The Associated Press reported on December 19, 2022, that aquatic scientists were developing a system that would be capable of measuring the carbon dioxide and pH levels (the measure to gauge acidity) of Great Lakes of North America over several years. The Great Lakes comprise five lakes—Lake Superior, Lake Michigan, Lake Huron, Lake Erie, and Lake Ontario—and contain one-fifth of the world’s total freshwater. These lakes have been getting acidified due to the increasing amount of carbon dioxide in the atmosphere and carbon-laden water runoffs from land. The acidification of these lakes is not a good phenomenon because they serve as the habitat for more than 3,500 species of plants and animals.
In order to measure exactly how much these lakes are turning acidic, two sensors were attached to a floating weather buoy by the scientists on Lake Huron, the third largest freshwater lake in the world after Lake Superior and Lake Victoria, which measured CO2 pressure and pH level in the water column. Interconnected bodies of water, these lakes are straddling the US-Canada border and drain into the Gulf of St Lawrence in the North Atlantic, through the St Lawrence river.
Reasons for Acidification
The acidification of oceans occurs when the levels of carbon dioxide from the atmosphere increase. Initially believed to be a good phenomenon, increased absorption of carbon dioxide in water bodies changes the chemistry of the waterbodies and the water begins turning into carbonic acid.
According to the National Oceanic and Atmospheric Administration (NOAA), in the past 200 years, the levels have fallen by 0.1 pH units, leading the ocean water become 30 per cent more acidic. The scientists also found that this phenomenon is not just limited to oceans but extends to all water bodies. As per the recent findings, even the Great Lakes might approach acidity at around the same rate as the oceans by 2100.
The Study
Some computer modelling studies suggest that atmospheric carbon might turn the Great Lakes and other freshwater bodies more acidic. However, trends in the pH levels of the lakes could not so far been detected for lack of any long-term monitoring programmes. The Lake Huron project is expected to do that. Scientists, for this purpose, have attached two sensors to a floating weather buoy on Lake Huron at the Thunder Bay National Marine Sanctuary near Alpena, Michigan. One of the sensors would measure the carbon dioxide pressure in the water column; and the other, the pH. The sensor would also measure the carbon dioxide and pH levels in other Great Lakes over many years. The crews are also collecting water samples at varying depths for chemical analysis, within an 11,137 sq. km area.
About Great Lakes
According to the NOAA, the Great Lakes are believed to have been born about 20,000 years ago, when the Earth began to warm up, and water started melting from the glaciers and filled the basins on its surface. This rich ecosphere has been under threat as the five lakes might witness a pH decline of 0.29–0.49 pH units, by 2100. According to NOAA’s Ocean, Coastal and Great Lakes Acidification Research Plan, 2020, the Great Lakes may probably become more acidic assuming the current projections of anthropogenic carbon dioxide and constant alkalinity.
Impact of Acidification
It is not easy to determine the precise consequences of the rise in the acidity of the Great Lakes in the absence of data. Acidification not only endangers coral reefs but also other marine life. Increased acidification may completely lead to the extinction of marine life, resulting in major changes. As per the scientists, acidification may also lead to decrease in native biodiversity, create physiological challenges for organisms, and may permanently alter the structure of the ecosystem, severely impacting the hundreds of wooden shipwrecks that are believed to be buried in the bottom of these lakes.
Aquatic researchers at Ruhr University, Bochum, Germany, studied four German reservoirs in 2018. They found that the pH levels of the reservoirs had declined three times faster in 35 years than in oceans, since the Industrial Revolution. As a result, the ability of water fleas to defend themselves against predators was compromised and a similar trend might be seen in the Great Lakes, too.
In 2021, a study about the impact of acidification on freshwater bodies was carried out on Chinese mitten crabs in Taiwan. It was found that once the water acidity reaches the projected 2100 levels, the mortality rate of these crabs will increase three times.
Way Forward
According to the researchers, the damage has already been done. So the lakes would continue to acidify due to the carbon dioxide present in the atmosphere, along with the carbon-laden water runoffs from the land. Though the acidification cannot be totally eradicated, the damage can only be contained. Nothing much could be done to stop the acidification of the Great Lakes though, a collective global effort can be made to contain the damage. Without a collective global effort to reduce concentrated atmospheric carbon dioxide, not much can be done to check the decreasing pH level of the Great Lakes.
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