scholarly journals Effect of fire on dissolved organic carbon and inorganic solutes in spruce forest in the permafrost region of interior Alaska

2003 ◽  
Vol 49 (1) ◽  
pp. 25-29 ◽  
Author(s):  
Hideaki Shibata ◽  
Kevin C. Petrone ◽  
Larry D. Hinzman ◽  
Richard D. Boone
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Permafrost Region ◽  
Spruce Forest ◽  
Interior Alaska ◽  
Inorganic Solutes

scholarly journals Biodegradability of dissolved organic carbon in permafrost soils and aquatic systems: a meta-analysis

2015 ◽  
Vol 12 (23) ◽  
pp. 6915-6930 ◽  
Author(s):  
J. E. Vonk ◽  
S. E. Tank ◽  
P. J. Mann ◽  
R. G. M. Spencer ◽  
C. C. Treat ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Aquatic Systems ◽  
The Arctic ◽  
Permafrost Region ◽  
Soil Leachate ◽  
Discontinuous Permafrost ◽  
Spatial Coverage ◽  
Continuous Permafrost ◽  
Permafrost Regions

Abstract. As Arctic regions warm and frozen soils thaw, the large organic carbon pool stored in permafrost becomes increasingly vulnerable to decomposition or transport. The transfer of newly mobilized carbon to the atmosphere and its potential influence upon climate change will largely depend on the degradability of carbon delivered to aquatic ecosystems. Dissolved organic carbon (DOC) is a key regulator of aquatic metabolism, yet knowledge of the mechanistic controls on DOC biodegradability is currently poor due to a scarcity of long-term data sets, limited spatial coverage of available data, and methodological diversity. Here, we performed parallel biodegradable DOC (BDOC) experiments at six Arctic sites (16 experiments) using a standardized incubation protocol to examine the effect of methodological differences commonly used in the literature. We also synthesized results from 14 aquatic and soil leachate BDOC studies from across the circum-arctic permafrost region to examine pan-arctic trends in BDOC. An increasing extent of permafrost across the landscape resulted in higher DOC losses in both soil and aquatic systems. We hypothesize that the unique composition of (yedoma) permafrost-derived DOC combined with limited prior microbial processing due to low soil temperature and relatively short flow path lengths and transport times, contributed to a higher overall terrestrial and freshwater DOC loss. Additionally, we found that the fraction of BDOC decreased moving down the fluvial network in continuous permafrost regions, i.e. from streams to large rivers, suggesting that highly biodegradable DOC is lost in headwater streams. We also observed a seasonal (January–December) decrease in BDOC in large streams and rivers, but saw no apparent change in smaller streams or soil leachates. We attribute this seasonal change to a combination of factors including shifts in carbon source, changing DOC residence time related to increasing thaw-depth, increasing water temperatures later in the summer, as well as decreasing hydrologic connectivity between soils and surface water as the thaw season progresses. Our results suggest that future climate warming-induced shifts of continuous permafrost into discontinuous permafrost regions could affect the degradation potential of thaw-released DOC, the amount of BDOC, as well as its variability throughout the Arctic summer. We lastly recommend a standardized BDOC protocol to facilitate the comparison of future work and improve our knowledge of processing and transport of DOC in a changing Arctic.

Unraveling the groundwater transit time control of permafrost derived dissolved organic carbon processing in a hillslope headwater watershed of Qinghai-Tibetan Plateau

2021 ◽  
Author(s):  
Yuqin Sun ◽  
Kale Clauson ◽  
Min Zhou ◽  
Ziyong Sun ◽  
Chunmiao Zheng ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Transit Time ◽  
Mean Transit Time ◽  
Frozen Soil ◽  
Permafrost Region ◽  
Transport Pathways ◽  
Microbial Utilization ◽  
Time Control

<p>Climate warming leads to massive thaws of the northern permafrost that has increased the release of soil organic carbon (SOC) to streams and rivers partly as dissolved organic carbon (DOC). The transport pathways of SOC releasing into porewater and entering into stream are undergoing profound hydrological changes triggered by permafrost thawing, yet the role that the groundwater plays in processing the permafrost derived DOC is ambiguous. Unravelling how subsurface flow affects permafrost sourced DOC processing is important especially in alpine watersheds of high-altitude permafrost region with extensive surface – groundwater interaction. Here, eight types of water were sampled from a small (25 km<sup>2</sup>), alpine (elevation 2960 to 4820 m a.s.l) watershed named Hulugou watershed (HLGW) with variably degraded permafrost in the Qinghai-Tibetan Plateau (QTP) in July and September of 2012, 2013 and 2018. The three end-members (glacier-snow meltwater, precipitation, and frozen soil meltwater) analysis suggested contribution of frozen soil meltwater to all types of water with variable DOC levels (0.4 to 22.6 mg L<sup>-1</sup>, n = 113), as constrained by <em>δ</em><sup>18</sup>O and electrical conductivity (EC). Spatial patterns of DOC quantity and quality between stream and subsurface waters (groundwater, spring, and seepage-II) point to differences in surface – groundwater exchanges in the upper-, mid- and lower stretch of the watershed. To evaluate the extent of DOC loss (ΔDOC), ΔDOC is calculated using an initial DOC (DOC<sub>0</sub>) estimated from mixing of three endmembers, minus the measured DOC concentration. The significant correlations between ΔDOC with proportion of protein-like fluorophores (<em>r</em> = -0.69, <em>p</em> < 0.01) and relatively aromatic C levels (<em>r</em> = -0.62, <em>p</em> = 0.02) indicate ΔDOC corresponding to the extent of microbial utilization of DOC in subsurface environment. Using previously established DOC biodegradation kinetics of 0.25 d<sup>-1</sup> in headwaters of QTP, the mean transit time of groundwater is estimated to be 6 and 20 days based on changes in subsurface ΔDOC of 32% and 74% from the outlet of HLGW for July and September, respectively. The more rapid groundwater transit time corresponds to the higher concentration and more boilable DOC in July (3.5 mg L<sup>-1</sup>, protein-like: 98%) than in September (1.0 mg L<sup>-1</sup>, protein-like: 53±26%). Together with the mass balance of DOC input and export fluxes showing half loss of C in HLGW, our results indicate that rapid groundwater transit time is associated with permafrost derived DOC processing in alpine hillslope subject to warming.</p>

scholarly journals Biodegradability of dissolved organic carbon in permafrost soils and waterways: a meta-analysis

2015 ◽  
Vol 12 (11) ◽  
pp. 8353-8393 ◽  
Author(s):  
J. E. Vonk ◽  
S. E. Tank ◽  
P. J. Mann ◽  
R. G. M. Spencer ◽  
C. C. Treat ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Aquatic Ecosystems ◽  
The Arctic ◽  
Permafrost Region ◽  
Soil Leachate ◽  
Discontinuous Permafrost ◽  
Spatial Coverage ◽  
Continuous Permafrost ◽  
Permafrost Regions

Abstract. As Arctic regions warm, the large organic carbon pool stored in permafrost becomes increasingly vulnerable to thaw and decomposition. The transfer of newly mobilized carbon to the atmosphere and its potential influence upon climate change will largely depend on the reactivity and subsequent fate of carbon delivered to aquatic ecosystems. Dissolved organic carbon (DOC) is a key regulator of aquatic metabolism and its biodegradability will determine the extent and rate of carbon release from aquatic ecosystems to the atmosphere. Knowledge of the mechanistic controls on DOC biodegradability is however currently poor due to a scarcity of long-term data sets, limited spatial coverage of available data, and methodological diversity. Here, we performed parallel biodegradable DOC (BDOC) experiments at six Arctic sites (16 experiments) using a standardized incubation protocol to examine the effect of methodological differences used as common practice in the literature. We further synthesized results from 14 aquatic and soil leachate BDOC studies from across the circum–arctic permafrost region to examine pan-Arctic trends in BDOC. An increasing extent of permafrost across the landscape resulted in higher BDOC losses in both soil and aquatic systems. We hypothesize that the unique composition of permafrost-derived DOC combined with limited prior microbial processing due to low soil temperature and relatively shorter flow path lengths and transport times, resulted in higher overall terrestrial and freshwater BDOC loss. Additionally, we found that the fraction of BDOC decreased moving down the fluvial network in continuous permafrost regions, i.e. from streams to large rivers, suggesting that highly biodegradable DOC is lost in headwater streams. We also observed a seasonal (January–December) decrease in BDOC losses in large streams and rivers, but no apparent change in smaller streams and soil leachates. We attribute this seasonal change to a combination of factors including shifts in carbon source, changing DOC residence time related to increasing thaw-depth, increasing water temperatures later in the summer, as well as decreasing hydrologic connectivity between soils and surface water as the seasons progress. Our results suggest that future, climate warming-induced shifts of continuous permafrost into discontinuous permafrost regions could affect the degradation potential of thaw-released DOC as well as its variability throughout the Arctic summer. We lastly present a recommended standardized BDOC protocol to facilitate the comparison of future work and improve our knowledge of processing and transport of DOC in a changing Arctic.

scholarly journals Dissolved Organic Carbon Turnover in Permafrost-Influenced Watersheds of Interior Alaska: Molecular Insights and the Priming Effect

2019 ◽  
Vol 7 ◽  
Author(s):  
Sadie R. Textor ◽  
Kimberly P. Wickland ◽  
David C. Podgorski ◽  
Sarah Ellen Johnston ◽  
Robert G. M. Spencer
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Priming Effect ◽  
Carbon Turnover ◽  
Interior Alaska

CHARACTERISATION OF DISSOLVED ORGANIC CARBON (DOC) LEACHED FROM LEAVES IN WATER

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Markus Heryanto Langsa
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Total Organic Carbon ◽  
Gas Chromatography Mass Spectrometry ◽  
Pyrolysis Gas ◽  
Pyrolysis Gas Chromatography ◽  
Chromatography Mass Spectrometry ◽  
Pinus Radiate

<p>Penelitian ini bertujuan untuk menentukan senyawa organik khususnya organic karbon terlarut (DOC) dari dua spesies daun tumbuhan (<em>wandoo eucalyptus </em>and <em>pinus radiate, conifer</em>) yang larut dalam air selama periode 5 bulan leaching eksperimen. Kecepatan melarutnya senyawa organic ditentukan secara kuantitatif dan kualitatif menggunakan kombinasi dari beberapa teknik diantaranya Total Organic Carbon (TOC) analyser, Ultraviolet-Visible (UV-VIS) spektrokopi dan pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS).</p><p>Hasil analisis DOC dan UV menunjukkan peningkatan yang tajam dari kelarutan senyawa organic di awal periode pengamatan yang selanjutnya berkurang seiring dengan waktu secara eksponensial. Jumlah relatif senyawa organic yang terlarut tergantung pada luas permukaan, aktifitas mikrobiologi dan jenis sampel tumbuhan (segar atau kering) yang digunakan. Fluktuasi profil DOC dan UV<sub>254</sub> disebabkan oleh aktifitas mikrobiologi. Diperoleh bahwa daun kering lebih mudah terdegradasi menghasilkan senyawa organic dalam air dibandingkan dengan daun segar. Hasil pyrolysis secara umum menunjukkan bahwa senyawa hidrokarbon aromatic dan fenol (dan turunannya) lebih banyak ditemukan pada residue sampel setelah proses leaching kemungkinan karena adanya senyawa lignin atau aktifitas humifikasi mikrobiologi membuktikan bahwa senyawa-senyawa tersebut merupakan komponen penting dalam proses karakterisasi DOC.</p>

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