pH

pH is a measure of the acidity or basicity of a solution, ranging from 0 to 14. A pH of 7 is considered neutral, while a pH below 7 is acidic and a pH above 7 is basic. In our oceans, pH plays a critical role in determining the health and stability of marine ecosystems. (R22)

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The ocean's pH is primarily affected by the absorption of carbon dioxide (CO2) from the atmosphere, which reacts with seawater to form carbonic acid. This process, known as ocean acidification, leads to a decrease in pH, making the ocean more acidic. (R22)

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Ocean acidification is a growing concern as human activities continue to increase the amount of carbon dioxide in the atmosphere. Therefore, it's essential to monitor pH levels in our oceans and take steps to reduce carbon emissions. (R18)

Since the beginning of the Industrial Revolution, the pH of surface seawater has decreased by approximately 0.1 units, which might seem small but represents a 30% increase in acidity. Some areas of the ocean are experiencing even greater declines in pH, such as the Arctic and Southern Oceans. (R18)

The change in pH levels has resulted in numerous impacts on marine ecosystems. Some of the most critical ones are listed below:

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Loss of biodiversity

• The decline in pH levels due to ocean acidification can lead to biodiversity loss in marine ecosystems, as some species are more vulnerable to the effects of increased acidity than others. This can have significant implications for the functioning and productivity of marine ecosystems. (R23)

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Changes in marine food webs

• Ocean acidification can alter the availability of nutrients and affect the growth and survival of phytoplankton, which form the basis of the oceanic food chain. This can have indirect effects on marine food webs, leading to changes in the distribution and abundance of marine species. (R20)

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Impacts on marine organisms 

• Ocean acidification can affect the growth, development, and survival of many marine organisms, particularly those with shells or skeletons made of calcium carbonate, such as corals, molluscs, and some types of plankton. Increased acidity can dissolve their structures, making it more difficult for

      these organisms to survive and reproduce. (R18)

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Economic impacts

• Ocean acidification can also have economic impacts, particularly on industries that rely on marine resources, such as fisheries and tourism. The decline in fish populations and the degradation of coral reefs can have significant economic consequences for these industries and the communities that depend on them. (R23)

 

Sam Dupont gave us a deeper insight about pH and ocean acidification during his interview. He explained that if we continue to release CO2 like we do now, it is projected that the overall pH will decrease by 0.3-0.4 (0.4 is a doubling of the number of protons, since the scale is logarithmic). Dupont also stresses that the emission of carbon dioxide has a profound impact on the ocean's chemistry beyond altering its pH level. As a significant proportion of carbon dioxide released is absorbed by the oceans, it affects not only acidity but also the levels of carbonate and bicarbonate, as well as carbon levels. These changes are likely to lead to a reduction in biodiversity and the services provided by the ocean. Sam cites the US oyster industry as an instance of this, which suffered substantial losses due to acidification.

 

During the interview, Dupont emphasized the current need for sensor technology. He highlighted that combining sensors with citizen science would facilitate scientists, and collecting comprehensive data would be highly advantageous. The sensor's value lies in its ability to measure pH, a critical parameter in understanding ocean acidification. By collecting pH data, researchers gain insights into the changing acidity levels and can effectively monitor the impact of carbon dioxide absorption. This data empowers researchers to create maps, provide recommendations, and track progress in mitigating acidification. pH data is essential for making informed decisions and safeguarding marine ecosystems.

 

The pH level data gap

• As earlier presented, ocean acidification is a significant environmental issue that can have a range of impacts on marine ecosystems, including the growth and survival of marine organisms and the overall health of ocean ecosystems. To understand the effects of ocean acidification, it is important to measure the pH of seawater over time and across different locations. 

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However, there are many ocean areas where pH data is currently lacking, particularly in remote or hard-to-reach regions. This makes it challenging to understand the extent and impact of ocean acidification on a global scale. There is also a data gap between deep water and the water's surface. The majority of pH measurements in the ocean are taken near the surface, as this is where most research vessels and instruments operate. However, pH levels can vary significantly between the surface and deeper waters, and understanding these variations is essential for understanding the overall health of ocean ecosystems. Deep ocean pH data is more difficult to collect, as it requires specialized equipment and techniques to measure pH at dept. However, there is still a significant gap in our understanding of pH variations in the deep ocean, and more research is needed to fully understand the impacts of ocean acidification on deep-sea ecosystems. (R18)