The Effects of Road Transport on Freshwater and Marine Ecosystems

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20 to elevated concentrations in tyres and the re-introduction <strong>of</strong> Pb to the road surface from areas beside roads where the concentration is elevated (principally because <strong>of</strong> historic road side deposition from vehicle exhaust emissions). <strong>The</strong> particulates on road surfaces in New Zealand also contain elevated concentrations <strong>of</strong> the elements Cd, Cr, Mo, Ni, and Sb. <strong>The</strong>se are sources principally from tyres and brake pads. It is likely that the Sb and Mo are contributed by specific commercial types <strong>of</strong> brake pads. A proportion <strong>of</strong> the New Zealand vehicle fleet uses catalytic converters. As a result the PGEs (Pt, Rh, Pd) will be emitted to the road environment from the exhaust system. International data shows that there are low concentrations <strong>of</strong> PGEs on road surfaces. <strong>The</strong>re is no data on the distribution <strong>of</strong> PGEs in the road environment in New Zealand. <strong>The</strong>re is limited information on the nature <strong>of</strong> organic compounds within the road surface environment. Most data that has been collected to characterise organic compounds in the road environment has been on PAHs. Analysis <strong>of</strong> PAHs in road surface particles in New Zealand has shown that particles on road surfaces have elevated concentrations <strong>of</strong> a range <strong>of</strong> PAHs. Based on overseas information, there will be a range <strong>of</strong> substituted PAHs attached to particles on the road surface. Estimating the proportion <strong>of</strong> contaminants in stormwater derived from motor-vehicles is complex as it requires either an accurate estimate <strong>of</strong> the amount <strong>of</strong> contaminant emitted from vehicles or an estimate <strong>of</strong> the amount <strong>of</strong> contaminant produced by other sources. <strong>The</strong>re have been a number <strong>of</strong> estimates made <strong>of</strong> the proportion <strong>of</strong> contaminants in stormwater generated within urban areas that is emitted by motor-vehicles. Previous estimates have tended to over-estimate the amount <strong>of</strong> contaminant contributed by vehicles as the estimates were based on only on calculated vehicle emission rates and general information on total stormwater loads. Specific work undertaken in Auckland City is allowing some refinement <strong>of</strong> that estimate in New Zealand. <strong>The</strong> current best estimates identify the 50%ile road contribution for Cu and Zn as 17 and 16% respectively. <strong>The</strong>re are still substantial uncertainties associated with these estimates and they will need continued refinement as new data becomes available. Kingett Mitchell Ltd Resource & Environmental Consultants
21 4. STORMWATER RUNOFF 4.1 Introduction As identified in the previous section, the interpretation <strong>of</strong> the influence <strong>of</strong> motor vehicles on urban stormwater quality is complicated by the influence <strong>of</strong> other adjacent urban activities. In both general urban stormwater and specific road and motorway run<strong>of</strong>f, deposition <strong>of</strong> particulate matter from the atmosphere will contribute material not entirely derived from motor vehicle emissions. <strong>The</strong> chemistry <strong>of</strong> stormwater is influenced by the chemistry <strong>of</strong> the sediments washed from roads by stormwater and by aspects <strong>of</strong> the stormwater system including catchpit water chemistry. A considerable amount <strong>of</strong> data has been collected on stormwater quality particularly in the United States and the United Kingdom. In the US programmes such as the National Urban Run<strong>of</strong>f Programme (NURP), have collected an extensive amount <strong>of</strong> specific highway data and general urban run<strong>of</strong>f data. In the following sections an overview <strong>of</strong> stormwater quality is provided in relation to the key constituents <strong>of</strong> stormwater. Stormwater constituents chemistry concentrations are expressed typically as g/m 3 or mg/L. Stormwater chemistry is also reported as load or mass/day per unit <strong>of</strong> contributing stormwater catchment (e.g., kg/day). <strong>The</strong> event-mean concentration (EMC) is commonly used to describe the concentration <strong>of</strong> constituents in storm events. <strong>The</strong> EMC is defined as the total mass discharged during the event divided by the total volume <strong>of</strong> stormwater discharged during the event. <strong>The</strong> EMC is therefore a flow weighted average <strong>of</strong> the constituent concentration. <strong>The</strong>re are several matters that should be taken into account when comparing stormwater data from different sources. 1. <strong>The</strong> stormwater may be influenced to an unknown extent by <strong>of</strong>f-site non-road related activities. 2. <strong>The</strong> data may vary from single grab samples to means <strong>of</strong> grab samples to EMCs and means <strong>of</strong> EMCs. 3. <strong>The</strong> stormwater quality will vary depending upon whether the sample was taken from a kerb and channel and piped stormwater system compared to stormwater that has passed overland before it was sampled (e.g., from motorways with no curb and channel). 4.2 Particulates in Urban Run<strong>of</strong>f and Motorway Run<strong>of</strong>f Rainfall will transport particulate and dissolved material on roadway surfaces via the stormwater system to adjacent treatment systems or a receiving environment. Material transported from the street surface and road gutters <strong>of</strong> urban areas will contain a range <strong>of</strong> contaminants with some sourced from nontransport related activities. <strong>The</strong> particulate matter transported from highways, bridges and rural roads will more closely reflect the nature <strong>of</strong> the road surface and emissions from motor vehicles than general urban roads subject to contributions from other sources. Suspended Solids Williamson (1993) provides a review <strong>of</strong> the concentration <strong>of</strong> suspended solids in urban stormwater. ARWB (1988) also provides an overview <strong>of</strong> data on suspended sediment in urban run<strong>of</strong>f. Williamson (1993) identified a median event mean concentration <strong>of</strong> 170 g/m 3 for the stormwater data reviewed. Table 4.1 provides a summary <strong>of</strong> the Williamson (1993) data and some examples <strong>of</strong> recent motorway run<strong>of</strong>f data including ARC unpublished data on the S.H.-1 motorway at Otahuhu in Auckland. Data is also presented for a number <strong>of</strong> US motorway studies. Urban run<strong>of</strong>f data shows a high degree <strong>of</strong> variability as does motorway run<strong>of</strong>f. <strong>The</strong> variability amongst the urban run<strong>of</strong>f data and the motorway data is not surprising given the large number <strong>of</strong> factors influencing particle sources and contributions <strong>of</strong> particles to the road surface. <strong>The</strong> median <strong>of</strong> the Kingett Mitchell Ltd Resource & Environmental Consultants
Page 1: The Effect
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Page 8 and 9: iv 7. IDENTIFICATION OF ENVIRONMENT
Page 10 and 11: vi MW Molecular weight N Nitrogen N
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Page 14 and 15: 4 Table 2.1 - Contaminant Source Cl
Page 16 and 17: 6 mg/kg) and Zn (25-34,500 mg/kg).
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Page 28 and 29: 18 Yang et al. (1999) examined the
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Page 54 and 55: 44 5 PATHWAYS & FATE OF CONTAMINANT
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70 deposition, tracking of<
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72 one factor used to classify orga
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74 Zinc Measurement of</str
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76 in stormwater and receiving wate
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78 minute; sub-mitochondrial partic
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80 Toxicity tests have undertaken u
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82 High molecular weight PAHs are t
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84 Note: Sources refer Table 5.2. F
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86 Although a range of</str
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88 Bioaccumulation can be assessed
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90 Figure 6.2 - metal concentration
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92 6.5.3 Bioaccumulation of
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94 Water Stormwater quality data fr
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96 7. IDENTIFICATION OF ENVIRONMENT
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98 3. Echinoderm (Fellaster zelandi
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100 trace metals (probably Cu and Z
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102 concentrations of</stro
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104 that “concentrations
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106 A large amount of</stro
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108 A review of se
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110 Samples of man
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112 grazers such as mud flat snails
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114 8. OVERVIEW 8.1 Vehicles as sou
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116 The quality <s
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118 International studies have show
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120 A number of st
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122 construction. Center for Resear
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124 Carey, J.; Cook, P.; Ciesy, J.;
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126 Ellis, J. B. 1986: Pollutional
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128 Harrop D. O. 1984: Stormwater r
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130 Kennedy, P. C.; Kjellstrom, T.
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132 Maltby, L. A.; Boxall, D. M.; F
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134 Novotny, V.; Muehring, D.; Zito
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136 Ruck, J. 1998: Evaluation <stro
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138 Terracciano, S. A.; O’Brien,
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140 Webster, J. G.; Brown, K. L.; W
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142 10. ACKNOWLEDGEMENTS Thanks to
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