# EPACriteria2

criteria:
Drinking Water Standards
Primary MCL
(health based + technology & economics)


criteria:
Freshwater Aquatic Life Protection
Continuous Concentration
(4-day Average)

notes:
a) The freshwater criterion is expressed as a function of hardness (mg/L) in the water column. The value given here corresponds to a hardness of 100 mg/L. The criterion for other hardness concentrations may be calculated per the equation CCC=exp(0.7409[ln(hardness)]-4.719)*CF, where CF= 1.101672-[(ln(hardness)*0.041838].


criteria:
Freshwater Aquatic Life Protection
Maximum Concentration 
(1-hour Average)

notes:
a) The freshwater criterion is expressed as a function of hardness (mg/L) in the water column. The value given here corresponds to a hardness of 100 mg/L. The criterion for other hardness concentrations may be calculated per the equation CMC=exp(1.0166[ln(hardness)]-3.924)*CF, where CF=1.136672-[(ln(hardness)*0.041838].


criteria:
Saltwater Aquatic Life Protection
Continuous Concentration
(4-day Average)


criteria:
Saltwater Aquatic Life Protection
Maximum Concentration 
(1-hour Average)


criteria:
Drinking Water Standards
Secondary MCL
(taste & odor or welfare-based)


criteria:
Human Health & Welfare Protection
Public Health Effects 
(other than cancer risk)
Water & Fish Consumption


criteria:
Human Health & Welfare Protection
Taste & Odor or Welfare


notes:
a) Aquatic life freshwater quality criteria are calculated using the Biotic Ligand Model, a metal bioavailability model.


criteria:
Recommended criteria not yet developed for ecoregion


criteria:
Human Health & Welfare Protection
Water & Fish Consumption


criteria:
Freshwater Aquatic Life Protection
 Maximum Concentration
(Instantaneous)


notes:
a) Recommended criteria not yet developed for ecoregion


criteria:
Human Health & Welfare Protection
One-in-a-Million Incremental Cancer Risk Estimate
Water & Fish Consumption


criteria:
Human Health & Welfare Protection
One-in-a-Million Incremental Cancer Risk
Fish Consumption Only


criteria:
Human Health & Welfare Protection
Taste & Odor Welfare


criteria:
National Primary Drinking Water Regulations Maximum Contaminant Level


criteria:
Coldwater Criteria, Early Life Stages
water column, 30-day mean


criteria:
Coldwater Criteria, Early Life Stages
water column, 7-Day mean


criteria:
Warmwater Criteria, Early Life Stages
7-Day Mean Minimum


criteria:
Warmwater Criteria, Early Life Stages
1-Day Minimum


criteria:
Warmwater Criteria, Other Life Stages
30-Day Mean

notes:
30-Day Mean
(b) Includes all embryonic and larval stages and all juvenile forms to 30-days following hatching.


criteria:
Warmwater Criteria, Other Life Stages
7-Day Mean

notes:
7-Day Mean
(b) Includes all embryonic and larval stages and all juvenile forms to 30-days following hatching.


criteria:
Warmwater Criteria, Other Life Stages
7-Day Mean Minimum


criteria:
Warmwater Criteria, Other Life Stages
1-Day Minimum


criteria:
Coldwater Criteria, Other Life Stages
30-Day Mean


criteria:
Coldwater Criteria, Early Life Stages
water column, 7-Day Mean Minimum


criteria:
Coldwater Criteria, Early Life Stages
water column, 1-Day Minimum


criteria:
Coldwater Criteria, Early Life Stages
intergravel, 30-Day Mean


criteria:
Coldwater Criteria, Early Life Stages
intergravel, 7-Day Mean


criteria:
Coldwater Criteria, Early Life Stages
intergravel, 7-Day Mean Minimum


criteria:
Coldwater Criteria, Early Life Stages
intergravel, 1-Day Minimum


criteria:
Warmwater Criteria, Early Life Stages
30-Day Mean


criteria:
Warmwater Criteria, Early Life Stages
7-Day Mean


criteria:
Human Health & Welfare Protection
Public Health Effects 
One-in-a-Million Incremental Cancer Risk Estimate
Water & Fish Consumption


criteria:
Human Health & Welfare Protection
Public Health Effects 
One-in-a-Million Incremental Cancer Risk Estimate Fish Consumption Only


criteria:
Human Health & Welfare Protection
Public Health Effects 
(other than cancer risk)
Fish Consumption Only


# labMethods_data

intSrcOfUncertainty:
1.  High dissolved solids in samples can bias results. 
2.  Wavelength interference can occur from high concentrations of elements with similar wavelegths (200.7)
Other notes: 
1.  Use of a high solids nebulizer, dillution, use of an internal standard(s), 200.8 can use a reaction cell to suppress solids. 
2.  Multiple wavelengths can be used to determine interference.

otherNotes:
1.  Use of a high solids nebulizer, dillution, use of an internal standard(s), 200.8 can use a reaction cell to suppress solids.  2.  Multiple wavelengths can be used to determine interference.


otherNotes:
1.  Use of a high solids nebulizer, dillution, use of an internal standard(s).  2.  Multiple wavelengths can be used to determine interference.


intSrcOfUncertainty:
Method tests for HEM (Hexane-extractable Material),any compound which is soluble in the hexane extraction solvent will be reported as O&G.  Silica-gel treatment can be used to remove the non-hydrocarbon portion of the sample.


intSrcOfUncertainty:
Method tests for any compound which is ignitable in the FID detector and falls within the rentention time windows of the RT marker, which marks the position of straight-chain Carbon compounds (GRO C6-C10 or C12, DRO C10-C20m and MRO C20-C36)


intSrcOfUncertainty:
Compensate for color and turbitity by using sample to zero spectrophotometer.


intSrcOfUncertainty:
EPA 300.0 Interferences can be caused by substances with tretention times that are similar to and overlap those of the anion of interest. Sample dilution can be used to solve most interference problems associated with retention times. Samples that contain particles larger than 0.45 microns should be filtered to  avoid interference and damage to column.


intSrcOfUncertainty:
Temperature can affect pH. Always use temperature correcting probe.


intSrcOfUncertainty:
For SM 4500 PE: Arsenates react with molybdate reagent to produce a blue color similar to that formed with phosphate. Concentrations as low as 0.1 mg/L interefere with phosphate determination.


intSrcOfUncertainty:
EPA 300.0 Interferences can be caused by substances with retention times that are similar to and overlap those of the anion of interest. Sample dilution can be used to solve most interference problems associated with retention times. Samples that contain particles larger than 0.45 microns should be filtered to  avoid interference and damage to column.                   For SM 4500 PE: Arsenates react with molybdate reagent to produce a blue color similar to that formed with phosphate. Concentrations as low as 0.1 mg/L interefere with phosphate determination.


intSrcOfUncertainty:
EPA 300.0 Interferences can be caused by substances with retention times that are similar to and overlap those of the anion of interest. Sample dilution can be used to solve most interference problems associated with retention times. Samples that contain particles larger than 0.45 microns should be filtered to  avoid interference and damage to column. For SM 4500 NO3-E: Low results may be obtained if high concentrations of copper or iron are present. Suspended matter can cause interference on spectrometer; prefilter or dilute samples.


intSrcOfUncertainty:
EPA 300.0 Interferences can be caused by substances with retention times that are similar to and overlap those of the anion of interest. Sample dilution can be used to solve most interference problems associated with retention times. Samples that contain particles larger than 0.45 microns should be filtered to  avoid interference and damage to column. For SM 4500 NO2-B: Low results may be obtained if high concentrations of copper or iron are present. Suspended matter can cause interference on spectrometer; prefilter or dilute samples.


intSrcOfUncertainty:
High nitrate values may result in low TKN values. If interference is suspected, dilute the sample.


intSrcOfUncertainty:
Excessive residue may form water-entrapping crust. Limit sample size to yield no more than 200 mg of residue. Thoroughly wash filter to remove dissolved material.


intSrcOfUncertainty:
Samples containing high concentrations of bicarbonate material require prolonged drying at 105 celcius. Limit total residue to 200 mg, dilute if necessary.


intSrcOfUncertainty:
Soluble versus particulate organics, settleable solids, oxidation of iron and sulfur compounds, lack of mixing, and heavy metals can affect the accuracy of measurements.


intSrcOfUncertainty:
Chlorides will produce high results, mercuric sulfate eliminates chloride interference.


intSrcOfUncertainty:
This procedure is applicable only to homogenous samples which can be reproducibly injected into apparatus  by syringe or pipet.


intSrcOfUncertainty:
Determined on a non-selective detector, ID based on retention time match with calibration standard


intSrcOfUncertainty:
1.  High dissolved solids in samples can bias results.
2.  Wavelength interference can occur from high concentrations of elements with similar wavelegths (200.7)
Other Notes: 1.  Use of a high solids nebulizer, dillution, use of an internal standard(s), 200.8 can use a reaction cell to suppress solids.
2.  Multiple wavelengths can be used to determine interference.


intSrcOfUncertainty:
1.  High dissolved solids in samples can bias results. 
2.  Wavelength interference can occur from high concentrations of elements with similar wavelegths (200.7)
Other notes: 1.  Use of a high solids nebulizer, dillution, use of an internal standard(s), 200.8 can use a reaction cell to suppress solids. 
2.  Multiple wavelengths can be used to determine interference.


# pollutants

formsAndSources:
In the environment, phosphorus typically occurs as part of a phosphate molecule (PO₄³⁻), which can be a free molecule (orthophosphate), part of inorganic molecules, or part of numerous organic molecules. Because of the many forms, phosphorus is usually reported as orthophosphate, dissolved phosphorus, or total phosphorus. Elevated concentrations of phosphorus can occur through weathering of certain minerals, but mostly occur through man-made inputs such as wastewater effluent, septic system seeps, and animal manure. Phosphorus compounds are typically added, along with other nutrients, to crops as fertilizer. Phosphorus may also be present in detregents, flame retardants, corrosion inhibitors, and plasticizers. Phosphorus compounds are also added as a nutrient necessary for bacterial growth in biological deicer treatment systems.  Both inorganic and organic phosphorus can be dissolved or associated with particulate organic matter.

enviroEffects:
In many surface waters, phosphorus is the limiting nutrient, so small increases in phosphorus can cause substantially accelerated growth of plants and algae. Algae blooms can cause decreased dissolved oxygen concentrations which can smother other aquatic life, and dead algae cells can alter streambed characteristics, impacting habitat for fish and other aquatic life. Because it is an element, phosphorus cannot be destroyed, but it is part of many transformation reactions that are naturally occurring. Unlike nitrogen, phosporus is not released as a gas. Plants can only uptake inorganic phosphorus, which becomes part of their biomass. Animals get phosphorus by ingesting plants and other animals. As organisms excrete waste or die, organic phosphorus is released back to the environment, where microbes break it down to inorganic phosphate, completing the cycle.

monitoringChallenges:
Samples designated for dissolved phosphorus and orthophosphate analysis must be field filtered (15 minute holding time).
Analysis holding time for orthophosphate is 48 hours.
Verify correlation among different methods intended to measure the same phosphorous parameter (Total P, or phosphate).

fieldMethods:
Orthophosphate may be measured in the field using the ascorbic acid method (EPA 365.3), the vanadomolybdophosphoric acid method (SM 4500-P C), or the stannous chloride method (SM 4500-P D). A reagent (either liquid or powder) containing ammonium molybdate and one of the above reducing agents reacts with orthophosphate in the sample to form a blue or yellow compound. The intensity of the color is directly proportional to the orthophosphate concentration in the water. Several manufacturers have field test kits that can be used to measure reactive phospate. Reactive phosphate  is an anlaysis intended to measure orthophosphate, but the analysis may measure small fractions of other forms of phosphorus. If PO₄ concentrations are less than 0.1 mg/L, then a field spectrometer or colorimeter is recommended over the use of a color comparator. Accuracy of measurements in field test kits can be variable at low concentrations. As a result, it is recommended for test kit methods that reactive phosphate measurements be correlated to orthophosphate measurements conducted by the EPA methods identified above.

Footnotes:
a) Recommended criteria not yet developed for ecoregion


formsAndSources:
Polycyclic aromatic hydrocarbons (PAHs) are a class of organic compounds characterized by two or more fused aromatic rings composed of carbon and hydrogen. Although PAHs can exist in over 100 combinations, EPA has identified 16 “priority PAHs” which are most commonly tested for by laboratories. These compounds are naphthalene, acenaphthylene, acenaphthene, fluorine, phenanthrene, anthracene, fluoranthene, pyrene, benz(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenz(a,h)anthracene, benzo(ghi)perylene and indeno(1,2,3-cd)pyrene. PAHs are hydrophobic compounds that sorb to suspended clay and organic particles and will typically settle out of the water column onto bottom sediments where they can persist for long periods of time. 

PAHs exist in heavy fractions of petroleum products and are created through incomplete burning of fossil fuels, wood, and other organic materials. They are used to make dyes, plastics, sealants, and wood preservatives. At airports, potential sources of PAHs include asphalt pavement sealcoats; fuel and oil spills and leaks; and aircrafts and ground vehicle maintenance and washing activities. PAHs may also be deposited at airports from atmospheric deposition from local, regional, and global hydrocarbon emissions.
 
Higher molecular weight PAHs (>3 aromatic rings) are relatively immobile. These are also less water-soluble, less volatile and more lipophilic (fat soluble) than lower molecular weight PAHs.  In the environment, PAHs with 3 or more aromatic rings sorb readily to particles in soil and water, especially clays and organic matter.  PAH concentrations in water are usually low relative to the concentrations in the bottom sediments due to the tendency to sorb to particles and settle in the water column.  Due to their hydrophobicity and specific gravity, PAHs that are not associated with solids are likely to behave like a dense non-aqueous phase liquid (DNAPL).

enviroEffects:
PAHs are persistent, bioaccumulative, and toxic to humans. PAHs are also moderately to highly toxic to aquatic life and birds.

monitoringChallenges:
Obtaining representative samples for PAH analysis in storm sewers can be a challenge based on the potential presence of PAHs in the liquid and attached to the solids. The tendency of solids to settle in airport stormwater pipes also leads to the need for a well thought through sampling procedure.


formsAndSources:
pH is measured on a scale from 1.0 to 14.0, and determines the activity of hydrogen ions in a sample (i.e., acidity or alkalinity of a sample). The pH scale is related directly to H⁺ and hydroxide (OH⁻) concentrations at a given temperature. Lower pH values correspond to acidic conditions, or a higher proportion of hydrogen ions relative to hydroxide ions, and higher pH values correspond to alkaline or basic conditions. Neutral waters are at pH 7.0 (i.e., equal components of hydrogen and hydroxide ions).    

Normal rain is slightly acidic because carbon dioxide (CO₂) dissolves into it forming weak carbonic acid, resulting in a pH of approximately 5.6 at typical atmospheric concentrations of CO₂. Acid rain, which forms as the result of higher than normal amounts of nitric and sulfuric acids in the atmosphere further lowers the pH. The pH of receiving waters is altered by introduction of ions that interact with hydrogen ions or hydroxide ions, causing the concentration of hydrogen ions to increase or decrease relative to hydroxide ions. 

Sources that can lead to low pH include mine sites, particularly where sulfur-bearing rock is present, acid-generating weathered rock (such as volcanic deposits, processes that can be expedited by acid rain), industrial processes including metal plating and circuit board manufacturing, agriculture, septic systems, landfills, and coal pile runoff.  Sources that can lead to high pH include industries and agriculture that use lime, lye, certain salts, and products containing these compounds, including cement production and soap production.  Runoff from natural and processed or mined limestone can also lead to discharges with high pH. At airports, the breakdown of deicing chemicals into volatile fatty acids can decrease the pH to as low as 3 to 5. This is typically an issue where water is pooled or stagnant.

enviroEffects:
pH is a primary factor governing the chemistry of natural water systems. The pH of water directly affects physiological functions of plants and animals and is therefore an important indicator of the health of a water system. The optimal range of pH for aquatic species is between 6.5 to 8.0, though pH values up to 9.0 are still considered within the normal range.  Low pH may cause damage to skin, gills, bones, and shell production in aquatic species.  Skin damage can lead to fungal and bacterial infection.  Water pH lower than 6.5 causes decreases in the number of species as well as populations of species, effects which are amplified as pH is lowered.  The effects of high pH are typically not as lethal as low pH, but pH above 9.5 will cause damage to gills, eyes, and skin of aquatic organisms over prolonged periods of exposure.
 
pH is also a water quality concern because of its impacts to the toxicity and chemical forms of other pollutants (e.g. partitioning of metals, toxicity of ammonia). For example, algal blooms that are often initiated by an overload of nutrients can cause pH to fluctuate dramatically over a few-hour period, greatly stressing local organisms. Even small shifts in the water’s pH can affect the solubility of some metals such as iron and copper. Such changes can influence aquatic life indirectly; if the pH levels are lowered, toxic metals in sediment can become dissolved in the water column.  Low pH can affect the stuctural integrity of concrete stormwater infrastructure.

monitoringChallenges:
Because pH samples have an extremely short holding time, pH must be measured within 15 minutes of collection.  As such, for regulatory compliance, pH should be measured in the field as laboratory analysis would be outside of holding time. An additional challenge related to pH testing in the field is proper calibration of field pH meters.
Online pH monitors should be checked for biofilms, which can significantly affect the pH reading.

relatedParameters:
Alkalinity measures the capacity of water to neutralize acids. It is a good measure of the sensitivity of a receiving water to acid inputs. Alkalinity is determined by a titration analysis and the measured value may vary significantly with the end point pH used for the titration.

fieldMethods:
pH should be measured in field using pH meter that utilizes EPA Method 120.1 or wide range litmus paper


formsAndSources:
Total petroleum hydrocarbons (TPH) is defined as the measurable amount of petroleum-based hydrocarbon in an environmental media. There are several hundred individual hydrocarbon chemicals defined as petroleum-based, and each petroleum product has its own mix of constituents. One reason for this is that crude oil, itself, varies in its composition. Some of this variation is reflected in the finished petroleum product. The acronym PHC (petroleum hydrocarbons) is widely used to refer to the hydrogen- and carbon-containing compounds originating from crude oil, but PHC should be distinguished from TPH, because TPH is specifically associated with environmental sampling and analytical results.

Some petroleum products are highly predictable (e.g., jet fuels) with specific fractions of defined components; others such as automotive gasolines, contain broader ranges of hydrocarbon types and amounts. For example, TPH quantified as gasoline range organics (GRO) corresponds to the range of alkanes (molecules consisting of hydrogen and carbon) from C₆ to C₁₀ and a boiling point range of approximately 60°C - 170°C. TPH quantified as diesel range organics (DRO) corresponds to the range of alkanes from C₁₀ to C₂₈ and a boiling point range of approximately 170°C - 430°C. Oil and grease is a measure of biodegradable animal greases and vegetable oils along with the relative non-biodegradable mineral oils.

TPH may enter the environment though production, transportation, use, storage or spills of petroleum products such as gasoline, diesel oil, aviation fuel and heating oil. There are numerous sources of TPH at airports including aircraft, ground vehicle, and equipment servicing/maintenance, fueling, and washing, and runway maintenance.

enviroEffects:
Aromatic hydrocarbons, ring molecules such as benzene, tend to be more soluble in water and less volatile than aliphatic hydrocarbons, chain molecules such as propane or butane. Some of the more soluble aromatic hydrocarbons may affect taste and odor of drinking water at very low levels. Fate and transport of TPH compounds differs depending on volatility and solubility. Toxicity of TPH varies depending on the combination of chemicals present in a given sample. The environmental effects of many hydrocarbons have not been studied in detail.

monitoringChallenges:
TPH constituents adhere to sampling containers and therefore samples must be collected directly into bottles as grab samples (i.e., TPH cannot be collected as a composite sample). In addition, a portion of the volatile fraction (such as for TPH-gasoline analysis) could be lost if composite sampling is performed.

relatedParameters:
BTEX (Benzene, Toluene, Ethylbenzene, and Xylenes) are a sub-group of TPH (TPH as gasoline). PAHs are often found in low concentrations in petroleum hydrocarbon mixtures.


formsAndSources:
Zinc is a naturally abundant element found in rocks and soil, from where it can be dispersed to air, water, plants, and animals via a variety of natural and human-influence processes. Zinc may exist as a dissolved or particulate-bound pollutant in stormwater and surface water bodies.  Common species of zinc include dissolved  ionic forms (Zn²⁺) and complexes with sulfates (ZnSO₄), carbonates (ZnCO₃), and organics (ZnDOM).  The relative proportions of these species is a function of water chemistry (pH in particular) and to a lesser degree, hydrology. Of these, complexes with organics (ZnDOM) and divalent Zn²⁺ (depending on site rainfall and runoff pH) are predominant in urban stormwater.

Zinc is primarily released into the environment through human activities. Emissions to air, water and soil can occur at all stages of production and processing of zinc, and from fuel combustion. Sewage treatment plants and disposal sites for industrial and household wastes can be sources of zinc levels harmful to the environment. Zinc is a component of many metallic alloys (e.g. brass) and non-metallic products such as tires. Corrosion and leaching of zinc-galvanized infrastructure, along with abrasion and wear of rubber tires can cause releases of zinc into soil and water. Uncontrolled releases may also occur from application of fertilizers or herbicides. Products made from galvanized steel (e.g., cars, roofs, fences, etc.), dry cell batteries, ointments (e.g. sunscreen), some vitamin/mineral dietary supplements, TV screens, cigarettes, watches, and zinc soaps may also contribute zinc to the environment. At airports, taxiways and runways (particularly touchdown areas), terminals and loading docks, runoff from fueling areas, and spent washwater from equipment maintenance are sources of metals in general.

enviroEffects:
Zinc can be toxic to aquatic and benthic organisms at relatively low concentrations. Factors such as receiving water hardness, dissolved oxygen and temperature influence the toxicity of zinc to aquatic life. While toxicity is primarily caused by bioavailable dissolved zinc species in the water column and interstitial pore spaces of sediment, partitioning between the solid and dissolved phases can be cyclic as conditions change due to runoff chemistry dynamics.

monitoringChallenges:
As with all metals, there is potential for sample contamination from the surrounding environment. If a high resolution analytical method is used (e.g., EPA 1600 series), EPA recommends using clean sampling protocols (i.e., “Clean Hands, Dirty Hands”) to prevent contamination.
 
Samples must be filtered for dissolved zinc within 15 minutes of sample collection. The filtered samples may be preserved in the field or transported to the laboratory for preservation.

Because zinc can have significantly different concentrations in the water column versus solids, the sample collection point should be well-mixed to account for both phases to get an accurate concentration in the flow stream.


formsAndSources:
Ethylene glycol and propylene glycol are the primary components in aircraft deicing and anti-icing fluids; some formulations of pavement deicers also use glycols. Other potential sources at airports include heat transfer fluids, automobile antifreeze, and hydraulic brake fluids. Ethylene glycol (C₂H₆O₂) and propylene glycol (C₃H₈O₂) are clear, colorless, odorless liquids that are miscible in water. Glycols are often monitored by airports to meet NPDES permit requirements. Some airports monitor glycols to support deicer management operations.

enviroEffects:
Ethylene and propylene glycol biodegrade under both aerobic and anaerobic conditions in a matter of days to weeks in air, water and soil. Aerobic microbial biodegradation is the most important environmental fate process affecting glycols in surface waters. The natural biodegradation of these chemicals may place high oxygen demands on aquatic ecosystems, causing a decrease in dissolved oxygen concentrations in receiving waters. Because glycols are miscible in water, they do not accumulate in aquatic biota. However, at sufficiently high concentrations they can cause acute and chronic toxicity in aquatic organisms. Ethylene glycol has high mobility in soil and the potential to leach to groundwater. Degrading glycols can produce odors. Anaerobic degradation of glycols can lower pH.

monitoringChallenges:
The principle monitoring challenge for glycols derived from deicing chemicals is the collection of representative samples. Glycol concentrations can vary by orders of magnitude because of the nature of deicing. Glycol analysis using EPA methods is also expensive, and generally requires an offsite laboratory.

relatedParameters:
Surrogate parameters are often used to indicate concentration of glycols in stormwater because of the cost and turn-around times of laboratory tests. Glycols are biodegradable and oxygen in the water is consumed as a part of the degradation process. When biodegradable compounds degrade, dissolved oxygen in the water is consumed and there is a resulting oxygen demand. The correlation between a glycol and chemical oxygen demand (COD) or total organic carbon (TOC) is strictly mathematical. The correlation between a glycol and biological oxygen demand (BOD) is based on analytical results and can be affected by the seed used in the analysis. Correlations are most accurate when deicer compounds are the primary source of BOD, COD or TOC in the samples and when deicer is found at high concentrations. Correlations are less accurate for samples containing a mixture of glycols, acetates, formates, or other constituents. Also, as the deicer concentration approaches the background concentration for COD or TOC, correlations become less reliable. To determine background effect on the correlation between COD or TOC and glycols at low glycol concentrations (less than 300 mg/L), a site-specific relationship based on many samples is needed and requires both the propylene glycol concentration and the COD or TOC concentration to determine the variability.

The following correlations may be used to estimate concentrations of untreated propylene glycol in stormwater where propylene glycol is the primary deicing compound used:
Propylene glycol concentration = 1.1 * BOD5 concentration
Propylene glycol concentration = 0.59 * COD concentration
Propylene glycol concentration = 2.1 * TOC concentration
These relationships are not valid for treated stormwater.

The following correlations may be used to estimate the concentrations of untreated ethylene glycol in stormwater where ethylene glycol is the primary deicing compound used:
Ethylene glycol concentration = 2.1 * BOD5 concentration (1)
Ethylene glycol concentration = 0.78 * COD concentration
Ethylene glycol concentration = 2.6 * TOC concentration

(1) BOD5 correlation uses ethylene glycol analysis data from Corsi, S.R., Mericas, D., and Bowman, G.T., 2012, Oxygen Demand of Aircraft and Airfield Pavement Deicers and Alternative Freezing Point Depressants: WATER AIR AND SOIL POLLUTION, v. 223, no. 5, p. 2451.

fieldMethods:
Test kits for ethylene glycol and propylene glycol in water were developed for use in boiler feed applications. Because ethylene glycol test kits were developed for specific concentration ranges and water matrices that have little other interference, the accuracy of this method for general storm water analysis is unknown. Test kits that measure glycols by colorimetric methods may be useful as presence/absence indication in the field. Field monitoring devices based on refractive properties of the monitored liquid can be used to measure glycols, although accuracies are limited to approximately 1% or 10,000 mg/l.


formsAndSources:
Total organic carbon (TOC) is a measure of organic (i.e. carbon based) materials in water, including anthropogenic organic compounds. Organic materials may be present as particulate matter or as dissolved organic carbon (DOC). Sources of TOC include natural organic matter in plants and animals as well as synthetic organics such as fuels, solvents and paints. Engine oils, hydraulic fluids, transmission oil, deicing compounds, radiator fluids, paint chips and jet fuel may all be sources of organic carbon generated from airport activities.

enviroEffects:
High concentrations of organic carbon in the environment may cause a high demand on oxygen in receiving waters as degradation of natural organic materials requires oxygen. Some synthetic organics do not biodegrade quickly or at all and may be environmental toxins that bioaccumulate in aquatic life.

monitoringChallenges:
Online monitoring methods can be expensive and require maintenance and calibration. However, the online methods provide the most representative monitoring results because they capture the full range of monitored conditions.

relatedParameters:
Total organic carbon (TOC) is often used as surrogate parameters to indicate concentration of glycols in stormwater. Glycols are biodegradable and oxygen in the water is consumed as a part of the degradation process. Where one constituent such as propylene glycol is the primary biodegradable constituent, strong correlations between TOC and the concentration of COD and the organic compound exist. Correlations between TOC, COD and BOD are less accurate for samples containing a mixture of glycols, acetates, formates, or other constituents. Acetates, formates, or other non-glycol organics can be present either through direct application in pavement deicers or through partial degradation of glycols. These correlations are discussed in more detail in the “Glycols” fact sheet.

Correlations between organic carbon and glycol concentrations are most accurate when concentrations of glycols are high and when samples are dominated by a one primary biodegradable constituent. At lower concentrations of glycols or when a mixture of organic compounds is present, correlations may not be accurate or site-specific testing may be required.

fieldMethods:
TOC is often measured at airports using online monitoring devices that oxidize carbon by using thermal oxidation, UV light or UV/ozone oxidation. Each TOC method requires sample filtering because the monitors will not handle solids. 

Handheld or online refractometers may also be used to measure TOC when glycol concentrations are high (i.e. greater than 1 percent or 10,000 mg/L). These methods are calibrated to glycol and are variable when glycol is not the majority of the TOC.


formsAndSources:
Major sources of dissolved oxygen (DO) in water are the atmosphere and photosynthesis by aquatic vegetation. Air contains approximately 20.9% oxygen gas by volume. The amount of oxygen available for aquatic life depends on the factors that affect the solubility of oxygen in water. The proportion of oxygen in air that dissolves in water is about 35%. This solubility of oxygen in water depends on atmospheric and hydrostatic pressure, turbulence, temperature, salinity, currents, upwellings, ice cover, and biological processes occurring.

The DO concentration in water is largely controlled by the balance between the input of oxygen and the degradation of oxidizable matter. Anthropogenic influences may result in the discharge of organic compounds to receiving waters, which consume oxygen as they degrade and subsequently lower the dissolved oxygen concentration in water. 

Biochemical oxygen demand (BOD) measures how much oxygen microorganisms consume during decomposition of organic materials and certain inorganic matter. Chemical oxygen demand (COD) is a measure of the amount of oxygen required for chemical oxidation of inorganic and organic materials. Higher BOD and COD (i.e. higher oxygen consumption) results in lower DO. Sources of BOD/COD include dead plants and animals as well as biodegradable anthropogenic chemicals (e.g., propylene glycol). If both BOD and COD are measured, the COD value should be larger than the BOD value.

enviroEffects:
Reduced DO concentrations (and corresponding elevated BOD/COD) have been shown to cause lethal and sublethal (physiological and behavioral) effects in various organisms, especially fish. Decreased DO concentrations can modify the susceptibility of aquatic organisms to environmental stresses such as the presence of toxic substances.

If prolonged changes in DO occur, modifications can also be expected in the local biotic community structure (e.g., benthic communities). Species intolerant of depressed DO will either die or try to avoid such environments, while the more tolerant species, originating from either within the habitat or colonized from elsewhere, will survive.

monitoringChallenges:
Although laboratory methods may be used, it is recommended to measure DO in the field in situ, and not from a sample container. The sample should not remain in contact with air or be agitated because either condition can affect the DO concentration. If collecting a sample for laboratory analysis, avoid entraining or dissolving atmospheric oxygen, which may be performed by letting the sample bottle (use a narrow-mouth glass-stoppered BOD bottle) overflow two or three times its volume and replacing the stopper so that no air bubbles are entrained. At time of sampling, the sample temperature should be recorded as precisely as required. Another reason for favoring field analysis over laboratory analysis is that samples must be analyzed as soon as possible. Samples having an appreciable iodine demand or containing ferrous iron must be preserved and analyzed within 4-8 hours of sample collection.

Online monitoring methods can be expensive and require maintenance and calibration. Test kits and handheld meters are less precise and may require frequent calibration and frequent replenishment of consumables.

relatedParameters:
Biochemical oxygen demand (BOD) and chemical oxygen demand (COD) are often used as surrogate parameters to indicate concentration of glycols in stormwater. Glycols and other compounds in deicers are biodegradable and oxygen in the water is consumed as a part of the degradation process. These correlations are discussed in more detail in the “Glycols” fact sheet.

A surrogate parameter for BOD is total organic carbon (TOC). The TOC analytical method converts all of the organic carbon in a sample to carbon dioxide and measures the amount of carbon dioxide produced. Because the conversion of organic compounds to carbon dioxide is essentially complete in a TOC analysis, TOC represents a more conservative representation of the potential oxygen demand. TOC correlates well with the concentration of organic compounds and to COD in water samples dominated by a single constituent (e.g., propylene glycol). In samples that contain a mixture of constituents, such as glycols, acetates, and formates, the correlations among TOC, COD, and BOD become less accurate.

fieldMethods:
Field monitoring for oxygen demand may be conducted using handheld meters, field test kits or online monitors. Handheld meters and online DO monitors use either the amperometric method or the optical method. Optical sensors are generally favored over amperometric meters as they are more robust in the field. Field test kits using the Winkler method measure DO content using a reagent reaction followed by titration. Accuracy and precision vary based on the titration method used. 

Online BOD monitors may be installed that function by measuring DO before and after sample water has passed through a vessel containing bacteria which degrades deicer and consumes DO in the process. The decrease in DO can be correlated to BOD concentration. The differences in contact time and temperature between the BOD laboratory method and online method may lead to different biological conditions and measurement responses. Therefore, online BOD should be considered a correlation to laboratory BOD concentrations, similarly to COD or TOC. Due to the differences in test conditions, when using the online BOD instruments, it is important to field test the instrument output in response to samples with various combinations of expected constituents at known concentrations and compare the results to laboratory BOD test results.

COD may be measured by test kits using the photochemical oxidation method and the dichromate method. Online methods for COD measurement include the photochemical oxidation method and the electrochemical oxidation method.
 
Handheld or online refractometers may also be used to measure BOD/COD when glycol concentrations are high (i.e. greater than 1 percent or 10,000 mg/L).

Footnotes:
a) The water column concentrations are recommended to achieve the required intergravel dissolved oxygen concentrations. For species that have early life stages exposed directly to the water column, the intergravel concentrations apply;				
b) Includes all embryonic and larval stages and all juvenile forms to 30-days following hatching;	
c) For reservoir or other manipulable discharges, the application of the one day minimum criterion must limit either the frequency of occurrence of values below the acceptable 7-day mean minimum or must impose further limits on the extent of excursions below the 7-day mean minimum.  For such controlled discharges, it is recommended that the occurrence of the daily minima below the acceptable 7-day mean minimum be limited to 3 weeks per year or that the acceptable one-day minimum be increased to 4.0 mg/L for coldwater fish and 3.5 mg/L for warmwater fish.


formsAndSources:
Total dissolved solids (TDS) include all of the dissolved solids in water including both organic material and inorganic minerals in ionic form (e.g., Na⁺, Ca²⁺, Cl⁻, Mg²⁺, NO₃⁻, HCO₃⁻). TDS is defined as the filterable residue remaining in a water sample that has been passed through a 0.45 micron filter and dried at specified temperature (typically 180°C). The weathering and dissolution of rock or soil, and the decay of organisms, plants, animals, and waste products all contribute to natural sources of TDS in runoff and surface waters. Man-made sources of TDS include agricultural and residential runoff, road salts, point source water pollution, and industrial and sewage discharges. At airports, significant concentrations of TDS in stormwater can be associated with the application of pavement deicers, both airside and landside.

enviroEffects:
Fluctuations in aqueous TDS concentrations may cause adverse effects to the cells of aquatic organisms. Cells in  water with very low concentrations of dissolved solids may swell and potentially burst as water moves into the cell. Conversely, cells may shrink or desiccate in waters with high concentrations of TDS as water within the cell moves out. Since TDS is composed of a variety of dissolved components, it is used primarily as an aggregate indicator of pollutants including pesticides, salts, nutrients, minerals, and dissolved organic material. TDS also includes minerals such as Ca²⁺ and Mg²⁺ that contribute to elevated hardness. 

High concentrations of TDS in potable water contribute to aesthetic issues such as bad taste and may have agricultural limitations for irrigation of salt-sensitive crops. The presence of TDS at concentrations higher than regulatory limits is challenging because it is extremely difficult and costly to treat TDS in stormwater.

relatedParameters:
In addition to electrical conductivity, TDS is related to salinity. Salinity is a measure of the amount of dissolved salts in water and therefore is a fraction of TDS. In freshwater, TDS and salinity are approximately equal, but in stormwater and wastewater TDS can include organic solutes such as hydrocarbons and urea in addition to salt ions.

fieldMethods:
Strong correlations between electrical conductivity and TDS can be established. Therefore, a field electrical conductivity meter can be used to indirectly measure TDS.  Generally, conductivity (in micromhos per centimeter or microsiemens) may be multiplied by an empirical factor to estimate the TDS concentration. The empirical factor may vary from 0.55 to 0.9 depending on the constituents that make up TDS and on the temperature of the measurement.


formsAndSources:
Total suspended solids (TSS) include natural or introduced fine particles suspended in water that are retained by a filter (also called filterable solids). Particles passing through the filter are called total dissolved solids (TDS). Collectively, TSS and TDS make up Total Solids.  TSS includes silt, clay, plankton, algae and fine particles of organic and inorganic matter. TSS does not include gross solids such as sand and gravel, trash and large debris. TSS is typically measured by weighing the solids retained by a 0.45 to 2.0 micron filter, which has been dried at a specific temperature (usually 103°C -105°C).

Fine particles are ubiquitous in urban runoff.  Natural sources of TSS are abundant and include weathering and dissolution of rock or soil (i.e., erosion and scour), and the decay of organisms, plants, animals, and waste products.  These sources are typically terrestrial but may also be atmospheric.  Anthropogenic sources include both diffuse sources such as agricultural and residential runoff and point sources such as end of pipe discharges (e.g. industrial, sewage or pollution) and smokestack emissions. At airports, sources of suspended solids may include airborne dust and pollen, erosion from pervious areas (e.g., infields, landscaped areas, etc.), leaf litter, traction sands, and washwater from aircraft, ground vehicle and equipment washing. Biofilms that may be collected in the sampling process, as well as biological treatment plant bacteria will also register as TSS.

enviroEffects:
Fine particles can cause impairments to receiving waters by causing turbidity and siltation. Fine particles can be toxic to aquatic life, in particular inhibiting gill functioning and reproductive activities in fish. Additionally, fine solids have a high specific surface area, which provides opportunity for other pollutants of concern such as pathogens, metals and pesticides to be adsorbed. TSS of a biological nature can degrade in streams and storm sewers over long periods, resulting in an uptake of dissolved oxygen.

monitoringChallenges:
The nominal filter pore size used by the laboratory may vary, which can affect TSS results. In stormwater sampling, error can be introduced through differences in mixing speeds and methods, subsample locations, and equipment. These primarily influence the amount of larger, heavier particles that are captured in a sample.

relatedParameters:
Turbidity may be used as an indication of the amount of colloidal or suspended particles in water. Turbidity measures the quantity of light scattered or reflected by particles in water and is a function of the size distribution of the particles. Developing a correlation between TSS and turbidity may be challenging because the size, shape, and refractive index of the particles affect the light-scattering properties of the suspension. The correlation developed is unique to each monitoring location.

fieldMethods:
No effective field methods are available for TSS, but field methods are available for parameters that could be used as surrogates for TSS, such as turbidity and volumetric particle size distribution (e.g., Laser In-Situ Scattering and Transmissometry). There are a number of manufacturers of field turbidity meters. The USGS National Field Manual for the Collection of Water-Quality Data, TWRI Book 9 includes a chapter detected to field turbidity measurement.


formsAndSources:
BTEX consists of benzene, toluene, ethylbenzene, and xylenes (including ortho-Xylene, meta-Xylene, and para-Xylene), which are volatile monocyclic aromatic compounds that are highly soluble.  BTEX compounds are frequently found in or near natural and processed petroleum products, as well as household and other goods such as rubber, plastic, nylon, insecticides, paints and solvents, and cigarettes. Due to their volatility, BTEX compounds tend to volatize on contact with the atmosphere.  While BTEX compounds have been studied extensively in groundwater, there is limited information regarding BTEX prevalence, characteristics, and concentrations in surface water and stormwater. 

BTEX compounds are typically released to the environment during production, transportation, use, storage or spills of petroleum products and through emissions from motor vehicles and aircraft. BTEX can accumulate in groundwater near crude oil, coal and gas deposits and production facilities.  BTEX compounds can also be released during use of household products containing petroleum-derived components. At airports, ground vehicle, and equipment servicing/maintenance, fueling, and washing, and runway maintenance are sources of BTEX where gasoline is present.

enviroEffects:
There is limited information regarding the toxicity of these compounds on aquatic life; controlled testing is challenging to carry out due to the volatility of the compounds.  All BTEX compounds are toxic to aquatic life at threshold concentrations, with mortality occurring at high enough concentrations.

Benzene and toluene toxicity tests on freshwater and saltwater species have demonstrated developmental and growth effects.

monitoringChallenges:
Because of their volatility, BTEX compounds must be collected as grab samples and cannot be collected as composite samples.
Glass containers must be used for sample storage.

relatedParameters:
BTEX are components measured as part of the TPH-gasoline analysis.


formsAndSources:
Cadmium (Cd) is a naturally occurring metal that is typically found in the environment as complex oxides, sulfides, and carbonates in zinc, lead, and copper ores. Cadmium is typically found in the (+II) valence state. Cadmium forms several complexes with anions: halides, nitrate, sulfate, thiosulfate, ammonia, and cyanide. Complexes with organics (CdDOM) and also ionic cadmium (Cd²+) are predominant in urban runoff. A large number of salts and basic salts of cadmium are sparingly soluble or very sparingly soluble, i.e., hydroxide, carbonate, phosphate, and sulfide.  The solubility and partitioning of cadmium depends on a number of factors including pH, cations present, organic carbon present, and adsorbing surfaces. In the environment, cadmium partitions mostly to soil with sorption generally increasing with pH and the presence of organic materials.  Cadmium is more mobile in aquatic environments than most other heavy metals, existing in dissolved state as a  hydrated ion. However, in sediment or organic-rich waters, particulate cadmium concentrations may be a significant portion of the total cadmium present.  

Cadmium is commonly used in batteries, a variety of alloys, and electroplating, as well as pigments, plastics, and other synthetics. Cadmium is emitted to the environment by mining, refining, zinc production, fossil fuel combustion, and waste incineration and disposal activities, via application of phosphate fertilizers, and also via plated components of automobile brake components and aircraft parts.  Additionally, cadmium plating is often used to treat surfaces of aircraft steel parts, including airframe components and fasteners, as a means of corrosion prevention.  However, cadmium corrosion from these parts can occur as a result of application of pavement deicing products. At airports, fuel spills and runoff from fueling areas, and spent washwater from aircraft, ground vehicle, equipment washing are sources of metals in general.

enviroEffects:
Immobilized cadmium that has sorbed to soil can be taken up and retained by aquatic and terrestrial plants, and these pathways as well as soluble forms can lead to bioaccumulation in aquatic and terrestrial organisms.  Cadmium does not break down in the environment, though it may change forms. Toxicity of cadmium is increased in the presence of metals such as copper and zinc, both of which may be present at elevated concentrations in stormwater. 

Effects of high level cadmium exposure to animals may include kidney, liver, bone, blood, nerve, and brain damage.  Human exposure can occur by eating plants and other organisms in which cadmium has bioaccumulated, and to a lesser extend through inhalation.  Inhalation and ingestion of lower levels of cadmium over many years can result in a build-up of cadmium in the kidneys, resulting in damage.

monitoringChallenges:
As with all metals, there is potential for sample contamination from the surrounding environment. If a high resolution analytical method is used (e.g., EPA 1600 series), EPA recommends using clean sampling protocols (i.e., “Clean Hands, Dirty Hands”) to prevent contamination.
 
Samples must be filtered for dissolved copper within 15 minutes of sample collection. The filtered samples may be preserved in the field or transported to the laboratory for preservation.

Because cadmium can have significantly different concentrations in the water column versus solids, the sample collection point should be well-mixed to account for both phases to get an accurate concentration in the flow stream.

Footnotes:
a) The freshwater criterion is expressed as a function of hardness (mg/L) in the water column. The value given here corresponds to a hardness of 100 mg/L. The criterion for other hardness concentrations may be calculated per the equation CCC=exp(0.7409[ln(hardness)]-4.719)*CF, where CF= 1.101672-[(ln(hardness)*0.041838].


formsAndSources:
Chlorine and chlorine-related compounds (other than chloride) are often present in waters as a result of disinfection at water and wastewater plants.  Hypochlorite and hypochlorus acid are produced when elemental chlorine (Cl₂, which is typically unstable in aqueous solution) reacts with water, forming what is commonly referred to as “free chlorine”. These compounds further react with nitrogen in the form of ammonia and organic compounds to create chloramines (“combined chlorine”).  Free chlorine and combined chlorine are referred to as “total residual chlorine” in water.  Total residual compounds can react with organic compounds to create organo-chlorinated compounds, or can change water chemistry to result in production of chlorine-produced oxidants, typically brominated compounds. 

Chloride is the ionic form typically present in water and soil as part of a salt complex (e.g. NaCl) or as a dissolved chloride anion (Cl-).  It is highly soluble and mobile, and in both forms, chloride can exchange and bond with other cations such as calcium, magnesium, potassium, hydrogen, and aluminum, resulting in leaching of these constituents from soil.  

Chlorine can enter the environment through chlorine residuals from potable water sources (e.g. drinking, bathing, irrigation sprinkers, etc.), chlorinated water in swimming pools, wastewater treatment plants, and from industrial dischargers that use chlorine in manufacturing of plastics, cleaning products, insecticides, and other chemical compounds. Chloride can enter the environment from deicing salts, municipal wastewater plants, industrial plants that produce or use salts, caustic sodas and other compounds, oil and gas well drilling, and areas of salt-water intrusion. At airports, chloride salt deicers are not used in aircraft movement areas because they cause corrosion (therefore airport deicers are typically a mixture of glycols). Some airports use chloride salts on roads and parking lots.

enviroEffects:
Total residual chlorine compounds are considerably toxic to aquatic life.  Chlorine compounds can result in toxic and lethal affects to aquatic organisms, including tissue and developmental effects.
 
Elevated concentrations of chloride can occur in areas where road salts are applied during the winter months.  These concentrations can result in acute toxicity to aquatic animals by affecting cell osmotic function, reducing population density.

monitoringChallenges:
There are monitoring challenges related to chlorine due to its reactivity and volatility.  As a result of these characteristics, EPA recommends that it is analyzed immediately (i.e. within 15 minutes of collection).

fieldMethods:
Free chlorine residual may be measured in the field using simple color changing kits that are commonly used for testing swimming pools. These kits do not provide reliable quantitative results. Quantitative measurements of total and free chlorine may be collected using a digital colorimeter.


formsAndSources:
Copper is a naturally occurring element in rocks and soil, from where it can be dispersed to air, water, plants, and animals through both natural and human-influenced processes. Copper may exist as a dissolved or particulate-bound pollutant in stormwater and surface water bodies.  Copper may be present in water in a dissolved ionic form as Cu²⁺ and infrequently as Cu+. Copper complexes with five key chemical groups: organics (CuDOM), carbonate (CuCO₃), hydroxide (CuOH+), sulfates (CuSO₄), and chlorides (CuCl). Of these, complexes with organics (CuDOM) and carbonate (CuCO₃) are predominant in stormwater. CuCl can also become significant in coastal areas and areas subject to road de-icing salts containing chlorides.

Mining, leather and leather products, fabricated metal products, and electric equipment are a few of the industries with copper-bearing discharges that contribute to anthropogenic discharges of copper into surface waters. Copper is released from natural sources such as volcanoes, windblown dusts, decaying vegetation, and forest fires.  Diffuse sources of copper include agricultural and commercial applications, gardening applications, leaching from paint on vessels and infrastructure. Automobile brakes generate abraded copper metal or alloyed copper during their normal use, contributing to copper in dry or wet deposition.  

Additionally, environmental releases can occur from consumer products containing copper, including coins, cigarettes, jewelry, electrical appliances, cookware, unwashed agricultural products, commercial gardening products, vitamin/ mineral dietary supplements, and treated wood products. At airports, brake dust from aircraft and vehicles, fuel spills and runoff from fueling areas, and spent washwater from equipment maintenance are potential sources of copper.

enviroEffects:
Copper can be toxic to aquatic and benthic organisms at relatively low concentrations.  Freshwater fish, and salmonids in particular, are very sensitive to copper. Exposure to dissolved copper has been shown to cause olfactory impairment in fish, resulting in an impaired avoidance response to predators. However, toxicity is primarily a function of bioavailability, which may be reduced with increased pH, hardness, and dissolved organic carbon concentration.

monitoringChallenges:
As with all metals, there is potential for sample contamination from the surrounding environment. If a high resolution analytical method is used (e.g.., EPA 1600 series), EPA recommends using clean sampling protocols (i.e., “Clean Hands, Dirty Hands”) to prevent contamination.
 
Samples must be filtered for dissolved copper within 15 minutes of sample collection. The filtered samples may be preserved in the field or transported to the laboratory for preservation.

Because copper can have significantly different concentrations in the water column versus solids, the sample collection point should be well-mixed to account for both phases to get an accurate concentration in the flow stream.

Footnotes:
a) Aquatic life freshwater quality criteria are calculated using the Biotic Ligand Model, a metal bioavailability model.


formsAndSources:
Nitrogen exists in the environment in various chemical forms. The nitrogen cycle refers to the complex process where nitrogen is converted between these various forms, or oxidation levels. Nitrogen can exist as organic or inorganic matter, as reduced nitrogen (ammonia with an oxidation state of -III), as oxidized nitrogen (nitrite with an oxidation state of +III or nitrate with an oxidation state of +V) or as nitrogen gas (with an oxidation state of 0). The various operations and processes for treatment of nitrogen species and phases are essentially conversions from one form and oxidation state, or one phase of nitrogen, to another. 

Common nitrogen species are: 
Ammonia gas (NH₃), Ammonium ion (NH₄⁺), the intermediate species of nitrite (NO₂⁻¹), the mobile species of nitrate (NO₃⁻¹), Nitrogen gas (N₂).

The dominant forms of nitrogen in stormwater runoff are: 
Organic Nitrogen, Nitrate (NO₃), and Ammonia (NH₃).

Nitrogen concentrations are typically reported using the following indices:
Total ammonia nitrogen = (NH₃ + NH₄⁺)aq, Total inorganic nitrogen = (NH₃ + NH₄+ NO₂⁻¹ + NO₃⁻¹)aq, Total Kjedahl nitrogen (TKN) = Organic N + NH₃ + NH₄⁺, Organic nitrogen = TKN – (NH₃ + NH₄⁺), Total nitrogen = TKN + NO₂⁻¹ + NO₃⁻¹.
 
Organic nitrogen is typically derived from soil, plant and animal material associated with agricultural land uses. Nitrogen also originates from land uses where fertilizers are applied, vehicle exhaust, and food products, most of which contain nitrogen in various organic and inorganic forms. Urea has been used historically as a pavement deicer and degrades to ammonia in the environment. Also, ammonia may be present in biological deicer treatment system discharges where nitrogen-based compounds are added as a nutrient.

enviroEffects:
The primary environmental concerns with nitrogen in stormwater are eutrophication and toxicity.  Nitrate is readily available for biological uptake and, when present with sufficient amounts of phosphorus, can cause eutrophication and undesirable effects such as algal blooms in waterbodies. Ammonia is of concern due to its fairly rapid transformation to nitrate, but also because it can be toxic to some aquatic species at fairly low concentrations.

monitoringChallenges:
The laboratory analysis holding time for nitrate and nitrite (quantified as individual species) is 48 hours.
A variety of real-time instruments have the capability of monitoriing for ammonia. Results from these instruments (as well as from test kits) should be compared using split samples against EPA laboratory methods. Concentrations of ammonia-nitrogen less than 1 mg/l may be especially susceptible to variability among instruments and methods.

fieldMethods:
Nitrate may be measured in the field by mixing a water sample with a mild acid and a nitrate reducing agent (typically zinc or cadmium).  Nitrate is reduced to nitrite and then the resulting nitrite concentration is determined using a color comparator or a field colorimeter. Field test kits and colorimeters are available from several manufacturers.


# tblTempReport

formsAndSources:
In the environment, phosphorus typically occurs as part of a phosphate molecule (PO43-), which can be a free molecule (orthophosphate), part of inorganic molecules, or part of numerous organic molecules. Because of the many forms, phosphorus is usually reported as orthophosphate, dissolved phosphorus, or total phosphorus. Elevated concentrations of phosphorus can occur through weathering of certain minerals, but mostly occur through anthropogenic inputs such as wastewater effluent, septic system seeps, and animal manure. Phosphorus compounds are typically added, along with other nutrients, to crops as fertilizer. Phosphorus may also be present in flame retardants, corrosion inhibitors, and plasticizers. Phosphorus compounds are also added as a nutrient necessary for bacterial growth in biological deicer treatment systems.  Both inorganic and organic phosphorus can be dissolved or associated with particulate organic matter.

environmentalEffects:
In many surface waters, phosphorus is the limiting nutrient, so small increases in phosphorus can cause substantially accelerated growth of plants and algae. Algae blooms can cause decreased dissolved oxygen concentrations which can smother other aquatic life, and dead algae cells can alter streambed characteristics, impacting habitat for fish and other aquatic life. Because it is an element, phosphorus cannot be destroyed, but it is part of many transformation reactions that are naturally occurring. Plants can only uptake inorganic phosphorus, which becomes part of their biomass. Animals get phosphorus by ingesting plants and other animals. As organisms excrete waste or die, organic phosphorus is released back to the environment, where microbes break it down to inorganic phosphate, completing the cycle.


# userSettings

comments:
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