(Roughly) Daily

Protein-packed diets add excess nitrogen to the environment through urine, rivaling pollution from agricultural fertilizers…

In the U.S., people eat more protein than they need to. And though it might not be bad for human health, this excess does pose a problem for the country’s waterways. The nation’s wastewater is laden with the leftovers from protein digestion: nitrogen compounds that can feed toxic algal blooms and pollute the air and drinking water. This source of nitrogen pollution even rivals that from fertilizers washed off of fields growing food crops, new research suggests.

When we overconsume protein—whether it comes from lentils, supplements or steak—our body breaks the excess down into urea, a nitrogen-containing compound that exits the body via urine and ultimately ends up in sewage… the majority of nitrogen pollution present in wastewater—some 67 to 100 percent—is a by-product of what people consume…

Once it enters the environment, the nitrogen in urea can trigger a spectrum of ecological impacts known as the “nitrogen cascade.” Under certain chemical conditions, and in the presence of particular microbes, urea can break down to form gases of oxidized nitrogen. These gases reach the atmosphere, where nitrous oxide (N2O) can contribute to warming via the greenhouse effect and nitrogen oxides (NOx) can cause acid rain. Other times, algae and cyanobacteria, photosynthetic bacteria also called blue-green algae, feed on urea directly. The nitrogen helps them grow much faster than they would normally, clogging vital water supplies with blooms that can produce toxins that are harmful to humans, other animals and plants. And when the algae eventually die, the problem is not over. Microorganisms that feast on dead algae use up oxygen in the water, leading to “dead zones,” where many aquatic species simply cannot survive, in rivers, lakes and oceans. Blooms from Puget Sound to Tampa, Fla., have caused large fish die-offs…

If it’s not one thing, it’s another: “Eating Too Much Protein Makes Pee a Problem Pollutant in the U.S.,” from Sasha Warren (@space_for_sasha) in @sciam.

* Philip Larkin, “Going, Going” (in High Windows)

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As we deliberate on our diets, we might recall that it was on this date in 1888 that Theophilus Van Kannel received a patent for the revolving door, a design that came to characterize the entrances of (then-proliferating) skyscrapers and that earned him induction into the National Inventors Hall of Fame. But lest we think him “all work,” his other notable invention was the popular (at least in the early 20th century) amusement park ride “Witching Waves.”