## The Effects of Nitrates on the Growth of Algae in Nahr El-Kalb

Sami Bashour

Sami Shatila

American Community School at Beirut, Lebanon

**[Abstract]{.underline}**

This experiment was performed to test the factors that affect the growth
of algae in rivers, specifically that in Nahr El-Kalb. A number of
Globe-based protocols were implemented to test for the following
factors: pH, Nitrate levels, water temperature, and alkalinity. These
were measured on a weekly basis to determine what causes the excessive
growth of algae. Our group hypothesized that with the increase of
nitrogen levels in the river, due to fertilizers from the farming
season, the growth of algae will increase. However, we also predicted
that after this year's anomalous heavy snowfall during the winter
season, the habitual snowmelt, which would primarily empty out into the
river, would dilute the concentration of nitrates. Thus, the growth of
algae would not appear to grow at an alarming rate that may threaten the
ecosystem. With this in mind, from our most recent data we have observed
that the conglomeration of nitrates is relatively low, and does not pose
a serious long-term risk if this predicted situation continues to occur.
Nevertheless, a possible further investigation could be to probe the
sources of nitrates and other chemicals that may contribute to the
rise/fall in pH, and water temperature -- the same factors that
contribute to the growth of algae in Nahr El-Kalb.

**[Research Question/Hypothesis:]{.underline}**

Over the years algae has been observed at Nahr El-Kalb as the water
level of the river drops in May and June. Nahr El-Kalb is located just
north of Beirut, running into the Mediterranean Sea. It is one of three
major farming rivers in Lebanon, coming third only to the Orontes, also
known as the Assi, and the Litani River. Nahr El-Kalb is a seasonal
river. The river is dry in the summer and fall, however, quickly fills
up as rain falls and the snow on Mount Lebanon melts. Usually, the end
of the snowmelt corresponds with the start of the faming season, and
therefore, nitrates (and other nutrient levels) become quickly
concentrated because there is both less water and more nutrients. The
Globe members hypothesized that the nitrate concentration would rise and
there would be visual evidence of algal blooms.

Because farms are located around Nahr El-Kalb, the erosion of the soil
brings fertilizers into the river. The most common fertilizers used in
Lebanon contain high levels of nitrates, for instance ammonium nitrate,
which contains fifty percent nitrate and fifty percent ammonium (I.
Bashour, personal interview, 22, 6, 2003). In the late spring or early
summer, two species of algae are normally seen in Nahr el Kalb, which
led to the hypothesis that high levels of nitrates would help the algae
grow more rapidly. The first species is one that floats on top of the
river and changes the color of the water to green (J. LeAnderson,
personal interview, 15, 4, 2003). The second attaches to the bottom of
the river and forms pillow-like structures.

A relationship between nitrates and algae is hypothesized because algae
need the nitrogen in the nitrates to grow and multiply.

Algae are primary producers in the fresh water ecosystem and serve as
food for fish and other animals that live in the water (Algae, the World
Book). All species of algae contain chlorophyll.  They help purify the
air and water by the process of photosynthesis (Algae, the World Book).
However, some algae multiply rapidly in polluted lakes and rivers
presumably due to pollution from farms or factories located around the
river containing high levels of nitrates, phosphates, and magnesium
(Algae, Encarta). This is very important because with the increase of
pollution in Nahr El-Kalb, presumably, thick layers of algae, seen in
recent years, will form when waste materials, such as fertilizers
(containing nitrates), are dumped in the water because the algae feed on
the nutrients such as phosphorous, magnesium, calcium, and nitrates in
the materials ("Tropical Aquatic and marginal Aquarium Plants"). Knowing
that Nahr el Kalb is a farming river and that fertilizers used in
Lebanon contain nitrates led to the hypothesis: to what extent do
nitrates contribute to the growth of algae in Nahr El-Kalb?

**[Research Method:]{.underline}**

The approach taken to answer the stated hypothesis was to perform weekly
tests and observations using GLOBE protocols. The tests most directly
related to the study were a thermometer to test the water temperature,
the La Motte -- Low-Range Test to test the level of nitrates in Nahr
El-Kalb, and Turbidity tube to test the water's transparency. Nitrates
were tested to determine their direct influence on algae growth. Also,
The transparency was determined by the use of the Turbidity Tube. The
Tube was filled up with water that was slowly released until the black
and white pattern on the bottom of the Tube was recognizable. After the
observer was able to see the pattern, the measurement (in centimeters)
was shown on the side of the Tube. Furthermore, temperature also plays a
role in algae growth because under certain temperatures algae grows more
rapidly, and the transparency of the river allows for visual evidence of
the algae growth. The other GLOBE protocols such as a Ph meter to test
the water's Ph level and the La Motte kit to test the alkalinity of Nahr
El-Kalb were used for background research on the conditions in the
river. These tests have been preformed for a period of three months at
Nahr El-Kalb. The reasoning behind starting in March was because it was
assumed that the nitrate levels would rise with the start of spring and
the farming season, however, because of the extended winter, the large
amounts of fertilizers usually added to the soil were not, and nitrate
levels did not drastically change. The site of experimentation is
located approximately halfway between the restaurant, Nahr El- Founoun,
and a highway bridge on the South side of the river at a height of 2.8
meters.

**[Data Summary:]{.underline}**

Over three months of tests and observations, the GLOBE members learned
that not only do nutrients affect the growth of algae, but so does the
water velocity. In this section, the pictures depict the decreasing
water levels over the three months, and the graphs show the levels of
nitrates, water temperature, water transparency, water alkalinity, and
the river's pH.

  --------------------------- -------------------------------------------
  **DATE**                    **Algae Observed**

  *9/3/2003*                  No

  *16/3/2003*                 No

  *22/3/2003*                 No

  *28/3/2003*                 No

  *6/4/2003*                  No

  *13/4/2003*                 No

  *20/4/2003*                 No

  *27/4/2003*                 No

  *4/5/2003*                  No

  *11/5/2003*                 No

  *18/5/2003*                 No

  *25/5/2003*                 No

  *1/6/2003*                  No

  *8/6/2003*                  Yes

  *15/6/2003*                 Yes

  *22/6/2003*                 Yes
  --------------------------- -------------------------------------------

Table 1. Algae Observation

![](media/image1.png){width="1.9375in" height="1.4583333333333333in"}
![](media/image2.png){width="1.9215277777777777in"
height="1.4458333333333333in"}
![](media/image3.png){width="1.9430555555555555in"
height="1.4527777777777777in"}

4-20-2003 4-27-2003 5-04-2003

![](media/image4.png){width="1.8493055555555555in"
height="1.3770833333333334in"}
![](media/image5.png){width="1.8541666666666667in"
height="1.3958333333333333in"}
![](media/image6.png){width="1.8229166666666667in"
height="1.3854166666666667in"}

5-18-2003 5-25-2003 6-01-2003

![](media/image7.png){width="1.8743055555555554in"
height="1.4055555555555554in"}
![](media/image8.png){width="1.8229166666666667in"
height="1.3541666666666667in"}

6-08-2003 6-22-2003

![](media/image9.wmf)

Graph 1. Nitrate levels in Nahr El-Kalb

![](media/image10.wmf)

Graph 2. Water Temperature in Nahr El-Kalb

![](media/image11.wmf)Graph 3. Water Transparency of Nahr El-Kalb

![](media/image12.wmf)Graph 4. pH levels of Nahr El-Kalb

![](media/image13.wmf)Graph 5. Water Alkalinity in Nahr El-Kalb

**[Data Analysis:]{.underline}**

Throughout the three months of tests, important data such as nitrate
levels, water temperature, and water transparency were acquired along
with the water alkalinity and pH of Nahr El-Kalb. The graph above shows
that in the first two weeks of testing, the nitrate level was at a
constant 0.4 mg/L nitrate-nitrogen. However, in the following week the
nitrate levels dropped to 0.3 mg/L and remained at that level for the
two subsequent weeks. Nevertheless, as was expected the nitrate levels
again dropped to 0.2 mg/L, however, this time for only one week, then
rose back up to 0.3 mg/L, where it maintained that constant for two
weeks. Again, as the pattern depicts, there was a slip in the nitrate
levels, where for the remainder of four weeks the level has been at 0.1
mg/L. The mentioned data proves that the nitrate levels remained low
throughout the entire study. The other tests that were carried out
through the duration of the three months also gave interesting results.
For instance, that water alkalinity levels, or concentration of
dissolved limestone in the water, showed that there is an average of
about 206.4 parts per million (ppm). The remainder of the data collected
at the site was more observational. For example, the pH of Nahr El-Kalb
was determined by inserting a pH meter into the water and waiting until
a constant pH level was observed on the screen. Over the past three
months the average pH level is 8.2 (slightly basic). Also, the water
temperature with an average of 12.5 was determined by placing a
thermometer into the river, which began to increase during the final
months of the study. The final test carried out at the site was the
water transparency. Throughout the duration of the three months the
transparency was not constant, but varied, dropping in the middle of the
study and then increasing at the end. It is assumed that with the excess
water entering the river from snowmelt, washed away much of the dirt,
bringing down the water transparency. However, the increase in the
transparency is because of the growth of a specific species of algae,
one that floats along the surface of the river. Despite this data, no
physical evidence that nitrates or any other nutrients affect algae
growth was proven. The only reason water transparency plays a major role
in this experiment is because the only way to prove or disprove the
hypothesis is by having physical or visual evidence of its existence.
Recently however, as the water levels decrease, small amounts of algae
have been spotted in the past two weeks. A factor in the delay of algae
growth is the sustained low temperatures throughout the season because
of the long winter, resulting in large amounts of snowfall and as the
snow melted, freezing water entered the river, keeping the temperatures
quite low. The lowest temperature was 11°C, only 2.5°C from the highest,
14°C. However, during the final weeks of the study, as the temperature
rose, evidence proving that algae depend on the heat of the summer to
raise water temperatures to a beneficial climate. The current or water
velocity was a variable that potentially affected the growth of algae in
Nahr El-Kalb. This is because it may have prevented the algae from
attaching to the riverbed or detaching after growth, thus removing the
possibility of being seen during data collection. The results obtained
could have been affected by many factors of error such as the untidiness
of the tools and instruments used.

**[Conclusions:]{.underline}**

The GLOBE members hypothesized that with the rise in nitrate levels, a
copious amount of algae would be seen. However, this hypothesis was, for
the most part, disproved. The fact that after testing nitrate levels,
and realizing that they are low, small amounts of algae were presumed to
appear. However, this is not the case because farther down stream, large
amounts of algae were seen. High nitrate levels were not seen this year
in Nahr El-Kalb because of the extended winter. Usually, spring
corresponds with the start of the farming season. Nevertheless, because
of the lack of spring this year, farmers were reluctant to use
fertilizers, which contain nitrates and other nutrients that effect
algae growth for fear that the rain would wash them away. Therefore, the
erosion of the topsoil by rain and snowmelt brought minimal amounts of
nitrates from those farms that used fertilizers on their crops. As
mentioned earlier, Nahr El-Kalb is a farming river, for this reason the
nitrate levels in it are viewed as relatively low. However, the nitrate
levels in Nahr El-Kalb would be viewed as extremely high if it were a
typical river (J. LeAnderson, personal interview, 14, 3, 2003). In this
experiment, the data was very different from what would be expected,
because of the unusually high-rate of snowfall, snowmelt, and rainfall
this year that went from a yearly average of about 860-900 mm to about
1040 mm on the coastline (M. Nimah, personal interview, 22, 6, 2003).

**[Discussion:]{.underline}**

There are numerous suggestions as to how to improve the experiment's
design. First of all, as mentioned earlier, this year was not an average
year, therefore leading to abnormal levels of various nutrients in Nahr
El-Kalb. Also, the study could have been more thorough if the river was
tested for other nutrients that algae depend on, like phosphorous and
magnesium, not only nitrogen. Furthermore, algae multiply in the
presence of pollution, so, it would have been logical to search for any
sewage outlets into the river. The final suggestion to improve the
experiment's design would be to have more than one study site, perhaps
one further down the river and the other further up. This is because on
Sunday the 22^nd^ of June, copious amounts of algae were located further
down the stream where the water velocity was much less because the high
speeds of water prevent the algae from taking hold in the river.

**[Bibliography]{.underline}**

\"Algae.\" [The World Book Encyclopedia]{.underline}. 3rd ed. Vol. #1.
New York: World Book Inc., 1989.

\"Algae,\" Microsoft® Encarta® Online Encyclopedia 2003
http://encarta.msn.com © 1997-2003 Microsoft Corporation.

Bashour, Dr. Isam. Soil Scientist, American University of Beirut.

LeAnderson, Dr. Jim. Geologist, Biology teacher, American Community
School at Beirut.

Nimah, Dr. Musa. Irrigation engineer, American University of Beirut.

Upfold, Guy.  \"Tropical Aquatic and marginal Aquarium Plants.\" 
[http://www.aquariumplants.co.za/contact.htm](http://65.54.244.250/cgi-bin/linkrd?_lang=EN&lah=90a216c684648677285c915636d0d867&lat=1055511106&hm___action=http%3A%2F%2Fwww.aquariumplants.co.za%2Fcontact.htm). 
June 13, 2003