Biological Sciences Department, Faculty of Science, Niger Delta University, Wilberforce Island, Amassoma, Bayelsa State, Nigeria.
The study was carried out to establish the presence of soils capable of triggering acidification upon disturbance during development and construction activities. Two sets of samples were collected in close proximity within the study area, one set was intact (un-drained) under mangrove cover, while the other an abandoned dredged soil (drained and exposed) from selected rivers in the Niger Delta including, Benin River, Escravos River, Warri River, Gbaraun Creek and Sego Creek. The samples were incubated at field capacity for ten weeks and pH measurements were made weekly. Moist incubation/aged pH was carried out using the probe method. Results of in situ pH measurements show that the intact soil under mangrove vegetation cover (PASS) has pH in the neutral range (7.0 – 7.3), while the dredged sediment (AASS) pH is in the order of 3.7 – 3.9, which are classified as extremely acid. During the ten week incubation, the difference in the pH measurements of the two soils narrowed, with the PASS having pH in the range of 1.4 – 3.4 and the AASS in the order of 1.5, which were classified as ultra acids. Because the decrease in pH after incubation is more than 0.5, it indicates the potential for acidification when disturbed. The study concludes that the disturbance of mangrove soil through dredging and drainage during project execution and other development purposes could cause acidification, which can be indicated using moist/aged pH measurement.
AASS, Acidification, Acidithiobacillus sp., aged pH, dredging, indicators, moist incubation pH, Niger Delta, oil exploration, PASS, pyrite, wetlands
