Some birds are canaries in the coal mine, telling us that something’s gone wrong long before we notice it.  Harlequin ducks (Histrionicus histrionicus) are performing that service in Alaska.

A 2017 study by the Biodiversity Research Institute looked for mercury in Alaska’s coastal waters by testing blood samples and molted feathers from harlequin ducks at Kodiak and Unalaska Islands. Blood samples were used because they indicate recently consumed mercury. Molted feathers show mercury when the feathers were formed a year before. 

The study found mercury in harlequins from both locations but those at Unalaska, midway in the Aleutian chain, had eight times more than those at Kodiak, nestled in the Gulf of Alaska. The study then tested the ducks’ main food at Unalaska — blue mussels — and found it there, too.

This is important news for Aleutian residents because they eat lots of seafood.  It also matters to the rest of us since Unalaska’s main port, Dutch Harbor, is the largest fisheries port in the U.S. by volume caught.  

Mercury apparently increases westward in the Aleutian chain. A 2014 study found mercury in fish above the human consumption limit at the western island of Agattu.

Where is the mercury coming from?  In the continental U.S. airborne mercury comes from coal-fired power plants and is regulated and reduced by the EPA.  It can also come from active volcanoes, obviously out of our control.

At this point scientists don’t know where the mercury is coming from, but China’s coal-fired industries are a good bet.  The prevailing wind in the Aleutian Islands originates in Asia more than six months of the year.

Unfortunately Alaskans can’t prevent mercury pollution that reaches them from Asia.  Meanwhile the harlequins warn of danger.

(photo of harlequin duck from Wikimedia Commons, screenshot of global winds from earth visualization website; click on the caption links to see the originals)

The Youghiogheny River is famous for whitewater rafting near Ohiopyle but there’s a tributary downstream where white water is bad.

On the GAP Trail north of Buena Vista — near marker 121 — you can hear a rushing waterfall before you see it.  When you reach its location it’s not a pretty sight. The waterfall stains everything white.

Early this month I looked at the water and its outflow in the Youghiogheny River and discovered that the water is clear and colorless, though it leaves a white residue on everything it touches.

Here are some closer looks.

The water is clear because it’s acidic. The residue is from abandoned mine drainage (AMD), a problem that pollutes more than 2,500 miles of Pennsylvania rivers and streams.

Most AMD in western Pennsylvania is orange like this outfall into Chartiers Creek at Wingfield Pines Conservation Area. The rust color comes from dissolved iron.

The white waterfall is caused by dissolved aluminum sulfate from an old coal mine in the hill above the waterfall. 

As water from the abandoned mine travels downhill it blends with clean water that raises the pH (i.e. lowers the acidity). At some point the diluted mine water isn’t acidic enough to dissolve aluminum sulfate so the aluminum precipitates out as white residue.

This color is somewhat unusual but there are other white streams in Allegheny County including Milk Run in North Fayette Township along Mahoney Road.  This year the Allegheny County Conservation District is reclaiming Milk Run at the cost of nearly a million dollars.

I can’t imagine the price tag for fixing the White Waterfall.

(photo credits: waterfall by Kate St. John. Aluminum sulfate crystals from Wikimedia Commons; click on the caption to see the original)