Seasonal nitrogen fluxes of the Lena River Delta

The Arctic is nutrient limited, particularly by nitrogen, and is impacted by anthropogenic global warming which occurs approximately twice as fast compared to the global average. Arctic warming intensifies thawing of permafrost-affected soils releasing their large organic nitrogen reservoir. This organic nitrogen reaches hydrological systems, is remineralized to reactive inorganic nitrogen, and is transported to the Arctic Ocean via large rivers. We estimate the load of nitrogen supplied from terrestrial sources into the Arctic Ocean by sampling in the Lena River and its Delta. We took water samples along one of the major deltaic channels in winter and summer in 2019 and sampling station in the central delta over a one-year cycle. Additionally, we investigate the potential release of reactive nitrogen, including nitrous oxide from soils in the Delta. We found that the Lena transported nitrogen as dissolved organic nitrogen to the coastal Arctic Ocean and that eroded soils are sources of reactive inorganic nitrogen such as ammonium and nitrate. The Lena and the Deltaic region apparently are considerable sources of nitrogen to nearshore coastal zone. The potential higher availability of inorganic nitrogen might be a source to enhance nitrous oxide emissions from terrestrial and aquatic sources to the atmosphere.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01665-0.     

10th anniversary review: when healthy food becomes polluted-implications for public health and dietary advice

Divergent scientific and regulatory agency perspectives about contaminants in fish have lead to contradictory advice and confusing public messages about its consumption. The evidence for the protective effect of eating fish on cardiovascular outcomes is considered to be convincing. It has long been attributed to n-3 unsaturated long-chain fatty acids. Persistent organic pollutants (POPs) are compounds that are lipid soluble and accumulate in the aquatic food chain. Despite a considerable decrease in their levels in fish during the last two decades, there is still significant concern about potential negative health effects and an ongoing debate exists about what type of fish consumption advisories are most suitable. In this review our aim is twofold, namely to explore: (1) the underlying causes for the conflicting recommendations by discussing the strengths and limitations of risk assessment and epidemiological evidence; and (2), the role of risk management in formulating public dietary advisories. It is our view that the latter advice is most appropriately formulated in the context of risk management, of which both epidemiologic evidence and risk assessment are essential components.     

A method for quick assessment of CO2 storage capacity in closed and semi-closed saline formations

Saline aquifers of high permeability bounded by overlying/underlying seals may be surrounded laterally by low-permeability zones, possibly caused by natural heterogeneity and/or faulting. Carbon dioxide (CO₂) injection into and storage in such “closed” systems with impervious seals, or “semi-closed” systems with non-ideal (low permeability) seals, is different from that in “open” systems, from which the displaced brine can easily escape laterally. In closed or semi-closed systems, the pressure buildup caused by continuous industrial-scale CO₂ injection may have a limiting effect on CO₂ storage capacity, because geomechanical damage caused by overpressure needs to be avoided. In this research, a simple analytical method was developed for the quick assessment of the CO₂ storage capacity in such closed and semi-closed systems. This quick-assessment method is based on the fact that native brine (of an equivalent volume) displaced by the cumulative injected CO₂ occupies additional pore volume within the storage formation and the seals, provided by pore and brine compressibility in response to pressure buildup. With non-ideal seals, brine may also leak through the seals into overlying/underlying formations. The quick-assessment method calculates these brine displacement contributions in response to an estimated average pressure buildup in the storage reservoir. The CO₂ storage capacity and the transient domain-averaged pressure buildup estimated through the quick-assessment method were compared with the “true” values obtained using detailed numerical simulations of CO₂ and brine transport in a two-dimensional radial system. The good agreement indicates that the proposed method can produce reasonable approximations for storage–formation–seal systems of various geometric and hydrogeological properties.     

Conceptual development of a harmonised method for tracking change and evaluating policy in the agri-environment: The Agri-environmental Footprint Index

An aggregated farm-level index, the Agri-environmental Footprint Index (AFI), based on multiple criteria methods and representing a harmonised approach to evaluation of EU agri-environmental schemes is described. The Index uses a common framework for the design and evaluation of policy that can be customised to locally relevant agri-environmental issues and circumstances. Evaluation can be strictly policy-focused, or broader and more holistic in that context-relevant assessment criteria that are not necessarily considered in the evaluated policy can nevertheless be incorporated. The Index structure is flexible, and can respond to diverse local needs. The process of Index construction is interactive, engaging farmers and other relevant stakeholders in a transparent decision-making process that can ensure acceptance of the outcome, help to forge an improved understanding of local agri-environmental priorities and potentially increase awareness of the critical role of farmers in environmental management. The structure of the AFI facilitates post-evaluation analysis of relative performance in different dimensions of the agri-environment, permitting identification of current strengths and weaknesses, and enabling future improvement in policy design. Quantification of the environmental impact of agriculture beyond the stated aims of policy using an ‘unweighted’ form of the AFI has potential as the basis of an ongoing system of environmental audit within a specified agricultural context.     

Relationship between the position preference and nutritional state of individuals in schools of juvenile roach (Rutilus rutilus)

Summary Position preferences of well-fed and food-deprived juvenile roach were investigated in schools of 2 and 4 fish in the laboratory. Food-deprived fish appeared significantly more often in the front position than their well-fed conspecifics. For fish at the same hunger level, individuals at the front of the school had the highest feeding rate. These results represent the first evidence for a relationship between the nutritional state of individual fish and their positions in a school and suggest a functional advantage of the preference. Offprint requests to: J. Krause at the present address     

Relationships Between Macroinvertebrate Assemblages of Stony Littoral Habitats and Water Chemistry Variables Indicative of Acid-stress

Gradient analyses were used to correlatively determine the importance of acid-related variables for littoral macroinvertebrate assemblages. To better ascertain the effects of acidity on macroinvertebrate assemblages we removed sites judged to be affected by other stressors such as agriculture, urbanization and liming. PCA of land use and water chemistry confirmed the presence of an acidity gradient; several acidity variables (e.g. pH and buffering capacity) were strongly correlated with the first PC axis, which explained Ca 32% of the variance in the environmental data. Partial constrained ordination of littoral macroinvertebrate assemblages with water chemistry, after removing the effect of other confounding variables (e.g. land use/type), showed that acidity variables accounted for significant amounts of among-lake variability in assemblage structure. Regression of canonical scores (a metric of community composition) and diversity with pH and alkalinity was used to visually determine ecological breakpoints or threshold values. Five classes were established for pH: pH?<?5 (extremely acid), 5?<?pH?≤?5.6 (very acid), 5.6?<?pH?≤?6.2 (acid), 6.2?<?pH?≤?6.8 (weakly acid) and pH?>?6.8 (neutral-alkaline). Similarly, three classes were determined for alkalinity/acidity: <0.02, 0.02–0.1 and >0.1 meq/L.     

Environmental assessment of solid waste systems and technologies: EASEWASTE.

A new model has been developed for evaluating the overall resource consumption and environmental impacts of municipal solid waste management systems by the use of life cycle assessment. The model is named EASEWASTE (Environmental Assessment of Solid Waste Systems and Technologies) and is able to compare different waste management strategies, waste treatment methods and waste process technologies. The potential environmental impacts can be traced back to the most important processes and waste fractions that contribute to the relevant impacts. A model like EASEWASTE can be used by waste planners to optimize current waste management systems with respect to environmental achievements and by authorities to set guidelines and regulations and to evaluate different strategies for handling of waste. The waste hierarchy has for decades been governing waste management but the ranking of handling approaches may not always be the most environmentally friendly. The EASEWASTE model can identify the most environmentally sustainable solution, which may differ among waste materials and regions and can add valuable information about environmental achievements from each process in a solid waste management system.     

Method for determination of methane potentials of solid organic waste

A laboratory procedure is described for measuring methane potentials of organic solid waste. Triplicate reactors with 10 grams of volatile solids were incubated at 55 degrees C with 400 ml of inoculum from a thermophilic biogas plant and the methane production was followed over a 50-day period by regular measurements of methane on a gas chromatograph. The procedure involves blanks as well as cellulose controls. Methane potentials have been measured for source-separated organic household waste and for individual waste materials. The procedure has been evaluated regarding practicality, workload, detection limit, repeatability and reproducibility as well as quality control procedures. For the source-separated organic household waste a methane potential of 495 ml CH4/g VS was found. For fat and oil a lag-phase of several days was seen. The protein sample was clearly inhibited and the maximal methane potential was therefore not achieved. For paper bags, starch and glucose 63, 84 and 94% of the theoretical methane potential was achieved respectively. A detection limit of 72.5 ml CH4/g VS was calculated from the results. This is acceptable, since the methane potential of the tested waste materials was in the range of 200-500 ml CH4/g VS. The determination of methane potentials is a biological method subject to relatively large variation due to the use of non-standardized inoculum and waste heterogeneity. Therefore, procedures for addressing repeatability and reproducibility are suggested.     

Sectoral marginal abatement cost curves: implications for mitigation pledges and air pollution co-benefits for Annex I countries

Using the GAINS (Greenhouse Gas–Air Pollution Interactions and Synergies) model, we derived Annex I marginal abatement cost curves for the years 2020 and 2030 for three World Energy Outlook baseline scenarios (2007–2009) of the International Energy Agency. These cost curves are presented by country, by greenhouse gas and by sector. They are available for further inter-country comparisons in the GAINS Mitigation Efforts Calculator—a free online tool. We illustrate the influence of the baseline scenario on the shape of mitigation cost curves, and identify key low cost options as well as no-regret priority investment areas for the years 2010–2030. Finally, we show the co-effect of GHG mitigation on the emissions of local air pollutants and argue that these co-benefits offer strong local incentives for mitigation.