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CEES Visits High School STEM Clubs

"Sustainable Agriculture in an Urban Environment" Debuts in Lawrence


A room full of high school students . . . . bags of soil waiting patiently by an X-ray Fluorescence analyzer . . . . a vermicompost bucket brim-full of red wigglers and nutrient-rich castings (aka "worm poo") . . . . time to do some science!    



                                Sam Ansaldi, CEES's Education Specialist, greets the STEM Club students.


In early March, CEES had the opportunity to present a new program - Sustainable Agriculture in an Urban Environment - to the after-school STEM clubs at Lawrence North High School and Lawrence Central High School.  The program introduced students to the constraints and benefits of growing and harvesting various food plants in an urban environment. 



                                 Sam explains vermicomposting.


The program started like many others: when initially asked a question - in this case, “Can we farm in cities?” - few, if any, of the teenagers offered up so much as a raised hand, let alone a detailed response to the query.  It was the typical resounding silence, followed by a few hesitant comments.  That was when Sam Ansaldi, CEES's Education Specialist, pulled out the big gun . . . . literally and figuratively.  While Sam did, in fact, literally reach into CEES's bin of science tech and pull out a device that resembled a cross between a Star Trek phaser (original series) and a grocery store barcode scanner - the "gun" analogy is merely figurative because the gizmo shown to the students, an X-ray Fluorescence analyzer (or XRF), is not an actual gun - though it does shoot X-rays!  Carefully, the face of the XRF was pressed against a sandwich bag filled with soil (collected from one of the local neighborhoods) and a reading was taken.  In less time than it takes to name the castaways on Gilligan's Island, the XRF had analyzed the sample's elemental composition and sent back a flurry of data detailing the heavy metal profile of the soil: mercury, arsenic, and lead levels appeared in orderly array on the screen. 



                                   CEES intern Shelby Gills displays the XRF.


In the stunned silence that followed, Sam explained to the students that they had just witnessed X-ray fluorescence analysis - a non-destructive analytical technique used to determine the elemental composition of materials.  The key thing to remember about X-rays (the students were told) is that they are very high energy.  The XRF analyzer shoots X-rays into an object, and, when those primary X-rays strike an object, some of the energy of the X-rays is transferred to the object.  The molecules of the object now have more energy than previously, and are described as being in an "excited" state.  The excited molecules release fluorescent (secondary) X-rays, which are detected by the XRF.  Each element produces a characteristic fluorescence "fingerprint" that is unique to that specific element, which is why XRF spectroscopy is an excellent technology for qualitative and quantitative analysis of material composition.  It can tell us what is present - at an elemental level - as well as how much of a given element is present.

Awed and amazed by the XRF, a device that in mere moments had produced a comprehensive profile of the soil sample, and attention now fully engaged, the students were ready for the follow-up question: “So, who wants to try next?”

Hands-on activities and the opportunity to use the tools of science, such as soil sampling with the XRF, set the tone for the program.  Students performed chemical analyses on soil samples collected from local neighborhoods, learned more about small-space alternative farming practices, and got up close and personal with the inhabitants of a nutrient-producing vermicompost system. 



                                 Shelby guides the STEM Club students through an activity.


By the end of the program, there was not a student present who didn’t have a hand raised in anticipation of answering questions and joining the conversation.  The students came to the program anticipating a (boring?) lecture about city gardens and corn crops. Instead, they got to do actual science!  Discussion and activities centered on the challenges presented by urban farming (such as heavy metal contamination of soils and growing produce in a small space) and finding solutions to those challenges.  For example, vermicomposting addresses two problems: worms fed table scraps produce nutrient-rich castings - which reduces the amount of food waste that ends up in landfills or incinerators, and the castings take the place of commercial fertilizers (which have a large carbon footprint).  The students came away from the program with greater knowledge of what urban agriculture entails, what is needed now and in the future for healthy food production, and creative land-use ideas to enhance access to fresh food for those living in areas where such produce is often scarce. 


This is the mission of the Discovering the Science of the Environment program: engaging youth in doing science, increasing awareness about environmental issues, and sharing solutions to environmental problems. 


CEES thanks the IUPUI Department of Earth Sciences for the loan of the department's XRF for this program.


Authors: Sam Ansaldi & Victoria Schmalhofer



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