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1. Geochemical phosphorus sequestration in tundra soils limits primary production in Arctic headwater streams and rivers. Upper Kuparuk River, North Slope, Alaska, 2020-2023.

   https://doi.org/10.18739/A2348GJ1Z  

   Sutor, Frederick (January 2024, NSF Arctic Data Center)

   Climate warming in the Arctic region is thawing previously frozen soil (permafrost). Permafrost thaw alters landscape hydrology, increases weathering rates, and thus increases the delivery of solutes to adjacent waters. Long-term monitoring of the Kuparuk River (North Slope, Alaska) confirms significant increases in many solutes that are indicative of thawing permafrost. However, there is no evidence of an increase in phosphorus (P), the nutrient that most often limits primary production in tundra streams. Here, we show that soils in the upper Kuparuk River watershed have a high biogeochemical sorption capacity that can limit P mobility and use published data to show that this may be a pan-Arctic characteristic. While P bioavailability is restricted by vegetative cycling, we found that concentrations of Mehlich-3 extractable iron (Fe) and aluminum (Al) also impart a very high P geochemical sorption capacity across our study sites. Analysis of a pan-Arctic soils database suggests that this high P sorption capacity could be a ubiquitous feature of Arctic soils. Therefore, we conclude that while warming-induced permafrost thaw may increase P mobility, simultaneous increases in pedogenic secondary Fe/Al minerals will continue to retain P in tundra soils and limit biological productivity in adjacent aquatic systems. 

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2. Geochemical Phosphorus Sequestration in Tundra Soils Impedes Delivery of Bioavailable Phosphorus to the Kuparuk River, Alaska, USA: Implications for the Broader Arctic Region

   https://doi.org/10.1029/2025JG008803  

   Sutor, Frederick W; Roy, Eric D; Schroth, Andrew W; Michaud, Alexander B; Emerson, David; Herndon, Elizabeth M; Kinsman‐Costello, Lauren; Hurley, Stephanie E; Bowden, William B (October 2025, Journal of Geophysical Research: Biogeosciences)

   Abstract Long‐term river monitoring of the Kuparuk River (North Slope, Alaska, USA) confirms significant increases in solutes that are indicative of active layer thickening due to thawing permafrost. However, there is no evidence of an increase in total dissolved phosphorus (TDP) or soluble reactive phosphorus (SRP), the nutrient that limits primary production in this and similar rivers in the region. Here, we show that Mehlich‐3 extractable iron (Fe) and aluminum (Al) in active layer soils impart high P geochemical sorption capacities across a range of landscape features that we would expect to promote lateral movement of water and solutes to headwater streams in our study watershed. Reanalysis of a recently published pan‐Arctic soils database that includes active layer and permafrost soil samples suggests that this high P sorption capacity could be common in other parts of the Arctic region. We conclude that soil minerals enhance P retention on hillslopes and propose pedogenic secondary Fe and Al minerals may continue to retain P in these soils and limit biological productivity in the adjacent river even as active layer thickening increases potential P mobility in the watershed. We suggest that similar interactions may occur in other areas of the Arctic where comparable geochemical conditions prevail. 

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3. Tracing Seasonal Ground Thaw with Stream Chemistry in Alaskan Arctic Permafrost Catchments

   https://doi.org/10.1002/hyp.70512  

   Grose, Amelia L; Zarnetske, Jay P; Grewal, Arsh; Shogren, Arial J; Rec, Abigail F; O'Donnell, Jonathan A; Abbott, Benjamin W; Bowden, William B (April 2026, Hydrological Processes)

   ABSTRACT In permafrost regions, hydrological and biogeochemical processes are substantially influenced by ground thaw dynamics. However, seasonal and interannual changes in ground thaw are difficult to measure at catchment and regional scales. Prior studies have used stream chemistry to indicate water flowpaths at catchment scales by taking advantage of vertical differences in solute sources, but the consistency of these chemical tracers across varying Arctic landscapes is poorly understood. In this study, we analysed nine potential thaw depth tracers (Ba, Ca, Fe, K, Mg, Na, S, Si and Sr) for three consecutive thaw seasons (June through early September, 2021–2023) across three catchments with different landscape characteristics in the continuous permafrost region of northern Alaska, United States. We used generalised additive models to test which solutes made effective tracers of thaw depth across catchments, based on significant concentration–discharge relationships and seasonality. Five solutes met the criteria for an effective thaw tracer in at least one catchment, but there was no single tracer that worked across all three catchments, with the differences likely due to variation in catchment characteristics (e.g., geology, soils, lake coverage). Tracking ground thaw dynamics via stream chemistry is a promising approach that complements modelling and point measurements of thaw by filling gaps in spatial and temporal scales. Overcoming the current limitations of observing ground thaw across spatial scales, seasons and years is needed as thaw dynamics will become increasingly important in Arctic systems experiencing both warming and hydrologic intensification. 

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4. Rapid Saline Permafrost Thaw Below a Shallow Thermokarst Lake in Arctic Alaska

   https://doi.org/10.1029/2023GL105552  

   Jones, Benjamin M.; Kanevskiy, Mikhail Z.; Parsekian, Andrew D.; Bergstedt, Helena; Ward Jones, Melissa K.; Rangel, Rodrigo C.; Hinkel, Kenneth M.; Shur, Yuri (November 2023, Geophysical Research Letters)

   Permafrost warming and degradation is well documented across the Arctic. However, observation‐ and model‐based studies typically consider thaw to occur at 0°C, neglecting the widespread occurrence of saline permafrost in coastal plain regions. In this study, we document rapid saline permafrost thaw below a shallow arctic lake. Over the 15‐year period, the lakebed subsided by 0.6 m as ice‐rich, saline permafrost thawed. Repeat transient electromagnetic measurements show that near‐surface bulk sediment electrical conductivity increased by 198% between 2016 and 2022. Analysis of wintertime Synthetic Aperture Radar satellite imagery indicates a transition from a bedfast to a floating ice lake with brackish water due to saline permafrost thaw. The regime shift likely contributed to the 65% increase in thermokarst lake lateral expansion rates. Our results indicate that thawing saline permafrost may be contributing to an increase in landscape change rates in the Arctic faster than anticipated. 

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5. Anoxic conditions maintained high phosphorus sorption in humid tropical forest soils

   https://doi.org/10.5194/bg-17-89-2020  

   Lin, Yang; Gross, Avner; O'Connell, Christine S.; Silver, Whendee L. (January 2020, Biogeosciences)

   null (Ed.)

   Abstract. The strong phosphorus (P) sorption capacity of iron (Fe)and aluminum (Al) minerals in highly weathered, acidic soils of humidtropical forests is generally assumed to be an important driver of Plimitation to plants and microbial activity in these ecosystems. Humidtropical forest soils often experience fluctuating redox conditions thatreduce Fe and raise pH. It is commonly thought that Fe reduction generallydecreases the capacity and strength of P sorption. Here we examined theeffects of 14 d oxic and anoxic incubations on soil P sorption dynamics inhumid tropical forest soils from Puerto Rico. Contrary to the conventionalbelief, soil P sorption capacity did not decrease under anoxic conditions,suggesting that soil minerals remain strong P sinks even under reducingconditions. Sorption of P occurred very rapidly in these soils, with atleast 60 % of the added P disappearing from the solution within 6 h.Estimated P sorption capacities were much higher, often by an order ofmagnitude, than the soil total P contents. However, the strength of Psorption under reducing conditions was weaker, as indicated by the increasedsolubility of sorbed P in NaHCO3 solution. Our results show that highlyweathered soil minerals can retain P even under anoxic conditions, where itmight otherwise be susceptible to leaching. Anoxic events can alsopotentially increase P bioavailability by decreasing the strength, ratherthan the capacity, of P sorption. These results improve our understanding ofthe redox effects on biogeochemical cycling in tropical forests. 

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