『Abstract
In this review article, anthropogenic activities that cause acidification
of Earth's air, waters, and soils are examined. Although there
are many mechanisms of acidification, the focus is on the major
ones, including emissions from combustion of fossil fuels and
smelting of ores, mining of coal and metal ores, and application
of nitrogen fertilizer to soils, by elucidating the underlying
biogeochemical reactions as well as assessing the magnitude of
the effects. These widespread activities have resulted in (1)
increased CO2 concentration in the atmosphere
that acidifies the oceans; (2) acidic atmospheric deposition that
acidifies soils and bodies of freshwater; (3) acid mine drainage
that acidifies bodies of freshwater and groundwaters; and (4)
nitrification that acidifies soils. Although natural geochemical
reactions of mineral weathering and ion exchange work to buffer
acidification, the slow reaction rates or the limited abundance
of reactant phases are overwhelmed by the onslaught of anthropogenic
acid loading. Relatively recent modifications of resource extraction
and usage in some regions of the world have begun to ameliorate
local acidification, but expanding use of resources in other regions
is causing environmental acidification in previously unnoticed
places. World maps of coal consumption, Cu mining and smelting,
and N fertilizer application are presented to demonstrate the
complex spatial heterogeneity of resource consumption as well
as the overlap in acidifying potential derived from distinctly
different phenomena. Projected population increase by country
over the next four decades indicates areas with the highest potential
for acidification, so enabling anticipation and planning to offset
or mitigate the deleterious environmental effects associated with
these global shifts in the consumption of energy, mineral, and
food resources.』
Contents
1. Introduction
1.1. Acidifying reactions
2. Acidification of the atmosphere
2.1. Emissions of S and N compounds and acidic atmospheric
deposition
2.1.1. Decreasing emissions in the Western hemisphere
2.1.2. Increasing emissions in developing countries
2.2. Other emissions to the atmosphere
3. Elevated atmospheric CO2 and ocean acidification
3.1. Neutralizing reactions important in the oceans
4. Acidification of freshwaters
4.1. Acid mine drainage
4.1.1. Metal ores
4.1.2. Coal
4.2. Acidic atmospheric deposition
4.3. Neutralizing reactions important in freshwaters
5. Acidification of soils
5.1. Fertilizer use for crop production
5.2. Neutralizing reactions important in soils
6. Global aggregate effect
Acknowledgments
References