Problematic Nitrogen?
R.H. Bennett Ph.D.
Applied Life Sciences LLC
Nitrogen is a fundamental element like Carbon, Oxygen. Nitrogen is a problem, how? It can neither be created nor destroyed but only changed in form (Law of the Conservation of Matter Antoine Lavoisier 1785). All the nitrogen that ever was still is. There will be no more or no less. So how can it be a problem? We shall see it's a problem of distribution and chemical form.
Nitrogen (N) is about 16% by weight of all amino acids and proteins. Amino acids and proteins contain the elements of Carbon, Hydrogen, Oxygen, and Nitrogen (some include Sulfur) If amino acids don't have nitrogen they would not be amino acids and there would be no proteins and no life, period. Proteins are muscle, skin, enzymes, hormones and more. https://ghr.nlm.nih.gov/primer/howgeneswork/protein
The human species goes to great extent to secure protein in the diet. Entire lifestyles and economies are predicated on the acquisition of protein. The human diet must have protein, be it soy, legumes, beef, dairy, fish, and more. The adult diet requires about 46 to 70 grams of protein each day depending on body weight and exercise level. https://www.webmd.com/food-recipes/protein
Imagine the mass of protein that is consumed in Hawai‘i every day. It is here that the law about the conservation of matter is neither created nor destroyed; the law of physics comes in. Proteins get digested, degraded, and metabolized. Proteins are broken down, and the nitrogen remains and must be excreted continuously otherwise the excretion form of nitrogen, urea builds up in the blood and will become very toxic in short order.
All marine life and the occasional human excrete nitrogen directly into the sea. This low level of N is not harmful but beneficial. It is the dose that makes the poison when all of us land-based gritters allow the waste N to migrate to the sea.
Protein nitrogen as urea gets excreted in the urine. Here are the numbers. About 91% of the nitrogen consumed is excreted in the urine. The balance is lost in the feces and sweat (Bingham 2003, Dal Porto 1999).
The Fate of Urine Nitrogen (Dal Porto 1999)
|
Elements (g/ppd)
|
Urine
|
Faeces
|
Urine + faeces
|
|
Nitrogen
|
11.0
|
1.5
|
12.5
|
|
Phosphorous
|
1.0
|
0.5
|
1.5
|
|
Potassium
|
2.5
|
1.0
|
3.5
|
|
Organic carbon
|
6.6
|
21.4
|
30
|
|
Wet weight
|
1,200
|
70-140
|
1,200-1,400
|
|
Dry weight
|
60
|
35
|
95
|
Nitrogen in urine is in the form of urea. Under the effects of environmental bacteria, urea is quickly converted into ammonia. We have all smelled ammonia in urine left to “mellow” in the toilet bowl. Once flushed the urea and ammonia is again acted on by bacteria that convert ammonia to nitrate. This process is called mineralization. Nitrate is salt and entirely water-soluble. Nitrate is very stable and not altered in form again until utilized by microbes and plant life.
Nitrogen Accumulation in the Receiving Waters: From the Table to the Sea
Nitrate by Another Name: Fertilizer
Let's go back to the toilet and follow the N. Not long after the flush, most of the N is urea and quickly converted to the nitrate form. Both urea and nitrate readily dissolve in water. The Black Water or sewage flows into the cesspit, septic leach field or wastewater treatment plant. The nitrate remains unchanged for the most part and flows wherever the wastewater goes.
So where goes the wastewater?
On its way to onsite disposal or the regional treatment plant, it flows in pipes, and these pipes can leak. Sewage water can leak out, and groundwater can leak in when the pressures allow. Thus some nitrate can escape and flow to water.
Once discharged from onsite disposal, a cesspit or septic system wastewater flows downslope along the paths of least resistance until it finds its level and that means groundwater, a stream, including lava tube flows and ultimately to the shore. All along this journey including a very short few days or a long journey of years the water and its nitrate is unaltered by time. There are some people with official titles that tell us that all waste material is broken down in the “soil." The problem is such a claim defies that law. It is the Law of Conservation of Mass says we can only change the form of N. N is indestructible. We shall revisit how a change of form can work in our favor.
Zoom up to about thirty thousand feet and look down at our island. See all the homes and know that all of the homes have an OSDS (on site disposal system) or it is connected via a sewer line to a WWTP (wastewater treatment plant), and all of the urine N flows there. From there it flows wherever the water goes.
According to that State of Hawai’i, there are about 59,000 OSDS in use right now on Hawai‘i Island (Whittier 2009). Applying the watershed studies of Reay (2004) and others, the N in the form of DIN (Dissolved inorganic Nitrogen) ranges from 5.7 to 10.7 kilograms (2.2 lbs. per kg) per household per year. This estimates that somewhere between 740 thousand to 1.4 million pounds of N are flushed into the groundwater connected ocean environment in Hawai‘i Island every year. To conceptualize this, let's call it 1 million pounds per year.
If this much N was contained in 25 lb. bags of fertilizer such as Ammonium Sulfate (25-0-0) that would be 4 million lbs. of fertilizer or 40,000 bags. The site of such dumping into the island shores would be a scandal of unparalleled proportions. That is what is happening along the coasts of this island every year. It is simply out of sight and out of mind.
What all this Nitrogen does to the oceans
Tropical waters are oligo-trophic. By that oceanographers mean the water contains few nutrients. Those that have ever had an aquarium are all too aware of what happens when few nutrients become too many. Water gets cloudy, often green and a water change for the aquarium is the only remedy.
Our ocean is no different, but the water change part is tricky. Water change in the sea can occur when a region is subject to significant currents. The problem being near shore large currents are far less common. The science of Bathymetry reveals the complexities of ocean currents and the notion that the oceans, especially near shore are uniformly mixed is not supported by the scientific data. Sorry, apologists, the solution to pollution is not dilution.
This photo was taken many years ago in Keauhou Bay not far from the boat docks. Visibility was a matter of inches in the summer of 2007. Note the high turbidity and greening of the water. Land use here is high-density dwellings (some sewered) and golf courses.
An extensive study of Keauhou Bay by Dr. D. Mihalka (2015 unpublished data) confirms the turbidity for the inner reaches of the bay.
Coral Takes A Nitrogen Hit Too
Most people aware our coral reefs are very important to Hawai‘i. From the ocean's nursery to the visual beauty that attracts tourist’s worldwide and more, the reefs are Hawai‘i. The value of Hawaiian coral reefs is at least $360 million per year (Cesar 2004). Given itʻs economic, social and cultural value, many argue investment in coral reef protection and conservation is more than justified.
We are painfully aware the reefs are in decline. Warmer waters and increased acidity is killing corals, some more dramatically than others. Carbon dioxide from the combustion of fossil fuels insulates the earth trapping heat. Dissolved in water carbon dioxide forms carbonic acid.
There has been scientific concern that overnutrition of the oceans is also harming corals. Recent research on the corals of Kaneohe Bay confirms our fears. Nitrogen acts synergistically with elevated temperature and acidity to decrease the mineralization of corals (Silbiger 2018). To be simplistic, corals are losing calcium and not gaining it as growing corals do. Human activities have created the perfect storm to degrade corals reefs slowly and along with them all the benefits they provide to the island ecosystem, the oceans, and the lifestyle and economic vitality of Hawai‘i.
We have scant policy and action about waste nitrogen.
The consequences of human activities and nitrogen released into the environment are well documented (Vitousek 1997). He states, nitrogen from human activities “caused changes in the composition and functioning of estuarine and nearshore ecosystems and contributed to long‐term declines in coastal marine fisheries."
In 2008 the National Academy of Sciences, Engineering Challenges report identified the critical need to resolve the mismanagement of nitrogen and provided preventive and remediation recommendations. Those recommendations never found their way through Congress and into policy.
The chasm between science and policy is vast. Congress and the Hawai‘i Legislature are loath to address this problem since it will impact almost everyone’s pocketbook. As a society, we have exploited and reaped financial rewards for a fundamentally no cost nutrient disposal into the environment. The federal subsidies for urban waste management infrastructure are gone, except for a modest loan program.
There is one program and policy in the US Clean Water Act (CWA) called TMDL or Total Dairy Maximum Load. Its purpose is to mitigate pollutant exceedances. For all “Impaired” water bodies with elevated nitrogen levels, the law requires TMDLʻs. However, these programs are not funded by the CWA and on Hawai‘i Island, we have none. None, even though at least 12 nearshore waters are listed as “Impaired” due to nitrogen. Many listed sites are on the ninth anniversary and mitigations remain to be proposed
The EPA delegates authority to the state to administer the CWA. Its provisions are not discretionary. Just the same the State refuses to require TMDLʻs for impaired coastal waters of Hawai‘i Island. As citizens, ignoring Federal Law has dire consequences. The state. however is let off the hook, to the detriment of our resources.
Nitrogen Changing Form to the Rescue
Remember the law, Conservation of Mass? We cannot destroy nitrogen, but nature changes its form all the time. There is something called the Nitrogen Cycle, and its form changes naturally as it must.
In water, nitrate excess is the problem. So how do we get it out? Converting nitrate to something else chemically is possible but on a watershed scale impractical and cost prohibitive. However, at the site of nitrate formation, nature shows a way.
Denitrification is the solution. It occurs naturally in wetlands. This environment provides a niche for bacteria that need very little atmospheric oxygen. Their microbial metabolism still needs some oxygen. So bacteria that can grow in the absence of dissolved oxygen in water can strip oxygen from compounds that carry it. One such compound is nitrate. Each molecule has three oxygen’s attached to it. The anaerobic bacteria can strip off the oxygen’s and in so doing two atoms of nitrogen immerge as the gas N2. The gas floats away and joins the N2 in the atmosphere. This process is bacterial denitrification.
In Westbrook CT, they are testing a modified septic system leach field, expected to remove about 64% and more of the nitrogen using this natural process. It is not likely to add much cost to a new septic system. It is a simple 12-inch layer of soil and sawdust or any other finely ground source of plant cellulose. The cellulose is a carbon source for the denitrifying bacteria. In similar versions with a greater anaerobic area, researchers report a 90% reduction in nitrate nitrogen. Note the nitrogen gas returning to the atmosphere. It makes up about 80% of the air we breathe and it is NOT a Greenhouse Gas.
Now that the box is broken wide open, it will be easier for folks in Hawai‘i to begin thinking outside of it and take action.
Our keiki and the corals will thank you.
Malama Pono
References
Bingham, Sheila A. "Urine nitrogen as a biomarker for the validation of dietary protein intake." The Journal of nutrition133.3 (2003): 921S-924S.
Dailer, Meghan L., et al. "Using δ15N values in algal tissue to map locations and potential sources of anthropogenic nutrient inputs on the island of Maui, Hawaii ‘i, USA." Marine Pollution Bulletin 60.5 (2010): 655-671.
Del Porto D, Steinfeld C, 1999. The Composting Toilet System Book, Center for Ecological Pollution Prevention, Concord, Mass.; Drangert J-O, Bew J, Winblad U, 1997. Ecological sanitation: Proceedings from Sida Sanitation Workshop, Balingsholm, Sweden.
Cesar, Herman SJ, and Pieter van Beukering. "Economic valuation of the coral reefs of Hawai'i." Pacific Science 58.2 (2004): 231-242.
Laws, E. A., et al. "High phytoplankton growth and production rates in oligotrophic Hawaiian coastal waters1." Limnology and Oceanography 29.6 (1984): 1161-1169.
National Academy of Sciences. Grand Challenges for Engineering. In: National Academy of Engineering Summit Series - Face the Challenge National Academy of Engineering (NAE). 2008.
Ringuet, Stephanie, and Fred T. Mackenzie. "Controls on nutrient and phytoplankton dynamics during normal flow and storm runoff conditions, southern Kaneohe Bay, Hawaii." Estuaries 28.3 (2005): 327-337.
Silbiger NJ, Nelson CE, Remple K, Sevilla JK, Quinlan ZA, Putnam HM,
Fox MD, Donahue MJ. 2018 Nutrient pollution disrupts key ecosystem functions on coral reefs.
Proc. R. Soc. B 285: 20172718.
Vitousek, Peter M., et al. "Human alteration of the global nitrogen cycle: sources and consequences." Ecological Applications 7.3 (1997): 737-750
This is published with Commons Attribution and may be used freely. Please cite as RH Bennett PhD, Problematic Nitrogen, Healthy Hawaiian Oceans www.h20kona.org
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