A Research Study of Tropospheric Ozone and ... - ACS Publications

In the Classroom

A Research Study of Tropospheric Ozone and Meteorological Parameters To Introduce High School Students to Scientific Procedures Yolanda Díaz-de-Mera, Alberto Notario, and Alfonso Aranda* Department of Physical Chemistry, University of Castilla-La Mancha, Ciudad Real, Spain *[email protected] Antonio Adame Jose Department of Applied Physics, University of Huelva, Huelva, Spain Alfonso Parra and Eugenio Romero IES Ribera del Bullaque, Porzuna, Ciudad Real, Spain ~ oz s Parra and Fernando Mun Jesu IES Alonso Quijano, Argamasilla de Calatrava, Ciudad Real, Spain

One of the main concerns in all levels of education is students' lack of motivation. Over the last two decades, a decrease in the number of students starting university studies in science, such as chemistry, and an increase in students enrolling in technical studies has been observed. One of the reasons for the lack of interest in science may be the teaching procedures. Students are usually told about science instead of being asked to do science. Collaboration between universities and high schools is usually restricted to theoretical or demonstrative courses in one or a few sessions. Most often, students have their first contact with the university when they start their university studies. However, over the last 10 years, universities have strengthened their recruiting strategies to attract good students. Collaboration with high school teachers and the participation of students in university research projects is an effective tool that allows universities to display the qualities of their institutions. Thus, besides facilitating the transition from high school to university, such projects may be useful as an interface between high school and the university. Recently, regional and state administrations with jurisdiction over educational issues are becoming aware of the benefits of such interfaces and are promoting cooperation between high school teachers and university lecturers in the fields of innovation and research (1). Scientific research is generally considered not to be an easily feasible goal for high school students owing to the conceptual difficulty of research studies and the lack of experimental facilities. Thus, students may perceive chemistry, physics, environmental science, and natural science as theoretical subjects that they should believe in without any interaction. However, there are many everyday natural events that are accessible to everyone and may be studied or evaluated from a scientific point of view. In some cases, the required research facilities are simple and relatively accessible at a low cost. Even in those cases, previous experience in research topics and in the management of the equipment is necessary. Within this context, collaboration with university research groups is helpful, and even necessary, in the design, startup of the experiments, and analysis of the results. The high school 392

Journal of Chemical Education

_

_

teachers have experience with the students and, thus, know how the experiments can enhance their interest in the subjects and know ways to improve teaching-learning processes. With this perspective, a research project was developed with two main components: research in innovative teaching methods for high school and a research study in environmental issues. The experiment involved high school students in the measurement and analysis of the short- and long-term profiles of tropospheric ozone and meteorological parameters. As shown in the literature (2), tropospheric ozone formation results from NO2 photolysis. Thus, a chemical equilibrium between NO, NO2, and O3 is rapidly established for given solar radiation conditions: NO þ O3 f NO2 þ O2 NO2 þ hν f NO þ Oð3 PÞ Oð3 PÞ þ O2 f O3

λ < 424 nm

ð1Þ ð2Þ ð3Þ

Taking into account that NO is emitted from the earth's surface (mainly from anthropogenic sources), whereas NO2 in the lower atmosphere comes almost exclusively from reaction 1, a decrease in O3 and NO levels is expected at night because reaction 2 does not take place. On the other hand, under sunlight conditions, the chemical equilibrium increases the level of O3 and the NO/ NO2 ratio. A previous article on ozone in this Journal (2) describes an experiment with upper-level university students and another article describes experiments involving high school students in the study of indoor pollution (3). The educational objectives of this project were as follows: • To involve high school students in the research project to motivate their interest in the field of science. • To experiment on new teaching methods to complement lecture-based teaching. • To develop an interface between high school and the university, which may serve as a motivation to initiate university studies and soften the transition. • To contribute to the ongoing education of high school teachers.

_

Vol. 88 No. 4 April 2011 pubs.acs.org/jchemeduc r 2011 American Chemical Society and Division of Chemical Education, Inc. 10.1021/ed1002515 Published on Web 02/04/2011

In the Classroom

To achieve these objectives, we encouraged the active participation of students in activities that required the use of scientific equipment and methodologies, in an attempt to enable them to do science, by contrast with lecture-based teaching models (more theoretical or demonstrative) that merely tell students about science (4). The participatory nature of the work plan was expected to engage students in the learning process. The program was designed to work with the basic contents of high school chemistry, physics, math, computing, and environmental science courses. Crucial problems that threatened the viability of the project were the difficulty of carrying it out within a rigid time schedule and the poor resources, common to most high schools. The solutions to the challenges posed by the limited time and the lack of resources are summarized below.

Table 1. Examples of Multidisciplinary Problems Posed to the Students

• Calculate the total solar energy over a given surface (their town) during one day and the cost of that energy if it could be transformed into electricity with a 100% yield.

• Calculate the rainfall in different units and the total volume of water in the town during a given time period.

• Record wind conditions in accordance with the Beaufort scale. • Obtain the town's wind rose from the distribution of wind speed and direction.

• Estimate the profitability of a wind farm in the town, taking into account the local wind speed and energy distributions. Note that wind is useful to generate energy only with speeds within the range 12-65 km/h

Consortium Schools A research consortium was established among scientists and university lecturers from the universities of Castilla-La Mancha and Huelva and high school teachers. The study was carried out in two towns in the continental area in the center of Spain where no pollution measurements had been previously made. The experiments were first carried out in the high school Alonso Quijano, located in Argamasilla de Calatrava, a small town with 6,000 inhabitants located approximately 5 km northwest of Puertollano, an industrial city with a refinery, petrochemical industries, and two power plants. Then, the experimental measurements were obtained in the high school Ribera del Bullaque in Porzuna, a village with 4,000 inhabitants located in a rural area whose main activity is agriculture. Both cities have dry, hot summers and dry, cold winters with frequent thermal inversions. During the thermal inversions, the dispersion of pollutants may be significantly reduced, leading to their accumulation. Wind, temperature, humidity, and solar radiation are important factors affecting the levels of pollutants that must be considered together with the emission sources. Previous studies measuring pollution levels have been carried out in the region (Ciudad Real and Puertollano) by differential optical absorption spectroscopy (DOAS) (5, 6). Furthermore, the Junta de Comunidades de Castilla-La Mancha (JCCM) has permanent air pollution monitoring stations in Puertollano as a part of the regional pollution surveillance network, and the data are accessible on its Web site (7). It was expected that ozone concentration levels in Argamasilla de Calatrava would be high owing to photochemical generation in the presence of the pollutants emitted in Puertollano. On the other hand, ozone levels in Porzuna were expected to be low, similar to those of a remote natural area (8). Project Outline The project was executed in different steps: a presentation at the high school, installation of the equipment, activities carried out in the classroom, final presentation, and a visit to the university. Presentation The project began early in the school year, when a university researcher gave a presentation on air pollution and air monitoring to the high school students. The researcher described the main sources and sinks of air pollutants and the effects on the

r 2011 American Chemical Society and Division of Chemical Education, Inc.

_

• Evaluate the air quality in the town. Compare the nocturnal and diurnal ozone levels in the town to those of other remote-natural (8) and polluted (13) areas in the world. Search for data from other larger cities and compare them.

• Analyze a daily ozone profile. Comment about the possible influence of solar radiation, wind, road traffic, refinery emissions, and so forth.

• By studying the evolution of the weather data during the last few days, students were asked to elaborate a weather forecast for the following day.

• From the data obtained from the ozone analyzer, different averages were calculated (1 min, 10 min, 1 h), which showed that the higher the average, the smaller the noise. Students were asked to decide the suitable time average for wind speed and direction, which usually experience rapid changes.

global and local environments. Then, attention was focused on ozone: its role in the troposphere, dependency on weather conditions, the chemical formation mechanisms, and relationship to atmospheric pollution and health problems (9, 10). Information about the regulated pollutant threshold levels (peak and average) for alert conditions was also included. The presentation then focused on training teachers and students in ozone monitoring. The equipment to be used in the project, the meteorological station and the ozone analyzer, were described. The presentation highlighted aspects that could be stimulating for students, such as the participation of university researchers, the availability of measurement facilities, and the fact that such measurements had never been made in their towns with the possibility to inform local authorities about ozone episodes above the established threshold levels. Installation of the Equipment The meteorological stations and ozone analyzers were placed on the flat roof of the school following the established guidelines (11) and were interfaced with the computers in the classroom, where real-time continuous data were obtained and saved. The analytical methods for air quality monitoring networks are well established in the United States and Europe and are described by Finlayson-Pitts and Pitts (9). Briefly, ozone measurements were carried out using ultraviolet absorption at

pubs.acs.org/jchemeduc

_

Vol. 88 No. 4 April 2011

_


393

In the Classroom

Figure 1. Hourly averaged data for ozone concentration and solar radiation on February 6, 2008 in Argamasilla de Calatrava.

253.7 nm (where ozone shows a maximum absorption cross-section) and the concentration determined by the Beer-Lambert law (which relates the intensity of radiation transmitted by a sample to the concentration of the absorbing species). This procedure has been shown to be sensitive and selective and is currently used as the standard measuring method by environmental agencies (12). An ozone analyzer from Environment, model O342M, that provides real-time continuous measurements was used. The weather conditions, pressure, temperature, rainfall data, and wind intensity, and wind direction were obtained by an automatic weather station (RainWise, Inc., model MKIII RTI-LR).1 Classroom Activities After 2 weeks of saving data, the teachers discussed the “general” profiles observed for the measured magnitudes: ozone concentration, temperature, solar radiation, wind speed and direction, rainfall, and the potential factors affecting them. Excel files (available in the supporting information) were developed to obtain and plot the data from the ozone analyzer and the weather station. Acquisition of the raw data was fully automated and the students were given continuous access to the merging and saved data in the classroom computers. The students were given instructions to obtain single data, temporal profiles, different time averages, correlations between parameters, summary tables, statistical data treatments, and so forth. Working in pairs, the students were in charge of monitoring the ozone levels for a week. They were to immediately inform the teachers about any ozone peak above the alert levels. On Friday, the student pair informed the rest of the classroom about the levels observed during the previous days, the ozone, wind, rainfall data events, and they compared the data to those from previous weeks. During the week, the teachers could ask the student pair about the current levels at any time. A sense of responsibility was instilled to make them feel that they were rendering a service to the community that no one else was rendering at the time. The availability of a data source from the students' environment is highly stimulating, as compared to values obtained from standard handbooks. In many cases, the students were asked not only to solve the problem, but also to provide the data. This requirement reinforced additional scientific and operational skills because the students must select and discriminate data and be conscious of the scales of the measured magnitudes. A few examples of the multidisciplinary problems posed to the students are listed in Table 1. 394


_


_

Figure 2. Monthly averaged ozone concentration during 2008 in Argamasilla de Calatrava.

Final Presentation At the end of the year, the teachers made a presentation of the results obtained during the year and the correlations found between ozone levels and weather conditions. This presentation started a discussion open to students and led by a teacher. University Visits A group of 20 students visited the University of Castilla-La Mancha (School of Chemistry, Ciudad Real). They toured the facilities of the Atmospheric Chemistry and Pollution research group and spent a day in a teaching laboratory carrying out two experiments related to indoor and outdoor pollution: “Determination of NOx and Particles in a Smokey Atmosphere” and “Computer Simulation of Atmospheric Pollution”. This visit was specifically for students in the last year of high school in the sciences or technology tracks. Results and Discussion We attempted to achieve educational objectives through the participation of students in a research study. Within this context, the experimental results were considered to be a tool more than the objective. Thus, the experimental results are only briefly discussed. As an example, typical diurnal ozone and radiation profiles are shown in Figure 1. As mentioned in the introduction, ozone is photochemically generated from solar radiation. The ozone maximum is found to be shifted (delayed) with respect to the radiation maximum, which shows that the photochemical


_


In the Classroom

Figure 3. Argamasilla de Calatrava and Porzuna ozone profiles (hourly averages for January 2008, Argamasilla de Calatrava, and January 2009, Porzuna).

equilibrium owing to reactions 1-3 is not instantaneous. The monthly averaged ozone concentrations are shown in Figure 2. The ozone maxima are observed during the months with longer days and greater radiation intensity. The weather was very cloudy during the month of May, which may explain the ozone minimum observed. The average ozone results from the two high schools are shown in Figure 3. The maximum found for Argamasilla de Calatrava is greater than that of Porzuna, but the residual levels are greater for the rural area (Porzuna). In Argamasilla de Calatrava, NO from traffic and factories probably reduces the nocturnal background ozone levels, producing NO2 (reaction 1). The project was surprisingly productive in the sense that many activities, questions, ideas, problems, applications, and so forth that had not been planned or programmed, emerged spontaneously. Each new activity in a given subject was communicated to the rest of the group and included in a growing list. All the teaching-learning materials from the activities carried out in the different subjects were processed to create a new multidisciplinary lecture unit available for the following years. The lecture unit has been included in the project report and is available to the project-funding institution, JCCM (with jurisdiction over Education within the region) and may be used by other high schools in the future. Evaluation This project was carried out throughout the entire school year in different class subjects, partially changing traditional teaching procedures (through interaction with the research study) but trying not to change or increase the curriculum content. In this sense, we considered that an additional, specific evaluation of the project by students was not necessary. Furthermore, students might have conceived the project as an additional burden during the year. During the year, we observed that the students were really interested in participating in the study. They usually watched the daily data even when they did not belong to the group in charge and asked questions about the results. Therefore, this work has proven to be an efficient mechanism to enhance the students' inquisitive nature. The coordination between the teachers of the different class subjects was good. A good coordination between several subjects has been found to be the only way to carry out such an experiment without dedicating too much time (from the point of view of


_

students). For teachers, the development of the project required additional effort during the first year. The opportunity to participate in a research study and the students' positive response to the experience was gratifying to them and compensated for the effort. This work has already resulted in participation in the Spanish Bi-Annual Physics Meeting (14) and a presentation in an international conference on education and new learning technologies (15). The results obtained may also be of interest to the towns of Argamasilla de Calatrava and Porzuna, primarily if unusually high levels of ozone are ever detected. As has been reported (2), ozone maximum peaks are often found a few kilometers from the emission sources of pollutants. In this regard, it is worth remembering that there are monitoring stations in the industrial city (Puertollano) but not in the surrounding areas (Argamasilla de Calatrava). During the reporting period, we observed only one ozone peak above the alert threshold limit (240 μg/m3) with a mixing ratio of 257.8 μg/m3, on June 27, 2008. On that date, the official monitoring station in Puertollano measured ozone peak values below 240 μg/m3. Summary We found that involving students in experimental research studies of topics related to their experience is an efficient method to stimulate their interest in science and their active participation in the learning process. Thus, this work corroborates much existing evidence on the educational advantages of collaboration among research scientists, high school teachers, and students in a project.2 Acknowledgment We wish to thank the Junta de Comunidades de Castilla-La Mancha for the financial support to conduct this work. Notes


1. The data were obtained during the periods JanuaryNovember, 2008 and January-November 2009 in Argamasilla de Calatrava and Porzuna, respectively. 2. The JCCM has just renewed its financial support for a new two-year project (2009-2011). An NOx analyzer is being incorporated into the monitoring station to better understand the behavior of tropospheric ozone.

_


_


395

In the Classroom

Literature Cited 1. Official Gazette of Castilla-La Mancha, March 17, 2009, 1178211799. Order of 09/03/2009, Regional Ministry of Education and Science. http://www.jccm.es/. http://docm.jccm.es/portaldocm/ descargarArchivo.do?ruta=2009/03/17/pdf/2009_3836.pdf&tipo=rutaDocm. 2. Klemm, O. J. Chem. Educ. 2001, 78 (12), 1641–1646. 3. Adams, E.; Smith, G.; Ward, T.; Vanek, D.; Marra, N.; Jones, D.; Henthorn, M.; Striebel, J. J. Chem. Educ. 2008, 85 (2), 221– 224. 4. Moore, J. W. J. Chem. Educ. 2009, 86 (4), 411. 5. Saiz-Lopez, A.; Notario, A.; Martínez, E.; Albaladejo, J. Water Air Soil Poll. 2006, 171, 153–167. 6. Saiz-Lopez, A.; Adame, J. A.; Notario, A.; Poblete, J.; Bolívar, J. P.; Albaladejo, J. Water, Air, Soil Pollut. 2009, 200, 277–288. 7. The Regional Air Quality Network. http://pagina.jccm.es/medioambiente/rvca/ultimosdatos2.htm. 8. Background pollutant levels. http://www.aemet.es/es/eltiempo/ observacion/contaminacionfondo. 9. Finlayson-Pitts, B. J.; Pitts, J. N., Jr. Chemistry of the Upper and Lower Atmosphere: Theory, Experiments, and Applications; Academic Press: San Diego, CA, 2000.

396


_


_

10. Seinfeld, J. H.; Pandis, S. N. Atmospheric Chemistry and Physics: From Air Pollution to Climate Change; John Wiley & Son: New York, 1997. 11. EPA. Ozone monitoring, mapping and public outreach. http://www. epa.gov/nrmrl/pubs/625r99007/625r99007.pdf (accessed Jan 2011). 12. European directive (2008/50/CE), BS EN 14625, 2005. Ambient air quality. Standard method for the measurement of the concentration of ozone by ultraviolet photometry. 13. The London Air Quality Network. http://www.londonair.org.uk. 14. Parra, J.; Mu~ noz, F.; Romero, E.; Parra, A.; Adame, J. A.; Díazde-Mera, Y.; Notario, A.; Aranda, A. “Física de la Atmosfera y Oceanografía”. XXXII Reunion Bienal de la RSEQ, Ciudad Real, Sept 7-11, 2009. http://bienalfisica09.uclm.es 15. Parra, A.; Romero, E.; Parra, J.; Mu~ noz, F.; Adame, J. A.; Díazde-Mera, Y.; Aranda, A.; Notario, A. International Association of Technology, Education and Development (IATED): EDULEARN, Barcelona, Jul 6-8, 2009. ISBN: 978-84-612-9802-0.

Supporting Information Available An Excel file containing experimental data for January 2008, for ozone, wind, radiation, temperature, humidity, and pressure; plots of the experimental measurements in hourly and daily scales; data used to plot Figures 1-3. This material is available via the Internet at http://pubs.acs.org.


_


A Research Study of Tropospheric Ozone and ... - ACS Publications

Recommend Documents