| 1. |
- Gaggini, Elly Lucia, 1993, et al.
(författare)
-
Assessment of fine and coarse tyre wear particles along a highway stormwater system and in receiving waters : Occurrence and transport
- 2024
-
Ingår i: Journal of Environmental Management. - : Elsevier. - 0301-4797 .- 1095-8630. ; 367:September
-
Tidskriftsartikel (refereegranskat)abstract
- Tyre wear has been identified as a major road-related pollutant source, with road runoff transporting tyre wear particles (TWP) to adjacent soil, watercourses, or further through stormwater systems. The aim of this study was to investigate the occurrence and transport of TWP along a stormwater system. Water and sediment have been sampled at selected points (road runoff, gully pots, wells, outlet to a ditch, and stream) through a stormwater system situated along a highway in Sweden during November and December 2022, and March 2023. As there is limited data on the size distribution of TWP in different environmental media, especially in the size fraction <20 μm, the samples were fractioned into a fine (1.6–20 μm) and a coarse (1.6–500 μm) size fraction. The samples were analysed using a combination of marker compounds (benzene, α-methylstyrene, ethylstyrene, and butadiene trimer) for styrene-butadiene rubbers with PYR-GC/MS from which TWP concentration was calculated. Suspended solids were analysed in the water samples, and organic content was analysed in the sediment samples. TWP was found at nearly all locations, with concentrations up to 17 mg/L in the water samples and up to 40 mg/g in the sediment samples. In the sediment samples, TWP in the size fraction 1.6–20 μm represented a significant proportion (20–60%). Correlations were found between TWP concentration and suspended solids in the water samples (r = 0.87) and organic content in the sediment samples (r = 0.72). The results presented in this study demonstrate that TWP can be transported to the surrounding environment through road runoff, with limited retention in the studied stormwater system.
|
|
| 2. |
- Toller, Erik A.L.
(författare)
-
An Analytic Element Model for Intersecting and Heterogeneous Fractures in Groundwater Flow
- 2022
-
Ingår i: Water Resources Research. - : American Geophysical Union (AGU). ; 58:5
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract Intersecting fractures often dominate the rock though which groundwater flows and they represent a crucial feature in groundwater models. In this paper, limitless analytic elements were used to model intersecting and heterogeneous fractures with either high or low transmissivity relative to that of the surrounding medium. To handle the singular behavior at the intersections, fractures were modeled as multiple elements, the tips of which meet at the point of intersection. The same approach was used to model heterogeneous fractures where the transmissivity is discontinuous along a fracture. Representing the fractures analytically in the continuum allows for an exact representation of the groundwater exchange between the fractures and the continuum. Thereby producing an accurate model of flow through a network of fractures in a continuum. This solution is capable of accurately computing the groundwater flow for both a network of fractures with a high transmissivity and an assembly of heterogeneous fractures near a tunnel.
|
|
| 3. |
- Zhaka, Vasiola, et al.
(författare)
-
Observations of Snow–Slush–Snow Ice Transformation and Properties of Brash Ice in Ship Channels
- 2023
-
Ingår i: Water. - : MDPI. - 2073-4441. ; 15:13
-
Tidskriftsartikel (refereegranskat)abstract
- The thickness and properties of brash ice are usually compared with the properties of the surrounding level ice. The differences between these ice types are important to understand since the consolidated brash ice layer is typically assumed to have the same properties as level ice. Therefore, significant effort in the measurement campaign during the winters of 2020–2021, 2021–2022, and 2023 was made to develop a better understanding of the full-scale brash ice channel development. The channels were located near the shore in the Bay of Bothnia, Luleå, Sweden. The main parameters investigated were the snow, slush, and total ice thicknesses, including ice formed from freezing water and from freezing slush as well as the ice microstructure and strength. To our knowledge, this is the first paper to report the influence of snow in brash ice channels. It was observed that a significant amount of snow covered the brash ice channels between the ship passages. After each ship passage, the snow was submerged and formed slush-filled voids, which thereafter transformed into snow ice (SI) clusters frozen together with columnar ice. The SI content in the brash ice and side ridges was estimated from image analyses. The analyses showed that the snow ice content was 73% in level ice in the vicinity of the ship channel, 58% in the side ridges of the channel, and 21% in the middle of the test channel, whereas in the main channel, the SI contents were 54%, 43%, and 41% in each location, respectively.
|
|
| 4. |
- Zhaka, Vasiola, 1992-, et al.
(författare)
-
Snow effects on brash ice and level ice growth
- 2024
-
Ingår i: Journal of Glaciology. - : Cambridge University Press. - 0022-1430 .- 1727-5652.
-
Tidskriftsartikel (refereegranskat)abstract
- Brash ice formation and accumulation occur at a faster rate in ship channels, harbours and turning areas compared to the surrounding level ice. Accurate prediction of brash ice thickness plays an important role in addressing operational challenges and optimisation of ice management strategies. This study enhances existing brash ice growth models by considering the effects of snow and accounting for brash ice expulsion towards the sides of ship channels at each passage. To validate the influence of these critical factors on brash ice thickness, three distinct ship channels located in the Bay of Bothnia, Luleå, Sweden, were investigated. For two test channels formed for study purposes, the slower growth rate of brash ice caused by snow insulation was more prominent than the brash ice growth acceleration caused by the snow–slush–snow ice transformation. In the third channel characterised by frequent navigation, the transformation of slush into snow ice played a more substantial role than snow insulation. In both test channels, the brash ice growth model performed optimally, assuming a 10% expulsion of brash ice sideways at each vessel passage. In the third, wider and more frequently navigated channel, a 1.2% brash ice expelling coefficient predicted well the measured brash ice thicknesses.
|
|
| 5. |
- Ngubane, Zesizwe, et al.
(författare)
-
Multi-criteria decision analysis framework for engaging stakeholders in river pollution risk management
- 2024
-
Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 14:1
-
Tidskriftsartikel (refereegranskat)abstract
- Water pollution presents a substantial environmental challenge with extensive implications for water resources, ecosystem sustainability, and human health. Using a South African catchment, this study aimed to provide watershed managers with a framework for selecting best management practices (BMPs) to reduce pollution and the related risk to river users, while also including the perspectives of key catchment stakeholders. The framework encompassed the identification of and consultation with key stakeholders within the catchment. A Multi-Criteria Decision Analysis (MCDA) methodology using the Simple Multi-Attribute Rating Technique for Enhanced Stakeholder Take-up (SMARTEST) was used to identify and prioritise suitable BMPs in a case study. Decision alternatives and assessment criteria as well as their weights were derived based on stakeholder responses to a two-stage survey. Stakeholders included those utilising the river for domestic and recreational purposes, municipal representatives, scientists, NGOs, and engineers. The assessment of decision alternatives considered environmental, economic, and social criteria. The aggregated scores for decision alternatives highlighted the significance of involving stakeholders throughout the decision process. This study recommends the pairing of structural and non-structural BMPs. The findings provide valuable insights for catchment managers, policymakers, and environmental stakeholders seeking inclusive and effective pollution mitigation strategies in a catchment.
|
|
| 6. |
- Tikkanen, Toni
(författare)
-
3. Waste management and nutrient flows in the city of Turku : A detailed N and P flow study to estimate the capacity of biowaste sorting to contribute to nutrient recycling
- 2003. - 1
-
Ingår i: Urban Environmental Management. - Uppsala : Baltic University Press. - 9197001759 ; , s. 27-41
-
Bokkapitel (populärvet., debatt m.m.)abstract
- A detailed quantitative study of flows of nitrogen and phosphorus in all organic waste in Turku was made to evaluate the potential of recycling of nutrients. Both inputs and outputs in all municipal and private sewerage, nutrient-containing fluent and solid waste flows were estimated. These included municipal and private sewerage, municipal solid waste, and municipal as well as private composting. The volume or weight of each of these was measured as well as their content of N and P either measured or estimated using reference values from literature. The total flows for the 170,000 inhabitants and their animals were found to be 3,074 kg of N and 583 kg of P per day. 64% of the inputs were found in the municipal wastewater, 11% in private sewarage, 10% in solid organic waste sent to incineration and 7% in organic waste sent to landfill. The major flows of output nitrogen included 53% (1,647 kg/day) to surface waters and 23% (765 kg/day), to sludge, while for phosphorus 15% (90 kg/day) went to surface waters and 61% (368 kg/day) to sludge. Only 1% of the nutrients were recycled for new agricultural production. If separate sorting of biowaste is achieved (planned for 2005) this figure will increase to 7% and with maximum recycling amount to 15-16%.
|
|
| 7. |
- Vinas, Victor, 1988, et al.
(författare)
-
Cross-connections in drinking water distribution networks: Quantitative microbial risk assessment in combination with fault tree analysis and hydraulic modelling
- 2022
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 831
-
Tidskriftsartikel (refereegranskat)abstract
- Deficiencies in drinking water distribution networks, such as cross-connections, may lead to contamination of the drinking water and pose a serious health risk to consumers. Cross-connections and backflows are considered among the most severe public health risks in distribution networks. The aim of this paper was to provide a framework for estimating the risk of infection from cross-connection and backflow events. Campylobacter, norovirus, and Cryptosporidium were chosen as reference pathogens for this study. The theoretical framework was constructed based on the fault tree analysis methodology. National aggregated cross-connection incident data was used to calculate the probability of a contamination event occurring in Swedish networks. Three risk cases were evaluated: endemic, elevated, and extreme. Quantitative microbial risk assessment (QMRA) was used to assess daily risk of infection for average national estimates. The framework was also evaluated using local data from the Gothenburg network. The daily risk of infection from cross-connection and backflow events in Swedish networks was generally above an acceptable target level of 10−6 for all reference pathogens and modelled cases; the exception was for the Gothenburg system where the risk was lower than 10−7. An outbreak case study was used to validate the framework results. For the outbreak case study, contaminant transport in the network was simulated using hydraulic modelling (EPANET), and risk estimates were calculated using QMRA. The outbreak simulation predicted between 97 and 148 symptomatic infections, while the epidemiological survey conducted during the outbreak reported 179 cases of illness. The fault tree analysis framework was successfully validated using an outbreak case study, though it was shown on the example of Gothenburg that local data is still needed for well-performing systems. The framework can help inform microbial risk assessments for drinking water suppliers, especially ones with limited resources and expertise in this area.
|
|
| 8. |
- Anandhi, Aavudai, et al.
(författare)
-
Evaluation of Climate Model Performance for Water Supply Studies : Case Study for New York City
- 2019
-
Ingår i: Journal of water resources planning and management. - : ASCE-AMER SOC CIVIL ENGINEERS. - 0733-9496 .- 1943-5452. ; 145:8
-
Tidskriftsartikel (refereegranskat)abstract
- Evaluating the suitability of data from global climate models (GCMs) for use as input in water supply models is an important step in the larger task of evaluating the effects of climate change on water resources management such as that of water supply operations. The purpose of this paper is to present the process by which GCMs were evaluated and incorporated into the New York City (NYC) water supply's planning activities and to provide conclusions regarding the overall effectiveness of the ranking procedure used in the evaluation. A suite of GCMs participating in Phase 3 of the Coupled Model Intercomparison Project (CMIP3) were evaluated for use in climate change projections in the watersheds of the NYC water supply that provide 90% of the water consumed by NYC. GCM data were aggregated using the seven land-grid points surrounding NYC watersheds, and these data with a daily timestep were evaluated seasonally using probability-based skill scores for various combinations of five meteorological variables (precipitation, average, maximum and minimum temperatures, and wind speed). These are the key variables for the NYC water supply because they affect the timing and magnitude of water, energy, sediment, and nutrient fluxes into the reservoirs as well as in simulating watershed hydrology and reservoir hydrodynamics. We attempted to choose a subset of GCMs based on the average of several skill metrics that compared baseline (20C3M) GCM results to observations. Skill metrics for the study indicate that the skill in simulating the frequency distributions of measured data is highest for temperature and lowest for wind. However, our attempts to identify the best model or subgroup of models were not successful because we found that no single model performs best when considering all of the variables and seasons.
|
|
| 9. |
|
|
| 10. |
- Björnerås, Caroline, et al.
(författare)
-
The lake as an iron sink - new insights on the role of iron speciation
- 2021
-
Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541 .- 1872-6836. ; 584
-
Tidskriftsartikel (refereegranskat)abstract
- The solubility and behavior of iron (Fe) in natural waters is tightly linked to Fe speciation, and Fe speciation likely influences how Fe distributes between the water column and sediments. In this study, the function of a lake as an Fe sink, with focus on the role of Fe speciation, was assessed for Lake Bolmen in southern Sweden. We found that a large fraction of the Fe flowing in to the lake was efficiently lost by sedimentation in the lake basin. Fe in inflowing water was a mix of organically complexed mononuclear Fe, Fe-(oxy)hydroxides and Fe-bearing clays, while surface sediments were composed of Fe-(oxy)hydroxides, Fe-bearing clays, Fe-bearing silicates and Fe sulfides. The absence of organically complexed Fe in the surface sediments indicates that the lake is mainly a sink for minerogenic fractions. Furthermore, while lakes are considered to be sinks of Fe, it has been suggested that this function may be impaired by increasing precipitation and consequently shorter water residence time. In this study there were large within- and between-year variations in precipitation and Fe concentrations. However, rather than smaller Fe losses to the sediments during wet years, within-lake losses tended to be larger due to higher loading of Fe from the catchment. Thus, forecasted increases in precipitation may result in enhanced catchment export and Fe loading to lakes, and subsequently enhanced Fe sequestration in sediments.
|
|
