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Testing the Water Quality of President's Pond

Brett Bowersox and Byran Berkompas | Biology 345 | December 11, 1998

Introduction | Methods | Results | Discussion | Figures | Tables

INTRODUCTION

Our goal was to evaluate the quality of the water in President's Pond on the campus of Calvin College, Grand Rapids, Kent County, MI. We did this as part of a survey of the ponds health for Calvin's CEAP Project.

METHODS

We chose four sites on President's Pond in order to get an accurate sampling of the water quality. (Figure 1) We chose site 1 because it is near to the area of input from Ravenswood Pond. Site 2 was in the middle of the lake. Site 3 is near the drain outlet underneath Lake Drive and site 4 is near an input from Calvin's soccer fields. We collected and tested our samples on September 29, October 27, and November 17. The samples were collected between 12:00 PM and 2:00 PM and tested shortly after. The water samples were collected using a La Motte Sampler (Code 1077). We took a sample at a depth of 30 cm and a sample at 20 cm from the bottom at each site. The samples were stored in Whirl-Paks and the pH was tested immediately using colorpHast pH strips. The water temperature and dissolved oxygen levels were measured using a YSI Inc. (model 55/25) dissolved oxygen meter. On September 29 the temperature and dO were only measured at the water sample depths. On October 27 and November 17 we tested the entire water column at intervals of .5 m. In the laboratory, we tested for Ammonia, Phosphate, Nitrate, Alkalinity, Chloride, Total Hardness and the Hardness (Ca). Hardness (Mg) was determined by subtracting Hardness (Ca) from the Total Hardness. On September 29, Hardness (Ca) and (Mg) were not determined.

The Total Hardness was tested using Hach Kit model HAC-DT. A ManVer 2 powder pillow was added to 25 mL of sample water and 75 mL of demineralized water. The sample was titrated using a Hach digital titrator (model 16900) with a 0.08 TiraVer (Sodium EDTA) cartridge until it changed from red to pure blue. The number on the titrator was multiplied by 0.4 to determine the Total Hardness. The Hardness (Ca) was tested with the same kit and the same procedures but with a CalVer2 Calcium Indicator powder pillow. The solution was titrated with the same cartridge until it changed from pink to blue. (Hach 107-8)

The Alkalinity was tested using Hach Kit model AL-DT. A Bromcresol Green-Methyl Red powder pillow was mixed into 25 mL of pond water and 75 mL of demineralized water. The treated sample was then titrated with a 0.16 Sulfuric Acid cartridge until the solution turned blue-gray. The number on the titrator was then multiplied by 0.4 to determine the Alkalinity of the pond water. (Hach 33-5)

The Chloride was measured using Hach Kit model CD-DT. 25 mL of pond water and 75 mL of demineralized water were mixed with a Diphenylcarbazone powder pillow. The treated water was titrated a 0.2256 Mercuric Nitrate cartridge until the solution changed from yellow to light pink. The digit multiplier was 0.4. (Hach 53-5)

We used Hach Kit model NI-8 to test for Ammonia. Three drops of Nessler Reagent were added to 5 mL of pond water and allowed to sit for 5 minutes. The treated water was then placed in a color comparator along with an untreated 5 mL sample and viewed through an Ammonia Nitrogen Color Disc 0-3 ppm. The colors were matched and the number on the disc was multiplied by 1.2 to determine the Ammonia concentration.

The Phosphate was tested with Hach Kit model PO-19. A square mixing bottle was filled with 20 mL of pond water with a PhosVer 3 Phosphate Reagent powder pillow and allowed to develop for 8 minutes. If a blue color developed then Phosphate was present. 5 mL of the treated sample was poured into a viewing tube and compared with an untreated control in a color comparator with a Phosphate Color Disc 0-50 ppm. The number on the wheel was divided by 50 to determine the concentration of Phosphate.

Nitrate was tested with Hach Kit model NI-14. A sample tube was rinsed twice with pond water. A NitraVer6 Nitrate Reagent powder pillow was added to 5 mL of sample water and shaken for 3 minutes then allowed to sit for 30 seconds. The treated sample was carefully poured into a second tube to remove cadmium particles. A NitraVer3 Nitrite Reagent powder pillow was added and the tube was shaken for 30 seconds. If a red color developed then nitrate was present. Color was allowed to develop for 10 minutes. The treated sample was compared with an untreated control in a color comparator with a Color Disc (Low Range Nitrate Nitrogen). The scale on the disc was multiplied by 4.4 to determine the Nitrate concentration.

RESULTS

The Total Hardness increased throughout the fall of 1998. (Figure 2) The Ca percentage of the Total hardness also increased. The Hardness (Mg) increased very slightly.

Alkalinity dropped sharply from September to October. It increased slightly from October to November. Overall the Alkalinity concentration dropped. (Figure 2)

The concentration of Chloride decreased slightly between September 29 and October 27. It then remained static through November 17. (Figure 2)

The Ammonia levels fluctuated throughout the fall with the lowest reading on October 27. (Figure 3)

pH ranged from 7.5 to 6.5. The pond is generally neutral.

The secchi depth increased between September 29 and October 27 and decreased slightly in November. (Figure 4) Generally, the secchi depths increased 15-20 cm throughout President's Pond from September to November.

The average water temperature in President's pond decreased at a linear rate. The average dissolved oxygen levels increased throughout the fall. The greatest increase happened between September 29 and October 27.

We did not detect any Phosphate or Nitrate.

DISCUSSION

The water in President's Pond was relatively hard at the beginning of the fall and it was extremely hard by the end of our testing. Extremely hard water can make fish more susceptible to toxic metals but the ions that cause hardness are necessary for plant growth. (Lind 67) The hardness is high but not excessively dangerous to biota.

Alkalinity levels are high but within the normal range for natural lakes. (Lind 63) At the current levels, the Alkalinity does not adversely affect the water quality in President's Pond.

The Chloride levels are quite high. This is not uncommon in lakes near roads that are treated with road salts during the winter months. (Lillie 22)

The Ammonia concentrations are quite good. Levels under 1 ppm are considered good. High levels of undissociated NH4OH are toxic. (Lind 84)

Natural concentrations of Nitrate are frequently less than 1 ppm. (Lind 85) President's Pond had no detectable level of Nitrate and that is unusual. Macrophytes and Phytoplankton populations are held back by the low Nitrate concentrations and the lack of Phosphate. In unpolluted water, Phosphate levels are frequently less than .1 ppm. (Lind 78) In President's Pond there is no detectable Phosphate. Phosphate and Nitrates are the most influential limiting nutrients in aquatic systems.

The secchi depths indicate that there is an ongoing high level of production. It is an issue of debate what depths are acceptable for good water quality. Some scientists think that good water quality is indicated by high productivity therefore low readings are good. Others think that water clarity is an indicator of quality and they look for high depths.

As expected the temperature falls as the average air temperatures fall. The dissolved oxygen levels rise with the falling temperatures. This is because cold water has a higher carrying capacity for dissolved oxygen than warm water. Dissolved oxygen levels below 3 ppm are considered hazardous. (Lind 72)

Overall, the water quality in President's Pond is hard to categorize as good or bad. The Chloride and Hardness levels are well above average in comparison to other ponds we looked at in Wisconsin. We did not find any evidence that these levels are hurting the ecosystem but the possibility exists. We know that Phosphorous and Nitrate are in the pond because the pond is quite green and that indicates good production levels. We do not know why our tests could not detect Phosphate or Nitrate. The pH and Ammonia are well within healthy parameters for aquatic life.

In future studies we would recommend using a more sensitive test method for Nitrate and Phosphate. Inputs from East Grand Rapids and Lake Drive should be studied to determine where the Chloride and CaCO3 are coming from. If these levels continue to rise, the health of the ecosystem may suffer.

Works Cited

Lind, Owen. 1985. Handbook of Common Methods in Limnology. Kendall/Hunt Publishing Company, Dubuque, Iowa

Lille, Richard A., Mason, John W. 1983. Limnological Caracteristics of Wisconsin Lakes. Technical Bulletin No 138 DNR Handbook


FIGURES

Figure 1

Figure2 Figure3
   
Figure4 Figure5