Thesis (M.S.)--University of Wisconsin--Madison, 1970. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Peats and organic-rich soils are a key part of the global carbon (C) cycle due to their sequestration and storage of atmospheric C as organic matter. Atmospheric deposition as a result of human activities has led to increased inventories of lead (Pb) and mercury (Hg) in UK peats and organic-rich soils. Ombrotrophic peat bogs, which receive all their nutrients and pollutants from the atmosphere, provide a historic record of Pb and Hg deposition within their solid phase. Organic-rich forest soil systems can also act as sinks for anthropogenic Pb but vertical transport of Pb can distort these temporal records. The long-term outlook may, however, be affected by processes which lead to decomposition of organic matter e.g. drying out of peatlands and soils due to climatic change, since these may release Pb into the aqueous phase and volatile Hg to the atmosphere. The associations and speciation of Pb and Hg within peats and organic-rich soils are not well understood but are key to understanding both the potential for release of these pollutants into other environmental compartments and the risks to ecosystems and human health posed by such a release. Investigation of 4 sites in central Scotland showed that, depending on vertical depth, ~40-99% of Pb in ombrotrophic peat was in association with large (0.22 μm – 100 kDa) humic molecules. Near-surface regions where intact plant material had not yet undergone complete humification showed the lowest proportion of Pb-humic association. Historical Pb deposition was retained to similar degrees across each site with recorded inventories to 1986 of 0.340-0.561 g m-2. However, perturbation of the 206Pb/207Pb isotope ratio profile at Glentress forest indicated that limited migration of petrol-sourced Pb may be occurring. Similarly, perturbation of the 210Pb profile at Auchencorth Moss, in addition to discrepancies in the apparent time period in which peak Pb deposition occurred, indicated that Pb may also be subject to migration within this ombrotrophic system. With respect to Hg, between-site differences in speciation were observed. For example, Hg2+ represented < 25% of the total Hg species in the top 10 cm of solid phase ombrotrophic peat but > 50% of the total in forest soil. In contrast, aqueous phase Hg was entirely in the inorganic form across all sites. The occurrence of a solid phase [Hg] peak in layers corresponding to the ~1955 height of coal burning, in addition to the narrow range of peatland Hg inventories to 1950 (2.20-3.23 g m-2) provide evidence that Hg deposition records may be maintained in organic-rich systems to a greater degree than previously assumed. Differences observed in the associations of Pb and the speciation of Hg between the surface vegetation of ombrotrophic bogs and the underlying peat suggests that plants play an integral role in the biogeochemical behavior and sequestration of Pb and Hg in these terrestrial systems.

An understanding of the dominant processes controlling streamwater chemistry is critical for the development of a regional water quality model. The relative importance of a variety of catchment characteristics in determining streamwater chemistry in the English Lake District is investigated in this thesis. Fifty-five streams were sampled on a bimonthly basis over the period May 1996 through March 1997. Rock samples were analysed using X-ray fluorescence analysis. The major- and trace element geochemical data was used to classify the suite into six rock types. The geochemical data was also used to establish weathering patterns, which suggested that greywackes and lithic arenites weather the easiest, andesites and dacites exhibit heterogeneous weathering and the metamorphosed slate and granite are the most resistant to weathering. Forty-one (75%) of the streams can be considered sensitive to acidification on the basis of their alkalinity and thirty-eight (69%) can be considered sensitive to acidification on the basis of their calcium concentrations. Statistical analyses showed that flow-weighted concentrations of alkalinity and base cations were lowest in the catchments with resistant bedrock, thin or peaty soils, at high altitudes or receiving relatively high loads of sulphur and nitrogen deposition. A multiple regression model incorporating some of these factors provided a fairly good approximation of alkalinity concentrations on a spatial (R2 value of 56%) and temporal scale (R2 value of 49%). The predicted alkalinity was within 50 Ileq rl of the observed (simulated) values for 77% of the sites. Although the model has a fairly good predictive capability, its spatial and temporal applicability outside the study area is an unknown quantity. To satisfy the needs of policy makers and the hydrological community, the model needs to predict alkalinity with a high degree of accuracy in a variety of study areas. This has not been tested as yet, however, the variables used in the final model are not unique to the Lake District or the 1990's and therefore the model may prove to be an extremely useful tool indeed.

Extensive drainage of UK peatlands has been associated with dehydration of the peat, an increase in water colour and a loss of carbon storage. Water colour has been found to be proportional to the concentration of fluvial dissolved organic carbon (DOC) (McKnight et al. 1985). It has been considered that the blocking of drainage channels represents a means of peat restoration and a way of reducing DOC losses to surface waters. This study aimed to assess the effectiveness of drain blocking at both an individual drain scale and at a larger catchment scale (up to 1km2). The effect of external parameters become more pronounced as the DOC record is examined at larger scales. The catchment is an open system and water chemistry will be influenced by mixing with water from other sources. Also it is likely that at some point the drains will cut across slope leading to the flow of any highly coloured water down slope, bypassing the blockages, and entering the surface waters downstream. Degradation of DOC will occur naturally downstream due to the effects of light and microbial activity. There is, consequently, a need to examine the wider effects of drain blocking at a catchment scale to ensure that what is observed for one drain transfers to the whole catchment. A series of blocked and unblocked catchments were studied in Upper Teesdale, Northern England. A detailed sampling programme of stream water, soil water and run off was undertaken in which a series of drains were studied in the 12 months prior to and post blocking. Water table depth, flow and weather parameters were also monitored. This study could not find a significant decline in DOC concentration at zero or first order scale post blocking; however a small yet significant decline of 2.5% in DOC concentration relative to the control catchment was recorded at the first order scale. A decrease in DOC concentration is recorded as water flows from the zero to the first order in the same catchment. The study found that the effects of DOC degradation in the catchments were very small and that DOC degradation could not solely explain the decrease in DOC concentration seen from zero to first order drains indicating the importance of dilution effects in the catchments. The blocking of peat drains does significantly decrease the export of DOC which is largely achieved by decreasing water yield. The size of the DOC export reduction caused by drain blocking is seen to decrease as scale increases providing evidence for the existence of bypass flow around the zero order drain blockages. Blocking was found to have little impact on the level of the catchment water table. This can be explained by the peat bog being naturally very wet before intervention such that when blocking did occur the soil had little capacity to take in additional water. Water yield, however, is seen to decrease post blocking indicating that water and potentially DOC is being lost from the system. Principle component analysis and event analysis were performed on the hydrological and chemical data in order to trace and define this missing component of the water balance yet the analysis found that the water chemistry in the study catchment can be defined by a relatively simple mixing trend. As such this missing water remains undefined. The presence of bypass flow and water mixing will reduce the efficiency of any drain blocking and have wider implications for upland management and its practitioners.

High nitrous oxide (N2O) emission potential has been identified in hemiboreal forest on drained Histosols. However, the environmental factors regulating the emissions were unclear. To investigate the importance of different factors on the N2O emission, a modeling approach was accomplished, using CoupModel with Monti-Carlo based multi-criteria calibration method. The model was made to represent a forest on drained peat soil in south-west Sweden where data of fluxes combined with soil properties and plant conditions were used. The model outcome was consistent with measurements of abiotic (soil temperature, net radiation, groundwater level and soil moisture) and biotic responses (net ecosystem exchange and soil respiration). Both dynamics and magnitude of N2O emissions were well simulated compared to measurements (8.7 ± 2.1 kg N/ha/year). The performance indicators for an ensemble of accepted simulations of N2O emission dynamics and magnitudes were correlated to calibrated parameters related to soil anaerobic fraction and atmospheric nitrogen deposition (correlation coefficient, r ≥ 0.4). A weak correlation with N2O emission dynamics was also found for biotic responses (r ≥ 0.3). However, the ME of simulated and measured N2O emissions was better correlated to the ME of soil moisture (r = -0.6), and also to the ME of both the soil temperature (r = 0.53) and groundwater level (r = -0.7). Groundwater level (range from -0.8 m to -0.13 m) was identified as the most important environmental factor regulating the N2O emissions for present forest soil. Profile analysis indicated that N2O was mainly produced in the deeper layers (≥ 0.35 m) of the soil profile. The optimum soil moisture for N2O production was around 70%.

Kunskapen kring svensk torvmarksbeskogning är undermålig. En kunskapslucka som till stor del beror på att torvmark tidigare bedömts som ointressant mark i samband med skogsproduktion. Detta beror mycket på det svenska regelverkets restriktioner mot markavvattning och gödsling samt miljöaspekterna som berörs och den aktivare skötsel som krävs. Det ökade behovet av skogsråvara gör att skogsbruket söker nya marker där torvmarken har potential att etableras för skogsproduktion. Studien är en kunskapssammanställning som lyfter fram kunskap kring skogsbruk på svensk torvmark med fokus på föryngringsprocessen. Finland använder torvmarker i skogsbruket på ett sofistikerat sätt. I studien jämförs Sveriges förutsättningar för skogsproduktion på torvmark med Finlands skötselprogram, en jämförelse som går att använda som en fingervisning till vilka föryngringsmetoder som lämpar sig i Sverige. Studien rymmer även en mindre fältstudie på torvmark som visar på tydliga indikationer av näringsbrist i marken och vikten av en korrekt utförd gödslingsåtgärd. / The knowledge of forestry on Swedish peatland is insufficient. The knowledge gap is largely due to peatland previously being considered unsuitable land in connection with the forest. This is highly due to the Swedish regulatory restrictions on land drainage and fertilization, but also due to the environmental aspects involved and proactive maintenance required. The increased demand for forest products has allowed forestry to seek alternatives, where peat soil has the potential to be established for forest production. The study is a compilation of knowledge that emphasizes the knowledge of forestry on Swedish peatland with focus on the rejuvenation process. Finland uses peatland forestry in a sophisticated way. The study compares Sweden's prospects for forestry on peatland with Finland's maintenance program, a comparison that can be used as a pointer to which rejuvenation methods are suitable in Sweden. The study also contains a field study on peatland showing clear signs of nutrient deficiency in the soil and the importance of correct fertilization.

Large areas of northern Sweden have been ditched to promote forest growth by draining wet soils and peatlands. These ditches have greatly added to length of Sweden’s stream and river network, but the ecological properties of these man-made aquatic environments is poorly understood. The aim of this thesis was to evaluate the extent to which forest ditches support benthic macroinvertebrate communities, test the factors might influence variation in these communities across ditches, and evaluate how these communities differ from those observed in more natural headwater streams. To do this, I analysed macroinvertebrate family richness and community composition from 16 sampling sites distributed across two ditch networks in northern Boreal Sweden. At each site, I also compiled information related to channel structure, water depth, and the upstream distance from more typical headwater streams. I then tested whether variation in community metrics among ditch sites was related to differences in local habitat properties as well in the spatial position of sites within the ditch network.  Finally, I used existing data from four headwater streams within the same broader catchment to evaluate how these communities compare with those observed in forest drainage ditches. Results showed that macroinvertebrate family richness and community composition varied among ditch sampling sites, but that these systems supported a range of aquatic taxa that are typically found in headwater streams.  Overall, family richness tended to increase among ditch sampling locations that had greater water depth at the time of sampling and that were located further downstream in the ditch network. In addition, sampling locations with mineral substrate tended to support communities with a greater representation of more sensitive aquatic orders when compared to sites dominated by peat sediments. Finally, while family richness was not significantly different between ditches and headwater streams, benthic communities in streams were dominated by different set of taxa that reflect greater flow velocity and better overall water quality conditions.  Overall, my results suggest ditches in the boreal forest landscape can support benthic communities that closely resemble what is observed in headwater streams. However, ditch habitats were also highly variable, with several sites indicating poor local habitat conditions for many benthic organisms.  Hydrological patterns, including water depth, but also unmeasured variables like flow velocity and the potential for seasonal drying likely play a key role in influencing the ecological properties of ditches in these landscapes.