Determination of Total Arsenic in Water Resources: A Case Study of Rivash in Kashmar City

Abstract

Background: Arsenic is one of the hazardous elements, and drinking arsenic-rich water could cause various diseases such as cancer. The standard by the world health organization (WHO) and Iran for arsenic in drinking water is 10 µg L-1 and 50 µg L-1, respectively. Objectives: This study was conducted to survey the arsenic concentration in the rural water resources of Rivash, Kashmar. Materials and Methods: In this cross-sectional study, 60 samples were gathered from 10 sampling stations (all water supplies in Rivash, Kashmar) from April to June 2013. All the water supplies were groundwater (i.e. wells and springs). The sampling and preservation of the samples were performed according to the standard methods, and assessment was conducted using the Vapor Generation Accessory (VGA) method. Some factors such as pH, total dissolved solids (TDS), and electrical conductivity (EC) were tested to survey their relationship with the arsenic concentration. The data were analyzed using SPSS and the statistical tests of one-sample t-test and Mann-Whitney at a significance level of 0.05. The arsenic level was thereafter compared with the national and international standards. Results: The average arsenic levels in stations A, B, C, D, E, F, G, H, I, and J were 1.53 ± 1.03, 1.30 ± 1.07, 10.55 ± 3.83, 11.21 ± 5.01, 10.57 ± 3.68, 2.34 ± 0.73, 3.22 ± 0.58, 9.89 ± 3.57, 10.48 ± 5.07, and 2.23 ± 0.53µg L-1, respectively. The arsenic concentration levels were higher than the WHO guideline in 5 stations and lower in the others, but in none of the stations did the levels exceed the national standard. The difference between the arsenic levels and the national standard was statistically significant (P < 0.001). The difference between the arsenic levels in 50% of the stations and the WHO standard was significant (P < 0.001). There were no significant relationships between the arsenic level and TDS, EC, temperature, salinity, and residual chlorine, with the exception of pH. Conclusions: Given the high levels of arsenic in the Rivash water sources, it is essential that a plan be devised to replace the current supply with safe drinking water. Moreover, these water resources should be monitored regularly regarding the risk of contamination with arsenic.