Variability of coloured dissolved organic carbon in seepage humic lakes as related to lake morphometry, catchment characteristics and precipitation.

Ecohydrology ◽  
2014 ◽  
Vol 8 (7) ◽  
pp. 1229-1238 ◽  
Author(s):  
Wojciech Pęczuła
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Lake Morphometry ◽  
Humic Lakes ◽  
Catchment Characteristics

scholarly journals Sources and fate of terrestrial dissolved organic carbon in lakes of a Boreal Plains region recently affected by wildfire

2013 ◽  
Vol 10 (4) ◽  
pp. 6093-6141 ◽  
Author(s):  
D. Olefeldt ◽  
K. J. Devito ◽  
M. R. Turetsky
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Primary Productivity ◽  
Fulvic Acids ◽  
Lake Morphometry ◽  
Humic And Fulvic Acids ◽  
Study Region ◽  
Boreal Plains ◽  
Peat Pore Water ◽  
Surface Geology

Abstract. Downstream mineralization and sedimentation of terrestrial dissolved organic carbon (DOC) render lakes important for landscape carbon cycling in the boreal region, with regulating processes potentially sensitive to perturbations associated with climate change including increased occurrence of wildfire. In this study we assessed chemical composition and reactivity (during both dark and UV incubations) of DOC from lakes and terrestrial sources within a peatland-rich western boreal plains region partially affected by a recent wildfire. While wildfire was found to increase aromaticity of DOC in peat pore-water above the water table, it had no effect on concentrations or composition of DOC from peatland wells and neither affected mineral well or lake DOC characteristics. Lake DOC composition reflected a mixing of peatland and mineral groundwater, with a greater influence of mineral sources to lakes in coarse- than fine-textured settings. Peatland DOC was less biodegradable than mineral DOC, but both mineralization and sedimentation of peatland DOC increased substantially during UV incubations through selective removal of aromatic humic and fulvic acids. DOC composition in lakes with longer residence times had characteristics consistent with increased UV-mediated processing. We estimate that about half of terrestrial DOC inputs had been lost within lakes, mostly due to UV-mediated processes. The importance of within-lake losses of aromatic DOC from peatland sources through UV-mediated processes indicate that terrestrial-aquatic C linkages in the study region are largely disconnected from recent terrestrial primary productivity. Together, our results suggest that characteristics of the study region (climate, surface geology and lake morphometry) render linkages between terrestrial and aquatic C cycling insensitive to the effects of wildfire by determining dominant terrestrial sources and within-lake processes of DOC removal.

scholarly journals Drivers of Dissolved Organic Carbon Mobilization From Forested Headwater Catchments: A Multi Scaled Approach

2021 ◽  
Vol 3 ◽  
Author(s):  
Thomas Adler ◽  
Kristen L. Underwood ◽  
Donna M. Rizzo ◽  
Adrian Harpold ◽  
Gary Sterle ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Acid Deposition ◽  
Iterative Process ◽  
Catchment Scale ◽  
Regional Patterns ◽  
Headwater Catchments ◽  
Catchment Characteristics ◽  
Pattern Approach

Understanding and predicting catchment responses to a regional disturbance is difficult because catchments are spatially heterogeneous systems that exhibit unique moderating characteristics. Changes in precipitation composition in the Northeastern U.S. is one prominent example, where reduction in wet and dry deposition is hypothesized to have caused increased dissolved organic carbon (DOC) export from many northern hemisphere forested catchments; however, findings from different locations contradict each other. Using shifts in acid deposition as a test case, we illustrate an iterative “process and pattern” approach to investigate the role of catchment characteristics in modulating the steam DOC response. We use a novel dataset that integrates regional and catchment-scale atmospheric deposition data, catchment characteristics and co-located stream Q and stream chemistry data. We use these data to investigate opportunities and limitations of a pattern-to-process approach where we explore regional patterns of reduced acid deposition, catchment characteristics and stream DOC response and specific soil processes at select locations. For pattern investigation, we quantify long-term trends of flow-adjusted DOC concentrations in stream water, along with wet deposition trends in sulfate, for USGS headwater catchments using Seasonal Kendall tests and then compare trend results to catchment attributes. Our investigation of climatic, topographic, and hydrologic catchment attributes vs. directionality of DOC trends suggests soil depth and catchment connectivity as possible modulating factors for DOC concentrations. This informed our process-to-pattern investigation, in which we experimentally simulated increased and decreased acid deposition on soil cores from catchments of contrasting long-term DOC response [Sleepers River Research Watershed (SRRW) for long-term increases in DOC and the Susquehanna Shale Hills Critical Zone Observatory (SSHCZO) for long-term decreases in DOC]. SRRW soils generally released more DOC than SSHCZO soils and losses into recovery solutions were higher. Scanning electron microscope imaging indicates a significant DOC contribution from destabilizing soil aggregates mostly from hydrologically disconnected landscape positions. Results from this work illustrate the value of an iterative process and pattern approach to understand catchment-scale response to regional disturbance and suggest opportunities for further investigations.

Seasonal variations of dominant phytoplankton in humic forest lakes

2007 ◽  
Vol 36 (2) ◽  
Author(s):  
Tomasz Joniak
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Water Column ◽  
Humic Substances ◽  
Community Composition ◽  
Seasonal Variations ◽  
Humic Lakes ◽  
Forest Lakes ◽  
Dissolved Humic Substances

Seasonal variations of dominant phytoplankton in humic forest lakesThis work presents the community composition, abundance and seasonal dominance of phytoplankton taxa in three hydrochemically different, mid-forest humic lakes. The largest number of taxa was observed in the oligohumic lake (76), with smaller numbers seen in the mesohumic (42) and polyhumic lakes (37), which were characterized by higher contents of dissolved humic substances carbon (DHSC). Along an increasing gradient of DHSC in a pool of dissolved organic carbon (DOC) the autotrophic algae were seen to disappear, being replaced by taxa with features of facultative heterotrophs and flagellated algae that are able to move in the water column.

pH Tolerance and Metal Toxicity in Populations of the Planktonic Diatom Asterionella: Influences of Synthetic and Natural Dissolved Organic Carbon

1993 ◽  
Vol 50 (1) ◽  
pp. 121-132 ◽  
Author(s):  
Robert W. Gensemer ◽  
Ralph E. H. Smith ◽  
Hamish C. Duthie ◽  
Sherry L. Schiff
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Trace Metal ◽  
Humic Lakes ◽  
Ph Tolerance ◽  
Natural Forms ◽  
Acidic Conditions ◽  
Relative Inability ◽  
Culture Growth ◽  
Chemical Conditions

Two clones of Asterionella ralfsii cf americana Körn. were more tolerant of acidic pH with respect to batch culture growth rate than their congener, A. formosa Hass. The relative inability of A. formosa to satisfy trace metal requirements at lower pH appeared to be a major factor in its reduced tolerance of acidic conditions. The pH tolerance of A. formosa, and at times A. ralfsii, also could be modified when grown in media containing different concentrations of artificial or natural forms of dissolved organic carbon (DOC). Mixed trace metal additions (Cu, Zn, Mn, Fe, and Al) further affected pH tolerance in A. ralfsii both by alleviating limitation and by inducing toxicity, depending on the nature and concentration of DOC. Overall, our results were consistent with pH classification schemes for both A. ralfsii and A. formosa as they are commonly used in paleolimnological pH reconstruction models. However, apparent pH classifications for both Asterionella species could be altered by changes in DOC-mediated trace metal bioavailability. Their assignment to a specific pH category or distribution thus may not represent an inherent biological property of that taxon, but may strongly depend on chemical conditions which often vary in humic lakes subject to acid deposition.

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