Poisons in the River, Warning of a Green Algae Catastrophe

The installation of weirs has created an environment conducive to the proliferation of green algae by stagnating river flow. The water is blocked and cannot flow naturally, which promotes the growth of green algae.

It is also a severe level, 5 times higher than the recreational activity safety standard of 24 ppb. Currently, ten million people who use Nakdong River water as their drinking water source are exposed to this risk.

Long-term exposure to microcystin can cause liver diseases such as liver enlargement and inflammation, and can even lead to liver cancer. Overseas, if green algae scum is present, access to water, jogging, boating, and fishing activities are completely prohibited, and warning signs are posted. However, in Korea, cruise ship operations and water activities continue without restrictions. Due to a lack of awareness of the dangers of toxic substances, citizens are routinely exposed to them.

The government's response to green algae outbreaks remains at the level of urging restraint, with insufficient practical sanctions or warning signs. The World Health Organization (WHO) recommends 24 ppb as a recreational activity limit, and the United States applies 8 ppb for stricter control. However, in Korea, despite high levels of 120 ppb, cruise ship operations and fishing activities continue, showing a significant gap with international safety standards.

Residents near the Nakdong River tend to accept green algae outbreaks as a routine phenomenon and do not recognize their seriousness. This leads to a dangerous situation where an abnormal environment is perceived as normal. The attitude of residents who take green algae-filled rivers for granted makes problem-solving even more difficult.

Although plants try to block toxic substances, there is growing concern that in excessively polluted environments, toxic substances can transfer to fruits.

It is argued that the green algae in the Nakdong River, along with the inflow of alien species like the moss animal, resulted from the artificial obstruction of river flow by the Four Major Rivers Project.

This is clearly evident in cases where recreational activities continue in places like Hwawon Resort in Daegu, despite the river water being polluted. Over time, memories of the original clean river fade, and the polluted current state becomes the norm, creating a dangerous situation. This shift in baseline hinders efforts to solve the problem by preventing recognition of its severity.

In fact, microcystin has been detected in male semen at infertility centers, confirming infertility-related effects such as reduced sperm motility and count.

Overseas reports indicate that microcystin can spread in aerosol form up to a 10km radius. This means that fishermen, recreationalists, and farmers near the river can be directly exposed. It can pose a particularly fatal risk to young children with weak immune systems and individuals with pre-existing liver conditions.

The proliferation of green algae in river water is strong evidence that the natural flow of the water has been artificially obstructed.

There are four essential conditions for green algae to occur: sunlight, rising water temperature, slow current, and sufficient nutrient supply. In particular, a fast current suppresses green algae growth, but if water is trapped, rivers will also experience green algae proliferation like lakes. This shows that rising water temperatures due to climate change and stagnant currents due to weir construction are major causes intensifying green algae.

Similar to fine dust levels, a system is needed to announce real-time green algae risk concentrations in summer. Intuitive color-based risk grading should be used to help citizens easily recognize the severity of green algae and take action.

Therefore, this issue should not be approached with partisan logic, and basic and metropolitan local government leaders must prioritize citizen health and take responsibility for green algae prevention.

Among these, nutrients and water temperature are difficult to control artificially, but water flow is the only factor that can be controlled by human intervention. Therefore, restoring the river's flow to its natural state and securing water flow is presented as the most practical and effective way to solve the green algae problem.

This is important evidence showing that environmental pollution is not merely a natural phenomenon but directly affects human health.