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Lessons 2: How Do Phosphate Levels Change During the Year?

Many fertilizers and cleaning products contain phosphates. Runoff from rainwater often carries these phosphates into water sources, such as lakes and ponds. How do you think the time of year affects the concentration of phosphates in ground water?

Doing the science

  1. Start the Water Quality Simulation by clicking on the "Sim" tab.
  2. Click on the "Zoom" icon.
  3. Click on the "Oliphant" location.
  4. Next, click on the "Phosphates" icon.
  5. Move the cursor to a position on Bailey’s Brook in Oliphant and click on the water.
  6. Note and record in Table 1 below the month and Phosphates concentration displayed in the popup box.
  7. Click the forward arrow next to the month "September" at the top, middle of the screen.
  8. Click on the "x" (close icon) at the top right-hand corner of the "Phosphates" pop-up box in the middle of the screen.
  9. Repeat steps 5 – 8 until you have collected phosphate data until the month of June.

Table 1.

Month

Phosphates (mg/L)

Month

Phosphates (mg/L)

September

March

October

April

November

May

December

June

January

July

February

August

Do You Understand?

  1. During which month was the phosphate level the highest?


  2. During which month was the phosphate level the lowest?


  3. During which season did the phosphate level change the most? Propose an explanation as to why this season produced the largest change in concentration of phosphates in water.


  4. Did the phosphate level change in a consistent pattern, or were the changes less ordered? Please explain your answer.