SUMMARIZED GEOCHEMICAL RESULT OF ANALYTICAL SAMPLES OF HEAVY ELEMENT CONCENTRATION 0F PB, ZN, CU, CD, AS AND NI IN THE STREAM SEDIMENTS FROM RIVER

The result of the analysis for Pb, Zn, Cu, Cd, As and Ni in the stream sediments from river Iyiokwu in Abakaliki and its environs is as shown in Table 2, table 3 shows the summarized geochemical result of the analytical samples of the heavy elements concentration. Bar chart was also used to explain the distribution of these elements.cal samples

Table: Summarized Geochemical Result of Analytical Samples of Heavy Element Concentration in River Iyiokwu in Abakaliki and its Environs in mg/kg

Table 4: Statistical analysis of various concentration of element in stream sediment in mg/kg

Table 5: Average abundance of the analysed heavy metals in the Earth’s Crust and Shale after Levinson (1971).

Element	Earth’s crust	Shale
Lead (Pb)	12.5	20
Zinc (Zn)	70	90
Copper (Cu)	55	50
Arsenic (As)	1.8	10
Cadmium (Cd)	0.15	0.3
Nickel (Ni)	75	80

 4.2.1 Lead (Pb)

            Around River Iyiokwu in Abakaliki and its environs, lead was evenly distributed in the stream sediments as shown in Table 3 with only 1 location showing deficiency (location 9). The mean concentration of each (Pb) is 4.17mg/kg (table 4), while the maximum concentration was 9.10mg/kg, with a minimum concentration of 0.3mg/kg. Its range was at 8.8mg/kg. From the analysis of the sample collected from the stream sediments, it shows that lead is below its toxic level. Magma fluid is the regular geological source of Pb which gives rise to Pb –Zn deposits in ore-bodies. Its low toxicity in the stream sediments may by contributed to the long distance of transportation and deposition.                                                 

                                             Sample locations

4.2.2 Zinc (Zn)

             In the study area, the maximum concentration of zinc was 40.9mg/kg and its minimum concentration at 10.7mg/kg (table 4). Zinc was evenly distributed in the stream sediments due to its existence with mobile element in the study area. It also has a mean concentration of 28.22mg/kg and a range of 30.2mg/kg. The evenly distribution of Zn shows high concentration in the derelict mines of Abakaliki (ministry of works quarry) and low in stream sediments far from the mine.

                                                 Sample locations

4.2.3 Copper (Cu)

            Copper was noticed to be below its tolerable level in normal soil which is 30mg/kg. Copper was almost evenly distributed in the stream sediments of river Iyiokwu with 2 sample locations showing deficiency in copper (locations 13 & 14).

            Its mean concentration is 6.82mg/kg. The maximum concentration of Cu was 17.7mg/kg (L11) and its minimum concentration was 0.4 mg/kg (L12). Copper being far below its tolerable level in normal soil may be as a result of its distance from the primary source of the deposit that contains copper.

                                              Sample locations                                                          

4.2.4 Cadmium

            Cadmium was not evenly distributed in the whole twenty sample locations collected for the analysis. Five (5) sample locations shows deficiency in cadmium after the analysis. Thus its total mean concentration is 3.98mg/kg. It has a maximum concentration of 12.2mg/kg (location 11) and a minimum concentration of 0.4mg/kg (L19). The concentration of cadmium in the stream sediments of River Iyiokwu is attributed to human activities and weathering of parent materials rich in cadmium such as black shale.

                                           Sample locations

4.2.5 Arsenic (As)

            Arsenic was not evenly dispersed in the stream sediments of river Iyiokwu in Abakaliki and its environs. Seven sample locations shows deficiency in Arsenic as regards to the analysis. Most of the concentration of As in most of the samples is below the detection limit of the analytical equipment. Its total mean concentration is 3.16mg/kg. It has a maximum concentration of 40mg/kgs (Location 6). Minimum concentration of 0.1mg/kgs (location 3). Its deficiency may be as a result of its distance from the source.

                                               Sample locations                      

Fig 11: Bar chart showing the distribution of arsenic in the different sample locations                      

4.2.6 Nickel (Ni)

            There was deficiency of nickel in 6 Locations (Locations 1, 3, 7, 12, 13, 14). Thus, It was not evenly dispersed. It has total mean concentration of 1.83mg/kg, its maximum concentration is 12.4mg/kg (Location 11) and a minimum concentration of 0.1mg/kg (Location 2).

                 

4.3 POLLUTION STATUS OF THE STREAM SEDIMENTS

In characterizi
ng the contamination level in stream sediments in Iyiokwu River, the approach described in the United States Environmental Protection Agency (USEPA), Mid-Atlantic Intergrated Assessment  (MAIA) for estuaries 1997-1998 Summary Report and the United States Geological Survey Water Resources Investigation Report 95-4267 was espoused. This was in line with the sediment quality guideline established by Long. et al. (1995). After reviewing nine elements that have ecological and biological effects on organisms, Effect Range Low (ERL) was defined as the lowest concentration of metals that produced adverse effects in 10% of organisms reviewed in the MAIA project. The Effect Range Median (ERM) designates the level at which 50% of the organisms studied reported harmful effects. Metals concentration in the sediments above ERM are likely to be very toxic. Table 6 below shows the ERL and ERM limits for metal contaminants in sediments.

Table 6: ERL and ERM limits for metals (USEPA-MAIA 1998)

Metals	ERL values	ERM values
Lead (Pb)	47	220
Zinc (Zn)	150	410
Copper (Cu)	34	270
Arsenic (As)	1.2	9.6
Cadmium (Cd)	8.2	70
Nickel (Ni)	21	52

            From table 6 above, the ERM for lead is 220mg, its total concentration in all sampled locations is below the ERM and ERL which is 47mg. Hence, lead concentration is below the toxic level. The ERM for zinc is 410, the highest concentration of zinc is 43.1mg/kg thus, its way below the toxic level. Also, ERM for copper is 270 and the highest concentration is 17.7 (Location 11) thus explains that the concentration of copper is below the toxic level.

Again, the ERM for arsenic, cadmium and nickel being 9.6, 70 and 52 respectively shows that they are way below the toxic level.

4.4 Geoaccumulation Index (Igeo)

            This is defined by the formular Igeo= log² Cn/1.5Bn, where Cn is the measured concentration of metals in pelitic sediment fraction and Bn is the geochemical background value (Average Shale) in the earth’s crust (see table 5). The constant 1.5 allows for natural fluctuations in the content of a given substance in the environment and very small anthropogenic influences. Table 7 below shows the classes of geoacumulation index.

Table 7: Classes Of The Geoacumulation Index.

Class	Value	Soil/sediment quality
0	Igeo<0	Practically uncontaminated
1	0	Uncontaminated to moderately contaminated
2	1	Moderately uncontaminated
3	2	Moderately contaminated-heavily contaminated
4	3	Heavily contaminated
5	4	Heavily contaminated-extremely contaminated
6	5	Extremely contaminated

Table 8: Showing the Geoacumulation Index of the Analysed Elements

s/n	Pb	Zn	Cu	As	Cd	Ni
1	0.042	0.054	0.006	0	0	0
2	0.014	0.059	0.007	0.090	0	0.0003
3	0.017	0.027	0.013	0.002	0.736	0
4	0.012	0.083	0.041	0.016	0.535	0.002
5	0.005	0.091	0.004	0	1.739	0.001
6	0.003	0.067	0.041	0.803	1.204	0.003
7	0.011	0.048	0.007	0	0.803	0
8	0.007	0.052	0.006	0	0	0.010
9	0	0.096	0.063	0.006	3.679	0.003
10	0.015	0.054	0.0514	0.010	0.870	0.002
11	0.012	0.083	0.071	0.014	8.160	0.031
12	0.056	0.048	0.002	0.018	0	0
13	0.067	0.024	0	0	0.344	0
14	0.066	0.047	0	0	0	0
15	0.074	0.057	0.009	0.008	2.341	0.002
16	0.091	0.077	0.004	0.014	3.612	0.0018
17	0.075	0.069	0.043	0.014	0.736	0.002
18	0.063	0.089	0.043	0.022	0	0.001
19	0.071	0.066	0.042	0.020	0.268	0.002
20	0.091	0.067	0.039	0	4.348	0.004

            Following the geoacumulation index from Table 8 above, it is deduced that five (5) of the heavy metals satisfy class 0 (practically uncontaminated) of Table 7 above (Classes of geoacumulation index) except cadmium. Cadmium was found to show extreme contamination with the highest value occurring at Sample Location 11 (Afikpo rd) at 8.160mg/kg. They all fall between Abakaliki metropolis due to pollution of drainage system and activities of the people within the metropolis.

4.5 Pearson Correlation

Table 9: Pearson Correlation Coefficient Of Analysed Elements

	Pb	Zn	Cu	As	Cd	Ni
Ni	-0.238	0.287	0.513	-0.011	0.760	1
Cd	-0.006	0.444	0.516	0.046	1
As	-0.273	0.061	0.163	1
Cu	-0.207	0.577	1
Zn	-0.139	1
Pb	1

From table 9 above, there is a fairly strong positive correlation between copper and zinc, copper and cadmium, copper and nickel. Whereas cadmium and zinc are weakly correlated. Cadmium and nickel showed the highest positive correlation with a value of  0.760

4.6 POLLUTION INDEX

            The pollution index is given by the formular = concentration in metal (mg/kg) divided by the ERM ( Effect Range Median). Table 10 below shows the pollution index for the analysed samples. Comparing the pollution index data and the analysed result data, it shows that all the samples has low or no level of toxicity.

Table 10: Pollution Index of the Analysed Elements

s/n	Pb	Zn	Cu	As	Cd	Ni
1	0.019	0.059	0.006	0	0	0
2	0.006	0.065	0.007	0.469	0	0.002
3	0.008	0.029	0.012	0.010	0.016	0
4	0.005	0.091	0.038	0.083	0.011	0.012
5	0.002	0.096	0.003	0	0.037	0.008
6	0.001	0.073	0.037	4.167	0.026	0.023
7	0.005	0.052	0.007	0	0.017	0
8	0.003	0.056	0.006	0	0	0.073
9	0	0.105	0.059	0.323	0.079	0.023
10	0.007	0.060	0.047	0.052	0.019	0.017
11	0.005	0.091	0.066	0.073	0.174	0.238
12	0.025	0.052	0.001	0.094	0	0
13	0.030	0.026	0	0	0.007	0
14	0.030	0.052	0	0	0	0
15	0.034	0.062	0.008	0.042	0.050	0.015
16	0.041	0.085	0.003	0.073	0.0077	0.013
17	0.034	0.075	0.040	0.073	0.016	0.012
18	0.029	0.097	0.039	0.115	0	0.009
19	0.032	0.073	0.039	0.104	0.006	0.015
20	0.041	0.073	0.036	0	0.097	0.031