© 2019 IJRAR March 2019, Volume 6, Issue 1 www.ijrar.org (E-ISSN 23481269, P- ISSN 2349-5138) IJRAR19J3084 International Journal of Research and Analytical Reviews (IJRAR) www.ijrar.org 1287 DISTRIBUTION OF ORGANIC CARBON IN MANGROVE SOIL OF SUNDARBANS Samimul Islam *1 , Arpan Mitra 2 , Abhisek Saha 3 , Sufia Zaman 4 , Abhijit Mitra 4 *1,3,4 Department of Oceanography, Techno India University, West Bengal, Kolkata 700090, India. 2 A. Mitra & Company, 231 Rash Behari, Kolkata 700019, India. 4 Department of Marine Science, University of Calcutta, Kolkata 700019, India. Abstract Organic Carbon (OC) levels were monitored in four stations of Indian Sundarbans during June 2017. The level of organic carbon in soil differs significantly with stations. The order is Diamond harbour > Kachuberia > Banstala > Sagar South. This variation may be attributed to a large extent by mangrove biomass and diversity, forest age, the degree of tidal exchange and sedimentation of suspended matter. Also anthropogenic activities like fish landing, tourism and shrimp farms contribute appreciable amount of organic load in the selected stations. Keywords – Organic carbon, Indian Sundarbans, spatial variation I.NTRODUCTION Climate change is caused directly or indirectly by human activity that alters the composition of the global atmosphere and which is observed over comparable time periods in addition to natural climate variability [1]. Atmospheric concentration of carbon dioxide has increased from a pre-industrial value of 280 parts per million (ppm) to current levels of 387 ppm. This is the highest level in 650,000 years and is expected to double pre-industrial levels during this century, which could raise global temperatures 2 to 5 0 C over the next hundred years. Despite efforts to stabilize greenhouse gas concentrations by some countries, global warming will continue as a result of climate system inertia [2]. The impacts of climate change are readily apparent around the planet. Retreating glaciers and extreme precipitation events cause flooding in some areas while elsewhere water bodies are evaporating from the heat. Tropical diseases are spreading as hurricanes become stronger and more destructive. Since last few decades atmospheric concentrations of carbon dioxide have increased in a sustained way [3]. This has led to study the capacity of carbon sequestration in forests and other terrestrial and wetland ecosystems. Most of the studies are related to forest ecosystems and crops, and there is not enough information on carbon sequestration potential of wetland soil. Wetlands provide several important ecosystem services, among which carbon sequestration is most crucial. The reservoirs of soil organic carbon can act as sources or sinks of atmospheric carbon dioxide, depending on land use practices, climate, texture and topography [4-7]. Wetlands cover about 5% of the terrestrial surface and are important carbon sinks containing 40% of soil organic carbon at global level [8]. Estuarine wetlands have a capacity of carbon sequestration per unit area of approximately one order of magnitude greater than other systems of wetlands [9] and store carbon with a minimum emission of greenhouse gases due to inhibition of methanogenesis because of sulfate [10]. On this background it is extremely important to assess the organic carbon pool of intertidal mudflats of the famous mangrove ecosystem of Indian Sundarbans, which together with Bangladesh Sundarbans constitutes the world’s largest brackish water wetland. II.MATERIALS AND METHODS a) Study area The Sundarban mangrove ecosystem covering about one million ha in the deltaic complex of the Rivers Ganga, Brahmaputra and Meghna is shared between Bangladesh (62%) and India (38%) and is the world’s largest coastal wetland. Enormous load of sediments carried by the rivers contribute to its expansion and dynamics. Some 34 species of true mangroves thrive in this deltaic lobe [11]. We conducted survey at Kachuberia (station 1), Diamond Harbour (station 2), Banstala (station 3) and Sagar South (station 4) in the Indian Sundarbans region during June, 2017 and station selection was primarily based on anthropogenic activities and mangrove richness (Table 1). b) Sampling of soil Sampling areas of 10 m × 5 m were considered for each station. Care was taken to collect the surface samples within the same distance from the estuarine edge, tidal creeks and the same micro-topography. Under such conditions, spatial variability of external parameters such as tidal amplitude and frequency of inundation [12], inputs of material from the adjacent Bay/estuary and soil granulometry and salinity [13-14] are minimal. Soil samples from surface zone were collected. The uppermost 0.01m, which frequently includes debris and freshly fallen litter, was not used in this study. In the laboratory, the collected samples were carefully sieved and homogenized to remove roots and other plant and animal debris prior to oven-drying to constant weight at 60 0 C.