Crude Oil Biodegradation in Arctic Tundra Ponds

Abstract

The degradation of Prudhoe crude oil was studied in arctic tundra ponds. Contained subponds were treated with oil and/or oleophilic phosphate or inorganic phosphate fertilizers in an attempt to enhance the degradation of the oil by the indigenous microflora. Enumeration studies of water and sediment samples indicated that oil treatment alone did not increase numbers of total heterotrophic or oil-degrading bacteria over a short period (28 days). It was also shown that oil spilled years previously on 2 whole ponds at a high (10 U r n 2) and a low dose (0.24 l/m*) did not alter the microflora quantitatively, except in a small core spilled with oil. Although oil alone seemed to exhibit neither stimulatory nor toxic effects, oleophilic phosphate, added weekly at a concentration of 0.1 mM, significantly stimulated the microflora in the presence or absence of oil. Since equal concentrations of inorganic phosphate failed to induce this effect, the stimulation was attributed to the hydrocarbon portion of the organic phosphate molecule. "C-hydrocarbon mineralization studies demonstrated that the microflora would mineralize the saturate fraction of the oil before the polyaromatic fraction. It was concluded that oleophilic fertilizers may provide a useful tool to enhance the biodegradation of crude oil spilled on oligotrohpic waters. ReSUMk. La dbgredation du "brut" de Prudhoe Bay a et6 etudiee dans des &tangs de toundra arctique. On a trait6 des bassins fermees avec du petrole et/ou avec du phosphate oltophilique ou avec des engrais de phosphate inorganique, dans l'espoir d'acctltrer la degradation du petrole par la microflore indigene. Les techniques enumerkes montraient que le phosphate oltophilique (avec un rapport p6trole/engrais de 20 pour l*), stimulait d'une manikre significative la microflore, soit en presence ou en I'absence de petrole. Ajoute une fois par semaine avec une concentration du 0.1 milligramme, le phosphate inorganique ne stimulait pas les microbes degradant le petrole. Les etudes de min6ralisation d'hydrocarbure en CI4 (glucose) dkmontraient que la microflore mineraliserait la fraction satude du petrole avant la fracture polyaromatique. Les etudes tnumerees dtmontraient que le petrole repandu antkrieurement sur deux &tangs entiers, aux taux de 10 litres/m2 et a faible dose (0.24 litres/mz), n'alterait pas la microflore. Cependant, du pktrole repandu dans un petit bac, deux ans auparavent, avait stimuk, d'une manibre significative, la microflore indigene pour degrader le "brut." On en concluait que les engrais olkophiliques pouvaient fournir un outil utile pour accklerer la bio-degradation du brut rkpandu sur des eaux oligotrophiques.