Global water demand has far exceeded the total available water resources which in turn have put a serious concern on food security. Changes in the land use and land cover scenario and rapid population growth are putting unavoidable stress over the water resources of the nation. The Indian aquifer system is facing an acute crisis due to the unscientific abstraction of groundwater for agricultural, industrial and domestic sector by the 1.3 billion growing population. To investigate the groundwater degradation, 20 wells from a river basin of West Bengal have been selected to study their seasonal groundwater level trend using Mann-Kendall test statistics from 1996 to 2018 where 60% of the wells are showing a decline in water level particularly in post-monsoon season. These wells are mainly located near the agricultural land where extraction of groundwater from submersible pumping wells is extensive as observed from socioeconomic survey. Agglomerated hierarchical cluster analysis has been executed to classify the wells based on their magnitude of fluctuation. The wells have been classified in four clusters where cluster I consists most of the wells about 15 numbers whose fluctuation ranged between 1.8 and 4.33 m below groundwater level (mbgl). Finally, Standard Groundwater Level Index has been applied to understand the groundwater drought years. Well locations like Simlapal, Bheduasol and Neradeul have a higher frequency of drought years. The recharge potential of the wells is now decreasing day by day. Such kind of studies is required and will help the stakeholders to focus on sustainable management of this valuable water resource.

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This paper focuses on determining an efficient and simple method to remove arsenic from groundwater. Arsenic is a naturally occurring element widely distributed in the earth's crust. Arsenic is very toxic when found in large quantities in drinking water. This report documents the selected treatment method and laboratory experimentation of arsenic removal from drinking water in small water delivery systems and domestic water systems. The objective is to expand upon research of new and existing arsenic removal technologies or promote a new, alternative process. Several treatment technologies have been considered to perform this function, but cost and reliability concerns prompted the decision to analyze small-scale, community-based filtration units, specifically. Based upon initial test data, the use of dual treatment method comprising of oxidation-coagulation-filtration and adsorption by activated alumina has proven to be more economic having more capacity and superior reliability as compared to other arsenic removal processes using various other media.

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The decrease and degradation of the tropical forests affect not only the production of timber but also the global environment in a large scale. The ability of soil to sustain and its supply of nutrients to a growing forest are controlled by a complex of biogeochemical processes. The purpose of the present study aims to assess the degraded forest fringe areas, to promote plantations of various types and to evaluate their impacts on the soil nutrients and carbon content accumulation. The soil organic carbon (SOC) and nutrient content were evaluated and compared between plantations of mixed native species (MNS), some native tree species as Shorea robusta, Dalbergia sissoo, Dendrocalamus spp., certain agro-forestry species and some exotic varieties. The impacts of the plantations on the SOC and the nutrients were firstly analyzed through comprehensive chemical analyses and the results were compared with the soil samples collected prior to plantation forestry. Significant changes were observed in SOC content, in nutrients, and in amounts of exchangeable cations. Soil carbon levels were highest under the MNS, Dendrocalamus and Tectona grandis stands and lowest under D. sissoo and Terminalia arjuna. Total N showed highest levels under Dendrocalamus and Pongamia pinnata and significantly higher in stands of native species; lowest total N level was observed in D. sissoo plantations. The C/N ratios of the soil varied between 9.2 and 13.5 among the exchangeable cations. Ca 2þ recorded the maximum levels and Na þ showed the lowest levels.

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Temperature drives the major physico-chemical and biological actions in inland water bodies. The higher the water temperature, the greater the biogeochemical activity influenced by the environmental intrinsic and extrinsic parameters. Temperature also controls the dynamics of sustainability of various aquatic organisms that live in lakes and reservoirs, though higher life forms, such as fish, insects, zooplankton, phytoplankton, and other aquatic species all have a recommended temperature variety. The increase in water temperature due to the increase in atmospheric air temperature results in lake water column stratification and the dissolved oxygen level variation in aquatic systems are greatly affected. The vertical distributions of dissolved oxygen in the water column are highly dependent due to change in vertical temperature gradient. In the present paper, an effort has been made to investigate the impact of temperature stratification on dissolved oxygen variability in the Rudrasagar, a natural lake in western Tripura. The changes in dissolved oxygen distribution in this natural lake will give us an idea of regional lake health condition and will also establish the need of further large scale research concerning the development of a biophysical-coupled model.   Keywords: Thermal stratification, Dissolved Oxygen, Thermocline, Rudrasagar Lake, Hypolimnion

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