User:NHSavage/sandbox
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Old stuff I deleted - try and verify all of this.
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[edit] Adverse effects
Decades of enhanced acid input has increased the environmental stress on high elevation forests and aquatic organisms in sensitive ecosystems.[citation needed] In extreme cases, it has altered entire biological communities and eliminated some fish species from certain lakes and streams.[citation needed] In many other cases, the changes have been more subtle, leading to a reduction in the diversity of organisms in an ecosystem. This is particularly true in the northeastern United States and Canada, where the rain tends to be most acidic, and often the soil has less capacity to neutralize the acidity. The adverse effect acid rain has on forests has decimated Canada's and Germany's national forests.
Acid rain also can damage certain building materials and historical monuments.
Some scientists have suggested links to human health, but none have been proven.[1]
[edit] Effects on lake ecology
There is a strong relationship between lower pH values and the loss of populations of fish in lakes.[citation needed] Below 4.5 virtually no fish survive, whereas levels of 6 or higher promote healthy populations. Acid in water inhibits the production of enzymes which enable fish's larvae to escape their eggs. It also mobilizes toxic metals such as aluminium in lakes. Aluminium causes some fish to produce an excess of mucus around their gills, preventing proper ventilation. Phytoplankton growth is inhibited by high acid levels, and animals which feed on it suffer.
Many lakes are subject to natural acid runoff from acid soils, and this can be triggered by particular rainfall patterns that concentrate the acid. An acid lake with newly-dead fish is not necessarily evidence of severe air-pollution.
[edit] Effects of acid rain on soil chemistry
The effect of acid rain on soil chemistry is consistent with the soil forming process, podzolisation. Podzolisation is a complex process (or number of sub-processes) in which organic material and soluble minerals (commonly iron and aluminium) are leached from the A to the B horizon. In nature, podsols form under moist, cool, and acidic conditions.
[edit] Effects of acid rain on soil biology
Soil biology can be seriously damaged by acid rain. Some tropical microbes can quickly consume acids[2] but other types of microbe are unable to tolerate low pHs and are killed. The enzymes of these microbes are denatured (changed in shape so they no longer function) by the acid.
The hydronium ions of acid rain also mobilize toxins and leach away essential nutrients.
Forest soils tend to be inhabited by fungi, but acid rain shifts forest soils to be more bacterially dominated. In order to fix nitrogen many trees rely on fungi in a symbiotic relationship with their roots. If acidity inhibits the growth of these mycorrhizae associations this could lead to trees struggling to fix nitrogen without their symbiotic partners.
[edit] Other adverse effects
Trees are harmed by acid rain in a variety of ways. The waxy surface of leaves is broken down and nutrients are lost, making trees more susceptible to frost, fungi, and insects. Root growth slows and as a result fewer nutrients are taken up. Toxic ions are mobilized in the soil, and valuable minerals are leached away or (as in the case of phosphate) become bound to aluminium or iron compounds, or to clay.
The toxic ions released due to acid rain form the greatest threat to humans. Mobilized copper has been implicated in outbreaks of diarrhea/diarrhoea [citation needed] in young children and it is thought that water supplies contaminated with aluminium cause Alzheimer's disease.
Acid rain can cause erosion on ancient and valuable statues and has caused considerable damage. This is because the sulfuric acid in the rain chemically reacts with the calcium in the stones (lime stone, sandstone, marble and granite) to create gypsum, which then flakes off. This is also commonly seen on old gravestones where the acid rain can cause the inscription to become completely illegible.
Acid rain also causes an increased rate of oxidation for iron.
