Ocean Acidification & its Causes

According to a recent survey, the researchers say that the color of over 56% of the world's oceans, larger than Earth's total land expanse, has changed significantly over the last two decades, color is changing from blue to green.

Reasons behind this:-

1. Climate Change

2. Global Warming

3. Increasing Temperature

4. Increase in the number of Phytoplanktons and Zooplanktons

5. Eutrophication

6. Algal Bloom

Q) What is Eutrophication?

Coastal waters are also affected by excess nutrient inputs, mostly nitrogen, from agriculture, fertilizers, and sewage. The resulting eutrophication leads to large plankton blooms, and when these buds collapse and sink to the sea bed, the subsequent respiration of bacteria decomposing the algae leads to a decrease in seawater oxygen and an increase in Carbon di-oxide (a decline in pH).

Effects of it:-

1. Color reflects the state of the ecosystem

2. Color changes mean its impact on the ecosystem also changes

3. The marine food web gets disturbed

4. The marine body gets too polluted

5. Biological Oxygen Demand (BOD) level decreases

6. Impact on a significant amount of oxygen we breathe

7. A crucial part of the Global Carbon Cycle

8. A foundational part of the ocean food web.

• Oceans are an important reservoir of Co2, absorbing a significant quantity of it almost 1/3rd produced by anthropogenic activities and effectively buffering climate change.

• Ocean Acidification is the change in Ocean chemistry- lowering of ocean pH (i.e. increase in concentration of hydrogen ions) driven by the uptake of carbon compounds by the ocean from the atmosphere.

• As the uptake of atmospheric Co2 by the ocean increases, the concentration of hydrogen ions in the ocean increases, the concentration of carbonate ions decreases the pH of the oceans decreases and the oceans decreases and the oceans become less alkaline- this process is known as Ocean Acidification.

Carbon-dioxide effects on Ocean Acidification:-

• The uptake of atmospheric Carbon-dioxide is occurring at a rate exceeding the natural buffering capacity of the ocean.

• The pH of the ocean surface waters has decreased by about 0.1 pH unit (i.e. 26% increase in ocean hydrogen ion concentration since the beginning of the industrial revolution.

Why do we refer to it as Ocean Acidification?

• That is because acidification is the direction of travel, the trend, regardless of the starting point. Acidification refers to lowering pH from any starting point to any endpoint on the scale.

• Acid rain can have a pH between 1 and 6 & has an impact on surface ocean chemistry. It has a major effect on ocean acidification locally and regionally but is very small globally.