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Acidification of the seas: Graz-based chemists enhance precision of measuring probes

The acidification of the oceans, meaning a reduction of the pH level due to absorption of carbon dioxide from the atmosphere, comprises a serious threat to living organisms in the oceans. Nevertheless, up until now there have hardly been any effective and user-friendly methods and devices to precisely measure the change. A team at the Graz University of Technology developed a suitable measuring device. 

In addition to global warming, the increasing acidification of the oceans ranks among the primary consequences of the human emission of carbon dioxide. In water the gas is converted to acid, which affects, amongst others, calcareous shell-forming organisms. The growing acidification reduces their ability to form calcareous protective covers. In turn, due to the fact that they comprise the basis of the food chain, the threat to these organisms could seriously upset the marine ecosystem, marine researchers have been warning for a long time.

More measurements are necessary

In order to make better predictions, researchers require more measurements about the actual changes in acidity in the depths of the ocean. The commercial measuring devices which offer researchers a reliable data base to more precisely explore the acidification of the oceans are fare, expensive and imprecise, according to Ingo Klimant, Professor at the Institute for Analytical Chemistry at the Graz University of Technology. In order to achieve this goal, the American foundation Xprize, which has already awarded prizes for space projects, economical cars and gene mapping, has offered two prices of USD 1 million each for cheaper and better acidity sensors. The researchers in Graz were among 18 shortlisted from 77 entries, and were once again successful in the latest qualifying round, Klimant explained.

In recent days the performance of the submitted measuring devices was tested in a California laboratory with respect to measuring accuracy, stability and precision under controlled laboratory conditions. “We entered the competition with our device featuring optical-chemical sensors, and have reached the next round”, the researchers in Graz said. The sensors are based on a fluorescent indicator dye embedded into a polymer layer connected with an opto-electronic read-out unit with very low power consumption.  The fluorescence properties of the dye are influenced by the level of acidity of the water, in which case the pH value can be indirectly measured.

In February the devices of the winner will be subject to a one month endurance test, which will in turn determine whether the devices will be eligible to conclude the final tests at a depth of 3,000 meters starting in May 2015. The winner of the competition will be given a prize of USD 1 million.

Service: Information on the “Ocean Health Xprize” at and about the Graz University of Technology team at

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