Monday, November 21, 2011

Field Trip, Part 1

The fifth graders' visit to campus on Monday, November 7 was a huge success! We had a great time and our visitors did too. I'll be posting more pictures just as soon as the Rankin teachers and I have an opportunity to screen out any pictures of students who don't have a signed photo waiver, but in the mean time, I wanted to put up some pictures of my A&T students and the experiment we did with the 5th graders.

After an opening welcome at the Student Union, we had a group photo (to be posted!) and then the 5th graders went on a campus tour with 4 great Aggie Ambassadors! Then the four classrooms split into two groups and went either to lunch at the dining hall first or came to do the ELISA experiment first.

For the ELISA, our essential questions were (1) what is an ELISA, and how does it help us detect pesticides in our water? and (2) which water sources are most likely to be contaminated with pesticides, and why?

The picture in the background of our title slide shows the Graham Paddle Put-In along Hwy 54, where I obtained the Haw River water samples that my students tested (see previous post).

To begin, each laboratory group of A&T students from my class explained to their 5th grade partners how an immunoassay works. The 5th graders followed along on a worksheet.
 We had the 5th graders test 6 simulated samples representing run-off from a corn-field, water from a drinking fountain and bathroom sink, water samples from streams 1 mi or 5 mi away from the corn field, and water from the Haw River. The picture below shows Jacqui and Shaylon describing our 6 samples to the students in Ms. Weyant's class.

The 5th grade students worked in groups of 4 to test these samples using a re-purposed Simulated ELISA kit from Carolina Biological. My students helped me aliquot all the reagents from 2 kits into color-coded, labeled vials, and we used color-coded visual aids to help keep everyone caught up and on task.

The CHEM 432 students led the classroom in the activity (see Talibah below) and worked with individual groups of 5th graders.

Each group of 5th graders also had an adult partner who helped them follow the procedure. Thanks to Jazz, Justin (below), Vicki, Laurel, and Jill for coming out to A&T from Chapel Hill to help. Thanks also to Dr. Powe's 9 am chemistry class for helping with the experiments and with preparations!
During the incubation step, the 5th grade students made predictions (hypotheses) about which water samples would test positive for pesticides. Then, the CHEM 432 students (see Julalak below) helped them read out and discuss their results: a purple color indicated that pesticide was present.
More pictures to come soon!

Wednesday, October 19, 2011

Pesticide Detection Results

Last week the students turned in revised versions of their abstracts and figures from the ELISA and GC-MS analyses that we performed on a water sample from the Haw River in Alamance County. The laboratory protocol was based on an article from the Journal of Chemical Education and is available on request.

Jacqueline Meadows has agreed to let me share her abstract and figures on the blog so you can see our results. Luckily, both ELISA and GC-MS analysis indicated acceptably low levels of pesticides in the original water sample.

Pesticides are chemicals used to increase the amount of yield from crops. Though these compounds are useful in the productivity of farming, they may also have harmful implications when they run off into waterways, like lakes and rivers. The purpose of this experiment was to analyze the concentration of two pesticides, atrazine and simazine, in a water sample taken from the Haw River. The sample was tested as obtained from the river and also spiked with relatively high concentrations of atrazine and simazine. The concentrations were evaluated using ELISA and gas chromatography mass spectrometry (GC-MS). The ELISA method revealed an original sample concentration of 0.890±0.123 ppb of atrazine and a spiked sample concentration of 112±0.1 ppb of atrazine. The GC-MS, however, reported an atrazine concentration of 0.00±0.26 ppb and a simazine concentration of 1.74±0.05 ppb in the original sample, and concentrations of 73.4±0.2 ppb and 129±0.04 ppb in atrazine and simazine, respectively, for the spiked sample. The average retention time of atrazine was 12.65 minutes and that of simazine was 12.55 minutes for the GC experiment. The ELISA data was more sensitive than the GC because it was able to detect smaller amounts of the pesticide, whereas the GC method was able to quickly and efficiently separate the different pesticides for analysis.


Figure 1: ELISA data for atrazine standards.
Figure 2: Gas chromatography peak areas for given concentrations of atrazine and simazine standards.

(Abstract and Figures courtesy of Jacqueline Meadows)

Friday, October 7, 2011

First Classroom Visit!

Today the undergraduates had their first classroom visit to Rankin Elementary School here in Greensboro, NC. The visit was a huge success!

In Ms. Kanipes' classroom, Charnell and Julalak led the students in a Play-Doh ecosystem activity. Each table group of 5th graders made an ecosystem, complete with volcanos, flowers, and frogs, among other things. Then they sprinkled Kool-Aid drink mix powder on a field in the ecosystem to represent pesticide treatment. Each group "made it rain" on their ecosystem using a spray bottle of water, so that the students could see how rain water carries pesticides in run-off into rivers and streams. Fantastic demo! They also had the students do a card matching vocabulary activity.

In Ms. Crutchfield's classroom, Talibah and Jordan led the students in a role playing game about the effects of pesticides. The students were assigned roles to play: farmer, crop, pesticide, pest, weed, or "good bugs" (like ladybugs and bees). After the farmers watered the crops, the crops grew, but were attacked by pests and weeds. The pesticides were allowed to tap players on the shoulder and make them sit down, but they could also tap the ladybugs and bees! This game led to a very fruitful discussion with the students about the unintended ecological consequences of many pesticides.

In Ms. Lewis' classroom, Bridget, Ronald, and William started by showing a clip from a Captain Planet video about pesticides. Then the A&T group had each 5th grade student start with a cup of water, some of which were contaminated with "pesticide" (acid). The students used droppers to mix the water from their cups, and at the end, they used pH paper to show how contaminated water can spread through the water system without obvious changes to how the water looks. The class also played Pesticide Bingo from the EPA website.

In Ms. Weyant's classroom, Jacquie and Shaylon had the students identify objects and substances that do and do not below in the ecosystem around a river. Candy prizes resulted in lots of lively participation as the students learned about the positive and negative effects of pesticides by answering questions and doing a crossword puzzle. After the presentation, one table group of 5th graders assured me that my students had done a very good job teaching them and proved their point by highlighting all the important things they'd learned about pesticides this afternoon.

Each classroom visit closed with the announcement that the 5th graders would see the NC A&T students again in November when the Rankin elementary students visit our campus. We can't wait for the next event!