scholarly journals DOC transport and export in a dynamic tropical catchment

2019 ◽  
Author(s):  
Ricardo Sánchez-Murillo
Keyword(s):  
Organic Carbon ◽  
Hot Spot ◽  
Scale Model ◽  
Storm Events ◽  
Key Factors ◽  
Catchment Scale ◽  
Carbon Export ◽  
Stream Discharge ◽  
Cross Correlation Analysis ◽  
Doc Export

Dissolved organic carbon (DOC) transport and export from headwater forests into freshwaters in highly dynamic tropical catchments are still understudied. Here, we present a DOC analysis (2017) in a pristine and small (~2.6 km2) tropical catchment of Costa Rica. Storm flows governed a rapid surface and lateral allochthonous DOC transport (62.2% of the annual DOC export). Cross-correlation analysis of rainfall and stream discharge indicated that DOC transport occurred on average ~1.25 hours after the rainfall maxima, with large contributions of event water, ranging from 42.4±0.3% up to 98.2±0.3% of the total discharge. Carbon export flux (annual mean=6.7±0.1 g C m-2 yr-1) was greater than values reported in subtropical and temperate catchments. Specific ultraviolet absorbance indicated a mixture of hydrophobic humic and hydrophilic non-humic matter during both baseflow and storm events. Our results highlight the rapid storm-driven DOC transport and export as well as low biogeochemical attenuation during baseflow episodes in a climate sensitive hot-spot. By understanding the key factors controlling the amount of organic carbon transported to streams in dynamic tropical landscapes, better global and catchment-scale model assessments, conservation practices, and water treatment innovations can be identified.

scholarly journals Hydrological processes and permafrost regulate magnitude, source and chemical characteristics of dissolved organic carbon export in a peatland catchment of northeastern China

2017 ◽  
Author(s):  
Yuedong Guo ◽  
Changchun Song ◽  
Wenwen Tan ◽  
Xianwei Wang ◽  
Yongzheng Lu
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Climate Warming ◽  
Northeastern China ◽  
Organic Layer ◽  
Chemical Characteristics ◽  
Carbon Export ◽  
Study Region ◽  
Growing Seasons ◽  
Doc Export

Abstract. Permafrost thawing in peatland has the potential to alter the catchment export of dissolved organic carbon (DOC), thus influencing carbon cycling in linked aquatic and ocean ecosystems. However, peatland along the southern margins of Eurasian permafrost are seldom examined in spite of the presence of considerable risks associated with degradation due to climate warming. This study examines dynamics of DOC export from a permafrost peatland catchment located in northeastern China during the growing seasons of 2012 to 2014. Our findings show that runoff processes affect observed DOC concentrations, magnitudes, sources, and chemical characteristics of stream discharge. The entire catchment exhibits strong potential for annual DOC exporting (4.87 g C m−2), and DOC from the peatland landscape alone is estimated to amount to 12.89 g C m−2. Annual DOC export processes are closely related to total discharge levels, and floods contribute to approximately 85 % of DOC export levels. Flood volumes derived mainly from peat pore water stored in the upper organic layer of the soil profile prior to rainfall events, creating a strong linkage between discharge and DOC concentrations. DOC source and chemical characteristics, as indicated by three fluorescence indexes, have changed regularly according to source shifts occurring as a result of flood and baseflow processes. A deepening of the active layer due to climate warming should elevate proportions of microbial-originated DOC in the baseflow. Given expected future increases in precipitation, our results show that the magnitude of DOC exports from the study region will increase.

scholarly journals Organic carbon sequestration and discharge from a deciduous forest catchment in Korea

2009 ◽  
Vol 6 (5) ◽  
pp. 10089-10120
Author(s):  
S. J. Kim ◽  
J. Kim ◽  
K. Kim
Keyword(s):  
Organic Carbon ◽  
Summer Monsoon ◽  
Deciduous Forest ◽  
Surface Discharge ◽  
Storm Events ◽  
Monsoon Period ◽  
Stream Discharge ◽  
Forest Catchment ◽  
Runoff Discharge ◽  
Annual Discharge

Abstract. Soil infiltration and surface discharge of precipitation are critical processes that affect the sequestration and discharge of dissolved organic carbon (DOC) and particulate organic carbon (POC) in forested catchments. Both DOC and POC are highly concentrated in the soil surface in most forest ecosystems and their discharge may not be negligible particularly under the monsoon climate. In East Asia, however, there are little data available to evaluate the role of such processes in forest carbon budget. In this paper, we address two basic questions: 1) how does stream discharge respond to storm events in a forest catchment? and 2) how much DOC and POC are discharged from the catchment particularly during the summer monsoon period? To answer these questions, we collected hydrological data (e.g., precipitation, soil moisture, runoff discharge, groundwater level) and conducted hydrochemical analyses (including DOC, POC, and six tracers) for a deciduous forest catchment in Gwangneung National Arboretum in west-central Korea. Based on the end-member mixing analysis of the six storm events during the summer monsoon in 2005, the surface discharge was estimated as 30 to 80% of the total runoff discharge. The stream discharge responded to precipitation within 12 h during these storm events. The annual discharge of DOC and POC from the catchment was estimated as 0.04 and 0.05 t C ha−1 yr−1, respectively. Approximately 70% of the annual organic carbon efflux occurred during the summer monsoon period. Overall, the annual discharge of organic carbon was estimated to be 4 to 14% of the net ecosystem carbon exchange (NEE) obtained by eddy covariance technique at the same site. Considering the current trends of increasing intensity and amount of summer rainfall and the large interannual variability in NEE, ignoring the organic carbon discharge from forest ecosystems would result in an overestimation (underestimation) of the strength of forests as a carbon sink (source) in the monsoon East Asia.

scholarly journals High-resolution phosphorus transfers at the catchment scale: the hidden importance of non-storm transfers

2005 ◽  
Vol 9 (6) ◽  
pp. 685-691 ◽  
Author(s):  
P. Jordan ◽  
J. Arnscheidt ◽  
H. McGrogan ◽  
S. McCormick
Keyword(s):  
High Resolution ◽  
Northern Ireland ◽  
Total Phosphorus ◽  
Continuous Flow ◽  
Storm Events ◽  
Catchment Scale ◽  
Discharge Data ◽  
Lough Neagh ◽  
Stream Discharge ◽  
Sampling Regime

Abstract. High-resolution measurements of total phosphorus (TP) concentrations in a stream draining a 5 km2 agricultural catchment (a sub-catchment of Lough Neagh in Northern Ireland) were made every 10 min by continuous flow instrumentation using new homogenisation, digestion and colorimetric phases. Concurrently, rainfall and stream discharge data were collected at 5 and 15 min intervals. Major P flushing episodes during storm events peaked on the rising limbs of storm hydrographs. A period of baseflow also indicated the importance of other sources that maintain the stream in a eutrophic state between storm events. These data provide insights into catchment processes that conform to definite patterns that, in a coarser sampling regime, might ordinarily be attributed to sampling and analytical "noise".

scholarly journals Temperature controls production but hydrology controls export of dissolved organic carbon at the catchment scale

2019 ◽  
Author(s):  
Hang Wen ◽  
Julia Perdrial ◽  
Susana Bernal ◽  
Benjamin W. Abbott ◽  
Rémi Dupas ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Soil Water ◽  
Flow Regime ◽  
Production Rate ◽  
Low Flow ◽  
Seasonal Temperature ◽  
Catchment Scale ◽  
Doc Export ◽  
Doc Production

Abstract. Lateral carbon flux through river networks is an important and poorly-understood component of the global carbon budget. This work investigates how temperature and hydrology control the production and export of dissolved organic carbon (DOC) in the Susquehanna Shale Hills Critical Zone Observatory in Pennsylvania, USA. We applied the catchment-scale hydro-biogeochemical reactive transport model BioRT-Flux-PIHM to simulate the DOC dynamics. We estimated the daily DOC production rate (Rp; the sum of local DOC production rates in individual modeling grid cell) and the daily DOC export rate (Re; the product of concentration and discharge at the stream outlet) to downstream ecosystems. Simulations showed that Rp varied by less than an order of magnitude and primarily hinged on seasonal temperature change. In contrast, Re varied by more than three orders of magnitude with a strong dependence on discharge and hydrological connectivity. During summer, high temperatures led to high atmospheric water demand (and evapotranspiration) that dried and disconnected hillslope to stream. Rp reached its maximum but Re was at its minimum. The stream only exported DOC from the organic-poor groundwater and from soil water in the narrow organic-rich swales with enriched DOC such that DOC accumulated in the catchment. During the wet period (winter and spring), Rp reached its minimum but Re peaked because the stream was re-connected to a greater uphill area, flushing out the stored DOC. The model reproduced the observed concentration discharge (C–Q) relationship characterized by a flushing-dilution pattern with a rise in concentrations to a maximum (flushing) at a threshold discharge and then followed a general dilution with concentrations decreasing with discharge. This pattern was explained by the comparable contribution of organic-poor deeper groundwater and soil water from organic-rich swales at the minimum flow, maximized percentage contribution of soil water from organic-rich swales at the low flow regime, and increased contribution of uphill soil water interflow from uphill with less DOC at the high flow regime. This pattern persisted regardless of DOC production rate as long as the contribution of deeper groundwater flow remained low ( 18 %, the flushing-dilution C–Q pattern shifted towards a flushing-only pattern with DOC concentrations increasing with discharge. This study illustrates the temporal asynchrony of DOC production, mostly controlled by temperature, and DOC export, primarily governed by hydrological flow paths at the catchment scale. The occurrence of warmer and more extreme hydrological events in the future could accentuate this asynchrony, with major lateral export of DOC dominated by a few major storm events whereas DOC is produced and stored in the catchment in the prolonged drought periods.

Clarify the dependency of controlling factors in DOC transport in small mountainous rivers by redundancy analysis

2020 ◽  
Author(s):  
En-Ru Liu ◽  
Yu-Ting Shih ◽  
Li-Chin Lee
Keyword(s):  
Organic Carbon ◽  
Human Activities ◽  
Redundancy Analysis ◽  
Controlling Factors ◽  
Catchment Management ◽  
Catchment Scale ◽  
Ungauged Catchments ◽  
Doc Export ◽  
Explained Variance ◽  
Small Mountainous Rivers

<p>Dissolved organic carbon (DOC) serves as one of the major energy sources in aquatic ecosystems, which is an important pathway connecting terrestrial and marine carbon reservoirs. DOC transport at catchment scale is recognized as being regulated by runoff, slope, soil organic carbon (SOC), biome, and wetland proportion; however, the controls in subtropical small mountainous rivers (SMRs) is rarely discovered before. This study investigated DOC export in 19 catchments in northern Taiwan supplemented with landscape and land use dataset to characterize the controlling factors of DOC transport. Meanwhile, the principle component analysis (PCA) and redundancy analysis (RDA) are applied to untangle the dependence of the controlling factors. Results showed that DOC concentration in Taiwan is very low at approx. 0.8 mg L<sup>-1</sup>, yet the annual DOC yields of the 19 catchments is around 25.23 kg ha<sup>-1</sup> yr<sup>-1</sup>, which is much higher than the global mean (14.4–19.3 kg-C ha<sup>-1</sup> yr<sup>-1</sup>). PCA and RDA shows that the human activities and landscape can explain 87% and 77% of the explained variance, yet runoff play an independent role in DOC transport.  Excluding the overlap, human activities and landscape only accounts for 15 % and 5% of the explained variance, respectively. The overlap between the two components are as high as 72%, indicating the two components could not be separated subjectively. Conclusively, DOC export is mostly dominated by human activities and landscape together, which suggests that they should be considered simultaneously. Besides, DOC yield is positively correlated with streamflow and SOC, but negatively correlated with slope gradient. Our study suggests that interpretation of spatial variation in DOC export should address the overlap between human activities and landscape, which can help predicting the ungauged catchments in catchment management.</p>

scholarly journals Organic carbon efflux from a deciduous forest catchment in Korea

2010 ◽  
Vol 7 (4) ◽  
pp. 1323-1334 ◽  
Author(s):  
S. J. Kim ◽  
J. Kim ◽  
K. Kim
Keyword(s):  
Organic Carbon ◽  
Summer Monsoon ◽  
Forest Ecosystems ◽  
Deciduous Forest ◽  
Surface Discharge ◽  
Storm Events ◽  
Monsoon Period ◽  
Stream Discharge ◽  
Forest Catchment ◽  
Runoff Discharge

Abstract. Soil infiltration and surface discharge of precipitation are critical processes that affect the efflux of Dissolved Organic Carbon (DOC) and Particulate Organic Carbon (POC) in forested catchments. Concentrations of DOC and POC can be very high in the soil surface in most forest ecosystems and their efflux may not be negligible particularly under the monsoon climate. In East Asia, however, there are little data available to evaluate the role of such processes in forest carbon budget. In this paper, we address two basic questions: (1) how does stream discharge respond to storm events in a forest catchment? and (2) how much DOC and POC are exported from the catchment particularly during the summer monsoon period? To answer these questions, we collected hydrological data (e.g., precipitation, soil moisture, runoff discharge, groundwater level) and conducted hydrochemical analyses (including DOC, POC, and six tracers) in a deciduous forest catchment in Gwangneung National Arboretum in west-central Korea. Based on the end-member mixing analysis of the six storm events during the summer monsoon in 2005, the surface discharge was estimated as 30 to 80% of the total runoff discharge. The stream discharge responded to precipitation within 12 h during these storm events. The annual efflux of DOC and POC from the catchment was estimated as 0.04 and 0.05 t C ha−1 yr−1, respectively. Approximately 70% of the annual organic carbon efflux occurred during the summer monsoon period. Overall, the annual efflux of organic carbon was estimated to be about 10% of the Net Ecosystem carbon Exchange (NEE) obtained by eddy covariance measurement at the same site. Considering the current trends of increasing intensity and amount of summer rainfall and the large interannual variability in NEE, ignoring the organic carbon efflux from forest catchments would result in an inaccurate estimation of the carbon sink strength of forest ecosystems in the monsoon East Asia.

scholarly journals Landscape controls on riverine export of dissolved organic carbon from Great Britain

2021 ◽  
Author(s):  
Jennifer L. Williamson ◽  
Andrew Tye ◽  
Dan J. Lapworth ◽  
Don Monteith ◽  
Richard Sanders ◽  
...  
Keyword(s):  
Land Use ◽  
Great Britain ◽  
Population Density ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Forest Cover ◽  
River Systems ◽  
C Cycle ◽  
Global Land ◽  
Doc Export

AbstractThe dissolved organic carbon (DOC) export from land to ocean via rivers is a significant term in the global C cycle, and has been modified in many areas by human activity. DOC exports from large global rivers are fairly well quantified, but those from smaller river systems, including those draining oceanic regions, are generally under-represented in global syntheses. Given that these regions typically have high runoff and high peat cover, they may exert a disproportionate influence on the global land–ocean DOC export. Here we describe a comprehensive new assessment of the annual riverine DOC export to estuaries across the island of Great Britain (GB), which spans the latitude range 50–60° N with strong spatial gradients of topography, soils, rainfall, land use and population density. DOC yields (export per unit area) were positively related to and best predicted by rainfall, peat extent and forest cover, but relatively insensitive to population density or agricultural development. Based on an empirical relationship with land use and rainfall we estimate that the DOC export from the GB land area to the freshwater-seawater interface was 1.15 Tg C year−1 in 2017. The average yield for GB rivers is 5.04 g C m−2 year−1, higher than most of the world’s major rivers, including those of the humid tropics and Arctic, supporting the conclusion that under-representation of smaller river systems draining peat-rich areas could lead to under-estimation of the global land–ocean DOC export. The main anthropogenic factor influencing the spatial distribution of GB DOC exports appears to be upland conifer plantation forestry, which is estimated to have raised the overall DOC export by 0.168 Tg C year−1. This is equivalent to 15% of the estimated current rate of net CO2 uptake by British forests. With the UK and many other countries seeking to expand plantation forest cover for climate change mitigation, this ‘leak in the ecosystem’ should be incorporated in future assessments of the CO2 sequestration potential of forest planting strategies.

scholarly journals Traces of sunlight in the organic matter biogeochemistry of two shallow subarctic lakes

2021 ◽  
Author(s):  
Marttiina V. Rantala ◽  
Carsten Meyer-Jacob ◽  
E. Henriikka Kivilä ◽  
Tomi P. Luoto ◽  
Antti. E. K. Ojala ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Lake Sediments ◽  
Lake Water ◽  
Human Impacts ◽  
Global Environmental Change ◽  
Carbon Export ◽  
Subarctic Lakes ◽  
Carbon Regulation ◽  
In Situ Experiments

AbstractGlobal environmental change alters the production, terrestrial export, and photodegradation of organic carbon in northern lakes. Sedimentary biogeochemical records can provide a unique means to understand the nature of these changes over long time scales, where observational data fall short. We deployed in situ experiments on two shallow subarctic lakes with contrasting light regimes; a clear tundra lake and a dark woodland lake, to first investigate the photochemical transformation of carbon and nitrogen elemental (C/N ratio) and isotope (δ13C, δ15N) composition in lake water particulate organic matter (POM) for downcore inferences. We then explored elemental, isotopic, and spectral (inferred lake water total organic carbon [TOC] and sediment chlorophyll a [CHLa]) fingerprints in the lake sediments to trace changes in aquatic production, terrestrial inputs and photodegradation before and after profound human impacts on the global carbon cycle prompted by industrialization. POM pool in both lakes displayed tentative evidence of UV photoreactivity, reflected as increasing δ13C and decreasing C/N values. Through time, the tundra lake sediments traced subtle shifts in primary production, while the woodland lake carried signals of changing terrestrial contributions, indicating shifts in terrestrial carbon export but possibly also photodegradation rates. Under global human impact, both lakes irrespective of their distinct carbon regimes displayed evidence of increased productivity but no conspicuous signs of increased terrestrial influence. Overall, sediment biogeochemistry can integrate a wealth of information on carbon regulation in northern lakes, while our results also point to the importance of considering the entire spectrum of photobiogeochemical fingerprints in sedimentary studies.

Modelling scenarios of soil properties and managements in olive groves at the micro-catchment scale with the AnnAGNPS model to quantify organic carbon

CATENA ◽  
2021 ◽  
Vol 203 ◽  
pp. 105333
Author(s):  
E.V. Taguas ◽  
R.L. Bingner ◽  
H.G. Momm ◽  
R. Wells ◽  
M.A. Locke
Keyword(s):  
Organic Carbon ◽  
Soil Properties ◽  
Catchment Scale ◽  
Olive Groves
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