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Water Quality Centre

Two scientists analyzing data shown on a monitor.

Water Quality Centre

Research

Numerous research projects rely on access to the Water Quality Centre. These research projects consist of two types: 1) development of innovative new techniques for analysis of organic and inorganic materials at isotopic, elemental and molecular scale; 2) applications of the new techniques in environmental studies, particularly in water quality research. Examples of some of these projects are:

Mercury Sources in Aquatic Ecosystems

(Hintelmann, Dillon, Evans)

Many scientists consider mercury to be one of the major challenges in the next decade facing environmental research communities and regulators. An increase in atmospheric Hg levels during the past several decades has been measured on a global scale. A significant proportion of mercury in the global cycle is of natural, geogenic origin. This creates considerable challenges for regulators tasked with managing mercury in the environment, and it would be desirable to distinguish natural from anthropogenic mercury sources. The measurement of stable mercury isotope ratios and determination of mercury isotope fractionation can aid to trace mercury from the pollution source to the environment.

New methods have been developed to precisely measure Hg isotope ratios in environmental samples using MC-ICP-MS. The technology has shown significant Hg isotope fractionation during processes such as Hg methylation, reduction and volatilization as well as methylmercury demethylation, leading to considerable variations of Hg isotope ratios in vegetation, sediment and biota such as fish. Comparison of Hg isotope composition in different sources used by industry with Hg isotopes in the environment may allow identification and differentiation between anthropogenic and natural Hg sources.

Dr. Hintelmann was one of a number of principal investigators involved in METAALICUS (Mercury Experiment To Assess Atmospheric Loading In Canada and the US). This whole ecosystem experiment was designed to study the activity, mobility and availability of atmospherically-deposited mercury.  The METAALICUS experiment produced a series of exciting results, and is considered to be one of the premier whole-ecosystem experiments that regulatory agencies and industry followed to assist in implementing reasonable regulations based on sound science.

Identification and Quantification of Organic Contaminants in Aquatic Systems

(Metcalfe, March, Ellis)

Dr. Metcalfe has pioneered work in the analysis of pharmaceuticals and personal care products (PPCPs) in the environment. He and his colleagues have focused on the development of methods that can be applied to the analysis of PPCPs in various environmental matrices, including wastewater, water, soil, sediment and biota. This work has utilized the state-of-the-art liquid chromatography with tandem mass spectrometry (LC-MS/MS) instrumentation in the Water Quality Centre. Dr, Metcalfe has also been using this LC-MS/MS instrumentation to evaluate the transport of pesticides into the aquatic environment and into drinking water after application onto agricultural fields. He has also carried out extensive work on the fate and effects of nanomaterials, including nanosilver. For this work on nanomaterials, the availability of high resolution inductively coupled plasma emission mass spectrometry (ICP-MS) instrumentation in the Water Quality Center has been key to generating data on the distribution of nanoparticles in the aquatic environment.

A major area of his research over the next 3 years will be “non-targeted’ analysis of samples to identify contaminants that we do not currently know are present in the environment. The high resolution mass spectrometers in the Water Quality Centre, will be particularly valuable research tools for elucidating the structure of unknown breakdown products and metabolites that are formed in samples of soil and water.

Dr. D. Ellis, in collaboration with Dr. March, will focus his research on perfluorinated acids in the environment. Perfluorinated acids have been found to be ubiquitous in the environment, being found primarily in the aqueous phase and in biota. They are extremely persistent and bioaccumulative with no known mechanism of degradation. For these reasons, federal government bodies have turned their focus on the large-scale investigation of these pollutants, both in terms of environmental fate and ecotoxicological impacts.

Radionuclides in the Environment

(Evans)

Dr. Evans and his research team are leading the way in developing the field of radiation and nuclear forensics. The work stems from earlier research, done by the team, in environmental measurements of radionuclides. This research requires the development of rapid, ultra-sensitive mass spectrometry methods. Moreover, development of methods to measure rapidly plutonium, for example, at environmental levels requires access to a range of instruments. It has become apparent from their work that there are significant limitations to all advanced mass spectrometers and the best technological solution must be brought to bear if the lowest detection limits are to be achieved. The Water Quality Centre has six different types of ICP-MS available; this is unlike any other centre or facility in Canada. By virtue of their ability to develop methods on multiple platforms, Evans' research team has achieved an understanding of the limitations of each instrument, allowing them to develop methods routinely with detection limits at sub-part-per-quadrillion levels.

Their work on the detection of radionuclides in environmental media has focused on areas that pose potential risk to humans and are amenable to remediation. Thus, for example, Dr. Evans’ team has worked extensively over the last three years on development of on-line methods for the analysis of radium. Radium is a particular problem in drinking water in many areas, as well as a general contaminant released during uranium mining.

Organometalloid Speciation

(Wallschläger, Hintelmann, March, Evans)

Knowledge of total metal content alone does not suffice for risk assessment, as different species exhibit different behaviours and toxicities in the environment. A prime example is the need for speciation information for metalloids such as As and Se, where a number of compounds have been identified in a variety of biological and environmental materials. The different species of As and Se vary greatly with respect to bioavailability, environmental mobility and toxicity. Selenium is a trace element and a micronutrient with ambiguous (eco) toxicological properties. Chronic uptake of Se results in severe impacts on the health of humans and wildlife. At the same time, selenium is of great interest as a nutritional supplement and shows promise as an anticarcinogen.

Dr. Wallschläger and his group have developed methods for As, Se and other metal speciation analysis in both environmental and industrial samples, using IC-DRC-ICP-MS, LC-ES-MS and Q-ToF. In the next years, they will intensify their research on Se biogeochemistry, because new (lower) regulations will make this a key concern. They have begun a project studying Se speciation in ambient waters and the biochemical mechanisms of Se uptake into freshwater algae. As this process can lead to Se biomagnification in aquatic food chains, resulting in ecotoxic effects in water fowl and fish, Dr. Wallschläger and his researchers hope to identify hydrochemical factors and quantify biochemical reaction rates affecting uptake of inorganic Se species from ambient waters and their conversion into organic Se species.

Transport of Sulphur, Carbon and Nitrogen in Catchments and Lakes

(Dillon, Evans, Watmough)

Carbon, nitrogen and sulphur cycling is currently one of the major research topics at the WQC. This is in large part due to climate-mediated redox processes appearing to control the response of ecosystems to changes in acid deposition. Investigations of sulphur dynamics of catchments will be addressed by stable isotope studies. Experiments are planned, where isotopically-enriched sulphur compounds are added to the system as tracers to follow the transport and fate of the sulphur species. Generally, the study is based on the determination of differences in the natural relative abundances of sulphur isotopes and changes therein that occur as the sulphur moves through the catchment and lake. This work requires a large number of sulphur isotope analyses of environmental samples, and is currently done using CF-IRMS.

The study of carbon transport is directed by the interest in the role of dissolved organic carbon (DOC) in aquatic systems, particularly its functions in the transport of trace contaminants, control of metal speciation, toxicity and bioaccumulation rates. Isotope analysis (including N, O and S isotopes in DOC as well as C isotopes) helps elucidate the sources, fate and transport of DOC in catchments and lakes.

As a result of decades of high rates of acid leaching, base cation levels in soils in many regions are approaching levels that may be limiting forest health and productivity. Professors Dillon and Watmough’s combined work on this topic demonstrates that our fundamental understanding of soil acidification is correct and that base cation losses from soils can be quantified. Their findings are extremely important when attempting to scale-up site specific studies to regional or national assessments. This work has enabled the development of steady state critical load models of acidification to be developed.

Biogeochemistry of Trace Metal Contaminants in the Environment Using Stable Isotopes

(Evans, Hintelmann)

Microbes play an important role in the transport of trace metals (e.g. Cu, Zn, Hg, Pb etc.) in the aquatic system. The microbial fractionation of stable isotopes of other heavy metal contaminants than mercury such as Cu, Zn and Pb can also be investigated using mass-spectrometry. Recent laboratory and field studies have demonstrated that organic materials such as metalloproteins and bacteria can generate up to 3 ‰ units of Cu and Fe isotope fractionation. Therefore, stable isotope ratio analysis of heavy metals can be useful in studying sources, pathways and sinks of trace metal contaminants in the aquatic systems.

Development of New Methods for Characterizing DOC and DOC-Metal Interactions

(Guéguen)

The instrumentation operated by the Centre is used in several projects that focus on the development of methods to measure the binding of trace metals to dissolved organic compounds. These studies emphasize mercury, but also include a number of other toxic metals. All of our researchers and their teams bring a diverse range of expertise and different perspectives to the issue, but the opportunity to work collaboratively in the framework of the WQC has been critical to the success of this work.

The Form and Function of Plant Hormones and Structurally Related Compounds

(Emery)

The cytokinin (CK) hormone family can have dramatic effects on plant development and can be used to manipulate processes of vital concern in agriculture such as: seed development and yield, drought tolerance, nitrogen fixation, fruit set and anti-aging effects. Purification and analysis of such a trace level chemical family (comprised of over 45 different compounds) requires extensive purification efforts and expertise in mass spectrometry.  The WQC houses organic mass spectrometers [Quattro and Q-trap LC(ES)MS/MS], which are crucial in the identification and quantification of routinely occurring cytokinins, as well as in the structural elucidation of unknown cytokinins.   The analyses are used to elucidate the role of these hormones in directing the use of assimilates and nutrients among plant organs and the impact of different structural-functional aspects within the cytokinin chemical family.  At both a genomic and metabolite level,Dr. Emery can study how, where and when specific forms of CKs are synthesized and metabolized. To determine functional significance, metabolic and genetic profiling are performed in concert with manipulations at the cellular, whole plant and inter-organism levels. These manipulations often involve mutant or genetically modified plants with strongly altered source-sink phenotypes.