0.9
B Gully
Parachute Gully
0.2
0.8
0.1
0.7
0
0.6
In-Between Gully
0.2
0.5
0.1
0.4
0
0.3
Bread Truck Gully
0.2
0.2
0.1
0.1
0
0
4.5
5.0
5.5
6.0
4.5
5.0
5.5
6.0
Elevation (m)
Figure 53. Relationship between WP detected in plankton net samples
and peak elevation of flooding event sampled. Open circles are samples
in which no WP was detected.
mer" season. The six WP detections in the May
Table 13. 1995 positive WP results from pond sedi-
analyses were from a total of 12 trap samples,
mentation station cup samples.
whereas the September analyses were from 90
Conc. (g/g)
Time
Area
Station no.
samples. These detected values are consistent with
those of pond sediment traps that were analyzed
May
B-Pond
S-18
0.0671
previously (Lawson et al. 1996).
C-Pond
S-3 Pan N
0.0175
S-3 Pan S
0.0320
In summary, the plankton net samples show
S-8
0.0225
that water is actively transporting WP in the gul-
S-9
0.0260
lies. The origin of the WP is probably contami-
Bread Truck Pond
S-6
0.0268
nated sediments released by erosion of gully walls,
Sept.
Lawson's Pond
LP-4
0.0008
or by resuspension and transport of pond and
Bread Truck Pond
BT-1
0.0003
mudflat sediments of the C, Bread Truck, Lawson's
BT-6
0.0008
and C/D ponds. About one-third of the samples
BT-9
0.0023
acquired during tidal events exceeding 5.1 m in
Racine Is. Pond
RI-2
0.0203
1995 contained WP, similar to 1994. Previous
samples in 1993 from the Bread Truck and Para-
chute gullies proved negative for WP, but were
net samples are recording the erosion of these
collected during tides of less than 5.03 m when
WP-bearing sediments and that the higher con-
the potential for erosion and transport were less.
centrations reflect the lack of mixing and dilution
Resuspension of WP during winter and sum-
that occur during longer distance transport.
mer tells us that we need to consider remobil-
Sediments trapped in cups on pond transects
ization and potential movement of WP to uncon-
revealed some internal movement of WP as the
taminated areas. Data are, however, limited and
result of resuspension of pond and mudflat mate-
the amount of WP migrating within and out of
rials during both the winter and summer seasons
ERF cannot be quantified.
(Fig. 12 and 13; Table 13). Analytical results were
less than 0.1 g/g, but quantities detected were
Further measurements of summer and winter
transport should be made. The high level of WP
generally greater in May samples of "winter" ac-
found in a B-Pond sample this year is a good
tivity than in September samples of the "sum-
60
Previous Page
