Stories tagged nutrient-loading

Sep
23
2010

You might be aware of phosphorus, P, as a key ingredient in your lawn fertilizer. Or, perhaps you’ve seen “Does not contain phosphates” labels on your household detergents. If you haven’t seen these labels yet, chances are high you’ll see them soon. Why??

Phosphorus is Useful as Fertilizer and Detergent...

Fertilizer with P: See the N-P-K?  The P stands for phosphorus.  The number 21 below it tells us the percent of P in the fertilizer.  Many lawn fertilizers are now 0% P.
Fertilizer with P: See the N-P-K? The P stands for phosphorus. The number 21 below it tells us the percent of P in the fertilizer. Many lawn fertilizers are now 0% P.Courtesy Malawi MV project work

Phosphorus is a life-supporting mineral, which is why so many fertilizers contain it. Phosphates, the naturally occurring form of phosphorus, help soften water, form soap suds, and suspend particles making them choice detergents. Supporting life and keeping clean would normally be good things, but phosphorus has a dark side too.

... But, Phosphorus Causes Smelly, Dead Eutrophication

Because phosphorus is so good at growing stuff, it is actually harmful to the environment when it becomes dissolved and concentrated in bodies of water. Phosphorus-rich lakes cause algae blooms – huge increases of algae in a short period of time (kind of like the post-World War II Baby Boom, but for algae). Besides being smelly and turning water green, algae “breathe” the oxygen right out of the lake! Stealing dissolved oxygen even in death, algae create hypoxia – low oxygen, which prevents most other living things from surviving in the surrounding area. This whole process, from phosphorus-loading to algae bloom to hypoxia, is called eutrophication. There are other environmental and health risks to phosphorus, but eutrophication is what politicians are talking about around the water cooler these days.

Icky Algae Bloom: Algae blooms occur in nutrient-loaded water bodies and often led to hypoxia in a process called eutrophication.
Icky Algae Bloom: Algae blooms occur in nutrient-loaded water bodies and often led to hypoxia in a process called eutrophication.Courtesy Felix Andrews

Seventeen States Banned Phosphorus in Automatic Dishwashing Detergents

Deciding that euthrophication was yucky, in July, 17 states, including the entire Great Lakes Commission of which Minnesota is a member, passed laws banning phosphates from automatic dishwasher detergent. That might not seem like a big deal, but automatic dishwasher detergent is said to comprise between 7-12% of all the phosphorus making it into our sewage system (source). Previous legislation has limited or banned phosphorus in lawn fertilizers and laundry detergents.

Consumers Asked to Cope

According to a recent New York Times article, some consumers are getting their feathers ruffled as detergent manufacturers re-do their formulas to comply with state laws. The primary complaint is that the phosphate-free detergents don’t clean as well as traditional formulas. Consumer Reports concurred: of 24 low- or no-phosphate detergents tested, none matched the cleaning capabilities of detergents with phosphates. It may be uncomfortable at first, but learning to cope in a low-phosphorus world is already having environmental and human health benefits.

Green Cleaning: There are several line of green cleaning products that contain low- or no-phosphates.
Green Cleaning: There are several line of green cleaning products that contain low- or no-phosphates.Courtesy Becoming Green

Rest assured, industry officials still want your business and are continually improving their formulations. Indeed, the same Consumer Reports article mentioned above rated seven low- or no-phosphate detergents as “very good.” For the curious, there is a multitude of other websites reviewing phosphate-free detergents online. Pre-rinsing and/or post-rinsing have also been cited as ways to deal with phosphate-free dishwashing detergents.

Peak Phosphorus: Another Consideration

If you still aren’t convinced of the switch, consider this: we’re running out of phosphorus like we’re running out of oil. Phosphorus is a mineral, mined from naturally occurring phosphates, and we’re mining it faster than geologic cycles can replenish it. One Scientific American article cites the depletion of U.S. supplies in a few decades (world supplies may last for roughly another 100 years) given current consumption rates. Without phosphorus, world food production will plummet and with a global population soaring towards 9 billion people, that would be a very sorry state of affairs. If we succeed in limiting our phosphorus consumption, say, through eliminating it from household detergents, we may be able to continue using it in fertilizers and thus keep the human population fed well into the future.

What do you think? Is the phosphate-ban worth it?