Catchment Study

The catchment study (1994-1995) concentrated on eight carefully selected, relatively small (12 to 35 km2) drainage basins located in different geological settings, and at various distances from the pollution point-sources (5-300 km) and from the Barents Sea (40-300 km) (see map). The aim of this study was to shed light on the process and dynamics of element cycling in catchments, and thus to help the interpretation of the regional geochemical mapping results. The main characteristics of the catchments are summarised in the following Table. 



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#  Name    Outlet co- Size  Elevatn  Ann.   Vegetation           Bedrock           Surface cover,
           ordinates  (km2) (m asl)  precip.                                        peculiarities
                                     (mm)*

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RUSSIA
C1 Zapol-  69o27'01"N 19.02 25-373   454    birch forest tundra  gneiss             till, fluvioglacial,
   jarniy  31o03'49"E                                                               outcrop
C2 Monche- 67o50'30"N 22.38 128-507  391    technogenic desert,  dacite, andesite,  till, prone to
   gorsk   32o54'48"E                       birch shrubs         tuffs, gabbro/     erosion
                                                                 norite
C3 Kirovsk 67o32'50"N 20.01 240-1075 502    spruce forest,       nephelinite        till, diluvial/
           33o48'55"E                       mountain tundra                         eluvial
                                            birch forest
C4 Kurka   67o41'25"N 20.49 152-466  502    north taiga spruce   amphibolite,       till, fluvio-glacial
           32o50'14"E                       forest, birch;       gneiss
                                            incipient
                                            deterioration
NORWAY
C5 Skjell- 69o21'25"N 34.56 80-297   422    north taiga pine     andesite, basalt,  till, esker
   bekken  29o27'25"E                       forest, birch        tuffs, 'black
                                                                 shale'
FINLAND
C6 Kirakka 69o35'12"N 11.86 110-200  386    north taiga pine     granite            outcrop, till,
           28o51'46"E                       forest                                  moraine ridge
C7 Naruska 67o21'44"N 20.16 263-490  513    north taiga spruce   gneiss             till, peat, outcrop
           29o22'05"E                       forest
C8 Pallas  68o09'14"N 24.42 303-500  405    north taiga spruce   quartzite          till, peat
           23o52'50"E                       forest
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*from the closest meteorological station (data from 1994)
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Catchment 1 (C1) is located near the Zapoljarniy ore roasting plant (see map and industry). C2 is located near the massive non-ferrous ore smetling industry of Monchegorsk, while C4 is located further downwind. C3 is located near the apatite mine of Kirovsk. C5 is located at some distance from the Nikel smelters, in a direction perpendicular to the main wind direction. C6-8 are located far from any major industrial emission source.

The choice of catchment locations thus affords an identification of geochemical signatures representing different industrial processes (ore roasting, ore smelting, mining), different geological provinces, as well as the distance from the sea and point-source emitters.

Within each catchment, several different localities were sampled for different media. These were snow, rain, stream water, organic stream sediment, terrestrial moss, topsoil and podzol profiles. In addition, ground water and overbank sediments were collected in selected catchments. Of all these media, several were monitored throughout the year 1994 (e.g. stream water). Field methods are described in detail in the report by Äyräs & Reimann (1995), and the main results are summarised in the national reports from Russia (Chekushin et al., 1995), Finland (Äyräs, 1995) and Norway (Reimann, 1995), details of which can be found in the publication list.

The following diagram shows the great differences that exist in the nickel (Ni) content of snow in the different catchments.

NICKEL CONTENT IN SNOW (FILTER RESIDUE)
[NIFSNOW.GIF]
(Diagram: P. de Caritat)
Boxplot diagrams of the Ni content (in parts per billion, or ppb) in snow (filter residue, i.e. particular Ni) in the eight catchments (C1 to C8, as per the Table above). Four different levels of magnification of the vertical scale are necessary to visualise each boxplot in sufficient detail. The spread of data represents the spatial variability within the catchment (snow cores were collected at 9 to 13 open, level localities within each catchment). A boxplot shows the distribution or structure of the data: the closed box, delimited by a lower hinge (the 25th percentile) and an upper hinge (the 75th percentile), contains the two inner quartiles or 50% of the data; the median (the 50th percentile) is represented by the strike inside the box (or a cross when it coincides with one of the hinges); the lower and upper whiskers ('T' bars), in combination with the outlier symbols (squares or plus signs) where applicable, show the spread of the outer quartiles of the data; the notches (short ticks) are a test of significance of medians from different populations or boxes (Tuckey, 1977).

Reference:
- Tuckey, J. W., 1977. Exploratory Data Analysis, Addison-Wesley, New York, 506 pp.