Trace metal Month Body tissue Sediment tissue/ sediment ratio (BF) V August 2.14 ± 1.98 0.52 ± 0.25 4.11   September 2.10 ± 1.72 0.58 ± 0.23 3.62   October 3.26 ± 2.87 0.68 ± 0.19 4.79 Mn August 40.14 ± 3.22 15.20 ± 2.32 2.64   September 28.31 ± 2.64 14.12 ± 0.54 2.00   October 33.32 ± 4.82 14.43 ± 1.21 2.36 Fe August 2112.29 ± 3.84 282.35 ± 5.41 7.48   September 2398.43 ± 4.75 247.60 ± 5.62 9.69   October 1668.21 ± 8.12 414.37 ± 0.98 4.03 Co August 2.12 ± 1.05 0.64 ± 0.05 3.31   September 3.98 ± 1.18 0.52 ± 0.12 7.65   October 1.75 ± 0.46 0.39 ± 0.10 4.49 Ni August 6.18 ± 3.89 1.42 ± 0.25 4.35   September 7.27 ± 4.92 1.44 ± 0.04 5.05   October 8.12 ± 6.53 3.18 ± 0.21 2.55 Cu August 89.23 ± 7.34 19.63 ± 2.82 4.55   September 33.86 ± 2.10 14.23 ± 2.18 2.38   October 36.31 ± 1.23 13.50 ± 3.25 2.69 Zn August 12.10 ± 2.12 3.02 ± 0.57 4.01   September 25.50 ± 3.12 10.61 ± 2.01 2.40   October 66.35 ± 1.29 12.82 ± 2.91 5.18 As August 0.96 ± 0.05 0.32 ± 0.06 3.00   September 0.84 ± 0.10 0.22 ± 0.09 3.82   October 0.78 ± 0.12 0.31 ± 0.08 2.52 Se August 10.78 ± 1.21 2.31 ± 0.98 4.67   September 11.35 ± 2.12 3.89 ± 0.82 2.92   October 9.86 ± 2.32 4.12 ± 0.58 2.39 Mo August 1.73 ± 0.87 0.22 ± 0.42 7.86   September 1.52 ± 0.21 0.97 ± 0.05 1.57   October 1.44 ± 1.02 0.86 ± 0.08 1.67 Ag August 2.33 ± 0.07 0.78 ± 0.10 2.99   September 2.01 ± 0.97 0.99 ± 0.21 2.03   October 1.98 ± 0.15 1.02 ± 0.92 1.94 Cd August 3.22 ± 0.21 0.89 ± 0.12 3.62   September 3.02 ± 1.01 0.95 ± 0.11 3.18   October 2.88 ± 1.00 1.21 ± 0.77 2.38 Pb August 14.12 ± 2.78 2.89 ± 1.21 4.89   September 10.12 ± 0.94 4.92 ± 4.10 2.06   October 12.44 ± 2.91 2.98 ± 2.00 4.17

Table 1: The mean trace metal content of Melanoides tuberculata and sediment samples upstream (control sites) of the effluent outfall in Alaro stream (parts per million, ppm)