Dust Particles and Aerosols: Impact on Biota A Review (Part I)

The impacts of Dust and Sand Storms (DSS) on people, crops, livestock, infrastructure and health are well documented. Data have accumulated on the deleterious effects of dust aerosols when they settle on plants. Sand blasting of low growing plants is a common cause of failure in reforestation efforts. Burial of plants by moving sands are also a cause of much damage. The physics of moving sand and dust particles is outlined and the mechanics of each type of damage is elaborated. The physical effects of dust accumulating on leaf surfaces, leaf physiology such as photosynthesis, transpiration, stomatal conductance and leaf temperature of many different species of plants were investigated. It was found that dust decreases stomatal conductance in the light, and increased it in the dark by plugging the stomata, when the stomata were open during dusting. When dust of smaller particles was applied, the effect was greater. However, the effect was negligible when the stomata were closed during dusting. The dust decreased the photosynthetic rate by shading the leaf surface. The paper also reviews experimental work on the physiological effects of dust on photosynthesis, stomatal function, respiration and transpiration. Examples are drawn from western Iran where oak woodlands (Quercus brantii) are under threat from dust that blows in from Iraq and Syria.