[Reading Science] Acid Rain and Acid Snow... An Era Where Memories Disappear

Acid rain kills trees and turns the soil into a desert.
[Photo by YouTube screen capture]

[Asia Economy Reporter Kim Jong-hwa] Recently, there has been a considerable amount of winter rain. Many people think positively that fine dust is being washed away. However, there are people who get caught in this rain with their bare bodies.

When the amount of rain is small, quite a few people just walk around getting wet, but this can be considered a foolish act of exposing one’s body directly to acid rain. If you think that fine dust particles, in other words, various heavy metals clumped together in water droplets, are falling on your head, shouldn’t your response be different?

Acid rain refers to rainwater that has absorbed sulfuric acid or nitric acid formed when air pollutants meet water vapor in the atmosphere. Normally, rain has a slightly acidic pH of about 5.6 to 6. The pH indicates acidity: values less than 7 are acidic, 7 is neutral, and values greater than 7 are alkaline (basic). In other words, the smaller the number, the stronger the acidity.

Acid rain’s pH drops to between 4 and 5 due to the formation of sulfuric or nitric acid. In South Korea, rain with a pH below 5.6 is defined as acid rain. This is because the weak acidity of carbonic acid, formed by carbon dioxide (CO2), saturates and maintains equilibrium at about pH 5.6. Some countries define acid rain as rain with a pH of 5.0 or lower.

Acid rain can be considered a major cause of desertification. Acidic substances cause nutrient deficiencies, leading to trees drying up and dying, accelerating desertification. Fine dust containing high levels of sulfur dioxide (SO2) or nitrogen dioxide (NO2) in the atmosphere causes acid rain, acidifying soil, seas, and lakes. This results in soil and marine and lake degradation, ecosystem destruction, and forest dieback.

Acid rain and acid snow are gradually eroding our precious cultural heritage, the Seokgatap and Dabotap pagodas.
[Photo by YouTube screen capture]

When heavy metals such as cadmium in the air combine with fine dust and fall as rain, damage to crops, soil, and marine life is inevitable. Additionally, fine dust contained in acid rain attaches to plant leaves, blocking stomata and interfering with photosynthesis, which delays crop growth.

Damage to cultural assets cannot be ignored either. Strong acid rain corrodes limestone and marble. This leads to damage to artworks and cultural properties of high cultural value, resulting in economic losses.

The U.S. Forest Service conducted a study over more than 30 years since 1989 on a 34-hectare forest area within the Appalachian Mountains to examine the effects of acid rain on forests. The study confirmed that acid rain increases water absorption by vegetation, altering the Earth's water cycle and negatively affecting the global biological ecosystem.

Professor Li Xin Wang, an ecologist at Indiana University who led the research, pointed out, "Not only forest trees but all plants on Earth respond sensitively to acidification, adversely affecting the biogeochemical cycles of water and energy that have been stably maintained until now. Acid rain negatively impacts the water cycle structure that forms the basis of ecosystems, promoting drought and ultimately triggering desertification, which devastates the lives of humans and animals alike."

What are the measures to reduce acid rain? Strong regulations, of course. Recently, emissions of acidic substances from car exhaust and factories have significantly decreased. This is because the installation of catalytic converters at emission outlets has been mandated, converting highly toxic nitrogen oxides into less toxic nitrogen and oxygen.

These days, you must make sure that snow and rain falling in winter do not touch your skin at all. Sharing warmth by covering each other with small umbrellas, the days when people caught falling snow with their mouths are just a scene left in old memories.
[Photo by YouTube screen capture]

In the United States, the Clean Air Act was amended to force a 50% reduction in annual sulfur dioxide emissions. As a result, over the past decade, the pH value in the eastern U.S. has increased from 4-5 to about 5.

Even though the pH value has improved compared to the industrialization era, it is by no means desirable to get soaked in acid rain combined with fine dust during winter. If you get caught in acid rain that corrodes metal sculptures with your bare body, you cannot avoid hair loss and skin diseases. Fine dust is scary, but acid rain should also be feared.

Snow and rain falling these days are all acid snow and acid rain. Just a few years ago, the acidity of snow in some regions reached a pH of 3.9. This level of acidity is comparable to vinegar. The pure white snow falling in winter should be seen as similar to transparent vinegar droplets clumped together.

As long as fine dust does not disappear worldwide, acid rain and acid snow will inevitably continue to fall. The romantic era when people strolled down leaf-strewn streets in the rain or caught snowflakes in their mouths is just a nostalgic memory. Lovers cannot even share one umbrella to avoid the rain anymore. We have entered an era where everyone must cover their bodies with large umbrellas when it rains.