Environmental Chemistry – Green Chemistry

Environmental Chemistry
Environmental Chemistry

What is Environmental Chemistry ?

Environmental chemistry deals with the study of the origin, movement, reactions, effects, and fates of chemical species in the environment, as well as the effect of human and biological activities on these,” according to the definition. “Scientific study of chemical and biological phenomena that occur in natural areas” is another definition.

Environmental Chemistry
Environmental Chemistry

This subject investigates impacts at many levels:

  • Local effects, such as the consequences of urban air pollution
  • Global consequences, such as ozone depletion

Overlapped Branches of Chemistry

Environmental chemistry is the study of chemical reactions that occur in the environment as a result of human activity. It includes many different fields such as physics, life sciences, agricultural sciences, medical sciences, public health, and sanitary engineering, as well as different branches of chemistry such as organic chemistry, analytical chemistry, physical chemistry, photochemistry, geochemistry, and biological chemistry. It also overlaps with different branches of chemistry such as organic chemistry, analytical chemistry, physical chemistry, photochemistry, geochemistry, and biological chemistry.

Scope of Subject

Environmental chemistry has a very broad reach. It covers research on how a clean environment function and what the natural chemical concentrations in the atmosphere are. It also investigates the impact of pollutants on the environment. It investigates environmental interactions through chemical processes, equations, solutions, units, sampling, and analytic approaches.

  • Chemical reactions in environmental components such as the atmosphere, hydrosphere, lithosphere, and biosphere are among the major themes covered in this area.
  • Chemical reactions in the environment during nutrient cycling, such as the Water Cycle or Hydrological Cycle, Carbon Cycle, Nitrogen Cycle, Oxygen Cycle, Sulphur Cycle, and Phosphorus Cycle.
  • Chemical interactions and changes in response to several types of pollution, including water pollution, air pollution, and soil contamination, among others.
  • Climate change, global warming, ozone depletion, acid rain, smog, eutrophication, and other chemical processes

Environmental Biochemistry and Toxicological Chemistry

The ultimate environmental concern is the preservation of life. Environmental Biochemistry is the branch of science that studies the effects of chemical species in the environment on living things. Toxicological Chemistry is a related field that studies the chemistry of poisonous compounds with a focus on their interactions with biological tissue and live beings. Toxicological chemistry is concerned with the chemical nature and reactivity of dangerous compounds, including their origins, applications, and chemical aspects of exposure, destiny, and disposal.

Chemical Indicators Basic to Environmental Interactions

Following indicators are of central importance in the study of environmental chemistry:

  • Dissolved oxygen (DO)
  • Chemical Oxygen Demand (COD)
  • Biochemical Oxygen Demand (BOD)
  • Total dissolved salts (TDS)
  • pH
  • Nutrients (nitrates etc.)
  • Heavy metals (e.g., Cu)
  • Pesticides

Major Areas of Concerns

Following areas is the concern of Environmental Chemistry:

Contamination of land by heavy metals

Heavy metals have significantly damaged the environment and its compartments. This has harmed the environment’s ability to support life and preserve its essential values. Heavy metals are recognized to be naturally occurring chemicals; however, they are introduced in considerable quantities in many environmental compartments due to anthropogenic activity. As a result, the environment’s potential to nurture life is harmed, putting human, animal, and plant health at risk. Because heavy metals are non-degradable, they accumulate in food chains, causing bioaccumulation. Heavy metal remediation necessitates extra caution to safeguard soil quality, air quality, water quality, human and animal health, and all sectors as a whole. Physical and chemical-heavy metal remediation systems that have been developed are prohibitively expensive, time-consuming, and emit more trash into the environment.

Leaching of nutrients from urban land

Increased population leads to land-use changes from natural to urban and agricultural land use. These perturbations not only reduce the natural treatment potential but also deteriorate the quality of surface water (SWQ). In general, anthropogenic land use, such as agriculture and urban areas, increases nutrient concentrations far more than natural lands, such as forests and wasteland. The inadequate nutrient conditions in SWQ might be improved by developing sustainable metropolitan regions rather than rural areas, creating high-standard wastewater treatment plants, and implementing efficient fertilizer applications. Natural water quality control strategies include riparian vegetation, grassed swales, and the creation of artificial wetlands as buffer zones. 

Urban runoffs

The surface runoff of rainwater caused by urbanization is known as urban runoff. This runoff is a major cause of flooding and pollution in urban areas all over the world. During land development, impervious surfaces (roads, parking lots, and walkways) are built. During rainstorms and other precipitation events, these surfaces (made of materials like asphalt and concrete) and rooftops transport polluted stormwater to storm drains rather than allowing it to seep through the soil. This results in a drop in the water table (because of reduced groundwater recharge) and flooding (due to the increased volume of water remaining on the surface). Stormwater is discharged untreated into streams, rivers, and bays by most municipal storm sewage systems. Basement backups and seepage through building walls and flooring can also allow excess water to seep into people’s homes.

Key Methods Applied in Environmental Chemistry

Quantitative Chemical Analysis is the key method used in environmental chemistry. It includes the use of common analytic techniques, e.g., Gravimetric and Electrochemical methods, Spectroscopy, Mass spectrometry, Study of radiochemical and alpha, beta, and gamma radiation.

Key Terms of Environmental Chemistry

Major terms of environmental chemistry are:


A pollutant occurs when the concentration of a material already existing in nature is elevated to an unrequired ratio as a result of human activity and this harms the environment, either by lowering the quality of life or damaging health. Sulfur dioxide, carbon monoxide, lead, mercury, excess heat, sound, and other contaminants are examples.


Contamination is a material that does not occur naturally but is introduced into the environment as a result of human activities. When a contaminant harms human health, it is referred to as a pollutant. It is a pollutant as well.


A pollutant’s receptor could be anything that is impacted by it. Man, for example, is a receptor of contaminated water because it causes cholera and gastroenteritis.


It is the medium that interacts with the long-lived pollutant and holds it in place. The seas act as carbon dioxide sinks in the atmosphere. Pesticides used in agriculture sink into groundwater and subsoil water.

Dissolved Oxygen (DO)

Aquatic life requires oxygen dissolved in water. In good quality water, the dissolved oxygen level should be between 4 and 8 mg/l. It is consumed as a result of the oxidation of organic matter, reducing agents, and other substances found in water. Water that has a DO value of less than 4 mg/L is termed polluted and is unfit for human or aquatic animal consumptions.

Chemical Oxygen Demand (COD)

It is a measure of the organic content of water, as organic matter with a biological origin, such as dead plants, is the most prevalent component oxidized by dissolved oxygen in the water. The chemical oxidation of organic materials by K2Cr207 in 50 percent H2SO4 determines the COD of a water sample. Other reducible inorganic species that may be present in water, such as NO2-, S203-2, S-2, and others, are included in this approach, so it does not accurately reflect the organic composition of water. This method, however, is extensively employed because of its speed.

Biological Oxygen Demand (BOD)

BOD refers to the ability of organic matter in a sample of natural water to consume oxygen. It is assessed empirically by measuring dissolved oxygen (DO) in a sealed sample at the beginning and conclusion of a 5-day period. The BOD is the amount of oxygen used or consumed within a given time period as a result of the oxidation of dissolved organic matter in a water sample.

Threshold Limit Value (TLV)

This figure represents the maximum amount of a harmful pollutant in the atmosphere to which a healthy industrial worker can be exposed for an eight-hour day without experiencing any negative consequences. Animal experiments, medical knowledge and experience, and environmental studies are all used to determine a pollutant’s TLV.


Key Concept – Environmental Contamination

Contamination is a material discovered in nature at higher-than-normal concentrations or that would not otherwise be there. They are caused by human action. Contaminant and pollutant are two terms that are used interchangeably. Contaminants, on the other hand, may or may not harm the environment, whereas pollutants invariably do. The following are two key principles in environmental chemistry:

Receptors are organisms that are impacted by toxins or poisons.

Sink refers to a chemical medium or species that retains or interacts with pollutants or contaminants.

New Orientation – Green Chemistry

Green chemistry, also known as sustainable chemistry, is a branch of chemistry and chemical engineering that focuses on developing products and processes that consume and generate less hazardous substances. Green chemistry focuses on technological techniques to preventing pollution and lowering non-renewable resource usage, whereas environmental chemistry focuses on the impacts of harmful chemicals on ecosystems.

 Green chemistry is based on the following principles:

  • Pollution Prevention
  • Atom Economy
  • Less Hazardous Chemical Synthesis
  • Designing Safer Chemicals
  • Safer Solvents and Auxiliaries
  • Design for Energy Efficiency
  • Use of Renewable Feed-stocks
  • Reduce Derivatives
  • Catalysis
  • Design for Degradation
  • Real-time analysis for Pollution Prevention
  • Inherently Safer Chemistry for Accident Prevention

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