Wednesday, November 7, 2007
302-6
Dynamic Soil Properties Across a Suburban Landscape, Ankeny, Iowa.
Humans influence soil properties through urbanization. This study investigated the degree to which humans influence dynamic soil properties (bulk density, organic carbon, and heavy metal concentrations) in a suburban landscape and assesses the variability of these soil properties with respect to the length of time that has passed since disturbance or construction activities. Aerial photos were used to delineate residential areas from different years and nine time periods of development were established. Ten homes from each time period of development were randomly selected and soil samples were collected from the center of the front yard of each home. A composite of five cores were divided into 0-5, 5-10, and 10-20 cm increments. The soils were analyzed for bulk density, total carbon, inorganic carbon, organic carbon, heavy metal concentrations (Cd, Co, Cr, Cu, Ni, Pb, Zn), pH, and particle size distribution. It was found that bulk density ranged from 0.68 to 1.88 g/cm3 for the entire study area. The mean soil bulk density for the time periods ranged from a low of 1.23 g/cm3 for soil adjacent to homes built prior to 1939 to 1.70 g/cm3 for soil adjacent to homes built from 2003-2005. The bulk density was positively correlated with the sand content, the latter of which contributed to the higher bulk density in soils from the most recent time periods of development. The organic carbon ranged from 0.01 to 8.41 % for the entire study area. The mean organic carbon for the time periods of development ranged from 4.49 % from soils around houses developed prior to 1939 to 0.49 % for soils from time period of development 2003-2005. Concentrations of Cu and Pb were higher in soils from older residential areas. Nickel concentrations increased with depth. All the heavy metals were positively correlated with one another except Zn.
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