Andrzej Bytnerowicz

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.

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.

Effects of photochemical smog and mineral nutrition on ponderosa pine seedlings

Two-year-old seedlings of ponderosa pine (Pinus ponderosa Dougl. ex Laws) were exposed to ambient concentrations of photochemical smog (AA) and clean air (CA) during a single field season at Tanbark Flat of the San Gabriel Mountains in the Los Angeles Basin. The seedlings were grown in a perlite-vermiculite medium with full supply of nutrients (based on modified Hoagland solution); reduced to 50% supply of N; reduced to 50% supply of Mg; and reduced to 50% supply of N+Mg. No significant effects of air pollution exposures on injury development, stem growth and concentrations of plant pigments were determined. The seedlings in the AA treatment had decreased N concentration in current year needles compared with CA seedlings; however, the needle concentrations of other elements did not change. Reduction of N supply in the growing medium caused decreased N, P, Ca, K and chlorophyll a concentrations in needles. Stem growth of the seedlings with reduced N supply was significantly decreased as well. No changes in stem growth or chemical composition of plants with reduced Mg supply were noted. Reduction of supply of nutrients did not change responses of trees to the air pollution exposures.

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.

Interactive effects of simulated acidic fog and ozone on field-grown alfalfa

Abstract Acid precipitation events, primarily in the form of fogs with pH as low as 2.0, have been reported from both urban and agricultural areas of California. If low pH acidic precipitation increased stomatal conductance, flux of gaseous air pollutants into mesophyll spaces could increase, thereby increasing susceptibility of plants to air pollution injury. The potential for this interaction is acute in California because of high ambient ozone (O3) levels present in areas frequently subjected to fogs. A field experiment was conducted to determine the interactive effects of simulated acidic fog and O3 on stomatal conductance, photosynthesis, foliar injury, and yield of an established stand of alfalfa (Medicago sativa L.). Plants were exposed to five levels of O3 for 12 hr daily for 4 weeks. Ozone was added in proportion to its concentrations in ambient air. Levels ranged from 1 4 of ambient to twice ambient concentrations. Simulated fog solutions of pH 2.0, 3.2, 4.4, and 5.6 acidified with 2:1 HNO3:H2SO4 were applied from 0300 to 0500 three times per week for 4 weeks. Treatments were replicated twice. Alfalfa was harvested when plants were at 1 10 bloom stage and crown sprouts exceeded 4 cm in length. Results indicated that both stomatal conductance and photosynthesis decreased with increasing acidity of fog. Foliar injury attributable to acid deposition was observed only in the pH 2.0 fog treatment. Alfalfa yield was significantly reduced by both acid fog and O3, but the interaction between the two was not statistically significant. The threshold for significant growth reduction in alfalfa exposed to simulated fog in open-top chambers was pH 2.0 and pH 3.2 for alfalfa in ambient-air plots.

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...

Injury and physiological responses of Larrea tridentata (DC) coville exposed In situ to sulphur dioxide

The response of shrubs of Larrea tridentata (DEC) Coville (creosotebush) exposed to sulphur dioxide (SO(2)) was evaluated using in situ plants of the Majove Desert. Larrea was exposed to acute levels of 0.3 to 2.0 microl litre(-1) SO(2) for periods up to 13 days using field chambers or an open-air fumigation system. Plants exposed in the spring exhibited considerable leaf injury (necrosis and defoliation) when exposed to 2.0 microl litre(-1) SO(2), and in the autumn had leaf injury when exposed to >0.4microl litre(-1) SO(2). Injured plants had higher transpiration rates, less negative water pressure potentials, and/or lower photosynthetic rates than control plants. It is likely that Larrea would not be injured by the typically low SO(2) concentrations and dry environmental conditions of the Mojave Desert. However, if injury were to occur, it would be accompanied by changes in plant-water relations and photosynthesis, followed by recovery after the SO(2) stress was removed.