Seasonal Variations in Trace Metals Contents of Some Vegetables Grown on Irrigated Farmlands along the Bank of River Benue within Makurdi Metropolis

Abstract

The seasonal variation in trace metals contents of Telfairia occidentalis (Fluted pumpkin), Amaranthus hybridus (Spinach) and Abelmoschus esculentus (Okra) were assessed in other to determine the impact of human activities at the river bank. The results of the study indicate mean level of zinc to range between (2.67-0.53) mgkg^-1 Talfairia occidentalis, (0.65-0.27)mgkg^-1 Amarantus hybridus and (0.24-0.44 mgkg^-1 for the first season, while in the second season, a range of (0.65-0.2) mgkg^-1, (4.21- 0.19) mgkg^-1 and 0.03-0.34 mgkg^-1 for T.occidentalis, A.  hybridus and A. esculentus was obtained respectively. The average levels of lead  for the two seasons was found to range between 0.08 - 0.26 mgkg^-1 and 0.01- 0.16 mgkg^-1 for T. occidentalis, 0.04-0.14 mgkg^-1 and 0.11- 0.27 mgkg^-1 for A. hybridus and

0.09 – 0.18 mgkg^-1 and 0.06 – 0.17 mgkg^-1 for A. esculentus. The level cadmium in T. occidentalis, A. hybridus and A. esculentus was found to range between 0.01 - 0.20 mgkg^-1 and 0.02 - 0.13 mgkg^-1,  0.04-0.11 mgkg^-1 and 0.06 - 0.14 mgkg^-1, and  0.7 - 0.17 mgkg^-1 and 0.04 - 0.15 mgkg^-1 for the first and second seasons  respectively. Copper levels were observed to be between 0.02- 0.10 mgkg^-1 and 0.01- 0.07 mgkg^-1 in T. occidentalis, A. hybridus, 0.02 - 0.07 mgkg^-1 and 0.02 - 0.17 mgkg^-1,  While   A. esculentus had 0.07 - 0.12 mgkg^-1 and 0.08 - 0.26 mgkg^-1 for first and second seasons respectively. Chromium levels in the three vegetables was found to be between results in T. occidentalis (0.06-0.14 mgkg^-1 ),  A. hybridus (0.02-0.44 mgkg^-1), A.  esculentus (0.2-0.40 mgkg^-1) during the first season, while in the second dry season, Chromium content of the vegetable varied as followed, T. occidentalis

(0.01-0.02mgKg^-1), A. hybridus (0.03-0.07mgkg^-1),  A. esculentus (0.01-04 mgkg^-1). There was significant difference (p<0.05) in chromium content of the plants. The result of the study revealed that the three vegetables were not harshly contaminated; hence the values obtained were far below the permissible levels accepted by the WHO/FAO. The implication is that farming activities at the river bank have not impacted sternly on the surrounding environment.

Keyword: Heavy Metals, Vegetables, Farms, irrigation, Makurdi,