Burrard Inlet Environmental Indicators Report - the BIEAP and ...

Burrard Inlet Environmental Indicators Report February 2008
Results and Trends
Copper and PCB levels are the selected
indicators; however, many other contaminants
also enter Burrard Inlet, where they may have a
negative effect on marine life. Water and
sediment are also monitored for pH (acidity or
alkalinity), dissolved oxygen, suspended solids,
turbidity, other metals (arsenic, cadmium,
chromium, lead, mercury, nickel and zinc)
bacteria (total coliforms, enterococci), chlorineproduced
oxidants, cyanide, ammonia,
hydrogen sulphide, phenol, chlorophenol,
styrene, tributyl tin, 1,2-dichloroethane and
polycyclic aromatic hydrocarbons (PAHs).
Copper concentrations in water
Between 1985 and 2005, 86 samples were
collected from several sites in Burrard Inlet.
Copper levels ranged from 0.0001 mg/L to 0.012
mg/L, with 17 samples (20%) exceeding the water
quality guideline maximum of 0.003 mg/L. Data
were examined for change over time, but no
statistically significant trends were apparent.
Samples from the Central Harbour had the lowest
number of exceedances. These results highlight
the difficulties associated with sampling water,
which can easily miss transient events. In such
cases, copper levels in sediment can provide
more reliable indications of changes over time.
Copper concentration in sediment (mg/kg)
Copper in the surface microlayer
The surface microlalyer, the 50 to 100 micron
thin boundary between water and air is
ecologically important. This is the area where
complex transport processes occur between
the ocean and atmosphere and where larval
forms of many fish and invertebrates live. The
surface microlayer has been shown to contain
contaminants at levels many times higher than
in the water column, which may have an
impact on marine life stages that inhabit this
layer.
In 2000, the Ministry of Environment collected
surface microlayer samples at six locations in
Burrard Inlet (Moore and Freyman 2001).
Copper levels exceeded water quality
guidelines, and were 3 to 30 times higher than
in the underlying water. Levels were greatest
in the Inner Harbour and Port Moody Arm. This
suggests contamination in areas immediately
surrounding point sources, or in embayed
areas adjacent to developed lands, which can
supply atmospheric deposition and runoff.
Based on this limited sampling, it is not
expected that significant microlayer
contamination extends over large areas of
Georgia Strait; however, further monitoring is
required to characterize the environmental
significance of microlayer contamination.
Chart 6-1: Copper Concentrations in Burrard Inlet Sediment (1985 to 2005)
400
350
Central Harbour
False Creek East
Inner Harbour
Copper concentrations in
sediment have decreased
consistently between 1989 and
300
250
Outer Harbour North
Outer Harbour South
Port Moody Arm
Sediment quality objective
2005 as shown in Chart 6-1,
although levels still exceed
guidelines (108 mg/kg, probable
200
effects level) at the Outer Harbour
North and Inner Harbour locations.
150
Levels higher than this guideline
100
put sediment-dwelling organisms
at risk for toxic effects. Historically,
50
levels were highest within the
0
1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006
Inner Harbour and lowest in Outer
Harbour South. The amount of
copper in surface sediments is
decreasing, in part due to decreased levels from permitted effluents, combined sewer overflows
and industrial sources and in part because Metro Vancouver has added buffering to the drinking
water (less acidic drinking water results in less leaching of copper from older household pipes).
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