The use of multiple tools in the source
assessment allows the question of “Where
is the source of this nitrogen?” to be
answered. Where sources are unrelated,
mines can motivate for changes to the
regulated limits — as well as provide
the regulators with useful information
on which to take the necessary steps in
addressing non-mine-related impacts to
the water resources. Where mines are
having an impact, strategies can be
focused on the priority sources where
management will achieve the greatest
improvement or offer the best protection to
the regional water resource.
This article is from a paper presented
last year in Finland by SRK’s principal
hydrogeologist, Sarah Skinner, entitled
Helping Mines Find the Real Source of
Nitrates in Water. u
tailings dams may give more of a
sulphate signature.”
This is all part of a multidisciplinary
and multifaceted approach, which
can identify the origin of the source.
Once the source is identified, further
assessments are required to identify
the most practical and cost-effective
management measures.
A conceptual hydrogeological model
is used to identify the direction of
flow and depth to the water table or
topographic surface. Furthermore,
knowing the flow rate allows for the
development of a site salt balance,
which will further inform the water
management around the mine and
allow mines to highlight to management
those sources most likely to affect the
water resources.
isotope, which is indicative of where
the nitrogen originates. Conventional
nitrate analysis only gives quantitative
data and does not discriminate
between sources.
“However, due to the fact that the
ammonium nitrate in fertiliser and in
explosives are essentially the same,
nitrogen isotopes will not be able to
differentiate whether the source is
from fertilisers or mining-related,” she
said. “The next steps in distinguishing
between a fertiliser or explosive source
involve hydro-chemical testing to
establish cation-anion ratios. These
steps make use of deuterium and
oxygen isotopes, as each source will
add something distinctive to the water,
such as chloride — which would give
a nitrate-chloride signature — whereas
innovations
Tools used in the integrated approach.