GEOFF SMITH
Environmental Chemistry in the Undergraduate Laboratory
THOMAS J. WENZEL AND RACHEL N. AUSTIN
Bringing environmental topics into undergraduate curricula connects students with complex real-world issues.
aboratory exercises tied to environmental issues are extremely useful in analytical and general chemistry courses. Why? Because without them, class experiments often have no apparent relevance to the real world, emphasizing instead classical content and laboratory skills development at the expense of conducting meaningful investigations, solving realistic problems, and promoting teamwork. Under these circumstances, students can become disengaged from the learning process. Experiments that include environmental topics enable students to see the connection between chemistry and their world and facilitate the conceptual leap from abstract scientific concepts to useful applications. Student interest is heightened as a result of including such material, and there is greater course commitment. Increasingly, instructors at universities and colleges are realizing the advantages of this powerful approach for engaging students in coursework, and many schools now integrate environmental chemistry elements into undergraduate classes and labs. The practice has become so prevalent that, since 1998, the Journal of Chemical Education has annually devoted much of its December issue to the topic. Curricular Developments in the Analytical Sciences, a recent report written by stakeholders from U.S. academia, industry, government, and professional orga-
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nizations, supports this approach and advises the academic community to develop context-based, undergraduate curricula that incorporate problem-based learning (www.chem.ukans.edu/analyt_curricular_ dev). Several of the best practices highlighted involve projects and problems having an environmental theme. The stakeholder recommendations mirror those of Shaping the Future, a 1996 National Science Foundation report that more generally examines the undergraduate science curriculum (1). Environmental investigations are also valuable because of their inherent complexity, which necessitates appropriate controls and careful design to obtain meaningful data. Unlike many traditional investigations, environmental chemistry-based projects are often characterized by an increased measure of uncertainty, that is, data may or may not readily support a hypothesis—this is a good learning experience, as such an outcome is typical of real-world studies. Environmental coursework is readily adaptable to existing curricula. Instructors can set the level of sophistication of lab work by deciding ahead of time what environmental samples and problems will be investigated. In turn, these choices dictate what analytical methods and instrumentation will be used. A further important aspect of environmental experiments is that they frequently relate to topics of community interest. Such connections heighten student awareness of the need for performing careful analyAUGUST 1, 2001 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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ses, expand opportunities for communicating results, and provide a further measure of realism.
Courses and programs Various instructional approaches incorporate environmental science into general and analytical chemistry courses. One notable example is the marine aquarium project designed by Hughes (2), in which classical analytical techniques typically included in a quantitative analysis course are used to measure important chemical species in a marine aquarium; determinations based on other instrumental methods can also be devised. Students work for a semester in teams and rotate through a series of experiments that monitor different water components. At Rutgers University in New Jersey, Herzog and co-workers revised the university’s analytical chemistry laboratories using a modification of Hughes’s approach that focuses on analyzing seawater (3)—many wet and instrumental methods are applicable for analyzing its constituents. The collaborative effort involves faculty members from the Marine and Coastal Sciences, Environmental Science, Biochemistry and Microbiology Departments, and the University’s Long-Term Ecosystem Observatory. Adaptations of this theme to freshwater systems, which are often easier to maintain in a laboratory setting, have been reported. Storer, at Southern State Community College, Hillsboro, OH, has students in the general chemistry class follow the nitrogen cycle over a 4- to 5-week period in a newly established freshwater aquarium (4). At Idaho State University in Pocatello, Houghton and Kalivas altered their sopho-
more-level quantitative analysis lab to include a project in which students examine chemical components of a cold-water trout environment (5). Classical analysis methods and near-infrared spectroscopy are used to determine the moisture and lipid content of fish. Students work in groups and take turns serving as the experiment project manager. To connect environmentally based lab experiences to community concerns, Fitch and co-workers at Loyola University of Chicago organize their instrumental analysis course around the measurement of lead (6). Students use several measurement techniques and compare the relative strengths and limitations of the methods. Subsequently, they perform lead analyses on samples of interest to a client—one class investigated whether soils in a neighborhood close to an incinerator had higher than average lead levels compared with surrounding areas. Although the assessment’s complexity prevented them from reaching a firm conclusion, the results were useful as a guide for studies the following year. At Union College in Schenectady, NY, one faculty member’s attendance at a Trout Unlimited (TU) meeting led Werner and co-workers (7) to develop a quantitative analysis project in which groups of students rotating through different sets of analyses measure several chemical constituents in local streams, using classical and instrumental methods. The results contribute to a growing database that helps TU monitor and assess stream quality. By periodically introducing new methods, new streams, different monitoring times, and longitudinal studies, the lab remains fresh for students and instructors alike.
Introductory chemistry with an environmental focus In 1998, Bates College began offering a two-semester general chemistry course that relates fundamental chemistry concepts to environmental studies and incorporates semester-long projects. Requiring such activities produces several positive outcomes, notably, that students become more engaged than they would if performing projects of weekly duration. The course fulfills the general chemistry prerequisite for all upper-level chemistry courses and satisfies the chemistry requirement for Bates’s B.S. degree. The same text is used as in other general chemistry sections; however, supplemental readings are included for the environmental components. The course is limited to 60 students. Lab sections have no more than 20 students. The knowledge skills gained ensure progress in upper-level courses in allied fields, as well as completion of senior theses. In the first-semester lab, small student groups undertake a semester-long project. The goals of last year’s project were to determine whether lead uptake increases in plants grown in soil contaminated with lead paint dust and whether lead uptake varies with the acidity of solutions used to water the plants. Relevant to the experiment, each group identifies and lists questions and variables to consider, and before beginning work, the group lists are composited. To perform the experiment, each group collects its own 328 A
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soil samples, establishes what pH and acids to use in making up simulated acid rain-watering solutions and decides on what control sample to use as a basis against which to test hypotheses. Instructors provide each group with leaded paint dust (10% lead) for preparing contaminated soil samples and concentrated acids for making needed acid and watering solutions. The groups each perform their own calculations and prepare the solutions needed for use throughout the term. Making all of the solutions teaches them general lab skills (e.g., pipetting, using volumetric glassware, cleaning, and making stoichiometric calculations) that are overlooked in many general chemistry labs, in which solutions are often just provided. Each section has one instructor and an undergraduate teaching assistant. Occasionally, students are given help in operating analytical equipment. Necessary calculations are explained and comments are provided concerning experimental design. Students also receive assistance with analytical methods, advice regarding proper handling of chemicals, and solution preparation tips. Plants are grown in a rooftop greenhouse that students can access throughout the term. About three weeks before the term ends, plants are harvested, dried, digested using a microwave apparatus, and analyzed for lead using flame atomic absorption and inductively coupled plasma-atomic emission spectroscopy.
Hope and Johnson, at Medgar Evers College in mental analysis lab and now have students conduct New York City, base labs on urban air sampling exenvironmental investigations (10) such as measuring periments to demonstrate the problem-solving naacrolein and acrylonitrile in river water to assess ture of analytical chemistry (8). Students analyze and whether a nearby manufacturing plant is releasing compare ambient and indoor air samples for volatile the material and whether its concentration is a danorganic compounds (VOCs) and particulate matter ger to nearby populations. for adsorbed nitrite and VOCs. They also compare mercury levels in households where the metal is used More courses and programs for religious purposes against those in several homes At Bates College in Lewiston, ME, a separation science where it is not used. Reporting the results of the mercourse offers a lab consisting of semester-long, smallcury measurements to participants in the study teachgroup projects (11). These involve measuring chemes students of the need to address sensitive issues icals of environmental concern, including carefully. polyaromatic hydrocarbons in wood smoke, At Emory University in Atlanta, Ram creosote, diesel exhaust, and charbroiled developed problem-based, sophomeats; VOCs in air; chloroform in drinkmore-level analysis labs that examing water; and heavy metals in sludges ine water quality issues in the from the local wastewater treatment Atlanta region (9). Students “hired” plant. Students in this year’s class by the Upper Chattahoochee will try to identify a pesticide apRiverKeeper, an environmental adplied to a rare book collection. The vocacy group, learn to identify, unaccompanying sidebar beginning derstand, and run EPA-approved on page 328A describes other envianalyses on real samples. ronmental activities at the college. Following EPA protocols requires At Northeastern University in that the students understand comBoston, Mabrouk has students in plex procedures and sometimes a quantitative analysis course asunclear instructions. Students also sess whether water quality, lead, have an opportunity to visit the and carbon monoxide home test The study teaches Georgia Environmental Protection kits are valuable safety resources students of the need Division laboratories. for consumers (12). Students Street and Sittidech, at the choose appropriate reference anto address sensitive University of Alabama–Tuscaloosa, alytical methods against which to issues carefully. revised their upper-level instrucompare the performance of the
Throughout the term, rainfall is collected on a rooftop station and analyzed for nitric and sulfuric acid using ion chromatography. This past year, the groups used watering solutions having pH values in the range 3.5–4.5 that were made up from a 50:50 mixture of nitric and sulfuric acids and water. The pH values of collected acid rain water samples had a range of about 4–4.5. Measurement of the molar concentrations of nitric and sulfuric acids in the collected rainwater revealed that the student-selected mixtures reasonably represented area acid rainfall. The complexity of this environmental system is ideal for showing how scientific investigations can lead to inconclusive results that require further experimentation. To assess outcomes, the lead analyses from each group’s plant and soil samples were compiled into a report for use by the entire class. Data interpretation was instructive. Although students hypothesized that lead solubility should increase with greater acidity and that plants might correspondingly take up more lead, the data on lead uptake as a function of pH were inconsistent with this supposition—different groups observed opposing trends for their samples or no consistent trend. The findings provided a basis for discussing project limitations, including uncontrolled variables, such as soil and plant type, number of plant
samples, available time for exploring the lead uptake behavior, and the environmental system’s complexity in general. The second-semester lab involves a marine aquarium (tank) project (3). Over three years of operation, several varieties of fish, plants, and other living organisms have been introduced to the tank. Students monitor and maintain the aquarium during the semester and prepare all test solutions, including calibration standards required for the analytical measurements. Last year, the inclusion of a new variety of fish inadvertently introduced a disease to the tank. Treatment required extensive monitoring and establishment of an isolation tank for the diseased fish. This happenstance provided students with an appreciation of the complex nature of water chemistry and natural systems, and the extent to which changing one variable can lead to a cascade of unforeseen consequences. They became more aware of the need to carefully prepare standards and samples and properly perform analyses. Carrying out these exercises gives students more confidence when performing chemical analyses related to their course and thesis work and makes them more likely to question the accuracy of their analytical data.
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home test kits, then carry out measurements and assess each kit’s value. Environmental chemistry is also incorporated into general chemistry courses and labs, including modules that are exportable to other curricula. Howe, Cizmas, and Bereman at North Carolina State University in Raleigh describe a module that shows how the concentration of phosphates in a freshwater lake is related to its eutrophication (13). The module promotes a dynamic learning experience, develops analytical and problem-solving abilities, and demonstrates how complex environmental problems can be addressed through an interdisciplinary approach. Although the material is intended primarily for discussions and lectures, a laboratory exercise using computer simulations enables students to visualize lake phosphate concentrations. O’Hara and Sanborn at Amherst College in Massachusetts and Howard at the California Institute of Technology in Pasadena, describe an introductory chemistry module (14) in which trace levels of xenoestrogenic pesticides in local drinking water are measured and their molecular shapes are compared to estrogen. To broaden the project’s scope, the class undertakes aspects of the measurements, data analysis, and final report to the town water commissioner in conjunction with a sixth grade and a high-school chemistry class. The University of California– Berkeley and Beloit College in Wisconsin are lead institutions for a multiinstitutional chemistry education initiative, the ChemLinks and ModularCHEM consortium (15). Teaching modules having environmental significance include in-class, out-of-class, and laboratory exercises. Modules involving topics of environmental significance include “What Should We Do About Global Warming?”, “Should We Build a Copper Mine?”, and “Soil Equilibria: What Happens to Acid Rain?”. Juhl, Yearsley, and Silva at Eastern Idaho Technical College in Idaho Falls describe a water quality project that samples and analyzes local river water for organic, inorganic, and fecal contaminants. It is designed for the final semester of a twoyear chemical or environmental technician associate degree program (16). Students gain experience with analytical instrumentation, EPA procedures, problem solving through interdisciplinary group interactions, and cooperating with state agencies and private organizations. The applied learning experience teaches necessary responsibilities, as well as interpersonal and organizational skills required of workplace professionals. Woosley and Butcher at Western Carolina University in Cullowhee, NC, developed experiments that analyze chemical constituents of Fraser fir, including volatiles, chlorophyll, and metals (17). Assigned work ranges from two-week exercises to semester-long projects in a senior-level instrumental analysis laboratory. Environmental learning experi330 A
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ences such as these are now part of a departmentwide theme at the university (18). Lab work emphasizes green synthesis, molecular modeling of environmentally significant compounds, a field station monitoring project at a nearby stream, and projects that analyze environmentally important chemicals. Faculty members in the chemistry department all now conduct research having an environmental component. The focus unifies their activities and provides an underlying identity. Wilson, Larive, and co-workers at the University of Kansas in Lawrence revised both the general and analytical chemistry laboratories around an environmental theme (19, 20). In the introductory course, students select a sample and choose analysis methods for a lengthy water quality experiment. This water quality assessment theme continues into the firstsemester analytical lab where more advanced analyses are performed. For example, atrazine, a common corn-belt herbicide, is measured in surface and drinking water using gas chromatography/mass spectrometry. In the second-semester analytical lab, students are each given an extended problem, several of which are environmental in scope. One example project involves analyzing lead and cadmium in soil samples taken from a Superfund site. In some projects, students are linked with an external industry or a government consultant who is available to give them advice.
Meeting tomorrow’s needs Environmental projects are well suited to student group-learning experiences. The approach fosters cooperative teamwork and promotes improved oral and written communication skills. Such projects demonstrate the interdisciplinary nature of scientific investigations and the importance of science to society. Connecting projects to community organizations and concerns further enhances student involvement and challenges them to do their best. One area poised for curricular innovation and inclusion in the undergraduate organic chemistry laboratory is environmentally benign syntheses. Reed and Hutchison of the University of Oregon–Eugene describe what is possibly the first published green experiment (and part of a broader green curriculum) for use in the organic teaching laboratory (21). Also noteworthy, the American Chemical Society, in partnership with the U.S. EPA, is developing and disseminating educational materials for green chemistry initiatives (www.acs.org/education/greenchem/ acsproject.html). U.S. Presidential Green Chemistry Challenge Award recipient Terry Collins argues that green and sustainable chemistry principles must become an integral part of chemical education and practice (22). A positive result of further development of green organic labs, and beyond that, the integration of environmental topics throughout the undergraduate chemistry curriculum, is that it will improve student
education and better prepare them to practice more environmentally sustainable chemistry.
Acknowledgments Support of the National Science Foundation for purchase of equipment through the Course, Curriculum, and Laboratory Improvement Program (DUE9950314) and Bates College for Faculty Development and Otis Grants to support development of the introductory course is gratefully acknowledged. We deeply appreciate the assistance of Lorna Clark, Michael Danahy, Peter Schlax, Gary Starzynski, Mary Brushwein, and Kathy Covert in developing the associated laboratory coursework.
References (1) Shaping the Future: New Expectations for Undergraduate Education in Science, Mathematics, Engineering, and Technology; National Science Foundation: Washington, DC, 1996. (2) Hughes, K. D. Anal. Chem. 1993, 65, 883A–889A. (3) Herzog, G.; Chase, Jr., T.; Reinfelder, J.; Sherrell, R.; Schofield, O. 27th Annual Conference of the Federation of Analytical Chemistry and Spectroscopy Societies, Sept. 24–28, 2000, Abstract 145, FACSS National Office: Santa Fe, NM. (4) Storer, D. 211th National American Chemical Society Meeting (ACS), New Orleans, March 1996, Abstract 650; ACS: Washington, DC, 1996. (5) Houghton, T. P.; Kalivas, J. H. J. Chem. Educ. 2000, 77, 1314–1318. (6) Fitch, A.; Wang, Y.; Mellican, S.; Macha, S. Anal. Chem. 1996, 68, 727A–731A.
(7) Werner, T. C.; Tobiessen, P. L.; Lou, K. A. Anal. Chem., 2000, 73, 84A–87A. (8) Hope, W. W.; Johnson, L. P. Anal. Chem. 2000, 72, 460A–467A. (9) Ram, P. J. Chem. Educ. 1999, 76, 1122–1126. (10) Street, S. C.; Sittidech, M., 27th Annual Conference of the Federation of Analytical Chemistry and Spectroscopy Societies, Sept. 24–28, 2000, Abstract 146, FACSS National Office: Santa Fe, NM. (11) Wenzel, T. J. Anal. Chem. 1995, 67, 470A–475A. (12) Mabrouk, P. A. Analytical Chemistry Lab Manual, 7th Ed., Denton–RonJon Publishing: Denton, TX, 1993. (13) Howe, A. C.; Cizmas, L.; Bereman, R. J. Chem. Educ. 1999, 76, 924–926. (14) O’Hara, P. B.; Sanborn, J. A.; Howard, M. J. Chem. Educ. 1999, 76, 1673–1677. (15) Anthony, S.; Mernitz, H.; Spencer, B.; Gutwill, J.; Kegley, S.; Molinaro, M. J. Chem. Educ. 1998, 75, 322–324. (16) Juhl, L.; Yearsley, K.; Silva, A. J. J. Chem. Educ. 1997, 74, 1431–1433. (17) Woosley, R. S.; Butcher, D. J. J. Chem. Educ. 1998, 75, 1592–1594. (18) Atterholt, C.; Butcher, D. J.; Bacon, J. R.; Kwochka, W. R.; Woosley, R. J. Chem. Educ. 2000, 77, 1550–1551. (19) Wilson, G. S.; Anderson, M. R.; Lunte, C. E. Anal. Chem. 1999, 71, 677A–681A. (20) Larive, C., 26th Annual Conference of the Federation of Analytical Chemistry and Spectroscopy Societies, Oct. 24–29, 1999, Abstract 221, FACSS National Office, Santa Fe, NM. (21) Reed, S. M.; Hutchison, J. E. J. Chem. Educ. 2000, 77, 1627–1628. (22) Collins, T. Science 2001, 291, 48–49.
Thomas J. Wenzel is the Charles A. Dana Professor and Rachel N. Austin is an assistant professor in the Department of Chemistry, Bates College, Lewiston, ME.
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