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Sea acidification on rise, a major global concern

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By: Vijay Kumar

Since the start of the industrial revolution more than a century ago, human activity has led to an increase in the atmospheric concentration of carbon dioxide. The pH of surface sea waters has decreased by 0.1 pH units during this time. The pH scale is logarithmic, so even though this change might not seem like much, it actually represents a thirty to forty percent increase in acidity.

The chemistry of the seawater changes when carbon dioxide is absorbed by the sea from the atmosphere. About forty percent of the carbon dioxide released into the atmosphere is absorbed by the sea. The amount of carbon dioxide absorbed by the sea also rises as atmospheric carbon dioxide levels rise as a result of human activity like burning fossil fuels and altering land use. A series of chemical reactions take place when carbon dioxide is absorbed by seawater, increasing the concentration of hydrogen ions. The effects of this process on the ocean and the marine life it supports are extensive. 7 is the neutral pH on the pH scale, which ranges from 0 to 14. Anything above 7 is considered basic, and anything below 7 is considered acidic. More hydrogen ions equal higher acidity and a lower pH because the pH scale is inversely proportional to the concentration of hydrogen ions. Seawater absorbs carbon dioxide, which is present naturally in the atmosphere. Carbonic acid, a weak acid that dissolves into hydrogen ions and bicarbonate ions, is created when water and carbon dioxide combine.

There is more carbon dioxide evaporating into the sea as a result of human-driven elevated levels of carbon dioxide in the atmosphere. Currently, the sea globally have an average pH of 8.1 which is basic but as more carbon dioxide is absorbed by the ocean, the pH drops and the ocean turns more acidic. The chemical equation for the reaction of carbon dioxide with seawater demonstrates how carbonate ions harm marine life.Fish, crabs, oysters, and other organisms have all perished in seawater with a lower pH over time.

Shells and skeletons may even start to dissolve at too low a pH. The sea butterfly, for instance, is a tiny sea snail the size of a small pea.This sea butterfly is a crucial component of numerous food webs and is consumed by organisms of all sizes, from tiny fish to whales. Shells will slowly dissolves after a few days when placed in sea water that had pH and carbonate levels. Non-calcifying organisms can also exhibit different behaviours as a result of changes in sea chemistry. In more acidic waters, some fish, like clownfish, have a harder time spotting predators. According to studies, larval clown fish’s ability to find suitable habitat is also impacted by low pH levels.

Over the last decade, there has been much focus in the sea science community on studying the potential impacts of sea acidification. Sea Acidification Program serves to build relationships between scientists, resource managers, policy makers, and the public in order to research and monitor the effects of changing sea chemistry on economically and ecologically important ecosystems such as fisheries and coral reefs.

Since sustained efforts to monitor sea acidification worldwide are only in beginning, it is currently impossible to predict exactly how sea acidification impacts will cascade throughout the marine food web and affect the overall structure of marine ecosystems. With the pace of sea acidification accelerating, scientists, resource managers and policymakers recognise the urgent need to strengthen the science as a basis for sound decision making and action. Sea acidification is a problem that impacts the sea ecosystem as well as commercial industries like fishes globally. Therefore, the sincere efforts are needed to reduce sea acidification.

The writer is an Environmentalist


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