Ultraviolet radiation and bromide as limiting factors in eutrophication processes in semiarid climate zones

Abstract

Eutrophication studies were conducted at four selected sites of surface water bodies in Jorden: viz. King Abdullal Canal in the Jordan Valley, Mujib dam, Wadi Rajil dam in the eastern desert of Jordan, and Muwaqqar dams in the eastern highlands of Jordan. The factors responsible for eutrophication processes are high NO3, PO4, and K concentrations in addition to sunlight, high temperature, and micronutrients, such as, Zn and Fe. When these dam reservoirs and canals were examined they were found to have all the suitable conditions but no eutrophication. Water reservoirs in the desert areas of Jordan seemed not to develop eutrophication owing to the high UV radiation lasting for about 330 days a year with average sunlight duration of 9.5 h a day. UV radiation was found to be the limiting factor in eutrophication processes. Other water bodies, especially in the Jordan Valley area contain high concentrations of bromide, of more than 500 μg/l. Bromide is a strong oxidant and seems to be responsible for the non-development of eutrophication processes, although all other factors which enhance eutrophication were available.