Sandimirov S.S. Catalogue of lakes in the Russian, Finnish and Norwegian Border Area. Finland, Jyvaskyla: Kopijyva Oy, 2008.

1.9. LAKE PALOJARVI Lake Palojarvi (watershed of the River Pechenga) is located 6 km from the Russian- Norwegian border and 4 km to the north of the town of Zapolyarny, and is a source of drinking water for the local inhabitants. It is a small (area of the lake 2.76 km2), shallow-water (maximum depth 5 m), almost oval lake of glacial origin. The maximum length is 2.8 km and maximum width 2.2 km. The points of maximum depths (5 m) occur throughout the whole water body. The lake belongs to the Paz lake-river system, and is connected to the system by a small stream. According to the landscape type, the watershed area consists of a com­ bination of flat low-lying areas of glaciolacustrine flat lands and tectonic massifs with abrupt outcrops of quaternary deposits, with a height of up to 371.6 m (Maatun- turi fell). The shores of the lake are not high, and are covered by birch stands. The water of the lake is colourless but, during flood periods, the colour ofwater increases to 38 deg. and becomes slightly yellowish. Boulder beds and mudflats occur in the littoral zone. Dark brown silt de­ posits are predominant throughout the whole area of the lake. 1.9.1. Hydrochemistry The lake is one of the most polluted lakes in the Pechenga area owing to its close prox­ imity to the Pechenganikel smelter. Airborne pollution has a considerable impact on the water quality. The water of the lake is close to neutral and the mean total mineralization is 27.0 mg/l and mean alkalinity 141 peq/1. During flood periods the pH of the water falls to 6.39 and then returns to 6.97. The lake has high concentrations of base cations and anions, calcium (av­ erage 3.15 mg/l) and bicarbonate (aver­ age 8.6 mg/l) predominating. Intensive pollution of the lake oc­ curred during the late 1980s to early 1990s when emissions from the smelter were at peak levels. At that time the concentrations of most elements in the water, especially sulphate (up to 8.84 mg/l), Cu and Ni, also reached their maximum. The concentrations of these elements, as well as other elements that characterize the state of the water, are currently still high. The annual chemical cycle of the Hydrochemical properties pH 6.71 6.39-6.97 Electrical conductivity, mS/cm 43 39-58 Ca, mg/l 3.15 2.62-4.19 Mg, mg/l 1.21 1.06-1.67 Na, mg/l 2.95 2.61-3.73 K, mg/l 0.43 0.36-0.59 HC03, mg/l &6 7.0-12.3 S04, mg/l 6.49 5.46-9.60 Cl, mg/l 4.19 3.56-5.67 Total mineralization, mg/l 27.0 23.1-37.4 Physico-geographical characteristics Watershed River Namajoki— River Pechenga Latitude 69°27.076' Longitude 30°45.356' Height above sea level, m 155.6 Maximum length, km 2.8 Maximum width, km 2.2 Maximum depth, m 5 Area, m2 2.76 Watershed area, km2 86.0 Study period 1990-2007 Catalogue o f Lakes in the Russian, Finnish and Norwegian BorderArea