Land use influences macroinvertebrate community composition in boreal headwaters through altered stream conditions

Land use is known to alter the nature of land–water interactions, but the potential effects of widespread forest management on headwaters in boreal regions remain poorly understood. We evaluated the importance of catchment land use, land cover, and local stream variables for macroinvertebrate community and functional trait diversity in 18 boreal headwater streams. Variation in macroinvertebrate metrics was often best explained by in-stream variables, primarily water chemistry (e.g. pH). However, variation in stream variables was, in turn, significantly associated with catchment-scale forestry land use. More specifically, streams running through catchments that were dominated by young (11–50 years) forests had higher pH, greater organic matter standing stock, higher abundance of aquatic moss, and the highest macroinvertebrate diversity, compared to streams running through recently clear-cut and old forests. This indicates that catchment-scale forest management can modify in-stream habitat conditions with effects on stream macroinvertebrate communities and that characteristics of younger forests may promote conditions that benefit headwater biodiversity.     

Elemental mobility in sulfidic mine tailings reclaimed with paper mill by-products as sealing materials

Environmental Science and Pollution Research - Sealing layers made of two alkaline paper mill by-products, fly ash and green liquor dregs, were placed on top of 50-year-old sulfide-containing...     

Influence of age,season, body condition and geographical area on concentrations of chlorinated and brominated contaminants in wild mink (Neovison vison) in Sweden

The wild mink has gained acceptance as a sentinel species in environmental monitoring. However, only limited data are available in the literature on factors driving variability in concentrations of organic pollutants in this species. This study characterizes the differences in contaminant concentrations in subcutaneous fat of male mink from four different areas in Sweden and demonstrates how age, season and body condition influence concentrations of polychlorinated biphenyl (PCB) congeners, polybrominated diphenyl ether (PBDE) congeners (including methoxylated forms, MeO-PBDEs), as well as the pesticides dichlorodiphenyldichloroethylene (DDE), chlordane and hexachlorobenzene (HCB). The data were statistically treated using multiple regression and principal component analysis. The ∑PCB concentration and concentrations of PCB congeners 138, 156, 157, 180, 170/190, 189, 194, 206, 209 as well as PBDE 153/154 varied with age. Season had an influence on ∑PCB, PBDE 47 and PBDE 153/154 concentrations, as well as concentrations of most PCB congeners, with the exception of PCB 101, 110, 141 and 182/187. Lean mink had higher concentrations of most PCBs and PBDEs than mink with larger fat depots. The analyzed pesticides (DDE, oxychlordane, HCB) showed no systematic variation with season, age or body condition. The concentrations of MeO-PBDEs were generally low and 6MeO-PBDE 47 was the most commonly detected MeO-PBDE in mink from marine, brackish and freshwater areas. The results indicate that age, season and body condition are factors that may influence the concentrations of PCBs and PBDEs, and it is thus recommended to take these factors into account when analyzing mink exposure data.     

The Effects of Hypoxia on Sediment Nitrogen Cycling in the Baltic Sea

Primary production in the eutrophic Baltic Sea is limited by nitrogen availability; hence denitrification (natural transformation of nitrate to gaseous N₂) in the sediments is crucial in mitigating the effects of eutrophication. This study shows that dissimilatory nitrate reduction to ammonium (DNRA) process, where nitrogen is not removed but instead recycled in the system, dominates nitrate reduction in low oxygen conditions (O₂ <110 μM), which have been persistent in the central Gulf of Finland during the past decade. The nitrogen removal rates measured in this study show that nitrogen removal has decreased in the Gulf of Finland compared to rates measured in mid-1990s and the decrease is most likely caused by the increased bottom water hypoxia.     

Activated carbon amendment to sequester PAHs in contaminated soil: a lysimeter field trial

Activated carbon (AC) amendment is an innovative method for the in situ remediation of contaminated soils. A field-scale AC amendment of either 2% powder or granular AC (PAC and GAC) to a PAH contaminated soil was carried out in Norway. The PAH concentration in drainage water from the field plot was measured with a direct solvent extraction and by deploying polyoxymethylene (POM) passive samplers. In addition, POM samplers were dug directly in the AC amended and unamended soil in order to monitor the reduction in free aqueous PAH concentrations in the soil pore water. The total PAH concentration in the drainage water, measured by direct solvent extraction of the water, was reduced by 14% for the PAC amendment and by 59% for GAC, 12 months after amendment. Measurements carried out with POM showed a reduction of 93% for PAC and 56% for GAC. The free aqueous PAH concentration in soil pore water was reduced 93% and 76%, 17 and 28 months after PAC amendment, compared to 84% and 69% for GAC. PAC, in contrast to GAC, was more effective for reducing freely dissolved concentrations than total dissolved ones. This could tentatively be explained by leaching of microscopic AC particles from PAC. Secondary chemical effects of the AC amendment were monitored by considering concentration changes in dissolved organic carbon (DOC) and nutrients. DOC was bound by AC, while the concentrations of nutrients (NO(3), NO(2), NH(4), PO(4), P-total, K, Ca and Mg) were variable and likely affected by external environmental factors.     

NAPL migration and ecotoxicity of conventional and renewable fuels in accidental spill scenarios

Fuels derived from non-petroleum renewable resources have raised interest due to their potential in replacing petroleum-based fuels, but information on their fate and effects in the terrestrial and aquatic environments in accidental spill scenario is limited. In this study, migration of four fuels (conventional diesel, conventional gasoline, renewable diesel NExBTL, and ethanol-blended gasoline RE85 containing maximum 85 % ethanol) as non-aqueous phase liquids (NAPL) in soil was demonstrated in a laboratory-scale experiment. Ecotoxicity data was produced for the same fuels. There was no significant difference in migration of conventional and renewable diesel, but gasoline migrated 1.5 times deeper and 7–9 times faster in sand than diesel. RE85 spread horizontally wider but not as deep (p?Eisenia fetida followed by ethanol-blended gasoline (LC50 1,643 mg/kg THC) and conventional diesel (LC50 2,432 mg/kg THC), although gasoline evaporated fast from soil. For comparison, the toxicity of the water-accommodated fractions (WAF) of the fuels was tested with water flea Daphnia magna and Vibrio fischeri, also demonstrating groundwater toxicity. The WAF of conventional gasoline and RE85 showed almost similar toxicity to both the aquatic test species. EC50 values of 1:10 (by volume) WAF were 9.9 %WAF (gasoline) and 9.3 %WAF (RE85) to D. magna and 9.3 %WAF (gasoline) and 12.3 %WAF (RE85) to V. fischeri. Low solubility decreased toxicity potential of conventional diesel in aquatic environment, but direct physical effects of oil phase pose a threat to organisms in nature. Renewable diesel NExBTL did not show clear toxicity to any test species.     

Effects of light and temperature fluctuations on the growth of Myriophyllum spicatum in toxicity tests—a model-based analysis

Laboratory toxicity tests are a key component of the aquatic risk assessments of chemicals. Toxicity tests with Myriophyllum spicatum are conducted based on working procedures that provide detailed instructions on how to set up the experiment, e.g., which experimental design is necessary to get reproducible and thus comparable results. Approved working procedures are established by analyzing numerous toxicity tests to find a compromise between practical reasons (e.g., acceptable ranges of ambient conditions as they cannot be kept completely constant) and the ability for detecting growth alterations. However, the benefit of each step of a working procedure, e.g., the random repositioning of test beakers, cannot be exactly quantified, although this information might be useful to evaluate working procedures. In this paper, a growth model of M. spicatum was developed and used to assess the impact of temperature and light fluctuations within the standardized setup. It was analyzed how important it is to randomly reassign the location of each plant during laboratory tests to keep differences between the relative growth rates of individual plants low. Moreover, two examples are presented on how modeling can give insight into toxicity testing. Results showed that randomly repositioning of individual plants during an experiment can compensate for fluctuations of light and temperature. A method is presented on how models can be used to improve experimental designs and to quantify their benefits by predicting growth responses.     

Environmental effects of soil contamination by shale fuel oils

Estonia is currently one of the leading producers of shale oils in the world. Increased production, transportation and use of shale oils entail risks of environmental contamination. This paper studies the behaviour of two shale fuel oils (SFOs)—‘VKG D’ and ‘VKG sweet’—in different soil matrices under natural climatic conditions. Dynamics of SFOs’ hydrocarbons (C10–C40), 16 PAHs, and a number of soil heterotrophic bacteria in oil-spiked soils was investigated during the long-term (1 year) outdoor experiment. In parallel, toxicity of aqueous leachates of oil-spiked soils to aquatic organisms (crustaceans Daphnia magna and Thamnocephalus platyurus and marine bacteria Vibrio fischeri) and terrestrial plants (Sinapis alba and Hordeum vulgare) was evaluated. Our data showed that in temperate climate conditions, the degradation of SFOs in the oil-contaminated soils was very slow: after 1 year of treatment, the decrease of total hydrocarbons’ content in the soil did not exceed 25 %. In spite of the comparable chemical composition of the two studied SFOs, the VKG sweet posed higher hazard to the environment than the heavier fraction (VKG D) due to its higher mobility in the soil as well as higher toxicity to aquatic and terrestrial species. Our study demonstrated that the correlation between chemical parameters (such as total hydrocarbons or total PAHs) widely used for the evaluation of the soil pollution levels and corresponding toxicity to aquatic and terrestrial organisms was weak.     

Toxicity of hydroquinone to different freshwater phototrophs is influenced by time of exposure and pH

The interaction of natural organic matter with phytoplankton communities in freshwater ecosystems is an intensively studied subject matter. Previous studies showed that apparently plant-derived phenols were able to inhibit algal and cyanobacterial growth. Furthermore, it was also assumed that humic substances (HS), which comprise the major part of dissolved organic carbon in freshwater ecosystems, directly interact with freshwater phototrophs. For example, quinoid building blocks of HS were thought to be algicidal. To identify key environmental variable for the toxic action of potential quinone algicides, we tested the toxicity of hydroquinone (HQ) to different eukaryotic and prokaryotic freshwater phototrophs in terms of growth performance and investigated also the effect of HQ oxidation at different pH values on its algicidal potential. It was shown that cyanobacterial species were much more susceptible to hydroquinone than coccal green algal species were, with Microcystis aeruginosa being the most sensitive species by far. In addition, it was obvious that the aging of hydroquinone-stock solution at pH 11 led to polymerization and, by this process, to a total loss of toxicity; whereas the algicidal potential sustained if the polyphenol was kept at pH 7. Since most lakes with heavy blooms of phototrophs possess pH values clearly above 7.0, it is questionable, if polyphenols in general and quinones in particular are the effective chemicals and if litter and straw leachates are applied as means to combat algal and cyanobacterial blooms.     

An integrated approach to model the biomagnification of organic pollutants in aquatic food webs of the Yangtze Three Gorges Reservoir ecosystem using adapted pollution scenarios

The impounding of the Three Gorges Reservoir (TGR) at the Yangtze River caused large flooding of urban, industrial, and agricultural areas, and profound land use changes took place. Consequently, substantial amounts of organic and inorganic pollutants were released into the reservoir. Additionally, contaminants and nutrients are entering the reservoir by drift, drainage, and runoff from adjacent agricultural areas as well as from sewage of industry, aquacultures, and households. The main aim of the presented research project is a deeper understanding of the processes that determines the bioaccumulation and biomagnification of organic pollutants, i.e., mainly pesticides, in aquatic food webs under the newly developing conditions of the TGR. The project is part of the Yangtze-Hydro environmental program, financed by the German Ministry of Education and Science. In order to test combinations of environmental factors like nutrients and pollution, we use an integrated modeling approach to study the potential accumulation and biomagnification. We describe the integrative modeling approach and the consecutive adaption of the AQUATOX model, used as modeling framework for ecological risk assessment. As a starting point, pre-calibrated simulations were adapted to Yangtze-specific conditions (regionalization). Two exemplary food webs were developed by a thorough review of the pertinent literature. The first typical for the flowing conditions of the original Yangtze River and the Daning River near the city of Wushan, and the second for the stagnant reservoir characteristics of the aforementioned region that is marked by an intermediate between lake and large river communities of aquatic organisms. In close cooperation with German and Chinese partners of the Yangtze-Hydro Research Association, other site-specific parameters were estimated. The MINIBAT project contributed to the calibration of physicochemical and bathymetric parameters, and the TRANSMIC project delivered hydrodynamic models for water volume and flow velocity conditions. The research questions were firstly focused on the definition of scenarios that could depict representative situations regarding food webs, pollution, and flow conditions in the TGR. The food webs and the abiotic site conditions in the main study area near the city of Wushan that determine the environmental preconditions for the organisms were defined. In our conceptual approach, we used the pesticide propanil as a model substance.