Temporal change estimation of mercury concentrations in northern pike (Esox lucius L.) in Swedish lakes

Adequate temporal trend analysis of mercury (Hg) in freshwater ecosystems is critical to evaluate if actions from the human society have affected Hg concentrations ([Hg]) in fresh water biota. This study examined temporal change in [Hg] in Northern pike (Esox lucius L.) in Swedish freshwater lakes between 1994 and 2006. To achieve this were lake-specific, multiple-linear-regression models used to estimate pike [Hg], including indicator variables representing time and fish weight and their interactions. This approach permitted estimation of the direction and magnitude of temporal changes in 25 lakes selected from the Swedish national database on Hg in freshwater biota. A significant increase was found in 36% of the studied lakes with an average increase in pike [Hg] of 3.7 ± 6.7% per year that was found to be positively correlated with total organic carbon. For lakes with a significant temporal change the dataset was based on a mean of 30 fish, while for lakes with no temporal change it was based on a mean of 13 fish.     

Comparison of organohalogen compounds in a white-tailed sea eagle egg laid in 1941 with five eggs from 1996 to 2001

Eggs laid by white-tailed sea eagles (Haliaeetus albicilla), one in 1941 and five eggs between 1996 and 2001, all from the same geographical region of the Baltic Sea, were screened for organohalogen substances. The 1941 egg contained hexachlorobenzene (HCB), but did not contain either of the pesticides hexachlorocyclohexane (HCH) or p,p′-DDT, nor any metabolites of the latter. In contrast, the more recent eggs (REs) contained all of these compounds. Of the seven polychlorinated biphenyls (PCBs) analyzed (CB28, −52, −101, −118, −138/−163, −153 and 180), only the more highly chlorinated congeners were detected in the 1941 sample, with CB153 followed by CB180 showing the highest concentrations. All eggs demonstrated the same congener pattern with respect to the more highly chlorinated PCBs, but concentrations were approximately 70-230 times higher in the REs. All of the polychlorinated-p-dioxin and dibenzofuran (PCDD/Fs) congeners analyzed were detected in the eggs, with the dominant congener being 2,3,4,7,8-PeCDF (1250 pg/g l.w. in 1941 and 1540 pg/g l.w. (GM) for the REs, respectively). None of the other congeners exceeded 400 pg/g l.w., and the concentrations of 2,3,7,8-TCDD, 2,3,7,8-TCDF and 1,2,3,7,8-PeCDF were all lower in the REs. None of five congeners of polybrominated diphenyl ethers (PBDEs) found in the REs was detected in the egg from 1941. The three methoxylated brominated diphenyl ethers (MeO-BDEs) analyzed were found at similar levels and with a similar congener pattern in REs as in the egg from 1941.In conclusion, this study has shown the absence of DDE and PBDE and the presence of HCB and PCBs in a white-tailed sea eagle egg laid in 1941, and a strong increase of PCBs, DDE and PBDE in white-tailed sea eagle eggs from the same area in 1996-2001. The MeO-BDEs were found in similar concentrations in the analyzed eggs. The 1941 sample shows substantial concentrations of PCDD/Fs, noteworthy in the same magnitude as in the recent samples, illustrating the historical and recent exposure of these compounds.     

Sodium borohydride reduction of individual polybrominated diphenyl ethers

Many chemicals in use today lack appropriate documentation on their environmental properties, fate, and effects. To counteract this lack of documentation it is vital to thoroughly investigate a compound’s fate in the environment before it comes into use. The present study is describing a novel method for assessing the reduction potential of polybrominated diphenyl ethers (PBDEs), as a part of a project aimed to create an experimental model for determination of chemical persistence. The reductive transformation of 15 PBDE congeners using sodium borohydride was determined. Pseudo-first-order reaction rate constants of the transformations were determined by monitoring the disappearance of the investigated congeners. The reductions lead primarily to formation of lower brominated PBDEs. Each PBDE congener was tested in a total of ten replicates which showed a relative standard deviation of 31% or less. The decaBDE, BDE-209 was approximately 3 times as prone to reductive transformation as BDE-207. The three nonaBDEs, BDE-206, BDE-207, and BDE-208, showed similar reductive potential. The reactivity of the tested octaBDEs was quite variable, from 5% to 24% of the reactivity of BDE-209 for BDE-196 and BDE-198, respectively. The heptaBDEs studied were in the range of the less reactive octaBDEs, except for BDE-181 which was as high as 13% of the reactivity of BDE-209. The results presented give a method for measuring the propensity of PBDEs, and possibly similar compounds, to undergo reductions. They indicate a potential route to a vital piece of information in the assessment of environmental persistence of chemicals.     

Comparison of techniques for estimating PAH bioavailability: uptake in Eisenia fetida, passive samplers and leaching using various solvents and additives

The aim of this study was to evaluate different techniques for assessing the availability of polycyclic aromatic hydrocarbons (PAHs) in soil. This was done by comparing the amounts (total and relative) taken up by the earthworm Eisenia fetida with the amounts extracted by solid-phase microextraction (SPME), semi-permeable membrane devices (SPMDs), leaching with various solvent mixtures, leaching using additives, and sequential leaching. Bioconcentration factors of PAHs in the earthworms based on equilibrium partitioning theory resulted in poor correlations to observed values. This was most notable for PAHs with high concentrations in the studied soil. Evaluation by principal component analysis (PCA) showed distinct differences between the evaluated techniques and, generally, there were larger proportions of carcinogenic PAHs (4-6 fused rings) in the earthworms. These results suggest that it may be difficult to develop a chemical method that is capable of mimicking biological uptake, and thus estimating the bioavailability of PAHs.     

Role of sea-ice biota in nutrient and organic material cycles in the northern Baltic Sea

This paper compiles biological and chemical sea-ice data from three areas of the Baltic Sea: the Bothnian Bay (Hailuoto, Finland), the Bothnian Sea (Norrby, Sweden), and the Gulf of Finland (Tv?rminne, Finland). The data consist mainly of field measurements and experiments conducted during the BIREME project from 2003 to 2006, supplemented with relevant published data. Our main focus was to analyze whether the biological activity in Baltic Sea sea-ice shows clear regional variability. Sea-ice in the Bothnian Bay has low chlorophyll a concentrations, and the bacterial turnover rates are low. However, we have sampled mainly land-fast level first-year sea-ice and apparently missed the most active biological system, which may reside in deformed ice (such as ice ridges). Our limited data set shows high concentrations of algae in keel blocks and keel block interstitial water under the consolidated layer of the pressure ridges in the northernmost part of the Baltic Sea. In land-fast level sea-ice in the Bothnian Sea and the Gulf of Finland, the lowermost layer appears to be the center of biological activity, though elevated biomasses can also be found occasionally in the top and interior parts of the ice. Ice algae are light limited during periods of snow cover, and phosphate is generally the limiting nutrient for ice bottom algae. Bacterial growth is evidently controlled by the production of labile dissolved organic matter by algae because low growth rates were recorded in the Bothnian Bay with high concentrations of allochthonous dissolved organic matter. Bacterial communities in the Bothnian Sea and the Gulf of Finland show high turnover rates, and activities comparable with those of open water communities during plankton blooms, which implies that sea-ice bacterial communities have high capacity to process matter during the winter period.     

Effects of Modern Forest Management on Winter Grazing Resources for Reindeer in Sweden

Boreal forests in Sweden are exploited in a number of ways, including forestry and reindeer husbandry. In the winter, reindeer feed mainly on lichens, and lichen-rich forests are a key resource in the herding system. Commercial forestry has mainly negative effects on reindeer husbandry, and conflicts between these two industries have escalated over the last century. This article reviews the effects of modern forest management practices on the winter resources available for reindeer husbandry. Forestry affects reindeer husbandry at both the stand level and the landscape level and over various time scales. Clear-cutting, site preparation, fertilization, short rotation times, and forest fragmentation have largely resulted in a reduced amount of ground growing and arboreal lichens and restricted access to resource. This article also discusses alternative forestry practices and approaches that could reduce the impacts of forestry on reindeer husbandry, both in the short and long term.     

Omnivory and grazer functional composition moderate cascading trophic effects in experimental <Emphasis Type="Italic">Fucus vesiculosus</Emphasis> habitats

We tested the relative strength of direct versus indirect effects of an aquatic omnivore depending on the functional composition of grazers by manipulating the presence of gastropod and amphipod grazers and omnivorous shrimp in outdoor mesocosms. By selectively preying upon amphipods and reducing their abundance by 70–80%, omnivorous shrimp favoured the dominance of gastropods. While gastropods were the main microalgal grazers, amphipods controlled macroalgal biomass in the experiment. However, strong predation on the amphipod by the shrimp had no significant indirect effects on macroalgal biomass, indicating that when amphipod abundances declined, complementary feeding by the omnivore on macroalgae may have suppressed a trophic cascade. Accordingly, in the absence of amphipods, the shrimp grazed significantly on green algae and thereby suppressed the diversity of the macroalgal community. Our experiment demonstrates direct consumer effects by an omnivore on both the grazer and producer trophic levels in an aquatic food web, regulated by prey availability.     

粮食生产系统中的镉:对敏感人群的健康威胁

本文概述了瑞典农业系统中镉的状况以及镉的人类暴露状况.农业土壤(耕层)中的镉每年增加0.03%～0.05%.饲料是当地农业系统中镉增加的重要原因.当前暴露水平下已经有一些测量表明人体肾功能受到影响.如果粮食中的水平达到欧盟允许的最大限度,那么10%～25%的瑞典人群暴露的镉水平将超过暂时可容忍的每周摄入量(PTWI,7μg Cd/kg体重).人群中的敏感者是那些低铁状况(主要是女性)和肾紊乱的个体.最近的研究表明镉对骨质疏松症有影响,但还需要进一步的研究来辨别镉是否在早期发展阶段毒害神经.必须采取坚决行动来阻止农业土壤中镉含量进一步增加.本文给出了预防及采取措施的建议.     

Landfill mining: a critical review of two decades of research

Landfills have historically been seen as the ultimate solution for storing waste at minimum cost. It is now a well-known fact that such deposits have related implications such as long-term methane emissions, local pollution concerns, settling issues and limitations on urban development. Landfill mining has been suggested as a strategy to address such problems, and in principle means the excavation, processing, treatment and/or recycling of deposited materials. This study involves a literature review on landfill mining covering a meta-analysis of the main trends, objectives, topics and findings in 39 research papers published during the period 1988-2008. The results show that, so far, landfill mining has primarily been seen as a way to solve traditional management issues related to landfills such as lack of landfill space and local pollution concerns. Although most initiatives have involved some recovery of deposited resources, mainly cover soil and in some cases waste fuel, recycling efforts have often been largely secondary. Typically, simple soil excavation and screening equipment have therefore been applied, often demonstrating moderate performance in obtaining marketable recyclables. Several worldwide changes and recent research findings indicate the emergence of a new perspective on landfills as reservoirs for resource extraction. Although the potential of this approach appears significant, it is argued that facilitating implementation involves a number of research challenges in terms of technology innovation, clarifying the conditions for realization and developing standardized frameworks for evaluating economic and environmental performance from a systems perspective. In order to address these challenges, a combination of applied and theoretical research is required.     

Replacing monocultures with mixed-species stands: Ecosystem service implications of two production forest alternatives in Sweden

Whereas there is evidence that mixed-species approaches to production forestry in general can provide positive outcomes relative to monocultures, it is less clear to what extent multiple benefits can be derived from specific mixed-species alternatives. To provide such insights requires evaluations of an encompassing suite of ecosystem services, biodiversity, and forest management considerations provided by specific mixtures and monocultures within a region. Here, we conduct such an assessment in Sweden by contrasting even-aged Norway spruce (Picea abies)-dominated stands, with mixed-species stands of spruce and birch (Betula pendula or B. pubescens), or spruce and Scots pine (Pinus sylvestris). By synthesizing the available evidence, we identify positive outcomes from mixtures including increased biodiversity, water quality, esthetic and recreational values, as well as reduced stand vulnerability to pest and pathogen damage. However, some uncertainties and risks were projected to increase, highlighting the importance of conducting comprehensive interdisciplinary evaluations when assessing the pros and cons of mixtures.