Occurrence and Geochemistry of Arsenic in Groundwater of Punjab, Northwest India

Abstract

Arsenic (As) is a deadly poison at high concentrations. It is mysterious in the sense that people are exposed to it most of the time through drinking groundwater, fortunately at much lower concentrations than the deadly levels, and usually without knowing it. Arsenic content in alluvial aquifers of Punjab varied from 3.5 to 688 mg L 21 . Arsenic status of groundwater is classified into low (,10 mg L 21 ), moderate (!10 to ,25 mg L 21 ), high (!25 to ,50 mg L 21 ), and very high (.50 mg L 21 ). In zone I, the concentration of As in groundwater varied from 3.5 to 42 mg L 21 with a mean value of 23.4 mg L 21 . On the basis of these limits, only 8% of samples were low, whereas 51 and 41% of the total samples collected from this region fall in the moderate and high As categories. The concentration of As in groundwater of zone II varied from 9.8 to 42.5 mg L 21 with a mean value of 24.1 mg L 21 . Arsenic concentration in the alluvial aquifers of the central plain of zone II is 2 and 52% in the low and moderate limits. In this region, 46% of groundwater sites contain high As concentrations. Arsenic concentrations in the aridic southwestern parts are significantly different from other two provinces. The As concentration ranged from 11.4 to 688 mg L 21 with average value of 76.8 mg L 21 . Eleven percent of the aquifers of the southwestern region of zone III are in the moderate category, 54% in the high, and 35% in the very high. According to safe As limits (,10 mg L 21 ), only 3 and 1% of the groundwater samples collected from zones I and II were fit for dinking purposes with respect to As content. In the aridic southwest, zone III, all water samples contained As concentrations greater than the safe limits and thus are not suitable for drinking purposes. The presence of elevated As concentrations in groundwater are generally due to the results of natural occurrences of As in the aquifer materials. The concentration of other competitive oxyanions in waters such as phosphate, sulfate, and borate also depressed the adsorption of As on the sorption sites of aquifer materials and thereby eventually elevate the As concentration in groundwaters. In groundwater of alluvial aquifers of Punjab, released from sulfide oxidation and oxyhydroxide of iron, elevated (.10 mg L 21 ) concentrations of As were widespread because of high pH (.8.0) and higher concentrations of phosphate, borate, sulfate, and hydroxyl anions. It is conclusively evident that geochemical conditions, such as pH, oxidation -reduction, associated or competing ions, and evaporative environments have significant effects on As concentration in groundwater. These conditions influence how much As is dissolved or precipitated into the water and how much is bound to the aquifer materials or the solid particles in water.

Arsenic content in ground and canal waters of Punjab, North-West India

“…However, it is important to mention here that these water samples were taken from Zone I and II which fulfill all the parameters suitable for good quality of water set by public health department since the arsenic content is not included in their tests. Hundal et al (2007) reported that the As concentration ranged from 11.4 to 688 ppb with average value of 76.8 ppb. In the aridic southwest, zone III, all water samples contained As concentrations much greater than the safe limit and thus were not suitable for drinking purposes.…”

“…Arsenic in ground water is largely the result of minerals dissolving from weathered rocks and soils. The underground waters contain elevated arsenic concentration, which are usually above the WHO (1996) permissible safe limits of 10 ppb (Hundal et al 2007). The problem is more severe at several sites in south-western districts of Punjab where the arsenic concentration exceeded more than 20 to 30 folds of the WHO safe limit.…”

Assessment of groundwater quality for drinking and irrigation purposes using hydrochemical studies in Malwa region, southwestern part of Punjab, India

“…According to Central Ground Water Board (2007), the groundwater in Bathinda is alkaline in nature, moderately to highly saline and contains high concentration of fluoride. Hundal et al (2007) reported arsenic concentrations greater than the safe limits in water samples from southwest zone of Punjab. Recently, there has been an alarming increase in the number of cancer cases in southwestern districts of Punjab.…”

“…Mean arsenic concentrations (10.19 lg/L) found in our study were higher than the arsenic concentrations reported previously in Bathinda, (Sharma 2012) and Amritsar (Hundal et al 2008), but less than the concentrations reported by Sidhu et al 2014 in southwestern region of Punjab. The elevated levels of arsenic in the study area may be due to its evaporative environment since the climate of this region is arid which can lead to more loss of water by evaporation than its gain by rainfall (Hundal et al 2007). Arsenic contamination is also strongly associated with high concentrations of iron, phosphate, and ammonium ions, and anthropogenic activities such as excessive groundwater withdrawal for agricultural irrigation (Kumar et al 2010).…”

Geospatial modelling for groundwater quality mapping: a case study of Rupnagar district, Punjab, India

“…Geochemical conditions, such as pH, oxidation-reduction, associated or competing ions, and evaporative environments, have significant effects on arsenic concentration in ground water (Hundal, et al, 2007). The research and studies indicated that sand and clay deposited by river is generally rich in iron and arsenic and the highest arsenic concentration zone exits below 40 meters.…”