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Stenungsund bay area
Stenungsund is a municipality at the Swedish west coast and is host to the biggest chemical cluster in Sweden.

Case Study: Stenungsund Bay - the biggest chemical cluster in Sweden

Pågående forskning
2016 - 2021
Martin Hassellöv and Lena Gipperth

Kort beskrivning

Stenungsund is a municipality at the Swedish west coast, about 40 km north of Gothenburg. It is host to the biggest chemical cluster in Sweden, centered around a steam cracker that produces ethylene and various fuel gases, which are then used by a range of companies for the production of polyethylene, polyvinyl chloride (PVC), amines, detergents, and various other chemicals. Additionally, there are several harbors situated along the coast.

The area of Stenungsund has been monitored and studied for a long time, and should therefore be well suited for a study with a system perspective on chemical flows. The starting point for this study has been the status of an area in the Askeröfjorden, close to the central town and the industrial area.

We have asked ourselves why chemicals are present or not present in the water column and the sediments. We also study what ecological risks these chemicals have and what drives pollution of chemicals to the fjord. Is the legislation sufficient to implement objectives on good water status (e.g. Water Framework Directive) and a non-toxic environment (Swedish official environmental objective)? If not, is there a need to enforce current legislation or to change it and in such case how?

Work process

In this study the multi-disciplinary team uses modelling, measurements, lab-experiments, interviews and desktop studies to examine the current chemical status in the area, the flow of chemicals into and within the area, its impact and how the policy instruments perform in meeting policy objectives. There is ongoing discussions and information exchange with the local authority, the county administration, industry and NGOs.

Case study

This case study will allow us to (i) describe the chemical risk in the area in detail, (ii) pinpoint particularly problematic compounds and sources, (iii) make concrete risk management suggestions, and (iv) suggest measures that give improvements of company practises, all within Swedish and EU laws and regulations.


As part of the case study, the team has summarized relevant data-sets and reference list for reports and papers that deal specifically with chemical pollution or environmental effects possibly linked to chemical pollution in Stenungsund. From this data, a dataset compiling the chemicals that are present in the different reports has also been produced. A short summary of the document and dataset is presented below:

  • Modelled consumer-release data. Model data estimating the release of 2 366 chemicals from consumers.
  • NICE chemical measurements. Measurements in water of around 150 chemicals in the marine environment of Askeröfjorden.
  • “Bohuskustens Vattenvårds Förbund” chemical measurements. Measurements in biota and sediments. Old datasets available via IVL (biota) and SGU (sediments). The latest monitoring campaign was performed in 2017.
  • “Utsläpp i siffror”. Emissions to water (and air) reported by A and B permit installations in Stenungsund. The data is obtainable via Naturvårdsverket and are the same data as reported in the mandatory parts of the environmental reports.
  • C-permit data. 21 unique reported entries from C-permit installations in Stenungsund.
  • Agricultural land-use. Obtained from Jordbruksverket. It shows that 82% of the available agricultural land is used either as pastures or are in tread.
  • Nutrient and waterflows into askeröfjorden. Data obtained from SMHI, originally determined using the model S-HYPE.

A manuscript describing a method for predicting the emission of chemicals from consumers and consumer products to wastewater is under development. The method was used to estimate the emissions of chemical preparations, prescription pharmaceuticals and chemicals leaching from textiles during washing (Modelled consumer release data from the summary in previous point).
A compilation of REACH-registration data has resulted in curated datasets of PNECs. This data is being analyzed and cross-referenced with the summary mentioned above with the goal of determining whether or not the REACH-registration is protective, or if there could be a systematic glitch, which could lead to identify a chemical as less hazardous than what it potentially could be.

Storm water runoff and presence of pollutants in the bay

Part of the focus of the field studies in Stenungsund related to FRAM has been on storm water runoff, including the presence of organic pollutants and inorganic material. Natural waters are recipients of different types of contaminants derived from anthropogenic activities. With the implementation and optimization of wastewater treatment facilities and the separation of relatively clean storm water from domestic or industrial wastewater, the relative importance of these discharges as drivers for water pollution has increased.

Storm water runoff has been identified as a significant nonpoint source of contaminants to waterbodies close to urban centres. Apart from organic substances that are carried with the storm water, particles (that have been deposited in surfaces or stored in small ponds under dry conditions) are also carried away during rainfall affecting the chemical composition of the recipients as well as the water quality.

In June of 2018 Prof. Werner Brack’s analytical team from the Helmholtz-Centre for Environmental Research GmbH – UFZ (Leipzig, Germany) one of the world’s leading environmental chemistry groups, made a dedicated sampling campaign in the Stenungsund area together with researchers from FRAM. Fluxes of 300+ chemicals into the environment in Stenungsund have been identified, part of those corresponding to samples from Stenunge Å which acts as storm water collector for a district of Stenungsund. Extracts from samples from the water body in the bay, containing concentrated organic substances, will be used to identify possible effects of the mixture on selected organisms.

In parallel to that study, a preliminary survey of the presence of inorganic contaminants associated to storm water runoff was conducted.

During 2019, a study on the occurrence of inorganic particles in storm water was carried out in the area. This study is complimentary to the one performed in 2018 mentioned above. The concentration of inorganic particles was compared in water samples collected during a dry period and during a rain event.

The aim of the study was to estimate the contribution of contaminants from the catchment area, which includes heavy traffic roads, an industrial complex, and a residential area and discharges the fjord. The sampling site was a small stream in Stenungsund, Sweden and the runoff area consists of industrial and residential areas. This study evaluates two relatively new methods for identifying inorganic particulate pollutants in storm water: scanning electron microscopy with automatic particle identification (SEM-EDX) and single particle ICP-MS. The water samples were filtered using membranes and analysed with SEM-EDX. The filtered samples were analysed further with single particle ICPMS. This type of studies highlights the overall distribution of natural particles since they are several orders of magnitude more abundant than anthropogenic particles.

Plastic pollution

In addition, FRAM researchers have also participated in assignments related to plastic pollution. During 2019, a study on the examination of micro-debris along Bohuslän beaches and in sediments near Stenungsund was produced as part of a parallel assignment for the Swedish environmental agency, which is publicly available.1 The beach sampling outside Stenungsund took place in the proximity of Stenunge Å. The results from the area were compared with samples taken in other zones in the same study. Stenungsund samples showed a larger amount of plastics related to plastic production suggesting that local sources of microplastics and waste during production and transport have a significant impact on local pollution levels.

Legal analysis of the chemical status

The legal analysis of the chemical status in Askeröfjorden and sources of pollution affecting this status has during 2019 been focusing on the VISS data, showing four substances contributing to the exceedance of the water quality standard (antracen, mercury, TBT, brominated diphenylethers). The intention is to understand why the levels are exceeded and the role of formal rules of consideration and their enforcement. In the summer of 2019, a new PhD-student (Julia Johansson) started a project aiming at analyzing gender in chemicals legislation. One of her first tasks is to contribute to the legal part of the Stenungsund case study but with the intention to be able to further use this material in her analysis of gender and power distribution in relation to different actors and substances. Results are expected to be presented in 2020.