How oxygen deficiency in the Baltic Sea proper has spread and worsened: The role of ammonium and hydrogen sulphide

Even large inflows of oxygen-rich seawater to the Baltic Proper have in recent decades given only short-lived relief from oxygen deficiency below the halocline. We analyse long-term changes in oxygen deficiency, and calculate the “total oxygen debt” ΣOD, the oxygen required to oxidize the hydrogen sulphide (H₂S) and ammonium (NH₄) that builds up during stagnation periods. Since the early 1990s, oxygen below 65m has gradually decreased during successive stagnation periods, and the ΣOD has increased, with NH₄ more important than previously recognised. After the major inflow in 2014, the Baltic Proper ΣOD has reached its highest level so far. The gradual shift of the ΣOD to shallower sub-halocline waters in the western and northern basins has increased the risk of periodic coastal hypoxia and export of hypoxic water to the Bothnian Sea. The potential for inflows large enough to more than eliminate the ΣOD seems limited in the near term.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-022-01738-8.     

Waste disposal and the recommendations of the International Commission on Radiological Protection – Challenges for radioecology and environmental radiation protection

The 2007 Recommendations of the International Commission on Radiological Protection (ICRP) represent a change from a process-based to an exposure-based approach, where exposure situations are categorised as planned, emergency, and existing exposure situations. Although the new Recommendations contain further changes based on, inter alia, scientific developments since the publication of the 1990 Recommendations, they overall represent more continuity than change – a notable exception being the direct consideration of environmental protection. The implications of the new Recommendations for radioactive waste management are fairly marginal, as earlier recommendations in this area are still considered valid. This communication provides a brief overview of the current ICRP system for radiological protection as applied to radioactive waste management, as well as an outlook including the possibility of using the developing ICRP system for management of environmental effects as an ‘alternative way of reasoning’ when building the safety case for a specific waste disposal concept.     

The effect of different holding conditions for environmental monitoring with caged rainbow trout (Oncorhynchus mykiss)

Biomarkers in fish can be a useful tool for environmental monitoring of aquatic ecosystems when diffuse pollution is becoming more important and new chemicals are being created continuously. There are, however, a number of drawbacks with this method. Because of environmental variability, health status of wild fish populations may differ between years, leading to unrepresentative results in long term studies. Furthermore, genetic or adaptive differences between populations complicate the interpretation of studies on different sites. The use of farmed fish, placed in cages, can reduce these problems. However, experimental conditions are likely to differ between sites. For practical reasons it may, e.g., be neccesary to use different types of caging. Here, the use of net cages and flow through tanks has been compared for a number of biomarkers. Rainbow trout (Oncorhynchus mykiss) were placed in net cages and flow through tanks in the river G?ta Alv, in western Sweden, during three different periods in 2004 and 2005. No differences between types of caging were found for any biomarker. Therefore, the results suggest that net cages and flow through tanks can be used and compared in environmental monitoring using biomarkers in caged rainbow trout. However, efforts should be taken to reduce differences in experimental conditions, e.g., light intensity and feeding levels.     

Sulfur recirculation for increased electricity production in Waste-to-Energy plants

Sulfur recirculation is a new technology for reducing boiler corrosion and dioxin formation. It was demonstrated in full-scale tests at a Waste to Energy plant in Göteborg (Sweden) during nearly two months of operation. Sulfur was recirculated as sulfuric acid from the flue gas cleaning back to the boiler, thus creating a sulfur loop.The new technology was evaluated by extensive measurement campaigns during operation under normal conditions (reference case) and operation with sulfur recirculation. The chlorine content of both fly ash and boiler ash decreased and the sulfur content increased during the sulfur recirculation tests. The deposit growth and the particle concentration decreased with sulfur recirculation and the dioxin concentration (I-TEQ) of the flue gas was reduced by approximately 25%. Sulfuric acid dew point measurements showed that the sulfuric acid dosage did not lead to elevated SO₃ concentrations, which may otherwise induce low temperature corrosion.In the sulfur recirculation corrosion probe exposures, the corrosion rate decreased for all tested materials (16Mo3, Sanicro 28 and Inconel 625) and material temperatures (450 °C and 525 °C) compared to the reference exposure. The corrosion rates were reduced by 60–90%. Sulfur recirculation prevented the formation of transition metal chlorides at the metal/oxide interface, formation of chromate and reduced the presence of zinc in the corrosion products. Furthermore, measured corrosion rates at 525 °C with sulfur recirculation in operation were similar or lower compared to those measured at 450 °C material temperature in reference conditions, which corresponds to normal operation at normal steam temperatures. This implies that sulfur recirculation allows for higher steam data and electricity production without increasing corrosion.     

Atmospheric deposition, retention, and stream export of dioxins and PCBs in a pristine boreal catchment

The mass-balance between diffuse atmospheric deposition of organic pollutants, amount of pollutants retained by the terrestrial environment, and levels of pollutants released to surface stream waters was studied in a pristine northern boreal catchment. This was done by comparing the input of atmospheric deposition of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) and PCBs with the amounts exported to surface waters. Two types of deposition samplers were used, equipped with a glass fibre thimble and an Amberlite sampler respectively. The measured fluxes showed clear seasonality, with most of the input and export occurring during winter and spring flood, respectively. The mass balance calculations indicates that the boreal landscape is an effective sink for PCDD/Fs and PCBs, as 96.0-99.9 % of received bulk deposition was retained, suggesting that organic pollutants will continue to impact stream water in the region for an extended period of time.     

Conceptual design of an integrated heating system at LKAB Malmberget with consideration of social-environmental damage costs

LKAB Malmberget is a Swedish mining site located at Malmberget, Sweden. Seven boiler centers are located in the north part of Malmberget. There are no connections in between these boiler centers, meaning that it is a decentralized heating system. The heat generated is used to heat up buildings and for mine ventilation air mainly during the cold periods. The heat is mainly provided from electric and oil boilers. However, most boilers under use are over 20 years old, and it is time to retrofit the boiler system and infrastructure. The purpose of this work is to design and optimize the heating system by introducing an integrated concept to minimize the heat production cost.An optimization model based on the mixed integer linear programming (MILP) has been developed. Several technical options have been considered in a new centralized heating system. The optimization principle is based on two kinds of perspectives: current price and external costs. With consideration of environmental and health damage from society concerns point of view, instead of environmental taxes in the current price perspective, the monetary values of externalities due to pollutants such as CO₂, NO_x, SO₂ and particulates emitted from the heating system are included. On the basis of data input and assumptions, modeling results indicate that a lower cost could be achieved when a waste heat recovery boiler is installed at the older pelletization plant to recover sensible heat from flue gas. This technical option is the best solution or at least contributes to the best solution in all optimization results. Including the externality cost is useful for making fair evaluation of the social-environmental impacts of the alternatives.     

欧洲地表酸化水体恢复--未来展望

到目前为止,有关欧洲地表酸化水体大范围化学恢复的文献层出不穷,而有关生物恢复的报道并不多见.建立在现今欧洲排放减少计划之上的模型研究表明,化学恢复仍将继续.而影响恢复进程的诸多不确定性因素主要包括:未来生态系统内氮的可能行为和气候变化的影响.下列4个与气候变化相关的因子可能对未来恢复进程产生影响:①海水盐分入侵事件爆发频率和强度增加;②干旱发生频率和强度上升;③有机碳交换周期加快;④硝化作用增强.目前降低水体酸化程度的国际性协作是成功的,但是未来还有大量问题需要解决,也会遇到许多困难.对未来硫、氮排放减少后以及气候变化背景下酸化地表水体的水化学和水生生物变化需要继续监测.     

Microbial secondary metabolites in school buildings inspected for moisture damage in Finland, The Netherlands and Spain

Secondary metabolites produced by fungi and bacteria are among the potential agents that contribute to adverse health effects observed in occupants of buildings affected by moisture damage, dampness and associated microbial growth. However, few attempts have been made to assess the occurrence of these compounds in relation to moisture damage and dampness in buildings. This study conducted in the context of the HITEA project (Health Effects of Indoor Pollutants: Integrating microbial, toxicological and epidemiological approaches) aimed at providing systematic information on the prevalence of microbial secondary metabolites in a large number of school buildings in three European countries, considering both buildings with and without moisture damage and/or dampness observations. In order to address the multitude and diversity of secondary metabolites a large number of more than 180 analytes was targeted in settled dust and surface swab samples using liquid chromatography/mass spectrometry (LC/MS) based methodology. While 42%, 58% and 44% of all samples collected in Spanish, Dutch and Finnish schools, respectively, were positive for at least one of the metabolites analyzed, frequency of detection for the individual microbial secondary metabolites - with the exceptions of emodin, certain enniatins and physcion - was low, typically in the range of and below 10% of positive samples. In total, 30 different fungal and bacterial secondary metabolites were found in the samples. Some differences in the metabolite profiles were observed between countries and between index and reference school buildings. A major finding in this study was that settled dust derived from moisture damaged, damp schools contained larger numbers of microbial secondary metabolites at higher levels compared to respective dust samples from schools not affected by moisture damage and dampness. This observation was true for schools in each of the three countries, but became statistically significant only when combining schools from all countries and thus increasing the sample number in the statistical analyses.     

Persistent organic pollutants (POP) in a benthic omnivore--a comparison between lake and stream crayfish populations

We investigated the accumulation of PCB and DDT in crayfish populations in 10 streams in southern Sweden. The results were compared with an earlier study on crayfish in lakes from the same area. We found that the concentration of pollutants in crayfish did not differ between the two types of systems. Variation in body burden was higher in stream living crayfish probably because of the higher influence from pollutants deposited in the catchment area and the more dynamic transport in streams. In streams, p,p'-DDE concentrations were positively correlated to trophic status (total phosphorous) while PCB did not show any correlation with the nutrient regime. Further, mean SigmaPCB and p,p'-DDE concentrations in crayfish did not correlate in streams. We suggest that the sources of the two pollutants differ for stream living crayfish. The results indicate that crayfish in streams are affected to a higher degree to pollutants in the catchment area and the precipitation regime. In lakes, internal processes govern uptake of pollutants in crayfish.