Investigation of Water and Soil Quality Upstream and Downstream in a Pond Environment
It's a legend around these parts that my neighborhood, Walker Gordon Farm (WGF), was once the residence of Elsie the Cow, the distinguished ungulate whose travels yielded over $10 million for the war effort during the Second World War. Flash-forward 60 years, and WGF is a bustling suburban development with its own tennis courts, a clubhouse, and a modest swimming pool. However, in other areas of the expanse, things have remained relatively the same. Whether you are passing by car or taking a morning jog, it is hard to miss the pond, whose situation seems rather aloof from the rest of the neighborhood. There are no big houses, paved driveways, or fancy gardens. The pond abounds with vegetation, and on my first visit I spotted at least 10 different species of flora. Some of the wildlife taking residence in the area are squirrels, rabbits, white-tailed deer, several species of birds, and many water-dwelling insects.
From another perspective, the pond can be viewed in two separate sections. Rainfall accumulates in the pond within the basin-shaped "upper," or upstream, area. The water then flows away from Plainsboro Road, where it eventually reaches a man-made barrier that resembles a raised rectangular surface. From there, the water flows steadily into a reservoir-shaped area, which I call the "lower" or downstream area. After observing these two areas, I noticed that the upstream area seemed to be more polluted than the downstream part of the pond. The stench of a nearby pharmaceutical company, Firmenich, was pungent here, and there was, unfortunately, evidence of littering. A black pipe runs through the bank of the river, and there were discarded paper cups along the underbrush.
In contrast, the downstream region seems more idyllic: plants with blooming flowers are more prevalent, and the entire area has an untarnished feel to it. Seeing such distinct differences between these two areas of the same pond, I began to wonder how the flow of water and rainfall impacted the water quality of the pond. I hypothesized that the downstream area of the pond would be a more suitable environment for sustaining plant and animal growth than the upstream region, since the water seems to undergo a gradual purification as it flows downstream. Also, vital minerals and nutrients would more likely accumulate downstream because of the direction of the water's flow.
To test my hypothesis, I decided to visit the pond at least once a week, alternating between the upstream and downstream areas. I proceeded to record my observations in a field journal, and also took down sketches and photographs of both areas of the pond using a pencil and a digital camera.
After my initial observations, I selected a day when I could collect water samples as well as soil samples in both the downstream and upstream areas of the pond. Because the climate and temperature of my area varies from day to day, it was necessary to gather all my key data from both sites under similar weather conditions. First, I collected two water samples, one each from upstream and downstream, using two 200ml plastic containers. I then tested both samples for free and total chlorine, iron, copper, total nitrate and nitrite, pH and alkalinity, and total hardness using the WaterWorks™ School Test Kit. I utilized the recommended data for aquatic organisms from the Water Quality Control Division of the Colorado Department of Public Health and Environment (CDPHE-WQCD), found at the BASIN project's Web site. Additionally, I used the recommended data from H 2 O University's Web site, which is a compilation of several water-quality criteria reports by a number of institutions, including the EPA. This data would serve as the control group in my water-quality testing and would help me decide which part of the pond was more likely to support life. I hypothesized that the downstream water would be of a quality closer to the CDPHE-WQCD standards than the upstream sample. The table below contains data from my water-quality testing. The results are compared directly to the CDPHE-WQCD recommendations for each respective test.
My water sample results revealed that differences between upstream and downstream were relatively subtle. The only significant differences were in the nitrite (0.3 ppm and 0.0 ppm) and total hardness (50 ppm and 120 ppm) levels for upstream and downstream, respectively. Comparing these to the CDPHE-WQCD regulations, the water from downstream seems to be slightly better in quality. However, such small differences are probably insignificant. Overall, the data from the water test neither supported nor discredited my hypothesis, since the water quality of both areas was too similar to truly distinguish.
I tested the water samples for the following indicators of water quality, using the WaterWorks™ School Test Kit:
Chlorine: Although chlorine is necessary for disinfecting water, free chlorine, which is the amount of chlorine gas dissolved in water, is toxic to fish and aquatic organisms, even in very small amounts. Decaying materials in water can combine with chlorine to form compounds called trihalomethanes, which are carcinogenic to people. Furthermore, chlorine is more toxic in waters with lower pH levels. The recommended maximum total chlorine level is 0.01 ppm for all aquatic life (H 2 O University, 2004). Levels higher than that can cause death in many fish and other aquatic organisms. The data from the water samples was 0.1 ppm and 0.1 ppm for free chlorine, and 0.2 ppm and 0.2 ppm for total chlorine. Both sites exceeded the recommended maximum levels.
Nitrate/nitrite: All organisms require nitrogen for growth and reproduction. Nitrate (NO 3 ) is highly soluble in water and is stable over a wide range of environmental conditions. Nitrite (NO 2 ) is ephemeral in water because it is quickly transformed to nitrate by bacteria. Excessive concentrations of nitrate or nitrite can be detrimental to aquatic life, causing "brown blood disease" in fish (BASIN, 2005). A nitrate level exceeding 10 ppm is hazardous to most organisms. The results for total nitrate were 2.0 ppm and 2.0 ppm. The results for nitrite were 0.3 ppm and 0.0 ppm. Both results are within CDPHE-WQCD recommendations.
Iron: Iron is a trace element required by both plants and animals. As a mineral primarily found in the ground, iron can still adulterate bodies of water. The effect of iron on water quality is largely contingent on water hardness. Although iron is essential to life, levels above 1.0 ppm can be dangerous to aquatic organisms (RAMP, 1997). Neither the upstream nor the downstream sample contained any iron, so the data is within the water-quality standards.
Water hardness: Hardness is the measure of polyvalent cations in water and usually represents the concentration of calcium and magnesium ions, since these are the most prevalent in water. "Harder" water usually lowers the potential hazard of other metals to aquatic life (BASIN, 2005). However, water that is too "hard" can also be harmful to aquatic life. The data for hardness was 50 ppm and 120 ppm. Because hardness varies with environment, no standards exist for it.
pH: The pH scale ranges from 0 to 14 and is a measure of the activity of hydrogen ions. Water with a pH of 7 is considered neutral; levels above 7 are basic, while a pH below 7 is acidic. According to the CDPHE-WQCD, a pH range of 6.5 to 9.0 is optimal for most aquatic organisms. The pH levels in my downstream and upstream data were both 6.0, which is slightly below the recommended range.
Total alkalinity: Alkalinity refers to the ability of water to resist changes in pH. Waters with low alkalinity are more likely to show changes in pH. Waters with high alkalinity are able to resist fluctuations in pH (BASIN, 2005). The water collected from both downstream and upstream showed 0.0 ppm of alkalinity. Because alkalinity varies greatly geologically, there are no standards for it.
Copper: Like iron, copper's impact on water quality is largely dependent on water hardness. Generally, small amounts of copper do not pose a threat. According to the EPA, however, copper levels exceeding 1.3 ppm can be a potential hazard to aquatic organisms. The copper levels for my tests were 0.1 ppm and 0.0 ppm, both of which are within the recommended EPA range.
After analyzing and comparing my water-quality data to the recommended standards for each test, I decided to supplement my numerical figures with a microscopic investigation of the water samples, which yielded fascinating results. Although my data indicated that the water downstream was slightly more suitable for living organisms, an in-depth search for microorganisms showed otherwise. While I could not identify the microscopic contents of my downstream sample, I was able to identify the microorganism in the upstream sample as belonging to the genus Spirogyra. This discovery contradicted my original hypothesis that the downstream area would be more suitable to sustain plant and animal life.
For my soil-quality tests, I took eight soil samples (four each for upstream and downstream) from the sites drawn in my field journal. Using plastic Ziploc® bags, I gathered several handfuls of soil for each site, and labeled each bag according to the area from where I gathered it. I then tested each sample for pH, nitrogen, phosphorus, and potassium using Mosser Lee's Soil Master™ Kit. I further hypothesized that the soil from the downstream area of the pond would consist of nutrient content similar to the levels required to sustain rudimentary plant development. I used the table below to organize my data.
My soil sample results revealed a significant difference between the upstream and downstream areas. The upstream samples had an average pH of 5.875, while the average downstream pH level was 6.875. This indicates that the downstream site is more suitable for supporting life, since most organisms survive optimally between pH levels of 6.5 to 8.2 (Water Chemistry, 2005). Phosphorus levels were also higher in the downstream sites, which further supports my hypothesis.
I tested the soil samples for the following indicators of soil quality, using the Water Mosser Lee's Soil Master™ Kit:
Nitrogen: Nitrogen is an important element in chlorophyll, giving plants their deep green color. It is important in growth and development of fruit and maturity. However, higher levels of nitrogen can cause weaker stems or delayed development in plants. Nitrogen levels were on average low in both upstream and downstream areas.
Phosphorus: Phosphorus encourages sturdy root development and resistance to disease. It is important for the growth of beneficial soil bacteria. Phosphorus levels were on average low in upstream and medium in downstream areas.
Potassium: Potassium plays a vital role in biochemical and physiological functions. It enhances disease resistance, improves fruit size, texture, flavor, and helps moderate the effects of drying and stress. Potassium levels were on average medium in both upstream and downstream areas.
pH: A pH range between 5.5 and 7.0 provides an ideal balance between microbial activity and nutrient availability. Healthy soil will have a pH between 6.2 and 6.5 (Tynes, 2005). However, many plants grow well in soils with pH values between 6.0 and 7.0. The upstream samples had an average pH of 5.875, while the average downstream pH level was 6.875.
In retrospect, several factors could have affected the results of my experiments, including environmental conditions, selection of sampling sites, and the equipment used. Furthermore, because the preferences of different plants and animals vary in nature, it is hard to determine if one environment is more able to support life than another.
Although water and soil quality in the downstream site were indeed closer to the standard recommendations than the upstream data, my initial hypothesis, which proposed that the downstream area of the pond would be a more suitable environment for sustaining plant and animal growth, is inconclusive, due to different preferences within animals and plants. Nonetheless, several parts of my investigation lent credence to my hypothesis. For instance, Photinia pyrifolia, a plant found in both the downstream and upstream habitat, has a pH tolerance level between 5.5 and 7.5. However, the plant grew noticeably better downstream than it did upstream. This is a direct correlation between the quality of soil and the growth of the plants present in a specific area. The soil upstream had an average pH level of 5.875, which was on the lower end of Photinia pyrifoliai's tolerance level. On the other hand, the soil downstream, which had an average pH level of 6.875, was in the midrange of Photinia pyrifoliai's tolerance level, an indication of optimal soil conditions. Indeed, the Photinia pyrifoliai growing downstream had more berries and greener foliage than the same plant growing upstream.
Even though the growth of Photinia pyrifoliai in both areas of the pond supports my initial hypothesis, not all plants will grow better downstream than upstream. For instance, a plant that requires an acidic habitat will probably survive better upstream than downstream.
Throughout the course of the next year, I hope to continue gathering data, as that will help me determine a more evident pattern between plant and soil quality and the different seasons of the year. Although the future of my scientific endeavor is uncertain, I am quite sure about one thing: in science, anything is possible.
Harley, S. "Water Quality Testing." PFRA Online, 28 October 2003. Retrieved from the World Wide Web on 9 October 2005.
"Impact of Water-Level Fluctuations on Aquatic Plants." St. Lawrence Centre, 24 August 2005. Retrieved from the World Wide Web on 9 October 2005.
"Important Water Quality Factors." H 2 O University, 19 February 2004. Retrieved from the World Wide Web on 25 January 2006.
"Information on Water Quality Parameters." City of Boulder/USGS Water Quality Monitoring. BASIN, 24 December 2005. Retrieved from the World Wide Web on 25 January 2006.
Schaaf, Sherry. "Water Quality Testing." Washington Virtual Classroom. Retrieved from the World Wide Web on 9 October 2005.
Tynes, Mary J. "Benefits of Healthy Soil." Master Composter, 2005. Retrieved from the World Wide Web on 11 December 2005.
"A Virtual Pond Dip." Microscopy U.K. Retrieved from the World Wide Web on 25 January 2006.
"Water Chemistry: Data Interpretation and Standards." Western Upper Peninsula Center for Science, Mathematics and Environmental Education, 2005. Retrieved from the World Wide Web on 11 December 2005.
"Water Quality Parameters." River Assessment Monitoring Project, 1997. Retrieved from the World Wide Web on 25 January 2006.
More About This Resource...
Supplement a study of earth science with an activity drawn from this winning student essay.
- Send students to this online article, or print copies of the essay for them to read.
- Have them write a one-page reaction to the essay. Were they surprised to learn that the water quality upstream was better? Why or why not?
OriginYoung Naturalist Awards
SubtopicMinerals and Resources