In 2007, the Department of Water Protection in Los Angeles detected high levels of bromate in the Ivanhoe reservoir. Bromate forms when sunlight causes chlorine to oxidise bromide. Bromide is a natural constituent in water, particularly groundwater, while chlorine is generally added to water supplies to kill any bacteria, viruses and protozoa.
The reservoir facility, which is 102 years old, supplies more than 600,000 people with potable water in downtown and South LA. When the Department of Water Protection realised the problem with bromate, they began construction of a new underground reservoir, but while the new facility was being built they had to determine a way to keep the sunlight out of the water.
The method had to be quick and cost effective. The solution was “bird balls” which are made of polyethylene and cost only 40 cents each. 400,000 balls were dropped into the reservoir on June 2008, where they were to remain for the next four to five years until the new underground reservoir is completed.
A fun Friday video. The city of Los Angeles has a chemistry problem. There are high amounts of bromine in several reservoirs that supply the city with water and when bromide and chloride (salt) ions react with sunlight, they form bromate, a carcinogen to humans. The city’s solution? Spending tens of millions of dollars on plastic balls that block sunlight out of the reservoirs. They also cut down on evaporation, saving hundreds of millions of gallons of water per year. Here’s a gigantic truck filled with plastic balls being dumped into a reservoir near L.A..
Some chemical reactions don’t go straight from reactants to products: They oscillate back and forth for a time before reaching a conclusion. One of these—the Belousov-Zhabotinsky reaction—is shown here at high speed (eight times faster than reality). The circular regions of the solution in this petri dish tip back and forth between being rich in bromate ions or in bromide ions. Although the reaction’s inner workings aren’t perfectly understood, the color changes arise from an indicator called ferroin, which turns blue when oxidized and red when reduced by bromine ions in their different oxidation states. After about 30 minutes, this reaction eventually dies down, the solution settling into a dull, blue color.
Photo by @GerdLudwig. The surface of the large open-air Ivanhoe Reservoir in Los Angeles is completely covered with over three million black plastic balls, which help deflect UV rays. In 2007, high levels of bromate - a carcinogen formed when bromide and chlorine react with sunlight - were found in its water which prompted officials to look for affordable ways of shading the reservoir. A biologist suggested so-called “bird-balls”, commonly used by airports to prevent birds from congregating in wet areas alongside runways. The balls, which cost 40 cents each, are made of polyethylene, with carbon coating.
The city recently continued with the program, covering the LA Reservoir as well.
@thephotosociety @natgeocreative @theimagereview #Ivanhoe #reservoir #LosAngeles #California #preservation #chemicals #boat #carcinogen #environment #bromate by natgeo