Pollutants in runoff from urban surfaces

TY - BOOK

T1 - Pollutants in runoff from urban surfaces

AU - Shajib, Md Tariqul Islam

PY - 2019

Y1 - 2019

N2 - Urbanization leads to increased impervious surfaces, which in turn alter hydrological cycles by creating an impenetrable barrier to the natural infiltration of stormwater runoff. Urban stormwater runoff carries pollutants from urban surfaces to nearby watersheds that deteriorate water quality, thus adversely affecting receiving water bodies. Total suspended solid (TSS), polycyclic aromatic hydrocarbons (PAHs) and increased heavy metal (HM) concentrations, pesticides, organotins, polychlorinated bisphenols (PCBs), volatile organic compounds, alkylphenols, phthalates, methyl tert-butyl ether, microplastic, pharmaceuticals and other personal care products are the major causes of water quality degradation in urban waterways. The HMs in stormwater runoff is important to address since they are non-biodegradable pollutants, thereby posing a threat to the environment. Another widespread group of persistent organic pollutants (POPs) are PAHs, and seven of the 16 EPA PAHs are considered carcinogenic. Main direct sources of key pollutants such as TSSs, PAHs and heavy metals in stormwater runoff comprise vehicles, vehicular parts, pavement and roofs. However, atmospherically deposited particles represent the real source of pollutants in stormwater runoff. Moreover, owing to increased utilization of rare earth element (REEs), the series of 15 lanthanide elements, mainly originated from atmospheric deposition which may source from traffic emission and coal burning activities shich show the urban fingerprint are of particular interest for monitoring the concentration levels, spatial distribution in urban runoff. Therefore, urban runoff sampling campaigns have been conducted in moderately trafficked roads (MTR), less trafficked roads (LTR), residential parking lots (RPL) and three different rooftop surfaces in this study. Additionally, an artificial rainfall simulator has been constructed and applied to measure the atmospherically derived pollutant washed-off from different urban locations such as residential rooftops, rooftops nearby traffic area and institute rooftop. Moreover, velocity dependent passive samplers have been used to obtain integrated freely dissolved metals and PAH concentrations in urban runoff. HMs, PAHs and rare earth elements have had main focus in this PhD study. This study also involved partitioning of HMs in time-dependent continuous samples, investigating their concentrations as dissolved and particulate phases, assessing the pollution status and elucidating the sources of HMs and REEs in urban runoff. Sample preparation was accomplished following standard methods for the examination of water and wastewater, and HM and REE analyses were carried out using ICP-OES and ICP-MS. The PAH analyses obtained using velocity passive sampling devices (Sorbicell VOCs) were carried out at Eurofins. Extraction, digestion and analysis for metals in velocity dependent passive samplers (Sorbicell) were carried out at the laboratory of Institute of Geographic Sciences and Natural Resources Research (IGSNRR) in Beijing, following the guidelines of the manufacturer. The HM concentrations in urban runoff varied in different urban surfaces (trafficked areas, rooftops and parking lots) and trafficked areas contributed higher amount of HM than rooftops and parking lot runoff. It was also found that the metals were mainly (> 80%) particulate bound in urban runoff in Beijing. Higher concentration (p < 0.05) of total metals was found at the beginning of a rain event and fall-off at the end for most of the HM and surfaces. By comparing the data in the scientific literature with the different environmental quality standard (EQSs), HMs concentrations in urban runoff exceeded both the Chinese standard Level III (swimming and fisheries area) as well as the European standard. In Beijing runoff, two to ten-fold higher concentrations of Cd, Mn, Zn, Al, Fe, Pb and Ni were found compared with similar studies undertaken around the world. It was however, particularly alarming that antimony (Sb) was observed at concentrations 20 times higher in runoffs in Beijing than other locations. The correlation, cluster and principal component analysis pointed to allocation of Cu, Cd, Cr, Mn, Ni, Pb and Zn to the same source which was vehicular activities. Together with vehicular emission sources, Mn and Zn were also originated from atmospheric particulates in Beijing and surrounding provinces. This study on rare earth elements in urban runoff documented that trafficked areas runoff contained higher (43.2μg/l) ΣREEs than the runoff from roofs (26.3μg/l) and residential parking lot areas (7.65μg/l). Total concentrations of ΣREEs and dissolved fractions were 3-14 times and 1.5-6 times higher in all samples, respectively, than internationally published data. The La, Ce and Pr were found higher than other REEs revealed that the REEs in Beijing urban runoff are LREE-enriched. The La/Sm and Ce/Yb ratios together with cluster analysis, correlations and principal component analysis for Beijing´s urban runoff showed that REEs in Beijing runoff samples are originated from the atmospheric deposition which may result from coal burning and traffic emissions in Beijing. Higher Ce concentrations (5 -28 times) were found in Beijing runoff than the reference rain samples (the rain samples collected in acid washed clean bottles) which indicated that the urban runoff samples were heavily contaminated by anthropogenic activities mainly from vehicular contributions. The ratio of La/Sm (5.90 – 8.05), La/Ce (0.53 – 0.58) and Ce/Yb (31.0 42.7) ratios also pointed to REE sources from traffic emissions and coal burning which can be employed as urban fingerprint. The impact of the antecedent dry days (ADD) in between two rain events on pollutant loading has been compiled and the result showed that average atmospheric Pb, Zn, Cu, Cr, Cd, Mn, Sb and Ni deposition are 7.75, 34.5, 3.86, 4.78, 0.09, 19.3, 19.6 and 2.43 mg m-2 yr-1 in Beijing urban area, respectively, which were many folds higher than the atmospheric deposition in other cities. It was also observed that the rooftops nearby moderately traffic road exhibited higher atmospheric metal deposition than residential rooftops and institute rooftops. Moreover, it was estimated in Beijing that an urban surface of one m2 could contribute 2.5 g of Al and 2.18 g of Fe per year to urban runoff which is 18 – 27 times higher than the Al and Fe flux of bigger cities in Australia and Japan. In urban runoff studies, a new velocity dependent passive sampling technique may be used for monitoring pollutants of interest over longer periods of time instead of focusing on single events. Results revealed that dissolved concentrations of Cu (52.5 ± 10.6 μg/l), Zn (37.5 ± 8.5 μg/l) and Mn (48.5 ± 9.2 μg/l) estimated by the passive samplers were higher than the Cu, Zn and Mn concentrations collected manually during the same period of time. Finally, the information gleaned from this study contributes to the available data on pollutants in urban runoff. It may also provide reference data for assessing potential environmental risks and designing the most optimal management control of stormwater runoff pollution.

AB - Urbanization leads to increased impervious surfaces, which in turn alter hydrological cycles by creating an impenetrable barrier to the natural infiltration of stormwater runoff. Urban stormwater runoff carries pollutants from urban surfaces to nearby watersheds that deteriorate water quality, thus adversely affecting receiving water bodies. Total suspended solid (TSS), polycyclic aromatic hydrocarbons (PAHs) and increased heavy metal (HM) concentrations, pesticides, organotins, polychlorinated bisphenols (PCBs), volatile organic compounds, alkylphenols, phthalates, methyl tert-butyl ether, microplastic, pharmaceuticals and other personal care products are the major causes of water quality degradation in urban waterways. The HMs in stormwater runoff is important to address since they are non-biodegradable pollutants, thereby posing a threat to the environment. Another widespread group of persistent organic pollutants (POPs) are PAHs, and seven of the 16 EPA PAHs are considered carcinogenic. Main direct sources of key pollutants such as TSSs, PAHs and heavy metals in stormwater runoff comprise vehicles, vehicular parts, pavement and roofs. However, atmospherically deposited particles represent the real source of pollutants in stormwater runoff. Moreover, owing to increased utilization of rare earth element (REEs), the series of 15 lanthanide elements, mainly originated from atmospheric deposition which may source from traffic emission and coal burning activities shich show the urban fingerprint are of particular interest for monitoring the concentration levels, spatial distribution in urban runoff. Therefore, urban runoff sampling campaigns have been conducted in moderately trafficked roads (MTR), less trafficked roads (LTR), residential parking lots (RPL) and three different rooftop surfaces in this study. Additionally, an artificial rainfall simulator has been constructed and applied to measure the atmospherically derived pollutant washed-off from different urban locations such as residential rooftops, rooftops nearby traffic area and institute rooftop. Moreover, velocity dependent passive samplers have been used to obtain integrated freely dissolved metals and PAH concentrations in urban runoff. HMs, PAHs and rare earth elements have had main focus in this PhD study. This study also involved partitioning of HMs in time-dependent continuous samples, investigating their concentrations as dissolved and particulate phases, assessing the pollution status and elucidating the sources of HMs and REEs in urban runoff. Sample preparation was accomplished following standard methods for the examination of water and wastewater, and HM and REE analyses were carried out using ICP-OES and ICP-MS. The PAH analyses obtained using velocity passive sampling devices (Sorbicell VOCs) were carried out at Eurofins. Extraction, digestion and analysis for metals in velocity dependent passive samplers (Sorbicell) were carried out at the laboratory of Institute of Geographic Sciences and Natural Resources Research (IGSNRR) in Beijing, following the guidelines of the manufacturer. The HM concentrations in urban runoff varied in different urban surfaces (trafficked areas, rooftops and parking lots) and trafficked areas contributed higher amount of HM than rooftops and parking lot runoff. It was also found that the metals were mainly (> 80%) particulate bound in urban runoff in Beijing. Higher concentration (p < 0.05) of total metals was found at the beginning of a rain event and fall-off at the end for most of the HM and surfaces. By comparing the data in the scientific literature with the different environmental quality standard (EQSs), HMs concentrations in urban runoff exceeded both the Chinese standard Level III (swimming and fisheries area) as well as the European standard. In Beijing runoff, two to ten-fold higher concentrations of Cd, Mn, Zn, Al, Fe, Pb and Ni were found compared with similar studies undertaken around the world. It was however, particularly alarming that antimony (Sb) was observed at concentrations 20 times higher in runoffs in Beijing than other locations. The correlation, cluster and principal component analysis pointed to allocation of Cu, Cd, Cr, Mn, Ni, Pb and Zn to the same source which was vehicular activities. Together with vehicular emission sources, Mn and Zn were also originated from atmospheric particulates in Beijing and surrounding provinces. This study on rare earth elements in urban runoff documented that trafficked areas runoff contained higher (43.2μg/l) ΣREEs than the runoff from roofs (26.3μg/l) and residential parking lot areas (7.65μg/l). Total concentrations of ΣREEs and dissolved fractions were 3-14 times and 1.5-6 times higher in all samples, respectively, than internationally published data. The La, Ce and Pr were found higher than other REEs revealed that the REEs in Beijing urban runoff are LREE-enriched. The La/Sm and Ce/Yb ratios together with cluster analysis, correlations and principal component analysis for Beijing´s urban runoff showed that REEs in Beijing runoff samples are originated from the atmospheric deposition which may result from coal burning and traffic emissions in Beijing. Higher Ce concentrations (5 -28 times) were found in Beijing runoff than the reference rain samples (the rain samples collected in acid washed clean bottles) which indicated that the urban runoff samples were heavily contaminated by anthropogenic activities mainly from vehicular contributions. The ratio of La/Sm (5.90 – 8.05), La/Ce (0.53 – 0.58) and Ce/Yb (31.0 42.7) ratios also pointed to REE sources from traffic emissions and coal burning which can be employed as urban fingerprint. The impact of the antecedent dry days (ADD) in between two rain events on pollutant loading has been compiled and the result showed that average atmospheric Pb, Zn, Cu, Cr, Cd, Mn, Sb and Ni deposition are 7.75, 34.5, 3.86, 4.78, 0.09, 19.3, 19.6 and 2.43 mg m-2 yr-1 in Beijing urban area, respectively, which were many folds higher than the atmospheric deposition in other cities. It was also observed that the rooftops nearby moderately traffic road exhibited higher atmospheric metal deposition than residential rooftops and institute rooftops. Moreover, it was estimated in Beijing that an urban surface of one m2 could contribute 2.5 g of Al and 2.18 g of Fe per year to urban runoff which is 18 – 27 times higher than the Al and Fe flux of bigger cities in Australia and Japan. In urban runoff studies, a new velocity dependent passive sampling technique may be used for monitoring pollutants of interest over longer periods of time instead of focusing on single events. Results revealed that dissolved concentrations of Cu (52.5 ± 10.6 μg/l), Zn (37.5 ± 8.5 μg/l) and Mn (48.5 ± 9.2 μg/l) estimated by the passive samplers were higher than the Cu, Zn and Mn concentrations collected manually during the same period of time. Finally, the information gleaned from this study contributes to the available data on pollutants in urban runoff. It may also provide reference data for assessing potential environmental risks and designing the most optimal management control of stormwater runoff pollution.

M3 - Ph.D. thesis

BT - Pollutants in runoff from urban surfaces

PB - Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen

ER -