How Does Pollution Affect Rice?

The agricultural industry is perhaps one of those most directly affected by the onset of climate change, but the chatter surrounding the issue normally focuses on how drought, heatwaves, cold snaps and other unexpected weather events can hinder crop yields. Rarely does it take into account the nutritional impact on foodstuffs of pollution and global warming.

However, a study published earlier this year by Chinese scientists suggests that increased exposure to carbon dioxide could jeopardise the nutritional content of rice. By examining 18 different strains of the Asian staple, the team were able to conclude that pollution led to diminished levels of several key vitamins, minerals and other important nutrients.

Something in the water

Most of the concern surrounding crop sustainability in a climate-changed world has revolved around the use of more environmentally-friendly fertilisers and how to safeguard yields in the face of increasing pollution. Little attention has been given to how existing (and future) levels of pollution can inhibit the nutritional value of foodstuffs upon which we depend.

Seeking to change all that, researchers used the technique of free-air CO2 enrichment (FACE) to artificially expose samples of rice to concentrations of carbon that they would not normally experience. In particular, the scientists tested nine varieties of rice from the Yangtze River delta and a further nine from Tsukuba City in Japan. They were exposed to concentrations of CO2 ranging from 568 parts per million (ppm) to 590ppm, which is representative of the current trend towards 570ppm later this century.

Startling results

The experiment showed a variety of different results, depending on the strain of rice in question and the concentration of CO2 to which it was exposed. However, on average the rice samples lost 17.1% of their vitamin B1 (thiamine) levels, 16.6% of B2 (riboflavin), 12.7% of B5 (pantothenic acid) and 30.3% of B9 (folate). Additionally, the samples showed a 10.3% decrease in protein, an 8% drop in iron and a 5.1% fall in zinc.

The vitamin B deficiencies are particularly concerning since they are incredibly important in maintaining several aspects of a healthy human body. Not only are they instrumental in aiding normal development of the foetus inside the womb, they also improve cognitive function and various other activities performed by the brain.

Dietary diversity

With over two billion people around the world relying on rice as their principal source of food, the news that it may be depreciating in nutritional value is a worrying one. It’s particularly troublesome for the Asian continent, which is home to nine of the 10 biggest consumers of rice worldwide.

With a population of 1.38 billion, China consumes almost as much rice (142,700 tonnes per year) as the next three countries combined (India, Indonesia and Bangladesh). Thankfully, the country appears to have entered a new era in air quality monitoring in order to try and clean up its dreadfully polluted airwaves. Without such action, those dependent on the grain could suffer nutritional deficiencies in the not-too-distant future.