Surface water processes in coping with anthropogenic impact in a coastal Eastern Mediterranean region

Abstract

Rivers are progressively being exposed to increased anthropogenic pollution stresses that are undermining their designated-uses and affecting sensitive coastal areas. In this study, three adjacent Eastern Mediterranean coastal rivers Ibrahim, Kaleb and Beirut were evaluated. Water quality samples were collected in dry and wet season from different sampling sites along the river from the source to the outlet that represent a gradient of increased urbanization. The spatio-temporal variability of the physio-chemical properties, heavy metals (Zn, Pb, Cu, Cr and Cd) and organic matter (DOC) were statistically analyzed to better understand the contribution of point and non-point pollution sources. The three rivers (Beirut, Kaleb and Ibrahim) show a similar behavior in calcium and carbonate alkalinity due to the carbonate mineral weathering effect so they are of calcium bicarbonate type due to their calcareous geological nature. The speciation of anions was affected by temporal variation. Moreover, it is obvious that Beirut River has a different behavioral characteristic where the water is of a sulfate type water with a preferable metal-OM complexation mainly with lead, zinc and copper whereas Kaleb and Ibrahim are considered to be of a nitrate phosphate type with a preferable metal inorganic complexation specially copper that has a consistent behavior in both type of waters. This difference is attributed to the urbanization effect highly impacting Beirut River.