Editorial Assignment
Alaska’s Rusting Rivers
2023 for Scientific American
Tukpahlearick Creek, one of many rivers in remote north western Alaska, runs bright orange with iron and sulphuric acid. Scientists are trying to figure out why.
Dr. David Cooper a mountain wetland ecology and hydrology specialist digs a pit to determine among other things the proportions of peat to glade soil before hitting a layer of permafrost.
A basic metal probe used to measure the depth of permafrost. Permafrost is a thick layer of soil that remains frozen throughout the year.
Using a hand lens Dr. Roman Dial looks at Tomentypnum a species of moss. Moss are great indicators of pH levels because they are dependent on the surface soils.
Scientists begin to collect water samples and data at the seep, The straight lines visible in this seep are most likely game trails.
Fresh caribou tracks are found in the mud of the acid burn. While iron comes out of solution when exposed to oxygen at pH 7 and is an obvious mineral in orange deposits, copper and arsenic stay dissolved and are potentially very dangerous to human and animal populations.
pH testing papers show acidic waters (approximately pH 2-3) at the source of the acid burn on the mountain side. In rivers, lakes, and wetlands most species can’t survive if the water is too acidic - generally below 5.0.
Portrait of scientists (left to right) Timothy Lyons, Daniel Gregory, Christopher Tino, David Cooper, and Roman Dial on an outcrop of rocks with minor oxidized pyrite.
Melting snowpack over the iron rich stream.
Outcrop of rock scientists decide to take samples from as it sits just above an orange tributary of Timber Creek.
Daniel Gregory takes an up close look at a rock sample of the outcrop. He is looking for pyrite. It would explain the orange rivers - when pyrite breaks down it makes bisulfide and iron2+
The tools of a geologist: a notepad, a chisel, a bottle of 10% hydrochloric acid - if dropped on a rock full of carbonates the liquid will fizz, cloth rock sample bag, and a hammer. (Left to Right)
This acidic seep, rich with iron is hypothesized to be the newest scientist came across on this trip, because all of the vegetation around it is still alive. It was actively depositing minerals into the stream below.
Dr. David Cooper testing pH levels. Scientists also measure temperature, and electric conductivity or the total dissolved solids. Later in the lab they will determine the exact elemental composition.
Scientists walk the contours of the Baird Mountains in the western Brooks Range.
A crack in the ground indicates a slump of gravel or peat that is sliding towards the stream. This would occur as permafrost thaws.
A slow moving tributary of Tukpahlearick River with excessive iron deposits.
Tino, Lyons and Cooper inspect the longest burn we come across on this trip; it runs approximately 2km all the way down the hillside into Tukpahlearick Creek.
Image of dead vegetation found in the burn or “kill zone”.
Image of iron seep coming from the ground below and dead vegetation in the "burn" or “kill zone”. This burn runs approximately 2km all the way down the hillside into Tukpahlearick Creek.
Roman Dial inspects the length of the acid burn.
White precipitate is possibly sulfate within the seep.
Timothy Lyons and Daniel Gregory survey the landscape towards the large acid burn.
Basecamp on the bush plane landing strip.