LIFESCI 1 Lecture Notes - Lecture 29: Nitrogen Cycle, Habitat Destruction, Ecological Pyramid
Document Summary
1-2% of fossil fuel consumption = makes n-fertilizer. Eutrophication = nutrients from runoff increase in pop of algae & cyanobacteria: algae/cyanobacteria pops = sink to bottom heterotrophic bacteria feed on them, high rates of bacteria respiration = deplete o2 in bottom waters. Po4(3-) = used as fertilizer & runoff = eutrophication. Everglades = low phosphate levels originally, but no 100x phosphate levels: comes from phosphate fertilizer runoff phosphate loving plants expand at expense of native plants = decrease diversity. No industrial process to produce phosphate = non-renewable eventually run out: only a few places in world have sediments w/ high phosphate to mine = depleted. 2 options to meet food needs of more people: devote more land to crops, increase yield of crops already in place. Costs = increasing crop area = need to burn down forests & grasslands: decreases biological store of carbon = threatens diversity, increasing yield = need more fertilizers & fossil fuels to power farm machinery.
