Reduced European emissions of S and N--effects on air concentrations, deposition and soil water chemistry in Swedish forests

Changes in sulphur and nitrogen pollution in Swedish forests have been assessed in relation to European emission reductions, based on measurements in the Swedish Throughfall Monitoring Network. Measurements were analysed over 20 years with a focus on the 12-year period 1996 to 2008. Air concentrations of SO₂ and NO₂, have decreased. The SO₄-deposition has decreased in parallel with the European emission reductions. Soil water SO₄-concentrations have decreased at most sites but the pH, ANC and inorganic Al-concentrations indicated acidification recovery only at some of the sites. No changes in the bulk deposition of inorganic nitrogen could be demonstrated. Elevated NO₃-concentrations in the soil water occurred at irregular occasions at some southern sites. Despite considerable air pollution emission reductions in Europe, acidification recovery in Swedish forests soils is slow. Nitrogen deposition to Swedish forests continues at elevated levels that may lead to leaching of nitrate to surface waters.     

Governance of Complex Socio-Environmental Risks: The Case of Hazardous Chemicals in the Baltic Sea

Complex socio-environmental risks challenge society. In response to scientific uncertainty and socio-political controversies, environmental governance, precaution, and the ecosystem approach to management are held forward as complements to governmental risk-based sector-restricted regulation. We analyze this development for hazardous substances in the Baltic Sea. Based on interviews and policy analysis, we study informal governance and, in particular, four central EU and international policies, and investigate how present governance relates to risks and objectives at hand. While showing emergence of broader governance approaches, we conclude that central objectives will not likely be met. Furthermore, we question the quest for broad environmental governance and emphasize the value of command and control regulation, if it implements precaution. These findings contribute to the theorizing on environmental (risk) governance. Finally, we provide some ideas that could help development and implementation of risk policies for hazardous chemicals in the Baltic Sea as well as other complex risks.     

Structure-related distribution of PCDD/Fs, PCBs and HCB in a river-sea system

Water concentrations of PCDD/Fs, HCB, and non-ortho, mono-ortho, and non-dioxin-like PCBs were measured four times during 1 year in a coastal area of the Baltic Sea, to investigate background levels and distribution behaviour. Sampling sites included two rivers, an estuary, and the sea. Particulate and apparently dissolved concentrations were determined using active sampling (filters + PUFs), while freely dissolved concentrations were determined using passive sampling (POM-samplers). The distribution between particulate + colloidal and freely dissolved phases, in the form of TOC-normalized distribution ratios (K_TOC), was found to be near or at equilibrium. The observed K_TOC were not significantly different between sampling sites or seasons. For PCDD/Fs, the concentrations were significantly correlated to suspended particulate matter (SPM), while no correlation to organic carbon (TOC) was observed. In the estuary and the sea, PCB concentrations were correlated to TOC. The sorption of various congeners to SPM and TOC appeared to be related to both hydrophobicity and 3D-structure. The PCDD/F concentration in the sea decreased to one third in May, likely connected to the increased vertical flux of particles during the spring bloom.     

Risk assessments for forest trees: the performance of the ozone flux versus the AOT concepts

Published ozone exposure-response relationships from experimental studies with young trees performed at different sites across Europe were re-analysed in order to test the performance of ozone exposure indices based on AOTX (Accumulated exposure Over a Threshold of X nmol mol(-1)) and AF(st)Y (Accumulated Stomatal Flux above a threshold of Y nmol m(-2) s(-1)). AF(st)1.6 was superior, as compared to AOT40, for explaining biomass reductions, when ozone sensitive species with differing leaf morphology were included in the analysis, while this was not the case for less sensitive species. A re-analysis of data with young black cherry trees, subject to different irrigation regimes, indicated that leaf visible injuries were more strongly related to the estimated stomatal ozone uptake, as compared to the ozone concentration in the air. Experimental data with different clones of silver birch indicated that leaf thickness was also an important factor influencing the development of ozone induced leaf visible injury.     

Are individual NOEC levels safe for mixtures? A study on mixture toxicity of brominated flame-retardants in the copepod Nitocra spinipes

In aquatic ecosystems organisms are exposed to mixtures of pollutants. Still, risk assessment focuses almost exclusively on effect characterization of individual substances. The main objective of the current study was therefore to study mixture toxicity of a common group of industrial substances, i.e., brominated flame-retardants (BFRs), in the harpacticoid copepod Nitocra spinipes. Initially, 10 BFRs with high hydrophobicity but otherwise varying chemical characteristics were selected based on multivariate chemical characterization and tested individually for effects on mortality and development using a partial life cycle test (six days) where silica gel is used as a carrier of the hydrophobic substances. Based on these findings, six of the 10 BFRs were mixed in a series of NOEC proportions (which were set to 0.008, 0.04, 0.2, 1, and five times the NOEC concentrations for each individual BFR), loaded on silica gel and tested in a full life cycle test (26 days). Significantly increased mortality was observed in N. spinipes after six and 26 days exposure at a NOEC proportion that equals the NOEC LDR value (x1) for each BFR in the mixture (p=0.0015 and p=0.0105, respectively). At the NOECx5 proportion all animals were dead. None of the other NOEC proportions caused significant negative responses related to development and reproduction. This shows that low concentrations of individual substances can cause toxicity if exposed in mixtures, which highlights the need to consider mixture toxicity to a greater extent in regulatory work.     

Trampling impact on vegetation of embryonic and stabilised sand dunes in Montenegro

Trampling is one of the human activities that are harmful for plant species and communities of sand dune ecosystems. The aim of this study was to compare the vegetation of embryonic and shifting Ammophila sand dunes with and without fencing to limit trampling. Fenced sand dunes appeared to be richer in species but differences were more prominent in embryonic sand dunes. Some species (Cakile maritima, Pancratium maritimum) were missing on trampled embryonic dunes. The positive impact of trampling exclusion on embryonic sand dunes was indicated by a lowered slope in a Whittaker graph as well as by rarefaction curves that showed higher species richness on the lower slope. Changes in the vegetation of more stabilised shifting Ammophila sand dunes due to trampling are not evident, although species composition is also impoverished. Fencing of parts of sand dunes proved to be an effective measure for vegetation conservation. In addition to physical exclusion of visitors, fences can also have symbolic value for raising public awareness.     

Zero-valent iron particles for PCB degradation and an evaluation of their effects on bacteria,plants, and soil organisms

Two types of nano-scale zero-valent iron (nZVI-B prepared by borohydride reduction and nZVI-T produced by thermal reduction of iron oxide nanoparticles in H₂) and a micro-scale ZVI (mZVI) were compared for PCB degradation efficiency in water and soil. In addition, the ecotoxicity of nZVI-B and nZVI-T particles in treated water and soil was evaluated on bacteria, plants, earthworms, and ostracods. All types of nZVI and mZVI were highly efficient in degradation of PCBs in water, but had little degradation effect on PCBs in soil. Although nZVI-B had a significant negative impact on the organisms tested, treatment with nZVI-T showed no negative effect, probably due to surface passivation through controlled oxidation of the nanoparticles.

     

The sensitivity of current and future forest managers to climate-induced changes in ecological processes

Climate vulnerability of managed forest ecosystems is not only determined by ecological processes but also influenced by the adaptive capacity of forest managers. To better understand adaptive behaviour, we conducted a questionnaire study among current and future forest managers (i.e. active managers and forestry students) in Austria. We found widespread belief in climate change (94.7 % of respondents), and no significant difference between current and future managers. Based on intended responses to climate-induced ecosystem changes, we distinguished four groups: highly sensitive managers (27.7 %), those mainly sensitive to changes in growth and regeneration processes (46.7 %), managers primarily sensitive to regeneration changes (11.2 %), and insensitive managers (14.4 %). Experiences and beliefs with regard to disturbance-related tree mortality were found to particularly influence a manager’s sensitivity to climate change. Our findings underline the importance of the social dimension of climate change adaptation, and suggest potentially strong adaptive feedbacks between ecosystems and their managers.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-015-0737-6) contains supplementary material, which is available to authorized users.     

Spatially valid data of atmospheric deposition of heavy metals and nitrogen derived by moss surveys for pollution risk assessments of ecosystems

For analysing element input into ecosystems and associated risks due to atmospheric deposition, element concentrations in moss provide complementary and time-integrated data at high spatial resolution every 5 years since 1990. The paper reviews (1) minimum sample sizes needed for reliable, statistical estimation of mean values at four different spatial scales (European and national level as well as landscape-specific level covering Europe and single countries); (2) trends of heavy metal (HM) and nitrogen (N) concentrations in moss in Europe (1990–2010); (3) correlations between concentrations of HM in moss and soil specimens collected across Norway (1990–2010); and (4) canopy drip-induced site-specific variation of N concentration in moss sampled in seven European countries (1990–2013). While the minimum sample sizes on the European and national level were achieved without exception, for some ecological land classes and elements, the coverage with sampling sites should be improved. The decline in emission and subsequent atmospheric deposition of HM across Europe has resulted in decreasing HM concentrations in moss between 1990 and 2010. In contrast, hardly any changes were observed for N in moss between 2005, when N was included into the survey for the first time, and 2010. In Norway, both, the moss and the soil survey data sets, were correlated, indicating a decrease of HM concentrations in moss and soil. At the site level, the average N deposition inside of forests was almost three times higher than the average N deposition outside of forests.     

Neutralisation of an acidic pit lake by alkaline waste products

A former open pit where black shale (alum shale) was excavated during 1942–1965 has been water filled since 1966. The water chemistry was dominated by calcium and sulphate and had a pH of 3.2–3.4 until 1997–1998, when pH was gradually increasing. This was due to the intrusion of leachates from alkaline cement waste deposited close to the lake. A stable pH of around 7.5 was obtained after 6–7 years. The chemistry of the pit lake has changed due to the neutralisation. Concentrations of some dissolved metals, notably zinc and nickel, have gone down, as a result of adsorption/co-precipitation on solid phases (most likely iron and aluminium hydroxides), while other metals, notably uranium and molybdenum, are present at elevated levels. Uranium concentration is reaching a minimum of around pH 6.5 and is increasing at higher pH, which may indicate a formation of neutral and anionic uranyl carbonate species at high pH (and total carbonate levels around 1 mM). Weathering of the water-exposed shale is still in progress.