Estimation of Baseline Concentration of Some Trace Elements and the Effect of Farming Practices on the Distribution of Accumulation and Pollution Loading Indices in the Soil of Boroujen-Faradonbeh Plain

Soil pollution, i.e. elevated concentration of undesirable organic and inorganic matter such as trace elements higher than natural background concentration can be a consequence of indirect or intentional human activities. Evaluation of the effect of the agricultural operations and particularly using the wastewater on soil trace element concentrations is useful and required to manage the land and reduce the health risks of the food products. The aims of this study were: [1] The estimation of the mean concentration and max limit of the background concentration for Cd, Cr, Ni, Pb, Co and Hg in the surface soil samples of Boroujen-Faradonbeh plain; and [2] Evaluation of the effect of agricultural operation and farming by non-conventional water on background concentration and on accumulation, distribution and pollution load of the soil of this plain.
Boroujen-Faradonbeh is an agricultural plain loaced in the Chaharmahal and Bakhtiari mountainous province of Iran. Two hundered surface soil samples (0-20 cm) were taken from three types of land: never-uncultivated soil (20 samples), freshwater-irrigated (90 samples) and wastewater-irrigated (90 samples) soils. The total sampled area was about 2340 hectares. The exact position of the samples were recoded using a GPS device. The total concentrations of Pb, Co, Ni, Cd, Cr and Hg in the samples, and the background and upper limit concentrations were determined. In addition, pollution loading index (PLI) for the whole plain determined and delineated. To separate the affects of agricultural practices and wastewater application the analysis of variance of StatSoft Statistica 12 was used. Maping, and related operations were conducted inside ArcGIS 9.3.
Background concentrations of Ni, Cd, Cr, Hg, Co, and Pb, were determined as 1.13, 0.16, 1.56, 0.09, 0.80, and 1.52 mg/kg, respectively; while upper limit concentrations for the mentioned trace elements were respectively 1.3, 0.28, 1.6, 0.16, 0.9, 1.7 mg/kg. Conventional farming (application of fertilizer but not wastewater) increased the soil accumulation factor of Cd and Pb to 1.7 and 1.9 (p