Environmental policy of the United States Environmental Protection Agency, were people with a history of opposition to the agency they were named to head. Since the environmental movement of the 1970s, the nature of environmental issues has changed. While the initial emphasis was on conventional air and water pollutants, which were the most obvious and easily measurable problems, newer issues are long-term problems that are not easily discernible and can be surrounded by controversy. Acid deposition, in the form of acid rain and dry deposition, is the result of sulfur and nitrogen dioxide being emitted into the air, traveling and landing in a different place, and
Lichens and nitrogen cycling and decrease the growth of the lichen. If the lichen cannot increase its photobiont growth, high nitrogen uptake may result in a higher concentration than it physiologically requires which will negatively affect the lichen and it's host plant as the other nutrients are too limiting. Lichen’s response to nutrient enrichment is both species-specific and dependent its environmental factors e.g. nutrient concentration, light availability and water supply. Lichen is nitrogen sensitive and change in nitrogen availability can affect its health greatly. Two main nitrogen stress factors for lichens are nitrogen deficiency and high nitrogen deposition. Both types of nitrogen stress result