Hydrogeochemical characterisation and geospatial analysis of groundwater for drinking water quality in Ludhiana district of Punjab, India.

This study characterises the quality of groundwater for the Ludhiana district of Punjab, India by analysing water samples collected from 152 locations spread across 3767 km2. The samples were analysed for 18 parameters consisting of pH, EC, TDS, TA, TH, major anions and cations. The parameter values have been used to calculate the drinking water quality index of the study area which suggests that 2.6, 57.9, 32.9, 4 and 2.6% of the samples fall under the excellent, good, poor, very poor and unsuitable categories, respectively. The sequence of abundance for ions (in meq/l) as revealed from the laboratory tests is Na+ (37.1%) > Ca2+ (30.8%) > Mg2+ (29.1%) > K+ (2.8%) for cations and HCO3- (80%) > Cl¯ (8.9%) > CO32- (6.5%) > SO42- (3.9%) > NO3-, F-, PO43- (< 1%) for anions. The spatial variability of these parameters has been depicted through the use of interpolation maps. Evaluation of different ionic ratios indicates that carbonate weathering and silicate weathering are both significantly affecting the groundwater chemistry with a slight dominance of carbonate weathering. Also, the ion exchange process is taking place in the area as confirmed by CAI index values. In terms of saturation index, the groundwater is undersaturated with respect to halite, fluorite and sylvite, whereas it is supersaturated for calcite, dolomite and aragonite minerals. The principal components in PCA explained 75.4% of the total variance with 29.1 and 28.3% contributions from PC1 and PC2. Both of these components indicate towards the geogenic and anthropogenic influence on groundwater mineralization of the area. The analysis suggests that groundwater for the study area is suitable for drinking in most of the region expect in a few places. Such a study could be used to understand the current status of groundwater quality in the area, the results of which can be used to prevent further contamination and sustain the resource for the future.

A comprehensive review of groundwater vulnerability assessment using index-based, modelling, and coupling methods.

Groundwater has become increasingly vulnerable to quality degradation. An elaborate understanding of its flow, draft, recharge and pollutant transport processes needs to be developed to understand its risk to contamination. This paper has discussed different tools and methods that are used to map groundwater vulnerability around the world. To maintain the quality and impact of the study, rigorous search for relevant literature published in high impact scientific journals has been done, and the comprehensive information on groundwater vulnerability assessment methods being used, has been compiled. The GIS based overlay and index-based methods like DRASTIC, GALDIT, GOD, COP and PI takes into consideration various thematic layers, overlays them to calculate weighted index and identifies vulnerability classes. They have been criticised for the lack of numerical basis in their formulation. Therefore, over the years, many of the proposed indices have been modified to provide quantitative estimates of groundwater potential to degrade and deplete. However, where the data and software are not a constraint, the use of numerical based simulation models can be done for more elaborate and numerical based quantification of the vulnerability. These numerical models typically require extensive data and are exceedingly becoming more sophisticated with the introduction of new parameters. This study concludes that integrating the GIS with numerical models offers the advantage of data management and assists to spatially analyse the datasets. The difficulties that are associated with the differences between GIS and numerical model's data structures should be thoroughly understood, prior to coupling, to develop uniform conversion software.

HRCT evaluation of microtia: A retrospective study.

PURPOSE: To determine external, middle, and inner ear abnormalities on high-resolution computed tomography (HRCT) of temporal bone in patients with microtia and to predict anatomic external and middle ear anomalies as well as the degree of functional hearing impairment based on clinical grades of microtia. MATERIALS AND METHODS: It was a retrospective study conducted on Indian population. Fifty-two patients with microtia were evaluated for external, middle, and inner ear anomalies on HRCT of temporal bone. Clinical grading of microtia was done based on criteria proposed by Weerda et al. in 37 patients and degree of hearing loss was assessed using pure tone audiometry or brainstem-evoked response in 32 patients. Independent statistical correlations of clinical grades of micotia with both external and middle ear anomalies detected on HRCT and the degree of hearing loss were finally obtained. RESULTS: The external, middle, and inner ear anomalies were present in 93.1%, 74.5%, and 2.7% patients, respectively. Combined cartilaginous and bony external auditory canal atresia (EAC) was the most common anatomic abnormality in our group of microtia patients. Hypoplastic mesotympanum represented the commonest middle ear anomaly. The incidence of combined ossicular dysplasia and facial canal anomalies was lower as compared to other population groups; however, we recorded a greater incidence of cholesteatoma. Both these factors can have a substantial impact on outcome of patients planned for surgery. We found no significant association between grades of microtia and external or middle ear anomalies. Similarly, no significant association was found between lower grades of microtia (grade I and II) and degree of hearing loss. However, association between grade III microtia and degree of hearing loss was significant. A significant association between congenital cholesteatoma and degree of pneumatization of atretic plate and mastoid process not previously studied was also recorded in our study.