Abstract
Soil, the final product of long-lasting forming processes, is a nearly non-renewable source and an environmental necessity. Soil contamination, also known as soil pollution, which is generally defined as the presence of man-made chemicals and alterations in soil, is widely capable of causing long-term health issues and a disrupted ecosystem. From a general scientific point of view, soil contaminants can be classified as Macro and Micro contaminants by quantity, while micro-contaminants divide into two groups: organic and inorganic pollutants. Contamination types can be also categorized by contamination source. Subsequent to verifying the type of contaminant and in order to amend contaminated soils, varieties of methods are provided. Physical, Chemical, and Biological (Bio-Remediation) techniques are used to extract, degrade, or immobilize soil contaminants. These methods can be utilized as a single technique or as a combination of methods. The objective of this chapter is to clarify the soil contamination and the approaches to amendment.
TopBackground
As an ongoing concern, soil contamination due to industrialization has always been a dominant problem. Studies on soil pollution by industries have been carried on to verify the most common contamination sources. According to Kabir, Ray, Kim, Jeon, and Kim, et al. (2012) the most common hazardous industrial contaminants are metals, such as lead, zinc, cadmium, and copper. Considering the mean concentrations, these contaminants can be classified into three groups; Pb, Zn, Ni, Cu, Fe, and As in smelting and metal production industries, Mn and Cd in the textile industry, and Cr in the leather industry. In many instances, contaminant levels in the studied site have been found to outreach the common regulation of many countries guideline levels. As an anthropogenic raw material, crude oil has been used in production of plastics, paint and solvents. Oil demand, globally produced in striking amounts, has been predicted to obtain a daily demand of 92.9 mega-barrels in 2015, with an elevating need approaching 110 mega-barrels in 2035. According to estimation by the European Environment Agency in 2006, crude oil was the most dominant pollutant of the inquired contaminated sites, at 33.7%, which had the second place after heavy metal pollution (Valentín, Nousiainen, & Mikkonen, 2013). The carcinogenicity of specific PAHs has been established in laboratory studies. Researches show that PAHs also can influence the hematopoietic and immune systems and are capable of creating reproductive, neurologic, and developmental defaults (Straif, Baan, Grosse, Secretan, Ghissassi, & Cogliano, 2005).
According to a study in Beijing, China, heavy metal concentration in plants from soils irrigated by waste water has significantly excelled the control level of State Environmental Protection Administration (SEPA) in China and the World Health Organization (WHO) (Khan, Cao, Zheng, Huang, & Zhu, 2008). Analysis in Niger Delta Area (NDA) has proved that the heavy metal concentration levels have exceeded some guideline and standard values (Olawoyin, Oyewole, & Grayson, 2012). An investigation of forest sites of Austria has revealed that the north Austria has been observed to be comparably higher polluted by PCDD/F, PCB, HCH, HCB, PCP, DDX and PAH (Weiss, Lorbeer, & Scharf, 2000). An investigation of Pb levels in farmland soils in Henan Province, surrounding a Pb smeltery, has shown that the Pb concentrations in children blood, living in the vicinity of the sites, exceeded the international Pb poisoning diagnostic criteria (Zhou, Lei, Yang, Zhou, Guo, Chen, 2013) .
Key Terms in this Chapter
Macronutrients: Soil minerals that are consumed in larger quantities by plants.
Soil Aggregates: Alignment of soil particles, which often create different shapes in soil.
Humification: Soil organic matter decomposition, and humus formation.
Redox-Potential: Oxidation / reduction potential, is a measure of the chemical species liability to acquire electrons and to be reduced.
Humic Acids: Fraction of soil organic matter, which are soluble in water more than pH 2, their molecular size range from approximately 10,000 to 100,000.
Carcinogen: any substance that directly causes cancer
Fulic Acids: Fraction of soil organic matter, which are soluble in water under all pH conditions, their molecular weight range from approximately 1,000 to 10,000.