14 DAY TRIAL // A group of scientists has recently determined that the salty chemistry of the Dead Sea is causing interesting effects in the air masses above it. Large amounts of oxidized mercury were discovered to permeate the air, a chemical that is usually encountered in polar regions.
Experts conducted the new investigation took sporadic measurements of the air quality above the large lake, and identified several periods of extremely high atmospheric oxidized mercury, that they could not explain at first.
The work was led by research scientist Daniel Obrist, with funds provided by the US National Science Foundation (NSF). Investigators from the Desert Research Institute in Reno, Nevada, and at Hebrew University in Israel were also members of the team.
One of the most negative things about oxidized mercury is that it can easily deposit itself in the environment above which it's formed, leading to its contamination. Mercury exists in the atmosphere n either a pure or oxidized state.
Human and natural processes alike release the chemicals, the researchers write in the paper detailing the findings, which appears in the November 28 online issue of the top journal Nature Geoscience.
Global ecosystems are under constant threat from mercury contamination, given that the chemical can act as a very potent neurotoxin for complex living organisms. Food chains tend to accumulate the chemical in high amunts.
“These levels are of major concern to humans, especially in the consumption of mercury-laden fish,” Obrist explains. The main source of exposure the US population has to mercury, for example, is fish consumption.
This far, dangerously-high levels of oxidized mercury have only been discovered above polar regions, where it is formed during atmospheric mercury depletion events (AMDE). Concentrations can reach harmful levels very easily at those lcoations.
In the new study, “we've found near-complete depletion of elemental mercury – and formation of some of the highest oxidized mercury levels ever seen – above the Dead Sea, a place where temperatures reach 45 degrees Celsius,” the team leader says.
Until now, chemists and atmospheric scientists believed that high temperatures prevented this sort of chemical reactions from taking place.
“Elemental mercury is somewhat resistant to oxidation, so it's been difficult to explain levels of oxidized mercury measured in the atmosphere outside polar regions,” says expert Alex Pszenny.
“These new results provide an explanation,” adds the official, who is the director of the NSF Atmospheric Chemistry Program.