Water Balance and Carbon Leaching of a Rainforest Catchment at - - PowerPoint PPT Presentation

CARBONSINK CARBONSINK CARBONSINK CARBONSINK

Water Balance and Carbon Leaching of a Rainforest Catchment at Cuieiras, Central Amazonia

M.J. Waterloo A.D. Nobre W.W.P. Jans

• AD. Cuartas Pineda
• T. Pimentel

D.P. Drucker J.M. Heijmenberg W.N. Gomes M.G. Hodnett

• J. Tomasella et al.

CARBONSINK CARBONSINK CARBONSINK CARBONSINK

Objectives Carbonsink Hydrology

• Overall objective: to study the fate of

carbon once it has been taken up by the vegetation

• To quantify amount of the carbon lost from

the ecosystem through hydrological pathways in a micro-scale catchment

• To assess the sensitivity of the carbon cycle

to changes in the soil moisture status

CARBONSINK CARBONSINK CARBONSINK CARBONSINK

Site Characteristics

• Location: Cuieiras

Reserve of INPA

• Undisturbed

rainforest

• Size 6.37 km2
• Deep soils
• Incised plateau

area, 40 – 100 m a.s.l.)

CARBONSINK CARBONSINK CARBONSINK CARBONSINK

Slope and Groundwater Maps

CARBONSINK CARBONSINK CARBONSINK CARBONSINK

Hydrological Measurements

• Above canopy rainfall (4 locations)
• Throughfall, litter percolate
• River water level and flow velocity (Doppler)
• Electrical conductivity (EC) and temperature
• UV-Vis spectra (NO3, DOC, turbidity)
• Outflow of coarse/fine particulate organic

matter

• Groundwater levels, soil moisture status

CARBONSINK CARBONSINK CARBONSINK CARBONSINK

Rainfall and Surface Runoff

• Period: December 2001 – May 2002
• Total rainfall:

1851 mm

• Total river

discharge: 809 mm

• Difference:

1042 mm

5 10 15 20 25 30 35 40 45 01-Dec-01 31-Dec-01 30-Jan-02 01-Mar-02 31-Mar-02 30-Apr-02 30-May-02 Rainfall (mm), EC (uS/cm) and TOC (mg/l) 1 2 3 4 5 6 7 8 9 10 Discharge (m3/s) Rainfall EC TOC Discharge

CARBONSINK CARBONSINK CARBONSINK CARBONSINK

Possible Sources of C to Streamflow

• (Rainfall) and throughfall
• Litter percolate, overland flow and lateral

sub-surface flow (valley)

• Shallow groundwater flow in the valley
• Groundwater flow from headwater seepage

areas

• Deep groundwater flow from plateau areas

CARBONSINK CARBONSINK CARBONSINK CARBONSINK

UV-Vis Spectrolyser Measurements

• Measures absorbance of radiation in the

ultraviolet and visual range (200-700 nm wavelength)

• Different chemical components absorb at

different wavelengths (Π-bonds) absorbance spectra

• Reference: distilled water zero

absorbance

• Organic substances absorb mainly in the

230 – 340 nm wavelength band

CARBONSINK CARBONSINK CARBONSINK CARBONSINK

S::can UV-Vis Spectra Cuieiras

10 20 30 40 50 60 70 80 90 100 200 250 300 350 400 450 500 550 Wavelength [nm] Absorption [m-1] Rainfall (4 uS/cm) Throughfall (8 uS/cm) Litter percolate (26 uS/cm) Stormflow, high (32 uS/cm) Stormflow, medium (24 uS/cm) Stormflow, low (22 uS/cm) Baseflow, high (20 uS/cm) Groundwater plateau (12 uS/cm) Groundwater valley (44 uS/cm) NO3 Organic carbon Colour, turbidity and suspended

CARBONSINK CARBONSINK CARBONSINK CARBONSINK

Discharge, EC and DOC

5 10 15 20 25 30 35 20-Feb 21-Feb 22-Feb 23-Feb 24-Feb 25-Feb 26-Feb Rainfall, EC and DOC 1 2 3 4 5 6 Streamflow

EC [uS/cm] DOC (254 nm) [mg/l] Rainfall [mm] Streamflow [m3/s]

CARBONSINK CARBONSINK CARBONSINK CARBONSINK

Differences between water types

• 30
• 20
• 10

10 20 30 40 50 60 200 250 300 350 400 450 Wavelength [nm] absorbtion difference [m-1] Stormflow-litter Stormflow-valley gw Stormflow-baseflow

CARBONSINK CARBONSINK CARBONSINK CARBONSINK

Discharge versus EC and DOC

8 12 16 20 24 28 32 36 1 2 3 4 5 6

Discharge [m3/s] EC [uS/cm] and DOC [mg/l] EC DOC

CARBONSINK CARBONSINK CARBONSINK CARBONSINK

Carbon Leaching Estimate

• Combining the half-hourly stream discharge

data with corresponding DOC concentrations yields a carbon leaching value of 0.2 t C ha-1 from December 2001 – May 2002

• Minimum estimate because transport of

inorganic carbon and particulate carbon in streamwater, and losses of DOC in groundwater have not yet been included.

• Annual value about 0.5 t C ha –1???