Nitrous oxide is also known as laughing gas. Nitrous oxide can be mixed up with nitric oxide (NO) or nitrogen dioxide (NO2). None of them are greenhouse gases, but they are part of creating tropospheric ozone, which is a greenhouse gas. Nitrous oxide is a chemical that is made of an oxide of nitrogen, and its formula is N2O. N2O is at room temperature in its gaseous formula, it is colourless, and it has a slight sweet scent and taste. N2O is commonly used in medical purposes, especially in surgery and dentistry, because it helps to reduce pain. It is called a “laughing gas”, because, when you inhale it, it gives you an euphoric feeling. It is also used in rocket propellants and in motor racing engines because it is an oxidizer, which helps the engines work more powerfully. N2O is the third-most important greenhouse gas, and it is mostly released into the atmosphere from agriculture.

N2O can be released into the atmosphere naturally and from human activities. Naturally, N2O is released into the atmosphere from microbial activities in soil and in the ocean. Anthropogenic N2O is released into the atmosphere mainly because of fossil fuels, biomass burning, industrial production of nitric acid, and the application of fertilizers to agricultural crops. Nitrous oxide acts around the Earth in the same way as methane and carbon dioxide. It captures re-radiated infrared radiation from the Earth’s surface. N2O stays in the atmosphere for around 120 years.

N2O emissions have been rising because of human activities, and they have been raised by over 30% in the last four decades. During the industrial era, carbon dioxide has caused about 10 times more warming than nitrous oxide. N2O is more powerful because around 500 grams of the gas warms the atmosphere 300 times more than the same amount of CO2. N2O also affects the ozone layer.

N2O levels in the atmosphere are mainly increasing because of the world’s population growth. The growing population needs more food, and by producing food, we use more fossil fuels to grow the crops. Also, for growing crops, farmers use fertilizers, the fertilizers that plants don’t use are sinking into the soil. Also, cattle farms are responsible for the release of N2O into the atmosphere because cows emit N2O directly from their manure and through fertilizer emissions from the grains that they are fed. So the fastest-rising emission rate is in these countries, which are producing most of the food. For example, in Brazil, fertilizer usage has increased by half since 2005.

Wastewater treatment produces N2O as a byproduct when activated sludge processes are used to speed up the decomposition of waste. In the United States, wastewater treatment accounts for six percent of human-caused nitrous oxide emissions. The amount of N2O emitted by wastewater treatment plants can vary greatly. Lower levels of ammonia and nitrite in the treated wastewater can reduce nitrous oxide emissions. Treatment plants aim to remove nitrogen from the water, which is found in wastewater as ammonium. During the nitrification and denitrification processes, biological nutrients are removed from the wastewater, but nitrous oxide is released. If the nitrification process is not complete, nitrite levels can rise, leading to higher nitrous oxide emissions. Implementing effective strategies to mitigate nitrous oxide emissions at wastewater treatment plants is still uncommon, mainly because their effectiveness is uncertain.

In conclusion, agriculture is one of the best ways to lower the N2O level in the atmosphere. Farmers have to lower their usage of chemical pesticides. Instead, they can use biological pesticides. For more reasonable wastewater treatment, appropriate concentrations of dissolved oxygen and balanced bacterial feeding can be used. The other sources for increased N2O are transportation, stationary combustion, and industrial production.

Sources:
https://en.wikipedia.org/wiki/Nitrous_oxide
http://www.soest.hawaii.edu/mguidry/Unnamed_Site_2/Chapter%202/Chapter2C3.html
https://news.stanford.edu/2020/10/07/laughing-gas-growing-climate-problem/
https://www.eesi.org/articles/view/laughing-gas-is-no-joke-the-forgotten-greenhouse-gas