As content below detection limit.

F value :"∗" statistically significant. Different letters in the same column denote significant statistical difference (P≤0.001) in mean metal contents in water samples from different zones

SD- Standard deviation.

WHO – World Health Organization.

USEPA – United States Environment Protection Agency.

**Table 3.** Heavy metal content of water samples (mg L-1)

All the metals in water samples were positively (P<0.01) correlated with each other (Table 4). In other words, metal concentration trends were identical and increased simultaneously for Pb, Cd, Zn, Cu, Co, Cr, and Ni.


\*\* Correlation is significant at the 0.01 level (two-tailed) (two-tailed; n=75)

**Table 4.** Correlation coefficients: water heavy metal concentrations

Higher concentrations of metals in zone 2 (Figure 2) may be attributed to the discharge of industrial effluents from various sources including untreated sewage, municipal waste and agrochemical runoff from the nearby villages directly into the river. The concentrations of Co and Ni were found to be negligible at all sites. Due to the neutral to alkaline nature of river water, most of the heavy metals have precipitated and settled as carbonates, oxides, and hydroxide bearing sediments and elevated levels indicates higher exposure risks to the benthic biota of the river. Based on the WHO [37] and USEPA [39] drinking water standards (Table 3) the results in the present investigation show that Pb, Cd and Cr at all sites and Ni at most sites far exceeded the prescribed limits. Cu values from zone 2 were above the USEPA [39] threshold. One Way ANOVA and Fisher's LSD test indicate the difference in mean content of each metal among zones was highly significant statistically (P ≤ 0.001).

**Figure 2.** Average heavy metal content in water samples

– 1.58 mg Cu l-1, 0.001 – 0.005 mg Co l-1, 0.80 – 9.37 mg Cr l-1 and 0.078 – 0.32 mg Ni l-1. As was

**Zone Pb Cd Zn Cu Co Cr Ni**

**Range** 0.025-0.041 0.05-0.136 0.7-1.02 0.86-0.98 0.002-0.004 2.87-4.23 0.078-0.12 **Avg.** 0.036a 0.088a 0.868a 0.916a 0.003a 3.55a 0.097a **SD** 0.007 0.037 0.128 0.046 0.0005 0.540 0.016

**Range** 0.066-0.095 0.159-0.341 1.37-1.76 1.27-1.58 0.004-0.005 6.42-9.37 0.17-0.32 **Avg.** 0.082b 0.243b 1.56b 1.40b 0.005b 7.914b 0.256b **SD** 0.013 0.072 0.166 0.112 0.001 1.138 0.071

**Range** 0.018-0.028 0.025-0.03 0.47-0.61 0.27-0.33 0.001-0.002 0.8-0.97 0.009-0.015 **Avg.** 0.023c 0.028c 0.54c 0.3c 0.001c 0.864c 0.01c **SD** 0.004 0.004 0.058 0.042 0.0003 0.066 0.003 **F value** \* \* \* \* \* \* \*

**WHO [37]** 0.01 0.003 5 2 - - - **USEPA [39]** 0.015 0.005 5 1.3 - - -

**World Average** 0.004 0.001 0.2 1.4 - - -

F value :"∗" statistically significant. Different letters in the same column denote significant statistical difference

All the metals in water samples were positively (P<0.01) correlated with each other (Table 4). In other words, metal concentration trends were identical and increased simultaneously for

**Pb** 0.970\*\* 0.985\*\* 0.875\*\* 0.924\*\* 0.960\*\* 0.962\*\* **Cd** 0.977\*\* 0.902\*\* 0.944\*\* 0.954\*\* 0.963\*\* **Zn** 0.925\*\* 0.953\*\* 0.976\*\* 0.966\*\* **Cu** 0.963\*\* 0.940\*\* 0.899\*\* **Co** 0.961\*\* 0.930\*\* **Cr** 0.947\*\*

**Cd Zn Cu Co Cr Ni**

not detected in any sample.

552 Environmental Risk Assessment of Soil Contamination

**1**

**2**

**3**

**Permissible limits**
