Seasonal export of carbon, nitrogen, and major solutes from Alaskan catchments with discontinuous permafrost

Petrone, Kevin C.; Jones, Jeremy B.; Hinzman, L. D.; Boone, Richard D.

doi:10.1029/2005jg000055

Cited by 160 publications

(259 citation statements)

References 62 publications

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“…CPCRW is located in the Yukon-Tanana Uplands northeast of Fairbanks, AK, a part of the boreal forest that has seen strong increases in air temperature and forest browning (Ju and Masek, 2016) over several decades. Annual average air temperature is −2.5 • C, and annual average precipitation 400 mm (Petrone et al, 2006). The watershed's lowlands and north-facing slopes are dominated by black spruce (Picea mariana (Mill.)…”

Section: Field Samplingmentioning

confidence: 99%

“…Laboratory experiments offer precise control but lack the in situ nature of field manipulations (Sistla et al, 2013), raising uncertainties as to what degree their results can be extrapolated. Soils isolated during incubation may, for example, underestimate temperature sensitivity of respiration (Podrebarac et al, 2016) or exhibit lag effects . It should also be noted that our 100-day incubation was not long enough to observe slowly cycling soil fractions, which may vary in their response to experimental manipulation (Karhu et al, 2010).…”

Section: Limitations and Weaknessesmentioning

confidence: 99%

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Temperature and moisture effects on greenhouse gas emissions from deep active-layer boreal soils

2016

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Abstract. Rapid climatic changes, rising air temperatures, and increased fires are expected to drive permafrost degradation and alter soil carbon (C) cycling in many high-latitude ecosystems. How these soils will respond to changes in their temperature, moisture, and overlying vegetation is uncertain but critical to understand given the large soil C stocks in these regions. We used a laboratory experiment to examine how temperature and moisture control CO 2 and CH 4 emissions from mineral soils sampled from the bottom of the annual active layer, i.e., directly above permafrost, in an Alaskan boreal forest. Gas emissions from 30 cores, subjected to two temperatures and either field moisture conditions or experimental drought, were tracked over a 100-day incubation; we also measured a variety of physical and chemical characteristics of the cores. Gravimetric water content was 0.31 ± 0.12 (unitless) at the beginning of the incubation; cores at field moisture were unchanged at the end, but drought cores had declined to 0.06 ± 0.04. Daily CO 2 fluxes were positively correlated with incubation chamber temperature, core water content, and percent soil nitrogen. They also had a temperature sensitivity (Q 10 ) of 1.3 and 1.9 for the field moisture and drought treatments, respectively. Daily CH 4 emissions were most strongly correlated with percent nitrogen, but neither temperature nor water content was a significant first-order predictor of CH 4 fluxes. The cumulative production of C from CO 2 was over 6 orders of magnitude higher than that from CH 4 ; cumulative CO 2 was correlated with incubation temperature and moisture treatment, with drought cores producing 52-73 % lower C. Cumulative CH 4 production was unaffected by any treatment. These results suggest that deep active-layer soils may be sensitive to changes in soil moisture under aerobic conditions, a critical factor as discontinuous permafrost thaws in interior Alaska. Deep but unfrozen high-latitude soils have been shown to be strongly affected by long-term experimental warming, and these results provide insight into their future dynamics and feedback potential with future climate change.

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Section: Field Samplingmentioning

confidence: 99%

Section: Limitations and Weaknessesmentioning

confidence: 99%

Temperature and moisture effects on greenhouse gas emissions from deep active-layer boreal soils

2016

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“…Carey (2003) found that the spring freshet contributes to more than 50 % of the DOC export as well as to the spring snowmelt contribution of DOC (69 %) in the high-permafrost area of the Yukon Territory, Canada. Also, in Alaskan permafrost areas, the spring freshet was found to account for 51 % of the annual 532 R. Giesler et al: Catchment-scale dissolved carbon concentrations and export estimates DOC export in a high-permafrost watershed, while it was otherwise less than 20 % of the annual DOC flux in lowpermafrost watersheds (Petrone et al, 2006;MacLean et al, 1999). The increase in stream water DOC concentrations from baseflow to the snowmelt peak further differed between high-permafrost and low-permafrost catchments, with the increase being 12-fold in the former compared to 6-fold in the latter (Petrone et al, 2006).…”

Section: Seasonal Patterns In Stream Water Doc and Dicmentioning

confidence: 99%

“…Also, in Alaskan permafrost areas, the spring freshet was found to account for 51 % of the annual 532 R. Giesler et al: Catchment-scale dissolved carbon concentrations and export estimates DOC export in a high-permafrost watershed, while it was otherwise less than 20 % of the annual DOC flux in lowpermafrost watersheds (Petrone et al, 2006;MacLean et al, 1999). The increase in stream water DOC concentrations from baseflow to the snowmelt peak further differed between high-permafrost and low-permafrost catchments, with the increase being 12-fold in the former compared to 6-fold in the latter (Petrone et al, 2006). Carey (2003) suggested that permafrost dominated hillslopes potentially have a larger DOC reservoir and that permafrost dominated hillslopes are more effective at delivering DOC to the stream due to increased lateral flow.…”

Section: Seasonal Patterns In Stream Water Doc and Dicmentioning

confidence: 99%

Catchment-scale dissolved carbon concentrations and export estimates across six subarctic streams in northern Sweden

et al. 2014

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Abstract. Climatic change is currently enhancing permafrost thawing and the flow of water through the landscape in subarctic and arctic catchments, with major consequences for the carbon export to aquatic ecosystems. We studied stream water carbon export in several tundra-dominated catchments in northern Sweden. There were clear seasonal differences in both dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) concentrations. The highest DOC concentrations occurred during the spring freshet while the highest DIC concentrations were always observed during winter baseflow conditions for the six catchments considered in this study. Long-term trends for the period 1982 to 2010 for one of the streams showed that DIC concentrations has increased by 9 % during the 28 yr of measurement while no clear trend was found for DOC. Similar increasing trends were also found for conductivity, Ca and Mg. When trends were discretized into individual months, we found a significant linear increase in DIC concentrations with time for September, November and December. In these subarctic catchments, the annual mass of C exported as DIC was in the same order of magnitude as DOC; the average proportion of DIC to the total dissolved C exported was 61 % for the six streams. Furthermore, there was a direct relationship between total runoff and annual dissolved carbon fluxes for these six catchments. These relationships were more prevalent for annual DIC exports than annual DOC exports in this region. Our results also highlight that both DOC and DIC can be important in highlatitude ecosystems. This is particularly relevant in environments where thawing permafrost and changes to subsurface ice due to global warming can influence stream water fluxes of C. The large proportion of stream water DIC flux also has implications on regional C budgets and needs to be considered in order to understand climate-induced feedback mechanisms across the landscape.

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“…Some studies predict that changes in Arctic hydrology will result in greater riverine export of terrestrial OM due to thawing of organic-rich permafrost (Frey and Smith 2005). Other studies suggest that OM export will decrease as permafrost thaws and water flow paths deepen (e.g., Striegl et al 2005Striegl et al , 2007Petrone et al 2006Petrone et al , 2007, either because dissolved OM is trapped in newlythawed mineral soils or respired during longer residence times. At the same time, increased water flow through mineral soils (as opposed to organic rich soils) and increased net N mineralization under warmer conditions may increase hydrologic export of inorganic N (Shaver et al 1992;Jones et al 2005;Greenwald et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Seasonal and hydrologic drivers of dissolved organic matter and nutrients in the upper Kuparuk River, Alaskan Arctic

et al. 2010

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As the planet warms, widespread changes in Arctic hydrology and biogeochemistry have been documented and these changes are expected to accelerate in the future. Improved understanding of the behavior of water-borne constituents in Arctic rivers with varying hydrologic conditions, including seasonal variations in discharge-concentration relationships, will improve our ability to anticipate future changes in biogeochemical budgets due to changing hydrology. We studied the relationship between seasonal water discharge and dissolved organic carbon and nitrogen (DOC and DON) and nutrient concentrations in the upper Kuparuk River, Arctic Alaska. Fluxes of most constituents were highest during initial snowmelt runoff in spring, indicating that this historically under-studied period contributes significantly to total annual export. In particular, the initial snowmelt period (the stream is completely frozen during the winter) accounted for upwards of 35% of total export of DOC and DON estimated for the entire study period. DOC and DON concentrations were positively correlated with discharge whereas nitrate (NO 3 -) and silicate were negatively correlated with discharge throughout the study. However, discharge-specific DOC and DON concentrations (i.e. concentrations compared at the same discharge level) decreased over the summer whereas discharge-specific concentrations of NO 3 -and silicate increased. Soluble reactive phosphorus (SRP) and ammonium (NH 4 ? ) were negatively correlated with discharge during the spring thaw, but were less predictable with respect to discharge thereafter. These data provide valuable information on how Arctic watershed biogeochemistry will be affected by future changes in temperature, snowfall, and rainfall in the Arctic. In particular, our results add to a growing body of research showing that nutrient export per unit of stream discharge, particularly NO 3 -, is increasing in the Arctic.

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Seasonal export of carbon, nitrogen, and major solutes from Alaskan catchments with discontinuous permafrost

Cited by 160 publications

References 62 publications

Temperature and moisture effects on greenhouse gas emissions from deep active-layer boreal soils

Temperature and moisture effects on greenhouse gas emissions from deep active-layer boreal soils

Catchment-scale dissolved carbon concentrations and export estimates across six subarctic streams in northern Sweden

Seasonal and hydrologic drivers of dissolved organic matter and nutrients in the upper Kuparuk River, Alaskan Arctic

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