The Effects of Road Transport on Freshwater and Marine Ecosystems

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118 International studies have shown variable toxicity from receiving water sediment to aquatic biota. <strong>The</strong> New Zealand studies that have been carried out have shown that the particulate matter (from road stormwater) settling in pond systems has the ability to cause adverse toxicity to test organisms. Available information indicates that elevated concentrations <strong>of</strong> dissolved or particulate metals in stormwater or stream water have the potential to result in bioaccumulation in freshwater biota. Information shows that concentrations <strong>of</strong> Cu, Pb and Zn have been reported in a range <strong>of</strong> species but not consistently between species and feeding groups. Although accumulation has been identified, there is no information as to the potential for any adverse effects arising from that uptake. It has been demonstrated that the response to elements such as Cu and Zn (biological functions) differs to that <strong>of</strong> Pb (non essential). <strong>The</strong>re is little data available in relation to effects derived from trace elements such as Mo and Sb emitted by motor vehicles. Significant bioaccumulation is however unlikely. For some elements such as Sb and Pd for which there appears to be no nutritional requirement, uptake in a variety <strong>of</strong> organisms has been demonstrated. <strong>The</strong> effects <strong>of</strong> bioaccumulation are however unknown at a cellular and whole organism level. <strong>The</strong>re is little information that indicates that any freshwater species (e.g., eel, watercress) exposed to those elements derived from road run<strong>of</strong>f would bioaccumulate those elements to the point that would result in their unsuitability for human consumption. <strong>The</strong>re is little information in New Zealand on the specific uptake <strong>of</strong> organic compounds by freshwater macro-invertebrates or fish that relates specifically to road stormwater run<strong>of</strong>f. Work undertaken on the uptake <strong>of</strong> PAHs in a car park stormwater pond demonstrated some uptake. <strong>The</strong>re are a wide range <strong>of</strong> organic compounds emitted by vehicles and present in stormwater discharged to freshwater environments that have potential for bioaccumulation. <strong>The</strong> key groups are the PAHs and substituted PAHs. Although uptake <strong>of</strong> these key groups <strong>of</strong> contaminants has been identified no adverse effects <strong>of</strong> bioaccumulation appear to have been identified and bioaccumulation is not likely to occur to a level that would result in adverse effects to the suitability <strong>of</strong> fish such as eel becoming unsuitable for consumption. <strong>The</strong> role that the uptake <strong>of</strong> organic compounds play in the health <strong>of</strong> freshwater organisms at a cellular and whole organism level is not clear. <strong>The</strong>re are a complex range <strong>of</strong> organic compounds emitted to freshwaters from a variety <strong>of</strong> sources. Many compounds are emitted from multiple sources (vehicles and non-vehicle sources). 8.6 Marine environments Stormwater discharges from roads and urban catchments typically discharge particulate material that settles adjacent to the stormwater outfall. <strong>The</strong> presence and extent <strong>of</strong> the distribution <strong>of</strong> that material is dependent upon the hydrodynamics <strong>of</strong> the environment at the point <strong>of</strong> discharge. If the physical environment is depositional in nature then material may accumulate adjacent to the outfall. <strong>The</strong>re is potential for that material to cause some local change in sediment physical characteristics and hence habitat. <strong>The</strong> source <strong>of</strong> the material is principally the wear <strong>of</strong> road surface material not motor-vehicles. <strong>The</strong> discharge <strong>of</strong> urban and roadway stormwater has the potential to cause changes in the quality <strong>of</strong> the sediment environment immediately adjacent to the point <strong>of</strong> discharge. <strong>The</strong> extent <strong>of</strong> the area is dependent upon the size <strong>of</strong> the discharge and the nature <strong>of</strong> the discharge environment (e.g., estuary or open coast). <strong>The</strong> ‘halo’ around the discharge location may be such that it results in a depauperate fauna consisting <strong>of</strong> hardy or opportunistic species. <strong>The</strong> change in faunal composition appears to be caused by changes in the physical composition <strong>of</strong> the sediment coupled with changes in the chemistry <strong>of</strong> the sediments (ammonia, sulphide etc.,). Examination <strong>of</strong> contaminant concentrations immediately around the discharge points for stormwater run<strong>of</strong>f from roads and urban areas shows that concentrations <strong>of</strong> contaminants in sediments are typically elevated. Concentrations in both intertidal and subtidal Kingett Mitchell Ltd Resource & Environmental Consultants
119 sediments can rise above sediment quality guidelines and triggers. For most smaller discharge points haloes <strong>of</strong> metal concentrations are generally restricted to 10-20 m. In the wider areas <strong>of</strong> urban estuaries and harbours sediments <strong>of</strong>ten contain elevated concentrations <strong>of</strong> metal and organic contaminants. In locations such as the Waitemata Harbour it appears that all <strong>of</strong> the surface sediments in harbour are contaminated to some degree. In depositional environments the concentration <strong>of</strong> elements such as Cu exceed sediment quality guidelines. Within New Zealand such effects are likely to be restricted principally to depositional environments adjacent to urban areas. However, stormwater discharges from roads and smaller urban centres to smaller estuaries will have comparable effects but on a smaller scale. Overall, the contribution that motor vehicles have to sediment contamination is identifiable where the discharge is derived from an isolated road. In urban areas, the contribution from vehicles to sediment contamination adjacent to outfalls and within estuaries and harbours will be dependent upon the ratio <strong>of</strong> the loads contributed by vehicle sources and other urban sources and activities. Toxicity testing carried out using stormwater solids and marine organisms in New Zealand has shown that the toxicity <strong>of</strong> stormwater is variable. <strong>The</strong> testing indicated that some dilution <strong>of</strong> stormwater sediments would be required to ensure that no water column toxicity after discharge. It was noted in that study that toxicity was lower than expected. Contaminants other than metals were suggested as having a strong involvement in toxicity. Work undertaken in the United States has shown that toxicity to sensitive marine species can occur in nearshore coastal areas in situations where stormwater discharges are not diluted sufficiently. Studies have determined that a dilution <strong>of</strong> typically 90% is required to eliminate toxicity to sensitive species. As such, toxicity may occur in locations where dilution is poor. Such locations include embayments and estuaries in harbours and the estuaries <strong>of</strong> rivers. Given the relatively small size <strong>of</strong> most New Zealand road and urban catchments road and urban catchments, discharges volumes from open coastal stormwater outfalls are typically small. Toxicity testing <strong>of</strong> stormwater sediments has shown that adverse effects can be obtained in tests. This would suggest that adjacent to outfalls where deposited sediment may accumulate toxicity may occur. <strong>The</strong> toxicity may arise from the elevated concentrations <strong>of</strong> key contaminants such as Zn. Adverse effects may also be due to elevated concentrations <strong>of</strong> sulphide and ammoniacal nitrogen in those sediments or other constituents. In depositional areas such as estuaries and harbours in New Zealand, where sediment contaminant concentrations are elevated, there is no direct evidence <strong>of</strong> sediment related toxicity. <strong>The</strong>re does not appear to be any evidence at the present time that elevated concentrations <strong>of</strong> key elements (e.g., Zn) that are derived in part from vehicle emissions being a causal agent in toxicity or changes in benthic biological community composition. <strong>The</strong>re are currently no specific tools for isolating the effects <strong>of</strong> roadway stormwater discharge on the marine environment. However, in the case <strong>of</strong> isolated roadway discharges, traditional quantitative sampling and assessment tools that assess abundance, diversity and other metrics are capable <strong>of</strong> identifying effects <strong>of</strong> discharges (variability permitting). Information in New Zealand has shown that build-up <strong>of</strong> contaminants occurs adjacent to urban stormwater outfalls discharging to the marine environment and in intertidal areas adjacent to roads. Most studies carried out to-date in New Zealand have dealt with the identification <strong>of</strong> possible effects <strong>of</strong> urban run-<strong>of</strong>f on coastal ecosystems. <strong>The</strong> studies have indicated that urbanisation as a whole results in adverse changes to the diversity <strong>of</strong> the biological communities present. Further specific research would need to be carried out to isolate the potential effects <strong>of</strong> road and highway run-<strong>of</strong>f by carrying out effects studies in locations where run<strong>of</strong>f from roads and highways was isolated from the confounding effects <strong>of</strong> general urban run<strong>of</strong>f. If the adverse effects arising from urban run<strong>of</strong>f are attributable to elements such as Zn, then it is likely that roads and motor vehicles will contribute their proportional share <strong>of</strong> the adverse effect observed. <strong>The</strong> proportion <strong>of</strong> that effect will vary from location to location. At this stage the proportion <strong>of</strong> any observed effect is not known (even when identified on a contributed load basis). Kingett Mitchell Ltd Resource & Environmental Consultants
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The Effect
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ii 4.2 Particulates in Urban Run<st
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iv 7. IDENTIFICATION OF ENVIRONMENT
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vi MW Molecular weight N Nitrogen N
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2 1. Moncrieff, I.; Kennedy, P. 200
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6 mg/kg) and Zn (25-34,500 mg/kg).
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22 sample of overs
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24 suspension and that carried as b
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26 Figure 4.1 - Variation in the co
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28 Figure 4.2 - Variation in the co
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30 Metal Cu Cd Pb Zn Table 4.6 - Su
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32 probably reflect lower traffic d
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34 (1995) provide a general review
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36 Further data can be found in the
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38 by ARC (1994) indicated that TPH
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40 Cations/Anions Common ionic cons
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42 Catchpits Between the street sur
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44 5 PATHWAYS & FATE OF CONTAMINANT
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48 crystalline species present were
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50 Figure 5.1 - Percentage
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52 short (e.g., < 1 day). In water,
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54 5.4.2 Dispersion Dilution and di
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56 5.6 Summary The
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58 6.2 Freshwater Ecosystems 6.2.1
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60 General Assessment Tools Commonl
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62 3. Increasing sediment inputs. 4
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64 considered that taxa richness wa
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66 Freshwater macro-invertebrate me
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Page 82 and 83: 72 one factor used to classify orga
Page 84 and 85: 74 Zinc Measurement of</str
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Page 88 and 89: 78 minute; sub-mitochondrial partic
Page 90 and 91: 80 Toxicity tests have undertaken u
Page 92 and 93: 82 High molecular weight PAHs are t
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Page 98 and 99: 88 Bioaccumulation can be assessed
Page 100 and 101: 90 Figure 6.2 - metal concentration
Page 102 and 103: 92 6.5.3 Bioaccumulation of
Page 104 and 105: 94 Water Stormwater quality data fr
Page 106 and 107: 96 7. IDENTIFICATION OF ENVIRONMENT
Page 108 and 109: 98 3. Echinoderm (Fellaster zelandi
Page 110 and 111: 100 trace metals (probably Cu and Z
Page 112 and 113: 102 concentrations of</stro
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Page 118 and 119: 108 A review of se
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Page 122 and 123: 112 grazers such as mud flat snails
Page 124 and 125: 114 8. OVERVIEW 8.1 Vehicles as sou
Page 126 and 127: 116 The quality <s
Page 130 and 131: 120 A number of st
Page 132 and 133: 122 construction. Center for Resear
Page 134 and 135: 124 Carey, J.; Cook, P.; Ciesy, J.;
Page 136 and 137: 126 Ellis, J. B. 1986: Pollutional
Page 138 and 139: 128 Harrop D. O. 1984: Stormwater r
Page 140 and 141: 130 Kennedy, P. C.; Kjellstrom, T.
Page 142 and 143: 132 Maltby, L. A.; Boxall, D. M.; F
Page 144 and 145: 134 Novotny, V.; Muehring, D.; Zito
Page 146 and 147: 136 Ruck, J. 1998: Evaluation <stro
Page 148 and 149: 138 Terracciano, S. A.; O’Brien,
Page 150 and 151: 140 Webster, J. G.; Brown, K. L.; W
Page 152: 142 10. ACKNOWLEDGEMENTS Thanks to
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The Effects of Road Transport on Freshwater and Marine Ecosystems

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