Integrating a portable x-ray fluorescence (PXRF) instrument into undergraduate ecology, chemistry, and anthropology courses

Background/Question/Methods

We use a portable X-ray fluorescence (PXRF) instrument to provide authentic research activities in lower and upper division courses in ecology, archeology, chemistry, and earth sciences.  In doing so we are exploring methods to merge (not separate) “teaching” from “research”; and to develop models that feed into existing undergraduate courses.  Combining PXRF techniques with inquiry-based laboratory activities encourages students to solve real-world problems and engages them in multidisciplinary research.  Students in General Ecology built on a 4-week lab based on the classic decomposition study (Melillo  et al. 1982) presented as a case study in Molles textbook (4e 2008).  That lab was expanded by asking the students to measure leaf tissue K and Ca, from pre- and post-decomposition tissues (collected on-campus) from the same five tree species used in the case study. Because Ca and K measurements were not published in the original study, students began by searching the primary literature for leaf tissue Ca and K changes associated with decomposition with the five tree species.  Using those findings, they made predictions about the amount and direction of change.  Using the PXRF they compared their findings with their predictions as well the patterns and trends that were identified from the literature.

Results/Conclusions

Students in Archaeology, for example, completed preliminary geosourcing of nine obsidian artifacts.  Their reports have been provided for use in a Master's thesis on trade and migration in the Arkansas River Basin.  General Ecology students measured successfully Ca and K in pre- and post-decomposition leaf tissues.  Some findings from assessments are: 1) excitement over instrument because it is very user friendly and students feel confident in operation,  2) non-destructive nature of instrument  and rapid sample preparation time,  3) ease of PXRF operation - students/faculty are trained in less than an hour, and,  4) portability - small size and weight allows for great scope in field work.  Ultimately, the 37 students in 2008 General Ecology ranked the decomposition lab highest among all the labs in the course.  This is in contrast to previous years when students ranked decomposition last because of what they identified as ‘excessive calculations to determine mass loss rates’.  The single best insight from integrating this instrument into a broad array of undergraduate lab courses is that the PXRF allows faculty to promote direct, discovery-based learning where students can explore a question as it unfolds, using real-time readings from the instrument to guide further questioning.