NATURAL RADIONUCLIDES AND TRACE ELEMENTS IN

Document Sample
NATURAL RADIONUCLIDES AND TRACE ELEMENTS IN Powered By Docstoc
					    NATURAL RADIONUCLIDES AND
   TRACE ELEMENTS IN GEOTHERMAL
    SPRING, AL-LITH REGION, SUADI
                ARABIA

          Khater A. E. M. 1&2, Hussein M.T.1
 1College of Science, King Saud University, Riyadh,

Kingdom of Saudi Arabia, 2Atomic Energy Authority,
                     Cairo, Egypt
   http://faculty.ksu.edu.sa/Khater/default.aspx
Earth's internal heat comes from a combination of
residual heat from planetary accretion (about 20%) and
heat produced through radioactive decay (80%).

The major heat-producing isotopes in the Earth are
potassium-40, uranium-238, uranium-235, and
thorium-232.
Earth cutaway from core to exosphere
                                                                     In



The water issuing from a hot spring is heated by geothermal heat,
i.e., heat from the Earth's mantle. In general, the temperature of
rocks within the earth increases with depth.. If water percolates
deeply enough into the crust, it will be heated as it comes into
contact with hot rocks. The water from hot springs in non-
volcanic areas is heated in this manner
In active volcanic zones, water may be heated by coming into
contact with magma (molten rock). The high temperature
gradient near magma may cause water to be heated enough that
it boils or becomes superheated.

If the water becomes so hot that it builds steam pressure and
erupts in a jet above the surface of the Earth, it is called a geyser.

If the water only reaches the surface in the form of steam, it is
called a fumarole.

If the water is mixed with mud and clay, it is called a mud pot.
Thermal and mineral water springs are considered to be
important natural sources.

Chemical studies of thermal waters provide information regarding
the type of geothermal reservoir (liquid or vapor dominated),
reservoir base temperature, subsurface flow patterns and
chemical quality.
Areas of outcropping Precambrian rocks in the Arabian plate and adjacent
                        areas of the African plate
In Saudi Arabia , two major locations of fracture controlled
springs.

The two locations are in the Al lith and Jizan areas. In Al lith

area four fracture springs, the four springs seem to be aligned

on major fracture trend having a NW-SE orientation. The

fracture cut through granitic, dioritic, and bio-titegneissic rocks.
Hot springs in Al- Lith Area
Location map and general geology of Al-Lith area
               Experimental work
• Sampling: Water samples were collected in 5 L capacity
polyethylene containers, and transferred and kept in darkness
for preservation,
•U, TH, K concentrations, µg.L-1, were measured using
PerkinElmer model ELAN-9000 ICP-MS at ALS lab., Vancouver-
Canada
•Ra isotopes (Ra-228 and Ra-226) were measured using LSC and
alpha spectrometer after chemical separation,
•Po-210 was measured using alpha spectrometer after chemical
separation
 Water physical and chemical properties such as pH, EC (electric
conductivity, dS.cm-1), major cations (Ca, Mg and K) and major anions
(CO3, HCO3, Cl and SO4) were determine using standard methods (Al-
Omran 1987)
            Results and Discussion
Discharge    TDS,     EC             T   Name of 
   rate       ppm    µS /cm   pH    °C   springs

  3 L/s      1810    3050     7.2   45    Bini-Hilal

 2.1 L/s     1785    2970     7.1   60   Al-Harrah

 0.25 L/s    3066    5270     7.7   45    Markub

    _        3925    6790     7.3   35    Daraka
 Spring      pH       Field         Total     Conductivity   Turbidity     Total
 Name              Temperature,   Dissolved    as µs/cm       (NTU)      Alkalinity
                        ˚C         Solids                                (as CaCO3)
Bani Hilal   7.2       45           1810         3050          0.48         138
AlHarra      7.1       60           1785         2970          0.32         100
MarkuB       7.7       54           3066         5270          0.84         148
 Daraka      7.3       35           3925         6790          0.91         161
Spring       Total      HCO3      Total       Ca     Mg     Na    K     Cl    SO4   NO3
Name       Alkalinity          Hardness (as
          (as CaCO3)             CaCO3)
 Bani        138        168        717        260   16.2    350   21   672    399   1.6
 Hilal
AlHarra      100        122        690        252   14.58   352   21   671    402   1.55

MarkuB       148        180       1218        433   32.8    625   24   1492   330   7.5

Daraka       161        196       1604        549   56.2    800   25   1934   470   8.8
•All spring are located in the vicinity of granite boundry along a
cataclastic zone.
•Three springs, Al-Harra, Markub and Darakah, represent
different fractions of a mixture of thermal water with confined
aquifer. Al-Harra, the least mixed spring contains 48 % of surface
water (Al-Dayel, 1988).

•The estimated temperature of the deep fluids is 120 oC using
silica geothermometer and 100 oC using the Na-K geo-
thermometer. The Na-Li and Na-K-Ca geothermometer also
confirm these temperature.
Using stable isotopes (H-2, H-3 and O-16), suggest …. A
mixture of hot deep water and recent seepage water
(Bazuhair et al., 1990)



The enrichment of Cl and SO4 in groundwater is generally
either due to mixing of seawater or to dissolution of
evaporite minerals present in sediment deposited under
a marine environment.
                               SO4/ Ca/          Mg/     (Cl+SO4)/ (Na+K)/    Cl/
             Na/Cl Ca/Cl Mg/Cl Cl   Mg           Ca      HCO3      (Ca+Mg)    SO4
 Bani
 Hilal        0.52   0.39   0.02   0.59   16.0    0.06        2.9       1.3     1.7
AlHarra
              0.52   0.38   0.02   0.60   17.3    0.06        2.9       1.4     1.7
MarkuB
              0.42   0.29   0.02   0.22   13.2    0.08        2.8       1.4     4.5
    Daraka
              0.41   0.28   0.03   0.24    9.8    0.10        2.9       1.4     4.1




Depletion in Ca+Mg and enrichment of Na+K in thermal
water may be due to an interaction of CO2 with water and
rocks. In fact, CO2-rich water facilitates Ca-Na exchange
processes in feldspars and clay minerals.
 ppb           1          2          3           4    MCL
  As    10          10         20          20         10
  Cd    0.1         0.6        0.5        0.55        3-5
  Mn   <0.01       0.05       0.16       <0.01       0.4-50
  Pb   <0.2                                          10-15
  Hg   <0.2                                           1-6
  Th   <0.01                                 
  Co   <0.02                                 
  Cr   <0.02                                         50-100
  Zn   <0.01                                         3000
                 1       2      3      4
   U, ug/L      0.025   0.03   0.02   <0.01
U-238, mBq/L    0.31    0.37   0.25     -
   K, mg/L       18     20     25      26
 K-40, Bq/L     0.56    0.63   0.77   0.81
   Ra-226       <DL     <DL    <DL    <DL
   Ra-228       <DL     <DL    <DL    <DL
Pb-210, mBq/L    17      6      7      - 
     E           6.8    1.62   1.89    - 
Activity concentrations (Bq/L) of Ra-226, Ra-228, U-238, Pb-210 and K-
40 in thermal and mineral waters in different countries
Country Ra-226         Ra-228       U-238           Pb-210               K-40

Jordan 3.8–6.8         1.67–2.37    2.10–5.95       —                     23–35
Spaina <0.06–1.1       —            <0.03–0.50      —                      —
Croatia 0.07–4.40      —            —               —                     —
Brazila <0.01–0.22     <0.01–0.75   —               <0.01–0.51            —
Brazila —          —   —            <0.004–0.78     —7
Tunisia 0.034–3.9      —            0.002–0.043     —                    <2.4–3.9
Egypt    <0.28–3.6     <0.16        0.035–0.09      0.003–0.026          <1.0–14
Saudi Arbia<0.05       <0.05        0.0003-0.0004   0.006-0.017         0.56-0.81
aMineral waters 
In conclusion, the uranium activity concentrations of the whole

set of waters investigated are low. In Finland, for example,

some waters have shown activities above 1.5 Bq/L in uranium,

which is due to high uranium concentration in the subterranean

rocks.
In springs, both radium and uranium distribution are affected

by temperature, salinity and redox conditions. Uranium

depletion is probably caused by reduction of U6+ to insoluble

U4+ during water circulation through the vent system. The total

removal of uranium in association with high temperature

hydrothermal circulation has been estimated in other studies.
                    CONCLUSIONS

qThermal spring in Al-lith region are a part of the thermal field

at the edge of the Red Sea tectonic plate boundry.

qThe acticity concentration of natural radionuclildes and

concentration of some trace element are low comparing to other

hot springs

qThe impacts of hot spring on the environmental quality of soil

and groundwater should be studied.
Thank you
Serious negotiations to declear their rights
     for a clean and save environment
……more food in the desert will be nice too
                   !!!!!!!

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:10
posted:7/24/2013
language:
pages:31