KULL

Fifteen coal mine drainage waters from the Millstone Grit and Coal Measures of Derbyshire and Yorkshire have been hydrochemically compared with other iron- rich waters, from spoil tips, natural springs and lead mine soughs, in the area The coal mine waters typically contained several tens of mgl-1 iron, with a range from 0.1 to 101 mgl-1, and sulphate from 60 to over 1000 mgl-1. The waters are undersaturated with respect to siderite. There is a strong linear correlation between iron and sulphate indicating that pyrite weathering is the dominant source of these parameters, although iron appears to be prefer- entially removed by precipitation or adsorption within the mines. Coal mine water pH values are typically c.6, although one water has a pH of 3.6, contains some 17 mgl-1 aluminium and lacks the saturation relative to gibbsite and kaolinite present in the other waters. The coal mine waters may be net acidic or net alkaline; there is some evidence to suggest that the former are typically derived from unsaturated, underdrained (i.e. drained from underneath the workings) shallow workings and the latter from saturated, overflowing workings. The spoil tip waters are nautral to alkaline and saline. A possible explanation for this is the leaching of residual pore-water brines from the deep (several hundred m) mined strata. The spoil tip leachates are poor in iron, which may be retained as iron hydroxides, sulphates or even siderite within the spoil.

During July 1996, three sources of mine run-off were sampled from the mining complex around Longyearbyen, Svalbard; (i) Pumped discharge of minewater from Mine 3 to Bjørndalen, (ii) Run-off from a spoil tip at Mine 3 in Bjørndalen and (iii) Run-off from a spoil at Sverdrupbyen. One objective of the study was to obtain an indication whether the special climate of Svalbard influences the minewater hydrochemistry. The pumped mine water was found to be a highly alkaline, saline (Na-HCO3-C1) water with a low iron content. It is not known if this point sample is repre- sentative of pumped mine discharge at all times. Its alkaline nature may reflect the usage of large quantities of pulverised limestone in the mine to hinder explosion risk, but it is regarded as being more likely related to the natural hydrochemistry of the deep, sub-permafrost water entering the deepest levels of the mine.

Det er analysert 24 bergartsprøver, levert av Store Norske Spitsbergen Kulkom- pani. 14 kullprøver fordelt med 11 prøver fra Svea Sentralfelt og 3 prøver fra Gruve 7 ved Longyearbyen samt 10 bergartsprøver over ("heng"), mellom ("mellom- stein") og under ("ligg"). Kullfløtsene er analysert for en rekke hoved- og sporelementer. Innholdet av Hg, Cu, Ni, Pb, As, Cr, V og Se er analysert for å få en vurdering av hvilke konsentrasjoner det kan forventes i kull og berg- artene liggende opp mot kull lagene som det produseres fra. Det er betydelig høyere konsentrasjoner av arsen og tungmetaller i prøvene fra bergarter der ligger opp mot kullfløtsene, spesielt i "heng" og "mellomstein". Det er imidlertid store variasjoneri konsentrasjonene for alle tungmetaller enten i kull, "heng", "mellomstein" eller "ligg" prøvene. As forekommer i større konsentrasjoner med verdier opp til ca. 225 mg/kg bergart. Denne undersøkelse bekrefter høye As konsentrasjoner i tidligere miljøundersøkelser. Undersøkelse av arsen og tungmetall konsentrasjoner i kull og bergarter som ligger opp mot kull fløtsene kan ha betydning for den mulige spredning av tungmetaller til miljøet fra lokale bergarter og ikke minst fra den lokale bruk, enten gjennom gruvevirksomhet eller lokal anvendelse av bl.a. kull i energiproduksjonen i Longyearbyen og restmateriale fra gruvevirksomheten (skeidestein).