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Vol. 9 No. 1 - January 2003

Declining Global Air Quality:

Views From Student Interactions

By: Sagar V. Krupa

"Ignorance is a steep hill that perils rock at the bottom" -Anonymous

Recently one of my colleague and I taught an introductory undergraduate course "Air Pollution, People and Plants: The Science and the Ethics" for nonspecialists. Students in the class had diverse backgrounds ranging from Art - Biology - Chemistry - Engineering to preparatory education for entrance into the Medical School. Throughout the course, we strongly encouraged the students in the class to discuss various aspects of air quality concerns. We found that the students perceived those issues by reasons that were cognitive, emotional or ethical by nature. Independent of the underlying viewpoints, there was a consensus for preserving the environment through mitigation, societal adaptation or changing life styles and pollution prevention at the outset. There was a clear appreciation of the differences between being literate and being environmentally literate. Lack of self understanding of such a distinction can lead to intellectual positions that represent one extreme to the other. What is described in the following narrative represents student views of the global air quality issues from one classroom.

Clearly the chemical climate of the atmosphere has changed significantly during the last millennium. Plant biologists have come to realize the importance of the fundamental, integrative relationships between the chemical and physical climates of the earth. For example, changes in the chemistry or increases in the tropospheric concentrations of radiative trace gases such as carbon dioxide (C02) and ozone (03) and the consequent changes in the physics, the air temperature or precipitation patterns. Yet plant scientists in general, continue-to conduct uni-variate studies, although there are some exceptions. One can appreciate the underlying reasons - technical complexity of performing muti-variate studies, the need for mufti-disciplinary scientific

collaboration and the major limitations in securing the needed funding to conduct such studies. Stochastic or random variability in multiple plant growth regulating factors (e.g., air temperature, rainfall) forms the fundamental basis for the spatial and temporal variability in plant response to stress. Nevertheless, because of the dearth of knowledge as to how multi-variate systems work, to a large extent uni-variate studies have formed the basis for deriving air quality regulatory policies. Furthermore, such approaches as opposed to a multi-media viewpoint are easier to understand and to formulate policies. Overall, neither the scientists nor the policy makers have done a truly credible and defensible job in protecting the environment. While many scientists continue to state that more research is required, policy makers continue to argue that there is not enough information to assess costs for action and consequent benefits to be derived from such action. Here, frequently societal and political perceptions differ, as well as the mechanism of governance or implementation of a policy derived through a democracy (majority rule of the people) or through a republic (representation of the people by the elected).

With the exception of air pollutants such as the chloro-fluoro carbons (CFCs) that are purely anthropogenic in their origin, many others such as ground level ozone (03) or sulfur dioxide (SO2) are produced by both natural and anthropogenic processes. While SO2 is more of a local scale problem, 03 is the most important phytotoxic air pollutant worldwide. 03-induced plant injury has been reported from some 38 countries spanning N. America, Europe and AustralAsia (including India). Current evidence suggests that the so-called background levels of 03 at the surface have increased in all four continents. There are studies that show that a perennial, vegetatively propagated plant species originating from a geographic area with relatively high levels of 03 is more tolerant to elevated experimental 03 exposures compared to the same species originating from areas with relatively low levels of 03. That is to be expected, as part of the plant's adaptive strategy. In contrast, most interestingly, two recent, but unrelated studies have shown that a crop cultivar tolerant to 03 may perform poorly compared to an 03 sensitive cultivar when grown in clean or charcoal filtered air. The implications of such a finding in a future, hopefully cleanlier world are hard to assess at the moment. Clearly crop breeders have an interesting dilemma.

The famous 14th century English philosopher William of Ockham or simply Ockham wrote, "Entities should not be multiplied unnecessarily". Many scientists have followed Ockham's principle, creating the concept of "Ockham's Razor" which forces them to look for the simplest explanation. However, it does not mean that nature necessarily must oblige. There has been a rapid increase in the research on the effects of elevated CO2 on plants. At least in the agricultural context, many believe that elevated CO2 will benefit crop production, particularly since in many developed countries crops are managed under fertilization regimes and nonmoisture limiting conditions. Yet, a number of studies have shown that the positive effects of CO2 may be lost because of the negative effects of 03. Similarly, one study has shown that a SO2 sensitive bioindicator plant Ametanchier alnifolia can exhibit S02-induced foliar injury at concentrations well below the common ambient air quality standards, in the presence of moderates levels of 03. Although for decades plant scientists in general have recognized the major importance of the joint effects of multiple growth regulating factors, in their recent efforts, scientists within the United Nations-European Community are emphasizing the importance of factors that modify plant response to 03 in formulating a critical level(s) to protect vegetation against the risk of 03 damage. That is highly commendable. In contrast, it appears that policy makers in the US and Canada will not readily accept such an approach, because of differences in the administrative processes leading to setting air quality regulations (particularly because of the uncertainties associated with the risk analysis and the associated cost and benefit).

The so-called global warming is generally discussed in a deterministic fashion in the context of the global mean temperature. In contrast, at the local scale, in Minnesota for example, while the trend in average daily temperatures has remained steady during the past several decades, the trend in the night time mean temperatures is positive (increase). Such a phenomenon is paralleled by an increase in the frequency of occurrences of extreme precipitation events and in the total precipitation depth, coupled with the occurrence of spring floods. There is evidence to suggest that increases in night-time temperatures can adversely affect seed filling in grain crops. Coupled with changes in precipitation, there are other considerations such as changes in soil moisture, nutrient cycling and in the incidence of pathogens and pests.

The traditional view of most biologists has been, when conducting an experiment on the effects of one variable, all other variables must be held constant. Air pollution effects scientists have carried that philosophy to field experiments through the use of artificial exposure chambers. However, in the real world, application of that principle (constancy) is unreal. Many growth regulating factors including air pollutants vary simultaneously, sequentially, in the same or opposite directions and/or at random. Analysis of the effects of those patterns of exposures poses a daunting task to the effects scientists. In reality the question can be addressed if plant scientists accept - (a) the use of response surface methodology that emphasizes treatments over replicates, (b) the need to measure all the required growth regulating variables, (c) the need to define the dynamics of plant growth until harvest to account for feedback mechanisms and (d) the benefit of taking advantage of spatial variability in air quality-climate-plant interactions under real world conditions. The necessary mathematical tools for data analyses are available. It is the reluctance to venture into a challenging area of science and the need to develop very close and true collaboration on a mufti-disciplinary basis that are the stumbling blocks.

Most air pollution-vegetation effects scientists have emphasized research on air pollutant-induced visible foliar injury, on growth and yield responses and on the characterization of the behavior of biological indicator plants. More recently changes in biological diversity has become an issue of concern, particularly in the context of excess nitrogen loading as in The Netherlands. There is evidence to show that exposure to 03 can result in changes in species fitness (reproduction) without visible foliar injury or symptoms. It has been suggested that communities in productive habitats or those with a large legume fraction may be most 03 sensitive and communities at a late successional stage may be more resilient than those at an early state. Nevertheless, our current knowledge of that subject matter is very limited. While those issues are very important and critical, there are other needs that should also be addressed. Of concern is the accumulation of trace metals and persistent organic pollutants in edible plant parts consumed by animals and people (food chain). Of additional concern is the effect of air pollutants such as 03 on food quality (e.g., forage nutrient quality).

A very worrisome situation at least in the US is the virtually complete decline of funding during the last decade for research on the effects of air pollutants on plants. In the 1970s and the early 80s emphasis was on the effects of 03 on plants. As the public, fueled by the media identified acidic precipitation as the major environmental issue, research funding was shifted to address that question. Most recently funding for acidic rain research has completely disappeared at the expense of climate change. However, as noted previously in each case our efforts continue to be governed by uni-variate studies. One wonders whether such studies will provide defensible answers to a complex real world problem represented by a system of atmospheric processes and their products. Only time will tell.

At the end of our course, we were delighted to note that students one and all identified the need for holistic environmental effects studies, need for inter-disciplinary collaboration and science of better quality that is defensible among peers and the user community. What the students were unable to effectively define was how to implement such an approach in our country and at the global scale. They most certainly recognized the need for international cooperation, education and technology transfer. However, it was perceived from what has been published in the media that some developing countries needing such efforts associated themselves purely with their goal to achieve financial equity. Almost all of our students that go to college either with the help of student loans from the government or by working part-time after class hours did not concur with that argument of financial equity as a prerequisite for protecting the environment. It is important to note that undergraduate education at our universities is not free. On the other hand, our students were very willing to help preserve the environment as their personal resources permitted. It appears that some had volunteered through our global education programs, to work with people -in developing countries, using their own finances. Others had apparently traveled to countries to study local history, culture and just try to understand people. Clearly there is a need to further improve such activities.

Prof. S.V. Krupa is the Professor of Plant Pathology at the University of Minnesota, Twin City Campus, St. Paul, Minnesota, U.S.A. He is Life Member and an Advisor of International Society of Environmental Botanists, Lucknow.


This article has been reproduced from the archives of EnviroNews - Newsletter of ISEB India.


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