Koprivnjak, Jean-François

Phosphorus is the growth-limiting nutrient in freshwater environments. Dissolved organic phosphorus (DOP) refers to phosphorus within dissolved organic matter (DOM). Much of DOP is bioavailable, but it is poorly understood due to its complexity. This thesis explores the export DOP to Lake Erie from its tributaries, by investigating its speciation and concentration seasonally through weekly sampling of two tributaries and spatially across a river to lake transect. The rivermouth was a site of rapid transition, with lower concentrations of DOP in the lake than in the river and a greater proportion of P as DOP in the lake. Phosphomonoesters and aromatic DOM were coupled in the medium-sized Grand River, but not in the Upper Great Lakes-influenced Detroit River. Phosphodiesters and highly processed DOM were coupled in the Detroit River, but only during periods of low terrestrial inputs. Finally, we found that DOP is a large contributor to tributary phosphorus exports.

Author Keywords: dissolved organic matter, dissolved organic phosphorus, enzymatic hydrolysis, Lake Erie, nutrient export, rivermouth

In this study, twenty lake catchments surrounding Iqaluit, Baffin Island, were assessed for trace element concentrations (Al, As, Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Se, THg, V, Zn) in lake water, catchment soil, lake sediment, and moss (Hylocomium splendens). Additionally, the sources of each trace element were determined through the positive matrix factorization (PMF) model and enrichment factors (only in moss). Geogenic trace elements had the highest median concentrations (Fe>Al>Mn) throughout the study media and across the study catchments. Anthropogenic trace elements had the lowest median concentrations (Pb>As>Cd>THg) across the lake catchments, which were generally several orders of magnitude lower compared to geogenic elements. The PMF model identified trace elements associated with geogenic or anthropogenic sources, i.e., THg (47%), Cd (40%), Zn (34%), and Al (27%) were identified as originating from industrial emission sources deposited onto lakes because they accounted for a large proportion within the model.

Author Keywords: Arctic lake catchments, Biomonitoring, Enrichment factors, Positive matrix factorization model, Trace elements, Water chemistry

Chromophoric dissolved organic matter (CDOM), a chemically diverse family of organic compounds defined by their ability to absorb ultraviolet and visible light, is a critical constituent of numerous environmental systems, including freshwater lakes. Industrial operations in the Athabasca Oil Sands Region (AOSR, Alberta, Canada) are major sources of acidic inorganic gases and organic contaminants to the atmosphere, the subsequent deposition of which posed the potential to alter the composition of natural CDOM within surrounding lake surface-waters. The objective of this thesis was to determine if OS sources measurably impacted CDOM quality within 50 regionally monitored acid sensitive lakes by means of a) altered acid-base chemical processes or b) industrial atmospheric CDOM inputs. Ultraviolet-visible light spectroscopy and excitation emission matrix (EEM) fluorescence spectroscopy were applied to characterize CDOM within regional lake surface-waters to identify the primary sources (e.g., natural, anthropogenic) and process (e.g., acid-base chemistry) influencing chromophoric organic matter quality. These spectroscopic techniques were further used to evaluate industrial CDOM within atmospheric aerosols and deposition to assist with the identification of industrial CDOM within lake waters. Spectroscopic analysis of regional lake surface-water found weak associations between CDOM and acid-base variables, suggesting that acid inputs from OS sources would have limited influence over surface-water chromophoric organic matter. A distinct fluorescent component (i.e., fluorophore) measured within the lake samples (C3) displayed decreasing emission intensity as a function of distance from OS sources and positive correlations with surface-water polycyclic aromatic compounds, implying industrial influence. Spectral similarity between C3 and industrial fluorophores observed from regional aerosol and atmospheric deposition samples further confirmed the lake fluorophore was linked to OS sources. This research suggests that EEM fluorescence spectroscopy could be used as a cost-effective technique to detect industrial pollution within lake surface-waters throughout the AOSR.

Author Keywords: atmospheric brown carbon, atmospheric deposition, atmospheric pollution, dissolved organic matter, fluorescence spectroscopy, lake chemistry

In situ chlorophyll sensors are beneficial for monitoring of long-term impacts of algal blooms and accessing water quality issues in bodies of water. However, more research is needed to validate their efficacy and understand how environmental conditions can influence sensor measurements. I assessed the performance of an in situ chlorophyll sensor under controlled environmental conditions and used the same sensor to collect vertical phytoplankton patterns in south-central Ontario boreal lakes. The performance of the sensor was assessed by examining the precision of chlorophyll measurements and determining the suitable timing length that would produce precise results. In general, the sensor was relatively insensitive to conditions under lower algal concentrations and the decent of the sensor should be slowed for vertical lake profiling in lakes with higher algal biomass. Most variation resulted from the movement of particle bound algal cells. We described chlorophyll profile characteristics including surface chlorophyll levels and chlorophyll peak depth and width and investigated the relationships of these features with environmental controls. The lakes showed a typical chlorophyll profile of low phytoplankton biomass lakes. Our results showed that dissolved organic carbon was a strong predictor of epilimnetic biomass while light attenuation and dissolved organic carbon were both strong predictors of peak depth. Light attenuation and surface area were small but significant predictors of peak width. We acknowledged that any uncertainties in sensor chlorophyll readings were not an issue in our lakes due to the overall low chlorophyll biomass.

Author Keywords: chlorophyll, chlorophyll fluorescence, in situ profiling, lakes, phytoplankton biomass, water quality 

Phosphorus is the growth-limiting nutrient in freshwater environments. Dissolved organic phosphorus (DOP) refers to phosphorus within dissolved organic matter (DOM). Much of DOP is bioavailable, but it is poorly understood due to its complexity. This thesis explores the export DOP to Lake Erie from its tributaries, by investigating its speciation and concentration seasonally through weekly sampling of two tributaries and spatially across a river to lake transect. The rivermouth was a site of rapid transition, with lower concentrations of DOP in the lake than in the river and a greater proportion of P as DOP in the lake. Phosphomonoesters and aromatic DOM were coupled in the medium-sized Grand River, but not in the Upper Great Lakes-influenced Detroit River. Phosphodiesters and highly processed DOM were coupled in the Detroit River, but only during periods of low terrestrial inputs. Finally, we found that DOP is a large contributor to tributary phosphorus exports.

Author Keywords: dissolved organic matter, dissolved organic phosphorus, enzymatic hydrolysis, Lake Erie, nutrient export, rivermouth

In this study, twenty lake catchments surrounding Iqaluit, Baffin Island, were assessed for trace element concentrations (Al, As, Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Se, THg, V, Zn) in lake water, catchment soil, lake sediment, and moss (Hylocomium splendens). Additionally, the sources of each trace element were determined through the positive matrix factorization (PMF) model and enrichment factors (only in moss). Geogenic trace elements had the highest median concentrations (Fe>Al>Mn) throughout the study media and across the study catchments. Anthropogenic trace elements had the lowest median concentrations (Pb>As>Cd>THg) across the lake catchments, which were generally several orders of magnitude lower compared to geogenic elements. The PMF model identified trace elements associated with geogenic or anthropogenic sources, i.e., THg (47%), Cd (40%), Zn (34%), and Al (27%) were identified as originating from industrial emission sources deposited onto lakes because they accounted for a large proportion within the model.

Author Keywords: Arctic lake catchments, Biomonitoring, Enrichment factors, Positive matrix factorization model, Trace elements, Water chemistry

In situ chlorophyll sensors are beneficial for monitoring of long-term impacts of algal blooms and accessing water quality issues in bodies of water. However, more research is needed to validate their efficacy and understand how environmental conditions can influence sensor measurements. I assessed the performance of an in situ chlorophyll sensor under controlled environmental conditions and used the same sensor to collect vertical phytoplankton patterns in south-central Ontario boreal lakes. The performance of the sensor was assessed by examining the precision of chlorophyll measurements and determining the suitable timing length that would produce precise results. In general, the sensor was relatively insensitive to conditions under lower algal concentrations and the decent of the sensor should be slowed for vertical lake profiling in lakes with higher algal biomass. Most variation resulted from the movement of particle bound algal cells. We described chlorophyll profile characteristics including surface chlorophyll levels and chlorophyll peak depth and width and investigated the relationships of these features with environmental controls. The lakes showed a typical chlorophyll profile of low phytoplankton biomass lakes. Our results showed that dissolved organic carbon was a strong predictor of epilimnetic biomass while light attenuation and dissolved organic carbon were both strong predictors of peak depth. Light attenuation and surface area were small but significant predictors of peak width. We acknowledged that any uncertainties in sensor chlorophyll readings were not an issue in our lakes due to the overall low chlorophyll biomass.

Author Keywords: chlorophyll, chlorophyll fluorescence, in situ profiling, lakes, phytoplankton biomass, water quality 

The following study measured dissolved organic carbon (DOC) and total mercury (THg) concentrations in acid sensitive lakes in the Republic of Ireland. Sixty-eight upland lakes and 48 lowland lakes were sampled for DOC; the upland lakes were additionally sampled for THg. Spatial variability of DOC was explained by regional precipitation and soil organic matter. A subset of lakes was tested for long-term trends and in contrast to reports of rising DOC in European surface waters, changes in DOC were minor. Spatial variability in THg was explained by DOC and organic matter aromaticity. Long-term THg concentrations increased, likely caused by inputs of terrestrial THg. A subset of lakes was sampled for sediment and soil and the results suggested soils drove THg variation in lake water and sediment. Lake water and sediment THg was low and consistent with background regions, while soil THg was relatively high due to high organic content.

Author Keywords: Dissolved Organic Carbon, Lakes, Organic Matter, Soil, Total Mercury, Water

Ionizing organic chemicals are recognized as constituting a large fraction of the organic chemicals of commerce. Many governments internationally are engaged in the time-consuming and expensive task of chemical risk assessment for the protection of human and environmental health. There are standard models that are consistently used to supplement experimental and monitoring data in such assessments of non-ionizing organics by both government regulators and industry stakeholders. No such standard models exist for ionizing organics. Equilibrium distribution models, the foundational equations within multimedia environmental fate models for non-ionizing organics, were developed for the standard series of biphasic systems: air-water, particle-water, air-particle and organic-aqueous phases within living tissue. Multiple chemical species due to the ionization reaction were considered for each system. It was confirmed that, under select conditions, the properties of the neutral parent are sufficient to predict the overall distribution of the organic chemical. Complications due to biotransformation and paucity of identifiable equilibrium distribution data for ionizing organics limited the development of the model for living tissues. However, the equilibrium distributions of ionizing organics within this biotic system were shown to correlate with the abiotic sediment-water system. This suggests that the model developed for particle-water systems should be adaptable to the biotic system as model input and test data become available. Observational data for soil- and sediment- water systems, i.e., particle-water systems, allowed the development of a primarily non-empirical distribution equation for mono-protic acids; this model was almost entirely theoretically derived. The theoretical approach to model development allowed a quantitative assessment of the role of the neutral ion pair, resulting from the complexation of the organic anion with metal cations. To demonstrate the model's potential usefulness in governmental screening risk assessments, it was applied to a broad range of mono-protic organics including drugs and pesticides using standard property estimation software and generic inputs. The order-of-magnitude agreement between prediction and observation typical of the existing models of non-ionizing organics was generally achieved for the chemicals tested. The model was sensitive to the octanol-water partition coefficient of the most populous species. No calibration set was used in the development of any of the models presented.

Author Keywords: bioconcentration, chemical equilibrium, environmental modelling, ionizing organic, sorption

Maximum permitted SO2 emissions from an aluminum smelter in Kitimat, B.C., increased after modernization in 2015. An increase in acidic deposition can potentially acidify forest soils. Monitoring was conducted at two long-term soil monitoring plots at near (7 km) and far (41 km) sites downwind from the smelter. Change in soil properties was assessed between 2015 and 2018: for the near plot, there was significant decrease in pH and exchange acidity; far plot soils exhibited significant decrease of base cations and exchange acidity in the 0–5 cm layer only. The average total SO42- deposition at near and far plots were estimated to be between 8.2–12.1 and 6.7–7.4 kg/ha/yr, respectively. It was concluded no soil acidification was detected. Observed changes were attributed to measured differences in organic matter, likely influenced by sampling difficulty and measurement process discrepancies. Estimated SO42- deposition levels pose no risk to soil base cation depletion.

Author Keywords: acid forest soils, acidic deposition, aluminum smelter, exchangeable base cations, long-term monitoring, minimum detectable change