The imprint of desalinated seawater on recycled wastewater: Consequences for irrigation in Lanzarote Island, Spain

摘要

Seawater desalination and recycling of urban wastewater originating from desalinated seawater are the only sources of irrigation water on the extremely arid (similar to 150 mm year(-1)) Spanish island of Lanzarote. Irrigation with these two types of water has been introduced over the past few decades-in traditional miffed agriculture systems as a means to increase crop production. The present study was carried ut to evaluate the long term impact (5-30 years) of irrigation with desalinated seawater (DSW) and recycled wastewater originating from desalinated water (RWW) on the island's soils used for fanning. The effects of irrigation were studied by evaluating the chemical characteristics of the topsoil of DSW-irrigated plots, RWW-irrigated plots and adjacent rainfed plots used as controls. The data indicate that irrigation with DSW and RWW has increased soil salinity by a factor of 1.9 and 3.4, respectively, and boron concentrations by a factor of 1.8 and 1.9, respectively, in relation to the control soils. Irrigation with RWW has also led to a rise in sodicity, where SAR values increased by a factor of 1.6 with respect to the control soil's. Apart from these effects DSW irrigation was not found to cause further adverse effects in regards to soil fertility. The long-term sustainability of these farming systems requires-substantial improvements-in DSW quality, Which in turn will improve the quality of the RWW. (C) 2012 Elsevier B.V. All rights reserved.