Contamination of Arsenic in Groundwater …
23
Table 5 Correlation between iron, manganese and arsenic (n = 36)
Parameters
Fe
Mn
As
Fe
1.000
Mn
0.423 **
1.000
As
0.621 **
0.510 **
1.000
**significant value at p < 0.01
by alterations in depth to water or pumping rate, are determining factors in arsenic
variability [14, 17].
4.1 Correlation Between Iron, Manganese and Arsenic
The relationship between of Fe, Mn and As in tube wells/wells was analyzed by
Pearson’s correlation (Table 5). Strong positive correlations of As were observed
with iron and manganese (r = 0.621, p < 0.01; r = 0.423, p < 0.01), which is
attributed to common geographic origin of these metals. A similar study reported
that arsenic and iron have positive correlation [22]. Naturally occurring As that is
absorbed to iron oxyhydroxides is released when the iron oxyhydroxide is reduced
as anoxic conditions developed during burial of the sediments [4].
5 Conclusion
Groundwater is the major source for drinking, household and irrigation purposes
in the Tarai areas of Nepal. The demand for groundwater is accelerating due to
fast population growth and industrial activities. From this study, out of total tube
wells/well, about 50% of tube wells exceeded permissible guideline value of WHO
(10 ppb), whereas 16.6% tube wells exceeded permissible value (50 ppb) of Nepal
Interim Standard. In addition to that, dug wells provide arsenic-safer drinking water
compared to tube wells. Since contaminated water is regularly used for drinking,
cooking and other household purposes, it can be said that risk of As poisoning
is high in the study areas. The conditions of As poisoning are related to minerals
solubility in aquifer (iron and manganese), pH, redox conditions, etc.
Acknowledgements This work was supported by REACH, Nepal. We would also like to acknowledge Mr. Chandra Nath Kayastha for his valuable time helping to find out dug wells/tube wells and
also to collect the water samples.
23
Table 5 Correlation between iron, manganese and arsenic (n = 36)
Parameters
Fe
Mn
As
Fe
1.000
Mn
0.423 **
1.000
As
0.621 **
0.510 **
1.000
**significant value at p < 0.01
by alterations in depth to water or pumping rate, are determining factors in arsenic
variability [14, 17].
4.1 Correlation Between Iron, Manganese and Arsenic
The relationship between of Fe, Mn and As in tube wells/wells was analyzed by
Pearson’s correlation (Table 5). Strong positive correlations of As were observed
with iron and manganese (r = 0.621, p < 0.01; r = 0.423, p < 0.01), which is
attributed to common geographic origin of these metals. A similar study reported
that arsenic and iron have positive correlation [22]. Naturally occurring As that is
absorbed to iron oxyhydroxides is released when the iron oxyhydroxide is reduced
as anoxic conditions developed during burial of the sediments [4].
5 Conclusion
Groundwater is the major source for drinking, household and irrigation purposes
in the Tarai areas of Nepal. The demand for groundwater is accelerating due to
fast population growth and industrial activities. From this study, out of total tube
wells/well, about 50% of tube wells exceeded permissible guideline value of WHO
(10 ppb), whereas 16.6% tube wells exceeded permissible value (50 ppb) of Nepal
Interim Standard. In addition to that, dug wells provide arsenic-safer drinking water
compared to tube wells. Since contaminated water is regularly used for drinking,
cooking and other household purposes, it can be said that risk of As poisoning
is high in the study areas. The conditions of As poisoning are related to minerals
solubility in aquifer (iron and manganese), pH, redox conditions, etc.
Acknowledgements This work was supported by REACH, Nepal. We would also like to acknowledge Mr. Chandra Nath Kayastha for his valuable time helping to find out dug wells/tube wells and
also to collect the water samples.