Pan-arctic trends in terrestrial dissolved organic matter from optical measurements
Climate change is causing extensive warming across arctic regions resulting in permafrost degradation, alterations to regional hydrology, and shifting amounts and composition of dissolved organic matter (DOM) transported by streams and rivers. Here, we characterize the DOM composition and optical pr...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Frontiers Media S.A.
2016-03-01
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| Series: | Frontiers in Earth Science |
| Subjects: | |
| Online Access: | http://journal.frontiersin.org/Journal/10.3389/feart.2016.00025/full |
| _version_ | 1819067179020058624 |
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| author | Paul James Mann Robert GM Spencer Peter J Hernes Johan eSix George R Aiken Suzanne E Tank James W McClelland Kenna D Butler Rachael Y Dyda Robert M Holmes |
| author_facet | Paul James Mann Robert GM Spencer Peter J Hernes Johan eSix George R Aiken Suzanne E Tank James W McClelland Kenna D Butler Rachael Y Dyda Robert M Holmes |
| author_sort | Paul James Mann |
| collection | DOAJ |
| description | Climate change is causing extensive warming across arctic regions resulting in permafrost degradation, alterations to regional hydrology, and shifting amounts and composition of dissolved organic matter (DOM) transported by streams and rivers. Here, we characterize the DOM composition and optical properties of the six largest arctic rivers draining into the Arctic Ocean to examine the ability of optical measurements to provide meaningful insights into terrigenous carbon export patterns and biogeochemical cycling. The chemical composition of aquatic DOM varied with season, spring months were typified by highest lignin phenol and dissolved organic carbon (DOC) concentrations with greater hydrophobic acid content, and lower proportions of hydrophilic compounds, relative to summer and winter months. Chromophoric DOM (CDOM) spectral slope (S275-295) tracked seasonal shifts in DOM composition across river basins. Fluorescence and parallel factor analysis identified seven components across the six Arctic rivers. The ratios of ‘terrestrial humic-like’ versus ‘marine humic-like’ fluorescent components co-varied with lignin monomer ratios over summer and winter months, suggesting fluorescence may provide information on the age and degradation state of riverine DOM. CDOM absorbance (a350) proved a sensitive proxy for lignin phenol concentrations across all six river basins and over the hydrograph, enabling for the first time the development of a single pan-arctic relationship between a350 and terrigenous DOC (R2 = 0.93). Combining this lignin proxy with high-resolution monitoring of a350, pan-arctic estimates of annual lignin flux were calculated to range from 156 to 185 Gg, resulting in shorter and more constrained estimates of terrigenous DOM residence times in the Arctic Ocean (spanning 7 months to 2½ years). Furthermore, multiple linear regression models incorporating both absorbance and fluorescence variables proved capable of explaining much of the variability in lignin composition across rivers and seasons. Our findings suggest that synoptic, high-resolution optical measurements can provide improved understanding of northern high-latitude organic matter cycling and flux, and prove an important technique for capturing future climate-driven changes. |
| first_indexed | 2024-12-21T16:14:08Z |
| format | Article |
| id | doaj.art-7056af62ceb2499ca3199ece32c2218b |
| institution | Directory Open Access Journal |
| issn | 2296-6463 |
| language | English |
| last_indexed | 2024-12-21T16:14:08Z |
| publishDate | 2016-03-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Earth Science |
| spelling | doaj.art-7056af62ceb2499ca3199ece32c2218b2022-12-21T18:57:43ZengFrontiers Media S.A.Frontiers in Earth Science2296-64632016-03-01410.3389/feart.2016.00025171139Pan-arctic trends in terrestrial dissolved organic matter from optical measurementsPaul James Mann0Robert GM Spencer1Peter J Hernes2Johan eSix3George R Aiken4Suzanne E Tank5James W McClelland6Kenna D Butler7Rachael Y Dyda8Robert M Holmes9Northumbria UniversityFlorida State UniversityUniversity of CaliforniaETH-ZurichUnited States Geological SurveyUniversity of AlbertaUniversity of TexasUnited States Geological SurveyUniversity of CaliforniaWoods Hole Research CenterClimate change is causing extensive warming across arctic regions resulting in permafrost degradation, alterations to regional hydrology, and shifting amounts and composition of dissolved organic matter (DOM) transported by streams and rivers. Here, we characterize the DOM composition and optical properties of the six largest arctic rivers draining into the Arctic Ocean to examine the ability of optical measurements to provide meaningful insights into terrigenous carbon export patterns and biogeochemical cycling. The chemical composition of aquatic DOM varied with season, spring months were typified by highest lignin phenol and dissolved organic carbon (DOC) concentrations with greater hydrophobic acid content, and lower proportions of hydrophilic compounds, relative to summer and winter months. Chromophoric DOM (CDOM) spectral slope (S275-295) tracked seasonal shifts in DOM composition across river basins. Fluorescence and parallel factor analysis identified seven components across the six Arctic rivers. The ratios of ‘terrestrial humic-like’ versus ‘marine humic-like’ fluorescent components co-varied with lignin monomer ratios over summer and winter months, suggesting fluorescence may provide information on the age and degradation state of riverine DOM. CDOM absorbance (a350) proved a sensitive proxy for lignin phenol concentrations across all six river basins and over the hydrograph, enabling for the first time the development of a single pan-arctic relationship between a350 and terrigenous DOC (R2 = 0.93). Combining this lignin proxy with high-resolution monitoring of a350, pan-arctic estimates of annual lignin flux were calculated to range from 156 to 185 Gg, resulting in shorter and more constrained estimates of terrigenous DOM residence times in the Arctic Ocean (spanning 7 months to 2½ years). Furthermore, multiple linear regression models incorporating both absorbance and fluorescence variables proved capable of explaining much of the variability in lignin composition across rivers and seasons. Our findings suggest that synoptic, high-resolution optical measurements can provide improved understanding of northern high-latitude organic matter cycling and flux, and prove an important technique for capturing future climate-driven changes.http://journal.frontiersin.org/Journal/10.3389/feart.2016.00025/fullCarbon CycleClimate ChangeLigninfluorescenceArcticDissolved organic carbon (DOC) |
| spellingShingle | Paul James Mann Robert GM Spencer Peter J Hernes Johan eSix George R Aiken Suzanne E Tank James W McClelland Kenna D Butler Rachael Y Dyda Robert M Holmes Pan-arctic trends in terrestrial dissolved organic matter from optical measurements Frontiers in Earth Science Carbon Cycle Climate Change Lignin fluorescence Arctic Dissolved organic carbon (DOC) |
| title | Pan-arctic trends in terrestrial dissolved organic matter from optical measurements |
| title_full | Pan-arctic trends in terrestrial dissolved organic matter from optical measurements |
| title_fullStr | Pan-arctic trends in terrestrial dissolved organic matter from optical measurements |
| title_full_unstemmed | Pan-arctic trends in terrestrial dissolved organic matter from optical measurements |
| title_short | Pan-arctic trends in terrestrial dissolved organic matter from optical measurements |
| title_sort | pan arctic trends in terrestrial dissolved organic matter from optical measurements |
| topic | Carbon Cycle Climate Change Lignin fluorescence Arctic Dissolved organic carbon (DOC) |
| url | http://journal.frontiersin.org/Journal/10.3389/feart.2016.00025/full |
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