Are Volatile Aromatic Compounds
Present in the Downtown
Oklahoma City Watershed?
A Fourth Year Study of
Oklahoma City Water Quality

Andria Parker
Classen School of Advanced Studies
Oklahoma City, Oklahoma 73106

ABSTRACT

The purpose of this project is to test for volatile aromatic compounds in the downtown Oklahoma City watershed. A series of other tests (pH, dissolved oxygen, phosphate phosphorous, nitrate nitrogen, and ammonia nitrogen) were performed at each site as well to further determine the water quality of the watershed. The tests for volatile aromatic compounds were conducted in a laboratory using a gas chromatograph spectrometer, while the second series of tests were performed on site. No levels of the volatile aromatic compounds were detected from site samplings, while intennediate levels (according to state water quality standards) of other pollutants were detected in the majority of the second series of tests. Although no volatile aromatic compounds were detected in the watershed, the intermediate levels of pH, dissolved oxygen, phosphate phosphorous, nitrate nitrogen, and ammonia nitrogen suggest that the water quality of the downtown watershed is also at an intermediate level.

The results of this project are important to residents and landowners near the downtown Oklahoma City watershed. The. absence of these potential carcinogens also affects other Oklahoma City residents because of the Metropolitan Area Projects (MAPS) which will greatly increase the public use of the area. This plan incorporates water into several elements of its design. In particular, the River Front Corridor Plan calls for a river-lake that will impound the watershed evaluated in this research project. Now, more than ever, good water quality is an integral part of the development and stability of cities, large and small.

Introduction

This research project is the fourth phase of a study of the water quality of Oklahoma City. The Arst phase analyzed the water quality of the North Canadian River Basin in Oklahoma City by testing the pH, dissolved oxygen, phosphate phosphorous, nitrate nitrogen, and ammonia nitrogen levels in the waterways. The water quality of the basin was found to be at an intermediate level, The second phase analyzed the water quality of the Arcadia Watershed and determined the effectiveness of using macroninvertebrate populations as biological indicators of water quality. This study found the water quality of the watershed to be good and the macroinvertebrates to be accurate biological indicators of water quality. The third phase analyzed the impact that urbanization has on waterways by testing for pH, dissolved oxygen, phosphate phosphorous, nitrate nitrogen, and ammonia nitrogen, collecting samples of macroinvertebrate populations, and characterizing the physical appearance of each of 35 sites. This phase found that the impacts of urbanization can be seen in their effects on water quality, quantity and diversity within a macroinvertebrate population, and the physical nature of a waterway.

This fourth phase was designed to analyze another aspect of water quality in Oklahoma City. With the forefront of the Metropolitan Area Projects (MAPS) in downtown Oklahoma City and the incorporation of the River Front Corridor Plan in downtown, I felt that it was important to know the area's water quality. I chose to test for petroleum derivatives, specifically volatile aromatic compounds and benzene derivatives, in the downtown Oklahoma City Watershed. I presented my past research and my plans for the fourth phase to the Isotek L.L.C. Laboratory Services which agreed to financially sponsor my research of the fourth phase.

I chose to test for volatile aromatic compounds for several reasons.1) Petroleum constituents and benzene and its derivatives are extremely carcinogenic. (Hart, Hart and Craine, 1995) 2) In Oklahoma benzene is the only pollutant in a waterway that by law requires an immediate implementation of the cleanup of the waterway. (County Commission Offices, 1997)3) Petroleum is one of Oklahoma's most abundant natural resources and could pose a potential threat to the land and water quality. (County Commission Offices, 1997) I chose to test for the presence of benzene, toluene, ethylbenzene, xylenes, naphthalene and total petroleum hydrocarbons.

In addition to testing for the presence of volatile aromatic compounds, I also assessed the water quality of the watershed by testing for pH, dissolved oxygen, phosphate phosphorous, nitrate nitrogen, and ammonia nitrogen levels.

Research

Water is life. Our entire existence depends on water. We can live without food for a month but without water for only seven days. Two thirds of the earth's surface is covered in water. Of this, 97% is saltwater. Two of the remaining three percent is frozen at the north and south poles. Half of the remaining. 0.5% is our freshwater supply. This water, fresh and unfrozen, is found in lakes, rivers, ponds, and streams. Obviously. It is very important for us to keep the water clean whether it is in a lake, river, pond, or stream. (National Geographic, 1993) (Cobb, 1986)

In tributaries, there are different types of environments and habitats. In most tributaries, there are riffles, pools, and runs. A riffle has a surface which is definitely broken and ususUV makes a sound. A pool has a smooth surface, no or little current, and can be deep or shallow. A run has an obvious current, may be deep or shallow, and often has a surface which may be slightly broken, but does not make any noise. If a stream has no water in it, then it is called a dry stream. Substrate is the type of material found at the bottom of a stream. The different types of substrates are loose silt and clay, gravel, cobble, boulder, bedrock or hardpan clay, and particulate organic matter (rotten leaves and fragments of sticks and logs). (Kolbe and Luedke, 1993)

This project tests for levels of volatile aromatic compounds. A compound is formed when different elements combine to form a molecule. A molecule is the smallest part of a substance that has the chemical properties of the substance. An example of a compound is water, H2O. Two atoms of hydrogen join one atom of oxygen to form the compound, water. Other tests in this project are for volatile total petroleum hydrocarbons (TPH). Hydrocarbons are organic compounds and include thousands of compounds that contain only hydrogen and carbon. There are different groups of hydrocarbons called series, such as the methane series, the ethylene series, and the acetylene series. Hydrocarbons are derived from petroleum. Substances that result from the reaction of hydrocarbons with other compounds are called hydrocarbon derivatives; These include alcohols, aldehydes, and acids. Aromatic compounds were among the first natural products studied by chemists and are based on the unsaturated, six carbon ring of benzene with one or more hydrogen atoms replaced by alkyl or other functional side groups. Aromatic compounds, in comparison with other hydrocarbons, have a higher solvency and stronger odor They have simple structures like those of benzene, benzaldehyde, benzyl alcohol, and toluene. Aromaticity, the unusual stability of certain fully conjugated cyclic systems, is evident in other compounds. For example, naphthalene, C10H10, was the first pure compound to be obtained from the higher boiling fractions of coal tar. These polycyclic aromatic hydrocarbons are carcinogenic, In lab tests, mice have developed tumors quickly when exposed to traces of the compounds. These carcinogenic hydrocarbons are formed in coal tar, tobacco smoke, and barbecuing. The body usually oxidizes them so they are more soluble in water in order for excretion. (Hart, Hart, and Craine, 1995)

The second series of tests conducted in this experiment tests for levels of dissolved oxygen, pH, phosphate phosphorus, nitrate nitrogen, and ammonia nitrogen. The air and water temperatures were also taken.

Dissolved oxygen is one of the most important tests of water quality for aquatic life. If the dissolved oxygen levels fall below 3-5 mg/L, organisms may have difficulty reproducing, feeding or surviving. Oxygen is added to the water by an aerating action of the wind and waves through diffusion or physical aeration. Oxygen can also be added by the process of photosynthesis. The oxygen producing process generally occurs at the surface of the water because of the availability of light In this area. The presence of oxygen may be reduced if the water is too warm by reducing its solubility or if there are too many bacteria or other organisms such as algae. The process by which these organisms reduce the amount of oxygen is called respiration. Overabundant organisms can consume most of the dissolved oxygen In their efforts to survive. The test used determines precisely the amount of oxygen that is dissolved in water. The amount of oxygen that water can hold decreases as the temperature and salinity of the water increases. The barometric pressure also determines the capacity of oxygen that water has. When water holds all of the dissolved oxygen that it can at a given temperature, it is 100% saturated with oxygen. If water holds half as much dissolved oxygen as it can hold at a given temperature, it is 50% saturated with oxygen. The algae that consumes oxygen may be due to run-off from over fertilized farmland, urban runoff, golf course nrnoff, or sewage effluent which contains high levels of phosphorous and nitrogen. This algae can consume so much oxygen that "fish-kills" can occur. (Cobb, 1986)

Figure 1 Relationship Between Solubillty of Oxygen
in Water and Water Temperature

Temp.
°C		Solubility
(mg/L)		Temp.
°C		Solubility
(mg/L)		Temp.
°C		Solubility
(mg/L)
014.61111.1219.0
114.21210.9228.9
213.81310.6238.7
313.51410.4248.6
413.11510.2258.4
512.81610.0268.3
612.5179.8278.1
712.2189.6287.9
811.9199.4297.8
911.6209.2307.7
1011.3



pH is a measure of how acidic or basic a solution is. In solution, some molecules break apart to form hydrogen ions (H+) and hydroxyl ions (OH-). The pH scale is a means of showing which ion has the greater concentration. At a pH of 7.0, the concentration of both ions is equal and the solution is said to be neutral. When the pH of water is less than 7.0 there are more hydrogen ions than hydroxyl ions. When the pH is greater than 7.0 there are more hydroxyl ions than hydrogen ions. The pH does not increase or decrease in a linear fashion because it is calculated as the negative logarithm of the hydrogen ion concentration. For example, a pH of 3 is not twice as acidic as a pH of 6. Increases are in powers of 10. At a pH of 5, there are 10 times more H+ ions than at a pH of 6. Therefore, a change in pH of 1 whole number Is very significant and can have a great impact on the water quality of the area being sampled. The ability of water to buffer acidic waters is measured by its alkalinity. Generally, an aquatic organism's ability to complete a life cycle greatly diminishes as the pH becomes greater than 9.0 or less than 5.0. There are several factors that can affect the pH of water. Dissolved mineral substances, aerosols or dust from the air, and man-generated wastes which are discharged or illegally dumped into a lake or stream can affect the pH of water. (Owen and Cauthorn, 1994)

Phosphate phosphorous is present in water in many forms including organically bound phosphorous, inorganic polyphosphates and inorganic orthophosphates. Phosphorous occurs in nature almost solely as phosphates. Orthophosphates (P04-3). in particular. occur as ions of phosphoric acid. All inorganic phosphates are generally considered as P04-3. Phosphorus can be introduced from a variety of sources. Phosphates are used extensively in cleaning and laundrv supplies and are present in fertilizers which can be transported to a water body through storm water runoff. Organic phosphates are formed mostly by biological processes, however, domestic sewage can also be a source of these compounds. Phosphorus is a biological active element and therefore cycles through many states. Phosphorus can be removed from the water by chemical precipitation to the sediments or by adsorption to clay particulates which are deposited as sediments. Phosphates are essential to the growth of aquatic organisms. Liebigs's Law of the Minimum states that the element present in the lowest concentration relative to its demand is the element limiting the process at that time. (Hart, Hart, and Craine, 1995) Phosphorus can be the limiting nutrient to primary productivity. When this is the case, the discharge of raw or treated wastewater, agricultural runoff or certain industrial waste waters may serve to stimulate the growth of aquatic plants (both macro and micro). Total phosphorous concentrations in unpolluted waters are usually less than 0.1 mg/L and orthophosphates are often present at levels less than 0.01 mg/L. (Owen and Cauthorn, 1994)

Nitrate nitrogen is a form of nitrogen which occurs in nature. As nitrate is assimilated by algae it is reduced to ammonia. Nitrate (NO3-) can be introduced into the aquatic environment through a number sources. Some sources are sewage, septic waste, and through the transport of nitrogen-based fertilizers. Nitrate may also be introduced into water through atmospheric deposition. Both nitrate and nitrite (NO2-) generally occur in natural waters at very low concentrations with nitrate being the most and frequently less than 1 mg/L during periods of high algal productivity. Nitrates may be found in high concentrations in groundwater. As nitrates are reduced they become nitrites. Nitrites are not present at high levels in natural conditions, but are an essential nutrient for the survival of aquatic micro and macro organisms. (Owen and Cauthorn, 1994)

Ammonia nitrogen (NH4+ ammonia ion and NH3) is a form of nitrate nitrogen in its lowest form. Nitrogen occurs in several different "states" or forms in the aquatic environment. Ammonia is generally produced through the decomposition of organic compounds such as leaf Iltter, woody debris, etc. Ammonia may be introduced into water from various routes. It may enter a lake or stream absorbed to some type of inorganic particle, such as a colloidal clay particle commonly found in Oklahoma, or it may enter through deposition from the atmosphere. Ammonia is available for assimilation by algae and frequently the highest algal growth rates occur through utilization of ammonia, Ammonia is generated In the aquatic system through heterotrophic bacteria as a primary product of the decomposition of organic matter, either directly from proteins or from other nitrogenous compounds. It occurs in water mostly as NH4+. (Owen and Cauthorn. 1994)

There have been many attempts by the government to mandate clean water. The Federal Clean Water Act is one of these. It controls the discharges of pollutants to surface waters in the United States. The requirements prohibit discharges unless they are authorized by specific conditions set forth in federal or state permits. The two classes of permits are: National Pollution Discharge Elimination System (NPDES) permits, which regulate point source discharges that are direct discharges to surface waters, including the oceans, and Indirect discharges to sewage plants; and 2) Dredge and fill permits that regulate point source discharges to navigable waters, including adjacent and isolated wetlands. Municipal governments, companies, and individuals must obtain these permits and also comply with non-permit related requirements. (McCutchen On-Line, 1997) (Stewart, 1993) These types of laws are in effect and are helping to reestablish clean water all over the United States.

Materials and Methods

  1. Designate 11 test sites in the downtown Oklahoma City watershed.
  2. Perform, tests for pH, dissolved oxygen, phosphate phosphorous, nitrate nitrogen, and ammonia nitrogen at selected sites by following the guidelines set forth in the Oklahoma Water Watch Volunteer Monitoring Handbook, and record results on the data sheet for volunteer monitors.
    1. These tests should not be performed six days before or after any precipitation because the levels are calculated in parts per million.
    2. Collect the water of each water sample from the surface water, mid water, and the bottom water near the substrate.
    3. Report these results from to the Oklahoma Water Resources Board.
  3. Collect seventy miililiters ofwater from each site.
    1. These samples should not be collected six days before or after any precipitation because the levels of pollutants are measured in parts per billion.
    2. Collect the water of each water sample from the surface water, mid water, and bottom water close to the substrate. (Although the density of benzene is less than that of water and would most likely be found in the surface water, no bias should be considered when collecting samples. Therefore, collection from all three areas of a waterway is necessary.)
  4. Analyze the seventy milliliter samples using a gas chromatograph spectrometer to detect levels of benzene, toluene, ethylbenzene, total xylenes, naphthalene, and volatile total petroleum hydrocarbons (TPH) .
  5. Compare and analyze data from both testing methods.
  6. Repeat steps 2-5 on all sites.

Discussion

The results of this research suggest that water quality of the downtown Oklahoma City watershed is at an intermediate level because no volatile aromatic compounds were detected and the other levels of contaminants were found at moderate levels. (By "intermediate water quality" it is meant that the levels of pH, dissolved oxygen, phosphate phosphorous, nitrate nitrogen, and ammonia nitrogen were found in moderate levels that meet the water quality standards of the Oklahoma Department of Environmental Quality.) However, the levels of phosphate phosphorous, nitrate nitrogen, and ammonia nitrogen were lower this year than in other years. This might be attributed to the wet season previous to this year's testing. The levels are tested in parts per million and could have been diluted by this earlier precipitation. These levels were found to be lower but there Is the case of site 11. This site is a concrete tributary that drains the runoff from downtown Oklahoma City into the North Canadian River. The levels of contaminants, with the exception of volatile aromatic compounds, were high at this site, although they meet the standards of the Oklahoma DEQ. These high levels could be attributed to the fact that the site carries runoff from downtown, which again would suggest that the water quality of the downtown Oklahoma City watershed is at an intermediate level.

The absence of volatile aromatic compounds suggests that petroleum is being managed well in Oklahoma City. However, the waterways are still being tested for volatile aromatic compounds because of their nature to sometimes fluctuate in a waterway. Levels of pH, dissolved oxygen, phosphate phosphorous, nitrate nitrogen, and ammonia nitrogen are also continuing to be monitored. These results will be compared with past results to see how the weather and season play a role in the different levels of contaminants, because the time frame for testing has, until now, been limited to the fall and winter.

A fifth phase of this research project is being planned. This fifth phase will either determine the effectiveness of entire riparian populations of waterways as biological indicators of water quality or determine the role and effects (if there are any) of socioeconomics on water quality.

Conclusion

When water samples from 11 sites in the downtown Oklahoma City watershed were tested for volatile aromatic compounds that include benzene, toluene, ethylbenzene, total xylenes, naphthalene, volatile total petroleum hydrocarbons TPH), no levels of any compound were detected.

When water samples from 11 sites in the downtown Oklahoma City watershed were tested for levels of pH, dissolved oxygen, phosphate phosphorous, nitrate nitrogen, and ammonia nitrogen, intermediate levels were detected, but did not exceed state water quality standards.

Acknowledgements

I would like to thank the Oklahoma Water Resources Board for their continued cooperation from 1994-1998. In particular, I appreciate the special efforts of Ferrla March. Keith Owen, Bill Cauthorn, Paul Koenig, and Julie Cunningham of that department. Thanks to Rich Davis of the Water and Wastewater Utilities Department, Geographic Information Systems. I thank Marilyn Kelly-St.Clair of the Oklahoma City Sanitation Department, Pollution Control. Thanks also to the North Canadian Sewage Treatment Center. A special thanks to the Isotek L.L.C. Laboratory Services for sponsoring my tests and research for volatile aromatic compounds and Ed Cory of that laboratory for helping me to become familiar with the gas chromatograph spectrometers. Lastly, I thank my parents for their help and support.

References