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Abstract
The objective of this research is to study the effect of pH, Ca, and Mg activities from nutrient solutions in the accumulation of nickel by barley plants. We obtained isotherm constants and statistically tested these by the Student t-test if the values obtained were significantly different among the different conditions studied. A Langmuir isotherm model was applied to the isotherm data and the constants, Kads and Γ max, were obtained for the each condition. There were six different pH experiments ranging from pH = 4 to 7, six different Ca experiments ranged from Ca = 2.93×10-4 mol/L to 1.00×10-1 mol/L, and five different Mg experiments ranged from Mg = 9.98×10 -4 mol/L to 3.00×10-2 mol/L. In the pH experiments, the six Kads obtained were statistically different to each other in shoots as were the six Kads obtained for roots. However, the six Γmax obtained for shoots were not statistically different from each other, and, neither were the six Γ max obtained for roots. In Ca, as well as in Mg experiments, each set of Kads and Γmax values obtained for shoots and, also for roots, were not statistically different in each part of the plant as a function of the concentration of Ca or Mg. Universal K ads and Γmax values were obtained and statistically validated for barley plants. For barley shoots the values were K ads = 0.34 mmol/L and Γmax = 11,900 mg/Kg, and for roots, Kads = 10.0 mmol/L and Γ max = 1390 mg/Kg. The universal Kads were valid for the Ca and Mg experiments and the Γmax values were valid for the pH, Ca and Mg experiments. These values indicate that H +, Ca2+ and Mg2+ in nutrient solutions do not affect the accumulation of Ni in barley plants under the conditions considered in this research study.
