Researchers have summarized global data on floor loads for the first time. According to this, up to 17 percent of global arable land with toxic metals such as arsenic, lead, cadmium, chrome, cobalt, copper or nickel are contaminated. This endangers our food supply. In addition, up to 1.4 billion people live in areas that are classified as high -risk zone. There, the soil is contaminated with heavy metal quantities that are dangerous for human health and the environment. A corridor that extends from southern Europe to southern China is particularly affected. Where do the metals come from?
Toxic heavy metals and semi -metals get into the soils from natural geological sources as well as from human activities such as mining and other branches of industry. Once brought in, such metals can remain in sound and organic soil layers for decades. This burden on the soil is a significant risk of ecosystems and human health. Because the pollutants affect biodiversity, endanger the water quality and reduce the crop yields. Since the metals accumulate in plants and farm animals, they also threaten our food safety.
Global analysis of the floor load
Earlier studies had already shown that soil pollution is widespread by poisonous metals. However, the worldwide extent was unknown because the studies often only cover individual regions. A team around Deyi Hou from the Tsinghua University in Beijing has now closed this knowledge gap. For this purpose, the researchers have compiled data from 1,493 regional studies with a total of 796,084 soil samples and evaluated with the help of machine learning and modeling approaches. From this, they determined how strongly agricultural soils worldwide are contaminated with toxic metals and where the concentrations exceed the legal security limit values. You compared this data with the global population distribution.
The analysis showed that 14 to 17 percent of arable land worldwide – around 242 million hectares – are contaminated with at least one toxic metal and exceed the limit values for agricultural acreage. The limit values in relation to the environment and human health are exceeded in 6.8 percent of all soils worldwide. Based on their models, Hou and his colleagues estimate that 0.9 to 1.4 billion people live in such high -risk areas in which the soils are contaminated with metals in terms of health.
According to Cadmium, especially in South and East Asia, parts of the Middle East and Africa are most common. “Cadmium crossing in agricultural soils are most powerful in Northern and Central India, Pakistan, Bangladesh, Southern China, in southern Thailand and Cambodia, in Iran, in Turkey, Ethiopia, Nigeria, South Africa, Mexico and Cuba,” writes the team. But also nickel, chrome, arsenic and cobalt exceeded the limit values in different regions.
A transcontinental “corridor” that extends over the entire low wide, wide Eurasia – from southern Europe via the Middle East and South Asia to southern China is particularly heavily contested with pollutants. There, the heavy metals and semi -metals have probably been enriched from the intensive mining since the Bronze Age and distributed through wind and water. Because even the Greeks, Romans, Persians and other early cultures operated in this corridor mining. In addition, there is the natural weathering of metal -rich basic rock such as basalt and slate, which is below the fertile soils. In the identified corridor, the warm climate and the steep mountain leases contribute to this, as the team explains. The comparatively low rainfall also ensure that fewer metals are washed out of the ground.
Floors should be better protected
For the first time, the study summarizes the global risk through heavy metals and semi -metals and shows a previously undetected high -risk zone in which the toxic metals have particularly enriched. However, there is still a data and knowledge gap for some areas such as Northern Russia, Central India and Africa. “There are only limited data for Africa, and the prediction requires further soil samples and analyzes for checking,” write Hou and his colleagues.
In view of the growing demand for many of these metals for wind turbines, solar systems, electric cars and other technologies, the researchers expect that the pollution of the floors will probably worsen in the future. “We hope that the data on global soil pollution presented in this report will serve as a scientific warning for political decision -makers and farmers to take immediate and necessary measures to better protect the valuable soil resources of the world,” said Hou and his colleagues.
Source: Deyi Hou (Tsinghua University) et al.; Science, DOI: 10.1126/Science.adr5214