So, quite obviously, we’ve been studying the atmosphere in the 7th grade. We’ve learned about the layers and composition of the atmosphere, pressure and temperature changes throughout the atmosphere, and methods of heating in the atmosphere (convection, conduction, radiation). Most importantly, we’ve spent time discussing the value of the atmosphere: it provides a blanket of stable gases which allow us to breath, provides us with moisture, shields us from harmful radiation from the sun, and protects us from severe shifts in temperature.
Unfortunately (at times) for us humans, changes can be caused to the atmosphere, and the general conditions of the world as a consequence, by pollution.
Air pollution is: the contamination of the atmosphere by the introduction of foreign substances by human and natural sources.
There are two main types of air pollution:
- Primary Pollutants
- Secondary Pollutants
Primary Pollutants
These are pollutants that are directly put into the air by human or natural sources.
They can include gases like carbon dioxide and carbon monoxide, dust, sea salt, smoke from forest fires, volcanic ash and gas, and chemicals from human activity.
Secondary Pollutants
Secondary Pollutants occur when primary pollutants react with atmospheric gases to make new, hazardous substances.
For example – when the car exhaust produced by vehicles reacts with sunlight in the atmosphere, it produces smog, which can be hazardous to breath, etc.
Effects of Pollution
There are myriad effects of air pollution.
Just a few of them are:
Acid Precipitation
Air Pollution can mix with water in the air to create acid rain.
Acid rain can damage plants, animals and ecosystems around the world.
Damage to the Ozone Layer
As air pollutants (such as CFCs) are added to the atmosphere, they may damage the ozone layer. As the ozone layer is damaged, and begins to be perforated, it can let in excess UV radiation, which itself can be damaging to life on earth.
We will discuss the effects of air pollution on human health, and global climate change in future classes.
The article below is taken from Discovery.com
Toxic Gases Caused World’s Worst Extinction
Michael Reilly, Discovery News
Feb. 4, 2009 — An ancient killer is hiding in the remote forests of Siberia. Walled off from western eyes during the Soviet era and forgotten among the endless expanse of wilderness, scientists are starting to uncover the remnants of a supervolcano that rained Hell on Earth 250 million years ago and killed 90 percent of all life.
Researchers have known about the volcano — the Siberian Traps, for years. And they’ve speculated that the volcanic rocks, which cover an area about the size of Alaska, played a role in runaway global warming that led to the end — Permian mass extinction, the worst dying the planet has ever seen.
Now a team of researchers led by Henrik Svenson of the University of Oslo in Norway have performed a series of experiments, showing the volcano employed an arsenal of deadly weapons during its 200,000-year-long assault on the biosphere.
Prime among them was carbon. Searing magmas from the volcano intruded into the Tunguska Basin in eastern Siberia, a region laden with thick deposits of coal, oil and gas. Heat from the molten rock baked the hydrocarbons, turning the area into the world’s largest fossil fuel-burning plant. In all, the volcano may have belched as much as 100,000 gigatons of carbon into the air (all of humanity emits about eight gigatons of carbon annually).
That’s more than enough to cause a global climate apocalypse. But the team also wanted to know what happened when lava infiltrated the area’s abundant salt deposits. When heated in a laboratory to 275 degrees Centigrade (527 degrees Fahrenheit), the salts released a host of toxic gases, chief among them methyl chloride, an efficient ozone-killer.
“This is the first geologically realistic evidence that ozone collapse during the end-Permian could have actually happened,” Svenson said.
But there is still a lot of uncertainty surrounding the findings, Linda Elkins-Tanton of the Massachusetts Institute of Technology said.
“There is evidence of a large number of genetic mutations in the fossil record around this time,” she said, which could be the result of an onslaught of ultraviolet radiation due to a weak ozone layer. “But the idea of ozone destroyers is pretty new. The question is whether or not the eruptions were powerful enough to inject gases into the stratosphere.”
The answer may come from close examination of hundreds of pipe-like structures strewn throughout the Tunguska Basin. Often 300 meters (984 feet) in diameter, Svenson’s team believes the pipes are ancient volcanic craters left over after the lethal mix of carbon and chlorine gases exploded into the atmosphere.
The article below is taken from The LA Times
Mt. Redoubt volcano’s ‘unrest’ recalls 1989 eruption
Pete Thomas, LA Times
February 3, 2009 — The latest from the Alaska Volcano Observatory on the status of Mt. Redoubt: “Unrest at Redoubt Volcano continues. Seismic activity remains elevated above background.”
Sounds like a broken record, but at least Mt. Redoubt is providing ample warning and has all of Alaska on alert.
Longtime residents surely recall a five-month stretch that began in late 1989 during which the 10,197-foot volcano provided a string of eruptions and a steady outpouring of smoke and ash.
A United Press International article that Dec. 15 featured this initial announcement: “Redoubt Volcano southwest of Anchorage shook with thousands of small earthquakes Thursday, then erupted and shot a cloud of ash seven miles high.”
Farther down in the story: “The eruption followed 24 hours of constant warning tremors, which calmed down after the eruption ended, then picked up again…. The ash plume — which shot 35,000 feet above the two-mile-high mountain — was carried toward Anchorage by strong winds… But the ash cloud skirted Anchorage and dusted towns beyond the city.”
A day after a second, more violent eruption occurred that Dec. 17, the Associated Press reported: “Haze from the volcano drifted over Anchorage, Alaska’s largest city with more than 200,000 people. The debris caused power outages, disrupted air travel and triggered public-health warnings.”
But it was Christmas week and the economy was not in shambles. Shoppers, according to the report, filled “the streets and malls over the weekend.”
