Using an Inductively Coupled Plasma Mass Spectrometer to Teach about Water Chemistry

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Carey Gazis Central Washington University
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This is a partially developed activity description. It is included in the collection because it contains ideas useful for teaching even though it is incomplete.

We are using data acquired with an ICP-MS to teach students about water chemistry at a variety of levels, ranging from high school students to upper level college students. Students are curious and enthusiastic to analyze samples that they choose and collect.
GSA Poster (PowerPoint 12.5MB Nov3 03)

Learning Goals

Content/Concepts:

Higher Order Thinking Skills:

articulating research questions, designing sampling stategies, drawing conclusions from data

Other Skills:

clean water sampling techniques, laboratory safety practice, ICP-MS operation, spreadsheet data management, graphing data, report writing

Context

Instructional Level:

High school (9-12), undergraduate entry level, undergraduate major, graduate student, individual research

Skills Needed:

Need exposure to basic water chemistry, use of spreadsheets

Role of Activity in a Course:

Situation in course varies. For example at the introductory college level, it is incorporated into class discussions and a homework exercise. In an upper-level Environmental Geochemistry course, it is a central class project that students work on in laboratory throughout the term.

Data, Tools and Logistics

Required Tools:

Inductively Coupled Plasma Mass Spectrometer (ICP-MS) -- requires specialized training to tune, calibrate, and maintain. Some aspects of operation can be done by students
Excel or other spreadsheet program

Logistical Challenges:

For class projects, students need to get data within the first few weeks of a 10-week term so that they have enough time to process and interpret data.
Students need a lot of guidance in generating graphs (deciding data to plot and the type of graph to make).
There is a wide range in students' proficiency with spreadsheet programs.
It is hard to find time for instrument maintenance and trouble-shooting.

Evaluation

Evaluation Goals:

Can students describe natural and anthropogenic controls water chemistry (e.g. chemical weathering, household plumbing, etc.)? Do students know how to process and analyze a large geochemical data set?

Evaluation Techniques:

To assess student learning, we have used a variety of methods including poster presentations, directed questions on homeworks and exams, and written research reports. The written research reports provide the most thorough assessment of student learning.

Description

An inductively coupled plasma mass spectrometer (ICP-MS) provides a rapid means of determining concentrations of multiple trace elements in waters. We are using data acquired with an ICP-MS to teach students about water chemistry at a variety levels, ranging from high school students to upper level college students. At a given level, the choice of datasets and expectations for processing and rendering data are adjusted depending on the background of the students and the time allocated for the project or assignment. In addition, the extent to which students are involved in running the ICP-MS varied; upper-level students were involved in most aspects of instrument operation while introductory-level students were not involved in lab work or ICP-MS operation.

Three examples follow:

STEP Summer Science Institute -- In this summer science camp, groups of three high school juniors conducted week-long research projects studying the chemistry of bottled drinking water and local surface waters. Students did web research on water chemistry and sources of bottled drinking water, conducted taste tests on bottled waters, and collected surface waters. Students assisted in all aspects of sample preparation and ICP-MS analysis. The instructor assisted students in organizing and graphing data and in interpreting their results. The week culminated in a poster presentation by students.

Introduction to Environmental Geology -- In this General Education course, students studied the chemistry of drinking water from throughout Washington state. Students first researched the sources of the tap water in their homes and their parents' homes. As a class, they chose locations around Washington state for sampling. The instructor analyzed the samples and prepared some of the data (5 elements) in a table and graphs. These results were given to the students as part of a homework assignment in which they were asked specific questions about the data.

Environmental Geochemistry -- In this upper-level course, seniors and M.S. students conducted a term-long class project on the chemistry of stream waters in the upper Yakima River drainage basin. In this project, students researched the local geology and the history of land use in the area. They then formulated questions and hypotheses that might be addressed with trace element data and designed sampling strategies. Students took the lead in every aspect of sampling, ICP-MS standardization and analysis, and data reduction. This included examining the data quality based on calibration curves, reproducibility, and quality assurance standards. They then selected data to address their questions/hypotheses and prepared tables and graphs. Finally students wrote individual reports presenting their objectives, methodology, results, interpretations, and suggestions for future work.