SEDIMENT PHOSPHORUS FORMS AND LEVELS OF TWO GANGETIC FLOODPLAIN WETLANDS IN INDIA

SEDIMENT LEVEL IN FLOODPLAIN WETLANDS

Abstract

Eutrophication in the present era is one of the major ecological problems. Phosphorus is an important and limiting nutrient which act a significant role in universal biogeochemical cycles. The phosphorus released from sediments can considerably impact the nutrient budgets of wetlands. So, a study was carried out to characterise the sediment phosphorus loading in two flood plain wetlands of lower Gangetic plain. The present study was conducted during February 2018 to January 2019 across three seasons (Pre Monsoon, Monsoon and Post Monsoon) in two floodplain wetlands, namely Chhara Ganga beel (open wetland) and Kalo Baur beel (closed wetland), West Bengal, India. Sediment samples were proceed for different phosphorous fractionation determination. The result revealed that wetland sediment samples contained total P in the ranges of 1039-2647 mg Kg-1 (mean 1865± 33.22 mg Kg-1) in open wetland and 1173-2476 mg Kg-1 (mean 1835 ± 89 mg Kg-1) in closed wetland. Exchangeable P or available P was of low level, varied from 0.26- 0.64 mg Kg-1 (mean 0.47 ± 0.07 mg Kg-1) in open wetland and 0.20-0.35 mg Kg-1 (mean 0.27 ± 0.02 mg Kg-1) in closed wetland. Calcium phosphorous (Ca P) was the dominant form among inorganic phosphorus analyzed and contributed 14.69 % and 15.94 % of total P in open and closed wetland, respectively. Available P, iron P, and organic P were observed to be higher in the open wetland. The sequence of different inorganic P fractions in both the wetland were: Ca-P > Fe-P > Al-P > available-P. High intensity of organic carbon was found in closed wetland. This study detected higher levels of available P, Fe P, and organic P in open wetland while Al P and Ca P in the closed wetland.