Abstract The Dead Sea is worldwide a major bromine provider for industry with an average concentration of 5.2 g/l of bromide compared to 0.065 mg/l in seawater and with a Cl/Br weight ratio in the Dead Sea water of about 42 compared to around 300 in oceanic water. The origin of the high bromide concentration in the Dead Sea has not yet been adequately clarified. In the course of this study, the bromide concentrations in the different surface and groundwater bodies in Jordan were analyzed and the types of rocks with which these waters were in contact were identified. Analyses carried out up to about 30 years ago and recent analyses confirm the natural origin of bromide in the water and also confirm that the analyzed sources are not polluted by anthropogenic bromide sources. It was found that a variety of these surface and groundwater sources contain high concentrations of bromide which discharges into the Dead Sea and contribute to its high bromide concentration. The present study concludes that the late Cretaceous early Tertiary oil shale deposits form the major source of the bromine species in the surface and groundwater feeding the Dead Sea. Some bromide is also contributed by the Triassic and Jurassic rocks containing evaporated salts containing bromides. Phosphate rocks of late Upper Cretaceous age contribute also with appreciable amounts of bromine species to the different water sources and hence to the Dead Sea water. At present, dissolution and erosion of bromide-rich sediments laid down by the predecessor water bodies of the present Dead Sea such as the Lisan Lake are being transported into the Dead Sea and contribute relatively large amounts of secondary bromide to the Dead Sea water
Keywords Bromide.DeadSea.Triassic rocks.Oil shale.Phosphate.LisanFormation
Introduction
Bromide is generally found in seawater and in brines generated by seawater evaporation as well as in evaporates such as Br-carnallite MgBr2KBr.6H2O. It is also found enriched in marine organisms (Krejci-Graf 1963) and as exhalations of magmatic or volcanic gases. The bromide concentration in seawater is around 0065 mg/l, and the Cl/Br mass ratio (henceforth Cl/Br ratio) is around 300. The Dead Sea water has a Br− concentration of 5200 mg/l and a Cl/Br ratio of 42 (Neev and Emery 1967;Bender1968; Zak 1997). Evaporation processes affecting surface and groundwater resources feeding the Dead Sea cannot alone explain the high bromide concentration and the low Cl/Br ratio in the Dead Sea water except when only chlorides and not bromides have precipitated from the Dead Sea water. Because the Cl/Br weight ratios in the Dead Sea water is 42 compared to oceanic water of 300, then from the Dead Sea and its ancestor seas at least 7.1 (300/42) times chloride salts must have precipitated compared to the present concentrations of Cl in the Dead Sea water, if the Dead Sea and its ancestor seas would have received their water from similar sources as the ocean. In Jordan, manysurfaceandgroundwaterresources contain
Br− concentrations which are significantly higher than the majority of resources worldwide. The reason for this phenomenon has not yet been well understood (Bender 1968;Abu Ajamieh 1980;Abu-Zir1989).
This study focuses on the elevated concentration of Br− in the Dead Sea water and the low Cl/Br ratio together with the high Br− concentrations in many surface and groundwater resources feeding the Dead Sea. It also has the aim of clarifying the sources of Br− in both surface and groundwater bodies and consequently in the Dead Sea water. For that purpose, the electrical conductivity values (EC), F−,I−,and Cl− concentrations were also measured to establish the relationships with the source rocks. In addition, rock samples of phosphate, oil shale, Triassic and Jurassic deposits, and Lisan Lake deposits were analyzed for their Br− contents in order to correlate these contents with those in the waters feeding the Dead Sea.
The time period of sampling and analyses extended over the last three decades, and each source was sampled several times in the past and recently to make sure that the bromide content in the water is natural and isnot a result of pollution by man’s activities.
Geological background
Sedimentary rocks cover almost the entire area of Jordan. Only in the southwest, Precambrian plutonic and metamorphic rocks belonging to the Arabian Shield are exposed (Fig. 1). The Arabian massif extending northeastwards be yond Jordan was peneplained in the Late Precambrian and was then gradually covered by younger sediments of terrestrial and marine origins (Bender 1968; Bandel and Salameh 2013). The thickness of these sediments increases in a north-easterly direction where progressively younger sediments are exposed. The sedimentary sequence overlying the Precambrian
rocks starts with clastic sediments mostly of continental origin. During the Middle Cambrian time, the ancient Tethys transgression to the southern part of Jordan and marine calcareous sands were deposited. This transgression was followed by a regression in the Late Cambrian time with the deposition
of continental sands (Bender 1968). During the Early Ordovician, the Tethys again transgressed to the south beyond the Cambrian transgression line, and mainly marine calcareous and sandy sediments were deposited. These facies lasted until the Early Devonian. During the Late Silurian, clastic rocks were deposited. Rocks of the Middle and Upper Devonian, Carboniferous, or Permian ages are not encountered in southern Jordan but they are found in wells in northern Jordan (Bender 1968). In the northern parts, starting from Wadi Mujib and Zerqa Ma’in, Tethys transgressed from the north and east of the Dead Sea; Permo-Triassic, Triassic and Jurassic sandstones, siltstones, and clay stones start to be deposited and extend northeastwards beyond the country borders (Fig. 2) (Bandel and Salameh 2013). During the Early Cretaceous, clastic sediments consisting mainly of semi-indurated sands with very thin clay lenses
were deposited. The mostly sandy sequence of Cambrian to Upper Cretaceous age forms the lower aquifer complex in Jordan. In the Late Cretaceous period, a new transgression followed, reaching far beyond earlier transgression to the south and shallow, marine, calcareous, and marly sediments were deposited. This sedimentation cycle continued during the Tertiary with greater thicknesses being deposited in the gentle, low-slope basins that formed during rifting. This sequence forms the upper aquifer complex (Bender 1968). In northeast Jordan, basaltic rocks of Quaternary age overlying older rock units cover about one-seventh of the entire territory of Jordan (further details are given in Burdon 1959;
Bender 1968). The prominent geologic structure, which has affected the palaeo- as well as the present hydrogeology of the area, is the Jordan Graben and its development to its present state. During the Late Miocene, the Jordanian plateau was uplifted along a N-S line, which was parallel to the later Jordan Graben axis. Elevated ridges on both sides of the gra ben were formed, and the graben proper started to be downfaulted (Burdon 1959; Bender 1968; Bandel and Salameh 2013). In the Jordan Graben, different ancestral lakes of the Dead Sea have formed since its formation with varying water levels and sediment types including deposits with high concentrations of evaporates (Bender 1968; BandelandSalameh 2013).
Aquifer systems
The main geological units based on hydrogeological classification from Precambrian to recent rock formations are illustrated in Fig. 2.
Deep sandstone aquifer complex
This complex forms one unit in southern Jordan. To the north, gradually thick siltstone and limestone and marl sequences separate it into two aquifer systems, which nonetheless, remain hydraulically interconnected.
A . Disi Group aquifer of Paleozoic age
This is the oldest, and in the north, the deepest water-bearing sediment sequence inJordan, consisting of sandstones
and quartzite. It crops out only in the southern part of Jordan and along Wadi Araba–DeadSeaRift Valley and underlies the entire area of Jordan (NWMP 1977).The southern part of the complex forms the freshwater aquifer of the upper Wadi Yutum–Disi–Mudawwara area.
B. Kurnub and Zerqa Groups aquifer of Jurassic-Lower Cretaceous age
This is also a sandstone aquifer underlying the area of Jordan and overlying the Disi group aquifer. It crops out along the lower Zerka River basin and along the escarpment of the Dead Sea, Wadi Araba, and Ras Naqb areas. Wells drilled in this fine-grained sandstone aquifer have fairly good yields. Direct recharge, however, is limited to small outcrop areas (NWMP 1977). The groundwater in this aquifer, aside from the recharge areas, is significantly mineralized (Salameh 1996). TheKurnub–Zerqaaquifer system is being exploited mainly in the lower Zerka River catchment and in the Baqa’aareas. The direction of groundwater flow in this aquifer system is generally towards the west; towards the northeast in the
Fig. 2 Stratigraphy of rock formations in Jordan, their thicknesses, and hydraulic classification
southern part of Jordan, towards the west in central Jordan, and towards the southwest in northern Jordan (Salameh and Udluft 1985). The sandstone aquifer complex consisting of Disi, Zerka, and Kurnub groups is interconnected through the Khreim group and hence it is regarded as one basal aquifer and hydraulic complex underlying the whole territory of Jordan.
Upper Cretaceous hydraulic complex
This complex consists of an alternating sequence of limestone, dolomite, marlstone, and chert beds. The total thickness in central Jordan is about 700 m. The limestone and dolomite units form aquifers excellent in water quality and yield. The lower portions of this sequence (A1/2), consisting of about 200 m of marls and limestone, possess in some areas relatively high permeability and form a potential aquifer. An
aquitard (A3) consisting of about 80 m of marl and shale overlies the A1/2 and separates it from the overlying A4 aquifer. The latter consists of pure semi-crystalline, karstic limestone, and hence it has very high permeability and porosity. The A4 aquifer crops out along the highlands and is recharged there. To the east, this aquifer is confined by the overlying aquitard consisting of marl and limestone (A5/6). The A5/6 aquitard is overlain by the most important aquifer of the sequence, namely the Massive Silicified Sandy Units, A7/B2, which consists of limestone, chert-limestone, sandy limestone, phosphates, and marly limestone. It crops out along the highland and is being recharged there. To the east, like the A4aquifer, it becomes a confined aquifer, overlain by layers of marls. In the eastern desert, the whole aquifer complex (A1–A7 and B1 and B2) is overlain by a thick marly and bituminous sequence (B3), forming a competent confining bed. Therefore, in some locations, flowing artesian wells are drilled into the underlying aquifers.
The groundwater flow in this complex is directed from the recharge mounds of the highlands locally to the western escarpment of the Rift Valley within the faulted blocks and mainly to the east, where it discharges along deeply incised wadis, or flows further eastwards. Along its way to the east, a part of the water seeps to the underlying sandstone aquifer complex, and the other part appears in Azraq and Sirhan basins as spring discharges.
Shallow aquifers hydraulic complex
It consists of two main systems:
A. Basalt aquifer
Basalts extend from the Syrian Jabel Arab-Druz area south ward to the Azraq and Wadi Dhuleil region, forming a good aquifer of significant hydrogeological importance, with a maximum thickness of around 400 m (BGR 1996). The recharge to this aquifer is provided by precipitation in the elevated area of Jabel Arab-Druz, 1300 masl. From there, the groundwater moves radially in all directions. Geological structures favored the formation of three main discharge areas namely, the upper Yarmouk River, the Wadi Zerka, and the Azraq basins.
B. Sedimentary rocks and alluvial deposits of Tertiary and Quaternary ages
These rocks form local aquifers overlying partly the previously mentioned aquifer complexes or they are separated from them by aquitards. They are distributed all over the country, but are mainly concentrated in the eastern desert, in the Wadi Araba–Jordan Valley, in the Jafr basin, and in the Yarmouk River area.Recharge takes place directly over these aquifers as in the case of the Azraq basin or via upward movements from the underlying aquifers, or from the surrounding older aquifers, by lateral flows, such as the cases of the recent deposits of the Jordan and Wadi Araba valleys. The groundwater flow in the Late and Post Tertiary sediments, in the eastern desert, is directed radially towards the Azraq oasis and towards the Jafr depression coming from the west and south of the Jafr basin. Groundwater flow in the sediments of the Wadi Araba-Jordan Valley depends on the underground conditions, but it mainly flows laterally, from the eastern escarpments into the valley deposits, then flows west towards the center of Wadi Araba-Jordan Valley and from there to the Dead Sea.
C. Lisan Formation
The Lisan Marl Formation covers the banks of the Lower Jordan River along its course from Lake Tiberias to the Dead Sea. The Lisan Formation is restricted in its presence to the central part of the Jordan Valley on both sides of the Jordan River. It consists of laminated sediments of alternating clayey silt, calcareous
silt, aragonite, and gypsum. Gypsum and halite crystals can be observed within the sediment (Bender 1968; Bandel and Salameh 2013). The Lisan Marls were deposited in the Lisan Lake, the ancestral water body of the Dead Sea which started shrinking with the beginning of the Holocene to form the present day Dead Sea.
HALIDE concentrations and water salinity in the various water sources in Jordan
Analyses are partly obtained from Abu Ajamieh (1980), Salameh and Rimawi (1988), Abu-Zir (1989), El-Nasser (1991), Rimawi et al. (1992), Salameh (1996), Sawarieh (2005); Moeller et al. (2006a, b), dry fall analyses from Koenig (1994), and rock analyses were carried out in the Engler-Bunte Institute, KIT Prof. F. Frimmel. The time frame of sampling extends over at least 35 years, but all sources were sampled during the last few years to check older results and to assure their validity. The sampled sources of flood and baseflows, groundwater, and precipitation water generally in remote areas, far away from development centers with industrialization and urbanization and therefore the chemistry of the sampled sites did not show any major changes in the concentrations of the different analyzed parameters or trends in these
concentrations. Analyses done in the course of this study were performed by measuring EC, pH, and T values in the field using WTW meters. Cl− was analyzed in the laboratory by titration with AgNO3− and Br− by using WTW-made specific Br− electrodes (Deutsche Einheitsverfahren zur Wasseruntersuchung,
1960 and recent updates)^ and the BStandard Methods for the Examination of Water and Waste Water (AWWA 2009,recent updates)^. The electrical conductivity value (EC), which can be used as surrogate for the total dissolved solids content or salinity of water, is used throughout this article, because it is the parameter which is easily and directly measured in the field and reflects in a very good way the total dissolved solids content (EC values are given in microSiemens per centimeter, all others in milligrams
per liter and Cl/Br ratios in milligrams per liter. East (E) and North (N) Coordinates in the tables are given
in Palestine Grid).
Precipitation waters
The composition of precipitation water was analyzed in 12 stations (Figs. 3 and 4) distributed all over Jordan for the duration of 3 years. Precipitation water falling in 1month’s periods was collected from each station and analyzed for the major constituents and the different halogens. In the Jordan University station, each precip itation event was sampled and analyzed. Some events were even sampled every 0.5 to 1 h to study the out-raining effects on the concentrations of the different parameters (Salameh and Rimawi 1988). Table 1 gives a summary of the average weighted salinity and halides concentrations for the 12 precipitation water collection stations. Generally, samples were collected at the start of a precipitation event containing higher salt concentrations but which decreased with continuing precipitation. The EC values ranged from a few hundred microSiemens per centimeter at the start of an event first flush and decreased down to a few tens of microSiemens per centimeter after out-raining. The weighted average (concentration in a sample × its volume/sum of volumes of all samples) EC values ranged for the different stations from 75.6 μS/cm for the University of Jordan station to 272.7 μS/cm for Azraq station in the eastern desert of Jordan. These EC values are functions of areas elevation above sea level, type of prevailing climate (arid, semi arid, or Mediterranean), exposure to dust storms and origin of cold fronts producing precipitation, Mediterranean, Siberian, Indian, or Red Sea depressions (Salameh and
Rimawi 1988). The concentrations of the individual parameters including Br−,Cl−,F−, and I− show the same behavior as those of the EC values; higher concentrations at the start of a precipitation event decreasing with the continuation of precipitation. The Br− concentrations in all the precipitation events in the 12 stations ranged from detection limit (a few micrograms per liter) to 2.5 mg/l, and the weighted average ranged from 0.021 in Irbid station to 0.575 mg/l in Rabba station in the highlands east of the Dead Sea. The high concentrations of Br− in Rabba and Shoubak stations can be attributed to aerosols of the Dead Sea, in Deir Alla to dust produced by the erosion of Lisan Formation, and in Khalidiya to the imtensibe use of Biocides containing bromide. The F− concentrations and the weighted average ranged in all samples from 0.001 to 0.394 mg/l and from 0.039 to o.099 mg/l, respectively. The I− concentrations and their weighted average ranged from 0.001 to 0.044 mg/l and from 0.0046 to 0.074 mg/l, respectively.
The desert areas as affected by phosphate mining and the Jordan Valley area (University of Jordan Farm in Deir Alla) showed the highest weighted averages of F− and I− concentrations. The Cl− weighted average concentrations for all stations ranged from 8 to 72.1 mg/l in coincidence with the EC values, which reflects the effect of dust in precipitation water. The Cl/Br mass ratios are generally less than 200 and only Queen Alia airport, Irbid, and Salt stations showed higher ratios. The analyses show that the Br− concentration in the precipitation water is relatively high. It seems to be affected by aerosols of the Dead Sea, the Lisan Deposits, phosphate and potash mining and processing, and the application of Br−containing biocides in agriculture, especially in the Jordan Valley area. It seems also that Cl and Br follow different mechanisms during transform from one state to another.
Dry deposition
Dry deposition (dust) contributes to the chemistry of the different surface and groundwater. Dry deposition in different areas in Jordan was collected over 1 year and analyzed on its contents of halides (Koenig 1994). The Cl− dry deposition ranged from around 69 mg/m2/year in the Jafr basin, in the southeastern desert, to about 8100 mg/m2/year in the Deir Alla area, in the central Jordan Valley area (Table 2). The Br− dry deposition
ranged from around 2.7 mg/m2/year in the Jafr basin to about 42.3 mg/m2/year in the Deir Alla area. Table 2 shows that the Br− dry deposition input in the desert areas are less than those of the highlands and of the Jordan Valley area. The F− and I− inputs range from 0.612 to 12.89 mg/m2/year and from 0.105 to 1.69 mg/m2/year, respectively. The Cl/Br ratios in the dry deposition range from 25 in the Jafr basin to 296 in the Irbid area. It seems that the phosphate and potash deposits and their mining along the plateau and the southern shores of the Dead Sea enhanced by the prevailing winds are the factors controlling the dry deposition contents of halides.
Fig. 4 Detailed map of sampling sites and major locations in the northern part of Jordan
Floodwater
Floodwaters of different wadis discharging into the eastern desert and into the JordanValleywere analyzed on their salinity, EC values, Cl−, Br−, F−, and I− contents (Table 3). In general, the Br− concentration in floodwater does not exceed a few tens of micrograms per liter. Only in Wadi Wala which drains the areas covered by oil shale the concentrations reach a few hundred micrograms per liter. Also, the water of the Jordan River at the Baptism Site of Jesus which consists of flood and base flows contain 13 to 29 mg/l of Br−,respectively. This water is strongly affected by the Lisan Marls, which contain high bromide concentrations (see below bromide in the Lisan Formation). The high diversity of flood flow Br concentrations is attributed to the types of rocks covering the catchment area. Areas covered by Bituminous Marl, evaporate-containing Triassic and Jurassic rocks, phosphates, and Lisan Marl contribute higher Br concentration and lower Cl/Br ratios to the flood waters. The F− and I− concentrations in wadis without base flows such as Muwaqqar, Khalidiya, Dabaa, Thiban, Mafraq
Table1 Electrical conductivity (μS/cm), halide concentrations (mg/l),and the chlorine to bromine (Cl/Br) massratiosin precipitationwaterinJordan (resultsof3yearssamplingand analyses with minimum of 10
samples but generally more than 17samples from each site.For site locations see Fig.1)
| Rainfall station | Br− | F− | I− | EC | Cl− | Cl/Br | E | N |
| University of Jordan, Amman | 0.049 | 0.047 | 0.01 | 75.6 | 9.03 | 183 | 232.42 | 158.47 |
| Ruseifa | 0.113 | 0.060 | 0.008 | 136.4 | 9.62 | 84.9 | 249.79 | 159.19 |
| Khalidiya | 0.226 | 0.038 | 0.010 | 165.1 | 11.69 | 51.7 | 272.50 | 176.20 |
| Azraq | 0.17 | 0.097 | 0.074 | 272.7 | 23.38 | 137.5 | 326.07 | 145.68 |
| Rabba | 0.575 | 0.050 | 0.022 | 114.3 | 13.93 | 24.3 | 220.10 | 75.51 |
| Shoubak | 0.341 | 0.079 | 0.007 | 96.5 | 9.77 | 28.6 | 208.98 | −7.69 |
| Salt | 0.066 | 0.039 | 0.006 | 98.7 | 14.77 | 223 | 218.69 | 160.51 |
| Irbid Town | 0.021 | 0.042 | 0.019 | 95.2 | 8.02 | 381 | 230.20 | 218.85 |
| Irbid weather station | 0.016 | 0.018 | 0.038 | 192 | 18.90 | 120 | 229.44 | 218.65 |
| Uni. Farm Deir Alla, J. Valley | 0.315 | 0.099 | 0.014 | 159.8 | 16.56 | 52.6 | 206.46 | 170.29 |
| Queen Alia Int’l Airport | 0.093 | 0.055 | 0.029 | 206 | 72.10 | 775 | 246.27 | 126.60 |
| Muwaqqar | 0.129 | 0.081 | 0.013 | 165 | 17.68 | 137 | 255.09 | 136.65 |
Safawi–Rweished, andAzraq range between0.012and 0.44mg/land between< 0.0001 and 0.1 mg/l, respectively. The EC values of flood water of wadis draining only flood flows are less than 250μS/ cmin general.But at the beginning of flood event, the EC values may reach 500μS/cmasa
result of overland flow and dissolution of salt crusts for mingat the top oils during the dry season.
In the Jordan River water, the EC values range from 6010 to 9800μS/cm , reflecting the mixing of flood and base flow waters.The Cl/Br ratio sin desert wad is draining only flood water are very high and exceed 400 and in wad is draining to the Jordan Rift Valley the ratios decrease to less than 200 and are generally below 100. In the water of the Jordan River at the Baptism site,the ratio ranges from 75to144.
Baseflow
Wadis originating in the highlands and flowing to the west towards the Dead Sea and the Jordan River discharge base flows which generally emerge from the following aquifers:
- Basalt aquifer
- Tertiary: Rijam and Shallala (B4 and B5), chalk marl aquifer
- Upper Cretaceous: Amman Wadi Sir (B2/A7), silicified and phosphatic limestone aquifer
- Lower Cretaceous: Kurnub (K), sandstone aquifer
- Triassic and Jurasic: Zerqa (Z), siltstone semi-aquifer
The Br− contents of the base flow waters which are generally mixtures of different aquifer waters range from 0.30 in Wadi Waqqas which water originates from the B2/A7 aquifer to 0.66, 0.65, and 0.80 μg/l in the Wadis Kafrain, Kureima, and Wala, respectively, which water originates from the B2/ A7 and A1–6 aquifers (Table 4). Waters in wadis draining the B2/A7, the A1–6, and Kurnub aquifers contain Br− concentrations between 1.0 and 2.0 μg/l. Some of the base flow waters in such wadis (Hasa, Mujib, Mashare’a, Arab, and Yarmouk) are affected by the oil shale covering parts of their catchment areas. The EC values of the base flow water range from 450 μS/cm in Wadi Shueib to 1700 μS/cm in Wadi Mujib.The F− and I− concentrations range from 0.25 to 0.98 and from 0.014 to 0.045 mg/l, respectively, with the exception of the F− concentration of Wadi Kafrain of 0.23 mg/l which results from the contributions of the Zerqa group aquifer to the base flow of that wadi. The F− and I− concentrations reflect water-rock interactions with limestone and leached sandstone aquifers in Jordan. The Cl/Br ratios range from 47 in Wadi Shueib, which seems to be affected by the pharmacy industry in the catch- ment area, to 340 in Wadi Mujib, but most of the base flows show ratios of less than 300 and higher than 75.
| Table 2 Halides inputs in the dry deposition (mg/m2/year) in different areas in Jordan (1-year | Sampling site | − | − | − | − | Cl/Br | E | N |
| average, for site locations see | Jafr Basin | 2.74 | 0.612 | 0.105 | 69.08 | 25 | 267.09 | 97.84 |
| Fig. 1) | Azraq depression | 4.45 | 4.7 | 1.69 | 1069 | 240 | 333.11 | 138.08 |
| Deir Alla | 42.29 | 12.95 | 0.52 | 8118 | 192 | 206.49 | 168.97 | |
| Mafraq | 16.42 | 7.89 | 1.105 | 983.7 | 60 | 267.09 | 194.09 | |
| Irbid | 20.77 | 1.22 | 0.616 | 6155 | 296 | 231.39 | 217.79 |
| Sampling site | Br− | F − | I− | EC | Cl− | Cl/Br | # Sam. | N | E |
| W. Wala 1st set | 0.21–0.58 | 0.21–0.25 | 0.01–0.015 | 176–559 | 2.6–17.5 | 38 | 60 | 106 | 220 |
| W. Wala 2nd set | 0.26–0.34 | 0.204 | 0.005–0.01 | 140–225 | 7–16.1 | 38 | 42 | 106 | 220 |
| Daba’a | 0.025 | 0.08 | 0.006 | 123 | 52.2 | 210 | 3 | 101 | 222 |
| Thiban | 0.025 | 0.13 | 0.007 | 125 | 70 | 2800 | 3 | ||
| Thagrat El Jubb | 0.003 | 0.09 | 0.012 | 175 | 7.0 | 2333 | 2 | 168 | 255 |
| Mafraq | 0.002 | 0.10 | 0.015 | 158 | 7.35 | 3500 | 5 | 195 | 265 |
| Khalidiya | 0.014 | 0.123 | 0.014 | 239 | 17.5 | 1250 | 3 | 163 | 262 |
| Amman 7th circle | 0.040 | 0.435 | 0.001 | 148 | 16.1 | 402 | 2 | 148 | 233 |
| Safawi–Rweished | 0.00–0.01 | 0.10–0.13 | 0.005–0.008 | 194–225 | 5.25–12.3 | 800 | 2 | 205 | 403 |
| Azraq (Basalt) | 0.052 | 0.175 | 0.004 | 273 | 17.5 | 340 | 3 | 146 | 320 |
| Muwaqqar (dams) | 0.00–0.60 | 0.037–1.19 | 0.000–0.117 | 150–480 | 1.75–35.5 | 150 | 15 | 132 | 265 |
| Jordan River Baptism Site | 13–29 | NA | NA | 6010–9800 | 1740–2200 | 75–144 | 21 | 142 | 201 |
Granitic complex, Wadi Yutum
Groundwater here is found in the alluvial deposits of Wadi Yutum, along the main road connecting Quweira with Aqaba. The deposits consist merely of weathering products of the granitic basement building the surrounding mountains. The EC values of the groundwater range from 1000 to 1050 μS/cm, the Cl−, Br−, F− and I− concentrations from 200 to 215 mg/l, from 0.20 to 0.53 mg/l, from 1.4 to 1.7 mg/l and from 0.003 to 0.009 mg/l, respectively (Table 5). The Cl/Br ratios range from 400 to 1000 in comparison to sea water which is about 300. It seems that aerosols from the nearby Gulf of Aqaba are contributing to the salinity and halides contents of the groundwater in Wadi Araba.The contributions of the basement granitic complex and its weathering products to the Br− contents in Jordanian waters are quite small. This of course applies to the buried basement complex which underlies the whole territory of Jordan.
Disi-Ram water
This aquifer of Cambrian to Silurian age crops out in southern Jordan and is mainly composed of sandstones with some lime-stone beds. The replenishment to this aquifer’s water is very limited with an average groundwater age a few ten of thousand years. The salinity of the water in the recharge area in the southern part of Jordan and along the groundwater flow path northwards, to the latitude of the Dead Sea, at a distance of
| Table 4 Electrical conductivity (μS/cm), halides concentrations (mg/l), and chlorine to bromine | Wadi Name | Br− | F− | I− | EC | Cl− | Cl/Br | # Sam | N | E |
| mass ratios (Cl/Br) in the base | Klei’at | 1.21 | 0.57 | 0.014 | 680 | 73.5 | 61 | 4 | 215.9 | 208 |
| flow waters | Mashar’e | 1.24 | 0.35 | 0.016 | 681 | 289.5 | 233 | 4 | 199.5 | 207 |
| Maadi | 1.4 | 0.33 | 0.015 | 618 | 238.7 | 171 | 4 | 174.8 | 208.1 | |
| Kureima | 0.80 | 0.25 | 0.014 | 430 | 179.9 | 225 | 4 | 187.3 | 207.5 | |
| Hisban | 1.04 | 0.40 | 0.03 | 921 | 164.5 | 158 | 4 | 137 | 220 | |
| Fannoush | 1.97 | 0.36 | 0.02 | 547 | 215.6 | 109 | 4 | 171 | 208 | |
| Shueib | 1.09 | 0.32 | 0.014 | 456 | 50.8 | 47 | 4 | 145 | 209 | |
| Kafrain | 0.66 | 2.3 | 0.023 | 797 | 115.5 | 175 | 4 | 146 | 211 | |
| Yarmouk | 1.53 | 0.70 | 0.045 | 830 | 110.3 | 73 | 4 | 233 | 213 | |
| Arab | 1.46 | 0.54 | 0.034 | 780 | 104 | 72 | 4 | 236 | 220 | |
| Waqqas | 0.30 | 0.40 | 0.025 | 1160 | 87.5 | 289 | 4 | 215 | 209 | |
| Mujib | 1.03 | 0.81 | 0.042 | 1700 | 355 | 345 | 4 | 233 | 935 | |
| Wala | 0.65 | 0.98 | .028 | 1460 | 85.9 | 130 | 4 | 223 | 107 | |
| Hasa | 1.71 | 0.69 | NA | 1420 | 213 | 123 | 4 | 38 | 228 |
| Sampling site | Br− | F− | I− | EC | Cl− | Cl/Br | # Sam | N | E |
| Wadi Yutum | 0.20–0.53 | 1.4–1.7 | 0.003–0.009 | 1000–1050 | 200–215 | 400–1000 | 10 | 88.6 | 157.8 |
| Disi/Ram | 0.08–0.16 | 0.13–0.42 | 0.002 | 250–450 | 35–75 | ca. 400 | 32 | 88.3 | 205.9 |
about 200 km ranges from 250 to 550 μS/cm only. From this fact, it can be concluded that there is not much water/rock interactions and accordingly the release of salts into the water is quite limited. The Cl− content ranges from 35 to 80 mg/l and that of Br− from 0.08 to 0.16 mg/l. The Cl/Br ratio is around 400 compared to 300 for seawater. The F− content lies in the range for pure sandstone aquifers from 0.26 to 0.42 mg/l (Table 5).
Water in the Triassic and Jurassic rocks
Triassic rocks in Jordan consist of three units: a lower sandy unit, a central mainly limestone unit, and an upper unit deposited in a saline environment (Bandel and Salameh 2013). The overlying Jurassic rocks are near-shore sediments consisting of silt, marl and fluviatile, and ferruginous sands with evaporated beds and evaporated residues. Wells sunk in the Jurassic and Triassic rocks and springs emerging from these rocks produce water with high Br− concentrations ranging from 0.94 to 10.36 mg/l, with most concentrations of more than 5 mg/l (Table 6). The fluoride concentrations are also generally higher than for other waters in Jordan and range from 0.24 to 2.36 mg/l, but mostly they are slightly below 1 mg/l. The iodide concentrations are low and range from 0.001 to 0.16 mg/l. The EC of the water ranges from 1420 to 12,950 μS/cm with no obvious correlation with the concentration of Br−. The Cl/Br ratio is less than 110 in areas covered by Triassic rocks in Zara and Zerqa Ma’in increasing to 400 in areas covered by Triassic and Jurassic rocks in Abu Zigan and JICAWell No. 1. In the area between Zara and Zerqa Ma’in on the one side and Abu Zigan and JICAwell 1 on the other, in the areas of Rama, Hisban, and Kafrain, where it is unclear from which aquifer the water is produced or what mixing ratios the Triassic and Jurassic waters contributed, the Cl/Br ratios range from 100 to 300 mg/l.
Water in the Lower Cretaceous rocks
Lower Cretaceous rocks in Jordan (Kurnub Group) are composed of sandstone with intercalations of limestone and marl. The marine Kurnub to the north of Zerqa Ma’in latitude con- tains some evaporite residues with very thin (mm) intercala- tions of gypsum and halides. The groundwater in the Kurnub contains Br− in concentrations ranging from 0.37 to 1.04 mg/l. Most of the tested groundwater originated from the marine Kurnub which contains small amounts of evaporite residues. The EC values of the pure Kurnub water ranges widely from 474 to 3180 μS/cm without any clear correlation with Br− (Table 7). The Cl/Br ratio in the shallow Kurnub water ranges from 51 to 151, whereas that of the deep thermal water in the Kurnub along the Zerqa River, which may be affected by the underlying Jurassic and Triassic marine rocks, shows a Cl/Br ratio of 1250. It can be assumed here that NaCl was deposited from the brines leading to the deposition of the Triassic and
| Sampling site Br− F− I− EC | Cl− | Cl/Br | # Sam | N | E | ||||
| Zara | 3.5–5.1 | 0.29–0.48 | 0.011–0.026 | 1450–2250 | 320–515 | ca. 100 | 12 | 109.5 | 204.5 |
| Zarqa Ma’in | 3.2–7.7 | 0.24–0.52 | 0.06–0.14 | 2770–3140 | 560–816 | ca. 110 | 15 | 112 | 207 |
| JICA well 1 | 4.2 | 2.11 | 0.012 | 8550 | 1750 | 416 | 3 | 175 | 209.05 |
| Abu Zigan | 4.5–5.6 | 0.8–2.4 | 0.011–0.021 | 5810–12,570 | 1430–2760 | 318–493 | 5 | 178 | 211 |
| Rama w. | 2.5 | 1.6 | 0.018 | 5890 | 724 | 288 | 4 | 146 | 208.5 |
| Hisban w. | 0.95–9.1 | 0.30–0.93 | 0.011–0.16 | 5760–7075 | 910–1150 | 127–963 | 4 | 137 | 211.5 |
| Kafrain therm. w. | 5.1–10.4 | 0.91–0.95 | 0.012–0.16 | 6130–7680 | 929–1310 | 126–180 | 8 | 139.5 | 211 |
| Triassic and Jurassic springs | 3.9–4.6 | 1.05–1.2 | 0.014–0.025 | 3043–4490 | 472–564 | 102–144 | 3 | 177 | 215 |
| For locations, see Fig. 4 | |||||||||
| Sampling site | Br− | F− | I− | EC | Cl− | Cl/Br | # Sam | N | E |
| Shami well Baqa’a | 1.04 | 0.25 | 0.003 | 735 | 53.15 | 51 | 3 | 162 | 230 |
| Bahhath spring | 0.46 | 0.22 | 0.039 | 474 | 39.0 | 85 | 3 | 144 | 225 |
| Mahis spring | 0.55 | 0.17 | NA | 690 | 82 | 149 | 2 | 155 | 221 |
| For locations, see Fig. 4 |
Jurassic evaporite residues, where the rest of the brine con- taining Br− was flushed to the sea. The F− content is moderate and ranges from 0.11 to 0.27 mg/l and that of I− from 0.003 to 0.039 mg/l. As a conclusion, it is found that the Kurnub group as such can only contribute quite modest amounts of Br− to the groundwater. And this is only valid for the deep parts of the marine Kurnub affected by the underlying Jurassic and Triassic and eventually Permian deposits.
Water in the Upper Cretaceous rocks
Upper Cretaceous rocks in Jordan consist of alternating sediments of limestone, marl, shale, dolomitic limestone, chert, and phosphate. In the lower parts of the sequence, gypsum layers of up to 2 m in thickness are found, especially in the area of Wadi Mujib and south of it. The groundwater in the upper Cretaceous rocks along the highlands is renewable, and it generally flows in both east and west directions in the underground of the eastern plateau or to the Jordan-Dead Sea depression. The groundwater in these areas which has not mixed with the groundwater of other aquifers contains very low to moderate contents of bromide ranging from 0.001 to 1.5 mg/l with most samples containing less than 0.5 mg/l (Table 8). In areas where the aquifer is confined, along the northwestern slopes to the Jordan Valley, the Br− concentration is the highest in the aquifer water, generally with values ranging from 0.5 to 1.5 mg/l. The F− concentration ranges from 0.004 to 1.21 mg/l, whereas water in the confined aquifer has F− concentrations of more than 0.5 mg/l. The salinity of the groundwater ranges from 500 to 1100 μS/cm and the iodide concentrations are generally very low, of a few micrograms per liter. Only in the confined parts of the aquifer they increase to about 200 μg/l. The Cl/Br ratios in the unconfined parts of the aquifer are very high of a few 1000, whereas in the confined areas they range from 105 to 29. The confining layer of the upper Cretaceous aquifer is the Bituminous Marl unit containing high concentrations of bitumen.
Water in the phosphate rocks
Phosphate rocks in Jordan are widespread and cover extended land areas. Water levels in Jordan are generally deeper than 100 m. Therefore, phosphate rocks lie too shallow to lead to saturated water considering the deep groundwater tables of aquifers. However, rainwater infiltrates through phosphate rocks to reach the deep groundwater aquifers. Floodwaters resulting from rain events over areas covered by phosphates contain an average of 1.44 mg/l of Br−, 1.03 mg/l of F−, and 0.074 mg/l of I−. The EC value is 720 μS/cm, and the Cl/Br ratio is around 44 (Table 9). The Br− concentrations of two samples of the washing water of the phosphate mining processing were 1.83 and 7.9 mg/l. The F− concentration ranged from 1.44 to 9.55 mg/l and that of I− from 0.02 to 0.15 mg/l. The EC values
| Sampling site | Br− | F− | I− | EC | Cl− | Cl/Br | # Sam | N | E |
| Mukheiba (confined) | 0.70–1.10 | 0.40–0.51 | 0.09–0.19 | 633–820 | 20–66.8 | 29–90 | 16 | 233.95 | 213.83 |
| North Shuna (confined) | 0.94–1.46 | 0.56–1.21 | 0.03–0.14 | 966–1050 | 82.3–104 | 64–105 | 6 | 224.46 | 208.33 |
| Wadi Al Arab (confined) | 0.48–0.60 | 0.25–0.40 | 0.03–0.05 | 830–860 | 35.7–45.5 | 66–92 | 12 | 226.20 | 212.90 |
| Wadi Sir | 0.45 | 0.26 | < 0.004 | 649 | 29.8 | 66 | 3 | 150.64 | 228.47 |
| Ain Sara | 1.49 | 0.367 | 0014 | 880 | 72.1 | 48 | 2 | 66.69 | 216.67 |
| Rasoon, Teis, and Bahhath | 0.001–0.006 | 0.02–0.06 | <0.005 | 545–801 | 24.5–50.8 | >1000 | 6 | Springs along | the highlands |
| Yarout, Ibn Hammad, and Tafilah | 0.003–0.10 | 0.09–0,50 | <0.008 | 500–775 | 16–60.2 | >500 | 7 | ||
| For locations, see Fig. 4 |
| Sampling site Br− F− I− EC Cl− PO4 Cl/Br −3 | # Sam | N | E | |||||||
| Phosphate wash 1 | 1.83 | 9.55 | 0.02 | 3600 | 651 | 0.372 | 355 | 2 | 92.70 | 259.78 |
| Phosphate wash 2 | 1.44 | 7.50 | 0.15 | 4300 | 987 | 0.436 | 685 | 2 | 92.70 | 259.78 |
| Phosphate floodwater | 1.44 | 1.93 | 0.074 | 717 | 63 | 0.886 | 43.8 | 3 | 91.50 | 261.03 |
| Phosphate well (Maqqar, Amman) | 0.429 | o.31 | 0.001 | 680 | 28 | 0.583 | 65.3 | 5 | 152.32 | 239.98 |
were 3670 and 4300 μS/cm, and the Cl/Br ratios were 123 and 355. The groundwater in wells coming from the composite aqui- fer of phosphates and silicified limestone rocks had Br− and F− concentrations of 0.429 and 0.3 mg/l, respectively. The I− concentration was very low with 0.001 mg/l. The salinity is 680 μS/cm, and the Cl/Br ratio was 159. From these analyses, it becomes clear that phosphate rocks can contribute appreciable amounts of Br− and F− to surface and groundwater bodies.
Water in the Rijam (B4) and Shallala (B5) aquifer
The Rijam (B4) and Shallala (B5) aquifer consists of chalky limestone with chert beds and silicified limestone concretions. It covers areas in north Jordan along the hills overlooking the Yarmouk River and Lake Tiberias. Further east, it underlies the basalts of north Jordan. The Br−, F−, and I− concentrations in the groundwater of these aquifers range from: 0.05 to 0.49, from 0.05 to 0.3, and from 0.001 to 0.021 mg/l, respectively (Table 10). The salinity of the water, relative to other groundwater in Jordan, is low and is the result of direct recharge by precipi- tation water, fast flow, and discharge mechanisms. The Cl/Br rations are around 100. As a conclusion, it can be stated here that the contributions of the Rijam and Shallala aquifer to the Br−, F−, and I− contents of groundwater are very limited. This can be interpreted as a result of the exposure of the aquifer at ground surface, its perched water type, and its strong leaching as a porous and highly permeable aquifer cropping out in a high rainfall area.
Water in the Lisan Formation
Analyses were performed on water samples collected from wells and springs in the Lisan Marls especially from the area of Karama in the course of the Karama dam site investigations (Gibb 1993). The results of analyses are listed in Table 11. Each site was sampled more than once and therefore, values are given within ranges. The analyses show that the salinities of the Lisan water are very high 44,190–49,000 μS/cm (springs). When diluted with other water sources, it decreases to around 9000 μS/cm as is found in the water flowing together from different springs (Table 11). The Br− concentration of the Lisan water is around 415 mg/l decreasing in the mixed water to 41 to 67 mg/l. The artesian flowing water has EC and Br− values between the pure Lisan Marl water and the diluted spring water of 22, 500–28,500 μS/cm and 110–188, respectively. The Cl/Br ratio of the Lisan water ranges from 48 to 50 which is very close to that of the Dead Sea water of 42. When mixed with other less saline waters, the Cl/Br ratio increases gradually to 108 in the artesian flowing water and to 117 in the water flowing together from different springs with an EC value of 9000 μS/cm. Leached Lisan Marl samples, 200 g in 1 L distilled water, for 24 h resulted in EC values of 9560–33,230 μS/cm in four tested samples with resulting Cl/Br ratios of 48–63 increasing with decreasing salinity as a result of mixing with more fresh water originating from other groundwater bodies (Table 12). The F− concentrations show decreasing values with increasing water salinity. The very saline Lisan water has F− concentrations of 0.20–0.25 mg/l increasing by mixing with other waters gradually to 0.9–2.3 mg/l. The leached Lisan Marl samples released 0.15–0.26 mg/l of F−, concentrations resembling those of the very saline groundwater in the Lisan Formation.
| Sampling site Br− F− EC | Cl− | Cl/Br | # Sam | N | E | |||
| Karama dam groundwater | 413–415 | 0.20–0.25 | 44,190–49,000 | 20,056–20,361 | 48–50 | 5 | 155.47 | 203.86 |
| Artesian borehole KB34 | 110–188 | 0.78–1.95 | 22,500–28,500 | 8886–10,081 | 48–108 | 3 | 157 | 202 |
| Mixture of spring waters | 41–67 | 0.92–2.30 | 9000–18,750 | 3035–6900 | 74–117 | 5 | 157 | 201.8 |
Thermal water
Thermal springs emerge along the eastern slopes to the Dead Sea and the Jordan River. Their discharge temperatures range from 35 °C in Weda’a spring (southwest of Karak) to 64 °C in some Zara springs. But, generally, the majority ranges between 45 and 58 °C. The southern springs of Afra, North of Tafilah city; Weda’a, southwest of Karak city; and Ibn Hammad, northwest of Karak city have relatively low salinities ranging from 510 to 842 μS/cm and Br− concentrations of 0.471 to 1.1 mg/l (Table 13). The F− and I− concentrations range from 0.20 to 0.62 and from 0.001 to 0.009 mg/l, respectively. The ratios Cl/Br range from 86 to 260. To the north of Wadi Ibn Hammad, the salinity of the water increases gradually as a result of intercalations of Triassic and Jurassic rocks containing residues of evaporites between the deep Disi and Ram aquifer rocks of Cambrian to Silurian age and the lower Cretaceous Kurnub sandstone rocks. The Br− concentrations increase simultaneously with increasing salinity and range between 2.8 and 9.5 mg/l. The F− concentration, with the exception of Hamman spring in north Jordan at the Yarmouk River, ranges from 0.2 to 0.72 mg/l, which is not much different of that of the southern springs of Afra, Weda’a, and Ibn Hammad. The I− concentrations range from 0.05 to 0.23 mg/l which is higher than that of the southern springs. This indicates that the intercalations of Triassic and Jurassic rocks in the area north of Mujib and south of Zerqa Ma’in is contributing to the Br− and I− contents of the water, but not to its F− content. The Cl/Br ratios in the northern springs are generally lower than those in the southern springs with 50 to 150.It seems that Jurassic, Triassic, and Permo-Triassic rocks which contain residues of evaporites are the source of high Br− and I− in the thermal spring water, especially because the concentrations of these halides, in those areas in which no Jurassic, Triassic, and Permo-Triassic rocks are found south of Mujib area, the contents of bromide and iodide are low and the Cl/Br ratios are higher than those found in the Jurassic, Triassic, and Permo-Triassic waters.
Basalt water
Basalts cover in north Jordan around 11 % of the territory of Jordan. They erupted in many phases extending from Neogene to the Holocene. The EC values range from 360 to 4770 μS/cm (Table 14). The Br− concentration in the basalt aquifer water ranges from a few tens of micrograms per liter up to around 1 mg/l with the majority of samples having concentrations less than 200 μg/l. The F− concentration ranges from a few micrograms per liter up to 518 μg/l and I− concentration from 1 μg/l up to 66 μg/l. The ratio is very high >1000:1. It seems that the Br− content of the groundwater in the Basalt Aquifer does not form a main source for Br− in the waters of Jordan. This also means that the volcanic activity, which exhales HBr, HF, and HI is no more producing such gases, and the existing basalts are not contributing in any way to the concentrations of Br−, F−, and I− in the water resources in Jordan. Historically, during the eruption phases and immediately after that, volcanic activities might have contributed with large amounts of Br− and F− to the Dead Sea as an exitless lake and base level for the major surface and groundwater sources for areas covered with volcanic rocks.
| Sampling site | Br− | F− | I− | EC | Cl− | Cl/Br | # Sam | N | E |
| Himma | 2.50–4.67 | 0.37–0.20 | 0.05–0.14 | 1280–1500 | 196–250 | 50–80 | 9 | 233.07 | 213.85 |
| Abu Thableh | 2.81–4.62 | 0.52–0.61 | 0.020–0.042 | 1880–1940 | 301–333 | 71–107 | 4 | 196.30 | 205.13 |
| Abu Zigan, Deir Alla | 4.5–5.6 | 0.8–2.36 | 0.011–0.021 | 5810–12,570 | 1430–2760 | 318–493 | 5 | 177.45 | 210.08 |
| Zara | 3.51–5.14 | 0.29–0.48 | 0.011–0.026 | 1450–2250 | 320–515 | ca. 100 | 5 | 113.71 | 205.17 |
| Zarqa Ma’in | 3.2–7.7 | 0.24–0.52 | 0.06–0.14 | 2770–3140 | 560–816 | ca. 110 | 15 | 123.54 | 219.04 |
| Ibn Hammad | 0.47–0.74 | 0.35–0.50 | 0.002–0.009 | 1380–1530 | 293–349 | 83–102 | 12 | 79.00 | 209.76 |
| Weeda’a | 0.92–1.1 | 0.50–0.62 | NA | 510–574 | 195–220 | 212–218 | 8 | 73.89 | 203.91 |
| Afra | 0.68–0.79 | 0.20–0.35 | 0.001–0.002 | 545–586 | 58–78 | 85–99 | 10 | 36.16 | 211.09 |
| Zerqa River Therm. | 5.5–6.0 | 1.1–1.17 | 0.08–0.09 | 3150–3450 | 487–492 | 82–88 | 4 | 180.4 | 235.5 |
Institute at Karlsruhe Institute of Technology by Prof. Dr. Fritz Frimmel and Dr. Gudrun Abbt-Braun. The results are listed in Tables 15 and 16 which shows the high concentrations of Br−, F−, and Cl− released from these rock types once leached with distilled water for a few hours. The high discrepancy in the concentrations of Cl and Br between the analyzed samples in the two laboratories refers to the different weights of samples dissolved in a water quantity. In Karlsruhe, ca. 10 g of rock sample was dissolved in 20 to 66 ml of distilled water, whereas for those samples analyzed at the University of Jordan 1 g of rock was dissolved in 100 ml of distilled water. F course of interest here are the Cl/Br ratios and the released concentrations of Br. The grinding of the three rock samples resulted in grain sizes that were differently distributed as a result of the rock sample textures. The phosphate rock sample composed of chert is very hard, and the grinded sample consisted of somehow homogeneous grain sizes as a result of grinding, from which surfaces salts were dissolved. The Triassic/Jurassic sample consists of silt, which upon grinding resulted in homogeneous silt grains composed of quartz in addition to the grinded cementation matter, from which salts were dissolved. The oil shale sample consists of shale which upon grinding resulted in very fine grains with huge surface areas of grains containing the salts which were dissolved and released into the added water. The effects of grinding on the grain size distribution of the different rock types explain the concentrations of the released ions (Tables 15 and 16). The ratios of Cl/Br in the oil shale leachates are lower than that of the Dead Sea water of 42, which may indicate that Br− is concentrated in the organic matter and not only in the inorganic. The Cl/Br ratios of the Jurassic and Triassic rocks and gypsum deposits of 102–262 are lower than that of seawater of 300 indicate at higher contents of Br− relative to Cl− than in seawater, which means contributions of Br− from organic matter in the leachates. Phosphate rocks contribute also with small amounts of Br− to the water resources, but the Cl/Br ratio remains far higher than that of seawater, resembling water of limestone aquifers. The Lisan Formation contributes high amounts and concentrations of both Br− and Cl− to the water resources in the Jordan Valley area and the Cl/Br ratios range from 24 to 51 which is partly lower than that of the Dead Sea of 42 and partly slightly higher.
