Summary:
An analysis of the temporal trends for mercury in Arctic biota is
important for scientists and managers concerned with making
sound science-based policy with respect to changes in Hg in
the Arctic environment. Long-term datasets (ie, comparing
modern with historical or pre-industrial Hg concentrations)
can be used to estimate the relative importance of natural and
anthropogenic Hg inputs in modern biota and the environment,
while short-term datasets (ie, covering the past one to three
decades) illustrate how Hg concentrations have changed in
recent times and suggest likely trends in the near-term future.
In the previous AMAP assessment of Hg in the Arctic
environment (AMAP, 2005), evidence of increasing Hg
concentrations from pre-industrial or historical to more
recent times was presented for Arctic marine biota. Those
trends were shown to continue in recent (short-term) datasets,
primarily in higher-order marine biota from Canada and West
Greenland. In contrast, time series for lower-order marine biota
for Iceland and the European Arctic showed a general pattern
of recently stable or declining Hg concentrations. The reasons
for this spatial difference in trend patterns were not clear.
Data for higher-order marine biota from Europe and Iceland
were lacking as were temporal trend datasets for biota from
Russia and Finland. One of the recommendations resulting
from the previous AMAP assessment was that temporal trend
monitoring of Hg concentrations should be continued in order
to obtain longer and more statistically reliable trend analyzes.
This chapter presents an update of the information available
for both long-term and short-term trends, including a statistical
meta-analysis of recent temporal trends in Hg concentrations
in Arctic biota. The final section presents a discussion, using
case studies, of the possible mechanisms driving the temporal
trends observed.