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Nutrients in Waterways

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Presentation on theme: "Nutrients in Waterways"— Presentation transcript:

1 Nutrients in Waterways
Nitrogen and Phosphorus Today we’ll be talking about nutrients in water. First of all, what are nutrients? (nourishing substances used for growth and metabolism of living things) We’ll concentrate on 2 common and important plant nutrients, nitrogen and phosphorus.

2 Nitrogen WHAT is it? Element # 7 in the Periodic Table
A colorless gas that makes up 78% of our atmosphere, where it exists as N2 N

3 An ingredient in Ammonia (NH3)
Nitrogen combines with Hydrogen to make Ammonia An ingredient in Nitrite (NO2) and Nitrate (NO3) Nitrogen combines with Oxygen to make Nitrates O N

4 Atmospheric nitrogen is converted to ammonia or nitrates as part of the Nitrogen Cycle.
N fixation N fixation Ammonia (NH3) Nitrogen combines with Hydrogen to make Ammonia Nitrates (NO3) Nitrogen combines with Oxygen to make Nitrates Nitrification

5 N2 from the air is converted in 3 ways
Atmospheric fixation The enormous energy of lightning breaks nitrogen molecules apart and allows nitrogen atoms to combine with oxygen forming N2O. N

6 Industrial Fixation Under high pressure and temperature and using a catalyst, atmospheric nitrogen (N2) and hydrogen are combined to form ammonia (NH3), for use as fertilizer.

7 Biological Fixation (the source of most nitrogen fixation)
Highly specialized bacteria live in the roots of legume plants (like peas and beans) or in the soil and have the ability to combine atmospheric nitrogen with hydrogen to make ammonia (NH3).

8 Nitrogen in Water: Where does it come from?
Decomposition Soil erosion Runoff of: Sewage and animal waste Fertilizers Manufacturing waste

9 Phosphorus WHAT is it? Element # 15 in the Periodic Table
A colorless, waxy solid when pure, and highly flammable, it is usually present with oxygen as phosphate (PO4) and commonly found combined with minerals in rocks O P

10 Phosphorus in Water: Where does it come from?
Weathering of rocks Soil erosion Runoff of: Sewage and animal waste Fertilizers Manufacturing waste

11 Why should we care about N and P in our water?
Nitrogen and especially phosphorus feed aquatic plants Too many nutrients can lead to excessive plant growth (eutrophication) in streams and lakes. Eutrophication can be natural or human-caused.

12 Eutrophication can cause
Increase of plants floating or in shallow water (potentially affecting recreational activities and water supplies) Increased cloudiness of water Decrease in dissolved oxygen Toxic secretions from some microorganisms Loss of sensitive species such as trout Decreased quality of drinking water (due to changes in color, taste and odor) Increased cost of water treatment

13 Science is all about solving mysteries.
Often it’s like putting together pieces of a puzzle to see the whole picture The data from Morrell Creek can help you solve mysteries related to the health of Morrell and other surface water in our watershed We can think about science as solving mysteries. Often the mystery is like a puzzle; you need to look at a number of pieces and fit them together until you begin to see what the entire picture looks like. The data you have been collecting when you sample Morrell Creek are like the pieces of a puzzle; they can help you solve mysteries related to the health of Morrell and other creeks and lakes in the Seeley area.

14 The puzzle of nutrients in Morrell Cr.
How high are they? Are they higher in some places than in others? Where are they coming from? Other questions? What kinds of questions about nutrients in Morrell Creek can you think of that might be important? They include: How high are they? Are they higher in some places than in others? Where are they coming from? How can we try to answer some of these questions?

15 A Natural Experiment Question/Hypothesis? Dependent Variable(s)?
Independent Variable(s)? How to look for patterns? Data sheet. These data show the results of the nutrient sampling at 4 different sites in Morrell Creek, with Site 1 being the most upstream site in the creek and Site 4 being the most downstream site. Samples were taken on 4 different dates at each site. (Where there is no value, the level of the nutrient was too low to be detected by the test used.) Can you think of a potentially important question you can address with these data? We can think of this as a “natural experiment”—one where we collect data from different conditions (locations) in the environment rather than creating those different conditions ourselves. 1. Can you ask a question (or state a hypothesis) for this experiment? In this experiment, what would be the independent variable(s) and what would be the dependent variable(s)? What type(s) of graphs would you use to look for patterns in these data that might help answer the question? You can create a series of graphs using Excel to answer these questions.

16 To create a bar chart of N levels at different sites on 3/4/2013:
First Insert a column chart Now click on Select Data from the chart toolbar. A new dialogue window will open. Click Add button in dialogue box Select data

17 The example graph should look something like this. What do you notice?

18 Describe any patterns you see for each of the nutrients at the different sites and at different dates. What do these patterns suggest, if anything? What further questions do you have about nutrients in Morrell Creek after looking at your graphs? Except for orthophosphate on March 4, Site 2 is always substantially higher than the other sites. This suggests a source of nutrients entering the creek near this site. Nutrient levels at Site 4 are almost always higher than Site 3, the next lowest site. This suggests additional nutrients entering the creek somewhere between Site 3 (the high school) and the highway. Where are these nutrients coming from?

19 3 Where might nutrients be entering Morrell Creek between the High School (Site 3) and Highway 83 (Site 4)? Generally, can we expect nutrient levels to be the sum of those of all the contributing tributaries? Or might there be other sources too? One way to estimate what levels of nutrients you would expect to find at a certain point in a stream is to calculate the amounts each tributary above that point contributes. 4

20 3 4 Mountain Blind Cyn Trail
For lower Morrell Creek, this would include Trail, Blind Canyon, Mountain, Swamp and Drew Creeks. Data on N levels in all of these streams except Swamp and Drew have been collected on or near three of the dates for which we have the Morrell Creek data. Sampling sites are shown with red arrows. We can use this information as a puzzle piece to see if these tributaries are where most of the N in lower Morrell is entering. 4

21 .= well site and associated septic

22 What other kind of information would you need to know, in addition to the amount of N per liter of water, to calculate how much N that stream is contributing to the system? Because different tributaries are different sizes, we need to take that into consideration as well, weighting each amount of N per liter by how much water is in the stream. In other words, if a tiny stream has a pretty high concentration of N, it’s not going to add the same amount as a larger stream with the same concentration of N, just because it’s only adding a small proportion of the overall amount of water. We can use the estimated mean flow and N concentrations in samples from each stream last spring to see what we might expect if N levels in Morrell Creek at the highway was simply the average of all its tributaries above lower Trail Creek. Then we can compare that to what was actually collected at the lower site (#4).

23 ___________________________________________________________________
((Morrell N*Flow) + (Trail N*Flow) + (Mountain N*Flow) + (Blind Canyon N*Flow)) ___________________________________________________________________ (Morrell Flow + Mountain Flow + Blind Canyon Flow) =((B3*C3)+(D3*E3)+(F3*G3)+(H3*I3))/(C3+E3+G3+I3) We can use the estimated mean flow and N concentrations in samples from each stream last spring to see what we might expect if N levels in Morrell Creek at the highway was simply the average of all its tributaries above lower Trail Creek. Then we can compare that to what was actually collected at the lower site (#4). (Since we do not have N levels for Swamp Creek, at this point we can assume it would be equal to the average of all other streams unless we have any reason to think otherwise.) In the Excel file, click on the tab at the bottom left named Weighted Means. The data sheet labeled Weighted Means should look like this when they start. They’ll need to use this formula to calculate weighted means 3. Their formula in Excel for the first weighted mean should look like this 4. Their completed table should look like this. What did you find? Are the observed samples lower or higher than expected? What do you think this means? (There is likely some source of additional nutrients below these upper sampling sites.) What additional questions does this information bring up? Do you have any suggestions for future sampling?

24 Are any of these variables correlated?
Flow Turbidity TSS (total suspended solids) Total P Total N NO2+NO3 Do students understand what is meant by a correlation between two things? If a change in one variable allows us to predict how the other will change, there is a correlation. It can be positive or negative. How can you look for correlations? A scatterplot shows how pairs of data points vary in relation to one another. For example, when flow is higher, is turbidity also higher? Let’s plot that and see! What kind of graph would you use to find out?

25 To create a scatterplot, under the Insert tab, select the Scatter with only Markers option under the Scatter chart drop-down menu. Click on Select Data to open the dialogue box. As before, use the Add button to create a title for your graph and to select the x-axis and y-axis data. In this case, you’ll select the flow (Q) values for the X values and the Turbidity values for the Y values.

26 Your graph should look like this
Your graph should look like this. How would you describe the relationship, if any, between the 2 data sets? Does turbidity seem to increase when flow is higher? Or decrease? Or stay the same? It appears there is some trend for turbidity to be higher when flow is higher, although it’s definitely not a totally reliable relationship. Besides using our eyes to estimate, we can also create a trendline and calculate the relationship mathematically with a regression equation. Click on the Trendline box under the Chart Layout tab. Select More Trendline Options at the bottom. In the window, select Linear trend type and check the Display Equation and Display R-squared value boxes at the bottom, then click Close. You should see the trendline and equations on your chart. The regression equation shows you how to find a y-value based on the x value. The R-squared value tells you how strong the correlation is. This value can range between 0 and 1, with zero as no correlation and 1 as a perfect correlation (all the points would fall directly in a straight line). Using this graph you’ve created, what would you predict the Turbidity to be at a flow of 200 cfs? How confident are you in that prediction based on the strength of the correlation (the R-squared value)? (y= Since the R-squared is fairly high, you could be pretty confident it will be close to that number.) Now create some more scatterplots to look for relationships between other pairs of variables.

27 What do you find? You should have created at least some of these graphs. What do they tell you? Which variables are strongly correlated and which are weakly correlated or don’t seem to have any relationship? Does this give you any ideas about future water quality monitoring in Morrell Creek? Summarize your findings about nutrients in Morrell Creek and propose a 10-year monitoring plan for Morrell Creek.

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