Nitrate and Phosphate Levels in the Pfeffer Park Stream
Lab Developed by Luke Barber, Adam Beneke, and Brian Breedlove
When people see a creek flowing through a forest, they feel relaxed and think of the beauty of nature. The water in the stream may look and sounds crisp and clean, but if it were tested, it would most likely be unsafe for consumption. Potentially, pollution levels could be so high that a person would have serious problems if they drank the water. Water is an essential substance for all living things, and it is sad to think that humans are the ones who made this water so dangerous. What causes water to become dangerous is the question that our lab is asking.
This area, Oxford, Ohio, and the surrounding region, is highly agricultural, and many of these fields are near streams that flow into the Pfeffer Park creek. Many of the crops in today's fields are far from natural. They are sprayed with countless numbers of chemicals for getting rid of bugs and for fertilization. These chemicals runoff into the streams and pollute the water. This type of pollution is called non-point source pollution (NPS). The EPA gives the following definition for NPS:
Nonpoint source pollution, unlike pollution from industrial and sewage treatment plants, comes from many diffuse sources. NPS pollution is caused by rainfall or snowmelt moving over and through the ground. As the runoff moves, it picks up and carries away natural and human-made pollutants, finally depositing them into lakes, rivers, wetlands, coastal waters, and even our underground sources of drinking water (Cox, 2002).
In this lab, we are going to test the amounts of nitrate and phosphate levels in the Pfeffer Park creek. We are going to compare these results to the level of agricultural activity in the area. We believe that the nitrate and phosphate levels will go down in relation to decreased agricultural activity as time passes, and fields go from active to dormant. Through collecting water samples and running tests we want to provide a direct correlation between the pollutant levels and agricultural activity. With the information we hope to obtain, we would be able to help others who want to reduce NPS pollution, which is the "leading remaining cause of water quality problems" (Cox, 2002).
Each year, farmers cover these fields in chemicals in order to get higher yields and faster growing crops. The human race, as secondary consumers, owes a great deal to the agricultural practices tht promise more food in less space; however, natural habitats in the surrounding areas pay the price.
Farmers spray their crops with an increasingly large amount of fertilizers - phosphates and nitrates. Crops absorb these chemicals and grow faster and stronger. Unfortunately, precipitation causes fertilizers to be washed out of the fields and into the local water system. Eventually, fertilizers pool together and provide a feast for algae. These algae consume all of the fertilizer and reproduce quickly creating an "algal bloom," a great mat of algae produced in a very short amount of time. Soon, there is not enough fertilizer (food) for the algae to survive. The entire bloom dies and sinks to the bottom of the creek or pond. Now, bacteria have a chance to feed. Bacteria decompose the remains of the algae, absorbing dissolved oxygen from the water system. The effect is a lack of oxygen in bodies of water and, thus, the death of marine life dependent upon oxygen (Sarre, 1997). The creek or pond is dead. Another dangerous effect of phosphate and nitrate pollution, and its effects on algal blooms, is the ability of some algae to produce a toxin that is dangerous both to people and animal consumption. A famous and controversial example is the deadly "red tide."
For these reasons, action to reduce the overall amount of fertilizer producing food substances for algae becomes extremely important. If we can study the flux of phosphate and nitrate based NPS pollution, the ability to minimize its harmful effects is increased. The more that we understand the problem, the more possible it becomes to control that problem.
Upon research, several solutions to agricultural runoff seemed viable. In fact, some are currently in practice. In some areas, particularly high fertilizer runoff is reduced by means of a buffer zone, the area surrounding a water system, decreasing runoff, between fields and water systems (Mainstone, 1996). Some research has been put forward that aluminum dust can remove nitrates safely and cheaply from aquifers, where a great amount of nitrates end up (Au-Yeung, 2002; Division of Drinking and Ground Waters, 2000). In the United States and many other industrialized countries, prevention has become a national dilemma, referred to on a large scale as landscape ecotoxicology (Cairns, 1996). For instance, the EPA in the U.S. has control, to a moderate extent, over farming practices in order to control NPS pollution, despite the claim by many farmers that the Environmental Protection Agency has no right to monitor farming practices (Franz, 1999). Other studies have shown that, even despite the "intruding" efforts of the EPA, water pollution is an increasingly dangerous problem. One study graded each state individually just as a student would be graded on a test. Twenty states failed, nineteen received a "D," six received a "C," and the remainder received a "B." No states received an "A" (International Wildlife, 2000). In fact, ninety percent of all Americans reside within ten miles or less of a polluted body of water (Hess, 2000).
Of course, fertilizer pollution is not only a problem for Americans, but the world in general. Seventy-six percent of the world's population live in an area where fertilizers are used even more inefficiently than in industrialized countries such as the U.S. (Sekhon, 1995).
In conclusion, water quality is becoming an increasingly important issue. According to "Freshwater Ecosystems and Their Management: A National Initiative," water consumption has doubled since 1940, and will double again within twenty years (Karr, 1995). These sobering statistics prove our dependence upon clean water, increasing as time passes.
MATERIALS AND METHODS
On Tuesdays, beginning on the first Tuesday after our ordered materials are recieved, and ending on the Tuesday before our results were due, we went to Pfeffer Park creek to collect water samples. Upon surveying the creek, we chose five locations of varying conditions as our constant locations for the weeks in which we will be testing the water and recording data. Our first location was by a broken dike far downstream from Patterson Avenue. The second location was under the overpass of Patterson. Following that was under the footbridge that begins Pfeffer Park. The fourth location was where the path and Collins Run intersected, and the final test site was at the very beginning of the bluffs. At each of the locations, we collected a constant amount of water, depending on the size of the containers ordered, and brought them back to the lab in Boyd Hall to be tested. We tested for nitrates and phosphates, two polluting compounds often found in water around heavily fertilized agricultural areas such as the drainage basin surrounding Pfeffer Park and its creek.
We determined that our final results are statistically sound by comparing the t-test results. If the t-tests result in less than or equal to .05 (alpha = .05), then there is no change in nitrogen levels as time passes. However, if the t-tests show a result of over .05, a statistical difference between the collected data is shown.
In order to have enough data to support our hypothesis, we needed to test the water once a week for six weeks. This method provided us with the necessary amount of information to get an accurate measurement of the nitrate and phosphate levels. We chose five locations along the creek to ensure that we did not get anomalous results from one specific location. We asked for advice during the idea process, and changed a few of our original experimental design ideas. For example, originally we were going to test water at both Pfeffer Park creek and Western Pond. However, we could not find a legitimate correlation between the two water sources, so we decided to focus our attention on the more natural one, Pfeffer Park creek. Also, the standing water of the Duck Pond does not allow fertilizer runoff to flow through its system, thus altering the possible results of testing in that location. One of the ways that we will ensure unbiased is by testing water at five different locations along the creek. Also, retrieving data each week for a number of weeks ensures unbiased results.
In order to collect data for the calculation of NPS pollution in the Pfeffer park creek, we collected samples of the water from the creek and tested them for levels of nitrates and phosphates. The gathering and testing of the water was facilitated by a few necessary materials including sample containers and phosphate/nitrate testing kits.
Containers used to hold samples of water were needed to physically hold the sample areas of water that we tested. We took ten containers each trip to Pfeffer Park in order to get the samples from the 5 different locations along the creek (2 sample containers per location). We will physically placed the containers in the water and filled it so that an ample amount of sample water was stored for testing in the lab. We went to the park once a week, on the same day each week, until the time to synthesize the results to test our hypothesis. Collecting samples from 5 different sections of the creek each time, we brought the containers back to the lab for immediate testing. The most important materials that will be used were the water testing kits. On each day that we gathered samples, we went into the peer science center and created the quantitative data that will be used to test our hypothesis. The testing that was involved showed us in a measurable fashion the amount of nitrates and phosphates (the majority of the makeup of harmful chemicals in streams that suffer from NPS pollution). Each sample was tested separately, and once all location samples were tested from each weekly gathering, we made arguments as to whether or not we reject or fail to reject our null hypothesis.
Because it is difficult and time consuming for the members of our group to walk to Pfeffer Park every week, we will needed the assistance of the class to go down to the creek to collect samples on the week that were available to us. They carried the ten containers and went to the specified areas along the creek and brought back samples from each area of the creek. In order to insure the proper steps in the testing process are kept intact, each member of our group will oversee the testing methods of our peers.
In conclusion, the weeks ahead offered us a valuable insight into the agricultural community around us and its effects on our water systems. We looked forward to gathering our information and testing our hypothesis.
We put the data we collected into Statview and ran descriptive statistics, paired t-tests and weekly mean results. From this we are able to determine if there is statistical difference from week to week.
We first looked at mean test results. The highest readings were taken in the first two weeks. There was then a gradual decline until week 4 when it leveled off and then dropped again on week 6. The readings were fairly low compared to what we expected. We had also hypothesized that the readings would decline over the collection period. This was true as the results indicated (shown in the line graph).
The results show statistical difference for more than half of the paired weeks. This means that the P-value was less than the alpha value (.05). Between each week there is little statistical difference but from week 1 to week 6 there is a great change. This shows there was the gradual weekly decline in phosphate levels but that over the entire collection period there was significant difference.
In looking the mean results of each week for the nitrate tests, we noticed that the levels of nitrates in the samples were very random in concentration. We only used 4 weeks of the testing due to inaccuracy of primary testing, however, the results showed an initial drop from week 3 to week 4 and then back up and back down in the following weeks.
There is significant difference from week to week, but the randomness of the pattern of the weekly results caused the overall deviation to show no significant difference. Because there is a lack of statistical difference in the results as a whole we must reject our hypothesis that the nitrate levels will decline over the collection period.
Discussion and Conclusions
Analyzing the data for the nitrate and phosphate levels, the results of our experiment seem varied. In regards to phosphates, our results proved that the chemical levels followed the pattern that we had predicted. Over time, the levels decreased. We believe that these statistics were the result of local agricultural practices. During the beginning of fall and the beginning of our results, local farms were still using chemicals on their crops. As time passed, agriculture began to slow and stop, resulting in the drop in phosphate levels indicated by our graphs. The gradual decline in agricultural practices showed itself in the gradual decline in chemical, specifically phosphates, levels.
Nitrate levels, on the other hand, were chaotic. We had predicted, like phosphates, the gradual decrease in chemical levels; however, results were random and appear to have no pattern. The results were problematic. After thought, the results we obtained from the Nitrate tests might be the effect of poor testing supplies. When testing for nitrate levels using the HACH kits, the amount of stream water that the test demanded was very low. Any small error in the amount of water to be tested in the test tubes could result in much higher or lower results. In short, the chaotic nature of the nitrate results may be the result of testing error. This idea, of course, is frustrating to acknowledge considering the great amount of time spent insuring proper testing techniques in order to attain the most accurate results.
Our report answered many of our questions, but raised several more. Although we believe we have answered why our nitrate tests resulted in random levels, we still question whether or not there was sufficient testing error to result in the chemical levels that we recorded. In addition, we noticed that, although the visual quality of the stream seemed to be very poor, nitrate and phosphate levels were generally low. Most testing days, the stream had algal blooms (some of which were orange) or the translucent rainbow qualities associated with petroleum runoff. The fact that these qualities were present led us to believe that non-point source pollution would be higher.
In suggesting further investigation, we would be interested in being able to extent the time period of our tests to include all of the seasons, as opposed to only autumn. Also, changing the testing locations to be more upstream or downstream would also be interesting.
In conclusion, we found that the pollutant levels of Collins Run were generally low, decreasing with time as we had expected, and the testing method proved difficult. Through the course of the semester, our group learned a great deal about the problems with our water supply and its causes and effects. We are looking forward to seeing future classes build upon our foundation and discover, as we did, the hidden systems of nature all around.
Au-Yeung, W.C.; Luk, G.K.; "Environmental Investigation on the Chemical Reduction of Nitrate from Groundwater." Advances in Environmental Research. Vol. 6, Issue 4. October, 2002.
Cairns, John; Niederlehner, B.R.. "Developing a Field of Landscape Ecotoxicology," Ecological Applications. Ecological Society of America, 1996.
Cox, William. "What is Nonpoint Source Pollution?" Environmental Protection Agency. Online. Available www.epa.gov/region4/water/nps/ Accessed 26 September, 2002.
Franz, Neil. "EPA Clean Water Plan Pits Industry Against Farmers." Chemical Week. 22 December, 1999.
Hess, Glenn. "EPA Find Ruling on Clean Water Act Is Seen As 'Contrary to Common Sense.'" Chemical Market Reporter. 17 July, 2000.
Karr, James; Magnuscn, John; McKnight, Diane; Naiman, Robert; Stanford, Jack. "Freshwater Ecosystems and Their Management: A National Initiative." Science. Vol. 270. 27 October, 1995.
Mainstone, C.P.; Schofield, K.. "Agricultural Management for Nonpoint Pollution Control, With Particular Reference to the UK." European Water Pollution Control. Vol. 6, Issue 3. May, 1996.
"Most States Ignore Lending Course of Water Pollution, NWF Finds." International Wildlife. National Wildlife Foundation. July, 2000.
"Ohio's Ground Water Quality Characterization Program: Nitrates in Ohio's Ground Water." Division of Drinking and Ground Waters. 2000.
Sarre, Alastair. "Toxic Algal Blooms A Sign of Rivers Under Stress." Nova: Science in the News. Australian Academy of Science. August, 1997.
Sekhon, G.S.; Singh, Bijay; Singh, Yadvinder. "Fertilizer-N Use Efficiency and Nitrate Pollution of Groundwater in Developing Countries," Journal of Contaminant Hydrology. 15 May, 1995.
October 18, 2002 Collect data from stream
October 25, 2002 Collect data from stream *
November 1, 2002 Collect data from stream
November 8, 2002 Collect data from stream
November 15, 2002 Collect data from stream
November 22, 2002 Collect data from stream November 29, 2002 Collect data from stream * November 30 Ð December 2 Process and evaluate data
* On these days, we will use our class to help collect and test data from the stream.
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