Probabilistic human health risk assessment of trace elements in ballast water treated by reverse osmosis desalination plants

Abstract

Very few studies have paid attention to the transport of heavy and toxic metals via ballast water coming from different countries of the world. In the present study, ballast water samples (n = 83) were collected from ships, tankers and vessels of 21 different origins arriving at the two main ports of Qatar. Besides the basic physical parameters of pH, electrical conductivity (EC), and total organic carbon (TOC), concentrations of 24 elements (As, Sb, Al, Cd, Pb, Si, V, Ag, Zn, Cr, Mn, Ba, Co, Ni, Sr, Be, Cu, Tl, B, Fe, Se, Sn, Mo and U) were determined. In addition, the potential human health risks of drinking water treated by reverse osmosis (RO) were assessed using Monte Carlo simulations. Two scenarios were used to assess the risks to the general population, namely, seawater (baseline) and ballast water (worst-case scenario). Our results show significant differences among the tested elements, depending on the origin of the ballast water. The human health assessment showed that all hazardous quotients (HQs) were below the safety limits. However, for the ballast water scenario, thallium (Tl) HQs were 10 % above the safety level. Ballast water in Qatar does not pose risks for human health through drinking water, but ballast water discharges should take into consideration seawater catchments and potential toxic elements, especially Tl. Regular monitoring campaigns need to be performed.