Geochemical baselines
Sampling years: 2008 – 2009
Sample media: humus: concentrated nitric acid extraction from the <2 mm grain-size fraction; topsoil (0–25 cm) and subsoil: aqua regia extractable concentrations from the <2 mm grain-size fraction
Soil parent materials: sand 44 profiles, till 94 profiles, clay 33 profiles
The Geological Survey of Finland (GTK) has studied geochemical baselines in the Häme region using topsoil, subsoil and humus samples collected in 2008–2009. Altogether, 171 sample profiles represented the most common mineral soil types of the region: 44 sample pits were dug in sand and gravel formations, 94 profiles were investigated in glacial till and 33 in fine-grained sediments (clayey deposits). Aqua regia extraction was used for mineral soil samples and concentrated nitric acid for humus samples. In addition to element concentrations, pH and loss on ignition (LOI) values were measured for both humus and mineral soil samples. Separate carbon measurements were taken from mineral samples.
Arsenic concentrations in soil samples were higher than the As content in other parts of Finland. The upper limit of baseline variation was higher than the threshold value of 5 mg/kg given in the Decree on the Assessment of Soil Contamination and Remediation Needs (VNa 214/2007) in all soil types. The highest arsenic concentrations in soil were determined from samples taken in northwest Häme, which belongs to geochemical arsenic province of Southern Pirkanmaa (As province 4). Arsenic concentrations in glacial till were northwest Häme were even higher than in some glacial till samples in Southern Pirkanmaa (Southern Tampere region).
The concentrations of most of the other trace metals than As were relatively high in the northern part of the Häme region, but the calculated values for the upper limit of baseline variation were lower than the threshold values given in the Decree (VNa 241/2007).
Report:
Tarvainen, T. 2010. Hämeen maaperän taustapitoisuudet. Esiselvitys. Geologian tutkimuskeskus, arkistoraportti S41/2010/22. 24 s. http://tupa.gtk.fi/raportti/arkisto/s41_2010_22.pdf
Statsitics:
The Häme region is divided into several arsenic and metal provinces. The value of the upper limit of baseline variation can be calculated using the 'Statistics' tool in the map service.Sampling year: 2010
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 and suburban areas
The Geological Survey of Finland (GTK) has investigated geochemical baseline concentrations in the city of Hämeenlinna. Altogether, 400 topsoil samples were collected from the city centre and suburban areas of Hämeenlinna in 2010. The sample sites represented various land uses in urban areas. Samples were collected from 10-cm-deep pits according to the guidelines of the EuroGeoSurveys urban geochemistry sampling protocol. Aqua regia extractable concentrations of 53 elements as well as the total carbon content and soil pH were determined from all samples. The sampling sites were selected in co-operation with the environmental authorities of the city of Hämeenlinna. Arsenic concentrations in the urban soils exceeded the guideline value of 5 mg/kg given in the Government Decree on the Assessment of Soil Contamination and Remediation Needs (VNa 214/2007). The upper limit of baseline variation was 25 mg As/kg in the city centre and in the Kalvola suburban area, while the baseline value for other parts of Hämeenlinna was 9 mg As/kg. The baseline concentration of cobalt also exceeded the guideline value in the urban soils of the city centre and Kalvola. The estimated upper limit for baseline variation was 21.5 mg Co/kg.
The concentrations of several metals in urban soils were compared with concentrations in natural soils. Cadmium, cobalt, chromium, copper, lead, nickel, zinc, vanadium, silver, gold, carbon, calcium, manganese and strontium showed higher concentrations in urban soils than in the surrounding natural environment.
Report:
Tarvainen, T. 2011. Hämeenlinnan taajamageokemia. Hämeenlinnan ympäristöjulkaisuja 17. 30 s.
http://www.hameenlinna.fi/pages/215561/Hämeenlinnan_taajamageokemia.pdf
Statistics:
The City of Hämeenlinna belongs to several arsenic and metal provinces. The following statistics are published in the report:
Hämeenlinna city centre and Kalvola
Other suburban areas