City of Lahti

Sampling year: 2015

Sample media: topsoil (0–10 cm): aqua regia extractable concentrations from the <2 mm grain-size fraction

Land use: various land use classes in the city centre

The Geological Survey of Finland (GTK) has investigated geochemical baseline concentrations in the city of Lahti. Altogether, 195 topsoil samples were collected from the city centre and suburban areas of Lahti in 2013. The sample sites represented various land uses in urban areas. Samples were collected from 10-cm-deep pits. Arsenic concentrations in the urban soils of Lahti were relatively high compared to most parts of Finland. The upper limit of baseline variation 6 mg As/kg can be applied as the trigger value for urban soil in Lahti.

The concentrations of metals in urban topsoil were usually low. The concentrations of cadmium, cobalt, copper, mercury, lead and zinc in single urban soil samples exceeded the threshold values given in the Decree (VNa 214/2007). In two samples the zinc concentration exceeded the lower guideline value and in one case the zinc concentration exceeded the upper guideline value given in the Decree (VNa 214/2017). Lead concentrations were not elevated along the main roads. Sewage sludge has been applied in green infrastructure in some parts of the city.

The upper limit of baseline variation was lower than the threshold value for all elements except arsenic. Thus the threshold values given in the Decree (VNa 214/2007) can be applied for all elements except arsenic in Lahti.

Report

Hatakka, T., Tarvainen, T., Eklund, M., Luoma, S. & Jarva, J. 2014. Lahden taajama-alueiden maaperän taustapitoisuudet. Geologian tutkimuskeskus. Arkistoraportti 110/2014. 76 s. http://tupa.gtk.fi/raportti/arkisto/110_2014.pdf

Upper recommended limits of baseline variation (SSTP) of selected elements in soils of City of Lahti and the threshold values (Decree 214/2007).