Loboviz Comparing the Effects of Precipitation on Nitrate Levels in the Old Salinas River Channel

Loboviz Introduction: The LOBO observatory L3 buoy has collected data showing changed nitrate levels in the Old Salinas River Channel. Normal oceanic nitrate levels are 10 µm (micromol). Nitrate levels in the Old Salinas River Channel have reached 2000 µm. Fluctuations in nitrate have been linked to tidal changes and storm events. Goal: Students will compare and analyze nitrate concentrations and precipitation levels. Question: How will an increase in precipitation effect nitrate levels?

Map above from: CIMIS /cimis/infoStnMapSanJoaqui n.jsp Map below from: LOBOVIZ Network ork.htm#LOBOmap

Loboviz Materials: computer, access to: Loboviz realtime data set page CIMIS weather data page

Loboviz Procedure: Ask students to develop their own hypothesis based on the introduction and question. (Example for the Teacher: An increase in rainfall will increase runoff and fresh water influx into the Old Salinas River Channel and decrease nitrate level.) DATA Procedure 1)Open the Loboviz data access page:

Loboviz Procedure continued: Select the following: 2) Station: L03SURF.TXT 3) X Variable: Date 4) Y Variables: Nitrate 5) Autoscale select: On 6) Quality Select: All Data 7) YStack Select: Off 8) Time Select: All Data 9) Start Date 02/01/ ) End Date 03/31/ ) Output: Plot

Loboviz Data from Loboviz, adapted in Excel

Loboviz Data from CIMIS, adapted in Excel

Loboviz Student Activity:  Describe the patterns you see in the nitrate graph and precipitation graph.  How did the patterns differ or agree with your hypothesis?  The L3 buoy is positioned in the center of the Old Salinas River Channel. If another buoy was placed near the edge of the riverbank, would there be a change in the data? If so, how?

Loboviz Results: Increased rainfall correlated to decreased nitrate levels from 02/01/2005 to 03/31/2005. (See 3/15/2005 and 3/22/2005.) Teacher Discussion hints: Higher rainfall levels could dilute nitrate levels in the Old Salinas River Channel. However, nitrate levels tend to be more concentrated at the bend or edge of a river. Therefore, buoy placement might effect nitrate data readings. Castroville (the site of the precipitation data) has significant artichoke farming. MBARI hopes to share this data with local farmers to increase their efficacy of fertilizers (without wasting them) and lower nitrate levels.

LOBO L3 Buoy

Loboviz Extensions:  How can we determine where the nitrates are coming from?  Would testing the farmers’ wells be helpful?  If nitrate runoff was minimized what would be the economic impact on farmers and fertilizer distributors?  Aside from farming, what are some other sources of nitrates? (Teacher hint: look up maps of area and look for other sources).  Examine LOBOVIZ again, examine data for dissolved oxygen and nitrate levels to explore the effects of eutrophication. (Teacher hint: DO levels will be lower with high eutrophication.)

Web resources Irrigation Scheduling: What’s in Your Watershed (Bridge Data Tip)

Notes on Loboviz:  Menu choices should correspond automatically to data available at the station. Ex.: types of chemical parameters, date  Need metadata explanation. Ex.:Quality Select: What’s the different in the data types?  Need to be able to manipulate output in Text file format. Ex. Each day has at least 6 data point. It would be nice to be able to average these to get 1 data value.  In general, the interface needs to be modified to be more teacher and student friendly. GROUP CONTRIBUTORS: Stephen Coleman, Susanna Musick, Julie Ribar, Eric Simms