Elemental analysis of the edible fruit of Carpobrotus dimidiatus (from Kwazulu-Natal, South Africa) and the influence of soil quality on its elemental uptake

Abstract

Carpobrotus dimidiatus is an indigenous South African medicinal plant species from the Aizoaceae family that bears edible fruit that is consumed for nutritional value. In this study, the elemental distribution in C. dimidiatus fruit and growth soil from fifteen sites in KwaZulu-Natal (South Africa) was determined along with soil pH, soil organic matter and cation exchange capacity, to assess for nutritional value and the effect of soil quality on elemental uptake. The results showed elemental concentrations in fruit to be in decreasing order of Ca (6235–32755 mg kg−1) > Mg (2250–5262 mg kg−1) > Fe > Mn > Zn (20.9–50.6 mg kg−1) > Cu (3.83–20.6 mg kg−1) > Pb > Cr > Cd > As ∼ Co ∼ Ni ∼ Se and no potential health risk due to metal toxicity from average consumption. For sites that had high levels of Cd and Pb, bioaccumulation occurred from atmospheric deposition. Concentrations of elements in soil were found to be in decreasing order of Fe (1059–63747 mg kg−1) > Ca (1048–41475 mg kg−1) > Mg > Mn (9.76–174 mg kg−1) > Cr (1.55–135 mg kg−1) > Zn (0.76–58.2 mg kg−1) > Se > Cu > Ni > Pb > Co > As ∼ Cd with no evidence of heavy metal contamination. This study revealed that the plant inherently controlled uptake of essential elements according to physiological needs and that the concentrations of essential elements in the fruit could contribute positively to the diet.