Acid Rain Effects on Plants
Acid rain is rain or any other form of precipitation that is unusually acidic. It has harmful effects on plants, aquatic animals, and infrastructure. Acid rain is mostly caused by human emissions of sulfur and nitrogen compounds which react in the atmosphere to produce acids. In recent years, many governments have introduced laws to reduce these emissions.
Soil biology and chemistry can be seriously damaged by acid rain. Some microbes are unable to tolerate changes to 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, e.g. aluminium, and leach away essential nutrients and minerals.
Soil chemistry can be dramatically changed when base cations, such as calcium and magnesium, are leached by acid rain thereby affecting sensitive species, such as sugar maple (Acer saccharum).
Adverse effects may be indirectly related to acid rain, like the acid's effects on soil or high concentration of gaseous precursors to acid rain. High altitude forests are especially vulnerable as they are often surrounded by clouds and fog which are more acidic than rain.
Other plants can also be damaged by acid rain but the effect on food crops is minimized by the application of lime and fertilizers to replace lost nutrients. In cultivated areas, limestone may also be added to increase the ability of the soil to keep the pH stable, but this tactic is largely unusable in the case of wilderness lands. When calcium is leached from the needles of red spruce, these trees become less cold tolerant and exhibit winter injury and even death.
Wheatgrass Cultivation and Background Information
Wheatgrass refers to the young grass of the common wheat plant, Triticum aestivum, that is freshly juiced or dried into powder for animal and human consumption. Both provide chlorophyll, amino acids, minerals, vitamins, and enzymes. Claims about wheatgrass's health benefits range from providing supplemental nutrition to having unique curative properties. Some consumers grow and juice wheatgrass in their homes. It is often available in juice bars alone, or in mixed fruit and/or vegetable drinks. It is also available in many health food stores as fresh produce, tablets, frozen juice and powder.
The consumption of wheatgrass in the Western world began in the 1930s as a result of experiments by Charles F. Schnabel and his attempts to popularize the plant.
Schnabel, an agricultural chemist, conducted his first experiments with young grasses in 1930, when he used fresh cut grass in an attempt to nurse dying hens back to health. The hens not only recovered, but they produced eggs at a higher rate than healthy hens. Encouraged by his results, he began drying and powdering grass for his family and neighbors to supplement their diets. The following year, Schnabel reproduced his experiment and achieved the same results. Hens consuming rations supplemented with grass doubled their egg production. Schnabel started promoting his discovery to feed mills, chemist and the food industry. Two large corporations, Quaker Oats and American Dairies Inc., invested millions of dollars in further research, development and production of products for animals and humans. By 1940, cans of Schnabel's powdered grass were on sale in major drug stores throughout the United States and Canada.
Schnabel's research was conducted with wheatgrass grown outdoors in Kansas. His wheatgrass required 200 days of slow growth, through the winter and early spring, when it was harvested at the jointing or reproductive stage. It was at this stage that the plant reached its peak nutritional potential; after jointing, concentrations of chlorophyll, protein, and vitamin decline sharply. Harvested grass was dehydrated and made into powders and tablets for human and animal consumption. Wheatgrass grown indoors in trays for ten days contains similar nutritional content. Wheatgrass grown outdoors is harvested, dehydrated at a low temperature and sold in tablet and powdered forms. Wheat grass juice powder (fresh squeezed with the water removed) is also available either spray-dried or freeze-dried.
Proponents of wheatgrass claim regular ingestion of the plant can
- improve the digestive system
- prevent diabetes and heart disease
- cure constipation
- detoxify heavy metals from the bloodstream
- help make menopause more manageable
- promote general well-being.
While none of these claims have been substantiated in the scientific literature, there is limited evidence in support of some of these claims.
Source: Wikipedia (All text is available under the terms of the GNU Free Documentation License)
For More Information (Background, pictures and references):
Acid Rain: K-12 Experiments & Background Information