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An increase in quarrying, open-cast mining and road traffic suggest that dust deposition onto vegetation may be increasing. This review describes the physical and chemical characters of a range of dust types. The effects of dust on crops, grasslands, heathlands, trees and woodlands, arctic bryophyte and lichen communities are identified. Dust may affect photosynthesis, respiration, transpiration and allow the penetration of phytotoxic gaseous pollutants. Visible injury symptoms may occur and generally there is decreased productivity. Most of the plant communities are affected by dust deposition so that community structure is altered. Epiphytic lichen and Sphagnum dominated communities are the most sensitive of those...
Concern over impacts of atmospheric nitrogen deposition to ecosystems in Rocky Mountain National Park, Colorado, has prompted the National Park Service, the State of Colorado Department of Public Health and Environment, the Environmental Protection Agency, and interested stakeholders to collaborate in the Rocky Mountain National Park Initiative, a process to address these impacts. The development of a nitrogen critical load for park aquatic resources has provided the basis for a deposition goal to achieve resource protection, and parties to the Initiative are now discussing strategies to meet that goal by reducing air pollutant emissions that contribute to nitrogen deposition in the Park. Issues being considered...
Only a minor part of the absorbed global radiation by plant leaves is used in photosynthesis. The rest is converted into sensible heat influencing energy balance and temperature of leaves. Dust cover on leaves increases their absorptivity and an increase of leaf temperature influencing productivity of the plants is to be expected. Spectral properties and temperatures of leaves covered with road dust and identical but clean leaves were measured. Absorptivity of dusty leaves is more than doubled for the waverange 700 to 1350 nm. Temperatures of dusty leaves are 2 to 4�C higher than those of clean leaves. Absorbed incident global radiation was calculated in order to discover which waverange of incident radiation caused...
An increase in quarrying, open-cast mining and road traffic suggest that dust deposition onto vegetation may be increasing. This review describes the physical and chemical characters of a range of dust types. The effects of dust on crops, grasslands, heathlands, trees and woodlands, arctic bryophyte and lichen communities are identified. Dust may affect photosynthesis, respiration, transpiration and allow the penetration of phytotoxic gaseous pollutants. Visible injury symptoms may occur and generally there is decreased productivity. Most of the plant communities are affected by dust deposition so that community structure is altered. Epiphytic lichen and Sphagnum dominated communities are the most sensitive of those...
We evaluated the effects of livestock grazing on C content of the plant?soil system (to 60 cm) of two semi-arid grasslands: a mixed-grass prairie (grazed 12 years), and a short-grass steppe (grazed 56 years). Grazing treatments included season-long grazing at heavy and light stocking rates, and non-grazed exclosures. Significantly higher soil C (0?30cm) was measured in grazed pastures compared to non-grazed exclosures, although for the short-grass steppe higher soil C was observed with the heavy grazing treatment only. Excluding grazing caused an immobilization of C in excessive aboveground plant litter, and an increase in annual forbs and grasses which lack dense fibrous rooting systems conducive to soil organic...
An increase in quarrying, open-cast mining and road traffic suggest that dust deposition onto vegetation may be increasing. This review describes the physical and chemical characters of a range of dust types. The effects of dust on crops, grasslands, heathlands, trees and woodlands, arctic bryophyte and lichen communities are identified. Dust may affect photosynthesis, respiration, transpiration and allow the penetration of phytotoxic gaseous pollutants. Visible injury symptoms may occur and generally there is decreased productivity. Most of the plant communities are affected by dust deposition so that community structure is altered. Epiphytic lichen and Sphagnum dominated communities are the most sensitive of those...
The effects of elevated metals (dissolved Zn, Mn and/or Fe) in a Rocky Mountain stream were assessed using measures of primary productivity, community respiration and water-column toxicity. Primary productivity was measured as rates of O2 evolution from natural substrates incubated in situ in closed chambers. Oxygen depletion within these chambers, when incubated in the dark, provided estimates of periphyton community respiration. Sediment community respiration on fine-grained sediments, collected and composited along each stream study reach, was measured on-site by incubating these sediments in closed chambers and measuring O2 depletion. Toxicity was measured as percent mortality of Ceriodaphnia dubia during 48...
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The exposure of white-footed mice (Peromyscus leucopus) to lead and cadmium and the potential associated toxic effects were examined at three sites contaminated with lead in the Southeast Missouri Lead Mining District and at a reference site. Mice from the contaminated sites showed evidence of oxidative stress and red-blood cell δ-aminolevulinic acid dehydratase (ALAD) activity was depressed by an average of 68% at the most contaminated site. However, histological examinations of the liver and kidney, cytologic examination of blood smears and biomarkers of lipid peroxidation and DNA damage failed to show evidence of toxic effects from lead. The biomagnification ratio of cadmium (hepatic concentration/ soil concentration)...
Environmental pollution has a major effect on human health and other life types. A source of environmental pollution is the magnetic field produced near high and extra high voltage (EHV) transmission lines. Magnetic fields from AC EHV lines have been discussed in this paper. The field profiles and their contribution to environmental pollution are studied, these being under transmission lines with different line system configurations, using the three dimensional approaches. These line system configurations are more commonly used in Egypt and other countries. The obtained results are found to be useful for discussing the comparison of the field densities on the human body and other life types at the ground level under...
In the absence of human activities, biological N fixation is the primary source of reactive N, providing about 90–130 Tg N year−1 (Tg = 1012 g) on the continents. Human activities have resulted in the fixation of an additional 150 Tg N year−1 by energy production, fertilizer production, and cultivation of crops (e.g., legumes, rice). Some sinks of anthropogenic N have been estimated (e.g., N2O accumulation in the atmosphere; loss to coastal oceans), however due to the uncertainty around the magnitude of other sinks (e.g., retention in groundwater, soils, or vegetation or denitrification to N2) a possibly large portion of the N fixed by humans is missing. While we know that N is accumulating in the environment,...
The Rocky Mountains of Colorado and southern Wyoming receive atmospheric nitrogen (N) deposition that ranges from 2 to 7 kg ha?1 yr?1, and some previous research indicates pronounced ecosystem effects at the highest rates of deposition. This paper provides a critical review of previously published studies on the effects of atmospheric N deposition in the region. Plant community changes have been demonstrated through N fertilization studies, however, N limitation is still widely reported in alpine tundra and subalpine forests of the Front Range, and sensitivity to changes in snow cover alone indicate the importance of climate sensitivity in these ecosystems. Retention of N in atmospheric wet deposition is <50% in...
    map background search result map search result map Exposure of Peromyscus leucopus to lead and cadmium in the Southeast Missouri Lead Mining District Exposure of Peromyscus leucopus to lead and cadmium in the Southeast Missouri Lead Mining District