Selenium Levels in Lebanese Soils, Plants and Water.

Selenium was measured in 60 soil samples, 86 plant samples and 13 water samples by ICP-MS. The samples were collected from major agricultural regions in Lebanon. The results of soil analysis indicate that soluble Se < KH₂PO₄–Se < HNO₃–Se. The ratio of soluble Se: KH₂PO₄–Se : HNO₃–Se were about 1:3:13. The Se levels in soil samples ranged between medium to high. Se levels in edible portions of plants followed the following order: radish > lettuce > cucumber > cabbage > parsley > onion leaves > broccoli > tomato > mint > chickpeas > wheat > onion bulbs. The Se level in water samples collected from springs ranged between 2.7-17.6 µg/L (average 7.4 µg/L) and between 2.1-5.1 µg/L in bottled water. The lower level of  Se in bottled water was expected because bottled water is filled from excellent quality water at elevation of 1600 m minimum. The EPA safe value for drinking water is less than 50 µg/L. The results indicate that plant type, variety, and growth stage are factors that affect Se levels in plants. Se levels in plant tissue was affected by soil pH, CaCO₃ and organic matter contents. In the calcareous soils of Lebanon, the three Se fractions (soluble–Se, KH₂PO₄–Se, and HNO₃–Se) are good indicators of available Se in soils.