Comparison of first-order-decay modeled and actual field measured municipal solid waste landfill methane data

The first-order decay (FOD) model is widely used to estimate landfill gas generation for emissions inventories, life cycle assessments, and regulation. The FOD model has inherent uncertainty due to underlying uncertainty in model parameters and a lack of opportunities to validate it with complete field-scale landfill data sets. The objectives of this paper were to estimate methane generation, fugitive methane emissions, and aggregated collection efficiency for landfills through a mass balance approach using the FOD model for gas generation coupled with literature values for cover-specific collection efficiency and methane oxidation. This study is unique and valuable because actual field data were used in comparison with modeled data. The magnitude and variation of emissions were estimated for three landfills using site-specific model parameters and gas collection data, and compared to vertical radial plume mapping emissions measurements. For the three landfills, the modeling approach slightly under-predicted measured emissions and over-estimated aggregated collection efficiency, but the two approaches yielded statistically equivalent uncertainties expressed as coefficients of variation. Sources of uncertainty include challenges in large-scale field measurement of emissions and spatial and temporal fluctuations in methane flow balance components (generated, collected, oxidized, and emitted methane). Additional publication of sets of field-scale measurement data and methane flow balance components will reduce the uncertainty in future estimates of fugitive emissions.     

Mechanically-biologically treated municipal solid waste as a support medium for microbial methane oxidation to mitigate landfill greenhouse emissions

The residual fraction of mechanically-biologically treated municipal solid waste (MBT residual) was studied in the laboratory to evaluate its suitability and environmental compatibility as a support medium in methane (CH(4)) oxidative biocovers for the mitigation of greenhouse gas emissions from landfills. Two MBT residuals with 5 and 12 months total (aerobic) biological stabilisation times were used in the study. MBT residual appeared to be a favourable medium for CH(4) oxidation as indicated by its area-based CH(4) oxidation rates (12.2-82.3 g CH(4) m(-2) d(-1) at 2-25 degrees C; determined in CH(4)-sparged columns). The CH(4) oxidation potential (determined in batch assays) of the MBT residuals increased during the 124 d column experiment, from <1.6 to a maximum of 104 microg CH(4) g(dw)(-1) h(-1) (dw=dry weight) at 5 degrees C and 578 microg CH(4) g(dw)(-1) h(-1) at 23 degrees C. Nitrous oxide (N(2)O) production in MBT residual (<15 microg N(2)O kg(dw)(-1) d(-1) in the CH(4) oxidative columns) was at the lower end of the range of N(2)O emissions reported for landfills and non-landfill soils, and insignificant as a greenhouse gas source. Also, anaerobic gas production (25.6 l kg(dw)(-1) during 217 d) in batch assays was low, indicating biological stability of the MBT residual. The electrical conductivities (140-250 mS m(-1)), as well as the concentrations of zinc (3.0 mg l(-1)), copper (0.5 mg l(-1)), arsenic (0.3 mg l(-1)), nickel (0.1 mg l(-1)) and lead (0.1 mg l(-1)) in MBT residual eluates from a leaching test (EN-12457-4) with a liquid/solid (L/S) ratio of 10:1, suggest a potential for leachate pollutant emissions which should be considered in plans to utilise MBT residual. In conclusion, the laboratory experiments suggest that MBT residual can be utilised as a support medium for CH(4) oxidation, even at low temperatures, to mitigate greenhouse gas emissions from landfills.     

Human dietary intake of organochlorines from Baltic herring: implications of individual fish variability and fisheries management

This study examines the extent to which Finnish human dietary intake of organochlorines (PCDD/Fs and PCBs) originating from Northern Baltic herring can be influenced by fisheries management. This was investigated by estimation of human intake using versatile modeling tools (e.g., a herring population model and a bioenergetics model). We used a probabilistic approach to account for the variation in human intake of organochlorines originating from the variation among herring individuals. Our estimates were compared with present precautionary limits and recommendation for use. The results show that present consumption levels and frequencies of herring give a high probability of exceeding recommended intake limits of PCDD/Fs and PCBs. Furthermore, our results clearly demonstrate that in the risk management of dioxinlike organochlorines, regulating fishing (in this case increasing fishing pressure) is a far less effective way to decrease the risk than regulating the consumption of herring. Increased fishing would only slightly decrease organochlorine concentrations of herring in the Finnish fish market.     

Effects of eutrophication and organic loading on the occurrence of profundal harpacticoids in a lake in southern Finland

Harpacticoids made up 19 and 30% of the meiobenthos proper by number and 39 and 55% by biomass at maximum depths and a depth of 20 m, respectively, in Lake Päijänne. Harpacticoids accounted for higher proportions of the total meiobenthos in oligotrophic and unpolluted areas than in polluted areas. Seven species were identified, with Canthocamptus staphylinus confined to semi-lotic areas influenced by organic pollution from a pulp mill. Other species exhibited somewhat different distributions in oligotrophic and mesotrophic areas. Harpacticoid densities were most closely correlated with oxygen content and phytoplankton biomass, and correlations with environmental values were closer at maximum depths than at 20 m. Attheyella crassa densities in the deepest zone had most marked negative correlation with total phosphorus, phytoplankton biomass, dissolved organic matter and organic sedimentation, while Paracamptus schmeili had the closest positive correlation with oxygen content. High densities of these species could be classified as an indicator of oligotrophic conditions. Similar correlations, although weaker, were evident for Bryocamptus minutus and still weaker for Bryocamptus echinatus and Moraria brevipes. Clustering of the stations based on harpacticoid abundances gave a similar result to clustering based on environmental data, particularly in the 20 m zone.     

Do brain parasites alter host personality? — Experimental study in minnows

Despite that the existence of animal personalities is widely recognized, no consensus has been reached on the relative importance of different ecological factors behind their expression. Recently, it has been suggested that parasites may have a crucial role in shaping animal personalities, but only a very few studies have experimentally tested the idea. We infected Eurasian minnows (Phoxinus phoxinus) with the brain-encysted trematode parasite, Diplostomum phoxini, and studied whether infection could modify the personality of their hosts. Our results show that D. phoxini infection did not affect the mean levels of boldness, activity or exploration, but infected minnows showed higher repeatability in boldness and activity, and reduced repeatability in exploration. We also found that D. phoxini may be able to break the associations (behavioral syndromes) between behavioral traits, but that this effect may be dependent on parasite intensity. Furthermore, the effect of D. phoxini infection on personality of the hosts was found to be nonlinearly dependent on infection intensity. Taken together, our results suggest that D. phoxini parasites may shape the personality of their hosts, but that behavioral consequences of ecologically relevant infection levels may be rather subtle and easily remain undetected if only the mean trait expressions are compared.     

Safety compliance climate concerning risk assessment and preventive measures in EU legislation: A Finnish survey

The aim of the present study is to explore the process dynamics of the safety compliance climate and work relationships, including their antecedents and consequences. After investigating the many dimensions of safety compliance climate and of work relationships, the study concludes that a multi-component measure is needed to fully assess all of their dimensions. With respect to the impacting positively on safety compliance legislation, the present study found the following factors: “contribution measures”, “concrete preventive measures” and “risk assessment process”. For risk assessment factors on safety compliance the study identified “planning, guidelines, policy, management”, “prioritization of proactive measures”, “results in cooperation and information” and “active use of risks assessment document”. In a regression model for the workers, both risk assessment process and contribution measures had a statistically highly significant (p < 0.001) effect on concrete preventive measures. In the regression analysis of the employers risk assessment process had a statistically significant (p < 0.01) effect and contribution measures had a statistically highly significant (p < 0.001) effect on concrete preventive measures.     

Contribution of winter to the annual CH4 emission from a eutrophied boreal lake

The springtime methane (CH4) emission from a small, eutrophied boreal lake was assessed during the winter ice-cover by measurement of gas ebullition and CH4 accumulation in the water column in association with the development of oxygen depletion after ice formation. The winter CH4 production was estimated to result in a loss of 3.6-7.9 g CH4 m(-2) from the lake to the atmosphere during the short period of ice melt. This could account for 22-48% of the annual CH4 emission from the pelagic zone of the lake. The contribution of winter to the annual CH4 release can be similar or even higher in seasonally ice-covered northern aquatic ecosystems than in northern terrestrial wetlands, thus winter must be considered in any studies into the aquatic CH4 emissions. The trophic state and wintertime oxygen conditions, linked to the changes in land-use in the catchments and climate, are important factors controlling the springtime lake CH4 emissions.     

Food chain enrichment of organochlorine compounds and mercury in clean and polluted lakes of Finland

Lakes polluted by pulp mill and urban wastes including chlorobleaching of pulp, semipolluted lakes and reference lakes in nearly natural condition in Central Finland were studied for contents of mercury, methyl mercury and organochlorine compounds in sediment, plankton, roach and pike. Chlorobleaching had caused a 30-fold concentration of Hg in bottom sediment related to that of the purest reference lake. This was not reflected to the mercury levels in fish which were highest at one natural condition (humic) lake and rather high also at semipolluted lake Päijänne. Mercury in fish was shown to be mostly methylated but not completely and its time trends could be estimated. Chloroform showed no but carbon tetrachloride, tetrachloroethylene and chlorinated cymenes significant bioaccumulation in fish. Levels of chlorophenols from bleaching had strongly decreased but pentachlorophenol and 2,3,4,6-tetrachlorphenol levels remained related to earlier results. Using fat basis attenuated the power of estimation of food chain enrichment by a three throphic level model for lipohilic biocides and a strong proof was obtained of the enrichment of hexachlorobenzene. The time trends at Päijänne were decreasing for mercury and DDE but increasing for PCB.     

Short- and long-term patterns of ¹³⁷Cs in fish and other aquatic organisms of small forest lakes in southern Finland since the Chernobyl accident

We summarize the patterns of ¹³⁷Cs activity concentrations and transfer into fish and other biota in four small forest lakes in southern Finland during a twenty-year period following the Chernobyl accident in April 1986. The results from summer 1986 showed fastest accumulation of ¹³⁷Cs into planktivorous fishes, i.e. along the shortest food chains. Since 1987, the highest annual mean values of ¹³⁷Cs have been recorded in fish occupying the highest trophic levels, for perch (Perca fluviatilis) 13,600 Bq/kg (ww) and for pike (Esox lucius) 20,700 Bq/kg (ww). At the same time, activity concentrations of ¹³⁷Cs in crustacean zooplankton and Asellus aquaticus have ranged between 1000 and 19,500 Bq/kg (dw). In 2006, 5-28% of the 1987 ¹³⁷Cs activity concentration levels were still present in perch and pike. Since 1989 their ¹³⁷Cs activity concentrations in oligohumic seepage lakes have remained significantly higher than in polyhumic drainage lakes due to the increased transfer of ¹³⁷Cs into fish in the seepage lakes with lower electrolyte concentrations, longer water retention times and lower sedimentation rate.