Monsoonal Influence on Evapotranspiration of the Tropical Mangrove Forest in Northeast India
Dipnarayan Ganguly, Raghab Ray, Natasha Majumder, Chumki Chowdhury,
Tapan Kumar Jana
American Journal of Climate Change, 2014, 3, 232-244

Abstract

Evapotranspiration (ET) is an important part of the water cycle. This study reports on the monsoonal influence on the temporal variation in evapotranspiration of an extremely water conservative and salinity stressed tropical mangrove forest at the land-ocean boundary of northeast coast of India. The magnitude and dynamics of evapotranspiration (ET) exhibited seasonality dominated by monsoon and evaporation rate was greater (0.055 ± 0.015 g∙m−2∙s−1) during the monsoon than in pre-monsoon (0.049 ± 0.018 g∙m−2∙s−1) and post-monsoon (0.044 ± 0.012 g∙m−2∙s−1). Seasonal difference in evapotranpiration was mostly due to fluctuation of canopy resistance, which was the minimum during monsoon when relative humidity was greater than in the dry season (pre- and post-monsoon) and deficiency of water supply (ET ≈ ETeq) was minimum. Evapotranspiration in the Sundarban mangrove ecosystem is the predominant biophysical processes that recycles 67.7% of total precipitation annually to the atmosphere, and has significant monsoonal influence.

Keywords

Canopy Resistance, Evapotranspiration, Hydrological Cycle, India, Mangrove Forest, Monsoonal Cycle

Accumulation, transport and toxicity of arsenic in the Sundarbans mangrove, India

Geoderma 354 (2019) 113891

Accumulation, transport and toxicity of arsenic in the Sundarbans
mangrove, India

Sanjay Kumar Mandala, b, Raghab Ray c,  Aridane G. Gonzálezd, Oleg S. Pokrovskye, f,g,
Vasileios Mavromatise,e, Tapan Kumar Jana, a
a Department of Marine Science, The University of Calcutta, Kolkata, India
b Dept. of Chemistry, The University of Calcutta, Sundarban Hazi Desarat College, Pathankhali, South 24 Parganas, India
c Atmosphere and Ocean Research Institute (AORI), The University of Tokyo, Kashiwa, Japan
d Instituto de Oceanografía y Cambio Global, Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
e GET (Géosciences Environnement Toulouse) UMR 5563 CNRS, Toulouse, France
f BIO-GEO-CLIM Laboratory, Tomsk State University, Tomsk, Russia
g N. Laverov Federal Center for Integrated Arctic Research, Russian Academy of Sciences, Arkhangelsk, Russia

A R T I C L E I N F O

Handling Editor: Daniel Said-Pullicino
Keywords: Trace metal, Sequestration, Biomass, Mangrove, Bay of Bengal

A B S T R A C T

Arsenic (As), a toxic element is a concern for the habitants in and around the coastal areas of West Bengal (India) where world's largest Sundarbans mangrove is situated. Little is known about the potential of these mangroves in storing As within their biomass and transporting to the Bay of Bengal. A comprehensive yearly data of above ground and below ground biomass (AGB, BGB), and exchange fluxes like litter fall, plant uptake, sedimentary diffusion/advection, and suspended particle deposition were used in a box model for constructing As budget for the Sundarbans mangroves. About 80% of total As was stored in AGB while As stock in sediment was several hundred times higher than in the AGB and BGB indicating poor bioaccumulation and sequestration capacity of the mangroves, which was further supported by higher As loss though litterfall (16.8 μg As m−2 month−1) compared to gain through plant uptake (0.05 μg As m−2 month−1). About 65% of the river-discharged As exported to the Bay of Bengal, the rest amounting to 67.2×103 kg yr−1 remained in the mangrove estuaries. Although ecotoxicological indexes confirmed low As pollution impact in the Sundarbans, mass budget revealed net As addition in the estuarine ecosystem (67.2 Mg As yr−1), mainly derived from natural and anthropogenic sources such as, contamination via atmospheric dust deposition. Overall reservoir-based mass budget showed weak As sequestration capacity by these mangroves. The approach developed for As in this study could be applied to other major metals to estimate metal sequestration and conservation potential by the Sundarbans mangroves.

State of rare earth elements in the sediment and their bioaccumulation by mangroves: a case study in pristine islands of Indian Sundarban

State of rare earth elements in the sediment and their bioaccumulation by mangroves: a case study in pristine islands of Indian Sundarban

Sanjay K. Mandal1,2 & Raghab Ray3,4 & Aridane G. González3,5 & Vasileios Mavromatis6 & Oleg S. Pokrovsky6,7,8 & Tapan K. Jana1
Received: 9 August 2018 /Accepted: 10 January 2019
# Springer-Verlag GmbH Germany, part of Springer Nature 2019

Abstract

The mangrove ecosystems are known to efficiently sequester trace metals both in sediments and plant biomass. However, less is known about the chemistry of rare earth elements (REE) in the coastal environments, especially in the world’s largest mangrove province, the Sundarban. Here, the concentration of REE in the sediment and plant organs of eight dominant mangrove species (mainly Avicennia sp.) in the Indian Sundarban was measured to assess REE sources, distribution, and bioaccumulation state. Results revealed that light REE (LREE) were more concentrated than
the heavy REE (HREE) (128–144 mg kg−1 and 12–15 mg kg−1, respectively) in the mangrove sediments, with a relatively weak positive europium anomaly (Eu/Eu* = 1.03–1.14) with respect to North American shale composite. The primary source of REE was most likely linked to aluminosilicate weathering of crustal materials, and the resultant increase in LREE in the detritus. Vertical distribution of REE in one of the long cores from Lothian Island was altered by mangrove root activity and dependent on various physicochemical properties in the sediment (e.g., Eh, pH, organic carbon, and phosphate). REE uptake by plants was higher in the below-ground parts than in the above-ground plant tissues (root = 3.3 mg kg−1, leaf + wood = 1.7 mg kg−1); however, their total concentration was much lower than in the sediment (149.5 mg kg−1). Species-specific variability in bioaccumulation factor and translocation factor was observed indicating different REE partitioning and varying degree of mangrove uptake efficiency. Total REE stock in plant (above + live below ground) was estimated to be 168 g ha−1 with LREE contributing ~ 90% of the stock. This study highlighted the efficiency of using REE as a biological proxy in determining the degree of bioaccumulation within the mangrove environment.

Keywords Rare earth elements (REE) . Bioaccumulation . Mangrove . Sundarban
Responsible editor: Philippe Garrigues
* Raghab Ray raghab.ray@gmail.com; raghab.ray@aori.u-tokyo.ac.jp
1 Department of Marine Science, Calcutta University, Kolkata 70019, India
2 Department of Chemistry, Sundarban HaziDesarat College, South 24 Parganas, Pathankhali 743611, India
3 LEMAR (Laboratoire des Sciences de l’Environnement Marin), UMR 6539, (CNRS-UBO-IRD- IFREMER), 29280 Plouzané, France
4 Department of Chemical Oceanography, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa 277-8564, Japan
5 Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria, ULPGC, 35017 Las Palmas de Gran Canaria, Spain
6 GET (Géosciences Environnement Toulouse) UMR 5563 CNRS, 31400 Toulouse, France
7 BIO-GEO-CLIM Laboratory, Tomsk State University, Tomsk, Russia 634050
8 N. Laverov Federal Center for Integrated Arctic Research, IEPS, Russian Academy of Sciences, Arkhangelsk, Russia 163000
Environmental Science and Pollution Researchhttps://doi.org/10.1007/s11356-019-04222-1