Acid Deposition

The risk of soil acidification is high in the Athabasca oil sands region (AOSR) in Alberta, Canada, due to elevated SO2 emission and the resultant acid deposition to sensitive, coarse-textured soils. Understanding the sulfate adsorption characteristics of soils sensitive to acidification will help establish critical loads of acid deposition in AOSR. Sulfate adsorption properties were evaluated and relationships between sulfate

Sri Lanka has an exceptionally rich amphibian biodiversity with high endemism. This paper describes 106 amphibian species, the majority confined to rainforests and many threatened with extinction. The key factors causing amphibian decline in Sri Lanka are of anthropogenic origins; habitat destruction and fragmentation, alien invasive species, wildlife diseases/pathogens, climate change and environmental pollution. Only 750 km2 of Sri Lanka are covered with tropical rainforests and this area is broken into 100 km2 fragments or less. It is difficult for amphibians to tolerate disturbances and to maintain a sustainable population size under these conditions. Alien and domestic species impose threats by direct predation, competition, disease contraction and habitat alteration. Parasites and pathogens, especially the chirtrid fungus, hamper the growth, reproductive success, and physical fitness of amphibians and can result in mortality. Climate change has reduced the distribution of amphibians by modifying vegetation and habitat structure rendering them unsuitable for some amphibians. Pollution, especially agro-chemicals, threaten amphibians causing anatomical malformations, physiological disorders and even mass mortalities. Furthermore, acid depositions causing diebacks in montane forests also destroy amphibian niches. This paper recommends a number of conservation initiatives including in-situ and ex-situ conservation, the establishment of buffer zones to protect core forests, promotion of research on biodiversity conservation, improvement of conservation policies and legal frameworks as well as community-based activities including raising public awareness, environmental education and the introduction of eco-friendly agricultural practices

Acidic deposition is comprised of sulfuric and nitric acids and ammonium derived from atmospheric emissions of sulfur dioxide, nitrogen oxides, and ammonia, respectively. Acidic deposition has altered soil through depletion of labile pools of nutrient cations (ie calcium, magnesium), ...

Acid Deposition or commonly known as Acid Rain is the term used to describe the factors that occurs when the acidic wastes in the air falls down on the ground. The two ways on how acid deposition occurs in the environment will also be discussed on this paper, the formation of acid rain, its causes and effect in the environment and the solutions that are addressed to greatly reduce the threat of acid rain.

We report biological changes at several UK Acid Waters Monitoring Network lakes and streams that are spatially consistent with the recovery of water chemistry induced by reductions in acid deposition. These include trends toward more acid-sensitive epilithic diatom and macroinvertebrate assemblages, an increasing proportional abundance of macroinvertebrate predators, an increasing occurrence of acid-sensitive aquatic macrophyte species, and the recent appearance of juvenile (<1 year old) brown trout in some of the more acidic flowing waters. Changes are often shown to be directly linked to annual variations in acidity. Although indicative of biological improvement in response to improving water chemistry, “recovery” in most cases is modest and very gradual. While specific ecological recovery endpoints are uncertain, it is likely that physical and biotic interactions are influencing the rate of recovery of certain groups of organisms at particular sites.

... Our analysis found that threshold conditions for potential forest impacts from Al stress are indicated by four successive measurement endpoints: (i) soil base saturation less than 15% of effective CEC; (ii) soil solution Ca/Al molar ratio ≤1.0 (for 50% risk); (iii) line root tissue Ca/Al ...

The MAGIC model was calibrated to 143 lakes in Sweden, all of which are monitored in Swedish national monitoring programmes conducted by the University of Agricultural Sciences (SLU). Soil characteristics of the lake catchments were obtained from the National Survey of Forest Soils and Vegetation also carried out by SLU. Deposition data were provided by the Swedish Meteorological and Hydrological Institute (SMHI). The model successfully simulated the observed lake and soil chemistry at 133 lakes and their catchments. The fact that 85% of the lakes calibrated successfully without being treated in an individual way suggests that data gathered by the national monitoring programmes are suitable for modelling of soil and surface water recovery from acidification. The lake and soil chemistry data were then projected into the future under the deposition scenario based on emission reductions agreed in the Gothenburg protocol. Deposition of sulphur (sea salt corrected) was estimated to decrease from 1990 to 2010 by 65–73%; deposition of nitrogen was estimated to decrease by 53%. The model simulated relatively rapid improvements in lake water chemistry in response to the decline in deposition from 1990 to 2010, but the improvements levelled off once deposition stabilised at the lower value. There was a major improvement of simulated lake water charge balance acid neutralising capacity (ANC) from 1990 to 2010 in all lakes. The modelled lakes were divided into acidification sensitive and non-sensitive. The modelled sensitive lakes are representative of 20% of the most sensitive lakes in Sweden. By 2010, the ANC in the sensitive lakes was 10 to 50 μeq L-1 below estimated pre-industrial levels and did not increase much further from 2010 to 2040. Soils at the majority of the modelled catchments continued to lose base cations even after the simulated decline in acid deposition was complete, i.e. after the year 2010. Based on this model prediction, the acidification of the Swedish soils will in general not be reversed by the deposition reduction experienced over the last 10 years and expected to occur by the year 2010.

Although the increased mobilization of aluminum from soils to surface waters is widely recognized as one of the most important ecological effects of acidic deposition, lumped-parameter mathematical models of acidification response typically overestimate the change in Al concentration under changing deposition by a considerable margin. The assumption of equilibrium with gibbsite (Al(OH)3) in the MAGIC model and other models of