Does the Amazon Rainforest Really Produce 20 Percent of the World's Oxygen?

SL_Photography/iStock via Getty Images
SL_Photography/iStock via Getty Images

Richard Muller:

No. In fact, under normal conditions (prior to human-caused fires) the Amazon [rain]forest is in a steady state. Oxygen is produced by photosynthesis and consumed by decay. If these were out of balance, then the mass of wood in the Amazon must change.

That means if the Amazon were to disappear today, instantly (e.g. we harvested all the wood and used it to build houses) then the oxygen and carbon dioxide in the atmosphere would continue on at the same level. Until, that is, the wood rots. Then the carbon dioxide levels would increase.

Except for the biomass decrease from human-caused fires, the biomass of the Amazon has not been changing. That means that no net carbon dioxide is being removed from the atmosphere, so no net oxygen is being released from carbon dioxide.

Recently the Amazon biomass has been changing due to fires. When that happens, the wood and other carbohydrates in the trees combine with oxygen and produce CO2 and H2O. Thus the burning of the rainforests contributes to global warming.

But under normal situations, when the biomass of the Amazon is not changing, there is no net production of oxygen or carbon dioxide.

Incidentally, many writers who don’t understand this—and mistakenly think that the Amazon produces net oxygen—double their error by using a backward metaphor. They refer to the Amazon basin the "lungs of the world," but lungs are the organ that remove oxygen from the air and replace it with carbon dioxide, not the other way around.

Where did the 20 percent figure come from? The best guess is that ecologists have calculated that 20 percent of the photosynthesis of the world takes place in the Amazon basin. But so does 20 percent of the consumption.

This post originally appeared on Quora. Click here to view.

Has An Element Ever Been Removed From the Periodic Table?

lucadp/iStock via Getty Images
lucadp/iStock via Getty Images

Barry Gehm:

Yes, didymium, or Di. It was discovered by Carl Mosander in 1841, and he named it didymium from the Greek word didymos, meaning twin, because it was almost identical to lanthanum in its properties. In 1879, a French chemist showed that Mosander’s didymium contained samarium as well as an unknown element. In 1885, Carl von Weisbach showed that the unknown element was actually two elements, which he isolated and named praseodidymium and neodidymium (although the di syllable was soon dropped). Ironically, the twin turned out to be twins.

The term didymium filter is still used to refer to welding glasses colored with a mixture of neodymium and praseodymium oxides.

One might cite as other examples various claims to have created/discovered synthetic elements. Probably the best example of this would be masurium (element 43), which a team of German chemists claimed to have discovered in columbium (now known as niobium) ore in 1925. The claim was controversial and other workers could not replicate it, but some literature from the period does list it among the elements.

In 1936, Emilio Segrè and Carlo Perrier isolated element 43 from molybdenum foil that had been used in a cyclotron; they named it technetium. Even the longest-lived isotopes of technetium have a short half-life by geological standards (millions of years) and it has only ever been found naturally in minute traces as a product of spontaneous uranium fission. For this reason, the original claim of discovery (as masurium) is almost universally regarded as erroneous.

As far as I know, in none of these cases with synthetic elements has anyone actually produced a quantity of the element that one could see and weigh that later turned out not to be an element, in contrast to the case with didymium. (In the case of masurium, for instance, the only evidence of its existence was a faint x-ray signal at a specific wavelength.)

This post originally appeared on Quora. Click here to view.

Can You Ever Truly Lose Your Accent?

DGLimages, iStock via Getty Images
DGLimages, iStock via Getty Images

You may be able to pull off a Spanish accent when showing off your Antonio Banderas impression, but truly losing your native accent and replacing it with a new one is a lot harder to do. The way you speak now will likely stick with you for life.

According to Smithsonian, our accent develops as early as 6 months old—accents being the pronunciation conventions of a language shaped by factors like region, culture, and class. When a baby is learning the words for nap and dad and play, they're also learning how to pronounce the sounds in those words from the people around them. Newborn brains are wired to recognize and learn languages just from being exposed to them. By the time babies start talking, they know the "right" pronunciations to use for their native language or languages.

As you get older, your innate understanding of foreign accents and languages gets weaker. If you're an English speaker raised in Boston, you may think that the way someone from Dallas speaks English sounds "wrong" without being able to articulate what it is that makes them sound different. This is why pulling off a convincing foreign accent can be so difficult, even if you've heard it many times before.

Around age 18, your ability to learn a second language takes a steep nosedive. The same may be true with your ability to speak in a new accent. If you immerse yourself in a foreign environment for long enough, you may pick up some ticks of the local accent, but totally adopting a non-native accent without making a conscious effort to maintain it is unlikely as an adult.

There is one exception to this rule, and that's Foreign Accent Syndrome. Following a head injury or stroke, some people have reported suddenly speaking in accents they didn't grow up using. The syndrome is incredibly rare, with only 100 people around the world having been diagnosed with it, and medical experts aren't sure why brain injuries cause it. But while patients may be pronouncing their words differently, they aren't exactly using foreign accents in the way most people think of them; the culprit may be subtle changes to muscle movements in the jaw, tongue, lips, and larynx that change the way patients pronounce certain vowels.

[h/t Smithsonian]

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