Framingham opposition grows to Sudbury River EPA project

THE STORY:

For sixty-one years, chemical companies in Ashland, MA dumped their chemical waste into the ground near the Sudbury River. Rain washed the chemicals, including the toxic chemical mercury,  into the river. The mercury was carried downstream and dangerous amounts of it still is found in the water and the riverbed. The federal Environmental Protection Agency has published a plan to help restore the river’s water quality, but some local residents want to stop the agency from carrying it out.

LINK:  http://www.metrowestdailynews.com/features/x511627121/Framingham-opposition-grows-to-Sudbury-River-EPA-project?photo=0

THE CHEMISTRY BEHIND THE NEWS:

Mercury is a chemical element which is represented by  the symbol Hg.  In its elemental form it is a metal. It is unusual as it is a liquid at room temperature. Because it is a liquid, mercury evaporates fairly easily to form mercury vapor, which has the chemical symbol Hg(g). Although both are harmful, mercury vapor is more toxic than the liquid metal because the vapor is absorbed easily through the lungs.  In the body, elemental mercury reacts with enzymes that contain the element selenium, deactivating them and leading to brain and nerve damage.

In the presence of oxygen or sulfur, mercury is oxidized to the mercury(II) ion, Hg²⁺. This ion is known to cause kidney damage.

Although these two forms of mercury are toxic, the mercury in the Sudbury river exists in an even more toxic form called methyl mercury. The chemical formula for methyl mercury is [HgCH₃]⁺.  Methyl is the chemical name for the CH₃ part of the molecule. Methyl mercury is formed from elemental mercury when it is buried in places with low oxygen and large amounts of decaying organic material, such as riverbeds and lake bottoms. Bacteria that live in these environments have enzymes that add the methyl group to the mercury atom.

In living organisms, methyl mercury binds tightly to the amino acid cysteine, which is found in proteins. That means that it is absorbed very easily when it is ingested. It also hangs around in the body for a long time. If a human being eats a fish contaminated with methyl mercury, half of the methyl mercury will still be in their body after 50 days. This means that methyl mercury can build up in the bodies of animals like fish and people that keep eating contaminated food over a long period of time.

The  EPA has determined that the amount of methyl mercury that is in the Sudbury River is dangerous to those people who eat fish they catch in the river. The methyl mercury may also be damaging the wildlife such as birds, fish, turtles, and mammals that live in the river. Therefore, they are proposing to place a layer of sand over the contaminated river bottom to keep the mercury from spreading into the water.

LINKS FOR MORE INFORMATION:

Information about mercury chemistry and toxicity

How dyes were manufactured at the chemical plants in Ashland MA

The EPA’s website for the Nyanza superfund site and the Sudbury River clean-up plan

 

 

U.N. climate change report points blame at humans

THE STORY:

Scientists are 95% confident that humans are affecting the Earth’s climate, according to the latest report from the UN International Panel on Climate Change.  Average air and ocean temperatures have measurably increased since 1950.

LINK:  U.N. climate change report points blame at humans

THE CHEMISTRY BEHIND THE NEWS:

Although the Earth’s climate is very complex, the scientists from the IPCC have concluded that the largest reason for climate change is that there has been a 40% increase in the amount of carbon dioxide in the atmosphere.

Most of the carbon dioxide in the atmosphere comes from humans using fossil fuels such as gasoline, oil, natural gas, and coal. These substances all contain carbon, and when they burn, the carbon combines with oxygen in the air to produce carbon dioxide. For example, anthracite coal is almost pure carbon. It burns according to the equation: C(s) + O2(g) –> CO2(g)

Carbon dioxide warms the atmosphere because it absorbs infrared light. Infrared light is light that has a slightly longer wavelength than visible light. We can’t see infrared light, but we can feel it as heat.

When sunlight hits the ground, the ground absorbs the visible light and its temperature rises. The ground then emits some of that energy as infrared light. If you have ever stood in a parking lot on a sunny day, you have felt the infrared light radiating from the asphalt. Usually, a lot of that infrared radiation (heat) would just go straight through the atmosphere into outer space, because the nitrogen and the oxygen in the air do not absorb infrared light very well.

But if there is carbon dioxide in the air, it absorbs the infrared light. The reason it absorbs the infrared light is because a photon of infrared light has just the right energy to change the vibrations in the carbon dioxide molecule. Once the carbon dioxide absorbs the light, its temperature increases, and it can pass that extra energy on to the other molecules around it. So the overall effect is that the heat from the sun is trapped by the carbon dioxide and the air gets hotter.

A similar effect happens in the greenhouses used to grow plants, because glass is also an excellent absorber (and emitter) of infrared light, so the IR light given off by the warm soil is absorbed by the glass and reflected back to keep the greenhouse warm. That is why carbon dioxide is called a greenhouse gas.

LINKS FOR MORE INFORMATION:

International Panel on Climate Change Report