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B. M. J. K. Balasooriya et al.
VF5 had a moderate positive loading on nitrate and arsenic, chromium. Nitrogenous fertilizers, organic manures, human and animal wastes and the effluent from
industrial activities are the major sources of nitrate in groundwater (Villholth and
Rajasooriyar 2010, Jiang et al. 2009, Noshardi and Ghafourian 2016). Arsenic and
nitrate occupy same factor in the factor analysis. However, arsenic concentrations
exceeding 10 ug/l [Sri Lankan standard for drinking water (SLS 2013)] were found
in groundwater wells associated with the soil type of ‘sandy regosols on recent beach
and dune sands’ only. Coincidently, these areas are agricultural areas, and farmers
use high amount of nitrogen fertilizers for papaya, onion, vegetables and tobacco
(Specifically in Kalpitiya peninsula) cultivations in the coastal belt. Further, nitrate
pollution in different levels was observed in all agricultural areas in Sri Lanka, while
some of them observed to exceed 50 mg/l, Sri Lankan standard for drinking water
(SLS 2013). For example, Anuradhapura and Badulla districts located in the middle
of the country also showed high nitrate concentrations at some locations, but arsenic
concentrations were less than 10 ug/l Sri Lankan standard for drinking water (SLS
2013) in Badulla or Anuradhapura district. Therefore, arsenic has no relationship
with nitrate, which is strong enough to indicate that arsenic may come from fertilizer. However, there are reports that arsenic, chromium and other heavy metals
may enter into the groundwater through agrochemicals and retain in groundwater
since sandy soils are poor in adsorption. However, clayey soils in other agricultural
areas may adsorb arsenic hence cannot observe in groundwater in dissolved forms
(Wongsasuluk et al. 2014, Liu et al. 2006). Correlation of chromium with nitrate may
also explain the agrochemical usage (Liu et al. 2003).
The sources of lead in groundwater are soil, air, used lead products and the use
of lead pipes and roofing material (WHO 2011). Dissolution of residues of vehicle
emission in the groundwater through precipitation may be the way of addition of lead
into water bodies and to increase the concentration of lead in groundwater (Leung and
Jiao 2006). According to the Annual Performance and Accounts Report of Ministry of
Environment, Sri Lanka (2001), vehicle gas emission is very high in Colombo, Galle
and Kandy districts, in which higher concentrations of lead in groundwater were
observed. The groundwater table is higher in above districts, since they locate in wet
zone of Sri Lanka, hence storm water runoff may easily filtrate to the groundwater
(Villholth and Rajasooriyar 2010). Hence, lead may enter into groundwater through
vehicle emission, and this hypothesize is supported by the higher values of lead in
wet zone and occupying separate factor; VF6.
5.5 Conclusion
In this study, spatial variations in groundwater quality in Sri Lanka were evaluated
using multivariate statistical analysis techniques. Sampled groundwater wells (n =
1262) were clustered into two different clusters based on the attributes of the groundwater quality parameters. The average concentrations of fluoride, EC, pH, chloride,
B. M. J. K. Balasooriya et al.
VF5 had a moderate positive loading on nitrate and arsenic, chromium. Nitrogenous fertilizers, organic manures, human and animal wastes and the effluent from
industrial activities are the major sources of nitrate in groundwater (Villholth and
Rajasooriyar 2010, Jiang et al. 2009, Noshardi and Ghafourian 2016). Arsenic and
nitrate occupy same factor in the factor analysis. However, arsenic concentrations
exceeding 10 ug/l [Sri Lankan standard for drinking water (SLS 2013)] were found
in groundwater wells associated with the soil type of ‘sandy regosols on recent beach
and dune sands’ only. Coincidently, these areas are agricultural areas, and farmers
use high amount of nitrogen fertilizers for papaya, onion, vegetables and tobacco
(Specifically in Kalpitiya peninsula) cultivations in the coastal belt. Further, nitrate
pollution in different levels was observed in all agricultural areas in Sri Lanka, while
some of them observed to exceed 50 mg/l, Sri Lankan standard for drinking water
(SLS 2013). For example, Anuradhapura and Badulla districts located in the middle
of the country also showed high nitrate concentrations at some locations, but arsenic
concentrations were less than 10 ug/l Sri Lankan standard for drinking water (SLS
2013) in Badulla or Anuradhapura district. Therefore, arsenic has no relationship
with nitrate, which is strong enough to indicate that arsenic may come from fertilizer. However, there are reports that arsenic, chromium and other heavy metals
may enter into the groundwater through agrochemicals and retain in groundwater
since sandy soils are poor in adsorption. However, clayey soils in other agricultural
areas may adsorb arsenic hence cannot observe in groundwater in dissolved forms
(Wongsasuluk et al. 2014, Liu et al. 2006). Correlation of chromium with nitrate may
also explain the agrochemical usage (Liu et al. 2003).
The sources of lead in groundwater are soil, air, used lead products and the use
of lead pipes and roofing material (WHO 2011). Dissolution of residues of vehicle
emission in the groundwater through precipitation may be the way of addition of lead
into water bodies and to increase the concentration of lead in groundwater (Leung and
Jiao 2006). According to the Annual Performance and Accounts Report of Ministry of
Environment, Sri Lanka (2001), vehicle gas emission is very high in Colombo, Galle
and Kandy districts, in which higher concentrations of lead in groundwater were
observed. The groundwater table is higher in above districts, since they locate in wet
zone of Sri Lanka, hence storm water runoff may easily filtrate to the groundwater
(Villholth and Rajasooriyar 2010). Hence, lead may enter into groundwater through
vehicle emission, and this hypothesize is supported by the higher values of lead in
wet zone and occupying separate factor; VF6.
5.5 Conclusion
In this study, spatial variations in groundwater quality in Sri Lanka were evaluated
using multivariate statistical analysis techniques. Sampled groundwater wells (n =
1262) were clustered into two different clusters based on the attributes of the groundwater quality parameters. The average concentrations of fluoride, EC, pH, chloride,