A Study Of Water And Sediment Quality As - TO THE TAR SANDS .ca

High levels of dioxins and furans have been documented in some fish species of
the Athabasca River (MRBB 2004). Dioxins and furans have been detected in Lake
Athabasca sediments (Evans 2000).
There is strong evidence that dioxin exposure is linked to non-Hodgkin’s
lymphoma and soft tissue sarcoma and good evidence that associates dioxin exposure
with Hodgkin’s disease, stomach cancer, altered sex ratio, hormonal changes, menstrual
disorders, and thyroid disorders (Janssen et al. 2004). Skin, liver, and immune system
effects have been observed (Health Canada 2001).
Naphthenic Acids
Naphthenic acids are natural constituents of bitumen that have a relatively high
solubility in water, a low affinity for soil particles, are found in oil sands deposits, and
tend to persist in the water column (McMartin 2003). During bitumen extraction from oil
sands, naphthenic acids are concentrated in tailings. Under natural conditions, naphthenic
acids may enter surface waters through groundwater mixing and through erosion of oil
sands deposits. In oil sand extraction areas, naphthenic acids may enter surface waters
through tailings pond and pipeline leaks. Typically, naphthenic acid concentrations in
industrial tailings ponds are about 100 to 3000 times greater than they are in the
Athabasca River.
Since oil sand deposits can contain hundreds of kinds of naphthenic acids, it is not
known at present which naphthenic acids are the most toxic. Toxicity is more a function
of the content and complexity of the naphthenic acid mixture rather than one of
concentration. Adverse health effects may result from repeated exposure of mammals to
naphthenic acids (Rogers et al. 2002). Much more needs to be learned about the effects of
long-term human exposure to naphthenic acids.
Nitrogen
Nitrogen is a naturally occurring essential element that exists in a variety of
organic and inorganic forms in water. Assimilation of ammonia and nitrate by plants and
microorganisms forms organic nitrogen. Nitrates and nitrites are formed in many ways,
both natural and industrial. Among the natural pathways are nitrification of ammonia and
precipitation of nitric and nitrous oxides. Fertilizer use, release of industrial and
municipal wastes, and leaching of farm animal wastes and septic tanks are major sources
of nitrates. Nitrites can be formed from nitrates by denitrification in sediments that lack
oxygen.
When total nitrogen is in excess it can contribute to eutrophication, odors, and
harmful algal blooms. Nitrate in drinking water may affect human health in the general
population at levels of 100-200 mg/L (McCasland et al., undated). Newborn babies are
more susceptible to nitrite, which can bind to infant hemoglobin and cause an oxygen
transport deficit. Studies linking nitrate in drinking water with cancer have involved high
nitrate levels (>/= 100-200 mg/L), much higher than observed in all but extremely
polluted waters.
Coliform Bacteria
Coliform bacteria are common and widespread within both ecosystems and
organisms. They are usually harmless. Fecal coliforms and Escherichia coli are coliforms
whose presence indicate that water may be contaminated with human or animal wastes.
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