Total and methyl mercury concentrations and fluxes from small boreal forest catchments in Finland

Total mercury (TotHg) and methyl mercury (MeHg) concentrations were studied in runoff from eight small (0.02-1.3 km2) boreal forest catchments (mineral soil and peatland) during 1990-1995. Runoff waters were extremely humic (TOC 7-70 mg l-1). TotHg concentrations varied between 0.84 and 24 ng l-1 and MeHg between 0.03 and 3.8 ng l-1. TotHg fluxes from catchments ranged from 0.92 to 1.8 g km-2 a-1, and MeHg fluxes from 0.03 to 0.33 g km-2 a-1. TotHg concentrations and output fluxes measured in runoff water from small forest catchments in Finland were comparable with those measured in other boreal regions. By contrast, MeHg concentrations were generally higher. Estimates for MeHg output fluxes in this study were comparable at sites with forests and wetlands in Sweden and North America, but clearly higher than those measured at upland or agricultural sites in other studies. Peatland catchments released more MeHg than pure mineral soil or mineral soil catchments with minor area of peatland.     

Mobility and Methylation of Mercury in Forest Soils Development of an In-Situ Stable Isotope Tracer Technique and Initial Results

A method for investigating in-situmethylation and mobility of mercury has beendeveloped and applied to forest soil. The methodis based on additions of stable ¹⁹⁹Hgisotopes to forest soil plots followed bysampling and analysis of isotope ratios of totalmercury and MeHg using ICP-MS. Initial resultsindicate that a fraction (30%) of the mercuryadded to the forest soils is immobilised over atime scale of 16 months. A small but significantfraction of the mercury is methylated during thesame time scale. Higher methylation rates werefound in wetland soil than in dry forest podzolsoil.     

Occurrence and rates of terminal electron-accepting processes and recharge processes in petroleum hydrocarbon-contaminated subsurface

The occurrence and rates of terminal electron acceptor processes, and recharge processes in the unsaturated zone of a boreal site contaminated with petroleum hydrocarbons in the range C(10) to C(40) were examined. Soil microcosms were used to determine the rates of denitrification, iron (Fe) reduction, sulfate (SO(4)) reduction, and methanogenesis in two vertical soil profiles contaminated with oil, and in a noncontaminated reference sample. Furthermore, the abundances of the 16S rRNA genes belonging to Geobacteracaea in the samples were determined by real-time quantitative polymerase chain reaction (PCR). Analyses of ground water chemistry and soil gas composition were also performed together with continuous in situ monitoring of soil water and ground water chemistry. Several lines of evidence were obtained to demonstrate that both Fe reduction and methanogenesis played significant roles in the vertical profiles: Fe reduction rates up to 3.7 nmol h(-1) g(-1) were recorded and they correlated with the abundances of the Geobacteracaea 16S rRNA genes (range: 2.3 x 10(5) to 4.9 x 10(7) copies g(-1)). In the ground water, ferrous iron (Fe(2+)) concentration up to 55 mg L(-1) was measured. Methane production rates up to 2.5 nmol h(-1) g(-1) were obtained together with methane content up to 15% (vol/vol) in the soil gas. The continuous monitoring of soil water and ground water chemistry, microcosm experiments, and soil gas monitoring together demonstrated that the high microbial activity in the unsaturated zone resulted in rapid removal of oxygen from the infiltrating recharge thus leaving the anaerobic microbial processes dominant below 1.5 m depth both in the unsaturated and the saturated zones of the subsurface.     

Roadside aerosol study using hygroscopic,organic and volatility TDMAs: Characterization and mixing state

Traffic-related aerosol particles are ubiquitous in the urban atmosphere. As they are produced at ground level, they can also cause adverse health effects to urban dwellers. However, knowledge of the formation, transformation and chemically resolved size distribution of urban ultrafine particles is incomplete. Thus, more of these measurements are needed for better assessment of ambient air quality and its potential health effects. The particle number concentration, aerosol black carbon (BC) concentration and size distribution of traffic-related aerosols were measured near two major roads in Kuopio, Finland, from 16 June to 5 July, 2004. Furthermore, the properties of roadside aerosol particles were examined with the Tandem Differential Mobility Analyzer technique (TDMA). A suite of TDMA instruments relying on water (hygroscopic TDMA) and ethanol (organic TDMA) condensation as well as heating (volatility TDMA) were deployed to study the composition of the nucleation and Aitken mode particles (D_p = 10–50 nm) formed from vehicle exhaust. The results show that a simple three-component model was able to reproduce characteristic insoluble, organic and water-soluble volume fractions. Insoluble constituents were dominant in the Aitken mode particles, whereas organic compounds dominated the nucleation mode sizes. On average, only a small volume fraction was water-soluble, but a clear external mixing was observed particularly when enough time was allowed after the tail pipe emissions. The contribution of the insoluble material was seen to increase as a function of particle size, being typically less than 10% at 10 nm and between 20 and 50% at 50 nm, in contrast to the organic fraction, which decreased from about 80% at nucleation mode size range to 50–60% at 50 nm.     

Bacterial community changes in response to oil contamination and perennial crop cultivation

Environmental Science and Pollution Research - We investigated bacterial community dynamics in response to used motor oil contamination and perennial crop cultivation by 16S rRNA gene amplicon...     

Developing interdisciplinary environmental frameworks

The purpose of this article is to review interdisciplinary systemic frameworks of environmental protection and evaluate their use as tools, educational policymaking and education. We analyze the pressures-state-responses (PSR) framework of the Organization for Economic Cooperation and Development, the drivers-pressures-state-impact-response (DPSIR) framework developed in the European Environment Agency and a later environmental political dynamics framework developed by Schroll and Staerdahl. We then continue the discussion by introducing a comprehensive model, labeled as the environmental protection process (EPP) framework that can be used to analyze and teach why there are environmental problems, what are their characteristics, and in which ways they can be mitigated. The EPP model is used for classifying measures of coping with environmental problems. Finally, a submodel of individual and societal factors affecting human action is formed. Environmental issues of transport are used as an illustrative example. We hope to contribute a relevant way to outline a wide interdisciplinary picture of environmental problems and solutions.     

Effectiveness of Constructed Overland Flow Areas in Decreasing Diffuse Pollution from Forest Drainages

Forestry is the largest scale human impact affecting catchments in Finland and a prominent source of diffuse pollution in many water courses. Among the forestry activities, draining of wetlands had the most pronounced impacts on sediment, nutrient, and metal loading in the past. At present, renovation of old ditches and fertilization of peatlands constitute the major risk of forestry-induced diffuse pollution. Contemporary forestry aims at decreasing this risk with various riparian buffer strip designs. Among such designs, creation of overland flow areas by plugging the outlet ditches is increasingly used. Our objectives were to evaluate the potential of constructed overland flow areas to function as riparian buffers and estimate the quality and quantity of diffuse pollution from old versus recent forest drainages. We studied retention and release of pollutants from 20 constructed, 2- to 10-m-wide overland flow areas receiving drainage water from forested peatlands. Drainage waters were sampled above and below the plugged ditches three times per year from 1998 to 1999. Chemical oxygen demand and nutrient and metal loads and concentrations varied strongly between seasons, years, and drainage areas. Areas subjected to recent ditch renovations and fertilizations had clearly elevated seasonal loads and concentrations of total phosphorus (TP), PO₄, Fe, and Al in comparison to old treatment areas. Especially TP loads were high above the national average values measured for forestry-induced diffuse pollution. In general, water quality above and below the buffer strips did not differ significantly. Our results indicate that plugged outlet ditches and associated narrow overland flow areas do not function as proper buffers in peatland areas. We suggest that wider buffers with extensive overland flow areas are needed in order to control diffuse pollution from forested and drained peatlands.     

Voluntary exercise at the expense of reproductive success in Djungarian hamsters (Phodopus sungorus)

Energy demands of gestation and lactation represent a severe challenge for small mammals. Therefore, additional energetic burdens may compromise successful breeding. In small rodents, food restriction, cold exposure (also in combination) and wheel running to obtain food have been shown to diminish reproductive outcome. Although exhibited responses such as lower incidence of pregnancy, extended lactation periods and maternal infanticide were species dependent, their common function is to adjust energetic costs to the metabolic state reflecting the trade-off between maternal investment and self-maintenance. In the present study, we sought to examine whether voluntary exercise affects reproduction in Djungarian hamsters (Phodopus sungorus), which are known for their high motivation to run in a wheel. Voluntary exercise resulted in two different effects on reproduction; in addition to increased infanticide and cannibalism, which was evident across all experiments, the results of one experiment provided evidence that free access to a running wheel may prevent successful pregnancy. It seems likely that the impact of voluntary wheel running on reproduction was associated with a reduction of internal energy resources evoked by extensive exercise. Since the hamsters were neither food-restricted nor forced to run in the present study, an energetic deficit as reason for infanticide in exercising dams would emphasise the particularly high motivation to run in a wheel.