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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. |
