Glossary : Water Quality
  • A

  • 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.

  • Acceptable daily intake

    Acceptable daily intake (ADI) is the chemical ingestion level determined by combining the maximum No-Observed-Adverse-Effect-Level (NOAEL) with the addition of an uncertainty (safety) factor. Chemicals with ADI levels usually are not considered or suspected to be carcinogens. This classification results from toxicity data collected during prolonged ingestion studies conducted on a number of animals.

  • Acidity

    Acidity -The base neutralizing capacity of a water is known as acidity. Acids contribute to corrosiveness influence chemical reactions and chemical/biological processes. Acidity is determined using a titrametric or potentiometric method.

  • Acre-foot

    Acre-foot is the volume of water (325 851 gallons of water) required to cover one acre of land with 12 inches of water.

  • Adsorption

    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

    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

  • Aluminum(Al):

    There is no published Maximum Contaminant Level (MCL) but 0.2 mg/L is considered safe. Elevated aluminum is believed to be associated with forms of dementia such as: Alzheimer

  • Ammonia (NH4):

    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

    Anion is a negatively charged chemical. Nitrate and chloride (Cl-) are examples of anions.

  • Anion exchange

    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):

    Antimony (Sb): The maximum contaminant level is 0.006 mg/L. Elevated levels of antimony can increase blood cholesterol and decrease blood glucose.

  • Aquifer

    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.

  • Arsenic (As):

    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 your toenails and fingernails. For freshwater the concentration should be less

  • Artificial recharge

    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.

  • B

  • Barium (Ba):

    Barium (Ba):The MCL is 2 mg/L. Barium can increase blood pressure.

  • Baseflow

    Baseflow is that part of streamflow derived from groundwater flowing into a stream.

  • Beryllium (Be):

    Beryllium (Be): The MCL is 0.004 mg/L and it can cause intestinal lesions.

  • Biological Oxygen Demand (BOD)

    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 O/L). BOD 5 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

  • C

  • Cadmium (Cd):

    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):

    Calcium (Ca): No specific recommendation but high calcium is associated with hardness total dissolved solids problems and can cause aesthetic problems.

  • Capillary fringe

    Capillary fringe is a zone of partially saturated material just above the water table. The depth of the fringe depends upon the size and distribution of the pore spaces within the geologic formation.

  • Cation

    Cation is a positively charged chemical. For example calcium (Ca+2) and Magnesium (Mg+2) are cations.

  • Cation exchange

    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+2) ion.

  • 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

  • Chloride (Cl)

    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

  • Chlorine

    Chlorine: 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 great 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.

  • Conductivity

    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

  • Cone of depression

    Cone of depression is a depression in groundwater levels around a well in response to groundwater withdrawal or pumping water.

  • Confined aquifer (artesian aquifer)

    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