Inconsistencies in How Environmental Risk Is Evaluated in Sweden for Dumping Dredged Sediment at Sea

Bruce, P.; Bradshaw, C.; Ohlsson, Y.; Sobek, A.; Christiernsson, A
2021 | Front. Mar. Sci. | 8

Effects of organic carbon origin on hydrophobic organic contaminant fate in the Baltic Sea

Nybom, I.; Horlitz, G.; Gilbert, D.; Berrojalbiz, N.; Martens, J.; Arp, H-P., H.; Sobek, A.
2021 | Environ. Sci. Technol.

The transport and fate of hydrophobic organic contaminants (HOCs) in the marine environment are closely linked to organic carbon (OC) cycling processes. We investigated the influence of marine versus terrestrial OC origin on HOC fluxes
at two Baltic Sea coastal sites with different relative contributions of terrestrial and marine OC. Stronger sorption of the more than four-ring polycyclic aromatic hydrocarbons and penta-heptachlorinated polychlorinated biphenyls (PCBs) was observed at the marine OC-dominated site. The site-specific partition coefficients
between sediment OC and water were 0.2−1.0 log units higher at the marine OC site, with the freely dissolved concentrations in the sediment pore-water 2−10 times lower, when compared with the terrestrial OC site. The stronger sorption at the site characterized with marine OC was most evident for the most hydrophobic PCBs, leading to reduced fluxes of these compounds from sediment to water. According to these results, future changes in OC cycling because of climate change, leading to increased input of terrestrial OC to the marine system, can have consequences for the availability and mobility of HOCs in aquatic systems and thereby also for the capacity of sediments to store HOCs.

Insights into the factors influencing mercury concentrations in tropical reservoir sediments

Baptista-Salazar, C.; Quadra, G.R.; Sobek, A.; Jonsson, S.
2021 | Environ. Sci.-Process Impacts

Thousands of dams are currently under construction or planned worldwide to meet the growing need for electricity. The creation of reservoirs could, however, lead to conditions that promote the accumulation of mercury (Hg) in surface sediments and the subsequent production of methylmercury (MeHg). Once produced, MeHg can bioaccumulate to harmful levels in organisms. It is unclear to what extent variations
in physical features and biogeochemical factors of the reservoir impact Hg accumulation. The objective of this study was to identify key drivers of the accumulation of total Hg (THg) in tropical reservoir sediments. The concentration of THg in all analyzed depth intervals of 22 sediment cores from the five contrasting reservoirs investigated ranged from 16 to 310 ng g1 (n ¼ 212, in the different sediment cores, the maximum depth varied from 18 to 96 cm). Our study suggests reservoir size to be an important parameter determining the concentration of THg accumulating in tropical reservoir
sediments, with THg ranging up to 50 ng g1 in reservoirs with an area exceeding 400 km2 and from 100 to 200 ng g1 in reservoirs with an area less than 80 km2. In addition to the reservoir size, the role of land use, nutrient loading, biome and sediment properties (e.g., organic carbon content) was tested as potential drivers of THg levels. The principal component analysis conducted suggested THg to be related to the properties of the watershed (high degree of forest cover and low degree of agricultural land use), size and age of the reservoir, water residence time and the levels of nutrients in the reservoir. A direct correlation between THg and tested variables was, however, only observed with the area of the reservoir.

Micropollutants in four Brazilian water reservoirs

Quadra, G.R.; Li, Z.; Barros, N.; Roland, F.; Sobek, A.
2021 | Limnologica | 90

Temporal and Spatial Variability of Micropollutants in a Brazilian Urban River

Quadra, G.R.; Li, Z.; Silva, P.S.A.; Barros, N.; Roland, F.; Sobek, A.
2021 | Arch. Environ. Contam. Toxicol. | 81 (142-154)

Assessing the social-ecological status of the Baltic Sea

Blenckner, T.; Möllmann, C.; Lowndes, J.S.; Griffiths, J.R.; Campbell, E.; De Cervo, A.; Belgrano, A.; Boström, C.; Fleming, V.; Frazier, M.; Neuenfeldt, S.; Niiranen, S.; Nilsson, A.; Ojaveer, H.; Olsson, J.; Palmlöv, C.S.; Quaas, M.; Wilfried, R.; Sobek, A.; Viitasalo, M.; Wikström, S.A.; Halpern, B.S.
2021 | People Nat. | 00 (1-17)

The Baltic Health Index (BHI): Assessing the social-ecological status of the Baltic Sea

Blenckner, T; Mollmann, C; Lowndes, JS; Griffiths, JR; Campbell, E; De Cervo, A; Belgrano, A; Bostrom, C; Fleming, V; Frazier, M; Neuenfeldt, S; Niiranen, S; Nilsson, A; Ojaveer, H; Olsson, J; Palmlov, CS; Quaas, M; Rickels, W; Sobek, A; Viitasalo, M; Wikstrom, SA; Halpern, BS
2021 | People Nat. | 3 (2) (359-375)
ecosystem-based management , framework , health , management , management targets , marine ecosystem , region , shift , social-ecological system , sustainability
Improving the health of coastal and open sea marine ecosystems represents a substantial challenge for sustainable marine resource management, since it requires balancing human benefits and impacts on the ocean. This challenge is often exacerbated by incomplete knowledge and lack of tools that measure ocean and coastal ecosystem health in a way that allows consistent monitoring of progress towards predefined management targets. The lack of such tools often limits capabilities to enact and enforce effective governance. We introduce the Baltic Health Index (BHI) as a transparent, collaborative and repeatable assessment tool. The Index complements existing, more ecological-oriented, approaches by including a human dimension on the status of the Baltic Sea, an ecosystem impacted by multiple anthropogenic pressures and governed by a multitude of comprehensive national and international policies. Using a large amount of social-ecological data available, we assessed the health of the Baltic Sea for nine goals that represent the status towards set targets, for example, clean waters, biodiversity, food provision, natural products extraction and tourism. Our results indicate that the overall health of the Baltic Sea is suboptimal (a score of 76 out of 100), and a substantial effort is required to reach the management objectives and associated targets. Subregionally, the lowest BHI scores were measured for carbon storage, contaminants and lasting special places (i.e. marine protected areas), albeit with large spatial variation. Overall, the likely future status of all goals in the BHI averaged for the entire Baltic Sea is better than the present status, indicating a positive trend towards a healthier Baltic Sea. However, in some Baltic Sea basins, the trend for specific goals was decreasing, highlighting locations and issues that should be the focus of management priorities. The BHI outcomes can be used to identify both pan-Baltic and subregional scale management priorities and to illustrate the interconnectedness between goals linked by cumulative pressures. Hence, the information provided by the BHI tool and its further development will contribute towards the fulfilment of the UN Agenda 2030 and its Sustainability Development Goals. A free Plain Language Summary can be found within the Supporting Information of this article. A free Plain Language Summary can be found within the Supporting Information of this article.

Inconsistencies in How Environmental Risk Is Evaluated in Sweden for Dumping Dredged Sediment at Sea

Bruce, P; Bradshaw, C; Ohlsson, Y; Sobek, A; Christiernsson, A
2021 | Front. Mar. Sci. | 8
aromatic-hydrocarbons , bioavailability , contaminant , contaminated sediments , ecosystem , fish , impact , regulation , resuspension , risk assessment , risk evaluation , risk management , sea dumping , sediment , site , toxicity , water
Millions of tons of dredged sediment are dumped at sea annually. International conventions limit dumping when there is a risk of adverse ecological effects, for example if the sediment is contaminated. However, the perception of risk differs substantially among stakeholders and in Sweden there is a lack of guidelines for how to address such risk. In the current study, we examined exemptions to the Swedish ban on dumping at sea, to explore the extent of dumping and how ecological aspects were considered in the evaluation of risks. We analyzed data from all cases granted exemption by county administrative boards and all court cases considering exemption to the ban from the beginning of 2015 to June 2020. We found that while dumping is the least common alternative management method for dredged sediment in total number of cases (98/792), dumping is the main method in terms of volume (30.8/38.2 million m(3)). When considering exemptions, the courts mainly evaluated the risk of exposure to contaminants and resuspended sediment for the environment adjacent to the dumpsite. The risks from contaminants were characterized based on various lines of reasoning, mainly relying on reference values not based on a scientific correlation to environmental risk. We argue that the evaluations were not in line with current regulations and international conventions as they insufficiently accounted for the ecotoxicological risk of the dumped sediment. These issues are potentially similar in other Baltic Sea countries, where there is a similar dependency on binary chemical limit values.

Risk assessments of contaminated sediments from the perspective of weight of evidence strategies – a Swedish case study

Bruce, P.; Sobek, A.; Ohlson, Y.; Bradshaw, C.
2020 | Hum. Ecol. Risk Assess

Several countries currently lack common recommendations specific
to Ecological Risk Assessment (ERA) of contaminated sediments
and stakeholders report inconsistencies between currently used
approaches. The objective of this study was to provide an increased
understanding of how ERAs of contaminated sediments are conducted
in comparison to established guidelines. For this, we use
Sweden as a case study and compare seven ERAs with four internationally
established strategies. Our results indicate that contaminant
concentrations receive a comparatively high weight, despite a
lack of appropriate benchmarks; toxicity measurements are uncommon,
while routine in established strategies; and the integration and
interpretation of results lack transparency. We identify three areas
that may help improve the practice of ERAs: a common approach to
benchmarks, recommendations for how to assess toxic effects, and a
common approach for integrating and interpreting results.

Association between Aquatic Micropollutant Dissipation and River Sediment Bacterial Communities

Coll, C.; Bier, R.; Li, Z.; Langenheder, S.; Gorokhova, E.; Sobek, A.
2020 | Environ. Sci. Technol. | 54 (22) (14380-14392)

Organic contaminant mixture significantly changes microbenthic community structure and increases the expression of PAH degradation genes

Iburg, I.; Nybom, I.; Bonaglia, S.; Karlson, A.M.L.; Sobek, A.; Nascimento, F.J.A.
2020 | Front. Environ. Sci. | 8

Bacterial diversity controls transformation of wastewater-derived organic contaminants in river-simulating flumes

Posselt, M.; Mechelke, J.; Rutere, C.; Coll, C.; Jaeger, A.; Raza, M.; Meinikmann, K.; Krause, S.; Sobek, A.; Lewandowski, J.; Horn, M.A.; Hollender, J.; Benskin, J.P.
2020 | Environ. Sci. Technol.

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