Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 21 for “"acid deposition"”.
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Acid deposition in the Eastern Transvaal Highveld
… has been placed on the severity of atmospheric deposition despite the fact that acid deposition is a major world-wide environmental concern. This study focusses on the chemistry and severity of atmospheric depositions to the south and south-east of the Witbank-Middleburg Power and Industrial …
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Modeling the Effects of Acid Deposition and Natural Organic Acids on Surface Waters
<p>Atmospheric deposition of sulfuric and nitric acids has impacted surface waters in the eastern U.S. Controls on anthropogenic S and NOx emissions have resulted in a substantial decrease in acid deposition. Long-term measurements of surface water chemistry indicate contrasting responses of …
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Acid deposition effects on soil chemistry and forest growth on the Monongahela National Forest
Acid deposition (AD) results largely from the combustion of fossil fuels, and has been found to negatively impact forest ecosystems. AD may acidify soils through base cation leaching or Al mobilization, may cause accumulation of nitrates and sulfates in soils, and in some cases has been related to …
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An Integrated Modeling Approach for the Study of the Impacts of Acid Deposition Control Regulations
Acid deposition has become a serious environmental problem in the last decade. The economic repercussions of acid deposition control regulations give rise to interregional and international conflicts as to who is to bear the burden of its abatement. Responsive policy decisions have to be based on …
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Effects of Acid Deposition and Changing Climate on the Hydrochemistry and Critical Loads of Watersheds in the Adirondack Region of New York
<p>Despite decreases in acidic deposition since the 1970s, the recovery of surface waters from acidification has been limited primarily due to the depletion of exchangeable base cations, net mineralization of organic sulfur and nitrogen and release of previously retained SO42- and NO3-, and …
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The impact of plantations of Pinus spp. on the chemical properties of soils and stream waters in South African upland catchments
… constitute a significant component of the acid load to forest soils and can result in significant decreases in soil pH, acid neutralising capacity and base status. Despite this, the possibility that these processes can result in a significant transfer of acidity to drainage solutions and …
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Quantifying the Responses of Vegetation to Environmental Stresses
… and addressed the effects of drought and acid deposition on plant water use. Using a novel stable isotope technique, I showed that plant water source utilization can be modulated in some species based on the soil and atmospheric conditions they experience, whereas others only access a …
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Effects of nitrogen and calcium on photosynthesis and metabolic activity in Acer saccharum in the Catskill Mountains
… southern New York have received some of the most acidic rainfall in the country for the past 50 years. Acid deposition on these thin soils may deplete the concentration of calcium and other essential ions in the soil solution and mobilize other ions that can be harmful to sugar maple (Acer …
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Ecology of acidification and recovery in Welsh upland streams
This study investigates the current impact of acid deposition on the structure and function of benthic communities in streams of contrasting pH in mid-Wales, UK, and examines barriers to biological recovery across the sites. The results of field surveys across 30 streams revealed sustained effects …
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Air Pollutant Concentrations and Trends over the Eastern U.S. and China: Aircraft Measurements and Numerical Simulations
… caused severe environmental issues including acid deposition and particulate matter pollution. To mitigate these air quality problems, strict control measures and regulations were applied to abate sulfur emissions, especially before and during the 2008 Beijing Olympics. Aircraft measurements …
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Linking Carbon, Nitrogen, And Calcium Cycling In Northeastern U.S. Forests
… been dramatically altered by human activities. Acid deposition has increased N inputs and caused declines in soil Ca concentrations. Concurrently, atmospheric carbon dioxide concentrations are rising. My dissertation research focused on understanding how individual tree species influence …
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Dissolved organic matter dynamics in diverse freshwater ecosystems across Canada: long-term trends, transformations, and explanatory factors
… have documented the influence of recovery from acidification and climate change on long-term DOC trends, the emerging importance of these explanatory factors remains less understood. In addition, few studies have followed up on recent trends in sites that have undergone increases in DOC. Using a …
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Development of soil lead and tree-ring methods for characterizing atmospheric deposition gradients and subsequent tree growth responses
Atmospheric deposition of pollutants and nutrients can have a range of effects on aquatic and terrestrial ecosystems. Despite its ecological importance, it remains a challenge to model patterns of deposition across complex terrain and also to assess how forest ecosystems are reacting to chronic …
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Assessment of air pollution impacts on vegetation in South Africa
… of Cape Town. Gaseous air pollutants, including acid deposition and acidic mist, probably play a major role in the development of characteristic air pollution injury symptoms observed on pine trees in the Eastern Transvaal area. The impact of urban air pollution in the Cape Town area was …
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A method for correlation of gravestone weathering and air quality (SO2), West Midlands, UK
… quality primarily from particulate matter and acid in the form of NOx and SOx compounds. Air quality stations across the region recorded SO2 beginning in the 1960s however the direct measurement of air quality prior to 1960 is lacking and only anecdotal notations exist. Proxy records including …
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THE EFFECTS OF WHOLE TREE HARVESTING ON SITE HYDROLOGY AND SOIL STRUCTURE AT BEDDGELERT FOREST, N. WALES, UK
… for the solute chemistry and movement of acid deposition in that soil water born solutes will tend to enter water courses more rapidly than if vertical flow predominated.
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Sulfate Dynamics and Base Cation Release in a High Elevation Appalachian Forest Soil
… terms of their susceptibility to enhanced soil acidification via acidic atmospheric inputs. After initial physical, chemical, and mineralogical characterization, the soils were analyzed for their ability to adsorb and retain sulfate (SO₄²⁻) through a series of batch adsorption and desorption …
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Quantifying macroinvertebrate structural and functional response to stream acidification and subsequent recovery in Shenandoah National Park
Acid rain alters freshwater pH and ion composition, preventing organisms from performing essential bodily functions causing mortality. Macroinvertebrate communities in acidified streams are characterized by species loss in response to physiological stress and altered food quality resulting from the …
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NATURALLY ACIDIC OR ANTHROPOGENICALLY ACIDIFIED? UNCOVERING THE DRIVERS OF STREAM ACIDITY DURING STORMFLOW IN THE NEE SOON CATCHMENT, SINGAPORE
Episodic acidification occurs as periods of high flow temporarily reduce the streams’ acid neutralizing capacity (ANC). In Singapore, the acidification of streams in the Nee Soon Swamp Forest (NSSF) is thought to have deleterious impacts on aquatic ecosystems. This research aims to understand …
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