Javad Shahraki - Regional Water Organization of Sistan and Baluchistan, Zahedan, Iran
Mohammad Amin Khandan Barani - Regional Water Organization of Sistan and Baluchistan, Zahedan, Iran
Seyed Mahmood Pahlavan Hashemi - Regional Water Organization of Sistan and Baluchistan, Zahedan, Iran
Homayun Rezaei - Regional Water Organization of Sistan and Baluchistan, Zahedan, Iran

Streambed-sediment samples were collected in the Karvandar River Basin in the Sistan and Balouchestan province to determine the occurrence and distribution of lead in urban/rural and nonurban/rural areas of the basin. During fall ۲۰۱۲ and fall ۲۰۱۳, streambed sediment was collected at ۳۰ sites, and the samples were analyzed for lead. The ranges in concentrations of lead in streambed sediments at urban/rural sites were orders of magnitude higher than the ranges of concentrations at nonurban/rural sites. Concentrations of lead at sites with different geologic settingswere considered to be not statistically significant (t = ۰.۰۷۹, p = ۰.۹۳); however, concentrations of lead at these sites can be compared without substantial effects of natural geologic characteristics. Lead in streambed sediment was at concentrations that can adversely affect the aquatic biota in ۴۸ percent of the urban/rural sites in the basin for both particle-size fractions. Lead concentrations in the m fraction were higher than the total particle-size fraction. Distribution patterns for lead indicate that grossly contamination (>SEL) does not exist throughout the entire drainage basin. A comparison between the sites close to the source and sites downstream indicated that the pattern of increasing concentrations was observed for lead with increasing distance from the source.

Lead, Streambed Sediments, Karvandar River Basin, IRAN, Concentration, Urban/Rural Sites,Nonurban/Rural Sites, Particle-Size Fractions