Agriculture & Horticulture

Biography

Biography: Asad Alkhader

Abstract

A survey was conducted to investigate the contamination of soils, plants and irrigation water with Cd, Pb and As heavy metals. Thirteen farms located from three locations characterized by intensive agricultural activities in Jordan (The Jordan Valley, Alyadoda, and Jarash) were selected for this purpose. Soil, plant and irrigation water samples were collected for chemical analysis: mainly heavy metals and P contents. The soil samples were collected from the 0-20 cm depth and the plant samples were collected from the available grown vegetables in the selected farms.
The tolerable level of Cd in fruit vegetables of 0.05 mg kg-1 fresh weight was approached by cucumber plant from farm no. 4 (0.06 ppm), tomato plant (0.06 -0.07 ppm), and exceeded by hot pepper (0.14 ppm). On the other hand, the permissible concentration of Pb in fruit vegetables of 0.1 mg kg-1 fresh weight was surpassed by tomato plants (0.24 -0.77 ppm); sweet pepper (0.14 ppm); cucumber plants (0.28-0.40 ppm) and hot pepper (0.88 ppm). Also, red cabbage 9 had Pb content (0.97 ppm) higher than the accepted level of 0.3 mg kg-1 of fresh weight for brassica vegetables. However, lettuce iceberg plants are within allowable levels of Cd and Pb of 0.2 and 0.3 mg kg-1 of fresh weight, respectively, for leafy vegetables. While, the Cd concentration in these lettuce plants ranged from 0.03 to 0.05 ppm (on fresh weight basis), the Pb concentration varied from 0.12 to 0.25 ppm (on fresh weight basis). All selected crops are safe with respect to As content as their contents of this heavy metal are much less than the established acceptable concentration of 1 mg kg-1 fresh weight.
The results suggest that the most probable sources of the heavy metals (Cd, Pb and As) in the collected samples from soils and crops from the selected farms are soil parent materials and pesticides application. However, P fertilizers additions for long time period might also contribute to the heavy metals contents of the plants and escalate the problem. Polluted air, also, represents a potential source for the heavy metals in the plants.
Chemical analysis of the irrigation water used in the selected farms suggest that such water can’t be considered as probable sources of heavy metals in the investigated soils from the selected farms. The levels of heavy metals in some selected fertilizers used by farmers in Jordan are, also, regarded below the permissible limits, but still likely sources of heavy metals in agricultural soils in under long-term application of such P fertilizers.