UN Enviroment Programme

Chapter 5. Global status of soil pollution


This chapter has briefly described the main mechanisms of contaminant remobilisation and transport on a global scale. From the information presented above, the following conclusions can be drawn:

  • - The available information on the sources and distribution of the various contaminants is at the local scale and is almost non-existent at the global scale.
  • - When there are review studies on a regional or global scale, they all highlight the challenge of comparing data due to the lack of harmonization in sample collection and treatment methodologies, methods of laboratory analysis, and even in the definition of the background values against which the measured values should be compared in order to determine whether or not there is soil pollution and therefore a risk to human health and the environment.
  • - There is scarce information on point-source emissions at the national level, especially for developing countries.
  • - Diffuse emissions of contaminants are poorly monitored at the global level except for a few contaminants of high concern. Where a monitoring system exists, it focuses mainly on atmospheric concentrations (air quality), while the other environmental compartments (freshwater, oceans, soils, and living organisms) are generally neglected in national monitoring systems.
  • - Alongside a significant reduction in emissions, it is also necessary to combat climate change, as rising temperatures at higher latitudes can lead to a re-volatilisation of volatile environmental contaminants, which represents a source of secondary emissions to the atmosphere.

In addition, this chapter clearly illustrates that soil pollution is not a local problem. Contaminants can move between countries, regions and even hemispheres, through transport over long distances from the point of emission. To deal with soil pollution on a global scale, it is therefore essential to reduce emissions during production, use and disposal, as well as to manage waste in a sustainable and environmentally sound way. Combating climate change is also key, not only because of its intrinsic effects on the planet and the human livelihood, but also because rising temperatures at the poles can cause a re-volatilization of environmental organic contaminants, providing a source of secondary emissions into the atmosphere. In addition, the loss of soil organic carbon associated with unsustainable management practices and exacerbated by climate change will also contribute to the remobilization of legacy contaminants that remain sequestered in soils.

To understand the sources, fate and global impacts of soil contaminants it is therefore paramount to conduct global surveys and monitoring following a consolidated harmonized sampling scheme and quality control protocol.