The relation between climatic parameters (relative air humidity) and the water activity of the Urmia Sea water determines the possible maximum evaporation of the lake. Using the Pitzer thermodynamic approach, the activity of the Urmia Lake water during evaporation was calculated and compared to the present relative air humidity above the water. Present climatic conditions allow the Urmia Sea water to evaporate down to water with activity of 0.55, corresponding to the lowest air humidity measured over the lake. This water activity falls in the range of halite precipitation, while carnalite precipitation starts at somewhat lower (a H2O = 0.499) point. Our dynamic model predicts that for air humidity as low as 55% (reflecting present climate conditions), the Urmia Sea level may drop to as low as 1270 m (i. e., 1270 m above mean sea level). At that point, the lake water volume will have a volume of 11 km3. For the sake of comparison, at the beginning of 1990, the level of the lake was 1275 m, its volume was 25 km3, and its surface area was 5145 km2.
展开▼
机译：气候参数（相对空气湿度）与Urmia海水的水分活度之间的关系决定了湖泊可能的最大蒸发量。使用Pitzer热力学方法，计算了Urmia Lake水在蒸发过程中的活度，并将其与水上方当前的相对空气湿度进行了比较。当前的气候条件使Urmia海水蒸发至活动度为0.55的水，这对应于整个湖泊测得的最低空气湿度。这种水活度处于盐岩沉淀的范围内，而钠钙榴石的沉淀则开始于较低的点（H2O = 0.499）。我们的动力学模型预测，对于低至55％的空气湿度（反映当前的气候条件），乌尔米亚海平面可能会降至1270 m（即，比平均海平面高1270 m）。届时，湖泊水量将达到11 km 3 。为了便于比较，在1990年初，该湖的高度为1275 m，其体积为25 km 3 ，其表面积为5145 km 2 。
展开▼
