Watmough, Shaun

The Athabasca Oil Sands in Alberta, Canada is one of the largest point sources emitters of NOx in Canada and there

are concerns that elevated nitrogen (N) deposition will lead to widespread eutrophication impacts, including altered

species composition, similar to what has occurred in several parts of Europe. Atmospheric deposition rates as high as

25 kg N ha-1 yr-1 have been measured close to the industrial center. The role of the forest floor in regulating these

potential eutrophication effects was investigated following a 5-year enrichment study in which N was applied as

NH4NO3 above the canopy of a jack pine (Pinus banksiana Lamb) stand in northern Alberta close to Fort McMurray

at dosages ranging from 5 – 25 kg N ha-1 yr-1 in addition to background deposition of 2 kg N ha-1 yr-1. Chemical

analysis of lichen mats revealed that apical (upper) lichen tissue N concentration increased with treatment, as did the

necrotic tissue. When expressed as a pool, the fibric-humic (FH) material held the largest quantity of N across all

treatments due to its relatively large mass. Soil net N mineralization and net nitrification rates did not differ among N

inputs after five years of application. A 15N tracer applied to the forest floor showed that N is initially absorbed by the

apical lichen, FH material, and the foliage of the vascular plant Vaccinium myrtilloides in particular. After 2 years,

the FH 15N pool size was elevated and all other measured pools were depleted, indicating a slow transfer of N to the

FH material. Applied 15N was not detectable in mineral soil. The microbial functional gene ammonia monooxygenase

(amoA) was undetectable using PCR screening of mineral soil microbial communities in all treatments, and broad

fungal/bacterial qPCR assays revealed a weak treatment effect on fungal/bacterial ratios in mineral soil. This work

suggests that terricolous lichen mats, which form the majority of ground cover in upland jack pine systems, have a

large capacity to effectively retain elevated N deposition via the formation of stable humus.

Author Keywords: Biogeochemistry, Boreal Ecology, Lichen, Nitrogen Enrichment, Oil Sands

Atmospheric pollutant deposition poses a risk to ecosystem health; therefore, monitoring the spatial and temporal trends of deposition is integral to environmental sustainability. Although moss biomonitoring is a common method to monitor various pollutants in Europe, offering a cost-effective approach compared to traditional methods of monitoring, it is rarely used in Canada. The focus of this study was a spatial assessment of trace element deposition across a region with a known large-point source of emissions using the moss biomonitoring method. Moss tissues presented strong correlations with modelled deposition in the region, suggesting mosses are a valuable biomonitoring tool of trace element deposition, especially in regions dominated by large-point emission sources. Additionally, a moss species endemic to Canada was compared to commonly used moss species with results indicating this species (Isothecium stoloniferum) can be used reliably as a biomonitor. Moss biomonitoring is recommended as a compliment to fill in spatial gaps in current monitoring networks across the country.

Author Keywords: biomonitoring, bryophytes, Hylocomium splendens, moss, Pleurozium schreberi, trace elements

This study seeks to clarify the way in which the differing canopy characteristics among tree species influence the partitioning of precipitation, and therefore the source of water available for plant water uptake, in the Plastic Lake catchment near Dorset, ON. Three dominant tree species were compared: red oak (Quercus rubra), eastern white pine (Pinus strobus), and eastern hemlock (Tsuga canadensis). Above-canopy precipitation, throughfall, stemflow, and soil water content were monitored weekly from June 2016 until October 2016 and the 18O and 2H isotopic signatures of each were analyzed. Plant water and bulk soil water samples were also collected from five trees of each species at five stages of the growing season to compare the isotopic signature of xylem water to that of their surrounding soils. Both plant water and bulk soil water displayed evidence of isotopic fractionation; however, plant water was more depleted in δ2H and δ18O than bulk soil water. Water interacting with the tree canopies as throughfall and stemflow did not display significant evidence of isotopic fractionation. This suggests that the vegetation could have accessed an isotopically distinct source of water stored within the soil or that an unknown isotopic fractionation process occurred throughout this study.

Timber harvest can influence the rate of transfer of organic matter from the terrestrial catchment to streams, which may have both direct and indirect effects on in-stream nutrient pools and dynamics. In the interest of developing sustainable forestry practices, the continued study of the effects of forestry on nutrient dynamics in aquatic systems is paramount, particularly in sensitive nutrient-poor oligotrophic systems. The goal of this study was to investigate the impacts of harvest-related woody debris on stream nutrient status in streams located in the Canadian Shield region of south-central Ontario. Surveys showed greater large (> 10 cm) and small (< 10 cm) woody debris dry masses and associated nutrient pools in streams located in recently (2013) selectively harvested catchments, when compared with catchments not harvested for at least 20 years. Experimental releases of flagging tape underlined the importance of woody debris as a mechanism of coarse particulate organic matter (CPOM) retention. Sediment surveys showed a significant exponential decline in both OM content and nutrients associated with coarse sediment with distance upstream from debris dams. Laboratory leaching experiments suggest that fresh woody debris may be an important short-term source of water-soluble nutrients, particularly phosphorus and potassium. This study suggests that woody debris from timber harvest is both a direct and indirect source of nutrients, as trapped wood and leaves that accumulate behind debris dams can augment stream nutrient export over long time periods.

Author Keywords: nutrient leaching, nutrient pools, organic matter retention, selection harvest, southern Ontario, woody debris

The reliability and performance of four passive sampler membrane coatings specific to nitrogen dioxide (NO2) were evaluated through co-exposure at multiple Ontario Ministry of Environment and Climate Change (OMOECC) active monitoring stations. All four coatings performed relatively similar under a wide range of meteorological conditions, notably showing exposure-specific atmospheric uptake rates. Further, indoor and outdoor atmospheric concentrations of NO2 (a marker of traffic-related air pollution) were evaluated at multiple elementary schools in a high-density traffic region of Toronto, Ontario, using a Triethanolamine based passive sampler membrane coating. Samplers were also co-exposed at OMOECC active monitoring stations to facilitate calibration of exposure-specific atmospheric uptake rates. Indoor NO2 atmospheric concentrations were 40 to 50% lower than outdoor concentrations during the spring−summer and autumn−winter periods, respectively. In large cities such as Toronto (Population 2,700,000), the influence of a single major road on outdoor and indoor NO2 concentrations is predominantly masked by spatially-extensive high-density traffic.

Author Keywords: active sampler, membrane coating type, nitrogen dioxide, passive sampler, Toronto, traffic density

This study was designed to determine the geochemistry and potential toxicity of water draining a large slag pile in Sudbury, Ontario, which runs through a pond complex prior to entering Alice Lake. Slag leaching experiments confirmed slag is a source of sulphate, heavy metals (including Fe, Al, Ni, Co, Cu, Zn, Pb, Cr, Mn) and base cations (Ca, K, Mg, Na). Concentrations of most metals draining through slag in column experiments were similar to metal concentrations measured at the base of the slag pile, although base cations, S and pH were much higher, possibly because of water inputs interacting with the surrounding basic glaciolacustrine landscape. The increase in pH rapidly precipitates metals leading to high accumulation in the surface sediments. Away from the base of the pile, an increase in vegetation cover leads to an increase in DOC and nutrients and transport of metals with strong binding affinities (Cu). Total metal concentration in water and sediment exceed provincial water quality guidelines, particularly near the slag pile, however WHAM7 modeling indicated that the free metal ion concentration in water is very low. Nevertheless, toxicity experiments showed that water with greater concentrations of solutes collected close to the slag pile negatively impacts D. magna suggesting that water draining the slag pile can adversely impact biota in nearby drainage areas.

Author Keywords: geochemistry, heavy metals, leaching, non-ferrous slag, precipitation, toxicity

(MRC) in central Ontario was carried out to determine the range and spatial distribution of soil Ca weathering rates, and investigate the relationships between lake Ca and soil and catchment attributes. The MRC is acid-sensitive, and has a long history of impacts from industrial emission sources in Ontario and the United States. Small headwater catchments were sampled for soil and landscape attributes (e.g. elevation, slope, catchment area) at 84 sites. Soil Ca weathering rates, estimated with the PROFILE model, were low throughout the region (average: 188 eq/(ha·yr)) compared to global averages, and lower than Ca deposition (average: 292 eq/(ha·yr)). Multiple linear regression models of lake Ca (n= 306) were dominated by landscape variables such as elevation, which suggests that on a regional scale, landscape variables are better predictors of lake Ca than catchment soil variables.

Author Keywords: Calcium, Lakes, Regional assessment, Regression, Soils, Weathering

Phosphorus (P) is an essential macronutrient. In south-central Ontario, foliar P concentrations are low and studies have suggested that P may be limiting forest productivity. Current catchment mass balance estimates however, indicate that P is being retained suggesting that P should not be limiting to tree growth. Phosphorus deposition is measured using bulk deposition collectors, which are continuously open and therefore are subject to contamination by pollen and other biotic material with high P and potassium (K) concentrations and may therefore overestimate net P inputs to forested catchments. Average annual TP and K deposition at three long-term (1984 – 2013) monitoring sites near Dorset, Ontario ranged from 15 to 20 mg·m-2y-1 and 63 to 85 mg·m-2y-1, respectively, and was higher at Paint Lake compared with Plastic Lake and Heney Lake. Phosphorus and K in bulk precipitation were strongly positively correlated, but deposition patterns varied spatially and temporally among the three sites. Total phosphorus and K deposition increased significantly at Plastic Lake and decreased significantly at Paint Lake, but there was no significant trend in TP or K deposition at Heney Lake over the 30 year period. All sites, but especially Paint Lake, exhibited considerable inter-annual variation in TP and K deposition. To quantify the contribution of pollen, which represents an internal source of atmospheric P deposition, Durham pollen collectors during the spring and summer of 2014 were used. The three sites, Paint Lake, Heney Lake, and Plastic Lake had pollen deposition amounts of 5202 grains·cm-2, 7415 grains·cm-2, and 12 250 grains·cm-2, respectively in 2014. Approximately 83% of pollen deposition can be attributed to white pine and red pine that has a concentration of 3 mg·g-1 of P. It was estimated that pollen alone could account for up to one-third of annual bulk P deposition. Extrapolating winter P deposition values to exclude all potential biotic influences (insects, bird feces, leaves), indicates that bulk deposition estimates may double actual net P to forests, which has implications for long-term P availability, especially in harvested sites.

Author Keywords: Atmospheric Deposition, Phosphorus, Pine, Pollen, Potassium, South-Central Ontario

As part of a mandate to control the spread of Stratiotes aloides (WS; water soldier) in the Trent Severn Waterway, the Ministry of Natural Resources (MNR) created a management plan to eradicate WS. However, one of the biggest challenges in eradicating WS or any invasive aquatic plant is the ability to estimate the extent of its spread and detect new populations. While current detection methods can provide acceptable detection, these methods often require extensive time and effort. The purpose of this thesis was to assess the use optical properties of WS and WS exudates for detection, in order to improve on current detection methods. The optical properties of WS were sampled at three different sites during three different seasons (spring, summer, and fall) by a) randomly sampling tissue from WS and the local plant community at each site, and recording the reflectance properties in a laboratory setting b) collecting dissolved organic matter (DOM) samples from plant incubations and river water in the field. Significant differences in the reflectance properties of WS were observed among samples from different sites and different sampling times; however, changes in fluorescence properties were only seasonal. Despite spatial differences in WS reflectance; WS was detectable using both hyperspectral and multispectral reflectance. When hyperspectral reflectance was used, significant differences between WS and the local plant community were found in June using two bands (i.e. bands 525 and 535, R 2 = 0.46 and 0.48, respectively). Whereas multispectral reflectance was significant different in October using the coastal and blue band. While WS produced a unique signal using both reflectance types, multispectral reflectance had a greater potential for detection. Its greater potential for detection was due to the reduced noise produced by background optical properties in October in comparison to June. DOM derived from WS was also characterized and compared with whole-river DOM samples in order to find unique markers for WS exudates in river samples. While similarities in DOM concentrations of WS exudates to Trent River water limited the ability to detect WS using compositional data, the ratio of C4/C5 components were compared in order to find components that were proportionally similar. Based on the results of this study multispectral and fluorescence techniques are better suited for the detection of a unique WS signature. The results derived from this work are intended to have practical applications in plant management and monitoring, DOM tracing, as well as remote sensing.

Author Keywords: Dissolved organic matter, Hyperspectral reflectance, Invasive species management, Multispectral reflectance, PARAFAC, Stratiotes aloides

Dissolved organic matter (DOM) is a mixture of molecules with dynamic structure and composition that are ubiquitous in aquatic systems. DOM has several important functions in both natural and engineered systems, such as supporting microorganisms, governing the toxicity of metals and other pollutants, and controlling the fate of dissolved carbon. The structure and composition of DOM determine its reactivity, and hence its effectiveness in these ecosystem functions.

While the structure, composition, and reactivity of riverine and marine DOM have been previously investigated, those of allochthonous DOM collected prior to exposure to microbes and sunlight have received scant attention. The following dissertation constitutes the first in-depth study of the structure, composition, and reactivity of allochthonous DOM at its point of origin (i.e. leaf leachates, LLDOM), as detected by measuring its size and optical properties. Concomitantly, novel chemometric methods were developed to interpret size-resolved data obtained using asymmetrical flow field-flow fractionation, including spectral deconvolution and the application of machine learning algorithms such as self-organizing maps to fluorescence data using a dataset of more than 1000 fluorescence excitation-emission matrices.

The size and fluorescence properties of LLDOM are highly distinct. Indeed, LLDOM was correctly classified as one of 13 species/sources with 92.5% accuracy based on its fluorescence composition, and LLDOM was distinguished from riverine DOM sampled from eight different rivers with 98.3% accuracy. Additionally, both fluorescence and size properties were effective conservative tracers of DOC contribution in pH-controlled mixtures of leaf leachates and riverine DOM over two weeks. However, the structure of LLDOM responded differently to pH changes for leaves/needles from different tree species, and for older needles. Structural changes were non-reversible.

Copper-binding strength (log K) differed for the different fluorescent components of DOM in a single allochthonous source by more than an order of magnitude (4.73 compared to 6.11). Biotransformation preferentially removed protein/polyphenol-like fluorescence and altered copper-binding parameters: log K increased from 4.7 to 5.5 for one fluorescent component measured by fluorescence quenching, but decreased from 7.2 to 5.8 for the overall DOM, as measured using voltammetry. The complexing capacity of DOM increased in response to biotransformation for both fluorescent and total DOM. The relationship between fluorescence and size properties was consistent for fresh allochthonous DOM, but differed in aged material.

Since the size and fluorescence properties of LLDOM are strikingly different from those of riverine DOM, deeper investigation into transformative pathways and mixing processes is required to elucidate the contribution of riparian plant species to DOM signatures in rivers.

Author Keywords: Analytical chemistry, Chemometrics, Dissolved organic matter (DOM), Field-flow fractionation, Fluorescence spectroscopy, Parallel factor analysis (PARAFAC)