Catalogue of Lakes in the Russian, Finnish and Norwegian Border Area = [Каталог озер в приграничном районе России, Финляндии и Норвегии] / Nikolay A. Kashulin, Vladimir A. Dauvalter, Sergey S. Sandimirov etc. - Apatity : Institute of the North Industrial Ecology Problems KSC RAS etc., 2008.

2.9.1. Hydrochemistry The proximity of the sea has a considera ble influence on water quality. The pH of the water in the lake is close to neutral, and the water has a low total mineraliza tion (average 18.6 mg/l) and alkalinity (average 33 |ieq/l). During flood periods the pH falls slightly, i.e. oxidation proc esses do not develop due to the buffer ing capacity of the water. The lake has low concentrations of base cations and anions, with sodium (average 3.43 mg/l) and chloride (average 5.76 mg/l) pre dominating. The annual chemical cycle of the lake is characterized by a slight reduction in the oxidizability and pH of the water during flood periods when the amount of precipitation and inflow of humic wa ter increase. Elevated concentrations of P and N are important criteria when estimating water eutrophication. The concentra tions of and relationships between spe cies of P and N vary according to the season and the dynamics is to a greater extent determined by the level of pro duction and, consequently, the trophic- ity of the water body The average con centrations of total P and total N during the vegetation period are 6 |ig/l and 205 |ig/l, respectively According to the concentrations of mineral nutrients, the lake is classified as oligotrophic. The colour values and the organic matter (2.5 mg/l) and Fe con centrations (average 10.4 |ig/l) are typi cal of small water bodies in the region. During flood periods in the summer the concentrations of P 0 43‘ and N 0 3", which determine the lake productivity, are low. Hydrochemical properties pH 6.40 6.32-6.55 Electrical conductivity, 34 mS/cm 34-37 Ca, mg/l 1.63 1.50-1.70 Mg, mg/l 073 0.68-0.80 Na, mg/l 3.43 3.25-3.58 K, mg/l 0.30 0.27-0.38 HC03, mg/l 2 J. 1.9-2.3 S04, mg/l 4.69 4.58-4.81 Cl, mg/l 5.76 5.24-6.26 Total mineralization. 18.6 mg/l 17.7-19.5 Alkalinity, |aeq/l 33 31-37 Water colour, deg. 6 5-6 NH4, цд/І 6 3-9 N03, цд/І 10 6-13 Total N, (jg/l 118 81-205 P04, цд/І 1 1-1 Total P, цд/І 4 3-6 Fe, цд/І 10.4 6.8-13.0 Cu, цд/І 11 1 . 2 - 2.6 Ni, цд/І 37 3.0-4.5 32 Al, цд/І 24-38 0.4 Pb, цд/І 0 . 2 - 1.0 The low micronutrient concentra tions of the water entering the water body reflect the low level of chemical weathering of the minerals present in the wa tershed area. Although the watershed of Lake Langvatn is relatively distant from the Pechenganickel smelter (distance of 34 km), it is still subjected to the impact of emis sions from the smelter. The main pollutants are sulphur compounds and heavy metals (Ni, Cu, Co, etc.). Despite the fact that emissions from the smelter have been reduced Catalogue o f Lakes in the Russian, Finnish and Norwegian BorderArea