Treesearch

The total annual emissions of sulfur oxides and nitrogen oxides in Canada are estimated to be 7.2 x 106 tons and 1.4 x 106 tons, respectively. These figures represent 5% and 2%, respectively, of the estimated worldwide anthropogenic emissions. Nearly two-thirds of the Canadian SO2 emissions come from primary smelters located in low population areas. The remainder originate from natural gas processing, pulp mills, fuel combustion and transportation in the more heavily populated areas. Transportation is the major source of oxides of nitrogen. No coordinated precipitation sampling has been...

The impact of acid precipitation reflects a usually deleterious balance between good and bad effects which may lead to serious and sometimes extreme degradation of aquatic as well as terrestrial ecosystems, particularly around metal smelters. Addition of hydrogen ions as sulfuric, nitric, and hydrochloric acid can alter and impoverish the species composition of biotic communities, and lead to severe leaching of beneficial metal cations such as calcium from ecosystems. Heavy metals and other trace elements which accompany acid precipitation may reach toxic levels, particularly where acid...

Extensive studies of precipitation chemistry during the last 20 years have clearly shown that highly polluted precipitation falls over large areas of Scandinavia, and that this pollution is increasing in severity and geographical extent. Precipitation in southern Norway, Sweden, and Finland contains large amounts of H+, SO4-2, and NO3-1 ions, along with heavy metals such as Cu, Zn, Cd, and Pb, that originate as air pollutants in the highly industrialized areas of Great Britain and central Europe and are transported over long distances to Scandinavia, where they are deposited in precipitatio...

There are several areas in Canada that could receive acidic fallout. Only in the area that produces Canada's largest single source of sulfur oxides has there been appreciable research. In the Sudbury region of Ontario, Canada, fallout of sulfur oxides has been shown to be responsible for damage to vegetation, lakes and fishes. The acidic fallout has been shown to effect a rate of acidification in many lakes that over several decades has resulted in the extinction of many species of fishes. Fishes exhibit profound differences in acid tolerance but show some similarities in their physiologica...

Current and historic geographic distributions of acidity in Adirondack lakes were examined in relation to regional edaphic, climatic, and physiographic features. Acid conditions are currently predominant in high elevation drainage lakes having small watershed/surface area ratios. Comparable levels of acidity were found only in small seepage lakes and bog ponds during the 1930's. Increased acidity in the high elevation lakes can be quantitatively related to the occurrence of excess acid forming anions of atmospheric origin. Knowledge of this stoichimetric relationship and the morpho-edaphic...

Rain experiments were run with various temperature differences between the warm rain and the cool receiving water. The rain intensities were uniform and the raindrop sizes were usually uniform (2.2 mm, 3.6 mm, and 5.5 mm diameter drops). Two drop size distributions were also used.

Recurrent biological investigations have been made in six lakes in two areas in western Sweden. It has been found that the supply of acid substances induces long-term biological perturbations at all trophic levels in the lake ecosystem. Among these changes, the sphagnum expansion is believed to strongly affect the dynamics in the lake. A quantification of the Sphagnum expansion in different depth zones of a lake was made. The rate of this invasion was found to be highest in shaded and sheltered areas of the littoral. The abundance of Sphagnum mats is furthermore negatively correlated to...

The pH and amount of rainfall from over 60 selected stations throughout northern and lower Michigan was determined from September 1972 to December 1974. Precipitation pH was determined for each station by calibrated electrode meters. The seasonal weighted average and median pH from all stations in the study was 5.0 and 6.3, respectively. Daily readings from stations throughout Michigan indicate that pH is dependent on the amount of rainfall and that variations in it are often locally controlled. Collectively the pH values suggest carbonic acid control for most of the state. Annual median...

The dense network of 12 rainguages, covering an area of 6 km in diameter, was reinstalled near PEPCO's 710 MW Chalk Point power plant in southern Maryland. The rainwater samples were collected from July to December 1974. This second season's collection of rainwater samples were analyzed and results showed a general shifting of pH toward higher values since the operation of a cooling tower. The pH values changed from a range of 3.4 to 4.6 to a range of 4.0 to 4.8. Graphs of mean pH distribution over our dense network show the influence of the cooling tower. Several selected cases of...

The rainwater pH was measured in a total of 22 storms which occurred in 1972 and 1974 in the METROMEX (METROpolitan Meteorological EXperiment) rainwater sampling network. The network consists of 81 collectors in an area of 1800 km² over and east of St. Louis, Missouri. The data set is composed of dry fallout samples as well as precipitation samples which have been analyzed independently. An analysis of the frequency distribution of these data show the rainfall samples form a bimodal distribution of pH with relative frequency maxima at pH 7.0 and 4.0 while the dry samples are unimodal with...