Effect Of Drilling Waste On Soil Quality At Opukushi Community In Delta State

ABSTRACT 

The effect of drilling waste on soil quality was studied at Opukushi Oil field dumpsite in Delta state. The period of sampling and analysis was between June and September 2010. Soil samples from the dump sites and the control site were physicochemical analyzed using Gas Chromatography, Atomic Absorption Spectrophotometer (AAS). Laboratory analysis were conducted according to standard methods. Descriptive statistical analysis was used to obtain range, means, standard errors, as well as graphical illustration of the variables. The test of homogeneity of variance in means of the variables spetially was explored using the one way ANOVA and further structure detection made with means plots. The interrelationships between the parameters were explored with the Pearson product moment correlation coefficient (r). Clay varied between 10.20 – 13.20 (11.84  0.40)%, Silt varied between 70.00 – 78.40 (73.70  1.22)%, sand varied between 11.10 – 17.00 (22.77  0.10)%, pore size varied between 26.20 – 38.90 (33.20  1.80)%, K varied between 0.06 – 1.60 (1.04  0.24) meqK, pH varied between 5.00 – 5.80 (5.30  0.11) and PAHs varied between negligible and 290.12 (125.00  38.80)mg/kg. The nutrients (PO43- and NO3-) varied from 9.45 – 18.40 (12.84  1.25) and 11.10 – 22.10 (15.23  1.54)mg/kg, respectively. While the trace metals (Pb, Cr and Ba) varied between 19.00 – 50.18 (30.01  4.17), 15.20 – 35.25 (26.00  2.73) and 63.15 – 140.10 (98.50  9.23)mg/kg, respectively. There was significant spatial inequality [F(16.05) > Fcrit (3.93)] at P < 0.05, especially in sampling sites. Several of the parameters correlated highly with each other at P < 0.05 and P < 0.01. The high concentrations of the PAHs and trace metals (Pb, Ba and Cr) coupled with the acidic soil and high sand composition could lead to infiltration of groundwater aquifers with surface contaminants. 

Key words: drilling waste, homogeneity of variance, spatial variation, correlations, means plots