Sulfuric acid anthropogenic

The production of acid rain starts when atmospheric sulfur dioxide is oxidized to sulfur trioxide in a complex series of reactions. SO3 is, in turn, hydrolyzed to sulfuric acid. Anthropogenic sources of sulfur dioxide include the burning of coal, the refining and burning of oil, and the smelting of copper ores. Until control measures started to come on line, the pH of rainwater in the northeastern United States and other areas downwind of such sources had fallen to values between 3 and 4. The best control measures have proven to be wet and dry scrubbers. As a result of installation of these flue-gas desulfurization (FGD) devices, the amount of sulfur and nitrogen oxides released to the atmosphere has measurably decreased in the last several decades. 

DMS is photochemically oxidized in the atmosphere to methanesulfonic and sulfuric acids. These strong acids contribute, along with nitric and organic acids, to the natural acidity of precipitation. Recent problems with acid rain have aroused interest in the anthropogenic and natural sources of volatile sulfur compounds (2). 

Before assessing how a chemical moves in the environment, the relevant media, or compartments, must be defined. The environment can be considered to be composed of four broad compartments—air, water, soil, and biota (including plants and animals)—as shown in Fig. 6.6. Various approaches to modeling the environment have been described.14-16 The primary difference in these approaches is the level of spatial and component detail included in each of the compartments. For example, the most simplistic model considers air as a lumped compartment. A more advanced model considers air as composed of air and aerosols, composed of species such as sodium chloride, nitric and sulfuric acids, soil, and particles released anthropogenically.17 A yet more complex model considers air as composed of air in stratified layers, with different temperatures and accessibility to the earth s surface, and aerosols segmented into different size classes.16 As the model complexity increases, its resolution and the data demands also increase. Andren et al.16 report that the simplest of models with lumped air, water, and soil compartments is suitable for... 

In the last 150 years the anthropogenic emission of sulfur has increased dramatically, primarily due to combustion processes [1]. In the 1950s anthropogenic emission surpassed natural emission and the atmospheric sulfur cycle is one of the most perturbed biogeochemical cycles [1,2]. The oceans are the largest natural source of atmospheric sulfur emissions, where sulfur is emitted in a reduced form, predominantly as dimethyl sulfide (DMS) and to a much lesser extent carbonyl sulfide (OCS) and carbon disulfide (CS2) [3]. Ocean emitted DMS and CS2 are initially oxidised to OCS, which diffuses through the troposphere into the stratosphere where further oxidation to sulfur dioxide (SO2), sulfur trioxide (SO3) and finally sulfuric acid (H2SO4) occurs [1-4]. 

Large quantities of sulfur dioxide enter the atmosphere each year from anthropogenic sources, mainly the combustion of fossil fuels and the smelting of metals. S02 indisputably ranks as a prominent pollutant, and it is understandable that research of the past 30 yr dealing with atmospheric sulfur has concentrated on such problems as the dispersal of S02 from power stations and urban centers, its conversion to sulfuric acid, the formation of sulfate aerosols, and the deposition of sulfate and S02 at the ground surface. 

The major anthropogenic sources of sulfur dioxide emissions are fossil fuel and biomass burning, iron and non-ferrous metal smelting and sulfur acid production. The natural emissions from volcano eruptions and massive forest fires should be also taken into account if any occur in the considered period. 

Natural source Al contribution greatly exceeds the 13% contribution from anthropogenic sources (Syracuse 1999), with most Al released into the atmosphere. Al in natural waters is mainly derived from weathering of rocks and minerals. Al and sulfuric acid are released from inactive mines and mine tailings due to weathering of sulfide ores. The species of Al in the environment is usually unknown. 

The spread and intensification of precipitation acidity through northern Europe is a well described phenomenon(1). The temporal increase of acidity is attributed to increased anthropogenic emissions of NO and 802(2). While sulfuric acid is considered to be the major acid(2), the net acidity is controlled by the interaction of sulfuric and nitric acids with basic ammonia and soil dust(3). 

Both heterogeneous and homogeneous nucleation appear to play roles in ice formation in the upper troposphere. Liquid droplets several microns in radius can be found at temperatures down to about T —35°C [38] (Fig. 2). These are probably concentrated solutions of sulfuric acid, ammonium sulphate, and possibly other nitrogen compounds formed on deliquescent aerosols. Some of the aerosols on which the ice particles nucleate are formed aloft by gas-to-particle conversion in the clear air surrounding clouds ([39]) some originate from volcanos, and some arise from gas and/or particle anthropogenic sources. 

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