Figure S2 Indicator OTUs from the first experiment were consistent for occupants regardless of sampling method. Eight of these ten OTUs were also significant indicator taxa included in Table 3.
At the level of the individual thallus, acidity affects nitrogen fixation, photosynthesis, growth, and cellular ultrastructure Belnap et al. Besides these direct effects on physiological processes, environmental acidity can affect cryptogamic communities indirectly by altering substrate chemistry, thereby affecting species diversity and composition at the community level.
Bark pH interactions Ecological studies of epiphyte communities have shown that, even in unpolluted areas, natural variations in bark chemistry have a major impact on which species are present Farmer, et al. For example, Hale found that species of Physcia, Xanthoria, and Candelaria were more common on trees with bark pH values of 5.
Many factors can influence bark pH. Tree species differ in this characteristic; for instance, conifers generally have lower bark pH than angiosperms. Other influential factors affecting the number and type of epiphytes present include the buffering capacity of the bark, dust accumulation, and the age of tree.
Individuals of a single tree species can have markedly different bark chemistries and epiphyte communities Farmer et al. For example, Gilbert showed that the pH of Fraxinus could vary on a single tree from 5. Gough speculated that continuous peeling off of bark scales may be one reason for little epiphytic cover on Pinus ponderosa in Colorado.
He found that P. Distribution of lichens on trees may also be related to pH. The pH of the outermost newly-exposed orange bark of trees over 4 dm in diameter tended to be significantly lower pH 3.
The pH of bark on twigs averaged about 4. The presence of pollutants also affects bark pH. Gilbert studied the pH of the bark of Fraxinus excelsior and Acer pseudoplatanus in and around Newcastle. While the average pH value of F. Robinia psuedoacacia trees growing in the vicinity of a pulp mill Hoffman were found to have bark pH values of 6.
The primary aim of the partial-depth spall repair study was to determine the most effective and economical materials and procedures for placing quality, long-lasting partial-depth patches in jointed concrete pavements. Portland Cement Concrete (PCC) Partial-Depth Spall Repair. Experiment Design Beginning in March , more than. Since the objective of the first experiment was to determine the detectability of a single occupant in a cleaned room, we first focused on differentiating occupied air from unoccupied. Human occupants shed a detectable bacterial cloud. An atomic clock is a clock device that uses an electron transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a .
British researchers have noted that bark pH is a critical factor in the establishment of acidophilous species of the Parmelia laevigatae community, normally associated with high elevation woodlands. With continuing acidification these species can replace the lower elevation Lobaria community.
Acid rain can reduce pH of both tree bark and lichen thalli Farmer et al. Soil chemistry interactions Variations in soil chemistry may be important.
For example, Norwegian oaks with Lobarion species grew mainly on nutrient rich soils. Variations in bark chemistry may be affected by variations in soil cation availability.
The relationship between soil and bark chemistry is further complicated by the ability of trees with acidic stemflow to acidify the surrounding soil, as demonstrated for Fagus sylvatica in Sweden Farmer et al, For epiphytes, extreme events are evened out by the buffering capacity of bark, so that the best predictions of epiphyte response are probably made on annual averages of pollutant loading.
Lichens may respond to short episodic pollution events within a local area that may be undetected by conventional analysis. Other substrate interactions Evidence from field observations, intensive studies of the environment at contrasting sites, and field and lab experiments Farmer et al.
In addition, when pollution occurs in poorly buffered environments, species such as Lobaria which normally thrive on mildly acidic to neutral substrate, will also be negatively affected Farmer et al.
Desert lichens, which obtain most of their water from fog and dew, are particularly vulnerable to air quality and weather pattern changes FollmanNash Sensitivity of lichens to sulfur dioxide vs.
Nitrogen enriched acid rain The nitrogenous component of acid rain can produce a fertilizer effect on lichens and cause floristic changes. In unpolluted areas, tissue levels were 0. However, the problem of defining critical loads for nitrogen has not been resolved. Lichen structure and physiology The effects of acid rain on lichen structure and physiology include a decrease in nitrogen fixation, photosynthesis, and growth, and changes in cellular ultrastructure Belnap et al.
They found reduced photosynthesis and chlorophyll levels, and decreased dry weight and podetial height of thalli of both species receiving pH 2. No effects were observed at pH 3 and above.Sep 22, · Since the objective of the first experiment was to determine the detectability of a single occupant in a cleaned room, we first focused on differentiating occupied air from unoccupied.
Human occupants shed a detectable bacterial cloud. The primary aim of the partial-depth spall repair study was to determine the most effective and economical materials and procedures for placing quality, long-lasting partial-depth patches in jointed concrete pavements.
Portland Cement Concrete (PCC) Partial-Depth Spall Repair. Experiment Design Beginning in March , more than. State of Oregon Department of Environmental Quality Oregon Annual Ambient Criteria Pollutant Air Monitoring Network Plan Submitted to: Environmental Protection Agency, Region monitoring allows DEQ to determine air toxics levels.
DEQ routinely assesses air toxics in communities statewide and has done air toxics monitoring in Portland, Beaverton, Salem, Medford and La Grande.
For more information about air toxics, please see Air Quality Specialist Eastern Region DEQ SE Emigrant # Pendleton, OR Sep.
25, — Outdoor air pollution is a major contributor to indoor air pollution -- but high-efficiency particulate air (HEPA) filters used in the home significantly reduce fine-particulate. The U.S. Environmental Protection Agency set national air quality standards for six common pollutants (also referred to as "criteria" pollutants).