Emerging nitrate contamination in groundwater: Changing phase in a fast-growing state of India.

The consumption of nitrate-contaminated groundwater is often associated with potential health risks, particularly in children. This study aimed to assess the hydrochemistry and nitrate contamination in groundwater of Kerala state, India for the years 2010 and 2018 and evaluate the potential human health risks due to nitrate exposure in adults, and children through oral ingestion and dermal contact pathways. Nitrate-contaminated zones were identified by spatial mapping of nitrate concentration based on groundwater quality data of 324 wells. Groundwater is typically acidic to slightly alkaline, and the electrical conductivity (EC) varied from 33 to 1180 µS/cm in 2010 and 34.6-2500 mg/L in 2018 indicating a noticeable increase over the years. Most samples fall within low salt enrichment category. The nitrate concentration in groundwater varied from 0 to 173 mg/L with a mean of 15.4 mg/L during 2010 and 0 to 244 with a mean of 20.3 mg/L during 2018. Though nitrate concentrations show uneven spatial distributions due to both natural and anthropogenic sources, the spatial clustering of higher concentrations remains almost same in both periods. In 2010, non-carcinogenic risk, as measured by Health Index Total (HITotal) values in groundwater for the investigated region, ranged from 0.005 to 4.170 (mean of 0.349) for males, 0.005 to 4.928 (mean of 0.413) for females, and 0.008 to 7.243 (mean of 0.607) for children, while in 2018, the corresponding values varied from 0.001 to 5.881 (mean of 0.501) for males, 0.002 to 6.950 (mean of 0.592) for females, and 0.003 to 10.215 (mean of 0.870) for children, indicating a substantial increase in risk, for females and children. Greater health risk is observed in children during both the periods. The findings emphasize the need for proper water quality management, especially in regions with higher vulnerability to nitrate pollution, to safeguard human health and well-being.

An integrated groundwater resource management approach for sustainable development in a tropical river basin, southern India.

Evaluation of aquifer potential is essential, as the potable water demand has increased globally over the last few decades. The present study delineated different zones of groundwater potential and groundwater quality of the Kallada River basin (KRB) in southern India, using geo-environmental and hydrogeochemical parameters, respectively. Geo-environmental variables considered include relative relief, land use/land cover, drainage density, slope angle, geomorphology, and geology, while hydrogeochemical parameters include pH, electrical conductivity (EC), Cl-, Fe3+, and Al3+ concentrations. Analytical hierarchy process (AHP) was used for categorizing groundwater potential and quality zones. Nearly 50% of KRB is categorized as very high and high groundwater potential zones, occupying the western and midland regions. The central and west-central parts of KRB are characterized by excellent groundwater quality zones, while the eastern and western parts are characterized by good and poor groundwater quality zones, respectively. By integrating the groundwater potential and groundwater quality, sustainable groundwater management is observed to be necessary at about 54% of the basin, where site-specific groundwater management structures such as percolation ponds, injection wells, and roof water harvesting have been proposed using a rule-based approach. This integrated groundwater potential-groundwater quality approach helps policymakers to implement the most suitable management strategies with maximum performance.

Spatial analysis of chronic obstructive pulmonary disease and its risk factors in an urban area of Trivandrum, Kerala, India.

Background: Chronic obstructive pulmonary disease (COPD) is the second leading cause of death in India. The objective of this study was to map COPD cases and its risk factors and to determine the association between them using geographic information system (GIS) in a semi-urban area of Trivandrum, South India. Materials and Methods: This community-based cross-sectional, descriptive study (n = 494) was conducted in a subcenter area of a primary health center. Location was mapped and COPD population screener questionnaire was administered to all the study subjects enrolled by census method. Lifetime firewood exposure (person-hours) and tobacco smoking were enquired and distance from road was mapped using portable differential global positioning system. The association with COPD was assessed by kriging and hotspot analysis using ArcGIS software. Results: The prevalence of COPD (6.5%) was comparable to national prevalence estimates. Spatial maps showed COPD case clustering in areas with higher firewood exposure, greater smoking exposure, and in households with closer proximity to local roads. A particular high-risk cluster was obtained which had a significant association with all the risk factors. Conclusion: GIS technology is useful in identification of spatial clustering of COPD cases and its environmental risk factors, making it an important tool for targeted interventions for COPD.

Understanding the hydrogeochemical processes and physical parameters controlling the groundwater chemistry of a tropical river basin, South India.

Detailed investigation on hydrogeochemistry of hard rock terrains is important to identify the major geochemical processes and the source of ionic constituents in groundwater. The present study is carried out to understand the hydrogeochemistry of groundwater resources and the major hydrogeochemical processes, controlling the concentration of major ions in groundwater in the Kallada River Basin (KRB), South India. About 166 groundwater samples were collected from KRB during pre- and post-monsoon of 2016 for hydrogeochemical analysis. Most of the groundwater samples in KRB were within permissible limits of drinking water quality. The dominant groundwater types during pre-monsoon were Ca2+-Mg2+-Cl- which was changed to Na+-Cl- during post-monsoon. This is supported by the inverse relationship of depth of wells and change in EC during pre- and post-monsoon periods. Rock-water interaction processes such as reverse ion exchange and silicate weathering are major geochemical processes responsible for the hydrogeochemical signatures of KRB. The shallower wells (< 10 m) show strongest relation with the water types Na+-HCO3- and Ca2+-Mg2+-Cl- which have been changed to Na+-Cl- and Ca2+-Mg2+-HCO3- during post-monsoon. However, in deeper wells, Na+-Cl- is the dominant type of water during both seasons. The hierarchical cluster analysis displays different hydrogeochemical associations representing diverse physicochemical parameters both spatially and temporally. This study could shed light on diverse hydrogeochemical processes which are responsible for the hydrogeochemistry in KRB. Major hydrogeochemical processes in the Kallada River Basi.

Spatial analysis of hypothyroidism and ground water pH in an Urban Area of Kerala using the geographic information system.

Hypothyroidism is a disease assuming increasing relevance. The causative role of acidic nature of drinking water has not yet been investigated in Kerala. We attempted to determine the spatial association between the occurrence of self-reported hypothyroidism and pH of ground water using the geographic information system. The cross-sectional study was conducted among 1649 individuals residing in the subcenter area in urban Trivandrum. Self-reported hypothyroidism was obtained by the interview. Differential Global Positioning System was used to record the location of each house and its drinking water source. PH of 50 open-well water samples was estimated. The prevalence of self-reported hypothyroidism was 4.24%. Maps depicting pH distribution and occurrence of hypothyroidism were prepared. Most of the areas had acidic ground water. Geo-statistical analysis revealed the occurrence of statistically significant clustering of hypothyroid individuals in areas having acidic ground water. The study brings out possible linkage between hypothyroidism and acidic water intake necessitating detailed epidemiological investigations for drawing more robust associations.

Time series analysis to monitor and assess water resources: a moving average approach.

An understanding of the behavior of the groundwater body and its long-term trends are essential for making any management decision in a given watershed. Geostatistical methods can effectively be used to derive the long-term trends of the groundwater body. Here an attempt has been made to find out the long-term trends of the water table fluctuations of a river basin through a time series approach. The method was found to be useful for demarcating the zones of discharge and of recharge of an aquifer. The recharge of the aquifer is attributed to the return flow from applied irrigation. In the study area, farmers mainly depend on borewells for water and water is pumped from the deep aquifer indiscriminately. The recharge of the shallow aquifer implies excessive pumping of the deep aquifer. Necessary steps have to be taken immediately at appropriate levels to control the irrational pumping of deep aquifer groundwater, which is needed as a future water source. The study emphasizes the use of geostatistics for the better management of water resources and sustainable development of the area.

The utility of multivariate statistical techniques in hydrogeochemical studies: an example from Karnataka, India.

Quality of groundwater is controlled by many factors amongst which the interaction of river water with adjacent groundwater and mixing/non-mixing of different types of groundwater may be important. An attempt has been made to study these processes using multivariate statistical techniques such as factor and cluster analyses. The Nethravathi catchment (India) which is a tropical river basin draining the Precambrian crystalline province of peninsular India, has been selected for this study. Hydrogeochemical data for 56 groundwater samples were subjected to Q- and R- mode factor and cluster analysis. R-mode analysis reveals the inter-relations among the variables studied and the Q-mode analysis reveals the inter-relations among the samples studied. The R-mode factor analysis shows that Na and Cl with HCO3 account for most of the electrical conductivity and total dissolved solids of the groundwater. The 'single dominance' nature of the majority of the factors in the R-mode analysis indicates non-mixing or partial mixing of different types of groundwater. Both Q-mode factor and Q-mode cluster analyses shows that there is an exchange between the river water and the adjacent groundwater.