Nitrate levels have an effect on the chlorophyll levels in Campus Lake

Abstract

Algae Chlamydomonas is an example of a photosynthetic bacteria that produces chlorophyll in Campus Lake. Temperature can increase and decrease the activeness of the photosynthetic bacteria. Nitrate levels and chlorophyll levels were recorded for four seasons. Nitrate and chlorophyll levels were highest in the summer and lowest in the winter. The temperature was also highest in the summer and lowest in the winter. Nitrate levels impact the chlorophyll levels in Campus Lake.

Introduction

The purpose of this study was to determine if nitrate levels impacted the chlorophyll levels in Campus Lake from Spring 2009 – Winter 2010. This time frame was selected, because it was a full calendar year with all four seasons. Nitrate, NO3, is the form of nitrogen that can be used by plants to convert to nitrogen for heterotrophs. Chlorophyll is found in autotrophs and can be used as a relative measure of autotrophic concentration (Wischusen, 2009). It was hypothesized that the nitrate levels will positively impact the chlorophyll levels in Campus Lake. If the hypothesis is true, as nitrate levels increase, chlorophyll levels will also increase.

Materials and Methods

Measurement of nitrate production was performed using sample water from Campus Lake, NitraVer3 Reagent, and NitraVer6 Reagent. 5 mL of sample water was put in a test tube and NitraVer6 Reagent was added to it. The test tube was shook for 3 minutes and incubated for 30 seconds. After incubation, the sample was poured into a viewing tube but was poured very carefully, so no settled cadmium particles transferred to the viewing tube. NitraVer3 Reagent was added to the same viewing tube with the sample. After adding the second reagent, the tube was capped, shook for 30 seconds, and incubated for 10 minutes. A red color developed meaning nitrate was present. After incubation, the tube was inserted into the top-right opening of the color comparator. A second viewing tube was filled with sample water and inserted into the top-left opening of the comparator. While holding a light and viewing through the opening in the front of the comparator, the disc was rotated to obtain a color match. The mg/L nitrate nitrogen was recorded through the scale window.

Chlorophyll levels were determined by inverting the water sample from Campus Lake into a BÜchner funnel that already contained a glass microfiber filter and 25 mL of dH2O. After inverting, the water sample was filtered through the BÜchner funnel. The filter was placed in a test tube after these steps. 10 mL of acetone was added to the test tube and secured with a stopper. The tube was vortexed for 60 seconds. A Whatman #1 filter was then placed in a funnel and put in a spectrophotometer test tube. The entire extracted sample was then added to the filter and filtered into the test tube. After blanking the spectrophotometer correctly, the absorbance was recorded of the test tube with the sample.

Results

The variables that were recorded were seasons and temperature (abiotic) and nitrate and chlorophyll levels (biotic). Chlorophyll levels were determined by the absorbance reading in the spectrophotometer, and nitrogen production was recorded through the scale window of the comparator. The amount of chlorophyll in the lake represents photosynthetic bacteria and other autotrophs. In the summer of 2009, nitrate and chlorophyll levels were the highest. In the winter of 2010, the nitrate and chlorophyll levels were the lowest. At high temperatures, there were higher levels of nitrate and chlorophyll. At low temperatures, there were lower levels of nitrate and chlorophyll. (Table 1) and (chart 1).

| Spring 2009 | Summer 2009 | Fall 2009 | Winter 2010 | Temperature | 15.2 C | 35.2C | 32.3C | 13.19C | Nitrate Levels | .02 | .03 | .02 | .001 | Chlorophyll Levels | .04 | .12 | .07 | .02 | Table 1. Temperature and Nitrate-Chlorophyll Levels in Campus Lake in a Full Calendar Year

Chart 1. Nitrate-Chlorophyll Levels in Campus Lake in a Full Calendar Year

Discussion

In this experiment, the alternative hypothesis was favored. Nitrate levels did seem to effect chlorophyll levels in Campus Lake. As shown in Table 1, the lowest nitrate level had the lowest chlorophyll level, and the highest nitrate level had the highest chlorophyll level. Also, temperature does affect the levels, because the highest temperature had the highest nitrate level and highest chlorophyll level, and the lowest temperature had the lowest nitrate and chlorophyll levels. As temperature decreases, the amount of sunlight usually decreases as well which slows down productivity and the autotrophs also slow down their biological functions. No source of error was noted, because average charts with the temperature, chlorophyll levels, and nitrate levels were handed out. If future projects were to be carried out and no errors occurred, the same result would be seen. Using pH as the abiotic factor could have performed another experiment. As the temperature increased or decreased, the pH also increased or decreased with the temperature. If pH was high, then chlorophyll and nitrate levels were also high. This also supports the alternative hypothesis that was favored. Since bacteria convert nitrate to nitrite, nitrite poisoning can occur in some animals. Nitrate in water, however, is usually harmful (Zublena et. al., 1997).

Literature Cited

Wischusen, W., A.D. Jolissaint, J. Reiland, and S. Pomarico. 2009. Biological Laboratories. Hayden-McNeil Publishing, Plymouth, Michigan.

Zublena, J.P., M.G. Cook, and M.B. St. Clair 1997, <Pollutants in Groundwater: Health Effects, http://www.soil.ncsu.edu/pubications/Soilfacts/AG-439-14/> April 20, 2010 3:30 PM CDT.