With summer warmth will invariably come media coverage of massive algal blooms wreaking havoc on our waterways and much talk of phosphorus pollution. Outside of this seasonal notoriety, element 15 gets short shrift in popular culture in comparison to carbon, oxygen, and nitrogen, but it is every bit as essential to life on earth. Without phosphorus, there can be no ATP, the energy currency of the cell, and without ATP there can be no DNA, no RNA, no phospholipid membranes in cells, and no bones in your body.
So from where do your bones come? If you are from the U.S., the likely answer is Tampa.
That is where the Mosaic Company, “the world’s leading producer of concentrated phosphate”, strip mines phosphate rock from shallow deposits laid down by ancient marine sediments laid down before the time Dr. Rittmann was born. The vast majority of the phosphorus produced is used in agriculture, mostly as fertilizer but also as feed ingredients. We get our phosphorus by eating things that have ATP, DNA, RNA, and phospholipid membranes. If you ate dirt, you could get it that way too, but gross.
You may have heard about Mosaic in the news recently. Giant phosphogypsum mounds , or “stacks”, are produced as byproducts of the conversion of phosphate containing ores to phosphoric acid, and these stacks contain radioactive elements and heavy metals. Acidic process water is stored in ponds at the top of the stacks. At Mosaic’s mine in the Bone Valley outside Tampa, a sinkhole formed under such a stack, leaking slightly acidic, slightly radioactive, somewhat metal-contaminated water into Florida’s primary drinking water aquifer during an election year. People became unhappy.
And there begins the story of what I like to call the phosphorus pollution supply chain. At every step of the lifecycle of phosphorus products, pollution is generated. If it’s not at the mine, it’s at the fertilizer plant, or at the landfill, or, most notably, from the agricultural field where phosphorus fertilizer (including manure and biosolids) is applied and can be carried off-field by irrigation water and rainfall. Most of the phosphorus we use is lost to the environment, including to our lakes, rivers, and oceans, where it feeds toxic algae blooms and causes eutrophication.
“Eu” comes from the Greek word for good, which is ironic, because eutrophication essentially means that all the animals that require oxygen suffocate to death.
In the olden days, most people lived on the farms that fed them. Their food waste, human waste, and animal waste was rather efficiently recycled back to the farm in a closed loop, and so was the phosphorus within these wastes. We are far more disconnected from our farms now. Farms need to be highly efficient and centralized in the most fertile regions to meet our consumptive demands in a sustainable fashion. While obviously essential, farms—organic and conventional alike--are by far the largest destroyers of biodiversity on the planet, and if we all tried to live on farms again, they’d destroy even more.
In many ways, cities are our greenest invention, but there are costs. One of those costs is that the old biocycle has become linearized. Instead of wastes returning to their origin, they tend to be landfilled or dumped unproductively (and destructively) into the environment.
As with any complex problem, there is no silver-bullet solution to our phosphorus woes. Mines need to be more efficient at extracting it from ores. Farms need to apply it more judiciously. Animal feed operations need to manage their poop better. Food waste needs to be collected and recycled, and so on. Addressing the phosphorus challenge will take an all-hands-on-deck effort, requiring the collaboration of industry, government, the research community, and environmental watchdogs. To that end, we’ve established the Sustainable Phosphorus Alliance.
The mission of the Sustainable Phosphorus Alliance is to be North America’s central forum and advocate for the sustainable use, recovery, and recycling of phosphorus in the food system. We are a fledgling organization of 9 member organizations and a staff of 1.1, but we’ve only technically been in existence since October. Based on our European analog, the European Sustainable Phosphorus Platform, we bring together organizations (mostly companies and trade associations) from across the phosphorus value chain to network and (soon) to work on targeted projects aimed at decreasing our phosphorus pollution footprint. I’d invite you to find out more about us by checking out our website at phosphorusalliance.org.
What can you do to reduce your own phosphorus use impacts? Probably the best measure is to eat less meat. Plants get phosphorus from the soil, but aren’t 100% efficient at extracting it. Animals get phosphorus from plants and other animals, and they aren’t 100% efficient at extracting it either. These inefficiencies are multiplicative: With every link in the food chain, more phosphorus is lost. Eating plants rather than the animals that eat plants reduces the inefficient use of phosphorus. You can also stop eating altogether, but I wouldn’t advise that.
Another thing you can do is take care when applying phosphorus-containing fertilizers around your yards and gardens. Not all soils require supplemental phosphorus (the P in NPK fertilizers), and there are inexpensive soil test kits available at gardening stores for checking whether you need to apply phosphorus. (I say this without ever having used such a kit myself, but when has that stopped an academic before?) Excess phosphorus can be washed away from your yard by rains then channeled into waterways directly or into the city stormwater system, where it then has to be removed (or not) before being piped to our waterways and aquifers. It’s cheaper and more efficient to not use too much in the first place.
You can also create your own semi-closed loop by composting at home. Compost bins are cheap and easy to build and maintain, and the resulting compost is a great fertilizer for you home gardens. You’d be amazed by how many bags of trash and yard wastes are quickly converted to rich soil in the Arizona heat. As with fertilizer, apply judiciously (e.g. to self-contained gardens). If you really want to be hardcore, you can even install a composting toilet in your home. Don’t do this until you’re married, though, because no one will want to date you.
Of course, if you want to reduce our phosphorus footprint, you can also choose to study these issues and address them via your jobs, whether through academic research or industrial application or government regulation or environmental advocacy.
Finally, you can give the Sustainable Phosphorus Alliance money. Lots and lots of money.