The Evaluation of Underground Water Recourses' Boron Concentration and Variation Pattern

Abstract

Background: Rafsanjan -Noogh- Anar's plain (54°, 52′- 56°, 34′ longitudinally & 29°, 51′- 31°, 31′ latitudinally) is one of the Iran's plains located in sub- basin of Daranjir desert. Anar's plain is located at the lowest part of Rafsanjan -Noogh- Anar's plain. According to the geological and field studies of the area, the presence of west and east mounts and deposits re­sulting from evaporation in lower parts of the area are indicative of boron contamination of Anar underground water.

Methods: In the present study, 50 deep wells covering Anar plain were selected based on statistical methods. Boron con­centration in each well was measured by Azomethine- H method in the middle of each season, from 2003 to 2007.

Results: Comparing the obtained boron concentrations with WHO guidelines, Anar underground water is not safe for drink­ing (mean= 8.88 mg/L). In major part of the plain, the quality of water is not suitable for the growth of plants that are sensi­tive and unresisting to boron. Only in 17.1% of the samples boron concentration was between 0.7-3 mg/L that based on the guide­lines of Food and Agriculture Organization is suitable for some types of plants. Field studies about the area flora con­firm the obtained results too. Changes in the quality of underground water during the years of study, showed a worsening proc­ess over time.

Conclusion: To solve the problem, mixing of the water of low boron wells with high boron wells is recommended.