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The Effects of Road Transport on Freshwater and Marine Ecosystems

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86<br />

Although a range <str<strong>on</strong>g>of</str<strong>on</strong>g> factors influence the toxicity exhibited by a given c<strong>on</strong>taminant, the key factor that<br />

c<strong>on</strong>trols the toxicity arising from c<strong>on</strong>taminants in sediments is acid volatile sulphide (AVS). AVS is an<br />

important c<strong>on</strong>troller <str<strong>on</strong>g>of</str<strong>on</strong>g> toxicity as it influences the amount <str<strong>on</strong>g>of</str<strong>on</strong>g> a given metal in the pore water <str<strong>on</strong>g>of</str<strong>on</strong>g> the<br />

sediments. It is the pore water that benthic organisms are directly exposed to. AVS is not c<strong>on</strong>sidered<br />

appropriate for the assessment <str<strong>on</strong>g>of</str<strong>on</strong>g> Hg <strong>and</strong> Cu that are associated with other phases <str<strong>on</strong>g>of</str<strong>on</strong>g> sediment. It has<br />

been shown that the molar ratio <str<strong>on</strong>g>of</str<strong>on</strong>g> metals (extracted at the same time as AVS) to AVS is related to<br />

toxicity. When lower than <strong>on</strong>e, no acute toxicity (mortality greater than 50%) was found. When the ratio<br />

was greater than <strong>on</strong>e, then toxicity was observed. Overall, it is c<strong>on</strong>sidered that AVS can be utilised to<br />

predict whether metal c<strong>on</strong>taminated sediments are acutely toxic (Di Toro et al. 1992). <str<strong>on</strong>g>The</str<strong>on</strong>g> EPA has<br />

utilised the SEM <strong>and</strong> AVS data to categorise sediments in the US nati<strong>on</strong>al sediment quality survey into<br />

Tier <strong>on</strong>e or two categories.<br />

<str<strong>on</strong>g>The</str<strong>on</strong>g>re are a variety <str<strong>on</strong>g>of</str<strong>on</strong>g> tests available for the testing <str<strong>on</strong>g>of</str<strong>on</strong>g> sediment toxicity. <str<strong>on</strong>g>The</str<strong>on</strong>g>se have in many instances<br />

been developed as st<strong>and</strong>ard tests by regulatory agencies <strong>and</strong> have been utilised for example for the<br />

assessment <str<strong>on</strong>g>of</str<strong>on</strong>g> the toxicity <str<strong>on</strong>g>of</str<strong>on</strong>g> dredged sediment to be disposed at sea. Hickey (1998) provides a review<br />

<str<strong>on</strong>g>of</str<strong>on</strong>g> tests utilised in New Zeal<strong>and</strong> to assess the toxicity <str<strong>on</strong>g>of</str<strong>on</strong>g> freshwater sediments. One <str<strong>on</strong>g>of</str<strong>on</strong>g> the most<br />

comm<strong>on</strong>ly tests used is the amphipod Chaetocorophium cf. lucasi acute survival <strong>and</strong> chr<strong>on</strong>ic growth test.<br />

Toxicity tests can provide informati<strong>on</strong> <strong>on</strong> the potential toxicity <str<strong>on</strong>g>of</str<strong>on</strong>g> sediments associated with stormwater<br />

discharges from urban <strong>and</strong> isolated roadways. <str<strong>on</strong>g>The</str<strong>on</strong>g> results however, do not provide direct informati<strong>on</strong> <strong>on</strong><br />

the cause <str<strong>on</strong>g>of</str<strong>on</strong>g> the toxicity arising from the c<strong>on</strong>taminati<strong>on</strong>. Toxicant identificati<strong>on</strong> evaluati<strong>on</strong> (TIE) is an<br />

additi<strong>on</strong>al method that provides informati<strong>on</strong> <strong>on</strong> the relative toxicity <str<strong>on</strong>g>of</str<strong>on</strong>g> fracti<strong>on</strong>s <str<strong>on</strong>g>of</str<strong>on</strong>g> complex mixtures <str<strong>on</strong>g>of</str<strong>on</strong>g><br />

toxicants.<br />

In New Zeal<strong>and</strong>, sediment toxicity tests were performed <strong>on</strong> sediments collected from the inlet <strong>and</strong> outlet<br />

<str<strong>on</strong>g>of</str<strong>on</strong>g> the stormwater p<strong>on</strong>ds <strong>and</strong> the s<strong>and</strong> filter at the UNITEC carpark in Mt Albert, Auckl<strong>and</strong> (Nipper et al.<br />

1995). Tests c<strong>on</strong>ducted included:<br />

<br />

<br />

<br />

<br />

<br />

10 day acute mortality test using the amphipod Chaetocorphium cf. lucasi.<br />

10 day acute mortality test using the clam Sphaerium novaezel<strong>and</strong>iae.<br />

10 day acute mortality test using the worm Lumbricus variegatus.<br />

20 day mortality <strong>and</strong> reproducti<strong>on</strong> test using the worm Lumbricus variegatus.<br />

Assessment <str<strong>on</strong>g>of</str<strong>on</strong>g> re-burial ability <str<strong>on</strong>g>of</str<strong>on</strong>g> the clam Sphaerium novaezel<strong>and</strong>iae following the acute mortality<br />

test.<br />

<str<strong>on</strong>g>The</str<strong>on</strong>g> amphipod survival test results obtained by Nipper et al. (1995) indicated that the sediments that<br />

accumulated in the UNITEC carpark p<strong>on</strong>d were toxic with zero to low survival in all tests c<strong>on</strong>ducted using<br />

sediment samples from both the inlet <strong>and</strong> outlet. <str<strong>on</strong>g>The</str<strong>on</strong>g> s<strong>and</strong> filter test results showed no significant acute<br />

toxicity. This reflected the high proporti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> original s<strong>and</strong> in the filter material sample <strong>and</strong> the relatively<br />

low c<strong>on</strong>taminant c<strong>on</strong>centrati<strong>on</strong>s in the sediment sample from the filter.<br />

No significant differences were found in the Sphaerium novaezel<strong>and</strong>iae acute survival tests between<br />

stormwater p<strong>on</strong>d sediments <strong>and</strong> reference sediments in the toxicity tests c<strong>on</strong>ducted by Nipper et al.<br />

(1995) due to the low survival <str<strong>on</strong>g>of</str<strong>on</strong>g> the clams in the reference sediments. Reburial rates were lower in the<br />

sediment from the lower UNITEC carpark p<strong>on</strong>d compared to the reference mud sample but not compared<br />

to the reference s<strong>and</strong>. Worm 10 day survival <strong>and</strong> reproducti<strong>on</strong> differed between the UNITEC carpark inlet<br />

sediments <strong>and</strong> the reference sediments. In the 20 day test, survival <strong>and</strong> reproducti<strong>on</strong> differed <strong>on</strong>ly<br />

between the results for the p<strong>on</strong>d outlets <strong>and</strong> the reference sediments (Nipper et al. 1995, Hickey 1999).<br />

A number <str<strong>on</strong>g>of</str<strong>on</strong>g> studies have been carried out internati<strong>on</strong>ally that have provided informati<strong>on</strong> <strong>on</strong> the toxicity <str<strong>on</strong>g>of</str<strong>on</strong>g><br />

sediments c<strong>on</strong>taminated by road run<str<strong>on</strong>g>of</str<strong>on</strong>g>f (e.g., Maltby et al. 1995a,b). Boxall & Maltby (1995) examined<br />

the toxicity <str<strong>on</strong>g>of</str<strong>on</strong>g> sediment c<strong>on</strong>taminated with road run<str<strong>on</strong>g>of</str<strong>on</strong>g>f using the TIE process. <str<strong>on</strong>g>The</str<strong>on</strong>g> sediments examined<br />

came from a site adjacent to a stormwater outfall <strong>on</strong> the M1 motorway (Engl<strong>and</strong>). <str<strong>on</strong>g>The</str<strong>on</strong>g> toxicity <str<strong>on</strong>g>of</str<strong>on</strong>g> the<br />

fracti<strong>on</strong>s collected were assessed using freshwater amphipod (Gammarus pulex, 14 day mortality) <strong>and</strong><br />

the bacteria Photobacterium phosphoreum (Microtox bioassay). Toxicity was dem<strong>on</strong>strated to both test<br />

Kingett Mitchell Ltd<br />

Resource & Envir<strong>on</strong>mental C<strong>on</strong>sultants

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