Abstract
The objectives of the present study were (1) to quantify the vertical distribution of the sediment bulk density (SBD), the sediment organic carbon (SOC) concentration; and the SOC density in the five northern lakes of Egypt (Bardawil, Manzala, Burullus, Edku and Mariut); (2) to estimate the carbon sequestration rate (CSR) and carbon sequestration potential (CSP) of these lakes; and (3) to establish a baseline data on SOC pools for future studies on SOC dynamics. Our hypothesis was that each of the abovementioned parameters varied among the five lakes. The mean SBD of Lake Bardawil was the highest, while that of Lake Manzala was the lowest. The mean SOC concentration of Lake Mariut was the highest, while that of Lake Edku was the lowest. We developed a negative exponential function between SBD and SOC concentration for each of the five lakes, where SBD increased and SOC concentration decreased with sediment depth. Considering the entire sediment profile (0-30 cm), the mean SOC density of Lake Mariut was the highest, while that of Lake Edku was the lowest. Significant differences in SOC pools were found among the five lakes, with the highest value obtained in Lake Mariut and the lowest in lakes Edku and Manzala. Based on the area of the five northern lakes of Egypt and their CSR, the CSP ranged from 0.95 Gg C yr(-1) in Lake Bardawil to 7.79 Gg C yr(-1) in Lake Manzala. Thus, it is necessary to protect and restore these lakes for carbon sequestration, as well as other ecosystem services that currently lack effective protection.