Arab J Geosci (2016) 9:414 DOI 10.1007/s12517-016-2431-9
ORIGINAL PAPER
Origin of high bromide concentration in the water sources in Jordan and in the Dead Sea water Elias Salameh 1 & Arwa Tarawneh 1 & Marwan Al-Raggad 2
Received: 20 August 2015 / Accepted: 9 March 2016 # Saudi Society for Geosciences 2016
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 evaporate salts
* Elias Salameh
[email protected] Arwa Tarawneh
[email protected] Marwan Al-Raggad
[email protected]
1
Faculty of Science, University of Jordan, Amman 11942, Jordan
2
Water, Energy and Environment Research Center, University of Jordan, Amman 11942, Jordan
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 . Dead Sea . Triassic rocks . Oil shale . Phosphate . Lisan Formation
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; Bender 1968; 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
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seas would have received their water from similar sources as the ocean. In Jordan, many surface and groundwater resources 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-Zir 1989). 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 is not 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 beyond 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 northeasterly 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 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 graben 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 concentration of evaporates (Bender 1968; Bandel and Salameh 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 waterbearing sediment sequence in Jordan, consisting of sandstones
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Fig. 1 Generalized geological map of Jordan showing the main strategraphic systems, based on MoWI Open files
and quartzite. It crops out only in the southern part of Jordan and along Wadi Araba–Dead Sea Rift Valley and underlies the entire area of Jordan (NWMP 1977). The southern part of the complex forms the fresh water 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). The Kurnub–Zerqa aquifer system is being exploited mainly in the lower Zerka River catchment and in the Baqa’a areas. The direction of groundwater flow in this aquifer system is generally towards the west; towards the northeast in the
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Fig. 2 Strategraphy 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.
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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 A4 aquifer, 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
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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.
It consists of two main systems: A. Basalt aquifer Basalts extend from the Syrian Jabel Arab-Druz area southward 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
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 the last 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 base flows, groundwater, and precipitation water lie generally in remote areas, far away from development centers with industrialization and
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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 1 month’s periods was collected from each station and analyzed for the major constituents and the different halogens. In the Jordan University station, each precipitation 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 centimeters 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, semiarid, 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 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
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Fig. 3 General location map, cities, and other relevant localities in Jordan
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 to12.89 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.
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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 Jordan Valley were 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,
Arab J Geosci (2016) 9:414 Table 1 Electrical conductivity (μS/cm), halides concentrations (mg/l), and the chlorine to bromine (Cl/Br) mass ratios in precipitation water in Jordan (results of 3 years sampling and analyses with a minimum of 10 samples but generally more than 17 samples from each site. For site locations see Fig. 1)
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Rainfall station
Br−
F−
I−
EC
Cl−
Cl/Br
E
N
University of Jordan, Amman Ruseifa Khalidiya Azraq Rabba
0.049 0.113 0.226 0.17 0.575
0.047 0.060 0.038 0.097 0.050
0.01 0.008 0.010 0.074 0.022
75.6 136.4 165.1 272.7 114.3
9.03 9.62 11.69 23.38 13.93
183 84.9 51.7 137.5 24.3
232.42 249.79 272.50 326.07 220.10
158.47 159.19 176.20 145.68 75.51
Shoubak Salt Irbid Town Irbid weather station Uni. Farm Deir Alla, J. Valley Queen Alia Int’l Airport Muwaqqar
0.341 0.066 0.021 0.016 0.315 0.093 0.129
0.079 0.039 0.042 0.018 0.099 0.055 0.081
0.007 0.006 0.019 0.038 0.014 0.029 0.013
96.5 98.7 95.2 192 159.8 206 165
9.77 14.77 8.02 18.90 16.56 72.10 17.68
28.6 223 381 120 52.6 775 137
208.98 218.69 230.20 229.44 206.46 246.27 255.09
−7.69 160.51 218.85 218.65 170.29 126.60 136.65
Safawi–Rweished, and Azraq range between 0.012 and 0.44 mg/l and between <0.0001 and 0.11 mg/l, respectively. The EC values of floodwater of wadis draining only flood flows are less than 250 μS/cm in general. But at the beginning of a flood event, the EC values may reach 500 μS/cm as a result of overland flow and dissolution of salt crusts forming at the top soils during the dry season. In the Jordan River water, the EC values range from 6010 to 9800 μS/cm, reflecting the mixing of flood and base flow waters. The Cl/Br ratios in desert wadis draining only floodwater are very high and exceed 400 and in wadis 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 75 to 144. Base flow 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
Table 2 Halides inputs in the dry deposition (mg/m2/year) in different areas in Jordan (1-year average, for site locations see Fig. 1)
& &
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 catchment area, to 340 in Wadi Mujib, but most of the base flows show ratios of less than 300 and higher than 75.
Sampling site
Br−
F−
I−
Cl−
Cl/Br
E
N
Jafr Basin Azraq depression Deir Alla Mafraq Irbid
2.74 4.45 42.29 16.42 20.77
0.612 4.7 12.95 7.89 1.22
0.105 1.69 0.52 1.105 0.616
69.08 1069 8118 983.7 6155
25 240 192 60 296
267.09 333.11 206.49 267.09 231.39
97.84 138.08 168.97 194.09 217.79
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Table 3 Electrical conductivity (μS/cm), halides concentrations (mg/l), and chlorine to bromine mass ratios (Cl/Br) in floodwaters (in cases of too many measurements a range of concentrations is given) Sampling site
Br−
F−
I−
EC
Cl−
Cl/Br
# Sam.
N
E
W. Wala 1st set W. Wala 2nd set Daba’a Thiban
0.21–0.58 0.26–0.34 0.025 0.025
0.21–0.25 0.204 0.08 0.13
0.01–0.015 0.005–0.01 0.006 0.007
176–559 140–225 123 125
2.6–17.5 7–16.1 52.2 70
38 38 210 2800
60 42 3 3
106 106 101
220 220 222
Thagrat El Jubb Mafraq Khalidiya Amman 7th circle Safawi–Rweished Azraq (Basalt) Muwaqqar (dams) Jordan River Baptism Site
0.003 0.002 0.014 0.040 0.00–0.01 0.052 0.00–0.60 13–29
0.09 0.10 0.123 0.435 0.10–0.13 0.175 0.037–1.19 NA
0.012 0.015 0.014 0.001 0.005–0.008 0.004 0.000–0.117 NA
175 158 239 148 194–225 273 150–480 6010–9800
7.0 7.35 17.5 16.1 5.25–12.3 17.5 1.75–35.5 1740–2200
2333 3500 1250 402 800 340 150 75–144
2 5 3 2 2 3 15 21
168 195 163 148 205 146 132 142
255 265 262 233 403 320 265 201
# Sam. number of samples, NA not analyzed
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. Table 4 Electrical conductivity (μS/cm), halides concentrations (mg/l), and chlorine to bromine mass ratios (Cl/Br) in the base flow waters
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 limestone 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
Wadi Name
Br−
F−
I−
EC
Cl−
Cl/Br
# Sam
N
E
Klei’at Mashar’e Maadi Kureima Hisban Fannoush Shueib Kafrain Yarmouk Arab Waqqas Mujib Wala Hasa
1.21 1.24 1.4 0.80 1.04 1.97 1.09 0.66 1.53 1.46 0.30 1.03 0.65 1.71
0.57 0.35 0.33 0.25 0.40 0.36 0.32 2.3 0.70 0.54 0.40 0.81 0.98 0.69
0.014 0.016 0.015 0.014 0.03 0.02 0.014 0.023 0.045 0.034 0.025 0.042 .028 NA
680 681 618 430 921 547 456 797 830 780 1160 1700 1460 1420
73.5 289.5 238.7 179.9 164.5 215.6 50.8 115.5 110.3 104 87.5 355 85.9 213
61 233 171 225 158 109 47 175 73 72 289 345 130 123
4 4 4 4 4 4 4 4 4 4 4 4 4 4
215.9 199.5 174.8 187.3 137 171 145 146 233 236 215 233 223 38
208 207 208.1 207.5 220 208 209 211 213 220 209 935 107 228
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Table 5 Electrical conductivity (μS/cm), halides concentrations (mg/l), and chlorine to bromine mass ratios (Cl/Br) in Wadi Yutum and Disi-Ram aquifers waters Sampling site
Br−
F−
I−
EC
Cl−
Cl/Br
# Sam
N
E
Wadi Yutum Disi/Ram
0.20–0.53 0.08–0.16
1.4–1.7 0.13–0.42
0.003–0.009 0.002
1000–1050 250–450
200–215 35–75
400–1000 ca. 400
10 32
88.6 88.3
157.8 205.9
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).
in Zara and Zerqa Ma’in increasing to 400 in areas covered by Triassic and Jurassic rocks in Abu Zigan and JICA Well No. 1. In the area between Zara and Zerqa Ma’in on the one side and Abu Zigan and JICA well 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 Triassic and Jurassic rocks
Water in the Lower Cretaceous 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
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 contains some evaporite residues with very thin (mm) intercalations 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
Table 6 Electrical conductivity (μS/cm), halide concentrations (mg/l), and chlorine to bromine mass ratios (Cl/Br) in the Triassic and Jurassic groundwater (in cases of too many measurements, a range of concentrations is given) Sampling site
Br−
F−
I−
EC
Cl−
Cl/Br
# Sam
N
E
Zara Zarqa Ma’in JICA well 1 Abu Zigan Rama w. Hisban w. Kafrain therm. w. Triassic and Jurassic springs
3.5–5.1 3.2–7.7 4.2 4.5–5.6 2.5 0.95–9.1 5.1–10.4 3.9–4.6
0.29–0.48 0.24–0.52 2.11 0.8–2.4 1.6 0.30–0.93 0.91–0.95 1.05–1.2
0.011–0.026 0.06–0.14 0.012 0.011–0.021 0.018 0.011–0.16 0.012–0.16 0.014–0.025
1450–2250 2770–3140 8550 5810–12,570 5890 5760–7075 6130–7680 3043–4490
320–515 560–816 1750 1430–2760 724 910–1150 929–1310 472–564
ca. 100 ca. 110 416 318–493 288 127–963 126–180 102–144
12 15 3 5 4 4 8 3
109.5 112 175 178 146 137 139.5 177
204.5 207 209.05 211 208.5 211.5 211 215
For locations, see Fig. 4
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Table 7 Electric conductivity (μS/cm), halides concentrations (mg/l), and chlorine to bromine mass rations (Cl/Br) in the Lower Cretaceous rocks (Kurnub groundwater)
Sampling site
Br−
F−
I−
EC
Cl−
Cl/Br
# Sam
N
E
Shami well Baqa’a Bahhath spring Mahis spring
1.04 0.46 0.55
0.25 0.22 0.17
0.003 0.039 NA
735 474 690
53.15 39.0 82
51 85 149
3 3 2
162 144 155
230 225 221
For locations, see Fig. 4
Jurassic evaporite residues, where the rest of the brine containing 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
Table 8 Electric conductivity (μS/cm), halogen concentrations (mg/l), and chlorine to bromine mass ratios (Cl/Br) in the Upper Cretaceous aquifer water (in cases of too many measurements, a range of concentrations is given) Sampling site
Br−
F−
I−
EC
Cl−
Mukheiba (confined) 0.70–1.10 0.40–0.51 0.09–0.19 633–820 20–66.8 North Shuna (confined) 0.94–1.46 0.56–1.21 0.03–0.14 966–1050 82.3–104 Wadi Al Arab (confined) 0.48–0.60 0.25–0.40 0.03–0.05 830–860 35.7–45.5 Wadi Sir 0.45 0.26 < 0.004 649 29.8 Ain Sara 1.49 0.367 0014 880 72.1 Rasoon, Teis, and Bahhath 0.001–0.006 0.02–0.06 <0.005 545–801 24.5–50.8 Yarout, Ibn Hammad, and Tafilah 0.003–0.10 0.09–0,50 <0.008 500–775 16–60.2 For locations, see Fig. 4
Cl/Br 29–90 64–105 66–92 66 48 >1000 >500
# Sam 16 6 12 3 2 6 7
N
E
233.95 213.83 224.46 208.33 226.20 212.90 150.64 228.47 66.69 216.67 Springs along the highlands
Arab J Geosci (2016) 9:414 Table 9 water
Page 13 of 20 414
Electrical conductivity (μS/cm), halides and phosphate concentrations (mg/l), and chlorine to bromine mass ratios (Cl/Br) in the phosphate
Sampling site
Br−
F−
I−
EC
Cl−
PO4−3
Cl/Br
# Sam
N
E
Phosphate wash 1 Phosphate wash 2 Phosphate floodwater Phosphate well (Maqqar, Amman)
1.83 1.44 1.44 0.429
9.55 7.50 1.93 o.31
0.02 0.15 0.074 0.001
3600 4300 717 680
651 987 63 28
0.372 0.436 0.886 0.583
355 685 43.8 65.3
2 2 3 5
92.70 92.70 91.50 152.32
259.78 259.78 261.03 239.98
were 3670 and 4300 μS/cm, and the Cl/Br ratios were 123 and 355. The groundwater in wells coming from the composite aquifer 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 precipitation 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.
Table 10 Electrical conductivity (μS/cm), halides range of concentrations (mg/l), and chlorine to bromine mass ratios (Cl/Br) in the Rijam and Shallala aquifer water (sampling sites Yarmouk southern side) Sampling site (samples n = 12)
Br−
F−
I−
EC
Cl−
Cl/Br
# Sam
Quelba, Turab, and Shallala Sps.
0.05–0.49
0.05–0.30
0.001–0.021
450–706
14–40
ca. 100
11
Locations: Head waters of wadi Arab and Yarmouk in Jordan
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Table 11 Electrical conductivity (μS/cm), halides range of concentrations (mg/l), and chlorine to bromine mass ratios (Cl/Br) in the Lisan Formation water (6–10 samples from each site) Sampling site
Br−
F−
EC
Cl−
Cl/Br
Karama dam groundwater Artesian borehole KB34 Mixture of spring waters
413–415 110–188 41–67
0.20–0.25 0.78–1.95 0.92–2.30
44,190–49,000 22,500–28,500 9000–18,750
20,056–20,361 8886–10,081 3035–6900
48–50 48–108 74–117
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. Table 12 Electrical conductivity (μS/cm), halides range of concentrations (mg/l), and chlorine to bromine mass ratios (Cl/Br) in the leached Lisan Formation rock samples in distilled water after 24 h Sample no.
Br−
F−
EC
Cl−
Cl/Br
N
E
Lisan 1 Lisan 2 Lisan 3 Lisan 4
140 74 168 242
0.15 0.24 0.26 0.82
15,650 9560 18,900 33,230
6640 4665 8938 12,260
48 63 53 51
158.74 159.80 49.23 47.84
203.74 200.90 193.55 193.38
# Sam 5 3 5
N
E
155.47 157 157
203.86 202 201.8
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 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 exit less lake and base level for the major surface and groundwater sources for areas covered with volcanic rocks.
Leaching testes of oil shale, phosphate, and Jurassic Triassic rock samples Leaching tests were carried out on rock samples collected from the major outcrops of oil shales, phosphates, Jurassic/ Triassic rocks and gypsum deposits and limestone of Upper Cretaceous rocks. The analyses were carried out in the laboratories of the University of Jordan and in Engler-Bunte
Arab J Geosci (2016) 9:414 Table 13
Page 15 of 20 414
Electrical conductivity (μS/cm), halides concentrations (mg/l), and chlorine to bromine mass ratios (Cl/Br) in the thermal spring water
Sampling site
Br−
F−
I−
EC
Cl−
Cl/Br
# Sam
N
E
Himma Abu Thableh Abu Zigan, Deir Alla Zara Zarqa Ma’in Ibn Hammad Weeda’a Afra Zerqa River Therm.
2.50–4.67 2.81–4.62 4.5–5.6 3.51–5.14 3.2–7.7 0.47–0.74 0.92–1.1 0.68–0.79 5.5–6.0
0.37–0.20 0.52–0.61 0.8–2.36 0.29–0.48 0.24–0.52 0.35–0.50 0.50–0.62 0.20–0.35 1.1–1.17
0.05–0.14 0.020–0.042 0.011–0.021 0.011–0.026 0.06–0.14 0.002–0.009 NA 0.001–0.002 0.08–0.09
1280–1500 1880–1940 5810–12,570 1450–2250 2770–3140 1380–1530 510–574 545–586 3150–3450
196–250 301–333 1430–2760 320–515 560–816 293–349 195–220 58–78 487–492
50–80 71–107 318–493 ca. 100 ca. 110 83–102 212–218 85–99 82–88
9 4 5 5 15 12 8 10 4
233.07 196.30 177.45 113.71 123.54 79.00 73.89 36.16 180.4
213.85 205.13 210.08 205.17 219.04 209.76 203.91 211.09 235.5
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 is referred 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 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 differently distributed grain sizes 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 Table 14
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.
Areas with high bromide concentrations in groundwater In three, wide areas in Jordan, high Br− concentrations are found in the groundwater. These areas are:
Electrical conductivity (μS/cm), halides concentrations (mg/l), and chlorine to bromine mass ratios (Cl/Br) in the basalt aquifer groundwater
AWSA wells
Br−
F−
I−
EC
Cl−
Cl/Br
# Sam
N
E
Azraq
0.01–0.02
0.21–0.518
0.01–0.021
400–896
68.5–166
>1000
3
148.50
321.30
Soda sp. Ora sp. Mustadama sp. Northern Badiya Hallabat Dhuleil Basalt sp./Syria Sabha
0.003 0.02–0.6 0.197 0.012–0.47 0.14–0.47 0.13–1.05 0.05–0.07 0.008–0.06
0.32 0.33 0.33 0.017–0.20 0.00–0.003 0.01–0.017 0.01–0.05 0.024–0.38
0.029 0.026 0.029 0.005–0.009 0.001–0.002 0.02–0.066 0.001–0.002 0.001
1600 733 1530 735–1450 435–1300 2960–4770 348–360 496–870
357 119 337 107–274 61–291 749–1246 29–36 41–124
>1000 200 to >1000 >1000 400–>1000 300–>1000 >1000 >1000 >1000
6 5 5 6 5 7 5 3
139.05 144.25 143.85 179.32 165.66 171.25 192.71 148.50
322.50 323.20 323.70 323.40 279.27 270.14 291.94 321.30
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Table 15 Bromide, fluoride, and chloride concentrations (mg/l) and chlorine to bromine mass ratios (Cl/Br) in the leached phosphate, Jurassic/Triassic and oil shale rock samples in distilled water (calculated
from the results of analyses performed at Karlsruhe Institute of Technology; Prof. Fritz Frimmel and Dr. Gudrun Abbt-Braun)
Rock type
Br−
F−
Cl−
Cl/Br
N
E
Oil shale: deep Jurassic/Triassic rocks Jurassic/Triassic gypsum
0.019 0.359 3.30
0.06 0.001 0.002
0.64 42.0 833.7
33.7 116.6 252
69.23 176.69 177.13
231.85 216.07 217.18
& & &
South of Amman to Karak; the area along the highlands Wadi Araba area; south of the Dead Sea along the northern part of Wadi Araba Adasiya area, south of the Yarmouk River course in the Jordan Valley area and along the eastern bank of the Jordan River covered by the Lisan Marl Formation
South of Amman to Karak area Groundwater in this area is characterized by relatively low EC values ranging from 628 to 1840 μS/cm (Tables 17 and 18), which indicate moderate water rock interactions of infiltrated rainwater with the country rocks mainly composed of carbonates. The Br− concentrations range from 0.44 to 9.60 mg/l with the majority of wells having concentrations of around 1–2 mg/l. The F− concentrations and range from 0.47 to 1.38 mg/l with the majority of wells having concentrations of around 0.3 mg/l. The Cl/Br ratios are relatively low in the groundwater in the surroundings of the Queen Alia airport area ranging from 72 to 193. But in the Sultani Qatranah area, they are still lower ranging from 33 to 126 with the majority of wells having ratios of around 80. Compared to oceanic water with a ratio of 300 and Dead Sea water with 42, this indicates high contributions of Br− from the country rocks composed of phosphates and oil shales to the groundwater of that area and hence to the Dead Sea water. To the south of Queen Alia airport, in Sultani and Qatranah sub-areas covered with Muwaqqar Oilshale Formation, the ratios Cl/Br are lower than those found in the airport
Table 16 Bromide and chloride concentrations (mg/kg) and chlorine to bromine mass ratios (Cl/Br) in the leached phosphate, Jurassic/Triassic rocks and gypsum deposits, and oil shale rock samples in distilled water
surroundings, and are very low compared to oceanic water of 300 and in general a little higher than those of the Dead Sea water of 42, indicating the very high contributions of the country rocks composed of oil shale and phosphates. The higher Br concentrations and the lower Cl/Br ratios in the southern part of the area compared with the northern part are attributed to strong leaching of the Bituminous Marl in the southern part than in the northern part of the area. Wadi Araba area south of the Dead Sea The groundwater in this area is found in the alluvial deposits and other recent sediments. The EC values of the water range from 584 to 7200 μS/cm (Table 19), but generally, most wells produce brackish water of more than 2000 μS/cm (Abu Zir 1989). The Br− concentrations range from 2.4 to 50.7 mg/l which are fairly high concentrations relative to the salinity of the water. The F− concentrations range from 1.06 to 3.15 mg/l, but are generally around 2 mg/l. The I− concentrations are also slightly elevated compared to other waters with a few tens of micrograms per liter. The Cl/Br ratios are very low and very close to those of the Dead Sea water, ranging from 6.07 to 273 but are generally between 50 and 70. In this area of Wadi Araba, two explanations are possible for the high Br− contents of the groundwater: 1. Dissolution of salts from the Lisan Formation covering part of the area or flushing of residual water in the aquifer which filled that aquifer during former stages when the
Rock type
Br−
Cl−
Cl/Br
# of samples
N
E
Phosphate and Apatite Jurassic/Triassic rocks Jurassic/Triassic gypsum Oil shale: shallow Oil shale: deep Lisan
4.5 10.6 4.4 14.2 22.6 495–540
3430 2778 449 463 812 12,270–16,350
764 262 102 32.6 36 24–51
2 2 3 2 2 4
160.32 176.69 177.13
224.54 216.07 217.18
160.32 224.54 Lisan Formation
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Table 17 Electrical conductivity (μS/cm), halides concentrations (mg/ l), and chlorine to bromine mass ratio (Cl/Br) in the high bromide waters (Sultani–Qatranah–Karak area, three samples from each site) Sampling site
Br−
F−
EC
Cl−
Magara Lajjun 19 Lajjun 10 Lajjun 6 Qatranah 16 Qatranah 12 and 14 Qatranah 8 Qatranah 1 Qatranah 3
2.15 1.27 9.60 1.43 1.97 2.78 4.77 4.22 2.68
0.480 0.79 1.20 0.88 0.92 0.88 0.90 0.79 0.86
1020 755 1480 988 1140 1190 1840 1620 1190
182 84.6 66.5 52.3 70.16 234.85 336 33 69.78 233.03 175 122 67.70 227.50 250 126.8 76.78 249.81 207 74.5 75.90 249.60 393 83 74.60 249.39 196 46.5 72.80 249.03 250 93.2 72.47 248.26
Sultani West Sultani S44 Sultani S83
3.57 1.40 3.44 1.38 2.52 0.73
1160 149 1440 249 1340 258
Cl/Br N
42 72.2 102
E
56.75 246.14 57.16 247.10 55.15 247.35
Dead Sea before about 11,000 years extended some 45 km to the south of its recent shore. 2. Dissolution and flushing of phosphate and oil shale deposits of the highlands along fault zones oriented in an approximate east-west direction towards Wadi Araba. Jafr basin, which lies along the highland, had formed from a gulf area of the ancient Tethys extending in an ESE-WNW direction. The western area bordering Wadi Araba was then uplifted in the course of the formation of the Jordan Rift Valley. But it seems that the deep groundwater of the Jafr basin and of the Hasa region which lies northwest of Jafr is still moving westwards towards Wadi Araba, recharging the alluvial aquifers there. The groundwater which reaches Wadi Araba from the Jafr and Hasa basins has been in contact with the oil shale and phosphate rocks underlying these areas for many tens of thousands to many hundreds of thousands of years. These long contact times must have enhanced the dissolution of Br− enhanced by the organic and inorganic constituents of the oil shale and phosphatic rocks.
Table 18 Electrical conductivity (μS/cm), halides concentrations (mg/ l), and chlorine to bromine mass ratio (Cl/Br) in the groundwater of the area around Amman International Airport (three samples from each site) Sampling site
Br−
F−
EC
Cl−
Hakam El-Fayez Mut. Sattel S.R. Zabn Dr. Ghuneim Mashhour El-Fayez Majed El-Fayez
0.44 0.94 2.74 0.94 1.27 1.05
0.50 0.91 1.01 1.15 0.79 1.36
875 59.2 135 132.30 242.80 1326 77.7 82.7 – – 1085 267.0 97.4 137.09 238.86 1635 172.0 193 – – 628 205.2 162 133.68 234.26 850 75.4 72 131.20 233.29
Cl/Br N
E
Table 19 Electrical conductivity (μS/cm), halides concentrations (mg/ l), and chlorine to bromine mass ratio (Cl/Br) in the high bromide waters of wadi Araba (two to four samples for each site) Sampling site/ well no.
Br−
F−
I−
EC
Cl−
Cl/Br
UM 6 UM 3 Um 4 WM 3 F5 WM 1 WM 7 WM 13 40 RJ WS 2 R1 EO W 16 EO W 4 EO W14
14.9 8.21 5.34 19.7 17.4 11.5 14.5 20.6 5.8 6.94 5.47 5.56 50.7 5.1
1.8 1.56 2.3 1.9 1.43 1.21 2.24 1.02 2.87 2.44 2.9 2.73 1.19 3.15
0.025 0.039 0.095 0.086 0.007 0.18 0.11 0.086 0.11 0.066 0.37 0.051 0.028 0.147
2300 4250 1730 5300 4050 2760 6080 4400 2910 3600 4070 2130 7200 2950
661 2274 244.3 1044 778 719 1016 1199 412.3 398 714 449.8 2622 808.5
44.5 273 45 50.1 44.68 62.7 70 58.3 71.1 57.3 130 79.6 51.68 158.5
Adasiya area This area lies south of the Yarmouk River along its course in the Jordan Valley area. The rocks building in the area consist of recent sediments deposited from the Yarmouk River and other smaller wadis and from the recent ancestors of the Dead Sea such as the Lisan Lake. They consist of weakly cemented gravel, sand, marl, and some silt and clay. The gravel matrix consists of basalt, limestone, and chert fragments. The groundwater in these recent wadi fill deposits originates partly from flood flows of the wadis, mainly from the Yarmouk River, and partly from groundwater lateral flows and upward movements into the wadi deposits. The latter groundwater is found in the silicified and phosphatic (B2/A7) aquifers confined upwards by the oil shale (B3) composed of bituminous marl (El-Nasser 1991). The EC values of 1060 to 2050 μS/cm (Table 20) reflect a mixture of flood flow water with EC values of 100 to 250 μS/cm, lateral flow groundwater with EC values of 680 to 1100, and Jordan Valley brackish to saline water with EC values of 4600–49,000 to 5000 μS/cm (Tables 11 and 12). The Br− concentrations in Adasiya groundwater range from 1.6 to 6.5 mg/l, but most wells have concentrations of 2.5 to 4.5 mg/l. The F− and I− concentrations are moderate and range from 0.038 to 1.72 and from 0.0038 to 0.067 mg/l, respectively. The Cl/Br ratios are below 100, and mostly around 70. The moderate F− and the high Br− concentrations in addition to the low Cl/Br ratios indicate another origin of the water than the phosphate rocks. Because phosphate rocks contain
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Table 20 Electrical conductivity (μS/cm), halides concentrations (mg/l), and chlorine to bromine mass ratio (Cl/Br) in the high bromide waters in Adasiya area two to three samples from each site)
Sampling site
Br−
F−
I−
EC
Cl−
Cl/Br
N
E
Saada Sp. Jasura Sp. Abu Sido Sp. Shawahin Sp. Adasiya W. 6
1.6 2.38 3.48 2.40 6.47
0.44 0.56 0.038 1.72 0.035
0.067 0.026 0.042 0.004 0.059
1237 1222 2050 1060 2050
147 133 355.3 110.2 327.2
92 56 102 46 51
205 – 190.57 – 228
210 – 204.91 – 206
Khal. Wakid W.
4.6
0.210
0.018
1906
348
76
230.61
207.89
relatively higher F− concentrations, which normally become released into the groundwater during the long contact times with the aquifer rocks. It seems that the confining layer, the bituminous marl (B3) of the silicified and phosphate rocks (B2/A7), contribute Br− to the groundwater in the B2/A7 aquifer. In the Mukheiba wells, the Br− concentrations are moderate of about 1 mg/l although the producing aquifer is the B2/A7 and although it is also confined by the bituminous marl. But it seems that the water of Mukheiba wells originates only from the B2/A7 aquifer without any contributions of the deeper aquifers of the lower Cretaceous (Kurnub), Jurassic, and Triassic rocks containing evaporites. The deep wells in the area receive upward leakages from the deep aquifers and hence contain higher Br− concentrations. Lisan Formation covered areas The salinities of the Lisan water are very high 44,190–49, 000 μS/cm (springs). When diluted with other water sources, the salinity decreases according to the mixing ratios of Lisan water and other waters (Table 11). The Br− concentrations of the Lisan water is around 415 mg/l decreasing in the mixed water to 41 to 67 mg/l. 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 resemble sea water of about 300.
Discussion and conclusion After the beginning of uplifting of the highlands along the shoulders of the Jordan Rift Valley (JRV) as a result of taphrogenic tectonics in the Upper Eocene to Oligocene times, erosion of the Bituminous Marl (Muwaqqar Formation) of Danian to the Lower Eocene age and transport of weathering products into the newly formed depression along the JRV started taking place. The highlands of the Irbed area are still partly covered by the Bituminous Marl Formation, whereas this Formation has been totally eroded from the highlands of Ajlun, Salt, Suweilih, Amman, Karak, and Tafila which drain into the
Dead Sea area. Here, the underlying older Formations of Amman Silicified Limestone (Campanian age) and Massive Limestone (Santonian age) build the top of the highlands. Since the beginning of the uplift in Upper Eocene to Oligocene, rocks of hundreds of meters in thickness must have been eroded and removed along the shoulders of the JRV (Wiesemann 1969). But since the formations that are still covering the highlands are generally those directly underlying the Bituminous Marls, then the eroded rocks of hundreds of meters in thickness must have been composed of Bituminous Marls (200-240 m in thickness) and their overlying younger Chalk Marl Formations (about 500 m in thickness), eroded and transported to the Dead Sea area. The extent of the area along the eastern highlands, in which Bituminous Marls were eroded into the Dead Sea area, can be estimated at 6300 km2 (30–40 km E-W and 180 km N-S extension) excluding the rocks that were covering the Jordan-Dead Sea area proper, in which Bituminous Marls might still be found in the bottom of the Jordan Valley and Dead Sea areas as a result of down faulting and burial by more recent sediments. The volume of the eroded Bituminous Marls, considering a thickness of 200 m, is calculated to be 1260 km3. By an average bromide content of 18 mg in 1 kg of Bituminous Marl and a rock density of 2.3 g/cm3, a minimum total of around 45 million tons of bromide must have joined the Dead Sea water as a result of dissolution and transportation of the Bituminous Marl, only from the eastern highlands of the Dead Sea-Jordan Valley area. The bromide content of the Dead Sea water is around 5 g/ cm3 (Bender 1968, Neev and Emery 1967) and the volume of the Dead Sea water in the 1960s of the last century was around 130 km 3 (Neev and Emery 1967), hence its bromide content calculates to be 650 million tons. The sources of the other bromide must have been the erosion of the Bituminous Marls covering the areas of the western highlands of the Rift Valley and partly covering the Jordan-Dead Sea area; erosion of phosphate rocks, which before, used to cover extended areas on both sides of the Rift Valley; erosion and leaching of Jurassic and Triassic rocks; and other contributions to the feeding waters of the Dead Sea with flood water.
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After the regression of the Tethys in the late Miocene and the onset of uplifting along and down faulting of the Jordan Rift Valley (Burdon 1959; Bender 1968), surface and groundwater of the surrounding areas started moving towards and discharging into the newly created topographic depression along the Jordan Rift depression. These waters brought dissolved and suspended loads from the eroded rocks in the catchment areas of the depression. Which before the blocking of the drainage by Jabel Druz basalt eruptions had a catchment area of about 157,000 km2 compared to the present catchment of 43,000 km2 (Salameh and Al Farajat 2006; USGS 1998). The chemical loads included a variety of salts including bromide salts originating from the oil shale and phosphate rocks and Triassic and Jurassic evaporates. The different exitless lakes (ancestors of the Dead Sea) developing in the Jordan Rift topographic depression have been exposed to high evaporation rates, leaving the water in the lakes with continuously increasing salt contents throughout their history. At present, the Dead Sea has a total dissolved solid content of 320 g/l, and is even saturated with respect to halite. Br− has also concentrated in the lakes’ waters. The Cl/ Br mass ratio in the Dead Sea water is 42 compared to seawater with 300. Therefore, there must be a mechanism which caused that huge difference. Here, two explanations are possible: either NaCl has deposited at the bottom of the Dead Sea leaving Br− salts in dissolved form behind or that there is an additional high Br− concentration source contributing to the Dead Sea water. The results of this study show that most water sources feeding the Dead Sea contain high Br− concentrations. And it lies at hand to attribute the high Br− concentration in the Dead Sea water to these sources. This does in no way mean that the differential precipitation of chloride and bromide salts in the present Dead Sea and its ancestral lakes have not contributed to the very low Cl/Br mass ratio in the Dead Sea water. Volcanic rocks covering large areas in the northeastern part of Jordan and southern part of Syria, draining into the Dead Sea, are at present not contributing with elevated Br− concentration to the Dead Sea, as elaborated above in the Basalt Water section. But during, and probably immediately after, the eruptions of the volcanoes, in the Neogene to Pleistocene, they must have contributed significant amounts of bromide. The quantification of the different bromide shares contributing to the Dead Sea and its ancestral lakes by the oil shale, phosphate, volcanic rocks, and Triassic and Jurassic evaporites seems to be difficult at present, and requires more data and information. Since the start of shrinkage of the last ancestral lake of the Dead Sea with the beginning of the Holocene, major bromide contributions to the Dead Sea water must have originated from the deposits laid down in the ancestral lake of the Dead Sea,
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especially from Lake Lisan deposits which cover major parts of the Lower Jordan Valley and the northern parts of wadi Araba south of the Dead Sea. But, the bromide contents of the Lisan Marls must have originated from the older rocks units of Jurassic and Triassic evaporates, phosphates, and oil shale. The main contributor of water to the Dead Sea, during the pre-development era which started in the 1960s of the last century was the Jordan River with an average discharge of 1370 MCM/year and an average bromide concentration of 8 mg/l during the dry season and 4 mg/l during the wet season. This river drains not only major territories in Jordan but also all of the Dead Sea catchments in Syria and Lebanon and most of the Dead Sea catchment in Palestine and Israel. All other sources used to contribute and are still contributing with far lower amounts of water to the Dead Sea containing also far lower concentrations of bromide than the Jordan river. Acknowledgments The author would like to express his sincere thanks to all those who, directly or indirectly, helped in making this study possible: the University of Jordan, Prof. Dr. Fritz Frimmel, und Dr. Gudrun Abbt-Braun from Karlsruhe Institute of Technology (KIT), and Prof. Dr. Stefan Geyer, Halle University.
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