Thesis (M.S.) in Ecology and Environmental Science--University of Maine, 2006. / Includes vita. Includes bibliographical references (leaves 63-69).

Forty-five lakes in Killarney Provincial Park and the surrounding area in south-central Ontario, Canada, were sampled for crustacean zooplankton and water chemistry in the summer of 2005. For each of the lakes, we had historic data from peak-acidification in the 1970s and post-acidification periods in 1990 and 2000. Situated among the orthoquartzite ridges of the La Cloche Mountains in and near Killarney Provincial Park, many of these lakes were acidified during the mid-1900s owing to extensive mining and smelting activities in nearby (40-60 km) Sudbury, Ontario. There is large variation in the geochemistry of the soils and the bedrock within the park. As a result, these freshwater lakes have varying degrees of acidification, ranging from being heavily acidified (pH < 4.5) to others that were buffered from the effects of acidic deposition. With over 90% reductions in sulphur dioxide smelter emissions over the past 30 years and the present, many lakes in the Sudbury region are starting to show strong evidence of chemical recovery. Despite significant increases in lake water pH, there is limited evidence of biological recovery. A variety of univariate and multivariate metrics, as well as variation partitioning, were used to examine recovery on a lake-by-lake basis and on a regional scale. Our results revealed only moderate recovery of crustacean zooplankton communities despite improvements in water quality. Some lakes increased in zooplankton richness while others decreased compared to richness during peak acidification. Shifts in community composition from a damaged state toward those typical of circum-neutral lakes were observed for lakes that have chemically recovered. The lack of chemical recovery is believed to be impeding biological recovery of many lakes. Biological resistance and dispersal limitation do not appear to be hindering biological recovery. Other stressors such as the invasion by the predatory zooplankton Bythotrephes and climate change may delay biological recovery in the coming years. Future recovery of Killarney Park lakes will require further chemical recovery for biological recovery to become complete. / Thesis (Master, Biology) -- Queen's University, 2007-09-24 22:33:35.058

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Empirical algorithms are developed using high-quality GO-SHIP hydrographic measurements of commonly measured parameters (temperature, salinity, pressure, nitrate, and oxygen) that estimate pH in the Pacific sector of the Southern Ocean. The coefficients of determination, R-2, are 0.98 for pH from nitrate (pH(N)) and 0.97 for pH from oxygen (pH(Ox)) with RMS errors of 0.010 and 0.008, respectively. These algorithms are applied to Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) biogeochemical profiling floats, which include novel sensors (pH, nitrate, oxygen, fluorescence, and backscatter). These algorithms are used to estimate pH on floats with no pH sensors and to validate and adjust pH sensor data from floats with pH sensors. The adjusted float data provide, for the first time, seasonal cycles in surface pH on weekly resolution that range from 0.05 to 0.08 on weekly resolution for the Pacific sector of the Southern Ocean.

The objectives achieved in this thesis are: (1) to develop a new method for measuring the most important acid buffering mechanism within a soil ecosystem-mineral weathering and (2) to test a soil acidification simulation model against actual field data to determine which soil acidifying or buffering mechanisms seem to be understood and which mechanisms need more detailed analysis. First, a new method was developed that allows for quantification of H$ sp+$ consumption due to weathering and H$ sp+$ consumption due to cation exchange. Initial results yield mineral weathering rates that are well within the range of results obtained by other workers. This technique permits the analysis of multiple soil samples in a relatively short time, allowing for better quantification of spatial variability of mineral weathering within a soil ecosystem. Secondly, it was demonstrated that the acid simulation model generally underestimates soil chemistry values for pH, base cation saturation and soil solution base cations, and overestimates soil solution nitrate concentrations. Problems with obtaining accurate measurements of atmospheric dry deposition, a lack of data on cycling of nutrient elements and the absence of a sub-model to deal with the accumulation and mineralization of organic matter are reasons thought to explain the differences between model and field results.

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Calcium (Ca) depletion and increased bioavailability of aluminum (Al) are potential consequences of soil acidification caused by acidic deposition and other anthropogenic factors. Tree declines are associated with base cation depletion and increased Al toxicity in forest soils in North America, Europe, and Asia. Changes in soil Ca and Al availability may lead to increased oxidative stress and disruptions in carbohydrate relationships in forest trees, as well as to substantial alterations in the capacity for enzymatically controlled processes of decomposition and mineralization in forest soils. Assessments were made to determine if forest systems are prone to disruption associated with altered Ca and Al bioavailability. Foliar elemental concentrations, foliar antioxidant enzyme activities, foliar and woody shoot carbohydrates were measured in sugar maple (Acer saccharum, Marsh.), and soil extracellular enzyme activities (EEA) were assayed at a long-term nutrient perturbation study (NuPert) in the Hubbard Brook Experimental Forest, New Hampshire, USA. Treated plots received Ca to increase soil Ca above ambient depleted levels or Al to further reduce Ca availability. Additions of Ca to soil are associated with greater Ca concentrations in foliage compared to leaves from trees from control and Al-addition plots. Soil Aladditions are associated with lower foliar phosphorus concentrations in comparison with foliage from trees in Ca-addition plots. Additions of Al to soil are associated with higher antioxidant enzyme (glutathione reductase and ascorbate peroxidase) activities in foliage and lower shoot sugar (total sugars, sucrose, glucose and fructose) concentrations relative to trees in Ca-addition and control plots. Al accumulations in distal tissues likely triggered toxicity responses reported for leaves and stems. Soil EEA results highlight treatment-induced alterations to soil processes. Across soil enzyme systems, EEA levels are greatest in Al-addition soils in fall, but are elevated in Caaddition soils in spring compared with ambient conditions. Seasonal differences in EEA levels suggest a differential influence of soil treatments on specific soil communities. Within this native, mature northern hardwood forest, early indications of response in foundation species to Ca and Al manipulation are detected including Al-induced oxidative stress and resulting carbohydrate irregularities in sugar maple trees, and substantial seasonal swings in soil EEA: processes that could foreshadow broader ecosystem alterations as anthropogenic disruptions of soil Ca and Al availability continue.

Soil drainage water solute chemical composition showed not only increased losses of inorganic N with increasing N input but also substantially increased organic N losses from the soil system. These losses are important for water bodies both from the eutrophication and acidification view points, and may also be relevant in the context of trace metal transport via chelation. Preliminary studies showed that physical parameters such as hydraulic conductivity, bulk density and porosity could be important to assessment of damage occurring due to acidic N pollution load. Reduced soil microbial activity was clearly demonstrated from peat micromorphological studies and decomposition experiments. The micromorphological studies showed the thickening of the porous surface horizon in grossly polluted areas, where the decomposition process is slowed significantly. Under these conditions, however, NH4+ and NO3- leaching from microcosms is reduced, with greater use being made by biota of atmospheric N inputs as N mineralisation decreases. Two biotic components were studied. Enchytraeid worms showed sensitivity to soil acidity in the long term. Mycorrhizal infection studies showed that increasing N input, especially in the form of NH4+, could be injurious even in the short to mid term. Both studies suggested that more attention is needed in this area. aSignificant accumulation of NH4+ in peat was found in this study. Toxicity effects of high NH4+-N to plants or microflora may be manifesting themselves via discouraging infection in the Calluna root system. New plant generation for high NH4+- N treatment was also poor. It is suggested that, among the N species in N inputs, NH4+ could be most damaging.