Investigation of Runoff Heavy Metals Seasonal Changes in Bojnoord Urban Watershed

Due to the urban expansion, preparing of comprehensive and detailed information, is an unavoidable necessity for urban watershed systems and also its dominant conditions in hydrological cycle to gain an integrated urban watershed management. The urban runoff pollution caused by heavy metals is the major types of pollutions in surface runoff which may cause serious health risks for biosphere and also urban watersheds. This article examines the changes in runoff quality and the amount of heavy metals such as lead, zinc and copper in Bojnoord urban watershed in two reaches of autumn and spring seasons. For this reason 52 samples were collected for the mentioned period. After preparing the samples, using atomic absorption, the amount of heavy metals were measured in terms of Pbb. The results showed that the reducing trend of these metals is as Zn>Cu>Pb and the maximum concentration of lead, zinc and copper is related to the autumn season. The location of high concentrations is in residential and commercial areas and for the samples taken from the runoff pathways and drainage network (FB2). The Pearson correlation test results showed that there is a high positive correlation between lead and copper in the autumn (R=0.954) and also between lead and zinc in the spring (R=0.641). This correlation is certified by using factor analysis and Varimax rotation.