Pine needles (Pinus sylvestris L.) as a bioindicator of sodium and calcium deposition in the area around pulp and paper mills at Kemi, Northern Finland

* corresponding author. e-mail: risto.poykio@kemi.fi This study presents the most recent data on Na and Ca concentrations in Scots pine (Pinus sylvestris L.) needles sampled in bioindicator surveys carried out in 2009 at Kemi (Northern Finland), as well as at Pietarsaari (Western Finland) in 2007, at Eno (Eastern Finland) in 1994–1996 and in the Jyvaskyla region (Central Finland) in 2006, which are areas with operating pulp and paper mills. Na and Ca concentrations in Scots pine needles at Kemi varied within 7–280 mg/kg (d. w.) and 1 410–5 450 mg/kg (d. w.), respectively. Na concentrations in both C and C + 1 needles at Kemi in 2009 were in good agreement with the values of 31–105 mg/kg (d. w.) and 54–151 mg/kg (d. w.), respectively, observed at Eno. Ca concentrations in C + 1 needles at Kemi were in good agreement with the values of 2 432–5 598 mg/kg (d. w.) observed at Pietarsaari in 2007 and with the values of 2 700–7 900 mg/kg (d. w.) observed in the Jyvaskyla region in 2006, although the highest Ca concentrations – 7 900 mg/kg (d. w.) – in the C + 1 needles in the latter area was obviously higher than the corresponding value of 5 450 mg/kg (d. w.) observed in our study at Kemi.