Migration and Transformation of Chemical Pollutants as Mixtures

As civilization has evolved, industrial and human daily activities, such as the production of chemicals and agents and the incineration of municipal solid waste, have contributed significantly to environmental pollution. The quality of subsurface water sources is at risk, the soil is deteriorating, structural properties are changed, the atmosphere is polluted, and even aquatic and terrestrial creatures are harmed. In this chapter, the focus of pollutants is on volatile organic compounds (VOCs), some persistent organic pollutants (POPs). VOCs with high vapor pressure mainly exist in the atmosphere and are prone to migration. VOCs are potent ozone (O 3 ) precursors that provide the OH radicals needed in ambient air for the generation of ground-level O 3 , making them photochemically reactive organic molecules in atmospheric chemistry. On the contrary, POPs are a type of organic pollutant with low vapor pressure, although they can still rely on the atmosphere for long-distance migration. In addition, POPs are difficult to environmentally degrade and very toxic, which can be enriched in the food web and bring health risks to human beings. Both VOCs and POPs always occur in the form of a mixture in the environment. Different types or numbers of substituents connected to the same molecular skeleton result in multiple congeners. Therefore, paying attention to the overall geochemical behavior of mixed pollutants is more conducive to understanding the characteristics of pollutant migration and transformation.