Wednesday, June 1, 2011

NOx and O3 and mangrove

Biosphere-atmosphere exchange of NOx in the tropical mangrove forest
D. Ganguly,1 M. Dey,1 S. Sen,2 and T. K. Jana1
Received 8 September 2008; revised 20 July 2009; accepted 3 September 2009; published 2
December 2009.
[1] Biosphere-atmosphere exchange of NOx at the Sundarban mangrove forest along
the northeast coast of the Bay of Bengal, India, showed uptake rates of -0.84 to
-1.63 ng N m-2
s-1 during the day and both uptake and emission rates of -0.36 to
5.19 ng N m-2
during the night from September to February. However, during the
period from March to August , NOx emission ranged between 0.34 and 2.13 ng N m-2
and 0.88 and 3.26 ng N m-2
in dayt ime and night t ime, respect ively. During the
postmonsoon period, NOx uptake could be att ributed to mangrove stomatal act ivity during
the day. Mangroves absorbed nit rogen from both the soil and the atmosphere. Seasonal
and diurnal variability of NOx and O3 is part ly due to plant growth in the postmonsoon
period. In addit ion to the NOx-O3 photochemical cycle, stomatal uptake of NOx could
also be an important process for keeping a low-ozone state at the land-ocean boundary of
the northeast coast of the Bay of Bengal.
Citation: Ganguly, D., M. Dey, S. Sen, and T. K. Jana (2009), Biosphere-atmosphere ex tropical mangrove forest, J. Geophys. Res., 114, G04014, doi:10.1029/2008JG000852

information of sundarban

Climate in the region is characterized by the southwest
monsoon (JuneeSeptember), north east monsoon or post-monsoon
(October to January) and pre-monsoon (FebruaryeMay); 70e80%
of annual rain fall occurs during the summer monsoon (South west
monsoon), resulting in high river discharge (2952 and 11,
897 m3 s 1), which gradually diminish to 900e1500 m3 s 1 during
non emonsoonal months (Mukhopadhyay et al., 2006).

Study area

Sundarbans (21 320 and 22 400
N; 88 050 and 89 E), a natural mangrove forest, which is part of the
estuary associated with the river Ganges, on the northeast coast of
the Bay of Bengal, covering a total area of 9630 km2 out of which
4264 km2 comprising intertidal habitat. The area is covered with
thick mangroves, which can be treated as forest and aquatic sub
ecosystems (1781 km2). In 1985, the Indian Sundarban was
included in UNESCO’s list of world heritage site and in 1989; India
designated 9360 km2 of Sundarban as a law protected forest. In
1985 the area of Sundarban forestwas about 20,000 km2 but now is
only 9630 km2, out of which about 4200 km2 is mangrove forest. It
is the last frontier of Bengal flood plains, sprawling archipelago of
102 islands out of which 54 are impacted.
The tidal Islands at the central positions show elevations of the
order of 3e8mfrom mean sea level. The Ganges drains much of the
Sundarban slopes of the Himalayan and delivers an enormous
amount of sediment (324 x106 t annually) to the Bengal fan. The
Hooghly estuary, a tributary of the river Ganges, is a main artery of
the Sundarban mangrove ecosystem and is dominated by fresh
water discharge from Farrakka dam, which is located 285 km
upstream from the mouth of the river. Tide in the study area is
semidiurnal with tidal amplitude, i.e., 2.5e7 m. Mean current
velocities ranges between 117 and 108 cm s 1 during low tide and
high tide, respectively (Mukhopadhyay et al., 2006).

Arsenic in Mangrove ecosystem

Biogeochemical controls of arsenic occurrence and mobility in the
Indian Sundarban mangrove ecosystem
S.K. Mandal a, Mitali Dey b, D. Ganguly b, S. Sen c, T.K. Jana b,*
a Sundarban Hazi Desarat College, Pathankhali, 24 Pgs (South), India
b Department of Marine Science, Calcutta University, 35, B.C. Road, Kolkata, Kolkata 700019,
India, c Department of Chemist ry, 92, A.P.C. Road, Kolkata 700009, India
This study aims to invest igate the cont rol of arsenic dist ribut ion by biogeochemical processes in
the Indian Sundarban mangrove ecosystem and the importance of this ecosystem as an arsenic
source for surrounding coastal water. The As(V)/As(III) rat io was found to be significant ly lower
in both surface and pore waters compared to sea water, which could be at t ributed to
biogeochemical interconversion of these arsenic forms. The biological uptake of arsenic due to
primary and benthic product ion occurs during the post -monsoon season, and is followed by the
release of arsenic during the biochemical degradat ion and dissolut ion of plankton in the premonsoon
season. These results suggest that arsenic is immobilized during incorporat ion into the
arsenic-bearing init ial phase, and unlikely to be released into pore water unt il the complete
microbial degradat ion of arsenic-bearing organic compounds.
_ 2009 Elsevier Ltd. All rights reserved.
Citation: Mandal, S.K., et al. (2009) Biogeochemical controls of arsenic occurrence and mobility in
the ... Mar. Pollut. Bulldoi:10.1016/j.marpolbul.2009.01.010

Radiation budget at Sundarban mangrove forest

Energy dynamics and i ts implication to biosphere–atmosphere exchange of CO2, H2O and
CH4 in a tropical mangrove forest canopy
D. Ganguly, M. Dey, S.K. Mandal, T.K. De, T.K. Jana_
Department of Marine Science, Calcutta University, 35, B.C. Road, Kolkata 70019, India
Received 6 September 2007; received in revised form 11 January 2008; accepted 11 January 2008
Amount of radiant energy (short wave) available to drive biosphere–atmosphere exchange of
CO2, H2O, CH4 and for t ransfer into other energy forms were determined for a t ropical
mangrove forest at the land ocean boundary of north-east (NE) coast of Bay of Bengal from
January to December 2006. The mean annual incoming short wave radiat ion (435732.8Wm-2)
was part it ioned into 29% sensible heat , 35% latent heat , 4% ground heat , 7% physical storage
energy and 10% photosynthet ic storage energy. The mean budget closing energy flux
(68.96724.6Wm-2) or, budget error was 15.8% of incoming short wave radiat ion. In Varimax
factor analysis, budget closing energy flux showed high loading in associat ion with leaf
chlorophyll of different mangrove species, indicat ing its major role for reflect ivity of the surface
for short wave. There was significant seasonality in CO2 exchange with net primary product ivity
of 14.1 μmolm-2 s-1. The mean methane emission was found higher (7.29 μgm-2 s-1) during the
dayt ime than that of night t ime (1.37 μgm-2 s-1) with maximum methane emission rates of 36.1
and 21.1 mgm-2 s-1 in December and January, respect ively. Stepwise mult iple regression analysis
between storage energy [DHs(P)] and fluxes of CO2, CH4, H (sensible heat), HL (latent heat of
evaporat ion), DR (budget closer energy) showed that the combined explained variability for CO2
flux, evapot ranspirat ion and budget closer energy (39%) was less than that of CH4 and sensible
heat flux (46%). The extent of warming effect by CH4 and sensible heat flux was predominant
over the resultant cooling effect due to the processes such as photosynthesis, evapot ranspirat ion
and albedo. The mangrove forest with two t rademarks of low albedo and high surface roughness
was poorly coupled to the environment .
2008 Elsevier Ltd. All rights reserved.
Citation : Ganguly D. et al. (2008) Energy dynamics and its implication to biosphere–atmosphere exchange of CO2, H2O and CH4 in a tropical mangrove forest canopy, Atmospheric Environment 42, 4172–4184,

Carbon at Indian Sundarban

R. Ray, D. Ganguly, C. Chowdhury, M. Dey, S. Das, M.K. Dutta, S.K. Mandal,
N. Majumder, T.K. De, S.K. Mukhopadhyay, T.K. Jana*
Department of Marine Science, University of Calcutta, 35, B. C. Road, Kolkata 700019, India
Abst ract
Here we show carbon stock is lower in the t ropical mangrove forest than in the terrestrial t ropical
forest and their annual increase exhibits faster turn over than the t ropical forest . Variable for
above ground biomass are in decreasing order of importance, breast height diameter (d), height
(H) and wood density ( ). The above ground biomass (AGB) and live below ground biomass
(LBGB) held different biomass (39.93 ± 14.05 t C ha−1 versus 9.61 ± 3.37 t C ha−1). Carbon
accrual to live biomass (4.71–6.54 Mg C ha−1 a−1) is more than offset by losses from litter fall
(4.85 Mg C ha−1 a−1), and carbon sequest rat ion differs significant ly between live biomass
(1.69 Mg C ha−1 a−1) and sediment (0.012 Mg C ha−1 a−1). Growth specific analyses of taxon
density suggest that changes in resource availability and environmental const rains could be the
cause of the annual increase in carbon stocks in the Sundarbans mangrove forest in cont rast to the
disturbance – recovery hypotheses
Citation: Ray, R., et al. (2011), Carbon sequestration and annual increase of carbon stock in a mangrove forest, Atmospheric Environment, doi:10.1016/j.atmosenv.2011.04.074