Green Algae as Bioindicators of Heavy Metal Pollution in Wadi Hanifah Stream, Riyadh, Saudi Arabia

Abstract

Anthropogenic activities around the main stream of Wadi Hanifah may lead to a considerable increase in the heavy metal loading of the stream. The two filamentous green algae Enteromorpha intestinalis (Linnaeus) Nees and Cladophora glomerata (Linnaeus) Kutzing were collected from three sites along the valley and used to determine the heavy metal concentrations in the main stream. The dried algal samples were digested using appropriate acids and the concentrations of manganese (Mn), copper (Cu), Zinc (Zn), Arsenic (As), cadmium (Cd) and lead (Pb) were measured in the aliquot samples using Inductively Coupled plasma-Optical Emission spectrometer (ICP-OES). High burden of manganese, copper and arsenic were detected at all sites indicating a high degree of pollution by these elements. The levels of zinc, cadmium and lead were within the expected limits for uncontaminated areas. E. intestinalis could be used as an excellent indicator for manganese, zinc and arsenic pollution, whereas C. glomerata may be used as an excellent indicator for copper, cadmium and lead pollution in this area. The stream runs through the city of Riyadh and serious efforts should be considered to decrease the heavy metal levels in this fragile and valuable habitat.