Sandimirov. S. Pasvik Water Quality Report. Environmental Monitoring Programme in the Norwegian, Finnish and Russian Border Area. Finland, Kuopio: Kopijyva Oy. 2011, №7, p.27-34.

Mg/i 400 350 Figure 4. Distribution of nitrogen compounds. The concentration of total phosphorus in the bottom and surface layers of the lake varies within the limits of 4 - 6 0 |jgPl-1, making an average of 16-17 |jgPl-1 during last two decades (1990-2009). In 2003, the content of total phosphorus in the bottom layers of the Gulf Stream water area located in the northern part of the lake reached 55 |jgP l-1. At present concentrations of total phosphorus are practically equal and at a constant level over the entire Lake Kuetsjarvi. The concentration of phosphates in the Kuetsjarvi Lake varies between 1 -26 jg P l-1, with the average being 3 jg P l-1. Nitrogen For o ligo troph ic w a te r bodies, the content of total nitrogen is usually w ithin the limits o f 3 0 0 ­ 700 jg N l-1. Average concen tra tions o f total n itro ­ gen in the Lake Kuetsja rvi va ry w ithin the limits o f 1 3 4 -3 9 0 j g N l -1, making on average 229 j g N l -1 (Figure 4). The h ighest concen tra tion s o f total nitrogen are seen in the bottom layers and are now unifo rm ly d istribu ted over the entire w a te r area o f the lake. During the last two years from 2008 to 2009, the average concentra tion of total nitrogen over the entire Lake Kuetsjarvi increased from 230 to 280 j g N l -1. The weighted average in dep ths and nitroge concen tra tion s in va rious w a te r areas o f the lake amoun t to 2 6 - 9 5 j g N l -1. In the sou the rn parts of the lake (R ive r Ko losjoki, Lake Sa lm ija rvi, lake outlet) the average concen tra tion o f n itrates is 2 6 - 3 8 j g N l -1. The h ighest concen tra tion s were reg istered in the bottom layers o f the northe rn part o f the lake (sampling sta tion s Wh ite stone, G u lf S tream) - 174 and 320 j g N l -1 respectively. Concentrations of ammonium ions are lower, varying between 3 -7 0 jg N l-1, making an average of 23 jg N l-1. Salinity balance of water The distribution of the principle ions over the entire water area of the Kuetsjarvi lake corresponds to the order: SO42- > HCO3- > Cl-; Ca2+ > Na+ > Mg2+ > K+ and belongs to the class of sulphates. The comparison of contents of cations shows that du­ ring all sampling occasions, calcium was the prevai­ ling cation, making 52 -57% in cation composition (Figure 5). The content of sulphates in water is directly associated with the operation of the Pechenganikel smelter. Sulphates are introduced to the lake with emissions and waste water from the smelter via the Kolosjoki River, therefore, the distribution of these over the water area is uniform. In anion composition, sulphates account for 52-61% (Figure 6). We should also note that during the period of research from 2003 to 2009, this ratio remained at the same level, changing only during some years by an average of 2 -3% . During the last ten years, no significant changes in the content of basic ions have occurred. It was only in 2005 that a short-period decrease in sulphate concentrations took place, however the content of these in the water increased once more following this period. The total mineralization in the Kuetsjarvi Lake averages 69,2 mgl-1, slightly varying throughout the water area of the lake from 43,8 to 90,5 mgl-1. 30 | Centre for Economic Development, Transport and the Environment for Lapland, Publications 7/2011