The Content of Heavy Metals in the Drainage Ditches by Communication Routes

Heavy metals are among the most dangerous pollutants roadside. Heavy metal ions of automobile origin enter the soil, among other things, with the solid particles PM (particulate matter), on which they are adsorbed. In view of the increasing number of vehicles on our roads each year, it is extremely important to determine the risk of heavy metal emissions caused by communication nowadays. In the studies assessing the impact of vehicles on soil pollution with heavy metals much attention is given to urban areas but few works are dedicated to soil pollution in open (agricultural) and forest areas, while maintaining the lowest possible course of anthropogenic impact. In addition, these works apply various methods of soil sampling (different depths and distance from roads). It also happens that no soil samples are taken from the two levels, making it impossible to assess the degree of heavy metals enrichment. The aim of this study was to determine the soil pollution with heavy metals (Cd, Pb, Ni, Zn, Cu) in the drainage ditches along the communication routes in Roztocze National Park (RNP) and the Landscape Park Foothills (LPF). It shows the contents of the studied heavy metals and pH determination in soil samples taken from two levels (0-5 cm and 5-20 cm), which allowed to identify the anthropogenic origin. Six road sections selected on the basis of measuring similar traffic congestion on the routes were chosen. The content of the analyzed heavy metals elements in the soil samples tested, ranged as follows: cadmium <0,23-0,86 mg kg(-1) a.d.m., lead 10,22-29,0 mg kg(-1) a.d.m., nickel, 4,0-37.3 mg kg(-1) a.d.m., Zn 40-256 mg kg(-1) a.d.m., copper 4,0-23,0 mg kg(-1) a.d.m.. The obtained results revealed that cadmium, lead and copper in all analyzed soil samples did not exceed concentration limits in areas subject to environmental protection. However, nickel and zinc concentration slightly exceeded the limit. In addition, higher content of heavy metal elements discovered in the subsurface soil layer, taken from the depth of 0-5 cm, proves both their anthropogenic, automotive origin and the enrichment of soil. The overall decrease in heavy metal content with the depth in the soil profile and increase in traffic congestion indicate the relationship with the automotive environmental pollution. The role of drainage ditches as a barrier against further spread of dust produced during the operation of transport infrastructure turned out to be essential. Sealing and guttering of drainage ditches in the protected areas are necessary in order to protect the soil from excessive amounts of chemical contaminants.