Physico-Chemical and Heavy Metals in the Groundwater Samples Collected from Arsenic Endemic Areas of Shuklaganj (Unnao)

Abstract

Hu man health is greatly affected by exposure to arsenic through drinking water. Arsenic is a carcinogen and its consumption can negatively affect the gastrointestinal tract, card io-vascular and central nervous systems. World Health Organisation (WHO) and US Environ mental Protection Agency have set the maximu m acceptable level of arsenic in drin king water as 10µg/L. Attempts have been made to determine and establish a database on the drinking water quality of Shuklaganj area with part icular emphasis on the physico-chemical characteristics and levels of heavy metals in the water samp les. The physico-chemical parameters determined were pH, hardness, alkalin ity, conductivity, TDS, salinity and ch loride content. The samples were collected in premonsoon and postmonsoon of Shuklaganj area. The pH of all the samples varied fro m 7.0 to 8.5 in both premonsoon and postmonsoon period. Hardness during in premonsoon varied fro m 180-212mg/ L and in postmonsoon varied fro m 140-210 mg/ l. Alkalinity varied fro m 84-112mg/ L in premonsoon and 60-128 mg/ L in postmosoon. However conductivity was quite high and it ranged from 320-2140 µs/cm in premonsoon and 358-1944µs/cm during postmonsoon. The TDS ranged fro m 181-1019 mg/l in premonsoon samples and 163-1102mg/l in postmonsoon. Salinity varied fro m 0.0-1.0 ppt in premonsoon and 0.0-1.3 ppt in postmonsoon. Chloride content varied fro m to 12.1-36.4 in premonsoon and 8.08-44.5 mg/ L in potmonsoon. The p icture of heavy metals and arsenic present in the water collected during premonsoon and postmonsoon periods were also determined. However, in premonsoon samples Cr, Cd and Ni were absent in most of the samples. It was noticed that Cd and Ni content was almost absent in the samples collected during postmonsoon season. Copper varied fro m 0.0 to 0.0178 mg/ L during premonsoon and 0.0002 to 0.0098mg/ L during postmonsoon. Zinc content varied fro m 0.0 to 3.26 in p remonsoon period and fro m 0.0-3.6 mg/L in postmonsoon period. Iron varied fro m 0.0 to 17.99 mg/ L in pre monsoon and varied fro m 0.0692 to 12.53 in postmonsoon samples. Manganese varied fro m 0.0 to 0.4454 mg/ L in premonsoon samples and 0.0018- 4.74 mg/ L in premonsoon samples. Arsenic in premonsoon season varied fro m 0-250 ppb and fro m 0-250 ppb in postmonsoon. It is s een that with increase in pH above 8.5, Arsenic desorbs from the o xide surfaces, thereby increasing concentration of Arsenic in solution. It is suggested that the most desirable and significant mechanism for the groundwater Arsenic problems is due to o xidising conditions and desorption of Arsenic fro m Arsenic contaminated sediments at high pH.