Hillsides collapsing into Arctic streams can trigger CO2 release to the atmosphere

Permafrost thaw slumps draining into a river on the Peel Plateau in western Canada

Featured Image: Permafrost thaw slumps draining into a river on the Peel Plateau in western Canada. Photo courtesy Scott Zolkos, lead author of the paper.

Paper: Experimental Evidence That Permafrost Thaw History and Mineral Composition Shape Abiotic Carbon Cycling in Thermokarst-Affected Stream Networks

Authors: Zolkos, Scott & Suzanne E. Tank.

The rivers and streams of the Arctic transfer atmospheric heat into the surrounding permafrost (perennially frozen) soil. At the same time, surface soils up to 1 meter deep undergo annual freeze-thaw cycles. When warmer air arrives in the summer months, the combination of warming air and river water can thaw large chunks of ice-rich permafrost soil along the stream’s edge. Thawed permafrost breaks away from the surrounding hillsides and causes catastrophic slope failures, transporting huge amounts of sediment into the nearby waterways. As the stream water becomes murky it takes on the appearance of chocolate milk, and simultaneously, the geochemistry of the water changes.

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Where the river flows: India’s catchment crisis

Dandeli river, Karnataka, India

Paper: Insights into riverscape dynamics with hydrological, ecological and social dimensions for water sustenance

Authors: T.V. Ramachandra, S. Vinay, S. Bharath, M.D.Subash Chandran, and Bharath H.Aithal

A catchment or watershed represents an intricate network of streams that coalesce into a river. In ecology, river networks are considered as ecosystems since they facilitate interactions between organisms and their environments. A healthy river ecosystem sustains the biodiversity of fringing forests and aquatic habitats, and enhances the landscape’s resilience to water resource development, droughts and climate change. Rivers provide water for domestic, agricultural and industrial use, and sustain native vegetation which in turn regulates the water cycle, and provides forest-based goods and services.

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Evidence of pollution all the way to the poles

Featured Image: Lake Hazen in front of the Grant Land Mountains – photo courtesy Kyra St. Pierre, a co-author of the Sun et al. paper.

Paper: Glacial melt inputs of organophosphate ester flame retardants to the largest High Arctic lake

Authors: Sun, Yuxin, Amilia O. De Silva, Kyra A. St Pierre, Derek C. G. Muir, Christine Spencer, Igor Lehnherr, John J. MacInnis

Far from human habitation Lake Hazen sits north of the Arctic Circle surrounded by pristine, treeless mountains. But even there, the telltale chemical fingerprints of human pollution can be found.

Spring and summer in the far North are a short three-month period of reawakening, glacial melt, and permafrost thaw. During these months, meltwater transports anything that has collected on top of glaciers, like particles, nutrients, and contaminants deposited from the atmosphere, flowing down rivers and into glacial lakes. 

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Rivers of Memory: India

Paper: Evolution of modern river systems: an assessment of ‘landscape memory’ in Indian river systems

Authors: Vikrant Jain, Sonam, Ajit Singh, Rajiv Sinha, S. K. Tandon

“A river cuts through rock not because of its power, but because of its persistence.”

James N Watkins

In geomorphology, the persistence of rivers is etched into the very landscape – a memory of the forces that once shaped it, and continue to do so, slowly, and inexorably. Landscape memory, as Gary John Brierley once wrote, is the imprint of the past upon contemporary landscapes, which include geologic, climatic, and anthropogenic factors.

The rivers of the Indian subcontinent bear witness to forces that shaped them over millennia – and a recent publication in the Journal of International Geosciences traces the evolution of India’s river systems at different time scales.

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