8 Environmental Organic Chemistry#
Introduction#
Organic chemicals are intimately tied to all aspects of modern societies from consumer goods to pharmaceutical chemicals to household products. More than 9 million carbon-based natural and anthropogenic compounds have been identified. It is no surprise, then, that organic contaminants are ubiquitous in our environments. What happens to an organic compound when it is introduced into the natural environment? The answer depends on the physical and chemical properties of the compound.
In this chapter, we will familiarize with some basic principles of organic chemistry and how organic chemicals behave in the environment.
Fossil Fuels#
Fossil fuels are made up of hydrocarbons, which are compounds of hydrogen and carbon atoms. The carbon found in fossil fuels is primarily in the form of hydrocarbons such as methane, ethane, propane, butane, and octane. These hydrocarbons are formed from the remains of dead plants and animals that have been buried and subjected to heat and pressure over millions of years.
Natural gas is primarily composed of methane (\(\ce{CH4}\)), a simple hydrocarbon, but can also contain other hydrocarbons such as ethane (\(\ce{C2H6}\)), propane (\(\ce{C3H8}\)), and butane (\(\ce{C4H10}\)).
Coal is primarily composed of carbon, but it also contains small amounts of other elements such as hydrogen, sulfur, oxygen, and nitrogen. Coal is formed from the remains of plants that lived millions of years ago. The carbon in coal is derived from the carbon that was present in these plants. The nature of this carbon can vary depending on factors such as the type of plant, the environment in which it grew, and how long ago it lived.
The exploitation of fossil fuels have left an indelible impact on many of Earth’s environments.
Natural Organic Matter#
Carbon is the main element present in natural organic matter (NOM) and is complex and not fully understood. The NOM contains complex molecules of carbon bonded with other elements, such as hydrogen, oxygen, and nitrogen.
Organic matter is a major component of soil, and it plays an important role in soil fertility. It helps to hold water and nutrients in the soil, and it also provides a habitat for soil organisms. Organic matter is also a major component of living things, and it is essential for life. It is used to build cell structures, and it is also involved in many metabolic processes. Carbon in soil organic matter is also a very important reservoir of carbon in the global carbon cycle.
The carbon in organic matter is not stable, and it can be decomposed (by oxidation) to \(\ce{CO2}\) with the help of microorganisms. Decomposition is important because it releases nutrients back into the soil, which can be used by plants.
The carbon in organic matter is a valuable resource, and it is important to understand its nature and how it is cycled through the environment. This knowledge can help us to manage our resources wisely and to protect the environment.
Organic Pollutants in the Environment#
Anthropogenic organic pollutants are chemicals can come from a variety of sources, including industrial emissions, agricultural runoff, and consumer products. The pollutants can have a variety of effects on the environment, including polluting water and soil, harming wildlife, and disrupting human health.
Organic pollutants are commonly released into the environment through industrial emissions (volatile organic chemicals, untreated waste discharges, etc.), agricultural runoff (herbicides, pesticides, etc.), consumer products (nonstick cookware, household cleaners, personal care products, etc.), and human and animal waste (caffeine, medicines, etc.)
Once these pollutants are in the environment, they can have a variety of effects in water and soil. For example, some pollutants can cause fish to die or make them more susceptible to disease. Some pollutant exposure can also cause health problems including cancer.
It is important to understand the chemical nature, sources, and effects of organic pollutants so that we can take steps to protect the environment and human health.
Learning Goals#
Learning Goals
The main goals for this chapter are to:
learn the basics of organic chemical nomenclature,
explain how organic chemicals behave in various geological environments, and
apply basic thermodynamic principles to determine partitioning of organic chemicals in geological environments.