Archive for 'LexyL'
First, we talked about smog. Term coined by combining smoke + fog to get smog. Here are the two types we learned:
- Sulfur-based Smog: “industrial smog”
- Nitrogen-based Smog: “photochemical smog”
Sulfur-based Smog takes on a gray color. When coal is burned compounds within the coal interact with atmospheric oxygen which then causes iron oxide and sulfur dioxide to be released in the atmosphere. *Sulfur oxides are primary air pollutants. The sulfur dioxide in the air can oxidize, then dissolve into atmospheric water droplets to form sulfuric acid. Sulfuric acid is a secondary air pollutant and a main component of acid rain. Acid rain contributes to deforestation and the corrosion of buildings, statues and paint.
Nitrogen-based Smog takes on a brown color. The combustion of an engine leads to the release of many different chemicals. One compound in particular is NO2. When ultra-violet rays from the sun hit NO2, that is now in the atmosphere because of vehicle emissions, an Oxygen atom breaks away but quickly combines with O2 to form O3 also known as ozone. Ozone is good and bad, it just depends on where it is in the atmosphere. Ozone belongs in the stratosphere where it can protect us from the sun’s harsh rays. When ozone is down in the lithosphere it is considered a pollutant because it traps heat and contributes to thermal inversion.
This diagram basically explains that the combustion of an engine leads to emissions of both regulated and unregulated pollutants. (Click to enlarge image) CO, hydrocarbons, NO, NO2 and particulate matter are all regulated. CO2, H2O and N2 are unregulated. The result of these emissions produce primary and secondary pollutants. Secondary pollutants include: ozone formation, acid rain and photochemical smog.
Posted: April 13th, 2011 under LexyL, Scribe Post, Unit 13-Air Pollution & Climate Change.
Tags: air pollution, atmosphere, carbon, coal, fossil fuels, nitrogen, oil, ozone, warming gases
In class on Monday we talked about Speciation, or the creation of new species. What helps drive the process of speciation is natural selection. We learned 4 different aspects of natural selection:
- Genetic Variation (mutation)
- Over Production of Offspring
- Struggle for Existence (food limitation)
- Differential Survival & Reproduction (heredity)
A source of genetic variation is mutation, which is considered “the fuel” for evolution. Remember… populations evolve, not individuals. As species reproduce each generation of offspring is different because the parents’ genes mix and the result can be a variety of things. Mutation is random, the behavior, shape or appearance that an organism inherits will not necessarily always be beneficial, although natural selection favors organisms that possess features that give them an advantage in survival. Thus organisms possessing unfavorable traits will die off and their trait will die with them (decreasing their presence within a population).
The 3 types of Natural Selection we learned about are:
- Stabilizing: when the “average” individuals in the population are favored of the extremes of a trait
- Disruptive: when individuals at both of the extremes of a trait are favored over the average individuals
- Directional: when individuals possessing an extreme trait at one end of the curve are favored
*Disruptive Selection plays an important role in speciation because as variance within the population increases, dividing the population into 2 distinct groups, speciation becomes possible.
Lastly, we covered 2 types of Speciation:
- Allopatric: speciation by geographic isolation. This type of speciation is much like a cheesy movie where the main character goes off having adventures that changes him so drastically that when he returns nobody in his hometown recognizes him. Organisms that were once part of the same population (same specie) and were separated geographical underwent mutation creating new traits only shared in that isolated population, eventually resulting in a new specie.
- Sympatric: speciation in which new species evolve from a single ancestral species while inhibiting the SAME GEOGRAPHICAL REGION. For example, there is small volcanic crater lake in Nicaragua that is completely isolated, so there is no physical way it could be connected to any other body of water. A study was done on the lake and this is what was concluded, “We find, first, that crater Lake Apoyo was seeded only once by the ancestral high-bodied benthic species Amphilophus citrinellus, the most common cichlid species in the area; second, that a new elongated limnetic species (Amphilophus zaliosus) evolved in Lake Apoyo from the ancestral species (A. citrinellus) within less than ~10,000 yr; third, that the two species in Lake Apoyo are reproductively isolated; and fourth, that the two species are eco-morphologically distinct.” (http://www.nature.com/nature/journal/v439/n7077/full/nature04325.html)
*From Mr. W, the brief video example of allopatric speciation shown in class:
Personally I think that the world’s biggest problem is not having enough materials to support the global population and our lack of understanding that the materials will run out. For example, oil is a nonrenewable resource but we continue to rely on it. We need to either find a substitute material to replace oil or create new vehicles and machines that depend on a different source of energy.