Pathways and Mechanisms for Removal of Dissolved Organic Carbon from Leaf Leachate in Streams

1981 ◽  
Vol 38 (1) ◽  
pp. 68-76 ◽  
Author(s):  
Clifford N. Dahm
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Clay Minerals ◽  
Iron Oxides ◽  
Amorphous Solid ◽  
Microbial Utilization ◽  
Physical Chemical ◽  
Fine Particulate ◽  
Solid Phases ◽  
Aluminum And Iron Oxides

Removal of dissolved organic carbon (DOC) from water resulting from adsorption and microbial uptake was examined to determine the importance of biotic and abiotic pathways. Physical–chemical adsorption to components of the stream sediment or water and biotic assimilation associated with the microbial population was determined in recirculating chambers utilizing leachate from alder (Alnus rubra). Adsorptive mechanisms were further separated into interactions involving (1) specific clay minerals, (2) amorphous solid phases of hydrous aluminum and iron oxides, and (3) fine particulate organic matter. Physical–chemical adsorptive mechanisms for alder leachate removal exhibited rapid kinetic equilibration between the DOC and solid phases, but only a specific fraction of the DOC, likely containing certain chemical functional groups, was adsorbed. The amorphous aluminum and iron oxides possessed a much higher potential capacity than the clay minerals or fine particulate organics for DOC adsorption. Microbial uptake of DOC from the alder leachate was kinetically slower than adsorptive uptake. However, microbial activity was overall much more effective in the removal and degradation of the total DOC pool leached from alder leaves. Over a 48-h period, 97% of added 14C labeled leachate was removed from solution by adsorption (~ 20%) and microbial utilization (~ 77%). The rate of microbial uptake was 45 μg C/g sediment C∙h−1 or 14 mg C∙m−2∙h−1.

Sorption of dissolved organic carbon by hydrous aluminum and iron oxides occurring at the confluence of Deer Creek with the Snake River, Summit County, Colorado

1992 ◽  
Vol 26 (7) ◽  
pp. 1388-1396 ◽  
Author(s):  
Diane M. McKnight ◽  
Kenneth E. Bencala ◽  
Gary W. Zellweger ◽  
George R. Aiken ◽  
Gerald L. Feder ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Iron Oxides ◽  
Snake River ◽  
Deer Creek ◽  
Aluminum And Iron Oxides

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>

Leaching and microbial utilization of dissolved organic carbon from leaves of Spartina alterniflora

1976 ◽  
Vol 4 (4) ◽  
pp. 467-471 ◽  
Author(s):  
John L. Gallagher ◽  
William J. Pfeiffer ◽  
Lawrence R. Pomeroy
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Spartina Alterniflora ◽  
Microbial Utilization
Sign in / Sign up

Export Citation Format

Share Document