Refining aquifer heterogeneity and understanding groundwater recharge sources in an intensively exploited agrarian dominated region of the Ganga Plain

Densely populated region of Ganga Plain is facing aquifer vulnerability through waterborne pollutants and groundwater stress due to indiscriminate abstraction,causing environmental and socio-economic instabilities.To address long-term groundwater resilience,it is crucial to understand aquifer heterogeneity and connectivity,groundwater recharge sources,effects of groundwater abstraction etc.In this con-text,present study aims to understand factors responsible for vertical and spatial variability of groundwater chemistry and to identify groundwater recharge sources in an intensively exploited agrarian region of the Ganga Plain.Interpretation of chemometric,statistical,and isotopic analysis categorises the alluvial aquifer into zone 1(G1;ground surface to 100 m)and zone 2(G2;>100 m-210 m).The group G1 samples are characterized by a wide variation in hydrochemical species,noted with pockets of F-and NO3-rich groundwater,and fresh to more evolved water types,while group G2 groundwater is characterized by a sharp increase in freshwater types and limited variation in their isotopic and hydrochemical species.The G1 groundwater chemistry is governed by soil mineralogy,local anthropogenic inputs(SO42-,Cl-,and NO3-),and manifested by multiple recharge sources(local precipitation,river,canal water,pond).The G2 group is dominated by geogenic processes and mainly recharged by the local precipitation.Geospatial signatures confirm more evolved water type for group G1 in northwestern region,while fresh-water type covers the rest of the study area.Fluoride rich groundwater is attributed to sodic water under alkaline conditions and enrichedδ18O values emphasizing role of evaporation in F-mobilization from micas and amphiboles abundant in the soil.The findings provide insight into potential groundwater vulnerability towards inorganic contaminants,and ground water recharge sources.The outcome of this study will help to develop aquifer resilience towards indiscriminate groundwater extraction for agricultural practices and aim towards sustainable management strategies in a similar hydrogeological setting.

Hydrochemical evolution of groundwater in northwestern part of the Indo-Gangetic Basin,India:A geochemical and isotopic approach

The present study aims to understand the hydrochemical evolution of groundwater in the Ghaggar River Basin,representing a zone of excessive abstraction of groundwater in the northwestern Indo-Gangetic Basin.The study comprises a regional scale and high-resolution sampling of groundwater during preand post-monsoon seasons of 2013 and their analyses for major ions,δ^(18)O,δ^(2)H,and 3 H.Variation in hydrochemical and isotopic data is found both in spatial and vertical scales.The significant vertical variation of TDS,NO_(3)and K^(+)allowed the classification of the aquifer system into two major groups:shallow(depth<80 m bgl)and deep(depth>80 m bgl).The depthwise variations ofδ^(18)O andδ^(2)H support this categorization of the aquifers.The Ca-HCO_(3)and Ca-Mg-Na-HCO_(3)water facies with higher values of 3 H in the proximal part of the basin characterize recharge areas under humid conditions.The dominance of Mg-Na-HCO_(3)and Na-HCO_(3)facies in shallow and deep aquifers in central part of the basin,illustrate the intermediate to advanced stages of hydrochemical evolution in the system.Dominance of brackish Ca-Mg-Cl-SO_(4)and Na-Cl-SO_(4)water types in the discharge areas is due to the prevailing geological conditions and anthropogenic activities.Geochemical modelling supports the reverse cation exchange and mixing during lateral and vertical flows,weathering of silicate minerals,dissolution of crustal salts,and evaporative enrichment are the natural processes governing the evolution of groundwater chemistry along the flowpaths.The developed process-based conceptual model will aid in the formulation of a suitable plan for groundwater resource management in the region.

Characterization of atmospheric aerosol (PM10 and PM2.5) from a medium sized city in S?o Paulo state,Brazil

Air pollution causes deleterious effects on human health with aerosols being among the most polluting agents.The objective of this work is the characterization of the PM2.5 and PM10 aerosol mass in the atmosphere.The methods of analysis include WD-XRF and EDS.Data were correlated with meteorological information and air mass trajectories(model HYSPLIT)by multivariate analysis.A morphological structural analysis was also carried out to identify the probable sources of atmospheric aerosols in the city of Sao Jose do Rio Preto,Brazil.The mean mass concentration values obtained were 24.54 μg/m^3 for PM10,above the WHO annual standard value of 20 μg/m^3 and 10.88 μg/m^3 for PM2.5 whose WHO recommended limit is10 μg/m^3.WD-XRF analysis of the samples revealed Si and Al as major components of the coarse fraction.In the fine fraction,the major elements were Al and S.The SEM-FEG characterization allowed identifying the morphology of the particles in agglomerates,ellipsoids and filaments in the PM10,besides spherical in the PM2.5.The analysis by EDS corroborated WD-XRF results,identifying the crustal elements,aluminosilicates and elements of anthropogenic origin in the coarse fraction.For the fine fraction crustal elements were also identified;aluminosilicates,black carbon and spherical particles(C and O) originating from combustion processes were predominant.The use of multivariate analysis to correlate air mass trajectories with the results of the morpho-structural characterization of the particulate matter allowed confirmation of the complex composition of the particles resulting from the combination of both local and long-distance sources.