Declining Nitrogen Levels

In News

• According to a new Report, Nitrogen levels are on a decline in the ‘nitrogen-rich world’ and plants and animals may face consequences.

Key Findings

• Imbalance in Availability: 
  • An imbalance in nitrogen availability has been reported across the globe, with some places having an excess and others a shortage of the element. 
• Shrinking Locations: 
  • Nitrogen availability has been shrinking in grasslands in central North America for a hundred years. 
  • Many forests in North America and Europe have also suffered from nutritional declines for several decades or longer due to the same reason.
  • Tropical and boreal forests may be particularly vulnerable.
• Factors responsible for Nitrogen decline:
  • CO2 and nitrogen: Plants grow quickly when exposed to high carbon dioxide (CO2) concentrations. Thus, their demand for nitrogen also goes up.
    • High CO2 levels dilute plant nitrogen, triggering a cascade of effects that lower the availability of nitrogen. 
  • Warming and disturbances, including wildfire.
  • Eutrophication: When excessive nitrogen accumulates in the streams, inland lakes and coastal bodies of water, it could sometimes result in eutrophication
• Negative effects: 
  • Imbalance of nitrogen has been hurting aquatic and terrestrial life that feed on it. 
  • Cattle grazing these areas have had less protein in their diets over time.
  • Slower and smaller growth: Without nitrogen, an essential nutrient, plants grow slowly and produce smaller flowers and fruits. Their leaves turn yellowish and are less nutritious to insects, birds and animals.
  • Insect apocalypse: Plants with low nitrogen levels can encourage swarming in some species of locusts.
  • Low nitrogen availability could limit plants’ ability to capture CO2 from the atmosphere. 
  • Eutrophication leads to harmful algal blooms, dead zones and fish kills.
• Production by Human: Human production of nitrogen is now five times higher than it was 60 years, according to a 2017 study.
• Effects in Human: In humans, high levels of nitrogen in the groundwater are linked to intestinal cancers and miscarriages and can be fatal for infants.

Declining nitrogen in natural ecosystems

• Nitrogen (N) availability is key to the functioning of ecosystems and the cycling of nutrients and energy through the biosphere. 
• The productivity of ecosystems and their capacity to support life depends on access to reactive nitrogen. 
• Over the past century, humans have more than doubled the global supply of reactive N through industrial and agricultural activities. 
  • However, long-term records demonstrate that N availability is declining in many regions of the world. 
  • Reactive N inputs are not evenly distributed, and global changes—including elevated atmospheric carbon dioxide (CO2) levels and rising temperatures—are affecting ecosystem N supply relative to demand. 

Nitrogen Cycle

• It is the circulation of nitrogen in various forms through nature. 
• Nitrogen, a component of proteins and nucleic acids, is essential to life on Earth. Although 78 percent by volume of the atmosphere is nitrogen gas, this abundant reservoir exists in a form unusable by most organisms. 
• Through a series of microbial transformations, however, nitrogen is made available to plants, which in turn ultimately sustain all animal life. 
• The steps, which are not altogether sequential, fall into the following classifications: 
  • nitrogen fixation, 
  • nitrogen assimilation, 
  • ammonification, 
  • nitrification, and 
  • denitrification.

Image Courtesy: Britannica 

Way Ahead

• The strong indications of declining nitrogen availability in many places and contexts are another important reason to rapidly reduce our reliance on fossil fuels.
• Sprinkling nitrogen but at the right time and in the right amount is needed.

Source: DTE