pH of 7 has 10-7 moles per liter of hydrogen ions; whereas, a pH of 6 is 10-6 moles per liter. The pH scale ranges from 0 to 14.
  • Phosphate (PO43-): There is no MCL for phosphate. In surface waters, phosphate is typically a limiting plant nutrient. The recommended maximum concentration in rivers and streams is 0.1 mg/L of total phosphate.
  • Point source (PS) pollution is the source of surface or groundwater pollution that originates from a well-defined source. Examples include: industrial effluent; large animal containment facilities; municipal wastewater treatment discharges; or chemical spills. Point sources commonly are associated with pipeline discharges of some type.
  • Pollutant is any unwanted chemical or change in physical property that renders a water supply unfit for its intended use.
  • Potable water supply is a source of water that can be used for human consumption.
  • Precipitation is the process where water vapor condenses in the atmosphere to form water droplets that fall to the earth as rain, sleet, snow or hail. In Turkey long-term annual precipitation varies from 300 mm to 2000 mm.
  • Pumping water level is the water level in a well when the pump is operating and water is being removed.


  • Recharge area is the area where water predominantly flows downward through the unsaturated formation (zone) to become groundwater.
  • Runoff is precipitation or irrigation water that does not infiltrate but flows over the land surface toward a surface drain, eventually making its way to a river, lake or an ocean.


  • Saturated formation (zone) is the portion of a soil profile or geologic formation where all voids, spaces or cracks are filled with water. No air is present. There may be multiple water-bearing formations within a saturated formation. These water-bearing formations often are separated by layers of clay or other impermeable layers.
  • Seepage is the movement of water into or through a porous material. Seepage occurs from canals, ditches and other water storage facilities. It sometimes is used to describe water escaping from municipal landfill sites.
  • Selenium (Se): The MCL is 0.05 mg/L. Selenium is associated with hair or fingernail loss, numbness of fingers and toes, and circulatory problems. For freshwater the concentration should be less than 1.5 mg/L.
  • Silver (Ag): The MCL is 0.10 mg/L. Silver is associated with causing discoloration of the skin. For freshwater the concentration should be less than 0.0003 mg/L.
  • Sodium (Na): No MCL has been set. For individuals on low sodium diets, a general recommendation of 20 mg/L is used.
  • Specific capacity expresses the productivity of a well. Specific capacity is obtained by dividing the well discharge rate by the well drawdown while pumping.
  • Spring is the point of natural groundwater discharge to a soil surface, river, or lake.
  • Static water level is the water level in a well located in an unconfined aquifer when the pump is not operating. The static water level is the surface of the water-bearing formation and typically is synonymous with the water table.
  • Strontium (Sr): No MCL has been set, but the element is analyzed using nitrous oxide -acetylene flame. The primary concern is the presence of a radioactive form, known as Strontium-90.
  • Sulfate (SO42-): The drinking water limit is 250 mg/L. Sulfate (SO42-) is widely distributed in natural waters, but is typically less than a few mg/L. The primary sources of sulfate in surface waters and groundwater include: acid mine drainage, acid deposition and mineral oxidation. A standard is set because of taste, aesthetic problems and laxative effects.
  • Sulfite (SO32-): May occur in boilers and boiler feed waters treated with sulfite to control dissolved oxygen levels, natural waters containing industrial waste and in wastewater treatment plant effluents using sulfur dioxide to dechlorinate the effluent.


  • Total Kjeldahl Nitrogen (TKN): There is no MCl for total kjeldahl nitrogen. This parameter is used to measure the total amount of organic nitrogen and is typically used for surface water and groundwater investigations associated with domestic or agricultural contamination.
  • Total dissolved solids (TDS) is a water quality parameter defining the concentration of dissolved organic and inorganic chemicals in water. After suspended solids are filtered from water and water is evaporated, dissolved solids are the remaining residue. Dissolved solids commonly found in water are calcium, magnesium, sodium, potassium, bicarbonate, sulfate, chloride and silica. Total dissolved solid concentrations depend on the geologic material water passes through in the saturated and unsaturated zone, and the quality of the infiltrating water. Total dissolved solid contents could range from less that 100 ppm to greater than 1,000 ppm in streams.
  • Turbidity: Turdidity is a measure of the cloudiness or opaqueness of the water and is measured in Nephelometric Turbidity Units (NTU). The turbidity is influenced by the amount and nature of suspended organic and inorganic material in water. Typically, the higher the concentration of the suspended material, the greater the turbidity. The value of 1 NTU is recommend for drinking water, since higher turbidities could cause aesthetic problems or inhibit the ability of a system to disinfect the water. The source of turbidity could be fine sand, silt and clay (i.e., soil separates); organic material, particles of iron and manganese or other metal oxides, rust from corroding piping or carbonate precipitates. Turbidity measurements are typically not made on surface water sources - see Total suspended solids.
  • Total Solids: The total amount of solids in the sample, which includes: dissolved, suspended, and volatile.
  • Total Suspended Solids: A fixed volume of sample is filtered through a pre-weighed and washed glass fiber filter. The filter is then rinsed and dried at 103 to 105 °C. The change in the weight of the filter represents the weight of suspended material. This test is typically done for surface water supplies and wastewater treatment plants. For drinking water, turbidity is parameter that is typically monitored.
  • Total Dissolved Solids Is determined by filtering a measured volume of sample through a standard glass fiber filter. The filtrate (i.e., filtered liquid) is then evaporated to dryness at a constant temperature of 180 °C. High total dissolved solids may affect the aesthetic quality of the water, interfere with washing clothes and corroding plumbing fixtures. For aesthetic reasons, a limit of 500 mg dissolved solids/L is typically recommended for potable water supplies.
  • Total Volatile Solids: The residue for previous testing is then ignited at a temperature of 500 °C. The change in the weight represents the amount of suspended or dissolved solids that are organic in nature or volatilized. The parameter is typically used in wastewater treatment plants because it provides an estimate of the organic matter content within the waste stream.


  • Unsaturated formation (vadose zone) is the soil or other geologic material usually located between the land surface and a saturated formation where the voids, spaces or cracks are filled with a combination of air and water.


  • Vanadium (V): Currently there is no specific MCL for vanadium. Vanadium may cause respiratory problems and inhibition of Na and K in ATP production.


  • Watersheds are regional basins drained by or contributing water to a particular point, stream, river, lake or ocean. Watersheds range in size from a few acres to large areas of the country.
  • Water table is the upper level of a saturated formation where the water is at atmospheric pressure. The water table is the upper surface of an unconfined aquifer.


  • Zinc (Zn): The MCL is 5 mg/L, because of problems with the aesthetic quality due to the taste of zinc.



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