State of the Bay Report 2011-Final.pdf - Anchor Environmental
State of the Bay Report 2011-Final.pdf - Anchor Environmental
State of the Bay Report 2011-Final.pdf - Anchor Environmental
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<strong>State</strong> <strong>of</strong> Saldanha <strong>Bay</strong> & Langebaan Lagoon <strong>2011</strong><br />
Sediments<br />
Basin and <strong>the</strong> multi-purpose quay suggesting that <strong>the</strong> contamination is not <strong>of</strong> natural origin (Figure<br />
5.19). Indeed, both areas are in close proximity to various industrial activities which are likely to be<br />
contributing Cd to <strong>the</strong> system through emissions and stormwater run-<strong>of</strong>f collectively. The second<br />
highest normalized Cd:Al ratio was recorded at BB20 situated at <strong>the</strong> opening to Big <strong>Bay</strong> (Figure 5.19).<br />
This site had a negligible mud content and low over concentration <strong>of</strong> Cd. This indicates a low level <strong>of</strong><br />
anthropogenic input <strong>of</strong> Cd at this site. This is, however, not a cause for concern given <strong>the</strong> exposed<br />
nature <strong>of</strong> <strong>the</strong> site and <strong>the</strong> low Cd concentration. Cd concentrations were relatively high at sites in<br />
Salamander <strong>Bay</strong> and Donkergat, though <strong>the</strong>se did not exceed <strong>the</strong> ERL (Figure 5.20 and Table 5.3).<br />
This result did not correlate with that <strong>of</strong> <strong>the</strong> particle size composition as both sites had a low mud<br />
fraction. This indicates that <strong>the</strong>se sites are not subject to high rates <strong>of</strong> retention and that <strong>the</strong> source<br />
<strong>of</strong> <strong>the</strong> high Cd concentrations was likely to be fairly recent and local to <strong>the</strong>se sites. The relatively<br />
elevated Cd:Al ratio at <strong>the</strong>se sites suggests <strong>the</strong> source was not <strong>of</strong> natural origin. Both sites are<br />
situated in close proximity to <strong>the</strong> Special Forces Regiment <strong>of</strong> <strong>the</strong> South African National Defence<br />
Force (SANDF) who commenced <strong>the</strong> construction <strong>of</strong> a boat yard in 2009. Dredging was conducted in<br />
<strong>the</strong> area in 2009 and 2010. It is likely that <strong>the</strong> dredging activities resuspended Cd accumulations<br />
from deeper sediments.<br />
Table 5.4. Enrichment factors for Cadmium, Copper and Lead in sediments collected from Saldanha <strong>Bay</strong><br />
in 2009 relative to sediments from 1980<br />
Sample Cd Cu Pb<br />
1980 average 0.075 0.41 0.8<br />
Small <strong>Bay</strong> SB1 27.81333 99.37561 29.095<br />
SB2 4.213333 11.86341 7.99125<br />
SB3 2.36 6.143902 17.125<br />
SB8 3.573333 3.580488 6.16875<br />
SB9 5.586667 7.495122 6.9375<br />
SB10 1.4 0.968293 6.665<br />
SB14 16.09333 37.07805 80.17125<br />
SB15 2.853333 3.373171 7.01875<br />
SB16 5.773333 4.9 4.71625<br />
Big <strong>Bay</strong> BB20 4.213333 0.419512 0.31875<br />
BB21 2.72 1.204878 3.39<br />
BB22 5.026667 6.060976 4.535<br />
BB25 1.106667 - 0.21625<br />
BB26 4.373333 0.353659 3.52125<br />
BB29 2.266667 - -<br />
BB30 0.666667 - 0.0075<br />
108<br />
ANCHOR<br />
e n v i r o n m en t a l
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