The Water Column by Luke Cadrin If you live on Cape Cod, you probably know about Nitrogen and the state and towns’ efforts (and price tag) to reduce nitrogen pollution in our environment. You may also have heard about the negative effects of nitrogen pollution on our local waters and the strategies to combat this nutrient overload. However, if you’re like me and struggled through chemistry class, then you may still be wondering what exactly is Nitrogen and what’s the big deal? Here are some of the basics: Nitrogen (N) cycles through our atmospheric, 5. Denitrification: In anaerobic (lack of oxygen) terrestrial, aquatic, and marine ecosystems and is conditions, like waterlogged soil, certain bacteria a necessary building block for life. Most of the N convert nitrates BACK to N gas, allowing the cycle cycle is facilitated by bacteria and cyanobacteria, to begin again. (This is the process happening converting N into biologically available forms and in your Enhanced Innovative Alternative septic back again. This process consists of 5 steps: systems) 1. Fixation: Converting N gas (N ) into biologically 2 - available types of N like nitrates (NO ), nitrites - 3 (NO ) and ammonia (NH ). Most N is “fixed” by 2 3 bacteria, but some is “fixed” by lightning strikes. 2. Nitrification: Bacteria convert ammonium to nitrates or nitrites (the process happening in your Title-5 septic system). Due to their high solubility, much of this leaves the soil and dissolves in the groundwater. 3. Assimilation: Plants can then absorb N + as ammonium (NH ) 4 or nitrate through their roots and create organic forms of N such as amino acids. Animals then consume plants and N cycles through the organisms in an ecosystem. 4. Ammonification: When a plant or animal dies or expels waste, the organic forms of N are broken down back into ammonium by bacteria and fungi in the soil. 12 | Barnstable Clean Water Coalition | Fall/Winter 2025 BCleanWater.org