David M. Olszyk

Emission rates of organics from vegetation in California's Central Valley

Rates of emission of speciated hydrocarbons have been determined for more than 30 of the most dominant (based on acreage) agricultural and natural plant types found in Californias Central Valley. These measurements employed flow-through Teflon chambers, sample collection on solid adsorbent and thermal desorption gas chromatography (GC) and GC-mass spectrometry analysis to identify more than 40 individual organic compounds. In addition to isoprene and the monoterpenes, we observed sesquiterpenes, alcohols, acetates, aldehydes, ketones, ethers, esters, alkanes, alkenes and aromatics as emissions from these plant species. Mean emission rates for total monoterpenes ranged from none detected in the case of beans, grapes, rice and wheat, to as high as 12–30 μg h−1 g−1 for pistachio and tomato (normalized to dry leaf and total biomass, respectively). Other agricultural species exhibiting substantial rates of emission of monoterpenes included carrot, cotton, lemon, orange and walnut. All of the plant species studied showed total assigned compound emission rates in the range between 0.1 and 36 νg h−1 g−1.

Gaseous and particulate air pollution in the San Gabriel Mountains of Southern California

In order to assess concentrations and daily patterns of air pollutants at a mountainous site in the South Coast Air Basin, a study was undertaken in the San Dimas Experimental Forest of the San Gabriel Mountains between April 1985 and October 1985. Continuous monitoring of O3, NO, NO2, SO2, total S compounds and light scattering coefficient was conducted. Particulate aerosols were collected twice a week and concentrations of nitrate, ammonium and sulfate in fine ( 2.5 μm diameter) modes were determined. For the June–August period, when the levels of photochemical smog were the highest, monthly 24-h average concentrations of the pollutants were: O3, about 200 μg m−3; NO2, 40–75 μg m−3; NO, 1–5 μg m −3; and SO2, 0.5–5 μgm−3. The concentrations of O3 were about two times higher than in the neighboring stations of the South Coast Air Basin. O3, SO2 and total S concentrations peaked in the early afternoon, generally between 1500 and 1600 PST. Peak concentrations of NO occurred in the morning, generally between 1000 and 1100 PST. NO2 concentrations typically peaked in the late afternoon between 1500 and 1800 PST, but occasionally (in 9 % of days) maximum NO2 occurred in the morning, concurrently with the NO peaks. Daytime concentrations of the nitrate in fine aerosol fraction were generally between 100 and 600 nEq m −3, those of ammonium between 50 and 300 nEq m −3, and concentrations of sulfate between 60 and 250 nEq m−3. A 3-day denuder study showed that HNO3can make up to 73 % of the total amount of total nitrate in the air. NO2 was the most abundant N compound at Tan bark Flat (69–86% of the total amount of the monitored N compounds). Nitrate amounted to 9–15 %, HNO3 to 4–11 %, ammonium to 3–9%, and NO to 1–2% of the total amount of the measured nitrogen compounds.

Dry deposition of nitrate, ammonium and sulfate to a Ceanothus crassifolius canopy and surrogate surfaces

Deposition of nitrate (NO3−), ammonium (NH4+) and sulfate (SO42− to the foliage of Ceanothus crassifolius and surrogate surfaces was studied in the San Dimas Experimental Forest, 35 km northeast of central Los Angeles. Deposition fluxes of NO3− and NH4+ to the foliage were found to be well correlated with deposition fluxes to nylon fillers, but not the deposition fluxes to polycarbonate Petri dishes. Deposition fluxes of SO42− to the foliage correlated better with deposition fluxes to polycarbonate Petri dishes than to nylon filters. Deposition fluxes of NO3− to all the studied surfaces were higher than fluxes of NH4+ and SO42−. Comparison of NO3−:NH4+: SO42−ratios of deposition fluxes to different surfaces indicated a much higher importance of N than S species in the total load of dry deposition to the chaparral foliage canopy in the South Coast Air Basin. These ratios are quite different from those found in Tennessee and West Germany, where sulfate has been reported to be the main component of dry deposition to plant canopies. Deposition fluxes of NO3−, NH4+and SO42− to nylon filters and Petri dishes increased with height of placement above the chaparral canopy.

Effects of ozone or sulfur dioxide on growth and yield of rice

Abstract Three cultivars of rice, Oryza sativa, M7, M9 and S201 were exposed in open-top field chambers to ozone and sulfur dioxide to determine the effects of these important air pollutants on field-grown plants. Exposures were for 15 weeks with ozone at 0, 98, 196, 294 or 392 μg m−3 for 5 h day−1, 5 days week−1, and sulfur dioxide at 131, 262, 393 or 524 μg m−3 for 24 h day−1, 5 days week−1. Three harvests of rice were made after 27 and 68 days and at the end of the exposures. At the first harvest following early plant growth, ozone at the highest concentrations resulted in reductions in growth whereas sulfur dioxide resulted in increased growth. At the second harvest, ozone-exposed plants continued to show reduced growth, whereas sulfur dioxide resulted only in reduced plant height. At the final and major harvest, ozone at 392 μg m−3 reduced total seed weight 12, 29 and 21% in cultivars M7, M9 and S201, respectively. Weight of 100 seeds and straw weight were reduced in M9 and S201 and percent seed sterility in panicles was increased. Ozone reduced height of all cultivars and increased the number of panicles. Sulfur dioxide at 524 μg m−3 reduced total seed weight of M9 and S201 by 22 and 14%, respectively, and weight per hundred seed by 11 and 10%, respectively. The results showed that ozone is much more injurious to rice per unit of pollutant than sulfur dioxide and that reduced yield due to both pollutants was caused mostly by reduced seed size. Increased seed sterility was partially offset by ozone exposure of the plants which produced more panicles. Cultivar M7 was more resistant to ozone or sulfur dioxide than M9 and S201.

Crop loss assessment for California: modeling losses with different ozone standard scenarios.

Crop yield losses were estimated for ambient O3 concentrations and for a series of potential O3 air quality standards for California, including the current statewide 1-h oxidant (O3) standard of 0.10 ppm (196 microg m(-3)), 12-h growing season averages, and other models. A model for statewide losses was developed using hourly O3 data for all sites in the State, county crop productivity data, and available O3 concentration-yield loss equations to determine potential yield losses for each crop in each county in California for 1984. Losses were based on comparison to an estimated background filtered air concentration of 0.025 or 0.027 ppm, for 12 or 7 h, respectively. Potential losses due to ambient air in 1984 were estimated at 19% to 25% for dry beans, cotton, grapes, lemons, onions, and oranges. Losses of 5% to 9% were estimated for alfalfa and sweet corn. Losses of 4% or less were estimated for barley, field corn, lettuce, grain sorghum, rice, corn silage, spinach, strawberries, sugar beets, fresh tomatoes, processing tomatoes, and wheat. Implementation of either a modified rollback to meet the current 1 h California O3 standard (0.10 ppm) or a three-month, 12-h growing season average of 0.045 ppm was necessary to produce large reductions in potential crop losses.

Effects of SO2 on physiology, elemental content and injury development of winter wheat

Abstract The effects of sulfur dioxide on buffering capacity, chlorophyll content, stomatal conductance, mineral composition and leaf injury of winter wheat ( Triticum aestivum , cv. Yecora Rojo) were studied. Plants were exposed to sulfur dioxide (0, 79, 183, and 393 μg m −3 ) in open-top chambers. Exposures were conducted in Riverside, California, during the coolest part of the year when the plants are believed to be more sensitive to sulfur dioxide than during the rest of the year. Physiological measurements, injury rating and collection of leaf material for chemical analysis were carried out after 22 days of exposure. The results of these measurements were compared with yield data from the final harvest which took place after 118 days of exposure. Elevated SO 2 concentrations caused decrease of buffering capacity, increase of total sulfur content and increase of injury of wheat leaves. These changes correlated significantly with reduction of total seed weight and weight of 100 wheat seeds at the final harvest. Stomatal conductance to water vapor, chlorophyll content and two leaf mineral concentrations (calcium, potassium) were not significantly affected by sulphur dioxide exposure. The results of this study indicated that buffering capacity, total sulfur content and injury of leaves could be used as early indicators of SO 2 stress in wheat and its subsequent yield losses.

Open Top Experimental Chambers for Trees

A large, relatively light weight open top experimental chamber was designed, constructed, and tested at the University of California, Riverside. The chamber used the essential basic design principles incorporated into the National Crop Loss Assessment Network chambers. However, because of its unique application for trees, the chambers structural characteristics are basically of original design. This report describes chamber design, construction, and performance characteristics based on 15 months of operation. The chambers are in use and will continue in operation until the fall of 1986. 5 references, 7 figures, 1 table.

Leaf photosynthetic and water-relations responses for 'Valencia' orange trees exposed to oxidant air pollution

Abstract Leaf responses were measured to test a hypothesis that reduced photosynthetic capacity and/or altered water relations were associated with reductions in yield for “Valencia” orange trees (Citrus sinensis [L.], Osbeck) exposed to ambient oxidant air pollution. Exposures were continuous for 4 years to three levels of oxidants (in charcoal-filtered, half-filtered, and non-filtered air). Oxidants had no effect on net leaf photosynthetic rates or on photosynthetic pigment concentrations. A single set of measurements indicated that oxidants increased leaf starch concentrations (24%) prior to flowering, suggesting a change in photosynthate allocation. Leaves exposed to oxidants had small, but consistent, changes in water relations over the summer growing season, compared to trees growing in filtered air. Other changes included decreased stomatal conductance (12%) and transpiration (9%) rates, and increased water pressure potentials (5%). While all responses were subtle, their cumulative impact over 4 years indicated that “Valencia” orange trees were subject to increased ambient oxidant stress.

Physiological responses of field-grown strawberry (Fragaria × Ananassa duch.) exposed to acidic fog and ambient ozone

Abstract Physiological responses of field-grown strawberry ( Fragaria × ananassa Duch. Chandler) were monitored to examine the mechanistic basis of acidic fog and ambient ozone (O 3 ) impacts on growth and yield. Strawberry plants were exposed to simulated fog (pH 7.24, 2.69, or 1.68) twice weekly for 11 weeks, singly or in combination with ambient levels of O 3 in open-top field chambers. Applications of highly acidic fog (pH 1.68) caused significant reductions in growth, but leaf gas exchange process rates on a leaf area basis were not significantly affected despite the development of interveinal necrosis. However, calculated rates of whole-plant photosynthesis were associated with the observed negative impacts of pH 1.68 fog on vegetative growth. In contrast, plants grown in ambient O 3 (whole-study 12 hr average of 66 ppb) exhibited no significant alterations in growth, but yields were higher than in plants exposed to charcoal-filtered air. Exposure to ambient O 3 induced depressions in leaf gas exchange on a unit areas basis (i.e. net photosynthesis, stomatal conductance of water vapor, and transpiration), but calculated whole-plant photosynthesis was similar in charcoal-filtered air and O 3 -exposed plants due to differences in leaf area per plant (i.e. 14% higher in O 3 -exposed plants). It is concluded that acidic fog-induced alterations in strawberry growth were predicated upon the development of extensive foliar injury leading to the inhibition of whole-plant photosynthesis. However, in O 3 -exposed plants, whole-plant photosynthetic rates were conserved, suggesting that impacts on assimilate partitioning may play a more prominent role.

Responses of Desert Annual Plants to Ozone and Water Stress in an in situ Experiment

Desert winter annual plants: Camissonia claviformis, C. hirtella, Caulanthus cooperi, Chaneactis carphoclinia, C. stevioides, Cryptantha angustifolia, C. pterocarya, Erodium cicutarium, Festuca octoflora, Lupinus concinnus, Oenothera californica, Plantago insularis, Platystemon californica, Salvia columbariae, Thelypodium lasiophyllum, and Thysanocarpus curvipes growing on irrigated and non-irrigated plots were exposed in situ to elevated levels of ozone dispensed from an open air exposure system. Plants were exposed intermittently to a gradient of ozone of concentrations ranging between 44 and 133 ppb (nL L−1) for 35 h over a total of 216 h. Only three species were injured by ozone at the highest ozone concentrations. Leaf injury to C. claviformis—2 percent total foliar injury (TFI), C. hirtella—1 percent TFI, and Erodium cicutarium—2 percent TFI, developed at the highest ozone concentrations. Leaf injury to these species was similar on the irrigated and nonirrigated plots. Leaf water potential and stoma...