Kristina matthews

Kristina Matthews Environmental Science — EVS 1001 2 4/23/13 Week 2 Individual Work There are human impacts that deal with four chemical cycles. The first cycle is to do with carbon. The second is to do with phosphorus. The third cycle is nitrogen. And the fourth cycle is sulfur. We will look at each one and how they impact humans and examples. Carbon effects human impact. “ Human intrusion into the carbon cycle is significant. As we will see shortly, we are diverting (or removing) 40 % of the photosynthetic productivity of land plants to support human enterprises” (p. 67). Carbon is in the atmosphere and is very complex on our earth. The carbon atoms are eaten by the animals and humans eat the animals. The phosphorus cycle is the soil minerals. “ The most serious human intrusion into the phosphorus cycle comes from the use of phosphorus — containing fertilizers” (p. 68). It is common on the soil and has the growth product in feeding our plants and animals and humans. It is very dangerous for our oceans as it makes the algae to overgrow and it kills the fish. Nitrogen is a unique cycle. Nitrogen is an element in the air. “ Human involvement in the nitrogen cycle is substantial. Many agricultural crops are legumes (peas, beans, soybeans, alfalfa), so they draw nitrogen from the air, thus increasing the rate of nitrogen fixation on land” (p. 70). Under this cycle there is nitrogen fixation which can becomes algae. Then there is the denitrification which “ is a microbial process that occurs in soils and sediments depleted of oxygen” (p. 69). The fourth and final cycle is sulfur. “ The largest human impact of the sulfur cycle is the additions of sulfur oxides to the atmosphere and the addition of sulfates to water” (p. 70). Finally, “ the four cycles we have looked at in depth differ in some important way” (p. 71). We have made everything speed up in the world. That minds that we need to watch what we are doing to the earth. Works Cited Richard T. Wright, D. F. (2014). Environmental Science. In D. F. Richard T. Wright, Environmental Science Toward a Sustianable Future (pp. 50 – 74). New Jersey: Pearson.