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چکیده
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Soil productivity index (SPI) is an important tool for evaluating land use and soil management practices for a variety of ecosystems. The aim of this project was to assess the SPI for 29 hectares of a solid waste management site located in northern Contra Costa County, California. The site is impacted with a variety of contaminants including total petroleum hydrocarbons (TPHs), polycyclic aromatic hydrocarbons (PAHs), and heavy metals, and is highly saline. Specifically, we compared the SPIs of the impacted sites with those of clean soils located nearby. For the purposes of analysis, we separated the contaminated areas into three components: high (HC), medium (MC), and low (LC) TPH concentrations in soil. One clean soil location (NC) was selected adjacent to the contaminated site for comparison. The SPI was assessed using 7 physical, chemical and biological soil properties (referred to as “indicators”) and analyzed as follows: 1) identification of the minimum data set (MDS) of the indicators, 2) interpretation of the indicators using principal component analysis (PCA), and 3) integration of all indicator scores into one SPI value. The data showed that soil salinity and sodicity (sodium adsorption ratio, SAR, and exchangeable sodium percentage, ESP), and soil organic carbon (SOC) concentration, were the most discriminating and key indicators for SPI assessment. The results imply that the long-term influence of depositing petroleum hydrocarbons and other contaminants into this solid waste management site had major negative impacts on soil structural stability and plant nutritional status.
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