Aspects of environmental impacts of seawater desalination: Cyprus as a case study

Abstract

Cyprus relies on seawater desalination for a large part of its drinking water supply, with reverse osmosis providing more than 95% of the total desalination capacity in the country. Nevertheless, the environmental impacts of desalination for the Cypriot environment remain poorly understood. Using a combination of mining existing governmental and corporate survey data and reports, this study explores the scale of desalination in Cyprus, the impacts on the coastal marine environment and its overall carbon footprint. Surveys of Posidonia oceanica seagrass meadows show strongly reduced density of shoots and leaf surface area, respectively. Analysis of the available data relating to the overall production of desalinated water and energy consumption reveals that 68.7 million m 3 of desalinated water were produced in Cyprus in 2017, resulting in the release of 160 ktons of CO 2 equivalent, representing around 2% of the total carbon emissions in Cyprus. The results are directly applicable for understanding the impacts of brine discharge on seagrass meadows, one of the most common types of Mediterranean seabed ecosystems and useful for providing guidance to decision makers as they are striving to achieve a zero-carbon economy. strategies for achieving greater sustainability in terms of reduced CO 2 emissions and less brine discharge are discussed.

Annual cycle of mesozooplankton at the coastal waters of Cyprus (Eastern Levantine basin)

“…Cyprus, located in the Eastern Levantine basin is characterized by high seawater salinity and temperature ( Krom et al., 2014 ), some of the globally lowest nutrient ( Petrou et al., 2012 ) and Chl-a concentrations ( Bianchi et al., 1996 ) in surface layers and coastal waters, respectively. The ultra-oligotrophic characteristics of the Levantine basin are further reinforced in Cyprus by the extremely limited runoffs in its coastal waters, due to the frequent prolonged periods of drought ( Xevgenos et al., 2021 ) and the high number of dams (108 in total) constructed along the majority of streams of the island ( Water Development Department, 2022 ). In the coastal waters of Cyprus, filaments of cooler water are seen to extend offshore from Cape Akrotiri mainly during the summer period.…”

Impacts of Desalination Brine Discharge on Benthic Ecosystems

“…A total of 18 studies on desalination brine’s impacts on seagrass have been performed, yet all of them focused on seagrass species residing in temperate/subtropical waters ( Posidonia oceanica [ n = 12], Posidonia australis [ n = 2], Cymodocea nodosa [ n = 4]) (Table ). These studies have reported that seagrasses are negatively impacted by desalination brine. ,,,,− Specifically, it was found that the hypersaline brine caused a reduction in seagrass coverage , (∼40%), increased leaf necrosis, ,,, decreased leaf and shoot size (≤75% and 17–66%, respectively), reduced growth rates (26%), ,,,,, and reduced shoot abundance (12–45% reduction). ,, An increase in the amount of nitrogen found within the leaves and rhizome was linked to the reduction in glutamine synthetase activity due to brine exposer . Brine discharges were shown to decrease net photosynthetic rates by 12–33% ,, and to increase the dark respiration (up to 98%). ,,, P. oceanica leaves and rhizomes exposed to hypersalinities (116% above the ambient) for 1–3 months had increased carbohydrate concentrations; however, after three months of exposure followed by one month of recovery, the carbohydrate concentrations decreased by 35 and 28%, respectively .…”

“…21,44,47,67,108−112 Specifically, it was found that the hypersaline brine caused a reduction in seagrass coverage 21,112 (∼40%), increased leaf necrosis, 67,109,110,112 decreased leaf and shoot size (≤75% and 1 7 − 6 6 % , r e s p e c t i v e l y ) , r e d u c e d g r o w t h r a t e s (26%), 47,62,109,110,112,113 and reduced shoot abundance (12− 45% reduction). 62,110,112 An increase in the amount of nitrogen found within the leaves and rhizome was linked to the reduction in glutamine synthetase activity due to brine exposer. 67 Brine discharges were shown to decrease net photosynthetic rates by 12−33% 108,109,111 and to increase the dark respiration (up to 98%).…”

2024 roadmap on membrane desalination technology at the water-energy nexus

“…Thermal desalination technologies have also been employed for treatment of seawater desalination brines. Xevgenos et al demonstrated the use of forward-feed multiple effect distillation systems for concentrating the brine from 7% to 26% through the use of solar energy [72][73][74].…”