Heavy metals are known to be among one of the major environmental pollutants, especially in urban
areas, and, as generally known, can pose environmental risks and direct risks to humans. This study deals with
the spatial distribution of heavy metals in different pavement joints in the inner city area of Marburg (Hesse,
Germany). Pavement joints, defined as the joint between paving stones and filled with different materials, have
so far hardly been considered as anthropogenic materials and potential pollution sources in urban areas. Nevertheless, they have an important role as possible sites of infiltration for surface run-off accumulation areas and
are therefore a key feature of urban water regimes. In order to investigate the spatial variability in heavy metals
in pavement joints, a geospatial sampling approach was carried out on six inner city sampling sites, followed
by heavy metal analyses via inductively coupled plasma–mass spectrometry (ICP–MS) and additional pH and
organic matter analyses. A first risk assessment of heavy metal pollution from pavement joints was performed.
Pavement joints examined consist mainly of basaltic gravel, sands, organic material and anthropogenic artefacts (e.g. glass and plastics), with an average joint size of 0.89 cm and a vertical depth of 2–10 cm. In general,
the pavement joint material shows high organic matter loads (average 11.0 % by mass) and neutral to alkaline pH
values. Besides high Al and Fe content, the heavy metals Cr, Ni, Cd and Pb are mainly responsible for the contamination of pavement joints. The identified spatial pattern of maximum heavy metal loads in pavement joints
could not be attributed solely to traffic emissions, as commonly reported for urban areas. Higher concentrations
were detected at run-off accumulation areas (e.g. drainage gutters) and at the lowest sampling points with high
drainage accumulation tendencies. Additional Spearman correlation analyses show a clear positive correlation
between the run-off accumulation value and calculated exposure factor (ExF; Spearman correlation coefficients
(rSP) – 0.80; p<0.00). Further correlation analyses revealed different accumulation and mobility tendencies of
heavy metals in pavement joints. Based on sorption processes with humic substances and an overall alkaline
pH milieu, especially Cu, Cd and Pb showed a low potential mobility and strong adsorption tendency, which
could lead to an accumulation and fixation of heavy metals in pavement joints. The presence of heavy metals in
pavement joints poses a direct risk for urban environments and may also affect environments out of urban areas
if drainage transports accumulated heavy metals. Finally, we encourage further research to give more attention
to this special field of urban anthropogenic materials and potential risks for urban environments. Overall urban
geochemical background values, and the consideration of run-off-related transport processes on pavements, are
needed to develop effective management strategies of urban pavement soil pollution
