Mise au point et réalisation d' une méthode de dosage du rapport N-15/N-14 dans les nitrates des glaces polaires: Fev. 1989 - Sept. 1989

• Main Author: Bordat, P.
• Format: Report
• Language: French
• Published: Kernforschungsanlage Jülich, Verlag 1989
• Subjects: Carbonic acid
• Online Access: https://juser.fz-juelich.de/record/845987; https://juser.fz-juelich.de/search?p=id:%22FZJ-2018-03159%22

Before the industrial period, the phenomenon of pollution was already linked to human activity. Since the beginning of industrialisation, fog, smoke and gases have been identified in the big industrial cities in Western Europe and North America. The phenomenon called "Acid Rain" had already described by the year 1852 inManchester, but scientific studies of it began actually after the Second World War. Public opinion was then on alert. A great number of ecological disasters since that time have surely played a big role in the emergence of ecological political parties. The governments of industrial countries have devoted budgets for environmental research. The first step, naturally, was the comprehension of the phenomenon. However, the determination of the atmospheric cycles of these different pollutants is yet not complete. Particulary, the understanding of the evolution of these different cycles as a function of time is still developing. In tempered countries, the study of atmospheric acidity is playing a great role today in relation with that phenomenon. It is now well known that this acidity is essentially due to nitric and sulfuric acids.Acid precipitation is a mixture of strong mineral acids - sulfuric, nitric and in somelocations hydrochloric acid- and it is found in both rain and snow. The pH (acidity)of distilled water in equilibrium with atmospheric carbon dioxide is approximately 5.6. Acid precipitation is defined for precipitations having a pH under this value. We must recognize that acids are also deposited from the air by processes of dry deposition. There may also be weak organic acids and carbonic acid present in rain and snow, but they are seldom important sources of protons when the pH is below 5.0. This is why, in a strict definition, acid precipitation refers only to the presence of nitrogen oxides and SO$_{2}$/SO$_{3}$, which have dissolved in cloud and rain to form respectively nitric and sulfuric acids (fig. 1). [.]