Evaluation of the Ecological Impact of Human Settlement on the Water Quality of Lower Cross River, Nigeria

Table 1

Summary of the physical and chemical parameters of the Lower Cross River study stations (January–August, 2011). Values are mean ± SE. The minimum and maximum values are noted in parentheses.

Parameters	Station 1	Station 2	Station 3	Statistical significance	Maximum permitted levels
					SON	WHO
Air temperature (°C)	29.89±0.55	31.99±0.63	30.84±1.36	𝑃>0.05
	(28.0–33.1)	(29.6–34.3)	(26.0–32.4)
Water temperature (°C)	29.68±0.91	29.89±0.94	30.11±1.04	𝑃>0.05	Ambient
	(26.1–32.0)	(26.0–32.3)	(26.0–33.2)
Transparency (m)	1.022±0.2438	1.202±0.3113	0.664±0.2501	𝑃>0.05
	(0.250–2.160)	(0.400–2.195)	(0.210–1.550)
Water level (m)	7.178±0.8205	5.236±0.8213	10.355±1.0901	𝑃<0.01
	(3.86–10.015)^A	(2.40–9.62)^A	(5.30–13.99)^B
TDS (mg/L)	28.0±2.04	27.88±3.29	26.0±2.37	𝑃>0.05	500	NHC
	(20.0–40.0)	(21.0–50.0)	(18.0–40.0)
TSS (mg/L)	0.0128 ± 0.005	0.0096±0.005	0.0089±0.004	𝑃>0.05
	(0.003–0.011)	(0.001–0.04)	(0.002–0.03)
TS (mg/L)	28.013±2.044	27.885±3.294	26.009±2.367	𝑃>0.05
	(20.0–40.01)	(21.0–50.001)	(18.0–40.0)
Flow velocity (m/s)	0.1136±0.0232	0.176±0.0287	0.1494±0.0339	𝑃>0.05
	(0.047–0.230)	(0.078–0.276)	(0.031–0.262)
Electrical conductivity (𝜇S/cm)	65.0±4.04	54.0±4.16	53.63±4.59	𝑃>0.05	1000
	(48.0–80.0)	(41.0–80.0)	(36.0–80.0)
pH	6.75±0.072	6.74±0.055	6.69±0.099	𝑃>0.05	6.5–8.5	NHC
	(6.30–6.90)	(6.50–7.04)	(6.10–7.06)
Alkalinity (mg/L CaCO3)	6.375±0.572	7.255±0.765	6.625±0.910	𝑃>0.05
	(3.0–8.5)	(3.0–10.0)	(3.0–9.5)
Dissolved oxygen (mg/L)	8.51±1.92	12.25±1.91	10.59±1.59	𝑃>0.05
	(4.6–18.2)	(4.0–19.8)	(5.0–13.6)
BOD5 (mg/L)	3.38±0.78	3.91±0.77	3.86±0.75	𝑃>0.05
	(2.10–7.60)	(1.70–8.20)	(1.75–7.10)
COD (mg/L)	161.63±14.54	116.21±12.27	87.98±10.75	𝑃<0.01
	(102.45–211.2)^A	(67.11–158.14)^B	(48.30–127.52)^B
Nitrate (mg/L)	5.37±0.90	4.36±0.83	3.04±0.52	𝑃>0.05	50	50
	(2.06–8.17)	(1.13–6.99)	(1.01–4.85)
Sulphate (mg/L)	3.51±0.62	2.69±0.569	1.60±0.418	𝑃>0.05	100	NHC
	(1.2–5.9)	(0.4–4.7)	(0.0–3.2)
Phosphate (mg/L)	0.348±0.099	0.20±0.061	0.124±0.042	𝑃>0.05
	(0.00–0.71)	(0.00–0.45)	(0.00–0.29)

Similar letters indicate means that are not significantly different from each other.
NHC means not of health concern at levels found in drinking water.
𝑃>0.05: not significant; 𝑃<0.01: significant.