Heavy Metal Concentration and Physicochemical Parameters in Soil and Plants near Unengineered Dumpsites in Port Harcourt, Nigeria

Abstract

Cross sectional study was conducted around two unengineered dumpsites in Port Harcourt, Nigeria on heavy metal concentrations and physicochemical parameters in soil and plants. Physicochemical parameters studied include pH, Total Dissolved Solids (TDS), Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Electrical Conductivity (EC), Nitrite ion, Phosphate ion, Sulphate ion, Chloride ion and heavy metals (Cd, Pb, Zn, Fe, and Cu). The result shows that edible plants were observed to have recorded one variety of metal or the other; and a relatively higher concentration of metals were found in the soil than in plant which indicates possible gradual movement of metals from the soil samples into the plants. Chloride ion concentration was negligible in all edible plants, but traces of other anions were recorded in both plants. Both dumpsites have contamination factor (CF) ranging from low to very highly polluted for different metals. Contamination degree (CD) at the dumpsites showed that both sites have very high degree of contamination. Pollution Load Index (PLI) of 4.64 in S1 (Soil sample from Choba dumpsite) and 4.19 in S2 (Soil sample from Ada-George dumpsite) show that there is progressive deterioration of the two sites. Index of geoaccumulation (Igeo) values obtained show that Zn was the only metal that did not enrich the soil with Zero (0) values (S1 = -0.04, and S2 = -2.00); which indicate that it originated from natural processes or crustal materials alone, and not from anthropogenic sources. Other metal concentrations ranged from unpolluted to moderately polluted and to extremely polluted. Bioaccumulation Factor (BAF) showed that all the dumpsites are excluders and are not effective accumulators of metals and anions from the soil into the plants. Urgent attention has to be given to the dumpsites to prevent further degradation of the soil and possible bioaccumulation of metals in edible plants.