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TROCAS LÍQUIDAS DO ECOSSISTEMA DO BAIXO
RIO AMAZONAS: DA TERRA PARA O OCEANO E
ATMOSFERA
Obidos
JEFFREY RICHEY &
CENA/Univ. de São Paulo, Univ. de Washington, Univ. Fed. do Amapá
, Univ. do Estado do Amapá, Univ. Fed. do Oeste do Pará, Univ. Fed.
Rural da Amazônia, INPE, Univ. Fed do Rio de Janeiro, Univ. de
Florida
Reunião Anual de Projetos do Programa FAPESP de Pesquisa em
Mudanças Climáticas Globais (PFPMCG), 18-19 Fevereiro 2016
What are the distributions of pCO2* across
the Amazon River, in time and space, as
function of hydrology and “net metabolic
processes?”
pCO2 is 10-20x supersaturated relative to the
atmosphere, leading to high levels of outgassing
to the atmosphere; relevant to the C balance of
the Amazon
The Role of Rivers on the Regional Carbon Cycle
Maria Victoria Ramos Ballester, 19 Fev
*pCO
2
is CO2 dissolved in water
NEE = Δ(PCO2)/ΔT = NET ADVECTION (C*Q) + NET VÁRZEA –
OUTGASSING + [RESP - GROSS PPR]
Macapá N
Macapá S
Almeirim
Obidos
STM50
R. Tapajos
R. Xingu
NET ADVECTION (C*Q) + NET FLOODPLAIN
[I(x) – O(x)] + V(x)
DISCHARGE (Q)
ADCP
Macapá, May 7,8 2014
345,000 m3/s
South (m/s)
North (m/s)
Q (m3/s)
May’14 (Hi)
Nov’14 (Lo) Jul’15 (Early Fall)
△ Q (%)
May’14 (Hi)
Nov’14 (Lo) Jul’15 (Early Fall)
Chl-a (mg/m3)
SPECTRAL RESPONSE
CHL-A
A. Valeiro INPE
METABOLISM : [∫Z(R – GPP) ΔZ]
Respiration ~ 10-15x bigger
than traditional “60-ml
BDO”
Respiration = 0.33 mg C L-1 d-1
4
8
12
16
Hours Incubated
20
LIGNIN
MAJOR COMPONENT OF BIOMASS IN FOREST- WHAT
HAPPENS IN RIVER (AND TO OCEAN)?
Degradation of lignin phenols fuels 30-50%
of bulk respiration in the river
Ward et al. (2013) Nature Geoscience
RESPIRATION : PRODUCTION
(FROM Δ18O-O2)
P has been assumed to be 0 within the main stem of the
Amazon, but…
28,5
80
26,5
70
60
50
25,5
40
24,5
23,5
7/4/15 18:00
% O2 Sat
δ 18O VSMOW
27,5
• Diel sampling schemes
reveal a diel pattern to the
δ18O-O2 values
30
7/5/15 0:00
7/5/15 6:00
20
7/5/15 12:00
High Water: P= 55 ± 13% of R
Low Water: P = 18 ± 6% of R
=> Primary Production is not trivial!
DOES THIS MAKE “MICROBIAL” SENSE?
Proteomics Approach
Most protein in
river are from bacteria
Samples from 24 location in river
>1000 unique proteins typically
identified in each sample.
~200 unique cyanobacterial proteins
identified. Further evidence for
significant primary production in the
main stem
25% of the bacteria
are photosynthetic!
Diversity of primary producers
in the river is high
High Water, Óbidos Center Surface
WORKING THEMES FOR NEE
• Unresolved hydrodynamics from Almeirim to Macapá
• pCO2 remains high, but declines towards Macapá
(outgassing in turbulent water? PPr?)
- Metabolism supported by oxidation of of nominal
recalcitrant lignin-like compounds,
- But lines of evidence for important amounts of
primary production in the (dirty) Amazon River main
stem
- Plant leachates became increasingly more reactive
towards the mouth, in the tributaries, and with algal
injections
Ward et al. (in review) Journal of Geophysical Research: Biogeosciences