Fig 1.
The map on the right shows the location of the three reservoirs (King Talal Dam, Al-Wihdeh Dam and Wadi Al-Arab Dam) within the lower Jordan watershed between Lake Tiberias and the Dead Sea.
The morphological characteristics of the reservoirs are shown in the detailed maps on the left at different scales.
Table 1.
The main physical characteristics of the three reservoirs.
Numbers are provided as mean±SD (standard deviation), if available.
Fig 2.
Time series of the physico-chemical parameters in three reservoirs King Talal Dam (black), Wadi Al-Arab (green) and Al-Wihdeh (blue): (a) Daily mean surface area, (b) daily mean water volume, (c) water surface temperature, (d) alkalinity, and (e) pH.
Table 2.
Summary of the measured and estimated physico-chemical variables and CO2 fluxes for the three reservoirs.
n indicates the number of available water chemistry samples. All numbers are given as mean±SD. The arrows in parentheses indicate significant linear temporal trends (↑ increasing, ↓ decreasing,—not significant for p<0.05).
Table 3.
Cross-correlation coefficients for the selected parameters: pH, alkalinity (Alk) in mmol l-1, salinity (S) in ppt, temperature (T) in °C, pCO2 in μatm, CO2 flux (Flux) in mg CO2 m-2 d-1, water volume (V) in m3, gas exchange velocity (k’600) in m d-1 and chemical enhancement factor (α).
For each combination of parameters, the three numbers are the cross-correlation coefficients observed for King Talal (upper), Wadi Al-Arab (middle) and Al-Wihdeh (lowest) dams. The most significant correlation coefficients (p<0.05) are marked bold, while p<0.1 for the remaining correlations. Not significant correlations are marked as x.
Fig 3.
Time series of the monthly estimates of pCO2 for (a) King Talal Dam (black), (b) Wadi Al-Arab Dam (green), and (c) Al-Wihdeh Dam (blue).
The dashed lines show the mean atmospheric pCO2 (396 μatm).
Fig 4.
The frequency distribution of (a) gas exchange velocity and (b) chemical enhancement factor for the three reservoirs.
Fig 5.
Time series of the CO2 flux for the three reservoirs in (a) King Talal Dam (black), (b) Wadi Al-Arab Dam (green), and (c) Al-Wihdeh Dam (blue).
The y-axes is in different scale and the dashed lines were fixed at zero.
Fig 6.
Atmospheric fluxes of CO2 as a function of pH in the three reservoirs.
R2 denote to the linear regression.
Fig 7.
Chemical enhancement factor as a function of unenhanced gas exchange velocity k’CO2 for three different pH values (color) and at two different temperatures (solid line: 25°C, dashed line: 7°C).
The dotted line indicates a reciprocal relationship between both parameters and therewith a resulting exchange coefficient, which is independent of wind speed. Chemical enhancement further depends on salinity, which was fixed at a value of 0.8 ppt.
Table 4.
Comparison of the estimated mean flux of CO2 with zonal and global estimates from the recent literature.