- Aral Sea
- Black Sea
- Lake Baikal
Select the correct answer using the code given below:
(a) 1 only
(b) 2 and 3 only
(c) 2 only
(d) 1 and 3 only
Answer: (a)
Option (a) is correct: Decades ago, the Aral Sea was the world’s fourth largest body of inland water, but it has shrunk immensely due to diversion of rivers for irrigation (human activities). Two decades ago, it split into the small northern and larger southern sections, and further divisions have been happening ever since. Moreover, in the 1960s, the Soviet Union undertook major water diversion projects on the Syr Darya and Amu Darya rivers, capturing water that once fed into the Aral Sea. Dust blowing from the exposed lakebed eventually degraded the soils, forcing further water diversion efforts to revive them. On a larger scale, loss of the Aral Sea’s water influenced regional climate, making the winters even colder and the summers much hotter. Fifty years later, the lake is virtually gone. Black Sea is often seen in the news in the context of Russian affairs. Past 60 years, the oxygen rich top layer of the Black Sea decreased from 140 metres to 90 metres deep, which amounts to an over 40 percent dip in habitable waters. Two existing causes behind the shrinkage: an abundance of nutrients, particularly algae that led to great consumption of oxygen and global warming. With warmer winters, there is a lower volume of dense water created and this lowers the oxygen content. Warmer waters also mean the sea is now able to accumulate less dissolved gas, including oxygen. The Black Sea has lost more than a third of its habitable volume. The Habitable area in Black Sea is shrinking, but the actual volume is not shrinking immensely. In 2015, Russia officially declared Lake Baikal an emergency zone because of a catastrophic drop in its water level. Baikal is the globe’s largest freshwater lake and is on the UNESCO World Heritage list. Industrial area of the closed Baikal Pulp and Paper Mill that has been polluting the lake for decades. building more hydroelectric dams near Lake Baikal can cause the unique lake to dry out. It is shrinking but the fate is not immense. It is not dried up.
