Jyoti Prakash Deka

Source and seasonal variation in the major ion chemistry of two eastern Himalayan high altitude lakes, India

A chemical survey of two high-altitudes lakes, i.e., Tsokyo Tso and Sella, was conducted during pre-monsoon (May) and post-monsoon (November) 2011. Lake water is found to be pure with very low EC values even lesser than rainwater. This shows where lake water receives most of its contribution. A comprehensive and systematic study on the seasonal pattern of major ions (Cl−, PO43−, HCO3−, NO3−, SO42−, Na+, K+, Ca2+, Mg2+, and SiO2) was carried out to understand the geochemical processes controlling water quality. There was marked seasonal variation observed for almost all ions. Factor analysis identifies geochemical controls, snow melting, and evaporative enrichment as main controlling factor. The partial pressure of CO2 (pCO2) value has increased in the post-monsoon probably due to higher atmospheric CO2 during winter. Overall, factor analysis identified processes like geochemical control, snowmelt water input, and evaporative enrichment in the pre-monsoon, atmospheric input and dilution of ions due to rainfall, microbial activities, and accumulation of weathered material lake system in the post-monsoon as governing processes switching among themselves in different seasons. HYSPILT back trajectory model was used to trace the source of long-range transport of pollutant. Results show for both the lakes that air arriving to the vicinity of the lake has an origin from the southeast direction during pre-monsoon and the mid-Gangetic plain during post-monsoon season, respectively. The results show that both the studied lakes have significant impacts of long-range transport of air pollutants rather than local interferences. Long-term monitoring of the fluctuation in key parameters can further verify the findings of this study.

Suitability of conventional and membrane bioreactor system in textile mill effluent treatment

AbstractEffluents from the industries contaminate surface water, soil and groundwater due to the presence of soluble solids, suspended solids, organic matter, heavy metals and toxic constituents. This necessitates treatment of the discharged wastewater and determination of effluent quality. The situation is very alarming for Tirupur due to textile industries effluent, affecting water consumption pattern around the whole area that generates high stress on groundwater resources as well as agricultural productivity. The present study is based on the general characterization of the quality of effluent before and after installation of conventional effluent treatment plants (CETPs) and membrane bioreactor (MBR) treatment systems. The performance evaluation of CETPs and MBR systems in textile mill effluent treatment was carried out in terms of effluent quality and treatment efficiency. The findings revealed that the CETPs were efficient in removal of total dissolved solids, bicarbonate () total major cations and...

Tracing phosphorous distributions in the surficial sediments of two eastern Himalayan high altitude lakes through sequential extraction, multivariate and HYSPLIT back trajectory analyses

Phosphorous (P) fractionation of the surficial sediment of high altitude lakes (HAL) i.e. P.T.Tso and Sella lakes of Arunachal Pradesh State, India were studied with an objective to investigate the phosphorus availability in the environment, nutrient status of the lake and the role of climate change. Moreover, the variation in phosphorous fraction was investigated through mineralogical studies like grain size analysis and X-ray diffraction. The findings revealed that the surficial sediment of lakes are least influenced by anthropogenic sources, since a slight increase in each of the P-Fractions was observed from year 2011 to 2012, except organic P. Loosely sorbed exchangeable phosphorous was found to be slightly high which was due to difference in atmospheric precipitation, which is one of the strong factors in high altitude regions. Decrease in organic fraction of P indicated that lakes became more oligotrophic in nature. Mineralogical investigation shows that illite-montmorillonite and montmorillonite are the main minerals in Sella Lake, whereas montmorillonite and graphite are main minerals in P.T.Tso lake. Factor analysis of seasonal data of P fractionation in surface sediments, along with physical parameters of Sella Lake water indicates three factors for the 2011 data principle factors are pH, EC, oxide-bound and organic P. Factor analysis of P.T.Tso lake water indicates three factors for the 2011 data with principle factors are adsorbed P and authigenic P, pH, oxide-bound P. This study shows that except organic fractions all other fractions are increasing in the following year. It implies that even at such remote high altitude locations P characteristics are changing year to year which sought for further investigation and enables HALs to show the early impacts of climate change related changes. A clear influence of long range transported air pollutants has been found through HYSPLIT back trajectory models which needs to be substantiated through long-term monitoring.

Understanding the Seasonal Dynamics of the Groundwater Hydrogeochemistry in National Capital Territory (NCT) of India Through Geochemical Modelling

A geochemical assessment of seasonal dynamics in the groundwater chemistry of the National Capital Territory (NCT), Delhi, was attempted through geochemical modelling, mineral precipitation sequences with rainfall and water evaporation cycle. Saturation indices calculated using PHREEQC indicated that the degree of water–rock equilibrium changes significantly from pre-monsoon to post-monsoon. The schematic model of SI change with water table fluctuation showed that during monsoon, as rainwater percolates through the soil, partial pressure of CO2 becomes higher than that of the atmospheric value and led to the formation of more carbonic acid that react with the carbonate minerals to produce

Hydrogeochemical zonation for groundwater management in the area with diversified geological and land-use setup

{{{\text{HCO}}_{3}^{-} }}

Effect of river proximity on the arsenic and fluoride distribution in the aquifers of the Brahmaputra Floodplains, Assam, Northeast India

HCO3-, Mg2+ and Ca2+. The thermodynamic stability relationships of water chemistry in the Na, K, Ca and Mg silicate systems showed that for the samples with higher EC equilibrium between clay and primary minerals is not likely to be the main processes controlling variation in the groundwater chemistry. Chloro-alkaline indices (CAI) are positive when the groundwater level is high and become negative with the lowering of water level, i.e. when water level is high, reverse ion exchange is dominant. In case of pre-monsoon season, lower and negative value of CAI-1 and CAI-2 indicates dominance of ion exchange process and increases dissolved solid concentration in groundwater. The conceptual geochemical model depicted that water table fluctuation resulting from heavy pumping/withdrawal and recharge in association with the variation in DO,

Groundwater appraisal of Dhekiajuli, Assam, India: an insight of agricultural suitability and arsenic enrichment

{{{\text{HCO}}_{3}^{-} }}