Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : CAN DATE PALMS PLANTED FOR URBAN LANDSCAPING PURPOSES SERVE IN THE PRODUCTION OF EDIBLE FRUITS ? AN EVALUATION OF TISSUE ELEMENT CONCENTRATIONS, FRUITS QUALITY AND HEALTH RISKS

Auteur : Al Nidawi, Khattab Omar Adam

Université de soutenance : United Arab Emirates University

Grade : Master of Science (MS) 2021

Résumé
More than 80.000 date palms are grown for ornamental purposes as part of public urban greenery in the city of Al Ain. The fruits that these palms produce, are often not valorized as food for humans, due to the fear that they might contain potentially hazardous pollutants, such as heavy metals. When palms are grown near roads or in urban environments, pollution might arise from the exhaust and dust produced by vehicles, industrial activities, as well as through urban waste material deposition, including irrigation with treated sewage effluent. On the other hand, many date palms grown for landscaping purposes might have a high potential to contribute to food production and security, should analyses reveal that their fruits are safe for consumption. The aim of the present study was thus to assess the overall quality of date fruits obtained from urban environments and roadside plantations in and around Al Ain. As part of this, possible heavy metal pollution of the fruits was investigated. In total, 34 date samples representing 11 date varieties were analyzed. All sampled palms were under long-term irrigation with treated sewage effluent. Element analysis of the potentially marketable dates revealed that their Fe, Zn, Cu, Mn, or Cr levels were too low to cause toxicity in humans, even at high daily consumption rates. In fact, concentrations of these trace metals, as well as other nutritional elements such as Ca, Mg, K and P in the sampled dates were in a rather low range compared with other plant-based food. This meant that the contribution of the date fruits to human supply with nutritional elements would be comparatively small at standard consumption rates. The concentrations of Pb, Co and Ni were in a safe range for human consumption, but Cd concentrations were slightly elevated across all analyzed samples. Ingestion of the sampled dates would exceed maximum permissible daily Cd intake at a rate of 50 – 70 g dry fruit pulp per day. This would correspond to 130 – 180 g fresh date fruits. Washing of the date fruits did not reduce their element concentrations. The latter were also in a similar range across all sampling locations and maturity groups. The findings of the present study suggest that the use of date fruits produced in urban environments and along roads would be possible, given that Cd concentrations are closely monitored, and sources of Cd pollution identified. The elaboration and implementation of valorization strategies for fruits harvested from urban dates would be facilitated by the ability of the site engineers, workers, and researchers to distinguish between the different date varieties. Experience with the date sampling pertaining to this study suggested that most workers and laboratory technicians are not able to do this. For this reason, a simple flowchart was developed as part of this thesis, based on which the most widely grown date cultivars in Abu Dhabi can be easily distinguished and classified. This decision matrix was accompanied by a reference photo repository, included into the literature review.

Présentation

Version intégrale