It's nearly August and, in the Northern Hemisphere, that means the emergence of the red tide in lakes, steams and oceans. The red tide is actually a swarm of an organism, often called red algae, although, in truth, it is a cyanobacteria and not really algae. Both cyanobacteria and algae are everywhere in our water. Most of them are beneficial. Some, however, produce toxins. The toxins the cyanobacteria called red algae produce are called cyanotoxins. Given nutrients, these species double in size in as little as 24 hours. They all, algae and cyanobacteria like, love nitrogen, and our civilization is feeding it to them. The United States Geological Service estimates 153,000 metric tons of "nutrient" -- meaning nitrates and phosphates -- have been sent out into the Gulf of Mexico from the mouth of the Mississippi this year. The dead zone which results from this now covers an area the size of Connecticutt.
But closer to home for most of us, our lakes are seeing the red tide, arising from the same flow of nutrients from our collective ass into the waters of our nation. An artificial ecology is afoot, and these critters are responding according to their nature. It so happens an agricultural practice exists which can turn that tide and introduce a negative feedback loop into this brave new ecology of our creation: fields of algae. The best of breed of these technologies is called algal turf scrubbers (ATS), invented in the 1970s by Dr. Walter Adey of the Smithsonian Institution. Now field tested and proven for over thirty years, it exemplifies the opportunity to unleash our farmers in the quest to turn the red tide back everywhere.
Dead zones at the mouth of rivers and algae blooms in lakes arise from a similar phenomenon -- the nitrogen and phosphorus we are adding to the natural levels throughout the watershed. We do this in two modes: the effluent from sewer and industrial pipes into streams (called point sources); and in runoff from our fields and buildings and parking lots, as well as septic tanks (called non-point sources). The EPA has a website, and most states do as well (here is Iowa's web portal to the database), publishing the monthly average output of ammonia, nitrogen and phosphorus from point sources. Regulated under the National Pollution Discharge Elimination Program (NPDES), each point source needs a permit from the EPA and must report regulated substances in waters they discharge to surface waters of the United States.
When the Clean Water Act created the NPDES program, Congress made the EPA have direct authority only over point sources. Non-point sources are regulated by individual states. The battle over this line has raged for decades. Agricultural interests maintain that runoff from farm fields is negligible when fertilizers are applied properly. But "properly" is a dicey term. Many factors are out of the farmers' control. If a gully-washer hits right after application, the soil bacteria and other processes will not have time to convert the ammonia applied into the form of nitrogen the plants will need.
The combination of a drought last year and gully washers this year sent the nitrate levels in the Raccoon and Des Moines River watersheds through the roof this year. In Iowa, the Des Moines Water Works had to use expensive technology to keep nitrates down to 10 ppm, and 3 ppm is the actual level we should be shooting for. The USGS is reporting record nutrient levels hitting the Gulf. We've got red tides everywhere we look in our lakes and ponds. A major battle is being waged in Iowa to somehow regulate non-point sources, but this deadlock has lasted decades and has a lot of intertia.
An Artificial Ecosystem Emerges
It is ironic, but our overuse of fertilizer and lack of control over sewage systems for our growing populations have made our river waters take on attributes of soils. Now these waters can be farmed to produce biomass, and produce it in droves. The "sweet" algae in these fields take up the nitrogen and precipitate the phosphorus out as crystals because these algae are rooted in the mat material and can double in mass each 24 hours.
As a result, the "sour" algae (actually, cyanobacteria in most cases, which people call algae) are starved, Pond scum (which are algae) and cyanobacteria form in suspension without roots in lakes. Some of them produce toxins. All these species love nitrogen. They double in mass in 24 hours if they have enough of it. We can enlist "sweet" algae, which we harvest and use, to starve out the "sour" algae waiting to express themselves downstream, including red tides.
Many species of algae root and grow colonies in one place. These algae (called benthic algae) can be farmed just like any other kind of hay on land. By harvesting these plants weekly, or even daily, we remove nitrates and phosphates from the water, carbon from the air and add back oxygen to the water. This quadruple threat to sour algae's environment can be used to starve them and avoid the emergence of red tides.
Benthic algae find root in algal fields and grow in place. They can be tended, weeded and harvested efficiently. The colonies form a turf covering the ATS mat in which their roots are embedded. They double in mass every 24 hours, if the nutrients are rich enough. Thus ATS is an agricultural technology and practice which grows turfs of benthic algae in order to scrub water of nutrients.
Fields Of Algae
A loose-knit group of collaborators I stumbled upon are working on a technology invented in the 70s called algal turf scubbers. Various designs have been built and harvested for thirty years now, including a 1440-acre site in Florida. This agricultural technology involves special mats affixed to the surface of a shallow trench over which river water is diverted and returned to the stream at the end. In between, "sweet" algae naturally root and grow. All these species of algae are in the water at a given time. What matters is which of them respond to increases in nutrient levels in the water. We can capitalize on that to suppress red tides and other species with toxic effects on us.
The political changes we need to encourage wide adoption of agricultural technologies like this are nutrient credits (note: PDF). Florida has them, but many areas of the nation (like the Midwest) do not. This bounty on each pound of nitrogen and phosphorus makes algal turf fields quite economic for farmers and even municipalities to make and manage. A University of New York - Buffalo researcher just led a team building one with parts from Home Depot.
These scientists are actually working on the next generation of this technology, and wonder why farmers and agribusinesses have not capitalized on the current generation, now well-proven. That question has caused many more of us to get involved and think about how to promote the technology to the people who could profit from it, and benefit the commuity (and the planet).
It's ironic that we would evolve new agricultural technology based on waste and disaster on land that can grow biomass from river water, but there it is. Now that that is the reality throughout most of our nation, we need to respond in many ways.
Making Money Doing Good
My small part in this discussion is modeling to look at the question of whether biomass production itself could be economic because of the sheer volume each acre of a algal field can produce. The USGS reports that 153,000 metric tons of nutrients will go out the mouth of the Mississippi this year, 58,000 metric tons in May alone. 65% of that nutrient is from non-point sources, they estimate. If all of that was captured in algal fields, it would produce 2,000,000 metric tons of biomass -- much more than the combined biomass of all other crops produced in the Mississippi River Valley.
What really caught my imagination was a discussion with a scientist who went to one of these fields and said, "The water at the end fizzed with oxygen." That really blew my mind. He explained the algae break carbon dioxide and take the carbon for themselves while releasing the oxygen back into the water. It also raises the pH of the water, making it less acidic. In turn, the higher pH causes phosphates precipitate out of the water onto the turf of "sweet" algae, and is harvested along with the algal stalks each week, so the resulting slurry has high nitrate and phosphorus content.
Imagine what effect that much oxygen would have downstream. Imagine how natural biocosms long suppressed by the combination of low oxygen and high nutrient loads in the water could respond. Imagine making a dent on red tides and dead zones, and stimulating nature to do even more than it can right now.
Farmers can literally exploit the nutrients upstream from them, whatever the source, to produce a bumper crop of hay. They can apply it to their own soil to reduce erosion, replace applied fertilizer and build the top soil back up after decades of erosion. They can use the biomass for ethanol, biogas, biochar, compost and livestock feed. If the right species of algae are present, they can sell to biodiesel plants and many other existing industries which can use benthic algae as feedstock. And, in the end, release hyperoxygenated water back into the stream scrubbed of nutrients.
Ecologies are difficult to model. We are using systems dynamics models and lots of spreadsheet grids, but nature is always more varied and nuanced than we can model -- human nature even more so. But we need to respond to the nutrient levels in our rivers and lakes and into the ocean. We need to reduce what we can and harvest what we can. I think if we were raising the oxygen levels in water coming back into the river that biological communities which have been suppressed by the high nutrient levels and low oxygen will respond, thus amplifying what little we can do. Even in artificial ecologies, maybe we can find symbiosis by introducing new feedback loops and balance out a portion of our effect on our environment.
Maybe it could make a dent. I don't know. But this crisis is real, and we need to address it, every one of us.
H/t to JaxDem for their diary on the red tide in Florida, and for recommending I diary on this technology.
Thanks so much to the community for throwing a spotlight on this diary!