Evaluation of carbon sequestration in the sediment of polluted and non-polluted locations of mangroves

Abstract

The government of Saudi Arabia launched the Jazan Economic City (JEC) at Baish near Jezan city in 2006. However, there is a concern that immense industrial and urban development at JEC will seriously impact the coastal mangrove habitats. To explore the related environmental stresses on mangrove forests near JEC, the present study was conducted at three locations characterized as one close to an industrial port, one close to shrimp aqua-cultures, and one further from immediate human impacts: (1) to assess the vertical distribution of the sediment bulk density (SBD), sediment organic carbon (SOC) concentration, and SOC density in two polluted mangrove (Avicen-nia marina) locations in comparison with a non-polluted location along the southern Red Sea coast of Saudi Arabia; and (2) to estimate the SOC pool and carbon sequestration rate (CSR) of these locations. We hypothesise that each of the above-mentioned parameters varied between the polluted and non-polluted locations. In total, 400 sediment samples were collected and analysed to determine the SBD, the SOC concentration, density and pool, and the CSR, to reveal significant variation between the polluted and non-polluted mangrove locations in terms of the total mean values of the SBD, the SOC concentration, density and pool, and the CSR. An increase in SBD with a decrease in concentration and density of SOC is evident with an increase in depth at both polluted and non-polluted mangrove locations. The SOC pool at the non-polluted location (11.5 kg C m−2) is significantly (p < 0.05) larger than the SOC pool at the polluted locations (9.9 kg C m−2). Similarly, the average CSR at the non-polluted location (5.1 g C m−2 yr−1) is significantly (p < 0.001) greater than the average CRS at the polluted locations (4.4 g C m−2 yr−1). Thus, there is an urgent need to implement climate mitigation projects in order to manage and restore the mangrove ecosystems along the coastal regions of Saudi Arabia, and protect and conserve the present SOC pools.