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Strong Spatial Gradients in Aquatic Greenhouse Gas Emissions Within Glaciated Stratovolcano Catchments of the Tropical Andes
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Abstract
Inland waters are increasingly being recognized for their key role in the global carbon budget, processing and emitting significant amounts of carbon. Tropical peatlands store some of the highest carbon densities on Earth, but hydrological connectivity’s role in regulating carbon processing and greenhouse gas flux within their headwater stream networks remains poorly understood. We evaluated spatial variability of carbon fluxes across 20 km of stream network in a glacier-fed stratovolcano catchment in the Ecuadorian Andes, measuring dissolved CO2 (pCO2), dissolved oxygen, dissolved methane (pCH4), dissolved organic carbon, specific conductance, pH, temperature, channel geometry, and water velocity. Each stream showed a unique longitudinal pattern of CO2 concentration and flux, indicating that evasion is regulated by localized landscape elements and connectivity. Distinct pCO2-DOC relationships across sub-catchments reflected heterogeneity in carbon sources and processing. Wetland-dominated reaches showed substantially elevated CH4:CO2 ratios relative to glacier and spring-fed reaches, suggesting connectivity to peatland soils drives in-stream methane dynamics. Spring-fed headwaters acted as extreme CO2 point sources, with most evasion occurring within a few hundred meters of groundwater emergence. Recently deglaciated terrain appears to offset carbon emissions and promote net carbon sink behavior. Reactive transport modeling (BioRT-HBV) indicated hydrologic source controlled CO2 delivery, while CH4 differences between similarly shallow-flow-dominated reaches reflected how carbon processing partitioned between the two gases. Collectively, these findings demonstrate that in-stream carbon dynamics vary substantially over small spatial scales, driven by localized landscape elements and hydrologic connectivity, offering new insight into carbon cycling in these understudied ecosystems.
Subject Keywords
Coverage
Spatial
Temporal
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Content
README.md
Data Repository: Aquatic CO₂ and CH₄ Dynamics in Glaciated Páramo Streams, Antisana Water Conservation Area, Ecuador
Author / point of contact: Ellis Clark, University of North Carolina at Chapel Hill (ellisgcl@unc.edu) Associated manuscript: Strong Spatial Gradients in Aquatic Greenhouse Gas Emissions Within Glaciated Stratovolcano Catchments of the Tropical Andes, target journal JGR Biogeosciences (in review/preparation as of dataset publication) Study site: Páramo headwater streams draining the glaciated Antisana stratovolcano, Antisana Water Conservation Area, Ecuador. Field campaign conducted May–June 2025 across four stream sites: GF (Antisana), SF (Yakupamba), LR (Jatunhuayco), and HR (Chuzalongo).
1. Overview
This repository contains field-collected and derived (calculated) data supporting a study of dissolved CO₂ and CH₄ concentrations and air–water gas exchange (evasion) fluxes along four glacier- and páramo-fed stream reaches on Volcán Antisana. Two workbooks are included:
| File | Contents |
|---|---|
Field_Data_Repository.xlsx |
Raw and minimally processed field measurements: waypoint locations, inter-waypoint distances, hydraulic geometry, water chemistry (pH, conductivity, pCO₂, CH₄, DOC/TDN), water level/temperature/pressure, and soil CO₂ flux chamber logs. |
Calculated_Flux_Data_Repository.xlsx |
Derived, reach-scale gas transfer velocities (k600) and CO₂ evasion fluxes calculated from the field data, for waypoints 107–144 (stream reach surveyed 16–18 June 2025). |
Missing or not-applicable values are coded NA throughout both workbooks.
2. Field_Data_Repository.xlsx
2.1 Sheet: Waypoints
Master list of GPS waypoints recorded along all surveyed stream reaches.
| Column | Description | Units |
|---|---|---|
| Waypoint | Unique waypoint ID | integer |
| Date | Date of waypoint collection | date |
| S | Latitude, degrees/minutes (field GPS format, South) | DDD°MM.MMM' |
| W | Longitude, degrees/minutes (field GPS format, West) | DDD°MM.MMM' |
| Elevation (m) | GPS elevation | m |
| Latitude / Longitude | Latitude/longitude in degree-minutes string form (duplicate of S/W) | — |
| Lat Minutes / Long Minutes | Minutes component parsed from S/W | decimal minutes |
| lat# / long# | Decimal-degree latitude/longitude (signed; negative = S/W) | decimal degrees |
2.2 Sheet: Distances by Stream
Waypoints grouped and ordered by stream, with running distance calculated along each stream's flow path.
| Column | Description | Units |
|---|---|---|
| Waypoint, Date, S, W, Elevation (m), Latitude, Longitude, Lat/Long Minutes, lat#/long# | As above | — |
| Stream | Stream site name/abbreviation (Antisana=GF, Yakupamba=SF, Jatunhuayco=LR, Chuzalongo=HR) | text |
| Distance from Last Point | Straight-line distance from the previous waypoint along the stream, computed from lat#/long# | m |
| Distance from Head | Cumulative distance downstream from the stream head (first waypoint) | m |
2.3 Sheet: Level logger
Water pressure/temperature logger deployment log (used to estimate stage/discharge and correct pCO₂ for atmospheric pressure).
| Column | Description | Units |
|---|---|---|
| Waypoint | Associated waypoint | integer |
| Date | Deployment date | date |
| Start Time / End Time | Logger deployment window at the waypoint | time |
| Temp C (water) | Water temperature | °C |
| Pressure kPa (water) | Absolute pressure recorded in-stream | kPa |
| Pressure kPa (atmosphere) | Concurrent barometric (atmospheric) pressure reference | kPa |
2.4 Sheet: Hach
Stream hydraulic geometry and velocity measurements (Hach flow meter, mid-section method).
| Column | Description | Units |
|---|---|---|
| Waypoint | Associated waypoint | integer |
| Date | Measurement date | date |
| Width (m) | Wetted channel width | m |
| Depth (m) | Water depth at measurement point | m |
| Velocity (m/s) | Point velocity | m s⁻¹ |
| Time | Time of measurement | time |
| (unlabeled column, discharge) | Discharge computed via mid-section method (width × depth × velocity) | m³ s⁻¹ |
2.5 Sheet: pH
| Column | Description | Units |
|---|---|---|
| Waypoint, Date, Time | Sample identifiers | — |
| pH | In-situ pH reading | pH units |
2.6 Sheet: Conductivity
| Column | Description | Units |
|---|---|---|
| Waypoint, Date, Time | Sample identifiers | — |
| Conductivity (μS/cm) | Specific conductivity | µS cm⁻¹ |
2.7 Sheet: pCO2
Dissolved CO₂ partial pressure measured in-situ with a Vaisala NDIR CO₂ probe.
| Column | Description | Units |
|---|---|---|
| Waypoint, Date, Time, Alt Time | Sample identifiers (Alt Time = secondary/backup timestamp where recorded) | — |
| pCO2 (ppm) | Raw instrument reading | ppm |
| pCO2 adjusted (uatm) | Reading converted to partial pressure via Henry's Law, temperature- and pressure-corrected | µatm |
2.8 Sheet: CH4
Discrete water samples analyzed for dissolved CH₄ by gas chromatography (headspace equilibration).
| Column | Description | Units |
|---|---|---|
| Waypoint, Date, Time | Sample identifiers | — |
| Bottle # | Sample bottle/vial ID | — |
| Dilution-CH4 | Dilution factor applied prior to GC analysis, where used | ratio |
| [CH4] | Intermediate/raw GC concentration | — |
| Total number of bottles | Bottles collected for the sample | integer |
| Ch4 [uatm] | CH₄ partial pressure computed from GC peak area via headspace equilibration | µatm |
| Dillition CH4 | Secondary dilution-corrected value, where applicable | — |
| Adjusted | Final mass-balance-corrected CH₄ value used in analysis | µatm |
2.9 Sheet: DOC
Discrete water samples analyzed for dissolved organic carbon and total dissolved nitrogen.
| Column | Description | Units |
|---|---|---|
| Waypoint, Date, Time | Sample identifiers | — |
| Bottle # | Sample bottle/vial ID | — |
| DOC (mg/L) | Dissolved organic carbon concentration | mg L⁻¹ |
| TDN (mg/L) | Total dissolved nitrogen concentration | mg L⁻¹ |
3. Calculated_Flux_Data_Repository.xlsx
Contains reach-scale CO₂ evasion flux calculations for waypoints 107–144 (surveyed 16–18 June 2025), derived from the field measurements above following an energy-dissipation-based gas transfer velocity model (k600; cf. Whitmore et al. 2021, Ecosphere). The workbook has two sheets with identical row-for-row content: "Data Repository with Labels" uses descriptive column headers and units for human readers, and "Data Repository for Code" uses short machine-readable field names (no spaces/units) for direct import into R/Python analysis scripts.
| Column (labeled sheet) | Column (code sheet) | Description | Units |
|---|---|---|---|
| Waypoint | waypoint | Waypoint ID (links to Field_Data_Repository.xlsx) |
integer |
| Date of Collection | date | Sample date | date |
| Elevation (m) | elevation | GPS elevation | m |
| Latitude / Longitude | latitude / longitude | Decimal-degree coordinates | decimal degrees |
| pCO2 (ppm) | pCO2 | Raw in-situ CO₂ reading | ppm |
| pH | pH | In-situ pH | pH units |
| Width (m) | width | Wetted channel width | m |
| Velocity (m s-1) | velocity | Mean channel velocity | m s⁻¹ |
| Soil Flux (μmol m-2 s-1) | soil_flux | Diffusive soil CO₂ flux (EosFD chamber) at/near the waypoint | µmol m⁻² s⁻¹ |
| Water Temperature (°C) | water.temp | In-situ water temperature | °C |
| Atmosphere Pressure (kPa) | atmosphere.pressure | Barometric pressure | kPa |
| Distance from Previous Waypoint (m) | distance_from_last_point_m | Reach length between consecutive waypoints | m |
| Distance from Stream Head (m) | distance_from_head_m | Cumulative distance downstream from the stream head | m |
| pCH4 (μM) | CH4 | Dissolved CH₄ concentration | µM |
| Aquatic Partial Pressure CO2 | pCO2w_atm | Water-side CO₂ partial pressure (Henry's Law-converted) | atm |
| Atmospheric Partial Pressure CO2 | pCO2air_atm | Equilibrium atmospheric CO₂ partial pressure used as the reference endmember | atm |
| Slope | slope | Local channel slope between waypoints | m m⁻¹ |
| — | Sc_CO2 | Schmidt number for CO₂ at in-situ water temperature | dimensionless |
| Stream Energy Dissipation Rate (eD, m2 s–3) | eD | Energy dissipation rate (used to parameterize gas transfer velocity) | m² s⁻³ |
| Temperature-Corrected Gas Transfer Velocity (k600, m d-1) | k600 | Gas transfer velocity normalized to Sc = 600 | m d⁻¹ |
| — | k_CO2 | Gas transfer velocity for CO₂, Schmidt-number-corrected from k600 | m d⁻¹ |
| Calculated Flux (mol m-2 d-1) | F_m2_d | Areal CO₂ evasion flux | mol m⁻² d⁻¹ |
| Calculated Flux (μmol m-2 s-1) | — | Areal CO₂ evasion flux (alternate units) | µmol m⁻² s⁻¹ |
| Area of Segment (m2) | area_m2 | Surface area of the stream segment between waypoints (width × reach length) | m² |
| Total Flux of Segment (mol d-1) | F_total | Segment-integrated CO₂ evasion (areal flux × segment area) | mol d⁻¹ |
| Cumulative Flux Downstream (mol d-1) | F_cum | Running cumulative CO₂ evasion summed downstream from the stream head | mol d⁻¹ |
| Insolation (kWh m-2 day-1) | insolation | Daily solar insolation at the waypoint (used in energy-dissipation model inputs) | kWh m⁻² day⁻¹ |
Note: The first waypoint of a reach (no upstream neighbor) has NA for distance-, area-, and cumulative-flux fields, since these require a preceding waypoint.
4. Methods summary
- Location/positioning: Handheld GPS waypoints recorded in degrees/decimal-minutes and converted to decimal degrees.
- Discharge/hydraulic geometry: Mid-section method using a Hach flow meter (width, depth, velocity at sub-sections).
- Dissolved CO₂: In-situ Vaisala NDIR probe readings converted to partial pressure via Henry's Law with temperature and barometric pressure correction.
- Dissolved CH₄: Discrete headspace-equilibration samples analyzed by gas chromatography.
- pH, conductivity, water temperature: In-situ probes.
- DOC/TDN: Discrete filtered water samples, laboratory analysis.
- Soil CO₂ flux: Eosense EosFD forced-diffusion chamber.
- Gas transfer velocity (k600) and evasion flux: Estimated from an energy-dissipation model (channel slope, velocity, discharge) following the approach of Whitmore et al. (2021, Ecosphere), Schmidt-number-corrected to CO₂ at in-situ temperature, and scaled to reach-segment area to compute total and cumulative downstream flux.
5. Data conventions
- Missing, not-collected, or not-applicable values are coded
NA. - Dates are in
YYYY-MM-DDformat (or Excel native date type). - All coordinates are WGS84.
- Negative latitude/longitude values indicate South/West, consistent with the site being south of the equator and west of the prime meridian.
6. Related code/model
Flux and gas transfer velocity calculations, and downstream reactive-transport modeling (BioRT-HBV), were performed in R.
7. Contact
Questions about this dataset should be directed to Ellis Clark (ellisgcl@unc.edu) or Diego Riveros-Iregui (diegori@unc.edu), Department of Environment, Ecology and Energy / Geography, University of North Carolina at Chapel Hill.
Credits
Funding Agencies
This resource was created using funding from the following sources:
| Agency Name | Award Title | Award Number |
|---|---|---|
| National Science Foundation | None | EAR-2317854 |
| National Science Foundation | None | EAR-2317851 |
| National Science Foundation | None | EAR-1847331 |
How to Cite
This resource is shared under the Creative Commons Attribution CC BY.
http://creativecommons.org/licenses/by/4.0/
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