The Effects of Road Transport on Freshwater and Marine Ecosystems

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46 <strong>The</strong> material which would be deposited immediately adjacent to the road has the potential to: Deposit on stream and lake surfaces within a close distance (e.g., 100 m) <strong>of</strong> the road edge. Deposit on estuary and coastal water surfaces within a close distance <strong>of</strong> the road edge. Deposit on inter-tidal sediment surfaces in tidal creeks, embayments and coastal areas, if these environments do occur immediately adjacent to the road. Calculation <strong>of</strong> the deposition rates is important to establish the proportion <strong>of</strong> contaminants entering receiving waters by deposition compared to stormwater discharge. NIWA (1996) estimated contaminant emission and deposition rates adjacent to roadways. <strong>The</strong>se data are presented in Table 5.1. Table 5.1 - Contaminant emission and deposition rates adjacent to roadways (from NIWA 1996). Contaminant Total Emission Rate (mg/VKT) Deposition to <strong>Road</strong>way (mg/VKT) Deposition to <strong>Road</strong>side Margins (ng/m 2 /VKT) 0-5 m 0-15 m 0-30 m Lead 18 1.8 75 47 32 Zinc 4.0 0.4 17 10 7 Copper 0.16 0.16 0 0 0 Total PAH 0.25 0.015 0.63 0.4 0.27 Note: VKT = Vehicle km travelled. 5.2.4 Regional and Remote Deposition Gaseous and particulate material remaining airborne following local deposition are available for movement by local and regional climatic processes. <strong>The</strong> fate <strong>of</strong> emissions is dependent upon the chemistry <strong>of</strong> the elements and compounds involved. For example, metals associated with large particles (Fe, Mn) will be preferentially removed by dry deposition and metals associated with smaller particulates or gas phases (Sb, Hg) will travel further. <strong>The</strong>re is an exhaustive range <strong>of</strong> studies that have shown that airborne emissions from urban areas, and therefore roadways, can be transported significant distances. Most work that can be related back to motor vehicle emissions has utilised lead as a marker to track the distribution <strong>of</strong> the emissions. Examples include: Hewitt & Rashed (1990) estimated that 86% <strong>of</strong> the Pb emitted by motor vehicles was available for regional and long-range movement. Gulson et al. (1981) utilised Pb isotopes to demonstrate that contamination <strong>of</strong> soil by lead takes place up to 50 km from Adelaide. Tatsumoto & Patterson (1963) found through isotopic composition that the source <strong>of</strong> Pb in snow 800 km east <strong>of</strong> Los Angeles was lead from vehicle emissions. <strong>The</strong>re has been a very large amount <strong>of</strong> work undertaken on the distribution <strong>of</strong> Pb in the environment at a regional and at a global level. This information is widespread in the international literature. For earlier information the reader is referred to significant documents such as USEPA (1986) (Air quality criteria for lead documents). In New Zealand, Fergusson (1993), showed that the lead dustfall flux decreased westward (inland) from Christchurch with 10-12 µg/cm 2 /yr being recorded in the inner city, 6-12 µg/cm 2 /yr in outer Kingett Mitchell Ltd Resource & Environmental Consultants
47 residential areas, 3-5 µg/cm 2 /yr in rural areas and 1-2 µg/cm 2 /yr in remote rural areas and 0.1-0.3 µg/cm 2 /yr in uninhabited areas. Although Pb has been removed from petrol, the work <strong>of</strong> Fergusson served to show how far vehicle emissions travelled prior to deposition. Overall, the Fergusson (1993) assessment indicated a factor <strong>of</strong> 10 between urban and rural deposition and a factor <strong>of</strong> about 100 between urban and remote deposition in New Zealand. Since the introduction <strong>of</strong> catalytic converters to motor vehicles (into the US, Canada and Japan in 1976), PGMs have been emitted from exhausts into the environment. Analysis <strong>of</strong> ice and snow on Mt Blanc by Van de Velde et al. (2000) demonstrated that Pd and Rh concentrations are higher in the last decades compared to deeper older snow (due to a variety <strong>of</strong> sources). In a study <strong>of</strong> PGEs in Greenland snow, Barbante et al. (2001) found that in recent snows dated from 1969-1975, concentrations <strong>of</strong> Pt, Pd and Rh were already 6, 15 and 45 times higher than observed in pre industrial snow (e.g., 7,000 yrs BP). In the period 1975-1995 following the introduction <strong>of</strong> catalytic converters, the concentrations had risen to 40, 80 and 120 times higher. <strong>The</strong> presence <strong>of</strong> these elements in Greenland snow provides evidence <strong>of</strong> their tropospheric transport and dispersion in the northern hemisphere. Given the proportion <strong>of</strong> nitrogen oxide emissions attributed to motor vehicles (refer section 4), it is likely that motor vehicle emissions contribute nitrogen to fresh waters and coastal waters. It has been estimated that atmospheric nitrogen input to water bodies such as Chesapeake Bay range from 5 to 50% (about 30%). As such, vehicle-derived nitrogen oxides could potentially be an important contribution to the flux <strong>of</strong> nitrogen in coastal waters (in particular to enclosed harbours adjacent to large urban areas). Information on the local, regional and global transport <strong>of</strong> contaminants emitted by motor-vehicles has shown that emissions can be transported to locations removed from the point <strong>of</strong> origin. <strong>The</strong> distance <strong>of</strong> transport and hence deposition is related to whether the contaminant was gaseous or associated with very small particles. <strong>Transport</strong> away from the source to areas beyond busy roads and urban areas, allows contaminants to be deposited to lake surfaces, intertidal mud-flats and the sea surface. This is discussed further in following sections <strong>of</strong> this report. 5.3 Fate on the Street Surface and in the Stormwater System 5.3.1 Introduction When contaminants reach the street surface (and adjacent soils) via dry deposition and washout (rain), they undergo a variety <strong>of</strong> processes that in many cases result in significant changes to the composition, speciation and form <strong>of</strong> the contaminant. While resident on the street surface, contaminants and particulates are exposed to wind, heat and sunlight. Following rainfall and passage through the stormwater system, they are exposed to water with resultant changes in chemical equilibrium and speciation. <strong>The</strong>se processes are important as they influence toxicity, potential bioaccumulation and other interactions with the natural environment. 5.3.2 Street Surfaces Metals A variety <strong>of</strong> elements are added to street dusts in forms ranging from fine aerosol, zinc oxide in rubber, to metal particulates such as Cu, Fe, Cr, Zn, aluminium (Al) (refer Section 2). Much <strong>of</strong> the work that has been carried out on dusts has concentrated on the chemistry <strong>of</strong> Pb. Lead was emitted from motor vehicles as the mixed halide PbBrCl with minor amounts <strong>of</strong> lead oxide, sulphate, chlorides and phosphates (Habibi 1973, USEPA 1977,1986). Examination <strong>of</strong> soils and dusts has shown that lead sulphate is the dominant lead salt present. Fergusson & Simmonds (1983) found that the dominant Kingett Mitchell Ltd Resource & Environmental Consultants
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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 38 and 39: 28 Figure 4.2 - Variation in the co
Page 40 and 41: 30 Metal Cu Cd Pb Zn Table 4.6 - Su
Page 42 and 43: 32 probably reflect lower traffic d
Page 44 and 45: 34 (1995) provide a general review
Page 46 and 47: 36 Further data can be found in the
Page 48 and 49: 38 by ARC (1994) indicated that TPH
Page 50 and 51: 40 Cations/Anions Common ionic cons
Page 52 and 53: 42 Catchpits Between the street sur
Page 54 and 55: 44 5 PATHWAYS & FATE OF CONTAMINANT
Page 58 and 59: 48 crystalline species present were
Page 60 and 61: 50 Figure 5.1 - Percentage
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Page 64 and 65: 54 5.4.2 Dispersion Dilution and di
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Page 68 and 69: 58 6.2 Freshwater Ecosystems 6.2.1
Page 70 and 71: 60 General Assessment Tools Commonl
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Page 84 and 85: 74 Zinc Measurement of</str
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Page 96 and 97: 86 Although a range of</str
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
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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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