Green and poisonous
Algae are blooming in Ohio's Lake Erie, polluting the drinking water of around 500,000 people. What is it that makes these green organisms grow so fast - and how dangerous are they for humans?
Turquoise-blue or poisonous-green?
As you can see, it's the latter! A large slick of algae is covering Lake Erie in the U.S. State of Ohio. Researchers had already warned that such algae-growth was likely to occur more often back in 2011. The build-up has polluted this supply of drinking water for nearby cities. Even boiling the water does not help. On the contrary, this increases the toxin-levels.
Misleading name
Technically speaking, this green slime is not algae but rather a form of bacteria. More precisely: cyanobacteria. In the past, these were classified as "blue-green-algae", partly because they multiply using photosynthesis like algae. There are thousands of kinds of cyanobacteria, but only about 40 of them actually produce toxins.
Trust your nose
People can catch a whiff of the sulfurous odor from far away. Fortunately it is repugnant enough to repel most swimmers. This specific genus of cyanobacteria, called Microcystis, can cause skin irritations, inflammation and allergic reactions if it comes into contact with the skin, eyes or mouth. It's more dangerous if swallowed or imbibed. Then it can trigger diarrhea or respiratory diseases.
Swift spread in summer
Agricultural fertilizer helps fuel the growth in summer, scientists say. Storms and rains wash these chemicals with high nitrogen and phosphate concentrations of the fields and into the rivers and lakes. When the water-temperature rises above 16 degrees Celsius (about 60 Fahrenheit) and the water does not circulate, the bacteria feel right at home - and multiply rapidly.
A rare, essential commodity
In Ohio the National Guard is helping supply the people with drinking water. Bottled water supplies have almost sold out everywhere within 80 kilometres (about 25 miles) around Toledo. According to the latest meassurements, the Microcystin-levels in Lake Erie are going down, but further tests are necessary so as to eliminate any risks, Mayor Michael Collins said.
Waiting it out
Three is currently no proven method to fight the green-blue bacteria, other than waiting forthe elements to help. What's somewhat reassuring is that after sunset, or when clouds cover the sun and when the temperatures drop, the concentration will start receding.