SOIL MOISTURE, TEXTURE AND ORGANIC MATTER EFFECT ON POTENTIAL PARTICULATE MATTER EMISSION (PM10) FROM ARGENTINIAN SOILS

MARIANO J. MENDEZ, SILVIA B. AIMAR, ROGER FUNK, DANIEL E. BUSCHIAZZO

Santa Rosa, La pampa

Congreso; ICARVII (International Conference on Aeolian Research); 2010

International Society for Aeolian Research - ISAR

The emission of fine particulate matter (particles smaller than 10 µm in diameter, PM10) from soils into the air is related with negative effects on human health and influences on atmospheric processes. PM10 emissions from soils are closely related to texture, but soils from the same textural class can release significantly different amounts. Soil moisture is an important factor controlling dust emission, which, again, depends on soil texture. Aim of this study was to evaluate texture, organic matter (OM) and soil moisture effects on PM10 emissions of several soils from arid and semiarid areas of Argentina. Measurements were carried out in a wind tunnel, on 7 soils of different regions of Argentina which were treated to obtain water contents ranging from zero to the specific threshold of each soil after that no further PM10 emission occurred. Results showed that the maximum PM10 emissions were always measured on oven-dried samples (105°C, 60°C), ranging from 1337 to 6500 µg g-1, while linearly decreases occurred with increasing water contents. A 85% of the slope value (b factor of the regressions between PM10 emissions and soil moisture content for each soil) was explained by the quotient OM/silt in a potential and positive way. This was explained on the basis of the better aggregation produced by increasing OM contents and the filling of soil pores inside the aggregates, which bonds the fine and coarse particles with higher energy in coarse soils. Maximum PM10 emissions were related to the quotient silt/1+OM, indicating increasing emissions with increasing silt- and decreasing OM contents. Such tendency was again explained on the basis of the aggregation produced by OM contents. PM10 emissions of air dried soils and wet soil was predicted using the soil moisture and clay content (p<0.01, R2=0.86). The silt and OM effects on PM10 emissions of air dry and wet soils is expressed through the soil moisture whose effects on PM10 emission depend of OM/silt ratio. This study showed that PM10 emission differs largely among soils of coarse texture and that the soil silt and OM content are main factor that explain those variations. The soil silt and OM content also explained the changes in the moisture effect on PM10 emission of sandy soil. Variations in PM10 emission and moisture effect among soils of other textural classes should be studied.