Deutsch: Chrom / Español: cromo / Português: cromo / Français: chrome / Italiano: cromo

Chromium is a chemical element with the symbol Cr and atomic number 24. It is a hard, lustrous metal known for its high corrosion resistance and hardness. In the environmental context, chromium becomes significant due to its various states and impacts on ecosystems and human health.

Chromium sources of emissions include the Combustion of coal and oil, electroplating, vehicles, iron and steel plants, and metal smelters.

The emissions reflected in this assessment are based on state and local agency reporting of chromium as "chromium and compounds," individual chromium compounds and chromium ions. Because of the inconsistent reporting, all of the chromium was lumped together for dispersion modeling as "Chromium VI." EPA then based quantitative risk estimates on an assumption that 34 percent of the chromium is hexavalent chromium (which is the most toxic form) based on information from past inventorying efforts.

Description

Chromium exists primarily in two forms: trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)). Trivalent chromium is an essential nutrient required in small amounts for sugar and lipid metabolism in humans and is relatively harmless. In contrast, hexavalent chromium is highly toxic and carcinogenic, posing significant environmental and health risks.

The industrial use of chromium, particularly in metal plating, stainless steel production, leather tanning, and dye manufacturing, can lead to its release into the environment through waste products. Once released, chromium can contaminate soil, air, and water sources. Soil contamination affects plant life, potentially leading to phytotoxicity and altering plant growth and reproductive functions. Water contamination poses serious threats to aquatic life and can affect the quality of drinking water.

Application Areas

Understanding and monitoring chromium levels in the environment are crucial for pollution control and public health safety. Key application areas include:

• Environmental monitoring: Regular testing of soil, water, and air to detect and quantify chromium levels.
• Industrial regulation and waste management: Implementing stricter controls and cleaner production technologies to minimize chromium emissions.
• Remediation technologies: Developing and applying methods to remove or stabilize chromium in contaminated sites, such as phytoremediation, chemical reduction, and encapsulation techniques.

Well-Known Examples

Notable cases of chromium environmental issues include the groundwater contamination in Hinkley, California, famously highlighted in the legal battle by Erin Brockovich. Another significant instance is the contamination near tannery facilities in Kanpur, India, where excessive chromium discharge into water bodies has led to severe ecological and health problems.

Treatment and Risks

The primary risk associated with chromium, particularly hexavalent chromium, is its carcinogenic potential. It has been linked to lung cancer when inhaled and may cause skin ulcers and allergic reactions upon contact. Trivalent chromium, while less harmful, can still pose risks at high concentrations.

Treatment strategies for chromium contamination include:

• Chemical reduction: Converting toxic hexavalent chromium into less harmful trivalent chromium using reducing agents.
• Physical and chemical adsorption: Using materials like activated carbon or specialized resins to remove chromium from water.
• Bioremediation: Employing microorganisms to detoxify chromium-contaminated environments.

Similar Terms

Related environmental concerns involve other heavy metals such as lead (Blei), cadmium (Cadmium), and mercury (Quecksilber), all of which have significant environmental and health impacts due to their toxic properties.

See also: heavy metals.

Weblinks

• architektur-lexikon.de: 'Chrom' in the architektur-lexikon.de (German)

Summary

Chromium in the environment is a double-edged sword; while necessary in small amounts for biological functions, its toxic form, hexavalent chromium, presents severe ecological and health risks. Effective management, monitoring, and remediation efforts are essential to mitigate its impacts on the environment and public health.

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