Comprehensive assessment of heavy metal pollution in urban environments: A case study from Jelgava, Latvia

Air quality in urban environments has become a critical global issue and the rate of urbanisation is expected to continue rising. This study aimed to identify, on a theoretical basis, the patterns of technogenic background formation and the spatial structure of pollution in the urban environment of Jelgava. The methodology was based on systematic and statistical analyses to assess the sources and levels of pollution in the city. The duration of the study, from the initiation of data collection to the completion of analysis, covered the period from 2017 to 2023, with annual sampling and extensive monitoring conducted throughout this period. The concentrations of heavy metals in various components of the urban ecosystem in Jelgava were found to be within the following ranges: Ni – 20-60 mg/kg, Cu – 40-90 mg/kg, Pb – 30-70 mg/kg, Zn – 100-200 mg/kg. These values correspond to moderate pollution levels typical of urbanised areas in Northern and Central Europe. The highest concentrations were recorded near major roads and industrial zones, whereas peripheral areas were close to background values. It was established that the integrated environmental quality indicators (pollution index = 1.5-2.2, geoaccumulation index = 1-3) characterise Jelgava as a moderately polluted area while maintaining overall ecological stability. Factor analysis revealed that the pollution structure is shaped by two main sources: transport-related emissions (Ni, Cu, Zn – tyre and brake wear, diesel exhaust) and heating-industrial emissions (Pb, Cd – fuel combustion and local emissions from small enterprises). Jelgava can be classified as a moderately polluted yet resilient urban system, where anthropogenic pressure is balanced by natural self-purification mechanisms. The practical value of the study lies in the fact that its findings may be used by municipal environmental and planning authorities to assess risks and manage urban environmental quality.