Mitigation of methane emission from Fakse landfill using a biowindow system

Landfills are significant sources of atmospheric methane (CH₄) that contributes to climate change, and therefore there is a need to reduce CH₄ emissions from landfills. A promising cost efficient technology is to integrate compost into landfill covers (so-called “biocovers”) to enhance biological oxidation of CH₄. A full scale biocover system to reduce CH₄ emissions was installed at Fakse landfill, Denmark using composted yard waste as active material supporting CH₄ oxidation. Ten biowindows with a total area of 5000 m² were integrated into the existing cover at the 12 ha site. To increase CH₄ load to the biowindows, leachate wells were capped, and clay was added to slopes at the site. Point measurements using flux chambers suggested in most cases that almost all CH₄ was oxidized, but more detailed studies on emissions from the site after installation of the biocover as well as measurements of total CH₄ emissions showed that a significant portion of the emission quantified in the baseline study continued unabated from the site. Total emission measurements suggested a reduction in CH₄ emission of approximately 28% at the end of the one year monitoring period. This was supported by analysis of stable carbon isotopes which showed an increase in oxidation efficiency from 16% to 41%. The project documented that integrating approaches such a whole landfill emission measurements using tracer techniques or stable carbon isotope measurements of ambient air samples are needed to document CH₄ mitigation efficiencies of biocover systems. The study also revealed that there still exist several challenges to better optimize the functionality. The most important challenges are to control gas flow and evenly distribute the gas into the biocovers.     

Promise and performance of agricultural nutrient management policy: Lessons from the Baltic Sea

Following decades of international collaboration to restore the Baltic Sea, we provide an assessment of the domestic implementation of measures agreed to limit diffuse agricultural pollution and the patterns of policy instruments applied. Despite the Helsinki Convention being unusually specific in detailing what measures countries should introduce, we find many shortcomings. These are most pronounced in the larger countries (Poland, Germany and Russia), while smaller countries perform better, notably Sweden and Estonia. The patterns of policy instruments applied differ, influenced by domestic politics. The limited use of complementary policy instruments suggests that other priorities overrule full and effective implementation, with engagement mirroring the advantages that a restored Baltic Sea can bring to countries. Using the European Agricultural Fund for Rural Development to support farmers in managing nutrients, particularly advisory services and investments in modern manure management technologies, represents a significant opportunity for reducing agricultural pollution in most countries.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01549-3.     

Safety in construction – a comprehensive description of the characteristics of high safety standards in construction work, from the combined perspective of supervisors and experienced workers

Introduction

The often applied engineering approach to safety management in the construction industry needs to be supplemented by organizational measures and measures based on how people conceive and react to their social environment. This requires in-depth knowledge of the broad preconditions for high safety standards in construction. The aim of the study was to comprehensively describe the preconditions and components of high safety standards in the construction industry from the perspective of both experienced construction workers and first-line managers.

Method

Five worker safety representatives and 19 first-line managers were interviewed, all strategically selected from within a large Swedish construction project. Phenomenographic methodology was used for data acquisition and analysis and to categorize the information. Nine informants verified the results.

Results

The study identified four main categories of work safety preconditions and components: (1) Project characteristics and nature of the work, which set the limits of safety management; (2) Organization and structures, with the subcategories planning, work roles, procedures, and resources; (3) Collective values, norms, and behaviors, with the subcategories climate and culture, and interaction and cooperation; and (4) Individual competence and attitudes, with the subcategories knowledge, ability and experience, and individual attitudes.

Discussion

The results comprehensively describe high safety standards in construction, incorporating organizational, group, individual, and technical aspects. High-quality interaction between different organizational functions and hierarchical levels stood out as important aspects of safety. The results are discussed in relation to previous research into safety and into the social-psychological preconditions for other desired outcomes in occupational settings.

Impact on Industry

The results can guide construction companies in planning and executing construction projects to a high safety standard.     

Bioaccumulation and lack of oxidative stress response in the ragworm H. diversicolor following exposure to Ra in sediment

The main effluent from oil and gas production, produced water, from some platforms in the North Sea contains elevated concentrations of ²²⁶Ra. The aim of this study was to investigate whether ²²⁶Ra in sediment would accumulate in and affect sediment-dwelling organisms. In addition, we wanted to determine if the bioavailability would be modulated by the presence of a scale inhibitor which is used during oil and gas production. Hediste diversicolor was therefore exposed to different levels of ²²⁶Ra (30–6600 Bq kg⁻¹) in combination with scale inhibitor in the sediments in a flow through system. The levels of radioactivity in the exposures were close to levels that can be measured in proximity to oil/gas production facilities. ²²⁶Ra spiked to natural sediment partitioned into pore water and accumulated in the sediment-dwelling polychaete following a four-week exposure period. The results suggest that ²²⁶Ra did not bind strongly to sediment (low sediment:water partitioning coefficient), but it was not shown to bioaccumulate in any great extent (bioaccumulation factors of 0.019–0.022). Exposure of H. diversicolor in sediments with up to 6600 Bq kg⁻¹²²⁶Ra had no measurable effect on the total oxyradical scavenging capacity of the organisms compared to control. So although they accumulated the alpha-emitter, the treatments did not appear to cause oxidative stress in polychaete tissues.     

Improving Oxygen Conditions in the Deeper Parts of Bornholm Sea by Pumped Injection of Winter Water

Vertical diffusivity and oxygen consumption in the basin water, the water below the sill level at about 59 m depth, have been estimated by applying budget methods to monitoring data from hydrographical stations BY4 and BY5 for periods without water renewal. From the vertical diffusivity, the mean rate of work against the buoyancy forces below 65 m depth is estimated to about 0.10 mW m⁻². This is slightly higher than published values for East Gotland Sea. The horizontally averaged vertical diffusivity κ can be approximated by the expression κ = a₀N⁻¹ where N is the buoyancy frequency and a₀ ≈ 1.25 × 10⁻⁷ m² s⁻², which is similar to values for a₀ used for depths below the halocline in Baltic proper circulation models for long-term simulations. The contemporary mean rate of oxygen consumption in the basin water is about 75 g O₂ m⁻² year⁻¹, which corresponds to an oxidation of 28 g C m⁻² year⁻¹. The oxygen consumption in the Bornholm Basin doubled from the 1970s to the 2000s, which qualitatively explains the observed increasing frequency and vertical extent of anoxia and hypoxia in the basin water in records from the end of the 1950s to present time. A horizontally averaged vertical advection–diffusion model of the basin water is used to calculate the effects on stratification and oxygen concentration by a forced pump-driven vertical convection. It is shown that the residence time of the basin water may be reduced by pumping down and mixing the so-called winter water into the deepwater. With the present rate of oxygen consumption, a pumped flux of about 25 km³ year⁻¹ would be sufficient to keep the oxygen concentration in the deepwater above 2 mL O₂ L⁻¹.     

Ecology,evolution, and management strategies of northern pike populations in the Baltic Sea

Baltic Sea populations of the northern pike (Esox lucius) have declined since the 1990s, and they face additional challenges due to ongoing climate change. Pike in the Baltic Sea spawn either in coastal bays or in freshwater streams and wetlands. Pike recruited in freshwater have been found to make up about 50 % of coastal pike stocks and to show natal homing, thus limiting gene flow among closely located spawning sites. Due to natal homing, sub-populations appear to be locally adapted to their freshwater recruitment environments. Management actions should therefore not involve mixing of individuals originating from different sub-populations. We offer two suggestions complying with this advice: (i) productivity of extant freshwater spawning populations can be boosted by modifying wetlands such that they promote spawning and recruitment; and (ii) new sub-populations that spawn in brackish water can potentially be created by transferring fry and imprinting them on seemingly suitable spawning environments.     

Polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD) in seven different marine bird species from Iceland

Data on distribution, concentration and trends of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs) is scarce in biota from the sub-Arctic region of the Atlantic. The present study is an investigation on PBDE and HBCD concentrations in eggs from seven marine bird species from Iceland, i.e. common eider (Somateria mollissima), arctic tern (Sterna paradisaea), guillemot (Uria aalge), fulmar (Fulmarus glacialis), lesser black-backed gull (Larus fuscus), great black-backed gull (Larus marinus) and great skua (Stercorarius skua). Concentrations of sum PBDEs ranged from 44 ng g⁻¹ fat in eider eggs to 2400 ng g⁻¹ fat in great skua eggs. The contribution of different PBDE congeners to the sum concentration differed between species. Concentration of HBCDs (sum of α−,β⁻ and γ−HBCD) ranged from 1.3 ng g⁻¹ fat in arctic tern eggs to 41 ng g⁻¹ fat in great black-backed gull. PCA on PBDE and HBCD shows different trends between the two BFR groups, further indicating different sources/usage. Investigations on any potential health or population effects of environmental pollutants on the great skua are advised since both the PBDE and HBCD concentrations are high.     

Chemisorption of hydrogen sulphide and methanethiol by light expanded clay aggregates (Leca)

Removal of volatile sulphur compounds from livestock waste air by biological air filtration may be enhanced by application of packing materials with reactive properties. In this study, light expanded clay aggregates (Leca®) was tested with respect to sorption and potential chemical degradation of H₂S, Methanethiol (MT) and Dimethyl sulphide (DMS). Leca was selected due to its content of minerals, including iron, and due to its high specific surface area. The performance of Leca was evaluated based on breakthrough curves and by comparing the difference between the inlet and outlet gas concentrations. Whereas DMS did not appear to be removed by Leca, both H₂S and MT were removed with variable efficiency depending on the specific conditions. Dimethyl disulphide (DMDS) and dimethyl trisulphide (DMTS) were demonstrated to be produced during the degradation process in relatively high yields. A comparison between ambient air and nitrogen gas conditions showed that the chemisorption of H₂S and MT did not necessarily need oxygen to be present. X-ray analysis of Leca showed an abundance of Fe₂O₃. It is therefore hypothesized that Fe₂O₃ in Leca can remove H₂S and MT by chemisorption. Both air velocity and moisture content clearly affected the capacity of Leca for removal of H₂S and MT. Lower removal is seen at higher air velocities, whereas higher moisture content enhances removal. However, chemisorption of MT by Leca appears to be limited above a threshold moisture level. Potential reaction mechanisms are discussed in relation to the observed effects. The results implicate that Leca can be used as a filter material with reactive properties provided that moisture content is controlled and that an adequate air velocity is used.     

High prevalence of infections and pathological changes in burbot (Lota lota) from a polluted lake (Lake Mjøsa,Norway)

The aim of the present study was to investigate whether exposure to high levels of persistent organic pollutants (POPs) affected a fish population in Lake Mjøsa. Lake Mjøsa is known to be contaminated by polybrominated diphenyl ethers (PBDEs), a subgroup of brominated flame retardants from local industrial activities. Fish from Lake Losna, a less contaminated lake located close to Lake Mjøsa, was used as reference (control).The sampling of burbot (Lota lota) was carried out between 2005 and 2008. Hepatic levels of POPs were analysed in burbot from the two lakes, and the fish were examined for bacterial- and parasite infection and histopathological changes. The levels of polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs), and PBDEs were about 10, 15 and 300 times higher in fish from Lake Mjøsa compared to fish from Lake Losna. Mycobacterium salmoniphilum was present in 7% and 35% of the fish from Lake Losna and Lake Mjøsa respectively. Significantly higher number of external and visceral macroscopic lesions, histopathological diffuse changes and granulomas were seen in fish from Lake Mjøsa compared to Lake Losna. Furthermore the parasite infection was higher and the hepatic lipid content was significantly lower in burbot from Lake Mjøsa. The results of the present study suggest that the high level of contamination in Lake Mjøsa could have a negative impact on the health status of wild fish inhabiting the lake.     

Linking Cellulose Fiber Sediment Methyl Mercury Levels to Organic Matter Decay and Major Element Composition

Methylation of mercury (Hg) to highly toxic methyl Hg (MeHg), a process known to occur when organic matter (OM) decomposition leads to anoxia, is considered a worldwide threat to aquatic ecosystems and human health. We measured temporal and spatial variations in sediment MeHg, total Hg (THg), and major elements in a freshwater lagoon in Sweden polluted with Hg-laden cellulose fibers. Fiber decomposition, confined to a narrow surface layer, resulted in loss of carbon (C), uptake of nitrogen (N), phosphorus (P), and sulfur (S), and increased MeHg levels. Notably, fiber decomposition and subsequent erosion of fiber residues will cause buried contaminants to gradually come closer to the sediment–water interface. At an adjacent site where decomposed fiber accumulated, there was a gain in C and a loss of S when MeHg increased. As evidenced by correlation patterns and vertical chemical profiles, reduced S may have fueled C-fixation and Hg methylation at this site.