Investigation of inorganic nutrients and pollutants in private gardens in central Germany using citizen science

Even though private gardens play an important role in food supply, relatively little is known about pollutant concentrations in the corresponding soils. Due to limited access to private gardens, primarily allotment and community gardens are typically examined, which means that front- and backyard gardens are generally not considered. In our study, we examined corresponding soils in central Germany using a citizen science approach. The soil samples were collected in private gardens by the participating citizens. The samples were extracted with aqua regia and analyzed using ICP-AES. However, chromium and nickel concentrations were elevated in a quarter of the samples. High levels of lead and copper were found in one-third of the gardens, and in the case of zinc, in two-thirds of the samples. In addition, samples in which particularly high concentrations of pollutants were found were extracted with ammonium nitrate to examine the substances that are readily available to plants. Here, too, some corresponding limit values were found to be exceeded. Our data thus provide a first basis for a better understanding of the uptake of inorganic pollutants through the consumption of home-grown fruit and vegetables in various types of private gardens.