the evaluation of underground water recourses' boron concentration and variation pattern

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.