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Nordqvist, Kerstin
Publications (10 of 12) Show all publications
Müller, A., Österlund, H., Nordqvist, K., Marsalek, J. & Viklander, M. (2019). Building surface materials as sources of micropollutants in building runoff: A pilot study. Science of the Total Environment, 680, 190-197
Open this publication in new window or tab >>Building surface materials as sources of micropollutants in building runoff: A pilot study
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2019 (English)In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 680, p. 190-197Article in journal (Refereed) Published
Abstract [en]

Control of diffuse pollution is critical for achieving good surface water quality status. In this context, pollutant contributions from building materials have received increased attention in recent decades. This study examined the releases of metals, nonylphenols and phthalates from ten common building surface materials (installed in triplicates) into rainwater runoff from six rain events. The highest releases of metals were from copper and zinc sheets (average concentrations of 3090 μg/L Cu and 7770 μg/L Zn respectively), while other metal materials, e.g., Corten weathering steel, exhibited lower releases. PVC roofing released high concentrations of nonylphenols and phthalates (average concentrations of up to 26 μg/L nonylphenols and 455 μg/L Diisononyl phthalate, DINP) which have not been investigated in the earlier studies. Pollutant releases varied between events, likely because of weather conditions and rainfall characteristics. Study findings should be valuable for environmentally responsible applications of the existing building materials and the development of new ones, as well as the investigations and risk assessment of specific pollutants in stormwater.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Building surface materials, Diffuse pollution sources, Metals, Nonylphenols, Phthalates, Stormwater quality
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-73883 (URN)10.1016/j.scitotenv.2019.05.088 (DOI)000468863400019 ()31108449 (PubMedID)2-s2.0-85065712456 (Scopus ID)
Funder
Swedish Research Council Formas, 942 – 2016-73Vinnova, 2016-05176
Note

Validerad;2019;Nivå 2;2019-06-05 (oliekm)

Available from: 2019-05-09 Created: 2019-05-09 Last updated: 2019-09-18Bibliographically approved
Nyström, F., Nordqvist, K., Herrmann, I., Hedström, A. & Viklander, M. (2017). Removal of small particles from urban snow melt mixture by coagulation/flocculation and sedimentation. In: 14th IWA/IAHR International Conference on Urban Drainage: Conference Proceedings, 2017. Paper presented at 14th IWA/IAHR International Conference on Urban Drainage, ICUD 2017, Prague, September 10-15 2017.
Open this publication in new window or tab >>Removal of small particles from urban snow melt mixture by coagulation/flocculation and sedimentation
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2017 (English)In: 14th IWA/IAHR International Conference on Urban Drainage: Conference Proceedings, 2017, 2017Conference paper, Oral presentation with published abstract (Other academic)
Abstract [en]

This abstract presents a laboratory study of a coagulation/flocculation process on an urban snow melt mixture. Coagulation/flocculation is ubiquitous in water treatment, but has seen little use in the stormwater context. Using a jar-test procedure five different chemicals are evaluated as primary coagulants and their treatment performance on urban snow melt with respect to solids removal and metal content. Particle-size distribution measurements will indicate the process effect on different size fractions in the urban snow melt. Analysis for metal content will show the extent of metal reduction that occurs, either by separating out the particulate fraction or due to precipitation reactions.

National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-66522 (URN)
Conference
14th IWA/IAHR International Conference on Urban Drainage, ICUD 2017, Prague, September 10-15 2017
Available from: 2017-11-09 Created: 2017-11-09 Last updated: 2017-11-24Bibliographically approved
Nyström, F., Nordqvist, K., Herrmann, I., Hedström, A. & Viklander, M. (2016). Flocculation and membrane filtration of stormwater: laboratory experiments (ed.). Paper presented at IWA Conference for the Specialist Group on Particle Separation : Advances in particle science and separation: meeting tomorrow’s challenges 22/06/2016 - 24/06/2016. Paper presented at IWA Conference for the Specialist Group on Particle Separation : Advances in particle science and separation: meeting tomorrow’s challenges 22/06/2016 - 24/06/2016.
Open this publication in new window or tab >>Flocculation and membrane filtration of stormwater: laboratory experiments
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2016 (English)Conference paper, Oral presentation only (Other academic)
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-34739 (URN)90498099-3cbd-4608-a219-4d9fb839506b (Local ID)90498099-3cbd-4608-a219-4d9fb839506b (Archive number)90498099-3cbd-4608-a219-4d9fb839506b (OAI)
Conference
IWA Conference for the Specialist Group on Particle Separation : Advances in particle science and separation: meeting tomorrow’s challenges 22/06/2016 - 24/06/2016
Note
Godkänd; 2016; 20160617 (frenys)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Galfi, H., Haapala, J., Nordqvist, K., Westerlund, C., Blecken, G.-T., Marsalek, J. & Viklander, M. (2016). Inter-Event and Intra-Event Variations of Indicator Bacteria Concentrations in the Storm Sewer System of the City of Östersund, Sweden (ed.). Paper presented at . Journal of environmental engineering, 142(7), Article ID 6016003.
Open this publication in new window or tab >>Inter-Event and Intra-Event Variations of Indicator Bacteria Concentrations in the Storm Sewer System of the City of Östersund, Sweden
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2016 (English)In: Journal of environmental engineering, ISSN 0733-9372, E-ISSN 1943-7870, Vol. 142, no 7, article id 6016003Article in journal (Refereed) Published
Abstract [en]

An episode of microbiological contamination of the drinking water supply of the City of Östersund, Sweden (63°10′45″N; 14°38′09″E) prompted a study of fecal pollution in four storm drainage catchments discharging in the vicinity of the water treatment plant intake, with the overall aim of determining the presence and variation of standard fecal indicator bacteria strains and total suspended solids (TSS) in stormwater from urban catchments with specific land uses and sizes varying from 5 to 40 ha. Four bacteria strains used as indicators of fecal pollution in Sweden were studied: total coliforms, enterococci, Escherichia coli (E. coli) and Clostridium perfringens (C. perfringens). In dry weather, indicator bacteria concentrations in storm sewers conveying baseflow did not exceed 100  colony forming units (CFU)/100  mL 100  colony forming units (CFU)/100  mL, but during wet weather, total coliform and enterococci concentrations increased 10 2 102 to 10 3 103 times, compared to those in baseflow, and considerably less in the case of E. coli and C. perfringens. Bacteria concentrations differed significantly among the sampling sites and in the majority of events observed in the four catchments; higher bacteria concentrations were observed during the early phases of runoff. Only in one catchment, positive correlations were observed between TSS and total coliforms, E. coli, and enterococci, suggesting similar sources; in the remaining catchments, no such correlations were observed. The collected indicator bacteria data represent a useful addition to the available data on indicator bacteria in stormwater in cold-climate regions.

National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-3789 (URN)10.1061/(ASCE)EE.1943-7870.0001067 (DOI)000378859100002 ()2-s2.0-84975230403 (Scopus ID)19f235bd-4a41-45ea-8474-5bc0ae5d1900 (Local ID)19f235bd-4a41-45ea-8474-5bc0ae5d1900 (Archive number)19f235bd-4a41-45ea-8474-5bc0ae5d1900 (OAI)
Note
Validerad; 2016; Nivå 2; 20160223 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Galfi, H., Nordqvist, K., Sundelin, M., Blecken, G.-T., Marsalek, J. & Viklander, M. (2014). Comparison of indicator bacteria concentrations obtained by automated and manual sampling of urban stormwater runoff (ed.). Paper presented at . Water, Air and Soil Pollution, 225(9), Article ID 2065.
Open this publication in new window or tab >>Comparison of indicator bacteria concentrations obtained by automated and manual sampling of urban stormwater runoff
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2014 (English)In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 225, no 9, article id 2065Article in journal (Refereed) Published
Abstract [en]

A comparative study of indicator bacteria concentrations obtained by laboratory analysis of grab samples of storm water, which were collected manually or by automatic samplers, was carried out in two urban catchments. Samples were analyzed for four types of indicator bacteria, total coliforms, Escherichia coli (E. coli), enterococci, and Clostridium perfringens and further documented by measurements of total suspended solids (TSS) and turbidity. Analysis of complete data sets (N=198) indicated no statistically significant differences in the geometric means of all the constituent samples collected automatically or manually, but there were some small differences between the results produced by the two sampling methods applied. Total coliform concentrations were positively biased in samples collected by automatic samplers, but for the three remaining indicator bacteria (E. coli, enterococci, and C. perfringens), the opposite was true. Risk of sample cross-contamination in automatic samplers was assessed in the laboratory by sampling consecutively synthetic storm water with high and low concentrations of E. coli and enterococci. The first low-concentration samples preceded by high-concentration samples were cross-contaminated and the measured concentrations were positively biased. This cross-contamination was explained by storm-water residue in the sampling line. Such a residue remained in place even after line purging by compressed air, and its mass depended on the sampling line length (tested up to 5 m), as verified by measurements in the laboratory. The study findings should be helpful for improving field protocols for indicator bacteria sampling.

Keywords
stormwater quality, indicator bacteria, Automatic sampling, manual sampling, cross-contamination, sampling error, Chemistry - Environmental chemistry, Kemi - Miljökemi
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-3898 (URN)10.1007/s11270-014-2065-z (DOI)000341836700002 ()2-s2.0-84905517557 (Scopus ID)1befd991-d3b5-4a8c-8c7b-6a0a93a967e0 (Local ID)1befd991-d3b5-4a8c-8c7b-6a0a93a967e0 (Archive number)1befd991-d3b5-4a8c-8c7b-6a0a93a967e0 (OAI)
Note
Validerad; 2014; 20140623 (helgal)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Herrmann, I., Nordqvist, K., Hedström, A. & Viklander, M. (2014). Effect of temperature on the performance of laboratory-scale phosphorus-removing filter beds in on-site wastewater treatment (ed.). Paper presented at . Chemosphere, 117, 360-366
Open this publication in new window or tab >>Effect of temperature on the performance of laboratory-scale phosphorus-removing filter beds in on-site wastewater treatment
2014 (English)In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 117, p. 360-366Article in journal (Refereed) Published
Abstract [en]

P-sorbing filter beds appear to be viable options for treating wastewater to reduce P discharges and recover this non-renewable resource. However, greater knowledge of filters’ responses to temperature variations is required to assess their likely performance in full-scale applications and facilitate the transfer of laboratory results to the field. Thus, in the present study two filter materials (Top16 and Polonite) were characterized physicochemically and effects of temperature on their performance were investigated under controlled laboratory conditions. Using a 22 factorial design and secondary wastewater eight filter columns were tested at temperatures of 4.3 °C and 16.5 °C. Temperature significantly (α = 0.05) and strongly affected the P binding capacity of both materials, as it was 1.2- and 1.5-fold higher at 16.5 °C than at 4.3 °C for Top16 and Polonite, respectively. This is probably due to the enhanced precipitation of calcium phosphates at higher temperature. Observed reductions in total organic carbon content in the wastewater were also positively correlated with temperature, while the pH and reduction of dissolved organic carbon remained unaffected. The physicochemical analyses indicated that several calcium phases dissolved from the filter materials, primarily gypsum and bassanite from Top16 and Portlandite from Polonite. No clear evidence of any crystalline calcium phosphates was observed in the used materials. The results clearly show that temperature strongly influences the retention of P in filters and its effects should be carefully considered before using candidate filters in full-scale applications.

National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-5043 (URN)10.1016/j.chemosphere.2014.07.069 (DOI)000347263300051 ()25155452 (PubMedID)2-s2.0-84911391747 (Scopus ID)310091f1-3e81-48b6-9bbc-1818e8d70c11 (Local ID)310091f1-3e81-48b6-9bbc-1818e8d70c11 (Archive number)310091f1-3e81-48b6-9bbc-1818e8d70c11 (OAI)
Note
Validerad; 2014; 20140826 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Nordqvist, K., Galfi, H., Österlund, H., Marsalek, J., Westerlund, C. & Viklander, M. (2014). Measuring solid concentrations in urban stormwater and snowmelt: a new operational procedure (ed.). Paper presented at . Environmental Science: Processes & Impacts, 16(9), 2172-2183
Open this publication in new window or tab >>Measuring solid concentrations in urban stormwater and snowmelt: a new operational procedure
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2014 (English)In: Environmental Science: Processes & Impacts, ISSN 2050-7887, E-ISSN 2050-7895, Vol. 16, no 9, p. 2172-2183Article in journal (Refereed) Published
Abstract [en]

A comparative study of five methods measuring suspended sediment or solid concentrations in water–sediment mixtures indicated that, depending on the method used, broadly varying results can be obtained. For water–sediment mixtures containing sand size particles, the standard TSS method produced negatively biased results, accounting for 0 to 90% of the present solids; the negative bias directly depended on the magnitude of the sand fraction in the water–sediment mixture. The main reason for the differences between the TSS and the rest of the methods laid in the handling of samples; in the former methods, whole samples were analysed, whereas the TSS analysis was performed on sub-samples withdrawn from the water sample, the withdrawal process tending to exclude large particles. The methods using whole water–solid samples, rather than aliquots withdrawn from such samples, produced accurate estimates of solid concentrations, with a fairly good precision. Two whole-sample methods were studied in detail, a slightly modified standard SSC-B method and the newly proposed operational procedure referred to as the Multiple Filter Procedure (MFP), using three filters arranged in a series with decreasing pore sizes (25, 1.6 and 0.45 µm). Both methods assessed accurately concentrations of solids in a broad range of concentrations (200–8000 mg L−1) and particle sizes (0.063–4.0 mm). The newly introduced MFP was in good agreement with the SSC procedure, the differences between the two procedures not exceeding the standard bias defined for the SSC-B method. The precision of both SSC and MFP was generally better than ±10%. Consequently, these methods should be used when the total mass of transported solids is of interest.

Abstract [en]

A comparative study of five methods measuring suspended sediment or solid concentrations in water–sediment mixtures indicated that, depending on the method used, broadly varying results can be obtained. For water–sediment mixtures containing sand size particles, the standard TSS method produced negatively biased results, accounting for 0 to 90% of the present solids; the negative bias directly depended on the magnitude of the sand fraction in the water–sediment mixture. The main reason for the differences between the TSS and the rest of the methods laid in the handling of samples; in the former methods, whole samples were analysed, whereas the TSS analysis was performed on subsamples withdrawn from the water sample, the withdrawal process tending to exclude large particles. The methods using whole water–solid samples, rather than aliquots withdrawn from such samples, produced accurate estimates of solid concentrations, with a fairly good precision. Two whole-samplemethods were studied in detail, a slightly modified standard SSC-B method and the newly proposed operational procedure referred to as the Multiple Filter Procedure (MFP), using three filters arranged in a series with decreasing pore sizes (25, 1.6 and 0.45 mm). Both methods assessed accurately concentrations of solids in a broad range of concentrations (200–8000 mg L1) and particle sizes(0.063–4.0 mm). The newly introduced MFP was in good agreement with the SSC procedure, the differences between the two procedures not exceeding the standard bias defined for the SSC-B method. The precision of both SSC and MFP was generally better than 10%. Consequently, these methods should be used when the total mass of transported solids is of interest.

National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-6186 (URN)10.1039/c4em00204k (DOI)000341016000013 ()24979688 (PubMedID)2-s2.0-84906572611 (Scopus ID)462aa955-7990-4c2b-bb08-aea6171ab12b (Local ID)462aa955-7990-4c2b-bb08-aea6171ab12b (Archive number)462aa955-7990-4c2b-bb08-aea6171ab12b (OAI)
Note
Validerad; 2014; 20140623 (kernor)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Galfi, H., Haapala, J., Nordqvist, K., Westerlund, C., Blecken, G.-T., Marsalek, J. & Viklander, M. (2013). Indicator bacteria variation in separate sewer systems in Östersund, Sweden: Preliminary results (ed.). Paper presented at Novatech 2013 : International Conference on Planning and Technologies for Sustainable Urban Water Management 23/06/2013 - 26/06/2013. Paper presented at Novatech 2013 : International Conference on Planning and Technologies for Sustainable Urban Water Management 23/06/2013 - 26/06/2013.
Open this publication in new window or tab >>Indicator bacteria variation in separate sewer systems in Östersund, Sweden: Preliminary results
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2013 (English)Conference paper, Oral presentation only (Refereed)
Abstract [en]

Faecal bacteria are a major pollution threat of water bodies designated for multipurpose use including drinking water sources or recreational purposes. Even though stormwater discharges may contribute significantly to microbiological pollution, they have not been fully investigated in the European context. We have studied the presence of indicator bacteria and total suspended solids (TSS) in stormwater discharged from four urban catchments, with areas between 5 and 40 ha, in Östersund, Sweden. The aim was to determine local variation of standard bacteria strains and TSS in Swedish urban catchments with specific land uses. Further, intra event variations were investigated. During dry weather, indicator bacteria concentrations in sewers conveying baseflow did not exceed 100 CFU/100 mL. During storm runoff, total coliform and int. enterococci concentrations increased 102 to 103 times, compared to those in baseflow. Compared to these two parameters, considerably lower concentrations were observed for E. coli and C. perfringens. Bacteria concentrations differed significantly among the sampling sites and partly, a first flush phenomenon was observed. Partly, significant correlations between TSS and indicator bacteria were observed. These were catchment specific and need a more detailed assessment. Further research will focus on seasonal variations and influential factors.

Keywords
indicator bacteria, local variation, separate sewer, stormwater quality, TSS, Civil engineering and architecture - Water engineering, Samhällsbyggnadsteknik och arkitektur - Vattenteknik
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-37578 (URN)ba524871-d82e-4262-9044-6de1c15d02b3 (Local ID)ba524871-d82e-4262-9044-6de1c15d02b3 (Archive number)ba524871-d82e-4262-9044-6de1c15d02b3 (OAI)
Conference
Novatech 2013 : International Conference on Planning and Technologies for Sustainable Urban Water Management 23/06/2013 - 26/06/2013
Note
Godkänd; 2013; 20130821 (helgal)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2018-02-26Bibliographically approved
Galfi, H., Nordqvist, K., Blecken, G.-T., Viklander, M. & Marsalek, J. (2013). Influence of sampling methods on the measurements of urban stormwater quality constituents: Preliminary results (ed.). Paper presented at Novatech 2013 : International Conference on Planning and Technologies for Sustainable Urban Water Management 23/06/2013 - 26/06/2013. Paper presented at Novatech 2013 : International Conference on Planning and Technologies for Sustainable Urban Water Management 23/06/2013 - 26/06/2013.
Open this publication in new window or tab >>Influence of sampling methods on the measurements of urban stormwater quality constituents: Preliminary results
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2013 (English)Conference paper, Oral presentation only (Refereed)
Abstract [en]

The choice between automatic and manual sampling of urban stormwater quality has been addressed in the past as an issue of economic efficiency, field safety, and practicality. Nevertheless, there is experimental evidence that both types of sampling may yield statistically different stormwater quality data. While the past attention focused on differences in sampled solids, a new issue was addressed in this study, the potential impacts of sampling methods on concentrations of indicator bacteria. Towards this end, four indicator bacteria (coliforms, E. coli, enterococci and C. perfringens) were sampled in storm sewers of two urban catchments in Östersund, Sweden, using both automatic samplers and manual sampling. Such data were further supplemented by measurements of total suspended solids (TSS) and turbidity, recognizing that bacteria are mostly transported in the attachment to solids. Preliminary results indicate that there may be large differences between indicator bacteria in automatic and manual samples, with E. coli measurements yielding the least differences, and turbidity readings were correlated well with all the indicator bacteria and particularly E. coli. These findings will be used in the continuation of this study for refining the existing experimental design and developing practical guidance for surveys of municipal storm sewers for faecal pollution.

Keywords
Automatic sampling, indicator bacteria, manual sampling, stormwater quality, TSS, turbidity, Civil engineering and architecture - Water engineering, Samhällsbyggnadsteknik och arkitektur - Vattenteknik
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-39318 (URN)e01981e8-ef11-458d-823a-1c8d5ee18975 (Local ID)e01981e8-ef11-458d-823a-1c8d5ee18975 (Archive number)e01981e8-ef11-458d-823a-1c8d5ee18975 (OAI)
Conference
Novatech 2013 : International Conference on Planning and Technologies for Sustainable Urban Water Management 23/06/2013 - 26/06/2013
Note
Godkänd; 2013; 20130821 (helgal)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2018-02-26Bibliographically approved
Nordqvist, K., Viklander, M., Westerlund, C. & Marsalek, J. (2011). Measuring solids concentrations in urban runoff: methods of analysis (ed.). Paper presented at International Conference on Urban Drainage : 11/09/2011 - 15/09/2011. Paper presented at International Conference on Urban Drainage : 11/09/2011 - 15/09/2011.
Open this publication in new window or tab >>Measuring solids concentrations in urban runoff: methods of analysis
2011 (English)Conference paper, Oral presentation only (Refereed)
Abstract [en]

Various types of solids conveyed with rainfall and snowmelt runoff into receiving waters cause numerous environmental impacts, including reduced sunlight penetration, blanketing of fish spawning substrates, and transport of pollutants contributing to aquatic pollution. For the assessment of such impacts, it is important to measure solids concentrations in both runoff and snowmelt. In this study, accuracies of three analytical methods used to measure solids were assessed: (a) A TSS (total suspended solids) method, (b) Suspended sediment method (SSC-B), and (c) a multiple filter method (MFM). For rainfall runoff samples containing 90% of particles smaller than 5 μm, the MFM measurements produced concentrations significantly higher than those obtained with SSC-B and TSS methods, at a 95% confidence level. In the case of snowmelt runoff, the SSC-B and MFM methods yielded similar concentrations, which were 10-20% higher than those measured by the TSS method, and the coefficient of variation of repeated TSS readings was up to three times higher than that of the former methods. The results indicate the importance of choosing the “best” analytical method for assessing the operational and environmental impacts of solids conveyed by urban runoff and snowmelt.

National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-31948 (URN)6459d43d-e938-47af-b8b8-776b140c4fc2 (Local ID)6459d43d-e938-47af-b8b8-776b140c4fc2 (Archive number)6459d43d-e938-47af-b8b8-776b140c4fc2 (OAI)
Conference
International Conference on Urban Drainage : 11/09/2011 - 15/09/2011
Note
Godkänd; 2011; 20120510 (ysko)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-02-26Bibliographically approved
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