#weathering — Public Fediverse posts on home.social

💧🌏 Greg Cocks @[email protected] · 2026-09-04 · 02:28 UTC

To Predict Tree Death, Scientists Tapped Gamma Rays To Peer Underground
(Airborne radiation sensors could help forecast and prevent drought-driven tree mortality_
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https://www.science.org/content/article/predict-tree-death-scientists-tapped-gamma-rays-peer-underground <-- shared technical article
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https://doi.org/10.1029/2026GL122182 <-- shared paper
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H/T @hannah Richter
“Over an 18-month period starting in 2023, the dense forests of Western Australia [WA] experienced a record-setting drought. Jarrah trees towering 35 metres high died off in patchy brown splotches, turning 400 square kilometres - 3% of the forest - into brittle, fire-prone stands. The event led researchers to wonder whether there was a better way to predict where such die-offs might occur both there and in other forests, a problem that has long been tricky to solve because important factors such as soil depth are hidden underground…
Now, those same researchers have unveiled a surprising new tool for predicting tree mortality: gamma rays [link above.] Resulting from the natural decay of the potassium-40 isotope from granite-rich bedrock, the radiation acts as a proxy for soil depth, which in turn signals how much water a tree can access during drought. The new method could be applied to other highly weathered soils, which cover one-third of Earth’s ice-free land...”
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"... PLAIN LANGUAGE SUMMARY: During a record-breaking drought and heat event in 2023–2024, forests in southwestern Australia experienced widespread, patchy die-off. While we know that extreme weather triggers these events, it is often a hidden factor, the thickness of soil and the depth to underlying bedrock, that determines which trees live or die. Trees growing in shallow soil over solid rock are highly vulnerable due to limited water storage. Here, [they] show how to map these hidden zones from the air using gamma rays that are naturally emitted by potassium in the ground. Like southwestern Australia, many parts of the world have highly weathered soils where potassium has been washed out of the upper layers of soil. However, [they] showed that higher potassium areas signal that potassium-rich bedrock is closer to the surface and this is sensitive for tens of meters. By comparing gamma ray maps with ground-based geophysical surveys and satellite data, [they] showed that these potassium hotspots accurately predict where forests are most likely to experience die-off during a drought. These types of soils cover about one-third of the Earth's land, so the method provides a powerful new tool for managers to identify and protect vulnerable forests from future, hotter droughts…”
#GIS #spatial #mapping #spatialanalysis #spatiotemporal #Australia #WesternAustralia #WA #forests #vegetation #bush #jarrah #karri #drought #heat #extremedrought #extremeweather #climatechange #water #waterresources #dieoff #soil #weathering #erosion #moisture #nutrients #airborne #gammarays #GRS #granite #gneiss #bedrock #geology #potassium40 #potassium #K #remotesensing #earthobservation #groundwater #interstitial #subsurface #waterstorage #electricalresistivitytomography

#gis #spatial #mapping #spatialanalysis #spatiotemporal #australia

💧🌏 Greg Cocks @[email protected] · 2026-06-23 · 04:43 UTC

Rock Weathering Can Counteract River CO2 Emissions Induced By Permafrost Thaw
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https://doi.org/10.1038/s41586-026-10664-8 <-- shared paper
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H/T @aaron Bufe
“[The researchers] measured carbon emissions and water chemistry in 50 headwater rivers draining 780,000 km² of the Tibetan Plateau.
The rivers flow in landscapes underlain by continuous permafrost and landscapes in which the permafrost has retreated since the last glacial maximum. They collect[ed] organic carbon from soils and dissolved inorganic carbon that is fixed by rock-weathering.
Where the permafrost cover is continuous, rivers emit CO2 from degrading (permafrost) soil carbon. Weathering reactions in these catchments are relatively slow.
In landscapes with (almost) no permafrost, carbon fluxes from weathering are faster than CO2 emissions from rivers.
Thus, as permafrost landscapes transition to landscapes without permafrost cover, chemical weathering reactions may play an ever more important role in riverine carbon cycling.
Interestingly, weathering can affect the carbon cycle in different ways. Where sulfide minerals are present, weathering reactions can emit CO2. Where silicate minerals dominate, weathering draws down CO2 from the atmosphere…”
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“Climate-induced permafrost thaw unlocks large stores of organic carbon that are mineralized and emitted as carbon dioxide (CO2) from rivers to the atmosphere. Concurrently, warming and permafrost thaw can increase mineral weathering rates, thus affecting the release and sequestration of inorganic carbon. Yet how these biological and geological carbon cycles interact and jointly affect CO2 dynamics (emission compared with drawdown) in permafrost rivers remains unknown. Here [they] combine[d] CO2 emissions, organic and inorganic solute concentrations, dual carbon isotopes (δ13C–Δ14C) and geochemical modelling to infer how permafrost thaw may affect river biogeochemistry over decades to centuries across the Qinghai–Tibet Plateau. Leveraging a gradient of thermal permafrost degradation, we find that river CO2 emissions decline, whereas solute fluxes from rock weathering increase with decreasing permafrost cover. Across this region, net CO2 drawdown fluxes from rock weathering are about 35% of river CO2 emissions, varying from around 15% in catchments with continuous permafrost to more than 100% in catchments with discontinuous or isolated permafrost. Thus, carbon fluxes from chemical weathering may become increasingly important with ongoing permafrost thaw, potentially even outpacing river CO2 emissions. [Their] findings disentangle the interplay between biological and geological carbon fluxes that are important for the cryosphere and the global carbon cycle…”
#permafrost #melting #thaw #climatechange #warming #Tibet #TibetanPlateau #Qinghai #water #hydrology #carbonemissions #CO2 #emissions #waterchemistry #waterquality #cryosphere #sediment #sedimentation #weathering #rock #carbon #river #riverine #carboncyling #geochemistry #biology #geology #soil