XPRIZE Competition Poses Ocean Acidity Challenge
Sep20

XPRIZE Competition Poses Ocean Acidity Challenge

Today’s post is by Puneet Kollipara, intern at C&EN and an aquatic acidity aficionado. Humans pump carbon dioxide into the atmosphere by burning fossil fuels, but not all of it stays in the air. About one-fourth of the released carbon dioxide dissolves into the oceans, where it has been lowering the global average pH of seawater and thereby threatening aquatic ecosystems. Unfortunately, the ocean is as complex as it is spacious, and ocean pH doesn’t change uniformly across its depth. To get the full picture, scientists need a lot of data, but current techniques for monitoring ocean pH are generally expensive, aren’t always reliable, and can’t go very deep underwater. Right now, the U.S. National Oceanic and Atmospheric Administration (NOAA), for instance, has 18 ocean-chemistry monitors at various locations—more than anyone else in the world—but none of these sensors takes measurements below surface waters. “As you can imagine, that does not really represent the global oceans very well,” says Christopher L. Sabine, an oceanographer at NOAA’s Pacific Marine Environmental Laboratory. A 22-month competition launched by the XPRIZE Foundation, a nonprofit aiming to spur technological innovation for society’s betterment, seeks to change that. The newly announced $2 million Wendy Schmidt Ocean Health XPRIZE calls on innovators of all stripes, both professional and amateur, to design better pH-measurement technologies. “The idea with the XPRIZE is to develop robust, inexpensive sensors that can be deployed much more easily,” says Sabine, whose NOAA lab is partnering with XPRIZE for the competition. Half of the $2 million prize will be awarded for the development of an affordable, reliable sensor, Sabine says. The other half will go toward a system that can accurately profile pH changes, including at great depths; such an instrument might start deep in the ocean and take real-time measurements as it’s lifted to the surface. Two types of instruments are currently in mainstream use for measuring ocean pH, but both have significant drawbacks. The first type, potentiometric sensors, involves probing a water sample with a device containing two electrodes. One electrode is enveloped in a semipermeable membrane that lets ions pass through, and the other is exposed directly to the water as a reference. Acid hydrogen ions flow from the seawater across the membrane, and a voltmeter measures the resulting electric-potential difference compared with the reference electrode. The sensor can use that measurement to calculate the water’s pH: The more H+ ions there are, the more that flow across the membrane, and the greater the resulting voltage. One drawback of pH electrodes, however, is that they’re very sensitive to the presence of other ions in seawater, which can also flow across...

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The Climate-Change Café
Apr24

The Climate-Change Café

Yesterday, I went to an ACS-hosted Science Café at the Marian Koshland Science Museum. The theme of the night was Climate Change, a perfect topic to celebrate the day marking the fifth anniversary of the museum's opening. Andy Jorgensen, on loan from the University of Toledo for a stint at the National Council for Science & the Environment, presented a quick yet complete 45-minute overview of climate change, which is no small feat! The 40 or 50 audience members ranged from local(ish) high school students in Washington for the National Ocean Sciences Bowl to climate policy enthusiasts to economists, all with various levels of knowledge about climate change. Jorgensen, clearly enjoying giving his engaging talk, dove into the audience-participation section of the evening, volunteering students from the audience to represent Peru and China. The average person on Earth, according to data from the Intergovernmental Panel on Climate Change relayed by Jorgensen, is responsible for 4 tons of carbon dioxide emissions per year, through use of vehicles, buildings, food choices, manufacturing of consumer products, you name it. The student on the right is holding up four fingers, to represent the population in China, a country whose people each, on average, emit 4 tons of CO2 per year. The student on the left represents Peru, whose populace only accounts for 1 ton of carbon dioxide per person per year. The U.S.? 20 tons of carbon dioxide per person per year.  That's the equivalent weight of about four adult African elephants, or 1,225,116,904 elephants, just for the U.S. (Only about 2/5 of that number of African elephants exists in the world, however.) Can you imagine all those elephants hovering in the air over the U.S.?  That's a whole heck of a lot of elephants waiting to plummet back down to Earth! Accounting for the increase in elephants... Er, accounting for the increase in carbon dioxide emissions over the decades, the amount of CO2 in the atmosphere has spiked from about 270 ppm in the early 1900s to 385 ppm in 2008. With predictions of the amount of atmospheric carbon dioxide in the range of 525 ppm (if we work hard to reduce CO2 output) to 975 ppm (business as usual) at the end of this century (and corresponding temperature increases of anywhere from 2 degrees Fahrenheit to almost 12 degrees Fahrenheit, and corresponding rises in sea levels), it's no wonder alternative energy and carbon sequestration are all the rage nowadays. After the interactive bits, Jorgensen asked 10 questions to engage the audience in how we as individuals and as a society could impact the ever-climbing levels of greenhouse gases. Here are just a few select questions that I'm curious how C&ENtral Science readers...

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