Stories tagged hypoxia

Thanks to record flooding in the Mississippi River, this year's Gulf of Mexico dead zone could exceed 2002's whopping 8,400 square-mile bout of hypoxia.

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?

Jul
28
2006

Scientists are studying a 70-mile "dead zone" off the coast of Oregon.

First noticed in 2002, the dead zone is larger this year than in previous years.

What is a dead zone? It's an large area of water that's very low in oxygen and can't support life. (Scientists call this "hypoxia.") Dead zones are caused by the explosive growth of tiny aquatic plants called phytoplankton. When the phytoplankton die, they are decomposed by bacteria. Massive numbers of bacteria use up the oxygen in the water. Any animals that can swim out of the low-oxygen water--like many fish--do so. Others--some fish, many crabs, and others--suffocate because they can't get enough oxygen to live.

Dead crabs: Dead Dungeness crabs on beach, Oregon Coast (Photo by Jane Lubchenco)
Dead crabs: Dead Dungeness crabs on beach, Oregon Coast (Photo by Jane Lubchenco)

In this case, the phytoplankton blooms are caused when north winds cause upwelling in the water column. The cooler water is rich in nutrients, providing a feast for the phytoplankton. When the wind dies down, the upwelling stops, and many phytoplankton die a natural death. Their decomposition results in water that is deadly because it lacks oxygen needed for life.

This year, the upwelling started in April, stopped in May, and started up again in June. The off-and-on upwelling creates a thick mat of organic material that rots and uses up the oxygen in the water. Then, when a new upwelling occurs, the oxygen-depleted water moves toward shore, killing the plants and animals that can't get out of its way.

Measuring oxygen levels: Chris Holmes (left) and Dr. Francis Chan (right), PISCO researchers measuring oxygen levels off the Oregon coast from the OSU research vessel Elakha (Photo by Jane Lubchenco)
Measuring oxygen levels: Chris Holmes (left) and Dr. Francis Chan (right), PISCO researchers measuring oxygen levels off the Oregon coast from the OSU research vessel Elakha (Photo by Jane Lubchenco)

So, why the upwelling? Jane Lubchenco, professor of marine ecology at Oregon State University and a member of the Pew Oceans Commission, told the Associated Press:

"We are seeing wild swings from year to year in the timing and duration of the winds that are favorable for upwelling. ... This increased variability in the winds is consistent with what we would expect under climate change."

Global warming is also the suspect in dead zones off Namibia, South Africa, and Peru.

(The dead zone in the Gulf of Mexico at the mouth of the Mississippi River is caused by agricultural runoff containing fertilizers. The river carries all those nutrients into the Gulf, creating algal blooms that use up all the oxygen.)