Arsenic on Main St., Unity ME
This activity has benefited from input from faculty educators beyond the author through a review and suggestion process. This review took place as a part of a faculty professional development workshop where groups of faculty reviewed each others' activities and offered feedback and ideas for improvements. To learn more about the process On the Cutting Edge uses for activity review, see http://serc.carleton.edu/NAGTWorkshops/review.html.
This page first made public: Mar 17, 2010
The ultimate plan is organizing a "Water Quality Fair" for residents of the Unity, ME area (rural farming region). Conceptually, students would analyze water samples brought into the community center (although we might end up having to use the chem lab) for common water quality issues (hardness, iron, arsenic, sulfur, and pesticides). At this fair, there will be displays by local certified water labs, water remediation options, and some interesting water activities. I hope to do this in Spring 2011.
As a pilot project, students taking analytical chemistry will analyze water samples contributed by employees of Unity College to determine the arsenic concentration and hardness during the last 2 weeks of April, 2010.
In every case, various data about the water source will be recorded to begin assembling a water quality data base for this part of the state. Products may include student-designed brochures about water quality, lessons for K12 students developed by pre-service teachers, any other good ideas students come up with. This project is expected to "feed" student/faculty research including undergraduate theses, a publishable body of scientific work, and possibly samples sites for seasonal or long term sampling.
Skills and concepts that students must have mastered
- Careful performance of lab work
- Use of titrations (hardness), spectrophotometers (arsenic, iron), and Chromatography (pesticide)
- Arsenic analysis will be done with an Arsenator (trademark of Wagtech International) which is used extensively by UNICEF in Bangladesh
How the activity is situated in the course
Content/concepts goals for this activity
Goals vary depending on phase and with which course this project will be implemented.
Phase 1: According to the Unity College catalog:
"CH 2334: Analytical Chemistry provides an introduction to the separation and quantitative estimation of organic and inorganic materials. Class work will stress stoichiometry and statistical analysis in analytical chemistry, and well as description and theory of analytical techniques. Laboratory will include a variety of titrimetric methods, some optical methods, and separation by chromatographic techniques."
Therefore the content goals include mastery of titration, spectrophotometric, chromatographic and other lab techniques.
Higher order thinking skills goals for this activity
As a class service -
- analysis of lab skills and potential errors.
- Need to build a database (even if only in Excel)
- As a further research project - map making, statistical evaluation of data sets, 3D imaging of aquifer chemistry
- Trend analysis
Other skills goals for this activity
- Scientific report writing
- Oral/poster presentations
- Literature research skills
- QA/QC - to validate the method (an Arsenator is a hand-held spectrophotometer said to be good to 10% at concentrations as low as 5 ppb).
- Event organization and planning
- Statistical analysis - mean, standard deviation, F and t tests, linear regression
- Database population (even if only in Excel, which is not a database)
Description of the activity/assignment
Class description Analytical Chemistry syllabus (Microsoft Word 2007 (.docx) 42kB Feb8 10)
Spring 2010 - Analytical Chemistry students implement the pilot project after learning to use the analytical equipment in a "standard" course context.
Pilot Project - As a service to Unity College employees, students will analyze water samples brought in by faculty and staff using techniques learned during the semester. Students will collaborate to draft a letter describing the water quality (in terms of the measured parameters) including an recommendation that the water be analyzed at a certified laboratory. Student assessment of the project will be used to modify the database, suggest activities for the full blown event planned for the next year. Based on this work, I will ask a local NGO to "request" a similar event be held in town. As an alternate to a final exam, students will present the results of this work at the Unity College Student Conference during Finals week.
Summer 2010 - I have applied for a faculty research grant to work with a student and examine water quality "downtown" (Unity has a total population of about 1500 residents).
2010-2011 - There are at least 2 possibilities: either a lab section of General Chemistry 2 or an upper-level topics class on Arsenic (my preference) will undertake planning for the "Water Days" event during Spring 2011. Projects on which students could work will include informational brochures, posters, and K12 lessons.
The Water Days event will include invitations to local analytical chemical labs and water conditioning companies to set up information displays. The data solicited from those who submit samples will include: contact information, well depth, age, existing water conditioning capability, any current complaints.
In 1995, Caswell, Eichler & Hill, Inc. evaluated the "current state of the groundwater resources" in the downtown Unity, ME area for the Town of Unity (1). Analysis of the data available from 76 wells and springs in 3 aquifers (esker, marine sand, and bedrock) found 11 wells with arsenic concentrations ranging from 0.001 to 0.200 mg/L. Other water quality issues, notably hardness (22 wells), elevated iron concentrations (20 wells), and bacterial contamination (8 wells) were noted. This report seems to have generated little further investigation. Leaching of arsenic in aquifers from meta-sedimentary bedrock high in sulfides is well documented in Central Maine (7), though arsenic leached from unconsolidated aquifers also exists (8, for example). Arsenic in Eastern New England groundwater has been weakly correlated to elevated pH (8), which plausibly explains dissolved As IV, but less so As III, which is often associated with highly reduced conditions.
The health hazards of arsenic are now well-known. Chronic exposure to low levels of arsenic in drinking water has been shown to cause multiple cancers, as well pigment changes and thickening of the skin on hands and feet (palmoplantar hyperkeratosis) (2). Chronic ingestion has also been linked to skin lesions, liver disease, cardiovascular disease, and a decrease in production of red and white blood cells due to bone marrow depression (2). Based on personal discussions with state officials, the health hazard most of concern in Maine is bladder cancer.
Arsenic in ground water is an issue of national and international concern, and of particular importance in Maine, which has naturally occurring arsenic in groundwater and well water (3, 4). Currently the National Institute of Environmental Health Sciences is funding a multilevel investigation of arsenic toxicity, mobilization and mitigation, including characterization of failed arsenic treatment systems in Central Maine (5).
This project seeks to answer the following questions: Does water quality on Main St in Unity depend on the aquifer in which a resident's well is completed? A statistically sufficient number of wells in each aquifer will be analyzed for "normal" water quality parameters (pH, alkalinity, hardness, phosphate, chloride for example) and for arsenic.
While this project does not focus on the health effects of arsenic, those are important considerations in the motivation of undergraduate students. The immediacy of working on the drinking water many students consume will also motivate undergraduate researchers as well as educate students and other residents about home water treatment systems.
- Caswell, Eichler, & Hill, 1995. The Current State of Groundwater Resources, Unity, ME. Report to the Town of Unity.
- The Department of Health and Human Services: Agency for Toxic Substances and Disease Registry has a Arsenic Toxicological Profile
- Maine Geological Survey, 2005
- Weldon, J.M. and MacRae, J. D. 2006, Correlations between arsenic in Maine groundwater and microbial populations as determined by fluorescence in situ hybridization. Chemosphere, Vol 63, N 3, 440-448
- National Institute of Environmental Health Sciences (NIEHS) Superfund basic research program.
- Dahr et al., 2004, A rapid colorimetric method for measuring arsenic concentrations in ground water, Analytica Chimica Acta, 526, 203-209.
- Welch, A.H., Westjohn, D.B., Helsel, D.R., and Wanty, R.B., 2000, Arsenic in ground water of the United States– occurrence and geochemistry: Ground Water v.38 no.4, p.589-604.
- Ayotte, J. D., Montgomery, D. L., Flanagan, S. M., and Robinson, K. W. 2003. Arsenic in groundwater in Eastern New England: occurrence, controls, and human health implications. Eviron. Sci. Technol. Vol 37: 2075-2083.
Determining whether students have met the goals
- Informal assessment during lab
- Lab notebook reviews sticky labels for notebook evaluation (Microsoft Word 38kB Feb9 10)
- Written and oral reports
Download teaching materials and tips
Introduction to Spectrophotometers (Microsoft Word 29kB Feb9 10)
Instructors Notes: Here is an annotated syllabus with rubrics (Microsoft Word 2007 (.docx) 42kB Feb8 10) for lab notebook assessment and formal lab reports.