PHYTOAVAILABILITY, DYNAMICS AND PARTITIONING OF SOME HEAVY METALS IN VEGETABLE FARMSOILS IN ILORIN METROPOLIS.
No Thumbnail Available
Date
2018
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
UNIVERSITY OF ILORIN
Abstract
Vegetables are food materials that provide vitamins, minerals and fibres. These plants are raised during dry season (irrigated) and rainy season (rain fed). Anthropogenic activities involved in the raising of vegetables have been of great concern. There is little or no available information on the safety and qualities of irrigated vegetables. The objectives of this study were to: (i) determine the total heavy metal (HM) load in some farm soils and water; (ii) determine the phytoavailable heavy metals in soil; (iii) determine the heavy metal fractionation; (iv) determine available heavy metals in the vegetables; (v) investigate the heavy metal transfer and pathway in the vegetables; and (vi) evaluate the effects of the agronomic activity on the nutritional value of vegetable accessions.
The HM contents of the soil and water were determined using Atomic Absorption Spectrophotometer. Five vegetable accessions: Amaranthus hybridus (NG/AA/03/11/010, NG/AO/11/08/039 and NGBO125) and Corchorous olitorius (NG/OA/Jun/09/002, NG/OA/ 04/010) obtained from National Centre for Genetic Resources and BioTechnology, Ibadan were planted in different soils and irrigated with water collected from the different sites. The HM and the proximate analysis of vegetables were carried out. Data generated were subjected to Analysis of Variance and the means separated by Duncan Multiple Range Test set at 5% level of significance.
The findings of the study were that the:
i. range of heavy metal content of soils (mg/kg) and water (mg/l) respectively, were: 0.21 4.67 and 0.00-2.75 (Cd); 1.40–4.79 and 2.41-30.08 (Cu); 1.29-11.67 and 5.25-82.00 (Pb) in soils (mg/kg) and 0.00 0.07 and 0.00 0.07 (Cd); 0.00 0.34 and 0.52 1.68 (Cu); 0.04-0.63 and 0.21-0.54 ( Pb) for dry and rainy season respectively;
ii. phytoavailable HM range in soils (mg/kg) were: 0.11-0.67 and 0.00-0.13 (Cd), 0.17- 3.86 and 1.80-9.25 (Cu) and 0.50-5.83 and 0.276.25 (Pb) for dry and rainy, respectively;
iii. range of soils HM fractionation were: 0.00-1.67 and 0.00-1.17 (Cd); 0.21-6.67 and 0.00-11.67 (Cu) and 0.00-7.33 and 0.00-18.33 (Pb).
iv. available HM in the accessions were: 0.00-1.67 and 0.00-1.17 (Cd); 0.17-6.97; 0.00-23.00 (Cu); 0.00-6.67 and 0.00-18.33 (Pb) for dry and rainy season, respectively. However, most accessions accumulated Cd and Pb above the European Union (EU) and WHO/FAO standards for vegetables;
v. five vegetable accessions were good accumulators of Cd, Cu and Pb with bioaccumula tion coefficient of accessions greater than 0.5; and
vi. accessions had 6.18-10.14% (H2O); 1.21-5.56% (ash), 3.19-5.38% (crude fat and oil); 6.26-21.55% (crude protein); 1.07-2.58% (crude fibre) and 62.71-76.83% (crude protein) and 6.53-9.44% (H2O); 1.06-7.14% (ash); 2.84-5.83% (crude fat and oil); 7.02 23.50% (crude protein); 0.93 4.60% (crude fibre); 58.19 75.18% (carbohydrate) in dry and rainy season, respectively. However, the soils and water used made Cd, Cu and Pb more significantly (p<0.05) available to the vegetables.
The study concluded that soil and water used for raising vegetables are sources of HM pollution which can lead to health hazard. Farmers should therefore, be advised and encouraged to use treated wastewater for irrigation.
Description
Keywords
PHYTOAVAILABILITY, DYNAMICS, PARTITIONING, HEAVY METALS, VEGETABLE FARMSOILS, ILORIN METROPOLIS, VEGETABLES