Heavy metals concentration and distribution in soils and vegetation at Korle Lagoon area in Accra, Ghana

Figures & data

Figure 1. Map of the study area showing sampling sites.

Table 1. Summary of physicochemical characteristics of soils at different zones in Korle Lagoon area in Accra

Sites	S1	S2	S3	S4	S5	S6	Total means
pH	6.72	7.69	4.67	7.47	7.45	7.27	6.93
%0C	0.85	0.48	0.44	0.42	0.38	0.42	0.50
%OM	2.51	1.42	1.40	1.14	1.13	1.25	1.48
K^+	1.52	0.78	1.52	1.32	0.71	0.58	1.07
Na^+	6.15	2.13	6.07	3.69	3.12	2.01	3.86
Ca^2+	97.87	11.70	15.46	18.45	30.31	10.13	30.65
Mg^2+	73.40	8.80	11.60	14.00	23.00	7.60	23.07

Note: S1 = e-waste area, S2 = garden area, S3 = a reclaimed waste dump site, S4 = a recreational site, S5 = the estuary area of the Korle Lagoon and S6 = control.

Table 2. Summary of mean of heavy metal concentration of soils within 0–20cm depth in different sites in Korle Lagoon area in Accra

Heavy metals	S1	S2	S3 (mg/kg)	S4	S5	S6
Hg	0.67(0.021)a	ND	ND	0.04(0.006)b	0.003(0.003)b	0.03(0.002)b
Pb	183.66(0.02)a	1.28(0.02)bc	4.39(0.01)b	17.41(0.06)bd	12.65(0.06)b	3.33(0.06)b
Cu	202.99(1.27)a	3.47(0.05)bc	5.20(0.06)be	10.9(1.10)bd	6.39(0.06)bf	3.84(0.06)bg
Zn	37.33(0.58)a	0.83(0.05)bf	2.05(0.03)bc	6.33(0.01)bd	4.51(0.05)be	1.03(0.01)bg
Cr	56.0(1.15)a	3.03(0.10)b	2.28(0.58)b	2.36(0.06)b	20.99(0.06)b	2.63(0.17)b
Cd	103.66(1.73)a	3.55(0.58)b	ND	0.23(0.06)b	0.04(0.01)bc	4.35(0.06)bd
Ni	72(1.16)a	0.91(0.05)b	1.09(0.03)b	4.56(0.12)bc	1.59(0.01)b	1.48(0.003)b
Sn	704.87(2.71)a	27.39(0.86)b	8.77(0.112)bc	16.48(0.23)bd	14.85(0.20)be	24.71(0.12)bf
As	3.67(0.06)a	0.08(0.01)bc	0.47(0.06)bd	1.41(0.00)be	0.88(0.06)bf	0.04(0.012)b

Notes: Values in the parentheses are the standard error, S1 = e-waste area, S2 = garden area, S3 = a reclaimed waste dump site, S4 = a recreational site, S5 = the estuary area of the Korle Lagoon and S6 = control, SE = Standard Error, and nd = Not Detected. Means followed by a different letter(s) in the same row differ significantly (p = 0.05) according to Tukey’s Multiple Range Test.

Table 3. Comparison of heavy metal concentration in e-waste dumpsites of some cities of the world with data from e-waste site at the Korle Lagoon area in Accra

Cities	Hg	Pb	Cu	Zn	Cr	Cd	Ni	Sn	As	References
Wenling	0.47	187.30	180.66	343.19	101.29	3.00	48.97	–	–	Tang et al. (2009)
Ibadan	–	427.2	938.2	10,670	72.96	–	34.78	–	–	Timothy and Olajumoke (2014)
Lagos	–	209	–	262.2	27.05	28.032	64.17	–	–	Ofudje et al. (2014)
Guiyu, Guangdong Province	0.21	150	4,800	330	2,600	1.21	480	–	26.03	Li, Duan, et al. (2011)
Guiyu	–	222.8	684.1	572.8	–	1.36	278.4	3,472	–	Quan et al. (2015)
Bangalore, India	<0.05	126	429	192	54	0.478	–	–	–	Ha et al. (2009)
Accra	0.65	183.66	203.0	37.3	56	103.7	72.0	705.3	3.67	This research

Table 4. Geoaccumulation index (I_geo)

Heavy metals	S1	S2	S3	S4	S5	S6
Hg	−0.60	ND	−5.06	−4.67	ND	ND
Pb	3.30	−3.87	−2.49	−0.11	−0.57	−2.10
Cu	1.30	−4.57	−4.43	−2.93	−3.69	−3.99
Zn	−1.49	−7.00	−6.67	−4.05	−4.54	−5.68
Cr	−1.42	−5.63	−5.84	−5.99	−5.65	−6.14
Cd	8.43	3.56	3.86	−0.51	−2.94	ND
Ni	−0.64	−6.95	−6.25	−4.63	−6.14	−6.70
Sn	7.88	3.19	3.04	2.46	2.31	1.55
As	0.44	−5.08	−6.22	−0.94	−1.62	−2.55

Notes:

S1 = e-waste area, S2 = garden area, S3 = a reclaimed waste dump site, S4 = a recreational site, S5 = the estuary area of the Korle Lagoon and S6 = control.

Table 5. Enrichment factor (EF) of heavy metals for soil at different zones in Korle Lagoon area in Accra

Sites	S1	S2	S3	S4	S5	S6	PLI
Hg	848.72	ND	38.58	51.44	ND	ND	1.534
Pb	9.71	0.07	0.18	0.92	0.67	0.23	2.970
Cu	0.55	0.01	0.01	0.03	0.02	0.01	0.705
Zn	0.06	0.00	0.00	0.01	0.01	0.00	0.124
Cr	0.05	0.00	0.00	0.00	0.00	0.00	0.115
Cd	21,328.05	730.41	895.01	47.32	8.23	ND	93.18
Ni	0.11	0.00	0.00	0.01	0.00	0.00	0.181
Sn	1,450.26	56.35	50.84	33.91	30.55	18.04	66.43
As	9.32	0.20	0.10	3.58	2.24	1.19	0.606

Notes: S1 = e-waste area, S2 = garden area, S3 = a reclaimed waste dump site, S4 = a recreational site, S5 = the estuary area of the Korle Lagoon and S6 = control, PLI = pollution load index, nd = Not Detected.

Table 6. Summary of heavy metal concentration in vegetation at the Korle Lagoon area in Accra

Heavy metals	S1	S2	S3 (mg/kg)	S4	S5	S6
Hg	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001
Pb	36.72(0.57)a	0.69(0.34)bc	0.48(0.05)bd	<0.001	3.81(0.12)be	0.55(0.80)b
Cu	95.56(0.58)a	10.13(1.04)bc	0.21(0.03)bd	6.92(0.05)be	5.48(0.27)bf	0.21(0.03)b
Zn	34.92(0.59)a	8.04(0.20)bc	14.84(1.13)be	7.88(0.06)bf	7.36(0.40)bg	1.33(0.12)b
Cr	1.56(0.12)a	1.21(0.11)ac	1.08(0.05)a	3.84(0.04)b	3.52(0.29)b	1.23(0.57)a
Cd	1.64(0.12)a	0.83(0.09)bc	0.92(0.04)be	0.44(0.03)b	0.32(0.06)b	0.25(0.06)b
Ni	2.0(0.12)a	5.28(1.72)a	2.25(0.03)ad	2.2(0.12)ae	6.80(0.58)b	0.59(0.11)ac
Sn	22(1.15)a	17.17(1.47)a	3.23(0.06)b	2.52(0.12)b	4.64(0.38)b	22.29(4.89)a
As	0.32(0.05)a	nd	0.12(0.01)b	0.08(0.01)bc	0.16(0.12)be	0.19(0.01)b

Notes: S1 = e-waste area, S2 = garden area, S3 = a reclaimed waste dump site, S4 = a recreational site, S5 = the estuary area of the Korle Lagoon and S6 = control, SE = Standard error, nd = Not Detected. Means followed by a different letter(s) in the same row differ significantly (p = 0.05) according to Tukey’s Multiple Range Test, values in the parentheses are the standard error.

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