Soil pollution is one of the main threats affecting soil health worldwide (FAO and ITPS, 2015). However, soil pollution is unique than other threats such as erosion or salinization: it is difficult to perceive with the naked eye, and its effects are only visible when the level of pollution causes acute effects on the environment and human health (Rodríguez Eugenio, McLaughlin and Pennock, 2018). Soil has the ability to filter, buffer, retain and degrade contaminants, in which components such as soil organic carbon, organisms, pH or type of clays and other mineral complexes play a key role (Ceci et al., 2019; Mongwe and Fey, 2004).
Human activities over thousands of years have left a legacy of polluted soils worldwide. Improper disposal of hazardous and urban waste on soil, and exploitation of soil such as urban sprawl, industrial and transport activities, mining, military activities and armed conflicts, and unsustainable agricultural practices are the main sources of soil pollution caused by human activities (Rodríguez Eugenio, McLaughlin and Pennock, 2018). These activities release a wide variety of contaminants into the environment, which are often found in the same place forming a cocktail of contaminants (Chen et al., 2015). The different contaminants produce adverse effects on the health of ecosystems, which can cause changes in individuals and populations and even the death and disappearance of organisms from a given place (Mann, 2011; Saaristo et al., 2018). Humans are also affected by soil contaminants, with effects ranging from acute toxicity to chronic illnesses such as cancer to acutely lethal diseases (Landrigan et al., 2018).
Frequently, soil pollution caused by anthropogenic activities is not limited to a well-delimited area (point-source pollution) but covers large areas (diffuse pollution), that, in some cases, can transcend national boundaries. Virtually all countries and regions of the world have polluted soils, although their extent, dominant contaminants and level of pollution vary significantly depending on the level of industrialization and the main sources of pollution (FAO and ITPS, 2015).
The cost of remediating polluted soils is high, both economically and environmentally, and requires advanced technologies. Especially in the case of diffuse pollution affecting large areas, management practices aimed at reducing the risk and entrance of contaminants into the food chain are applied. Researchers and remediation companies are now investing in the development of nature-based technologies that enable environmentally sound and sustainable remediation (Duarte, Cachada and Rocha-Santos, 2018). Integrated pest management, wastewater treatment, a sustainable circular economy to revalue waste, safe production techniques, implementation of tools such as the Voluntary Guidelines for Sustainable Soil Management (VGSSM) or the International Code of Conduct for the Sustainable Use and Management of Fertilizers (Fertilizer Code), and the application of pollution standards for small and medium enterprises are some of the measures we need to address soil pollution. However, such interventions must go hand in hand with significant changes in consumption and production patterns, legislation and subsidy policies (Mackie and Haščič, 2019).
At the third session of the United Nations Environment Assembly, governments, the private sector and civil society collectively made a pledge to make our planet cleaner (UNEA, 2018). They committed to fostering more sustainable consumption and production patterns and making more efficient our use of resources. While we have some way to go, much is already happening. We need to continue to learn from the innovators and policy leaders who are demonstrating success and help the process of bringing knowledge and solutions to communities in need across the world.
Increasingly vocal and organized groups/associations/soil-advocacy groups are interested in being part of this global conversation and action. To enable all actors to be part of the action and solution, there is a need for accessible and comprehensive information and data on trends in soil pollution. Information and data on soil pollution are crucial for developing sound, sustainable policies and generating investments in sustainable soil management.