Unresolved complex mixtures of petroleum hydrocarbons in the environment: An overview of ecological effects and remediation approaches

Unresolved complex mixtures (UCMs) of hydrocarbons are the pollutants of serious concern commonly occurring in most of the environments contaminated with petroleum hydrocarbons. UCMs constitute a relatively unidentified group of compounds compared to the well-resolved hydrocarbons that could easily be identified by the modern chromatographic methods. UCMs that accumulate in the environment cause several toxicological effects of ecological significance, and indirectly affect the human health. Despite decades-long efforts to provide adequate information in this area of research, the fate and environmental impacts of UCMs of petroleum hydrocarbons are poorly understood. Techniques for extraction and analysis of UCMs in the environment are very important in their identification and quantification. Also, remediation of toxic UCMs of petroleum hydrocarbons is all the more essential. In fact, UCMs are often neglected in the risk assessments due to lack of proper identification methods and toxicity data. This critical review presents an overview of our current knowledge on the environmental occurrence, sources, separation, and identification methods for UCMs. The ecological toxicity of UCMs toward the biota and the strategies for remediation of the environments contaminated with UCMs have also been discussed in detail.

Automated summary

Unresolved complex mixtures (UCMs) of hydrocarbons are commonly found pollutants in petroleum-contaminated environments, with toxic effects on ecology and indirect impacts on human health. However, understanding of the fate and environmental impacts of UCMs remains limited. Techniques for extraction and analysis of UCMs are crucial for identification and quantification, while remediation of these toxic substances is essential for environmental protection.