
In the initial data collected,
there was no significant difference in temperature and pH of the selected
sites. The pH was in a range of 6.1 to 7.3, and temperature was noted
as 24.7 - 29.3oC. Tests on nitrate and phosphate
levels indicated little or no presence. However, the data indicated that
with very low levels of nitrate and/or phosphate, duckweed was to prone
to growth. Areas with no nitrate or phosphate exhibited no duckweed growth.
Research
indicated that the optimum temperature and pH range for duckweed growth
is 6 - 30oC and 6.5 - 7.5, respectively. All of the
waters tested exhibited these optimums, yet they
did not share the same degree of duckweed growth. The only significant
differences occurred in the presence of nitrate and phosphate in the samples.
Only in samples which included nitrates and/or phosphates was duckweed
present implying that duckweed growth is controlled by the level of nitrate
and/or phosphate present.
To further test this theory, a controlled experiment monitoring pH, temperature, and nitrate levels was performed. The materials, procedure, and data from this experimentation can be found at Duckweed Population Lab. This data indicated that duckweed grows in the presence of low levels of nitrate. Tests on pH indicated that with large growths of duckweed, pH was more basic and in extremely high nitrate concentration, duckweed showed impaired growth and an acidic pH. Results of this lab indicated that duckweed growth was related to nitrate concentration.
A second set of data was taken at the original sites to further confirm the
correlation between duckweed growth and nutrient concentration ( nitrate and
phosphate levels). Surprisingly, areas which had previously shown no or little
duckweed growth, exhibited large duckweed blooms. Testing of pH and temperature
indicated ranges of 6.5 - 7.5 and 25 - 30oC, respectively.
These measurements very closely modeled those taken initially at the same sites.
However, nitrate concentrations at sampling sites were not the same. Every site
indicated the presence of nitrate along with duckweed growth. This supported
the theory that the presence of nitrate was influencing duckweed growth.
| PROPOSAL | CONTENT STANDARDS | RESOURCES |
| OUR DATA | INPUT YOUR DATA | MODELING |
| TEACHER ACTIVITIES | DATA ANALYSIS | HOME |