Studies on heavy metals contents of Osun River at the pre-urban settlement and across Osogbo City, Nigeria

Figures & data

Figure 1. Water sampling locations (A–H) in Osun River, Osogbo. The triangle, square and star represent Ebunoluwa International School, National Open University and Fountain University, respectively

Table 1. The geographical coordinates of the sampling locations and average physico-chemical properties of Osun River.

	Geographical coordinates
SL	^oN	^oE	E (m)	DO (mg/L)	T (°C)	EC (µS/cm)	TDS (mg/L)	Salinity (ppt)	pH
A	7.74816	4.63181	325	2.97	28.3	725	452	0.08	7.5
B	7.74845	4.62896	320	2.90	27.9	918	549	0.07	7.2
C	7.75562	4.62262	332	3.77	28.1	396	383	0.08	7.0
D	7.75083	4.61933	328	3.37	28.1	396	307	0.08	7.0
E	7.73869	4.59610	319	3.03	27.4	783	612	0.06	7.2
F	7.74339	4.55583	317	2.80	28.4	599	340	0.07	6.6
G	7.76787	4.53930	298	3.00	28.5	761	335	0.17	6.6
H	7.77425	4.51036	290	4.00	28.3	665	558	0.1	6.5

Notes: SL, sampling location; E, elevation; DO, dissolved oxygen; T, temperature; EC, electrical conductivity; TDS, total dissolved solids. Except for the geographical coordinates and elevations, each value is an average of the three measurements obtained in July (2017), February (2018) and July (2018) study events.

Figure 2: Distribution trend of the concentrations of major heavy metals at different locations in Osun River. Each value is an average concentration of the three measurements obtained in July (2017), February (2018) and July (2018) study events.

Figure 3. Concentrations of the measured heavy metals in Osun River. Results are expressed as mean ± SE. Metal concentration is the average value of the concentrations obtained for each metal at the eight sampling locations during July (2017), February (2018) and July (2018) study events.

Table 2. Comparison of the average concentrations of heavy metals in Osun River with some guidelines for water.

	Heavy metal (mg/L)
Water	Pb	Cu	Mn	Ni	Zn	Cd	Fe	Cr	Co
Osun River (this study)	bl–0.08	0.02–0.36	bl–0.41	0.01–0.06	0.01–0.75	bl–0.03	0.01–4.47	bl–0.05	bl– 0.04
Likangala River	bl–0.71	bl	0–2.73	bl	0–0.14	0–0.05	0–10.3*	0–0.04	NA
Tembi River [8]	0.59–1.91	0.26–0.71	0.07–0.91	0.16–0.80	0.11–0.51	0.07–0.35	0.18–1.87	0.13–0.58	NA
World's major unpolluted rivers [9–11]	4 × 10^−5	1.4 × 10^−3	0.01	0.004	0.002	10^−6	0.05	10^−4	10^−4
Irrigation water standards [12]	5.00	0.20	0.2	0.20	2.00	0.01	5.00	0.10	0.05
Surface water standards [13]	0.005	1.30	0.10	0.14	NA	0.01	NA	0.16	NA
Drinking water standards [14]	0.00	NA	0.05	0.02	5.00	0.005	0.30	0.10	NA
Drinking water standards [15]	0.01	2.0	0.1^hb	0.07	3.00^nh	0.003	0.3^nh	0.05	NA

Notes: bl, below detection; NA, not available; hb, health-based guideline value = 0.4 mg/L; nh, no health-based guideline value is proposed in drinking water (but ≤0.3 mg/L of Fe is preferred); *, in form of Fe3+.

Shanbehzadeh S, Dastjerdi M, Hassanzadeh A, et al. Heavy metals in water and sediment: A case study of Tembi river. J Environ Public Health. 2014;3:1–5. doi: 10.1155/2014/858720

 Google Scholar

FAO. Water quality for agriculture. In: Ayers R, Westcot D, editors. FAO irrigation and drainage paper 29. Rome: Food and Agriculture Organization of the United Nations; 1994.

 Google Scholar

New Jersey water supply, surface water quality and pollutant loadings. A Technical Report for the Raritan Basin Watershed Management Project, 2002.

 Google Scholar

Brenner A, Hoekstra E. Drinking water quality standards and regulations. In: Ersoz M, Barrott L, editors. Best practice guide on metals removal from drinking water by treatment. London: IWA Publishing; 2012. p. 1.

 Google Scholar

WHO. Guidelines for drinking-water quality: incorporating 1st and 2nd addenda. Vol.1 recommendations, 3rd ed. Geneva: World Health Organization; 2008.

 Google Scholar