| 1. |
- Bostedt, Göran, 1966-, et al.
(författare)
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Acidification Remediation Alternatives : Exploring the Temporal Dimension with Cost Benefit Analysis
- 2010
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 39:1, s. 40-48
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Tidskriftsartikel (refereegranskat)abstract
- Acidification of soils and surface waters caused by acid deposition is still a major problem in southern Scandinavia, despite clear signs of recovery. Besides emission control, liming of lakes, streams, and wetlands is currently used to ameliorate acidification in Sweden. An alternative strategy is forest soil liming to restore the acidified upland soils from which much acidified runoff originates. This cost-benefit analysis compared these liming strategies with a special emphasis on the time perspective for expected benefits. Benefits transfer was used to estimate use values for sport ffishing and nonuse values in terms of existence values. The results show that large-scale forest soil liming is not socioeconomically profitable, while lake liming is, if it is done efficiently-in other words, if only acidified surface waters are treated. The beguiling logic of "solving'' an environmental problem at its source (soils), rather than continuing to treat the symptoms (surface waters), is thus misleading.
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| 2. |
- Gren, Ing-Marie, et al.
(författare)
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Policy design for a multifunctional landscape
- 2010
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Ingår i: Regional Environmental Change. - : Springer Science and Business Media LLC. - 1436-3798 .- 1436-378X. ; 10:4, s. 339-348
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Tidskriftsartikel (refereegranskat)abstract
- Landscapes consisting of several elements, such as wetlands and forests, are multifunctional in nature and produce both market and non-market goods. The need for policies arises from the existence of non-market ecosystem services that are not traded and thereby generally not subject to economic trade-offs in landowner decision making. An efficient incentive scheme for producing both types of goods would require policy designed for each non-market good. However, this may result in high transaction costs, possibly giving second-best solutions a comparative advantage when only one non-market good is regulated. This paper demonstrates that in the Hovran catchment area in mid Sweden, which produces the non-market goods water quality, biodiversity, and scenic beauty, compensation payments for biodiversity production alone provide almost maximum total net value of all market and non-market goods. On the other hand, payments for providing scenic beauty in the form of open landscape may result in lower total net value than no compensation payment at all, due to a negative impact on water quality.
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| 3. |
- Eklöf, Karin, et al.
(författare)
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Impact of stump harvest on run-off concentrations of total mercury and methylmercury
- 2013
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 290, s. 83-94
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Tidskriftsartikel (refereegranskat)abstract
- Forest harvesting operations have been reported to increase the levels of both total mercury (THg) and methylmercury (MeHg) in runoff water and downstream biota. Mobilization of such harmful substances by logging may pose ecological risks that may be influenced further by site preparation and stump harvest. Stump harvest is currently being explored as a method to increase the supply of biofuels. In this catchment study we investigated the effects of stump harvest, in comparison with ordinary site-preparation, on the runoff concentrations of THg and MeHg as well as several other chemistry parameters. Both treatments were also compared with unharvested reference catchments. Water samples from watercourses draining these catchments were analyzed for various variables including THg, MeHg, total organic carbon, absorbance and total suspended solids. One year of pre-treatment data, starting when the treated areas were just logged, and 2 years of post-treatment data, after stump harvest or site-preparation, were collected with a sample frequency of twice a month. The concentrations of THg and MeHg in the treated areas were decreasing after both stump harvest and site preparation relative to the reference catchment. Further, our results indicate that stump harvest has not caused increased concentrations of any of the studied parameters in relation to traditional site preparation. Two factors are proposed to be responsible for the lack of response to stump harvest and site preparation; (1) the areas are still undergoing recovery from the former logging which may have led to greater Hg export and/or (2) there is variability among sites in how they respond to forestry operations, depending on the biogeochemical and hydrological status of the area. Although no forestry response caused by stump harvest or site preparation was found, we noted that the concentrations of both THg and especially MeHg were high (median THg: 4.5-10.4 ng L-1, median MeHg: 0.7-2.1 ng L-1) in all catchments both before and after treatment, compared to other studies. Variables indicating the organic carbon content were the ones most strongly correlated to the variation of both THg and MeHg in the PLS models based on the dataset from the whole sampling period and all catchments. The relatively high concentrations of THg and MeHg during the study period appeared to be more influenced by organic carbon, but also hydrology and temperature as well as possibly the initial logging rather than by the soil disturbance caused by either stump harvest or site preparation.
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| 4. |
- Bishop, Kevin, et al.
(författare)
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Nature as the "Natural" Goal for Water Management : A Conversation
- 2009
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Ingår i: Ambio. - : Springer Netherlands. - 0044-7447 .- 1654-7209. ; Volume 38:Issue 4
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The goals for water-quality and ecosystem integrity are often defined relative to "natural" reference conditions in many water-management systems, including the European Union Water Framework Directive. This paper examines the difficulties created for water management by using "natural" as the goal. These difficulties are articulated from different perspectives in an informal (fictional) conversation that takes place after a workshop on reference conditions in water-resources management. The difficulties include defining the natural state and modeling how a system might be progressed toward the natural, as well as the feasibility and desirability of restoring a natural state. The paper also considers the appropriateness for developing countries to adopt the use of natural as the goal for water management. We conclude that failure to critically examine the complexities of having "natural" as the goal will compromise the ability to manage the issues that arise in real basins by not making the ambiguities associated with this "natural" goal explicit. This is unfortunate both for the western world that has embraced this model of "natural as the goal" and for the developing world in so far as they are encouraged to adopt this model.
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| 5. |
- Cunningham, Laura, et al.
(författare)
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Paleoecological evidence of major declines in total organic carbon concentrations since the nineteenth century in four nemoboreal lakes
- 2011
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Ingår i: Journal of Paleolimnology. - : Springer. - 0921-2728 .- 1573-0417. ; 45:4, s. 507-518
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Tidskriftsartikel (refereegranskat)abstract
- A decade of widespread increases in surface water concentrations of total organic carbon (TOC) in some regions has raised questions about longer term patterns in this important constituent of water chemistry. This study uses near-infrared spectroscopy (NIRS) to infer lake water TOC far beyond the decade or two of observational data generally available. An expanded calibration dataset of 140 lakes across Sweden covering a TOC gradient from 0.7 to 24.7 mg L-1 was used to establish a relationship between the NIRS signal from surface sediments (0-0.5 cm) and the TOC concentration of the water mass. Internal cross-validation of the model resulted in an R (2) of 0.72 with a root mean squared error of calibration (RMSECV) of 2.6 mg L-1. The TOC concentrations reconstructed from surface sediments in four Swedish lakes were typically within the range of concentrations observed in the monitoring data during the period represented by each sediment layer. TOC reconstructions from the full sediment cores of four lakes indicated that TOC concentrations were approximately twice as high a century ago.
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| 6. |
- Dinsmore, Kerry, et al.
(författare)
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Contrasting CO2 concentration discharge dynamics in headwater streams : a multi-catchment comparison
- 2013
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Ingår i: Journal of Geophysical Research-Biogeosciences. - : American Geophysical Union (AGU). - 2169-8953 .- 2169-8961. ; 118:2, s. 445-461
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Tidskriftsartikel (refereegranskat)abstract
- Aquatic CO2 concentrations are highly variable and strongly linked to discharge, but until recently, measurements have been largely restricted to low-frequency manual sampling. Using new in situ CO2 sensors, we present concurrent, high-frequency (<30 min resolution) CO2 concentration and discharge data collected from five catchments across Canada, UK, and Fennoscandinavia to explore concentration-discharge dynamics; we also consider the relative importance of high flows to lateral aquatic CO2 export. The catchments encompassed a wide range of mean CO2 concentrations (0.73–3.05 mg C L−1) and hydrological flow regimes from flashy peatland streams to muted outflows within a Finnish lake system. In three of the catchments, CO2 concentrations displayed clear bimodal distributions indicating distinct CO2 sources. Concentration-discharge relationships were not consistent across sites with three of the catchments displaying a negative relationship and two catchments displaying a positive relationship. When individual high flow events were considered, we found a strong correlation between both the average magnitude of the hydrological and CO2 response peaks, and the average response lag times. An analysis of lateral CO2 export showed that in three of the catchments, the top 30% of flow (i.e., flow that was exceeded only 30% of the time) had the greatest influence on total annual load. This indicates that an increase in precipitation extremes (greater high-flow contributions) may have a greater influence on the flushing of CO2 from soils to surface waters than a long-term increase in mean annual precipitation, assuming source limitation does not occur.
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| 7. |
- Eklöf, Karin, et al.
(författare)
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Formation of mercury methylation hotspots as a consequence of forestry operations
- 2018
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 613-614, s. 1069-1078
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Tidskriftsartikel (refereegranskat)abstract
- Earlier studies have shown that boreal forest logging can increase the concentration and export of methylmercury (MeHg) in stream runoff. Here we test whether forestry operations create soil environments of high MeHg net formation associated with distinct microbial communities. Furthermore, we test the hypothesis that Hg methylation hotspots are more prone to form after stump harvest than stem-only harvest, because of more severe soil compaction and soil disturbance. Concentrations of MeHg, percent MeHg of total Hg (THg), and bacterial community composition were determined at 200 soil sampling positions distributed across eight catchments. Each catchment was either stem-only harvested (n = 3), stem-and stump-harvested (n = 2) or left undisturbed (n = 3). In support of our hypothesis, higher MeHg to THg ratios was observed in one of the stump-harvested catchments. While the effects of natural variation could not be ruled out, we noted that most of the highest % MeHg was observed in water-filled cavities created by stump removal or driving damage. This catchment also featured the highest bacterial diversity and highest relative abundance of bacterial families known to include Hg methylators. We propose that water-logged and disturbed soil environments associated with stump harvest can favor methylating microorganisms, which also enhance MeHg formation.
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| 8. |
- Gebrehiwot, Solomon, et al.
(författare)
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Hydrological characterization of watersheds in the Blue Nile Basin, Ethiopia
- 2011
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Ingår i: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 15:1, s. 11-20
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Tidskriftsartikel (refereegranskat)abstract
- Thirty-two watersheds (31-4350 km(2)), in the Blue Nile Basin, Ethiopia, were hydrologically characterized with data from a study of water and land resources by the US Department of Interior, Bureau of Reclamation (USBR) published in 1964. The USBR document contains data on flow, topography, geology, soil type, and land use for the period 1959 to 1963. The aim of the study was to identify watershed variables best explaining the variation in the hydrological regime, with a special focus on low flows. Moreover, this study aimed to identify variables that may be susceptible to management policies for developing and securing water resources in dry periods. Principal Component Analysis (PCA) and Partial Least Square (PLS) were used to analyze the relationship between five hydrologic response variables (total flow, high flow, low flow, runoff coefficient, low flow index) and 30 potential explanatory watershed variables. The explanatory watershed variables were classified into three groups: land use, climate and topography as well as geology and soil type. Each of the three groups had almost equal influence on the variation in hydrologic variables (R-2 values ranging from 0.3 to 0.4). Specific variables from within each of the three groups of explanatory variables were better in explaining the variation. Low flow and low flow index were positively correlated to land use types woodland, dense wet forest and savannah grassland, whereas grazing land and bush land were negatively correlated. We concluded that extra care for preserving low flow should be taken on tuffs/basalts which comprise 52% of the Blue Nile Basin. Land use management plans should recognize that woodland, dense wet forest and savannah grassland can promote higher low flows, while grazing land diminishes low flows.
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| 9. |
- Jingying, Xu, 1984-, et al.
(författare)
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Mercury methylating microbial communities of boreal forest soils
- 2019
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- The formation of the potent neurotoxic methylmercury (MeHg) is a microbially mediated process that has raised much concern because MeHg poses threats to wildlife and human health. Since boreal forest soils can be a source of MeHg in aquatic networks, it is crucial to understand the biogeochemical processes involved in the formation of this pollutant. High-throughput sequencing of 16S rRNA and the mercury methyltransferase, hgcA, combined with geochemical characterisation of soils, were used to determine the microbial populations contributing to MeHg formation in forest soils across Sweden. The hgcA sequences obtained were distributed among diverse clades, including Proteobacteria, Firmicutes, and Methanomicrobia, with Deltaproteobacteria, particularly Geobacteraceae, dominating the libraries across all soils examined. Our results also suggest that MeHg formation is linked to the composition of also non-mercury methylating bacterial communities, likely providing growth substrate (e.g. acetate) for the hgcA-carrying microorganisms responsible for the actual methylation process. While previous research focused on mercury methylating microbial communities of wetlands, this study provides some first insights into the diversity of mercury methylating microorganisms in boreal forest soils.
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| 10. |
- Lucas, Richard, et al.
(författare)
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A meta-analysis of the effects of nitrogen additions on base cations : Implications for plants, soils, and streams
- 2011
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Ingår i: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 262:2, s. 95-104
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Forskningsöversikt (refereegranskat)abstract
- The dominant base cations (BC: i.e., Ca(2+), Mg(2+), K(+), and Na(+)) are important in buffering soil and water acidity in both terrestrial and aquatic ecosystems. Ca(2+)., Mg(2+), and K(+) are also important in many plant physiological functions. Because BC availability is affected by changes in the nitrogen (N) cycle, we conducted a meta-analysis of previously published data to determine if N fertilization alters the availability of BC in terrestrial and stream ecosystems across biomes. We include data from 107 independent studies published in 62 different articles, taking a holistic perspective on BC by examining their responses to added N in plant foliage, bulk soil, soil solution, and stream water. Our results suggest N fertilization may accelerate BC loss from terrestrial ecosystems over time periods less than five years. We found that N additions resulted in an overall 24% decrease in the availability of exchangeable Ca(2+), Mg(2+), and K(+) in the bulk soil of boreal forest, temperate forest, and grassland biomes. Collectively, responses of BC in boreal forest, temperate forest, tropical forest, and grassland biomes increased following N fertilization by about 71% in soil solution and 48% in stream waters. Additionally, BC responses in foliage decreased in boreal forest and temperate forest biomes following N additions over time periods less than five years, but there were no significant changes over longer time periods. Despite large short-term shifts in BC responses following N additions, we did not find evidence of widespread negative impacts on ecosystems over time periods greater than five years. This analysis suggests effects of N addition on the availability of exchangeable BC may diminish over time. Although the effects on BC can be substantial over periods less than five years, there is little available evidence that N fertilization has had large-scale detrimental effects on the availability of BC needed for plant growth within terrestrial or aquatic ecosystems.
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