Progress 10/01/07 to 09/30/12
Outputs
OUTPUTS: One major objective of the project was to characterize the long-range transport of air pollutants and their impacts (changes in growth and/or yield) on crop and forest receptors downwind or farther away from source areas. A critical and a basic scientific issue is the need to understand the dispersion of pollutants over regional scales, including complex terrains (e.g. near large water bodies such as lakes, mountains and valleys). As a model system, the transport characteristics of sulfur dioxide emissions from a large coal-fired power plant and the path of its plume transport through a highly complex terrain of mountains and valleys was documented, separately during 1995-1999 and 1999-2003 (respectively before and after the implementation of a sulfur dioxide emission control system). The consequent results were presented at an International Symposium during the Annual North American Air Pollution Workshop in Banff (Canada) and as an invited chapter in a book from a leading international publisher in environmental sciences. Another objective of the project was to use the atmospheric movement of biological aerosols (fungal spores) as tracers to document long-range atmospheric transport of abiotic and biotic agents in particular, into Minnesota. The introduction of soybean rust spores through analysis of the preceding meteorological history of local temporal and spatial scale precipitation events was used as a tool and consequently a potential disease management scheme for the growers was developed. The results have been presented at Minnesota Soybean Grower Meetings, at national conferences on the Soybean Rust organized by the American Phytopathological Society and the results have also been published in peer reviewed international journals. It is hoped that a daily soybean rust disease forecasting system will be available through the University of Minnesota Extension Service for public use starting during the crop-growing season of 2010. PARTICIPANTS: M. Millan, (CEAM, Valencia, Spain) - Collaborative Research, Book Publication A.H. Bravo, (UNAM, Mexico City, Mexico) - Collaborative Research, Publication D. Gay, and V. Bowersox (Illinois State Water Survey, Champaign, IL) - Collaborative Research, Publication M.L. de Bauer (CP, Montecillo, Mexico) - Teaching M. Vazquez and S. Sanchez (University of Guadalajara, Guadalajara, Mexico) - Teaching D. K. Malvick and J. E. Kurle (University of Minnesota) - Collaborative Research G. Spoden (State of Minnesota DNR - Climatology Office) - Collaborative Research TARGET AUDIENCES: The complex terrain plume dispersion work is targeted to the fossil fuel combustion (energy) industry, air quality regulators, research community composed of meteorologists and environmental impact scientists. The soybean rust risk analysis work is targeted to Minnesota Soybean Growers and plant disease modelers at large. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Regarding the point source (power plant) plume monitoring, we used a mobile unit equipped with a Correlation Spectrometer (COSPEC, to measure the sulfur dioxide levels in the plume aloft) and a rapid response pulse fluorescence detector (for the simultaneous measurements of sulfur dioxide concentrations at the ground level). In 2003, 13 ecological monitoring plots consisting of Austrian pine (Pinus nigra) were established for long-term biological effect studies. Those plots were located using a Eularian Grid of 10 km squares using empirical wind direction from the source. To separate the contributions of the atmosphere from those of the soil to P. nigra foliar concentrations of total sulfur and other elements, an Elemental Enrichment Analysis (EEA) method was used. Based on the least amount of variance between several elemental concentrations in P. nigra needles and the corresponding soils in the plots, aluminum was chosen as the normalization element for computing elemental enrichment factors. Those results identifying sites with various levels of impacts were in close agreement with the results of measured plume transport and deposition in the complex terrain, before and after the installation of a sulfur dioxide emission control system. This represents the first of a kind study where complex terrain meteorology and terrestrial impact assessment have been linked. Equally importantly, the contributions of elemental pollution from the atmosphere could be separated from the background role of the soil. This is a major step in air quality-vegetation impacts assessment. The project was funded by CEAM (Centro de Estudios Ambientales del Mediterraneo, Valencia, Spain). Secondly, in a separate effort, dispersion of biological aerosols was used for studying long-range atmospheric transport of air pollutants (particulate matter) into Minnesota. A combination of HYSPLIT (Hybrid Single Particle Lagrangian Integrated Transport) model (developed by the National Oceanic and Atmospheric Administration, NOAA) and molecular techniques (Polymerase Chain Reaction, PCR) and DNA sequencing were used to show the transport of soybean rust spores from the Yucatan Peninsula (Mexico) to Minnesota and their deposition locally by precipitation. Consequently an integrated atmospheric model was developed for the risk prediction of the occurrence of soybean rust disease in Minnesota. The sub-modules of the model have been validated by real data used for daily forecasting and can be used by Minnesota soybean growers to apply fungicides for disease control (the only method known at this time) at the proper time to reduce their excess use and environmental contamination or increase conservation. Application of the risk-forecasting model can also save cost to the grower in disease control or management. The Minnesota Soybean Growers Association funded the project.
Publications
- Palau, J.L., Krupa, S., Calatayud, V., Sanz, M. and Millan, M. 2009. Relating source specific atmospheric sulphur dioxide inputs to ecological effects assessment in a complex terrain. In: Air Quality and Ecological Impacts: Relating Sources to Effects (Ed. A.H. Legge). Elsevier Science, Amsterdam, Netherlands, pp 99-120.
- Sosa, R.E., Bravo, A.H., Mugica, A.V., Sanchez, A.P., Bueno, L.E. and Krupa, S. 2009. Levels and source apportionment of volatile organic compounds in southwestern area of Mexico City. Environ. Pollut. 157: 1038-1044.
- Tao, Z., Malvick, D., Claybrooke, R., Floyd, C., Bernacchi, C., Spoden, G., Kurle, J., Gay, D., Bowersox, V. and Krupa, S. 2009. Predicting the risk of soybean rust in Minnesota based on an integrated atmospheric model. Int. J. Bio-Met. DOI 10.1007/s00484-009-0239-y.
- Yanez Morales, M.J., and Alanis Martinez, I., Soto Rocha, J.M., Malvick, D.K., Kurle, J.E., Floyd, C.M. and Krupa, S.V. 2009. Soybean Rust (Phakopsora pachyrhizi) Detected in the State of Campeche on the Yucatan Peninsula, Mexico. Plant Dis. DOI 10.1094/PDIS-93-0-00000.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: The work represents the first step in addressing objective 1: Develop numerical methods for relating integrated elemental accumulation in plant receptors to the contributions of air emissions from local and regional scale sources. The initial results have been presented during a Symposium at the 37th North American Air Pollution Workshop held in Banff, Alberta. A manuscript has been submitted for publication.
PARTICIPANTS: Fundacion CEAM (Fundacion Centro de Estudios Ambientales del Mediterraneo), Paterna (Valencia), Spain. Palau, J.L., Calatayud, V.,Sanz, M. and Millan, M.
TARGET AUDIENCES: Ecologists, Foresters, Energy industry and Government regulators. The work is still in its initial stages for transfer to the target audience.
Impacts
The Andorra Power Plant (APP) at Teruel, Aragon, Spain (40 degrees 54 minutes N, 1 degree 8 minutes W, 605 m asl), with a stack height of 343 m has three units, each with a 350 MW power-generating capacity. It uses 12,000 to 15,000 tons per day of low-grade lignite, with high sulphur content (5-6% and estimated SO2 emissions of 11.2 g/m3-S). A sulphur dioxide control (scrubber) system was installed in 1999. In an effort to understand the ecological impacts of APP SO2 emissions, separately during 1995-1999 and 1999-2003, the path of plume transport through a highly complex terrain of mountains and valleys was documented by the use of a mobile unit equipped with a Correlation Spectrometer (COSPEC, for the SO2 levels in the plume aloft) and a rapid response pulse fluorescence detector (for the simultaneous measurements of SO2 concentrations at the ground level). In 2003 thirteen ecological monitoring plots consisting of Austrian pine (Pinus nigra) were established for
long-term effects studies. These plots were located within the most frequent direction of plume transport. To separate the contributions of the atmosphere from the soil to the P. nigra foliar concentrations of total S and other elements, an Elemental Enrichment Analysis (EEA) method was used. Based on the least amount of variance between several elemental concentrations in P.nigra needles and the corresponding soils in the plots, Al was chosen as the normalization element in computing elemental enrichment factors. Those results identifying sites with various levels of impacts were in close agreement with the results of measured plume transport and deposition in the complex terrain, before and after the installation of the SO2 control system. Consequently additional studies are in progress to determine the long-term impacts of SO2 exposures on the growth and productivity of P. nigra.
Publications
- No publications reported this period
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Progress 01/01/06 to 12/31/06
Outputs
In lieu of using source-receptor analytical methods for chemical characterization, species specific biological aerosols (fungal spores) were used as a surrogate to study the atmospheric long-range transport (LRT) and introduction of polluted particulate matter (e.g., sulfate) into Minnesota. In 2005, weekly rain samples collected at 124 National Atmospheric Deposition Program/National Trends Network (NADP/NTN) sites in the eastern and central USA were screened for the exotic Asian Soybean Rust (ASR, Phakopsora pachyrhizi) spores (used as the tracer). Application of a quantitative Polymerase Chain Reaction (qPCR) method detected P. pachyrhizi DNA in the filter residue of rain samples collected during the week of 19-26 July 2005 in Minnesota, Missouri, and South Dakota. To determine the geographic origin of ASR spores in those weekly composite samples, back air trajectories of the lifted condensation and mixed boundary layers were calculated for each rain event within
the week, by sampling site. The calculations, based on the HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, pointed to source areas in eastern and southern Texas (TX). In a separate case, DNA of P. pachyrhizi was detected in a 28 June - 5 July 2005 rain sample from an eastern TX site. Back trajectories pointed to southern TX and the Yucatan Peninsula in Mexico as potential source areas of ASR spores. Vertical motions of those back trajectories indicated a ventilation of the boundary layer in the upwind areas, suggesting the possible injection of urediniospores into the free troposphere where they can be transported for long distances before wet deposition.
Impacts
Determining the frequency and magnitude of the occurrence of LRT (Long-Range Transport) of air pollutants into Minnesota can assist air quality regulators in assessing the efficacy of the State Implementation Plan (SIP) in upwind regions regarding pollutant emission management.
Publications
- Krupa, S., Bowersox, V., Claybrooke, R., Barnes, C.W., Szabo, L., Harlin, K. and Kurle, J. 2006. Introduction of soybean rust spores into the Midwestern United States. A Case Study. Plant Dis. 90, 1254-1259.
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Progress 01/01/05 to 12/31/05
Outputs
41.Phytotoxic effects of individual air pollutants on forage yield are well documented; however, little is known about their combined effects on yield, and even less is known about air pollution effects on forage quality. Alfalfa (Medicago sativa cv. Beaver) yield and nutritive quality responses to ambient concentrations of atmospheric ozone (O3), sulfur dioxide (SO2) and oxides of nitrogen (NOx) were assessed at three sites in west-central Alberta, Canada over five growing seasons (1998 to 2002). At each site, primary growth and re-growth harvests were taken from replicated plots, and air quality and meteorological parameters were monitored at appropriate time scales. Using median values across all study sites and years, yield data were separated into two different (p < 0.05) classes (low and high) and utilized in multiple regression analysis of alfalfa yield and nutritive quality responses. Across all harvests, air quality and meteorological factors accounted for
two-thirds (adj. R2 = 0.67, p < 0.001) of the variability in alfalfa yield; air quality influenced half of the accounted variation, with O3 alone accounting for 25%. Ozone and precipitation contributed 69 and 17%, respectively; to the variability in percentage CP (Crude Protein) of low-yielding alfalfa that was attributable (adj. R2 = 0.52, p = 0.003) to air quality and meteorological parameters, and temperature and humidity collectively influenced 98% of the accounted variation (adj. R2 = 0.52, p = 0.003) in percentage CP of high-yielding alfalfa. Three-fourths of the accounted variation (adj. R2 = 0.58, p< 0.001) in relative feed value (RFV, calculated from forage concentrations of ADF, Acid Digestible Fiber and NDF, Non-Digestible Fiber) of low-yielding alfalfa was attributable to meteorological parameters, whereas air quality contributed 25%. In contrast, air quality (primarily O3) influenced 86% of the accounted variation (adj. R2 = 0.47, p = 0.199) in RFV of high-yielding
alfalfa, and temperature and precipitation collectively contributed 14%. Elucidation of causal relationships between air quality, crop yield and nutritive quality represents a novel and potentially useful application of air pollution research to forage-based animal production systems.
Impacts
Ambient air quality (ozone, sulfur dioxide and the oxides of nitrogen) or air pollutant mixtures can modify forage nutritive quality for ruminant animals. The research is based on real world conditions (open atmosphere and crop management by the farmer) and represents a novel and potentially useful application of air pollution research to forage-based animal production systems, particularly in rapidly developing countries such as China and India.
Publications
- Lin, J., Nosal, M., Muntifering, R. and Krupa, S. 2005. Alfalfa yield and nutritive quality as influenced by air quality in west-central Alberta. J. Ani. Sci. 83 (Suppl.1). 149.
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Progress 01/01/04 to 12/31/04
Outputs
Ozone (03) at the Earth's surface is present everywhere and is produced predominantly by human activity. By 2030 03 levels are expected to increase by some 22 percent (Asia and other developing nations) and about 16 percent elsewhere (N. America and Europe). Numerous studies have shown ambient 03-induced injury to plant foliage (from about 40 countries) and crop growth and yield losses. Only recently has evidence begun to emerge that 03-induced alterations in nutritive quality for ruminant animals, combined with yield reductions may be much more important than forage yield losses alone. Published literature on the effects of ambient 03 on plant nutritive quality for humans and animals is very sparse. Nevertheless, evidence strongly supports the fact that ambient 03 can alter the plant food quality for ruminant animals. In addition to indirect effects through changes in carbon and nitrogen allocation between various plant organs (shoots versus roots), 03 can alter the
characteristics of forage ingestion and digestion by animals. In that context, Consumable Food Value (CFV), can be defined as: on a scale of 0.0 to 1.0 = [Fractional reduction in dry matter yield] x [Fractional reduction in nutritive quality]. In a mixture of rye grass and white clover, dry matter production of the mixture was reduced by only 5 percent (0.95 of control, exposure to charcoal filtered air). In contrast the nutritive quality was reduced by 10.5 percent (0.895 of control). Thus, the CFV or the Consumable Food Value was (0.95 x 0.895) 0.85 or a 15 percent reduction. This is an extremely important finding, because CFV can be much more significant than yield reductions alone in the assessments of true economic impacts of 03 on forage. In the present work, for comparative purposes, other similar experimental databases were analyzed through meta-analyses to derive additional validation of the conclusion regarding the impacts of tropospheric 03 on ruminant animal nutrition.
Impacts
The present work emphasizes the importance of ozone and other air pollutants (factors involved in global climate change) in not only causing adverse effects on crop yields, but also on their nutritive quality. This is a very important consideration in sustaining future animal husbandry.
Publications
- Krupa, S.V., Muntifering, R. & Chappelka, A.H. (2004). Effects of ozone on plant nutritive quality characteristics for ruminant animals. The Botanica 54, 1-12.
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Progress 01/01/03 to 12/31/03
Outputs
At the global scale, among all nitrogen species in the atmosphere and their deposition on to terrestrial vegetation and other receptors, NH3(ammonia) is considered to be the foremost. The major sources for atmospheric NH3 are agricultural activities and animal feedlot operations, followed by biomass burning (including forest fires) and to a lesser extent fossil fuel combustion. Close to its sources, acute exposures to NH3 can result in visible foliar injury on vegetation. NH3 is deposited rapidly within the first 4-5 km from its source. However, NH3 is also converted in the atmosphere to fine particle NH4+ (ammonium) aerosols that are a regional scale problem. Adverse effects of NH3 on vegetation occur when the rate of foliar uptake of NH3 is greater than the rate and capacity for in vivo detoxification by the plants. Most to least sensitive plant species to NH3 are native vegetation > forests > agricultural crops. There are also a number of studies on N deposition
and lichens, mosses and green algae. Direct cause and effect relationships in most of those cases (exceptions being those locations very close to point sources) are confounded by other environmental factors, particularly changes in the ambient S02 (sulfur dioxide) concentrations. In addition to direct foliar injury, adverse effects of NH3 on higher plants include alterations in: growth and productivity, tissue content of nutrients and toxic elements, drought and frost tolerance, responses to insect pests and disease causing microorganisms (pathogens), development of beneficial root symbiotic or mycorrhizal associations and inter species competition or biodiversity. In all these cases, the joint effects of NH3 with other air pollutants such as all-pervasive O3 or increasing C02 concentrations are poorly understood. While NH3 uptake in higher plants occurs through the shoots, NH4+ uptake occurs through the shoots, roots and through both pathways. However, NH4+ is immobile in the soil
and is converted to N03- (nitrate). In agricultural systems, additions of N03- to the soil (initially as NH3 or NH4+) and the consequent increases in the emissions of N20 (nitrous oxide, a greenhouse gas) and leaching of N03- into the ground and surface waters are of major environmental concern. At the ecosystem level NH3 deposition cannot be viewed alone, but in the context of total N deposition. There are a number of forest ecosystems in North America that have been subjected to N saturation and the consequent negative effects. There are also heath lands and other plant communities in Europe that have been subjected to N-induced alterations. Regulatory mitigative approaches to these problems include the use of N saturation data or the concept of critical loads. Current information suggests that a critical load of 5-10 kg ha- yr-1 of total N deposition (both dry and wet deposition combined of all atmospheric N species) would protect the most vulnerable terrestrial ecosystems (heaths,
bogs, cryptogams) and values of 10-20 kg ha-1 yr-1 would protect forests, depending on soil conditions.
Impacts
At the global scale, among all nitrogen species in the atmosphere and their deposition on to terrestrial vegetation, ammonia is considered to be the foremost. In addition to direct foliar injury, adverse effects of ammonia on higher plants include alterations in: growth and productivity, drought and frost tolerance, responses to insect pests and pathogens.
Publications
- Krupa, S. V. (2003). Effects of atmospheric ammonia (NH3) on terrestrial vegetation: A review. Environ. Pollut. 124, 179-221.
- Krupa, S. V. (2003). Atmosphere and agriculture in the new millennium. Environ. Pollut. 126, 293-300.
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Progress 01/01/02 to 12/31/02
Outputs
Additions of anthropogenic nitrogen (N) compounds constitute one of the major classes of air pollutants of significance to human health and the environment. Reliance on wet deposition measurements alone can lead to considerable underestimates (by 40-60%) of the total (wet + dry) atmospheric N deposition. In addition, wet deposition of N is about 20% of the levels that are lost due to volatilization (primarily ammonia). Nevertheless, in the agricultural sectors of the Mississippi River basins, farm management practices, and recycling of N within cropping systems clearly outweigh the contributions of atmospheric deposition. As opposed to native vegetation and forests, there are no records of the negative effects of atmospheric N deposition on crop yield. Similarly field studies on the interactions of atmospheric N compounds with the incidence and spread of pathogens does not permit any generalizations. Nitrogen applied as fertilizer affects disease probably more by its
effect on the plant growth than by its effects on pathogens. In contrast atmospheric nitrogen dioxide appears to be a stimulant of aphid performance. Under conditions of heavy weed infestation, N fertilization stimulates weed growth and competitiveness, rather crop yield.
Impacts
Nitrogen saturation of ecosystems is a critical environmental issue. The described work is highly relevant to the assessment of the contributions of atmospheric nitrogen deposition to the US agriculture sector.
Publications
- Krupa, S. V. and Moncrief, J. F. 2002. An integrative analysis of the role of atmospheric deposition and land management practices on nitrogen in the U.S. agricultural sector. Environ. Pollut. 118: 273-283.
- Legge, A. H. and Krupa, S. V. 2002. Effects of sulphur dioxide. In Air Pollution and Plant Life, 2 ed., eds. J. N. B. Bell and M. Treshow. John Wiley & Sons Ltd., Chichester, United Kingdom. pp. 135-162.
- Krupa, S. V. 2002. Sampling and physico-chemical analysis of precipitation: A review. Environ. Pollut. 120: 565-594. Millan, M., Sanz, M.J. and Krupa, S. (eds.). 2002. Environment and Agriculture: the Nitrogen Compounds. Environ. Pollut. (Special Issue) 118(2): 165-283.
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Progress 01/01/01 to 12/31/01
Outputs
Field surveys for symptoms of foliar injury in a regional airshed that is influenced by a number of point sources of S0X (oxides of sulfur), N0X (oxides of nitrogen) and hydrocarbons, combined with foliar and soil sulfur (S) analyses, confirmed earlier observations that Saskatoon serviceberry (Amelanchier alnifolia Nutt.) cv. Smokey can be used as a biological indicator of chronic sulfur dioxide (S02) exposures, in the presence of other phytotoxic air pollutants such as ozone (03). During one year, interveinal chlorosis was observed in July - August, followed by mild necrosis in September. During the second year, symptoms were relatively mild (interveinal chlorosis) and appeared only in September, due to climatic conditions that slowed-down the rate of plant growth. Nevertheless, atmospheric S deposition was the cause of the observed foliar injury, as indicated by the foliar organic-S to inorganic or sulfate-S ratios. Their values were the lowest in the injured (9.5),
followed by the slightly injured (11.3) leaves suggesting higher levels of sulfite + sulfate accumulation, compared to uninjured leaves (21.2 - 27.7, higher accumulation of organic S) from several other study sites. These trends in foliar S status and occurrence of visible injury were consistent during the two successive years. However, during both years, maximum hourly sulfur dioxide (S02) concentrations were <50 ppb, while maximum hourly ozone concentrations were in the 60 -70 ppb range. For comparison, in the US the current secondary ambient air quality standards, respectively for S02 and 03 are: 3-hour average of 0.5 ppm and a running 8-hour average of 80 ppb. Both these standards are not to be exceeded more than once per year at a given location.
Impacts
The work is highly relevant to the use of higher plants, under the real world field conditions, as biological indicators of air quality.
Publications
- Krupa, S. V. 2001. Air pollution injury. In: Pea Compendium, Eds. Kraft, J.L. and Pfleger, F.L. APS Press, St. Paul. 53 pp.
- Krupa, S.V. and Legge, A.H. 2001. Saskatoon serviceberry and ambient sulfur dioxide exposures: study sites re-visited, 1999. Environ. Pollut. 111:363-365.
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Progress 01/01/00 to 12/31/00
Outputs
A previously developed multivariate, non-linear, time series model is being applied to evaluate the effects of multiple air pollutants (ozone, sulfur dioxide and the oxides on nitrogen) and environmental factors (air temperature, precipitation depth, relative humidity, photosynthetic radiation etc.) on the yield of alfalfa under ambient, open-field growing conditions at three locations. The time series (10-day intervals) for defining the independent variables in discrete periods of the plant biology or physiological phenology is based on the measured and modeled growth rates of the crop during each harvest. Each of the study sites consists of multiple years of alfalfa seedings in a five- year rotation. Discounting the effect of weeds, the concentrations of ozone, sulfur dioxide and the oxides of nitrogen proved to be three of the four important contributors to the alfalfa biomass at site #1 with 1996-98 seedings. In comparison, in addition to ozone, precipitation and
temperature were two of the four major factors (discounting the weeds) in influencing the alfalfa growth at site #2. The situation at site #3 (this site was started later than the other two, therefore 1998 seeding only) was somewhat similar to site #1. Again, these overall observations do not mean alfalfa yield reductions at this point. This question can only be determined by comparing yields between harvests and years at each study site and between sites. As the study continues and as information accumulates on sufficient number of harvests to define the response surface more fully, meaningful conclusions will be reached regarding the yield response issues.
Impacts
The work has very important consequences in examining the joint effects of multiple air pollutants and environmental factors on crop yield under the real world field conditions.
Publications
- Krupa, S.V. & Groth, J.V. (2000). Global climate change and crop responses: Uncertainties associated with the current methodologies. In: Environmental Pollution and Plant Responses, eds. S.B. Agrawal & M. Agrawal. CRC Press, Boca Raton, FL, pp 1-18.
- Krupa, S.V. (2000). Ultraviolet (UV)-B radiation, ozone and plant biology. Environmental Pollution 110:193-194.
- Krupa, S.V. (2000). Air Pollution. In: The Encyclopedia of Plant Pathology, eds. O.C. Maloy & T.D. Murray. John Wiley, New York, pp 26-29.
- Krupa, S.V. (2000). Air Pollutants. In: The Encyclopedia of Plant Pathology, eds. O.C. Maloy & T.D. Murray. John Wiley, New York, pp 24-26.
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Progress 01/01/99 to 12/31/99
Outputs
Saskatoon serviceberry or Saskatoon (Amelanchier alnifolia Nutt. cv. Smoky) seedlings were planted at five study sites within a 35,000 km2 airshed, that is influenced by a number of isolated stationary sources of sulfur dioxide (S02), oxides of nitrogen (N0x) and hydrocarbons (RHs), among others. The locations of the five sites were based on the results of a meteorological dry deposition model for the oxides of sulfur and nitrogen. Visible foliar injury responses of Saskatoon were used as a biological indicator of S02 exposures, through monthly field surveys. During late July 1998, unifacial, interveinal chlorosis was observed on some 12% of the 100 seedlings at one study site. By September, the chlorosis had become more severe (necrosis) on some 70% of the plants at that site. During the 1999 growth season, similar foliar injury was again observed, but it was slow in developing (September), was present only on about 34% of the plants at the affected site and was
restricted to mild, interveinal chlorosis. Most likely the occurrence of these mild symptoms late in the season was because of the delayed onset of spring growth, due to unusually cold and wet weather during the early part of the growth period. Site specific ambient S02 levels were relatively low (maximum 5-minute concentration of 52.8 ppb) during the two growing seasons combined. Similar data were unavailable for all, but one (1998) or two (1999) other sites. Therefore, foliar total S and S042--S concentrations were analyzed in 1998 and 1999 using samples collected during September of each year, at four of the five study sites. Soil S042-S levels at these sites were also analyzed. There were spatial variabilities among these parameters. However, there were also logically explicable patterns in the relationships between foliar, total; inorganic; and organic S fractions and soil S at the different study sites. Based on the overall examination of these data, it was concluded that the
observed visible injury symptoms were due to chronic S02 exposures, exacerbated by the presence of ozone (03). Independent of this literature-based hypothesis, visible foliar injury responses of Saskatoon can be used as a biological indicator for acute or chronic ambient S02 exposures, in the presence of other phytotoxic air pollutants.
Impacts
The work has important consequences in the use of sensitive plants as biological indicators of air quality, affecting environmental and quality of life values. The target audience is the energy sector and the outcome can lead to changes in pollutant emissions.
Publications
- Krupa, S. V. & Nosal, M. (1999). Rainfall composition in Minnesota: Integrating the chemistry, synoptic meteorology and numerical modeling. Environ. Pollut., 104, 477-483.
- Krupa, S. V. & Legge, A. H. (1999). Foliar injury symptoms of Saskatoon serviceberry (Amelanchier alnifolia Nutt.) as a biological indicator of ambient sulfur dioxide exposures. Environ. Pollut., 106, 449-454.
- Krupa, S.V. & Legge, A.H. (1999). Passive sampling of ambient gaseous air pollutants: an assessment from an ecological perspective. Environ. Pollut, 107, 31-45.
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Progress 01/01/98 to 12/31/98
Outputs
Clear quantitative differences were observed in the chemical composition of rain collected by an in situ, refrigerated event sampler versus using a non-refrigerated, composite, weekly sampling protocol, at a site in the upper Midwestern USA. There was a non-linear, parabolic relationship between pH and S042 or N03 concentrations. Such relationships could be stratified by the occurrences of three different classes of rainfall chemistry, governed by three different types of branching air trajectories preceding them. These overall processes were influenced by source-receptor issues. A Fourier modulated, three-way parabolic spline regression model was used to explain the non-linear relationships between H+ and S042- or N03-. This model performed much better (R2:0.48-0.61) than the linear (R20:008-0.31) and non-modulated three-way parabolic spline (R2:0.22-0.36) regression analyses. Overall, the study allowed an integration of rainfall chemistry with synoptic meteorology
and numerical modeling.
Impacts
(N/A)
Publications
- Krupa, S. V. & Legge, A. H. (1998). Sulphur dioxide, particulate sulphur and their impacts on a boreal forest ecosystem. In Modern Trends in Ecology and Environment, ed. R. S. Ambasht. Backhuys Publishers, Leiden, The Netherlands, pp. 285-306.
- Krupa, S. V. (1998). Passive sampling of ambient, gaseous air pollutants: A review. pp. 485-505. In Proc. Int. Spec. Conf., Emerging Air Issues for the 21st Century: The Need for Multidisciplinary Management, eds. A.H. Legge & L.L. Jones. Air & Waste Management Association, Pittsburgh, PA, 626 pp.
- Legge, A. H., Jager, H.-J. & Krupa, S. V. (1998). Sulfur dioxide. In Recognition of Air Pollution Injury to Vegetation: A Pictorial Atlas, ed. R. B. Flagler. Air & Waste Management Association, Pittsburgh, PA, pp. 3-1 - 3-42.
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Progress 01/01/97 to 12/31/97
Outputs
Statistical analysis was performed using select sets of combined data from the U.S. National Crop Loss Assessment Network (NCLAN) and the European Open-Top Chambers Programme (EOTCP) to examine the relationships between the occurrences of hourly ambient ozone (O3) concentrations and adverse crop yield responses. The results suggest that the frequency of occurrences of relatively low hourly O3 concentrations ( < 35 ppb) are not as important as moderate to higher concentrations in eliciting negative crop biomass responses. They also suggest that daily peak (highest) hourly O3 values ( > 90 ppb) may not be as critical, most likely because, they frequently do not occur during time periods when conditions that promote atmospheric conductivity (O3 deposition) and plant uptake (O3 absorption) are in coherence.
Impacts
(N/A)
Publications
- Krupa, S. V. 1997. Global climate change: Processes and products - An overview. Environ. Monitor. Assess., 46, 73-88.
- Rogers, H. H., Runion, G. B., Krupa, S. V. & Prior, S. A. 1997. Plant responses to atmospheric CO2 enrichment: Implications in root-soil-microbe interactions. In Advances in CO2 Research, eds. L. H. Allen Jr., M. B. Kirkham, D. M. Olszyk & C. E. Whitman. Agronomy Society of America, Spec. Publ. #61, Madison, WI, pp. 1-34.
- Krupa, S. V. 1997. Air Pollution, People and Plants. APS Press, Minneapolis, MN, 197 pp.
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Progress 01/01/96 to 12/30/96
Outputs
Exponential growth curve model was developed for Pinus contorta Loud x Pinus banksiana Lamb (lodgepole x jack pine) trees, from basal area increment data collected from 5 ecologically-analogous sampling locations (AI to AV) in the vicinity of a sulphur recovery sour gas processing plant emitting sulphur (S) gases in the West Whitecourt study area near Whitecourt in Alberta, Canada. The mean basal area increment growth declined by 1.2%, 1.4%, 0.8% & 0.6% between 1959 & 1981 at locations AI, AII, AIII and AIV. There's been an increase in wood production at impacted sites, AI to AIV. This was the result of reductions in total sulphur gas emissions from 1963 to 1981, of 58,403 t S/y to 6,782 t S/y. A Multivariate-nonlinear, Polynomial Fourier (MPF) regression model was applied to explain the relationships between the ambient S02 exposures at the 5 sampling locations & changes in pine tree basal area increment growth. The MPF regression model included the ambient S02
exposure parameters: 1) # of episodes; 2) cumulative integral of exposures; & 3) peak episodal concentrations. Model parameters were est. using the least squares approach. The MPF regression model captured the effects of the episodicity of S02 exposures on radial tree growth of pine species & provided a high degree of forecasting power due to the use of the integral of the S02 exposures. Peak episodal S02 concentrations or the # of episodes appeared not to play as important a role in the model as the integral.
Impacts
(N/A)
Publications
- Krupa, S.V. (1996). The role of atmospheric chemistry in the assessment of crop growth and productivity. In Plant Response to Air Pollution, eds. M. Yunus & M. Iqbal. John Wiley & Sons, Chichester, England, pp. 35-73.
- Legge, A.H., Nosal, M. & Krupa, S.V. (1996). Modeling the numerical relationships betwen chronic ambient sulphur dioxide exposures and tree growth. Can. J. Forest Res. 26:689-0695.
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Progress 01/01/95 to 12/30/95
Outputs
Federal regulations prohibit use of vehicles, electricity, etc. in Class I wilderness areas. Continuous (active) ozone (03) monitors that require electric power cannot be used at these locations. Therefore, to improve our understanding of the use of passive 03 monitors, ambient 03 was measured in two Class I areas within White Mountain National Forest, NH and at one Class I location within the Green Mountain National Forest, VT, for six weeks between July 5 and August 16, 1994, using passive nitrite-coated filter samplers and a one week exposure period each time. Results for 7-day mean ambient 03 concentrations from the passive samplers were compared to co-located continuous ultraviolet photometric 03 analyzers. With the exception of one value, percent differences of the concentrations obtained from the passive sampler compared to the continuous 03 monitor were within the range (20%) of the published values from other studies. Although the size of the data set was
small agreement through simple linear regression between mean 7-day 03 concentrations determined by the continuous monitors, and those obtained from the passive samplers was generally very good (adjusted R2=0.759; p=0.0003).
Impacts
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Publications
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Progress 01/01/94 to 12/30/94
Outputs
In an effort to develop a cohesive view of the dynamics of ambient O3 exposure and adverse crop response, results from two independent approaches (a: statistical and b: micrometeorological) were analyzed for understanding cause-effect relationships of the foliar injury responses of tobacco cv. Bel-W3 to the exposure dynamics of ambient O3 concentrations. Similarly, other results from two independent approaches were analyzed in: (1) establishing a micrometeorological relationship between hourly ambient O3 concentrations and their vertical flux from the air into a natural grassland canopy and (2) establishing a statistical relationship between hourly ambient O3 concentrations in long-term, chronic exposures and crop yield reductions. Independent of the approach used, atmospheric conditions appeared to be most conducive and the crop response appeared to be best explained statistically by the cumulative frequency of hourly ambient O3 concentrations between 50 ppb and 90
ppb. In general, this concentration range represents intermediate or moderately enhanced hourly O3 values in a polluted environment. Further, the diurnal occurrence of this concentration range (often approximately between 0900 and 1600 hours in a polluted, agricultural environment) coincided with the optimal CO2 flux from the atmosphere into the crop canopy, thus high uptake.
Impacts
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Publications
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Progress 01/01/93 to 12/30/93
Outputs
A retrospective mathematical analysis was performed on the U.S. NCLAN (National Crop Loss Assessment Network) open-top chamber O(subscript 3) exposure-crop response data. Some 77% of the 73 crop harvests examined, showed no statistically significant yield differences between NF (non-filtered open-top chamber) and AA (chamberless ambient air) treatments (no easily discernable chamber effects on yield). However, among these cases only 7 acceptable examples showed statistically significant yield reductions in NF compared to the CF (charcoal filtered open-top chamber) treatment. An examination of the combined or cumulative hourly ambient O(subscript 3) frequency distribution for cases with yield loss in NF compared to a similar match of cases without yield loss showed that the mean, median and the various percentiles were all higher (/>-/ 3, xx) in the former in contrast to the latter scenario. The combined frequency distribution of hourly O(subscript 3) concentrations for
the cases with yield loss in NF clearly separated from the corresponding distribution with no yield loss, at O(subscript 3) concentrations > 49 ppb. Univariate linear regressions between various O(subscript 3) exposure parameters and percent yield losses in NF showed that the cumulative frequency of occurrence of O(subscript 3) concentrations between 50 and 87 ppb was the best predictor (adjusted R(superscript 2) = 0.712 and p = 0.011).
Impacts
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Publications
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Progress 01/01/92 to 12/30/92
Outputs
Numerical analyses were performed with the results from an open-top chamber exposure study conducted at two locations in the northeast USA, utilizing tobacco (Nicotiana tabacum L.) cv. Bel-W3 (sensitive) and cv. Bel-B (tolerant) as differential indicators of ambient O(subscript 3) pollution. At both study sites Bel-W3 was significantly more sensitive than Bel-B. There were differences in the weekly O(subscript 3) exposure dynamics and the consequent foliar injury scores on Bel-W3 between the two study sites. During the individual weekly exposures, the bottommost fully expanded leaf (leaf #1) on Bel-W3 was more sensitive than the second fully expanded leaf (leaf #2). There were no statistically significant differences in the injury scores on Bel-W3 leaf #1, between the non-filtered air open-top chamber and the chamberless, ambient field plot treatments at both study sites. In Mallow's critical point best regression, among the many O(subscript 3) descriptors tested,
number of hours during each week with O(subscript 3) concentrations > 40 ppb (N40) and > 60 ppb (N60) or the corresponding sum of their concentrations (SUM40 and SUM60) proved to be the best predictors of foliar injury on Bel-W3, leaf #1. The regression used N40 and N60 or SUM40 and SUM60 together and did not identify each variable alone or by itself as being important.
Impacts
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Publications
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Progress 01/01/91 to 12/30/91
Outputs
The bulk modulus of elasticity (E) for Pinus contorta (lodgepole pine) x Pinus banksiana (jack pine) hybrids was compared between a site (A(i)) close to a sour gas processing plant and a control site (A(v)). The mean bulk modulus of elasticity for branches from A(i) ws 47.5 MPa vs. 18.5 MPa for the control site (A(v)). Site A(i) had been exposed to S-gas emissions and large amounts of elemental S deposition and had an acidic soil (pH 4.0 at 10 cm depth). During 1981 the needles at A(i) had more aluminum and iron compared to those at A(v) (900 ppm vs. 390 ppm Al in the 3-year old needles). Mean leader growth was measured over a 3 year period and was observed to be greater at A(i) than A(v) (46 +/- 7 cm vs. 29 +/- 9 cm for 1988). Histochemically, the needles at A(i) had higher phenol and lignin content than A(v). These results suggest that the S-gas fumigation, S-dust deposition, plus increased concentrations of soluble aluminum and iron had altered the cell wall
elastic properties resulting in altered water relations. This has implications in our understanding of stress induced changes in leaf diffusive resistance and photosynthesis.
Impacts
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Publications
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Progress 01/01/90 to 12/30/90
Outputs
Virtually all of our present knowledge on the effects of air pollutants on cropsand tree species is based on relating air concentrations of pollutants and measuredplant responses (exposure dose). However, it is well known that it is not the airconcentration, but the pollutant concentration absorbed by the plant that leads to an effect (effective dose). There are numerous methodological problems in measuring the actual pollutant uptake by plants under field conditions. In an effort to further our understanding of the effective dose, an experiment was conducted to study the effects of sulfur dioxide, oxides of nitrogen and ozone on an open grassland. Carbon dioxide and water vapor flux were used as indicators of plant response, coupled with biomass measurements at several time intervals during the growth season. It was observed that the pollutant flux was not always related to its air concentration. Thus, high pollutant concentrations do not necessarily mean high plant
uptake. Conversely low air concentrations could lead to high uptake. These results are contrary to the accepted theory that high episodic air concentrations always lead to more adverse effects in a chronic situation. In order to explain the observed results, an atmospheric pollutant exposure model, a pasture growth model and a soil hydrologic, erosion model are being coupled.
Impacts
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Publications
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Progress 01/01/89 to 12/30/89
Outputs
Over the past 20 years, numerous field experiments have been conducted to determine the adverse effects of atmospheric ozone (0(3)) on crop productivity. One of the key issues in all these studies is to identify what a control or reference point of ozone exposure should be in comparisons against present day ambient or above ambient 0(3) treatments. In an attempt to answer this question, ambient surface 0(3) exposure patterns were examined at 14 so-called "clean" geographic locations (from the South Pole to Barrow, Alaska). At these sites, warm season, average 7-h daily 0(3) concentrations ranged from 0.028 to 0.050 ppm. An appropriate reference point for N. America may be 0.030 - 0.45 ppm 0(3) concentration. Thus, the frequently used reference value of 0.025 ppm in crop response assessment, results in an over-estimation of 0(3) - induced crop loss. Decision markers must take this into account in developing future regulatory policies.
Impacts
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Publications
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Progress 01/01/88 to 12/30/88
Outputs
The relationship between ambient ozone exposure and crop response is inherently stochastic in nature. Ambient ozone exposure is a dynamic time series in space. The crop response is also dynamic, varying in sensitivity with the rate of change in growth. Final yield responses are the result of the interactions between these overall processes. Spectral coherence analysis was used in an attempt to understand the relationship between the time series of ozone exposure profiles and changes in alfalfa height growth. When variations between daily ozone exposure profiles were low, median hourly ozone concentration was in best coherence with the time series of alfalfa height growth. When variations between daily ozone exposure profiles were high, the cumulative integral of exposure was in best coherence with the time series of alfalfa height growth. These results suggest that the ozone exposure parameter that best describes the changes in crop growth may be highly time and
site specific. This may also explain why no single universal descriptor of ozone exposure has yet been found that may best describe crop response.
Impacts
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Publications
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Progress 01/01/87 to 12/30/87
Outputs
The occurrences of air pollutants are considered to be stochastic. Different phenological or growth stages of crops respond differently to air pollutant exposure (concentration and exposure duration). An exponential growth model was developed to describe the height growth of alfalfa: y = A(1-eambdat)k; where y = weekly height growth; t = date in Julian days (age); and A, lambda, and K = model coefficients, estimated by least squares. Subsequently, a pollutant exposure-biomass response model was developed: y = sigma/(i) sigma/(n) sigma/(t)an(t)x(i)n(t); where y = alfalfa leaf dry weight per 100 stems; i = 1, 2, 3,. . ., polluttant exposure parameter (concentration, frequency of exposure, cummative integral of exposure etc.); n = 1, 2, 3((n)). . ., power of the non-linear term; t = 1, 2, 3, . . ., time series of alfalfa height growth; a(i)(t) = regression coefficient; and x(i)n(t) = exposure quantification term. These models represent the first effort anywhere to
evaluate dynamic time series and relationships between air pollutant exposure and plant response. Ambient, chamberless fieldexperiments are in progress to validate the model at this time.
Impacts
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Publications
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Progress 01/01/86 to 12/30/86
Outputs
During the summers of 1982 through 1984, daily rain samples were collected at 4 locations in Minnesota using an automatic, refrigerated rain sampler. Based on the chemical composition of these samples, rain chemistry in Minnesota can be divided into three distinct types. Type 1: in mu eq/1, mean H+ 63; NO(3)- 54; SO(4) 125; NH(4):H+ 1.44. Type 2: in mu eq/1, mean H 36; NO(3)21; SO(4) 39; NH(4):HO.76. Type 3: in mu eq/1, mean H 2; NO(3) 64; SO(4) 100; NH(4):H 168. Branching trajectory analysis was performed to relate air parcel movement to the three types of rain chemistry. Type 1 chemistry was governed by long range transport of air parcels through the Ohio River Valley into Minnesota, plus the influence of Minneapolis-St. Paul urban plume. Type 2 chemistry was governed by air parcel movement from areas directly north of Minnesota. Type 3 chemistry was governed by long range transport from areas directly south of Minnesota, as far back as Texas. This air
movement was through the central agricultural areas of the U.S.
Impacts
(N/A)
Publications
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Progress 01/01/85 to 12/30/85
Outputs
A mixed, multivariate, polynomial, fourier model was developed to explain the relationships between changes in conifer tree growth and long term exposure to sulfur dioxide. The model parameters were estimated using the least squares approach. This model was verified using annual tree basal area increment data obtained at five locations downwind from a point source. The R values between the biological response and distance from the source closely followed the patterns of source plume diffusion. This model is unique in the sense that it does not use long term pollutant averages, but accounts for the time series and occurrences of individual pollutant episodes relative to biological response.
Impacts
(N/A)
Publications
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Progress 01/01/84 to 12/30/84
Outputs
The impacts of a scrubbed plume from a coalfired power plant on the terrestrial vegetation in the vicinity, were investigated over a period of 10 consecutive summers. Ground level sulfur dioxide concentrations at eight isopleths were mostly below 26 ug/mDT/hr and never exceeded 390 ug/mDT/hr. About 75% of the sulfate and nitrate in the rainfall was in a non-acid form, and was influenced by long range transport, as evidenced by back trajectory analysis. Vegetation in the vicinity of the source exhibited foliar sulfur accumulation due to the atmospheric inputs, for the first three years, after which it leveled off. The vegetation appeared to have compensated for the soil sulfur deficiency through atmospheric inputs. This was confirmed by using SDT, and boron as tracers of the source plume. No trends in soil chemistry were found during the 10 year period. Farming practices appear to be a more important factor in this context. The atmospheric sulfur inputs did not result
in crop productivity changes in soybean. On the other hand, the low sulfur dioxide inputs resulted in a reversal of the effects of ozone on soybean yield.
Impacts
(N/A)
Publications
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Progress 01/01/82 to 12/30/82
Outputs
Long range transport of air pollutants is estimated, through modeling, to contribute to roughly 80% of the ozone profiles in Minnesota. Minnesota soybean cultivars have been demonstrated to be sensitive to ozone. Therefore, the effects of ozone, sulfur dioxide or the mixture of the two pollutants were examined on soybean productivity under field conditions. A computerized open-top field chamber system was used to perform the experiment. The pollutant exposure regimes simulated the known ambient patterns in the study area. The results indicated that sulfur dioxide alone, at Minnesota concentrations and exposure regimes, produced no effect on soybean yield. On the other hand, exposures to ozone resulted in a 4% decrease in the yield. Combined exposures to the two pollutants resulted in a "less than additive" effect. Empirical modeling, using actual measured Minnesota ozone profiles and known plant responses, indicated a crop loss of 0.5 to 7.3% for alfalfa; 0 to
0.3% for corn; and 0 to 1.1% for wheat.
Impacts
(N/A)
Publications
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Progress 01/01/81 to 12/30/81
Outputs
Oxone, a constituent of photochemical smog, is a regional and an inter-regional problem in the U.S., It is also economically the most important phytotoxic air pollutant in the U.S. During summertime, ozone episodes frequently occur in Minnesota due to long range transport of air pollutants. Field surveys show ozone-induced visible injury on soybean in Minnesota almost every year. Soybean cultivars grown in Minnesota are generally of the indeterminate type. Many of these cultivars have not been Minnesota are generally of the indeterminate type. Many of these cultivars have not been previously examined for their response to ozone. For example, conformed well to a log-probability model with pollutant concentration and exposure time as the independent variables. Reduction in leaf chlorophyll concentration was correlated with visible injury. Several cultivars of soybean were screened for their response (visible injury or reduction in leaf chlorophyll) to ozone
exposures. Cultivars Cursoy and Vickory were most sensitive, Hodgson and Hodgson 78 were intermediate and Evans and Swift were comparatively tolerant. On the contrary, all of these cultivars did not exhibit visible injury to sulfur dioxide exposures of 0.4 ppm 2h/day/5 days.
Impacts
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Publications
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Progress 01/01/80 to 12/30/80
Outputs
Air Pollutions and Their Effects on Minnesota Vegetation. Summer of 1980 in Minnesota provided the most number of hourly ozone violations (roughly 500 hours) of the state air quality standard (0.07 ul/l/hr). Several soybean fields in Central Minnesota showed ozone injury symptoms. Each ozone episode was modelled for synoptic and local meteorology and reverse air parcel trajectories were developed. Individuals but separate episodes are dominated by the influence of long range pollutant transport or by Minneapolis-St. Paul. Most of the indeterminate cultivar of soybean grown in Minnesota appear to be ozone sensitive. Field Response of Soybean Cultivar Hodgson to Ozone, Sulfur Dioxide and the Mixtures. During the Summer of 1980 a large scale open-top chamber study was conducted to evaluate the joint, chronic effects of ozone/sulfur dioxide mixtures on yield. The pollutant exposures were computer controlled and roughly simulated the ambient conditions of Central
Minnesota. Ozone or sulfur dioxide singly, reduced the yield by roughly 12%. However, the pollutant mixtures produced a less than additive effect. With the mixture, yield was comparable to controls. This is a unique situation and should not be interpreted to mean that all ozone/sulfur dioxide mixtures would produce this effect on other soybean cultivars. This stress-response data is beong modelled towards understanding positive and negative effects of air polluntants on crop yield in Minnesota. Acidic rain and rain chemistry in Minnesota.
Impacts
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Publications
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Progress 01/01/79 to 12/30/79
Outputs
a. Air Pollutants and their Effects on Minnesota vegetation. Comparitively there were no serious ozone problems during 1979 Summer and thus, very little ozone-induced symptoms were observed on vegetation. Atmospheric modeling suggested that roughly 65% ozone is imported into Minn. during summer from out of state. Soybean and milk weed proved to be the most sensitive cultivated and native plant species respectively to ozone. Reverse air trajectory models were developed for the summer data of 1977 to pinpoint paths of air parcel movement to identify conditions that promote ozone import into Minnesota. This data is being analyzed at present. b. Response of Soybean Cultivars to Ozone and/or SO(2) Under Laboratory Conditions. Cultivars Cursoy, Vickery, Hodgson and Hodgson 78 are more sensitive to ozone in comparison to Evans and Swift. Minimum threshold for injury to Hodgson due to ozone is 0.08 ppm for 2 hours. However, Cursoy and Vickery may be even more sensitive.
Sulfur dioxide does not induce injury symptoms on Hodgson at 0.4 ppm for 4 hours. However, ozone and sulfur dioxide as a mixture (0.1 ppm and 0.4 ppm respectively for 4 hours) produce a more than additive joint effect. This is in studies where the same plant is exposed for 5 days successively to the said ones. The effect was evaluated as loss of chlorophyll. This is important relative to yield and is the first report of its kind in the literature. c. Acidic Rain and Rain Chemistry in Central Minnesota. The pH of rain varied from 3.76 to 7.90.
Impacts
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Publications
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Progress 01/01/78 to 12/30/78
Outputs
Air pollutants and their effects on Minnesota vegetation: Field surveys for air pollutant induced injury to cultivated and native vegetation were continued to evaluate the extent of the regional problem in Minnesota. Current evidence indicates that ozone is the largest problem relative to effects on plants. Evidence clearly demonstrated long distance transport of ozone from urban to rural areas. Response of soybean varieties to ozone and/or SO(2) under controlled environmental conditions. Dose response curves for ozone were developed for soybean cultivar Hodgson and high sensitivity to ozone was found. Chlorophyll reduction as a function of visible ozone injury was determined to quantify ozone injury. Does response curves to ozone are currently being constructed on soybean cultivar Hodgson 78, a new Hodgson line have resistance to Phytophthora root rot.
Impacts
(N/A)
Publications
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Progress 01/01/77 to 12/30/77
Outputs
Air Pollutants and their effects on Minnesota Vegetation. Three summers (including 1977) of field survey indicates ozone to be the most important regional problem in Minnesota. This is followed by sulfur dioxide at the local level around point sources. These studies constitute the first effort to assess air pollutant impacts on Minnesota vegetation and its potential significance. Long distance ozone transport from urban areas and impact on rural crop cultivation in Minnesota. Long distance transport of ozone and/or its precursors from the Minneapolis St. Paul to rural areas has been documented. Two summers of soybean yield studies relative to air quality (ozone transport) has been completed. While during the summer of 1976 24% yield reduction in soybean var. Hodgson was seen due to air pollutants, during the summer of 1977 no such reductions were observed. No ozone episodes occurred during the 1977 summer at the field study site. Response of soybean varieties
to ozone under controlled environment. Soybean var. Chippewa 64 has been screened and dose-response curves for ozone developed. Preliminary comparisons show that variety Hodgson is more sensitive than Chippewa 64 to ozone. Variety Hodgson is planted widely in Minnesota at this time.
Impacts
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Publications
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Progress 01/01/76 to 12/30/76
Outputs
Air pollution - impacts on Minnesota vegetation: Based on summer air quality and weather data, evidence was obtained to show long distance transport to ozonefrom Minneapolis-St. Paul in a north-northwest direction. Visible ozone-inducedinjury was recorded on field grown soybean in this direction up to approximately45 miles from the Twin Cities. Preliminary data suggests that there may be a significant reduction in the soybean yield in this area. Influence of ozone on biopathogen-induced plant disease: Exposure to appropriate doses of ozone inhibited the incidence of common bacterial blight on soybean. The same effect was observed with reference to the incidence of rust on bean. Inversely in neither case, infection by the biopathogen induced plant resistance to ozone. Pollution in rain: Eight automatic-sequential rain sampling systems were established around a coal-fired power plant in central Minnesota. Rain analysisdata from the summer of 1976 confirmed that both
strong and weak acids coexist in rain.
Impacts
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Publications
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Progress 07/01/75 to 12/30/75
Outputs
Air pollution - impacts on Minnesota vegetation: Several important plant pathogenic air pollutants, their sources or location of generation in Minnesota identified, preliminary field vegetational injury survey completed. Some examples of injury: soybean, bean-ozone; aspen, birch, pine - sulfur dioxide, fluoride; lilac, wheat - particulates; cucumber, tomato, maple, aspen - acid aerosol; beet, tomato - ammonia. Influence of ozone on biopathogen induced plant disease: Exposure of bean to ozone can modify incidence of alfalfa mosaic on that host. The virus disease is stimulated or inhibited depending upon whether host was first exposed to virus or to ozone. Leaves applied with 0.2M sodium phosphate or copper sulfate prior to ozone exposure are protected againstthe air pollutant. Pollution in rain: Twin Cities rain in general is acidic. Some acidity is due to anthropogenic activity and the rest may be natural. At least 5 chemical species of compounds contribute to
rain acidity. Current projections of acidic rain effects on vegetation may not be wholly correct. An automatic, battery operated, sequential rain sampler was developed to collect rain around pollution sources, to help understand rain chemistry and vegetational effects. This rain sampler by far is the most sophisticated collector currently available. For the first time evidence was obtained to showthat gaseous compounds may contribute as much as non-gaseous compounds towards rain acidity. Furthermore gaseous material constitutes weak acids in
Impacts
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