ORIGINAL PAPER Assessment of water-rock interaction processes in the Karst Springs of Makook Anticline (Kurdistan Region, Iraq) using Sr-isotopes, rare earth, and trace elements Omed Mustafa 1,3 & Marion Tichomirowa 2 & Nicolai-Alexeji Kummer 1 & Broder Merkel 1 Received: 22 July 2015 /Accepted: 20 January 2016 # Saudi Society for Geosciences 2016 Abstract This work characterizes the karst springs of the Makook karst system (Kurdistan Region, Iraq) in terms of geo- chemistry of Sr-isotopes, rare earth, and trace elements. The aim of the work is to better understand water-rock interaction by geochemical means. Sources of elements, correlation of flow rate and the geochemistry of carbonate aquifers, and ef- fects of organic matter on the rare earth elements were investi- gated. Furthermore, the degree of karstification and the length of flow path were assessed. The 87 Sr/ 86 Sr ratio of two spring waters was similar to the ratio of rocks forming the aquifer, indicating that these rocks are their main and dominant Sr source. In the remaining six spring waters, the 87 Sr/ 86 Sr ratios were significantly higher than their corresponding aquifer rocks at the spring outlet and thus pointed to additional Sr sources. A temporal variation of 87 Sr/ 86 Sr in the Sarwchawa spring corre- sponds to flow rate changes. The chemical composition of the spring water reflects some important features of the chemical composition of their aquifers. Springs that stem from the Kometan aquifer (mainly limestone) are characterized by higher mineralization compared to springs that drained from dolomites of the Bekhme aquifer. Low to medium V 2+ , Rb + , P 3+ , and Si 4+ contents in waters correspond to springs fed by limestone and dolomite aquifers, whereas higher concentrations of these elements reflect water from a marly limestone aquifer (Shkarta spring). The release of these elements is related to the clay fraction of this aquifer. In contrast, the highest concentra- tions of Ni 2+ , Se 4+ , Mo 6+ , SO 4 2- , Sr 2+ ,F ¯ , and Ba 2+ were found in the spring fed by pure limestone but having the highest flow rate and the longest flow path. Therefore, these elements were enriched in the water due to longer interaction of the water with the rock. The temporal variation of REE concentrations in karst waters are controlled by flow, dissolved organic carbon (DOC), temperature, and redox reactions. Keywords Karst . 87 Sr/ 86 Sr isotope . Kurdistan Region . Trace elements . Sarwchawa . Carbonate rocks Introduction The Makook karst system is composed of Bekhme carbonate karst aquifers and represents one of the largest reserves of groundwater in the Kurdistan region, north-eastern Iraq (Stevanović and Iurkiewicz 2004). As in many parts of the arid and semi-arid areas, water scarcity is important in the region of interest (ROI). Therefore, investigating the available water resources in the Makook karst aquifers is a valuable endeavor. Flow regime, water-rock interaction, and hydrogeo- chemical processes were investigated for better understanding and management of water resources in the karst system. The hydrogeology and hydrogeochemistry of the karst system in Kurdistan in general and especially in the area of interest are not well investigated so far. In typical karst environments, weathering increases near the surface and water recharge distribution in both space and time can be determined (Liu et al. 2010). The geochemistry of water reflects interactions with their aquifers and can thus be used for a better understanding of flow pathways. * Omed Mustafa omedgeology@gmail.com 1 Institute of Geology, TU Bergakademie Freiberg, Gustav-Zeuner-Str. 12, 09599 Freiberg, Germany 2 Institute of Mineralogy, TU Bergakademie Freiberg, Brennhausgasse 14, 09599 Freiberg, Germany 3 Department of General Sciences, College of Basic Education, Charmo University, Kurdistan Region, Iraq Arab J Geosci (2016) 9:368 DOI 10.1007/s12517-016-2344-7