Carbon storage of Mangrove Sediments in Kibani, Eastern Niger Delta, Nigeria: Implications on the Environment

Abstract

The amount of carbon stored in the mangrove sediments in Kibani area of Eastern Niger Delta was quantified. The objectives were to determine the sediment bulk density (SBD) and organic carbon concentration (%C), and estimate the amount of organic carbon stock in the top 100-cm depth of mangrove sediments and its carbon dioxide equivalent (CO2 e). A total of 312 sediment samples were collected from 24 different sampling points at seven locations. An open-cylindrical gouge auger of 100-cm length and 5-cm diameter was designed and fabricated for the purpose of sediment sampling. Field measurement, laboratory analysis, data presentation and result presentation followed the Guidelines for Forest Carbon Measurement, Monitoring and Reporting. The sediment type has a major control on the distribution of organic carbon. The lithology is a typical of mangrove forest and included peat and clay with pockets of sands. Sediment bulk density (SBD) and %C ranged from 0.95 g/cm3 to 1.97 g/cm3 (mean = 1.30 g/cm3 ) and 0.9 % to 33.6 % (mean = 12.48 %) respectively. Carbon stocks ranged from 24.12 ± 15.18 Mg C ha-1 to 3245.76 ± 15.18 Mg C ha-1 (mean value = 39.80 Mg ha-1) while CO2 e ranged 88.52 ± 15.18 Mg CO2 ha-1 to 11,911.94 ± 15.18 Mg CO2 ha-1 (mean = 2,348.07 ± 15.18 Mg CO2 ha-1). The total carbon stock of the study area was estimated at 947.78 ± 55.64 Gg C, equivalent to 3,478.36 ± 55.64 Gg CO2 . The study revealed that 732,595.71 ± 55.64 Mg of carbon dioxide is stored in the sediments. This amount could either be removed or released to the atmosphere through forest management practices and/or degradation to exacerbate climate change and /or mitigate it. It is recommended that Niger Delta region of Nigeria should be protected against all anthropogenic-related degradation which influence the amount of carbon storage.