3 April 2024

Drainage channels in peatlands produce significant emissions

In Southeast Asian peatlands, man-made channels to drain soil contribute to carbon leakage into the atmosphere, research says

by Matteo Cavallito

 

Drainage channels in peatlands in Southeast Asia are an underestimated source of greenhouse gas emissions. This is reported in a study conducted by the Scripps Institution of Oceanography at the University of California San Diego. The investigation, conducted with the help of American researchers from Stanford University and Indonesian scientists from Tanjungpura University, targets human activities conducted in these peculiar environments, which are known to be important carbon sinks.

Degradation of peatlands is responsible for 5% of anthropogenic emissions

The study, published in the journal Nature Geoscience, recalls how peatlands, despite covering just 3 percent of the Earth’s surface, store twice as much carbon as all the world’s forests. Decisive in these ecosystems is stagnant water that prevents dead plants from fully decomposing by limiting their exposure to oxygen. Provided, of course, that there is no outside intervention.

“In Southeast Asia, people have drained and deforested around 60 million acres of peatlands over the past three decades, largely for palm oil and timber harvest,” explains a statement from the California university, “leaving only 6% untouched.”

Peatlands, in other words, are damaged and dead plant material is exposed to oxygen. The resulting completion of decomposition generates the release of CO2. “Globally, degraded peatlands alone account for around 5% of human-caused greenhouse gas emissions annually,” the authors explain.

The study

The impact of peatland degradation on climate has long been a focus of interest for many researchers. What is unique about this study, the authors recall, is its focus on what happens to carbon that flows through drainage channels before reaching rivers or the ocean. To better understand the phenomenon, the scientists collected water samples from peatland channels in West Kalimantan province, Indonesia subsequently performing some experiments in the laboratory.

In detail, the authors measured how quickly the microbes were able to break down organic matter and the amount of CO2 produced in the process. Noting how certain conditions-sunnier days, higher concentrations of oxygen in the water-could generate higher rates of emission.

35 percent of carbon leaks out before reaching the ocean

“Based on the results of the experiments, the team estimated that each square meter of peatland canal area in the region releases an average of roughly 70 milligrams of carbon dioxide per day,” the statement notes. In addition, “breakdown by sunlight and microbes may send around 35% of the peat carbon that dissolves into the drainage canals into the atmosphere as carbon dioxide.”

According to the authors, in short, we would be facing a significant source of emissions, the impact of which would still be overlooked. Release from the canals, in fact, reduces the amount of the element capable of reaching the oceans. And, with it, the overall ability of marine environments to offset the impact of peatland degradation by collecting and storing carbon and thus limiting its atmospheric concentration.