# Special Issue on Heavy Metals in the Environment--Causes and Consequences
## 2 Heavy Metals in the Environment
Despite the clearly increased heavy metal levels, they do not pose a risk to human health in terms of non-carcinogenic effects. However, increased cancer risk values have been found for metals such as Cd, Cr, and Ni, which poses a health hazard particularly in the case of children. [PERSON] et al. [12] have analyzed the impact of landscape structure on the propagation of heavy metal pollution related to road traffic in the tropical areas of south-eastern China. It has been found that the contamination level of soils used for agricultural purposes is impacted by the distance from roads, the type of land cover, topography, and soil properties. In natural soils, on the other hand, the distance from roads does not influence the level of pollution with heavy metals. A road's place in the road hierarchy (and the resulting traffic intensity) does not impact the concentration of pollutants. The amount of heavy metals accumulating on the leaves of coniferous trees can be used to assess the level of air pollution in urban areas. [PERSON] et al. [13] have assessed the impact of the leaf rinsing method on results of studies on concentration of metals. It has been found that the commonly employed rinsing of needles with water can conceal the actual contamination due to its rather low efficacy (5-50%). [PERSON] and [PERSON] [14] have studied the variation of heavy metal levels in soil profiles within a waste heap of a Zn-Pb mine decommissioned more than 200 years ago. The study objective was to determine the intensity of the vertical migration of heavy metals in soil profiles. This process can pose a threat to groundwater. It has been established that, until now, the most mobile elements, such as Cd and, to a lesser extent, Zn, have migrated several dozen centimeters down the soil profiles. This occurs primarily in acidic soils that are poor in organic matter. The authors conclude that spontaneous reforestation is a good way of stabilizing the heap material and limiting the contamination of groundwater. Long-term monitoring of such sites is necessary, however. In the case of soils, immobilizing heavy metals that penetrated into the soil as a result of human activity is a major challenge. While conducting experimental research, [PERSON] et al. [15] have analyzed the impact of various additives (carbon nanotubes, clay, and Portland cement) on the mobility of Pb, Cu, Ni, and Zn in contaminated soils. Their findings indicate that these additives increase the soil's natural capacity to bind and retain heavy metals. Therefore, they can be used for the remediation of soils contaminated with heavy metals. Phytoextraction is the topic of a study by [PERSON] et al. [16] who have conducted quantitative research on the possibility of removing heavy metals through the cultivation and harvesting of _Arundo donax_ L. grass. It has been found that 3.8 kg/ha Zn, 2.1 kg/ha Cu, and 0.007 kg/ha Cd can be removed (third year of cultivation). At the same time, according to the authors, the harvested grass can be used for power generation. This indicates the prospects of improving the condition of the environment by removing contaminants while reducing the consumption of fossil fuels and thus reducing the emissions of harmful substances. This research received no external funding. This special issue would not have been completed without the hard work and commitment of the authors, reviewers, and editorial team. I would like to thank the authors for their valuable submissions, the reviewers for their professional reviews, and the _Applied Sciences_ journal team for managing the process of preparing the issue. The author declares no conflict of interest.