Threats to Biodiversity Habitat Loss Habitat Fragmentation –Biotic Issues –Abiotic Issues Habitat Degradation –Air Pollution –Water Pollution –Land Pollution
Exotic Species Non-native organisms that move-in to a particular area There can be a lack of competitors = exponential growth Can take over the niches of native species Example: Page 124
Conservation Sustainable use: –Use what you need, but dont damage the ecosystem Is this a good example of sustainable use?
Humans & The Environment Pest Control –Benefits vs. Problems –EX: DDT
Humans & The Environment Ozone (O 3 ) Depletion –O 3 forms a good layer around the Earth –CFC release is breaking down the protective ozone layer –UV rays increase skin cancers & other cell mutations to plants & animals!
How is Acidity Measured? When we observe acid rain, acidity is measured in units called pH. The pH scale is from 0 to 14 –pH 7 indicates neutral –higher pH numbers = alkalinity (base) –smaller numbers = acid Well do more on pH in the Biochemistry chapter
Natural Acid Precipitation CO 2 combines with water to form a weak acid H 2 CO 3 (carbonic acid) But we are adding to the problem… –by adding nitric and sulfuric acids Look at the clean rain – its already slightly acidic???
Effects of Acid Precipitation In Japan, rain which registers pH 5.6 or less is considered acid rain; some 80- 90% of the rain that falls in Japan in a year is acid rain. In Japan, acid rain with acidity equal to lemon juice has been observed at Mount Tsukuba in 1984 (pH 2.5) and at Kagoshima in 1987 (pH 2.45). The problem is even more serious in N. America and Europe. –In those regions, forests are withering and lakes becoming uninhabitable to fish, and stone structures such as buildings and bronze statues are being damaged by corrosion. 19701985
Humans & The Environment Global Warming –The Greenhouse Effect –Fossil fuels give off lots of CO 2 –This builds a blanket around the earth –It is predicted that the Earth temp. will increase ~5 0 C before 2050 = Ice age????
Carbon Dioxide Increase Carbon dioxide levels fluctuate seasonally The average level is steadily increasing Burning of fossil fuels & deforestation are contributing to the increase
Greenhouse Effect Greenhouse gases impede the escape of heat from Earths surface