Geology topics

Josie Arcuri

Publications and source records attributed to Josie Arcuri.

2 recordsLinked to original sources

USGS2026

Erosional and hydrological controls on the age and thermochemical stability of particulate organic carbon in an Arctic river

Understanding the mechanisms that drive the mobilization and fate of organic carbon (OC) in Arctic landscapes is important for modeling the feedbacks among permafrost thaw, carbon cycling, and climate change. While significant progress has been made toward measuring in situ OC decomposition in permafrost soils and bulk particulate organic carbon (POC) export from Arctic rivers, few studies have distinguished the source and lability of POC across Arctic landscapes, limiting our ability to predict whether mobilized POC will be oxidized to CO 2 and CH 4 or buried in downstream depositional environments. This study uses ramped pyrolysis/oxidation radiocarbon (RPO- 14 C) analyses to investigate spatial and temporal variations in the thermochemical stability and radiocarbon content of fluvial POC during downstream transport from mountains to the coast in the Canning River (North Slope, Alaska). Fluvial POC in the headwaters is predominantly comprised of high activation energy, thermally recalcitrant petrogenic OC (OC petro ) derived from shale bedrock. Moving into the foothills and low-relief coastal plains, river bank erosion primarily drives mobilization of labile, low activation energy, soil-derived OC (OC soil ). Fluvial POC in mountainous upstream reaches consisted of ∼70% OC petro and just ∼30% OC soil , while POC in the downstream coastal plain reaches comprised ∼85% OC soil and ∼15% OC petro . The high relative lability of POC exported to the coast indicates high susceptibility to oxidation and microbial decomposition, which could enhance CO 2 release as the Arctic hydrologic cycle intensifies. However, the persistence of refractory OC petro in the suspended load indicates the potential for long-term burial of rock organic carbon in marine sediments.

Alaska↗

USGS2024

Impacts of convective storms on runoff, erosion, and carbon export in a continuous permafrost landscape

Permafrost holds more than twice the amount of carbon currently in the atmosphere, but this large carbon reservoir is vulnerable to thaw and erosion under a rapidly changing Arctic climate. Convective storms are becoming increasingly common during Arctic summers and can amplify runoff and erosion. These extreme events, in concert with active layer deepening, may accelerate carbon loss from the Arctic landscape. However, we lack measurements of carbon fluxes during these events. Rivers are sensitive to physical, chemical, and hydrological perturbations, and thus are excellent systems for studying landscape responses to thunderstorms. We present observations from the Canning River, Alaska, which drains the northern Brooks Range and flows across a continuous permafrost landscape to the Beaufort Sea. During summer 2022 and 2023 field campaigns, we opportunistically monitored river discharge, sediment, and organic carbon fluxes during several thunderstorms. During one notable storm, river discharge nearly doubled from ~130 m3/s to ~240 m3/s, suspended sediment flux increased 70-fold, and the particulate organic carbon (POC) flux increased 90-fold relative to non-storm conditions. Taken together, the river exported ~16 metric tons of POC over one hour of this sustained event, not including the additional flux of woody debris. Furthermore, the dissolved organic carbon (DOC) flux nearly doubled. Although these thunderstorm-driven fluxes are short-lived (hours to days), they play an outsized role in exporting organic carbon from Arctic rivers. Understanding how these extreme events impact river water, sediment, and carbon dynamics will help predict how Arctic climate change will modify the global carbon cycle.

Alaska↗