Contaminated sediments

Remediation of contaminated sediments is vital in order to reach national environmental goals of a Non-ToxicEnvironment and A Balanced Marine Environment, Flourishing Coastal Areas as well as Flourishing Lakes and Streams, and the United Nations 14 sustainable development goal of Life Below Water. Sediment remediation is however costly, making prioritizing of efforts to sites where they are the most effective vital. This is today challenging, as current risk assessment largely depends on the total sediment concentrations of the contaminants, while the mobility, and bioavailability of the contaminants are governed by the dissolved fraction(C). Passive sampling methods offer well established approaches for quantification of C in natural waters and sediments, yet are not regularly used in monitoring or for risk assessment purposes. MOBILITY (Mobility, Bioavailability and Toxicity of Sediment Contaminants) aims to demonstrate the applicability of passive sampling approaches by linking C to contaminant mobility, bioavailability and toxicity in resuspension experiments covering typical sediment characteristics. Generated knowledge will be used to – in dialogue with stakeholders and end users - develop recommendations for the use of passive sampling approaches of organic contaminants and metals in risk assessment and environmental monitoring of sediments. The expected outcome will support several steps in contaminated sediment risk assessments, including mapping of contaminant transportation and selection of risk-based assessment criteria, through recommendation for the use of passive samplers, and by providing a basis for how the risk of contaminated sediments relates to sediment characteristics (e.g., grain size distribution and organic carbon content). MOBILITY will further provide the missing link to integrate chemical (Criterion 8.1) and biological (Criterion 8.2) indicators within the EU Marine Strategy Framework Directive.

Sofi Jonsson, Stockholm University
sofi.jonsson@aces.su.se
Phone: +460701427944

5 000 000 SEK

The aim is to clarify how physical and chemical factors and microbal activity control pulp fiber decomposition and Hg methylation rates in a Baltic sea bay.     Pulp fiber sediments are significant sources of organic pollutants and mercury (Hg) to aquatic food webs in coastal areas, lakes, and rivers. Persistent pollutants such as PCBs, dioxins, DDT, and Hg can spread over large areas when the fibers are decomposed by microbes to fine particulate and colloidal matter. Furthermore, Hg bound in pulp is methylated during the process, leading to release of toxic and bioaccumulative methyl mercury (MeHg). The pulp organic carbon (C) content is high, but nitrogen (N) and phosphorus (P) contents are low. In order to grow well on pulp, microbes have to assimilate N and P from the water or from settled plankton algaea. Whereas N can be assimilated through N-fixation, P-assimilation is dependent on phosphate supplies. Sulfate-reducing bacteria (SRB) are known to fix N and also to cause Hg methylation. We will determine the role of N-fixation, sulfate reduction, sulfur oxidation, phosphate supply, and supply of algal matter in pulp fiber decomposition and Hg methylation.This willinvolve quantifying genes and gene expressions essential for Hg methylation, N-fixation, sulfate reduction, and sulfur oxidation, and characterisation of the microbial community and its function. Our studies will include field measurements in pulp fiber sediment cores (stratigraphy), but also lab experiments designed to test effects of  temperature, phosphate additions, additions of freeze-dried algal cells, and pulp fiber properties on fiber decomposition and Hg methylation rates. Comparing with element stratigraphies obtained  in 2004 will allow us to estimate fiber decomposition rates.  Knowing what factors limit pulp fiber decomposition and Hg methylation rates makes it possibleto reduce risks of pollutant release by adequate water management and selective removal of highrisk sediment.

Olof Regnell, Lund University
olof.regnell@biol.lu.se
Phone: +46462223781

4 057 793 SEK

The objective is to improve current ecological risk assessment (ERA) procedures for contaminated sediments in Sweden, by increasing ecological relevance and site-specificity of the ERA using new measurements of bioavailability and new DNA methods to assess the effects of contaminants on biodiversity, community structure and ecosystem functions of the whole benthic community. Methods: We will use a new ERA model developed by the Norwegian Environment Agency for assessment of marine sediments and test it on a highly topical case the outer harbor of Oskarshamn. The inner harbor was recently remediated through dredging to decrease the dispersal of dioxin and metals to the Baltic Sea. The outer harbor was not part of the remediation as it is deeper and more difficult to dredge. It has been extensively studied for contaminants and hydrography and is a very actual case-study for testing ERA of marine and brackish water sediments in Sweden. We will start with a screening ERA based on existing data and then increase site-specificity by doing a mesocosm experiment with sediments collected from Oskarshamn. We will measure the spreading risks to aquatic biota and humans and assess the effects of the complex contaminant mixture on benthic community structure (DNA barcoding) and functions (microbial denitrification) and by using specific biomarkers (embryonic malformations in amphipods). We will also evaluate how shifts in environmental conditions (increased temperature, resuspension and hypoxia) affect the risks. Outcome: Using a weight-of-evidence (WOE) analysis with the TRIAD method, we will evaluate which measurement endpoints are the most useful for the ERA. Our WOE will provide a clear Matrix table that allows to compare risk values under various scenarios and help decision-making and prioritization between contaminated sites and where remediation is mostly needed. The project will fill current gaps of knowledge and help the SEPAto develop Swedish ERA guidelines.

Jonas Gunnarsson, Stockholm University
jonas.gunnarsson@su.se
Phone: +468164253

4 869 532 SEK

Chemical pollution from anthropogenic activities is of major concern for different environmental authorities worldwide. Environmental pollutants are accumulated in aquatic ecosystems at concentrations well above ambient levels, which poses detrimental effects on the resident biota and ecosystem functioning. In addition, in a changing global climate where the transport and partitioning of hazardous chemicals are expected to be altered, it is crucial to deepen our understanding of the potential impacts of anthropogenically-derived pollutants on aquatic environments and their food webs. Bioindication is an important tool used in the implementations of the EU environmental legislation for the assessment of the quality status of different natural environments. Due to their vast metabolic versatility, microbes inhabit a wide range of environments, including contaminated sediments. Thus, microbial communities may be used as rapid and sensitive indicators of environmental disturbance induced by the occurrence of contaminants. In the project here proposed, we will develop a cost-time-efficient standardized method for a rapid assessment of contaminated sediments using structural and functional properties of natural microbial communities as bioindicators, with Hg as model pollutant. A multi-omics (DNA/RNA) approach will be developed to conduct in situ molecular analyses from field and laboratory studies where Oxford Nanopore sequencing technologies will be employed. We will identify microbial taxa, functional genes, and metabolic pathways characteristic of the naturally occurring communities, and capable of responding to loads of pollutants under a wide range of physico-chemical profiles. Relevant genes and microbial taxa will be integrated in a modelling approach to link patterns of gene expression and community structure to loads of pollutants and bioaccumulation in the food web, which can have important implications in pollutant tracking, monitoring and risk assessment.

Agneta Andersson, Umeå University
agneta.andersson@umu.se
Phone: +46907869845

4 752 494 SEK

Mercury constitutes a severe threat to ecosystem viability and human health, mainly through the formation and spread of neurotoxic methylmercury (MeHg) in aquatic ecosystems. Therefore, MeHg is a critical “risk-determining” component in contaminated sediment. Current risk assessments are inadequate since they are based on measured concentrations only and do not include the potential for MeHg formation and spread. Recent advances in process understanding of MeHg formation and the development of new state-of-the art technologies in synchrotron radiation sources and mass spectrometry now enable the transformative research required to implement MeHg formation and spread in refined risk assessments. In this project we will: (i) determine the chemical forms of inorganic Hg, Hg(II), and the composition of natural organic matter (NOM) in contaminated sediment. These are the two principal controlling factors for MeHg formation; (ii) identify at which conditions MeHg formation is limited by either of these factors or a combination of both. This will allow to assess if the risk for MeHg formation is controlled by an inherent property of the contaminated sediment itself (Hg(II) speciation),or determined by the biogeochemistry of the surrounding environment (NOM inputs). We will also (iii) evaluate and optimize the use of stable Hg isotope measurements to trace the spread of Hg(II) and MeHg from contaminated sediment to surrounding water mass, sediment and biota. This emerging technology is the most potent for reliable source tracing of Hg and MeHg in the environment. Overall, the project deliverables will be important for refining risk assessment of Hg contaminated sediment, including to predict the potential impact of environmental change scenarios and tailor land use and aquatic resource management nearby the site, as well as for optimizing mitigation measures.

Erik Björn, Umeå University
erik.bjorn@umu.se
Phone: +46907865189

4 995 600 SEK

Fiberbanks consist of wood fibers from previous pulp production and contain toxic substances such as persistent organic pollutants (POPs, e.g., PCBs and DDTs) and heavy metals (e.g., Hg and Pb). Pollutants from fiberbanks can be mobilized to the environment continuously through e.g. diffusion and advection. Recently large amount of ebullition gas production has been revealed during previous studies of fiberbanks. However, to date it is not possible to assess the risks related to gas-mediated contaminant dispersal because there is no appropriate sampling equipment and methods for field in-situ measurements. The lack of ebullition gas data and associated contaminants dispersion largely hindered the risk assessment of fiberbanks, and more importantly, the environmental effectiveness of in-situ remediation strategies. In this project we aim to (i) develop a method that allow in-situ sampling of ebullition gas from fiberbanks (ii) to quantify and fingerprint the environmental drivers of semi-volatile contaminants (POPs and Hg) and greenhouse gas (GHG) emission (iii) compare these results for both intact and remediated sites, and (iv) create a risk assessment procedure that takes into account the transport of pollutants from gas ebullition to support future assessments and remediation measures.  The overall objective is to be able to contribute with the necessary knowledge on the magnitude and drivers of contaminants that are emitted from fiberbanks via gas ebullition. In the long run, this will aid authorities to make well informed decisions on priority setting and sustainably management of contaminated fiberbanks.

Paul Frogner-Kockum, Swedish Geotechnical Institute
paul.frogner-kockum@swedgeo.se
Phone: +4640356773

4 987 136 SEK