Iodine is a biophilic element with one natural long-lived isotope, 129I (t1/2= 15.6 million years), and one stable isotope, 127I. The inventory of 129I in surface environments has been overwhelmed by anthropogenic releases over the past 50 years. The objective of this study is to utilize the elevated concentration and biophilic nature of 129I and the isotopic ratio of iodine (129I/127I) as a tracer of water mass movement and organic matter. Additionally, the significantly elevated values of 129I/127I could provide a geochronometer, similar to the way 14C is used, particularly for terrestrial organic matter that is less than 50 years old. A series of laboratory experiments and field investigations were carried out to characterize the dominant chemical forms of dissolved iodine, i.e., iodide (I-), iodate (IO 3-), and organic iodine (DOI) in natural waters. Sensitive methods were developed for the analysis of nanomolar quantities of 127I species in a variety of environmental systems using high performance liquid chromatography (HPLC) and an organic iodine decomposition technique, dehydrohalogenation. The potential use of 129I/127I as a hydrological tracer was evaluated through measurements of 129I and 127I, which were carried out in wells in the artificially recharged ground water basin of Orange County, California. Literature values of aquifer ages based on 3H/3He and δ18O tracer data, as well as time-series data of chloride and Santa Ana River flow rates over the past decade were compared to values for 129I and 127I. The iodine isotopes demonstrated a conservative behavior in these aquifers, suggesting that the observed variations of these isotopes reflect past river flow conditions during the time of recharge. The feasibility of using 129I/127I ratios to trace terrestrial organic matter across an estuary was tested. A novel analytical technique to determine 129I/127I ratios in DOI was developed for this investigation. The results of a Galveston Bay transect clearly show that 129I/127I ratios in DOI can remain elevated up to salinity of about 15, but that 129I/127I values of inorganic iodine species do not show any trend with change in salinity gradient due to fast isotopic and chemical equilibration in the estuarine waters.

The most common method of monitoring and mapping groundwatercontaminants is to extract and analyse a number of groundwatersamples from wells in the investigation area. However, thereare a number of limitations with this type of point-wiseinvestigation, as it is hard to acquire an adequate picture ofa heterogeneous and anisotropic subsurface using a fewpoints. To overcome the limitations of point investigations and toimprove ground monitoring investigations in a cost-effectiveway, support can be provided by direct current resistivitymeasurements, which give a characterisation of the electricalproperties of a ground volume. The main objective with this work was to investigate theusability of the resistivity method as a support in monitoringgroundwater contaminants in glaciated terrains and underdifferent seasons, both in long-term monitoring programmes andintracer tests. The work comprised field investigations at several differentsanitary landfills and four tracer tests in differentgeological environments, around the Stockholm region. The maininvestigations have been done at Högbytorp, Stockholmwhich has been used for long-term investigations of theresistivity variation, together with a field set up formonitoring and measurements on seasonal variation in soilmoisture, ground temperature and precipitation. It can be concluded that the use of resistivity measurementssupplies valuable information in the case of mapping andmonitoring conductive groundwater contaminants andfurthermore: The variation in resistivity (in shallow investigations<1 m) can be extensive between different seasons (around30 % compared to a mean value in till and clay soils) andshould be considered, so that anthropogenic affects can beseparated from natural resistivity variation. For deeperinvestigations (>5 m) the seasonal resistivity variationwas more moderate (around 15% compared to a mean value intill and clay soils). Soil moisture variation shows a strong relationship toresistivity variation in the investigated clay and tillsoils. Together with temperature correction 47 to 65% of thevariation has been explained. Three types of monitoring systems can be applied:Permanently installed, partly installed and fully mobilesystems. For the actual measurements, all three types can useeither high-density techniques such as CVES (ContinuousVertical Electrical Sounding) or low-density measuring withone or some different electrode spacings. The suggested evaluation tool for monitoring programmesshowed that it was possible to detect a decrease of 15 % inthe mean value at a specific site using Modified Double Masscalculations between resistivity time series and time seriesat a reference site with a comparable seasonalvariation. Resistivity measurements may be used as a valuablecomplement to groundwater sampling in tracer tests. Adecrease in resistivity, a minimum and a recovery phasereflect the passage of a NaCl-solution, which can be used toestimate flow velocity and flow patterns of the investigatedaquifer. The achieved recovery of NaCl in the tracer testscarried out was estimated to 20 to 70 %. The measurement system for long-term monitoring or tracertests, which should be chosen with regard to layout andfrequency, depends on the purpose of measurement and onsite-specific conditions and therefore no standard solutioncan be proposed. Key words:Resistivity, Direct Current, Monitoring,Groundwater, Contaminant, Tracer test, Geophysics.

Iodine is a biophilic element with one natural long-lived isotope, 129I (t1/2= 15.6 million years), and one stable isotope, 127I. The inventory of 129I in surface environments has been overwhelmed by anthropogenic releases over the past 50 years. The objective of this study is to utilize the elevated concentration and biophilic nature of 129I and the isotopic ratio of iodine (129I/127I) as a tracer of water mass movement and organic matter. Additionally, the significantly elevated values of 129I/127I could provide a geochronometer, similar to the way 14C is used, particularly for terrestrial organic matter that is less than 50 years old. A series of laboratory experiments and field investigations were carried out to characterize the dominant chemical forms of dissolved iodine, i.e., iodide (I-), iodate (IO 3-), and organic iodine (DOI) in natural waters. Sensitive methods were developed for the analysis of nanomolar quantities of 127I species in a variety of environmental systems using high performance liquid chromatography (HPLC) and an organic iodine decomposition technique, dehydrohalogenation. The potential use of 129I/127I as a hydrological tracer was evaluated through measurements of 129I and 127I, which were carried out in wells in the artificially recharged ground water basin of Orange County, California. Literature values of aquifer ages based on 3H/3He and δ18O tracer data, as well as time-series data of chloride and Santa Ana River flow rates over the past decade were compared to values for 129I and 127I. The iodine isotopes demonstrated a conservative behavior in these aquifers, suggesting that the observed variations of these isotopes reflect past river flow conditions during the time of recharge. The feasibility of using 129I/127I ratios to trace terrestrial organic matter across an estuary was tested. A novel analytical technique to determine 129I/127I ratios in DOI was developed for this investigation. The results of a Galveston Bay transect clearly show that 129I/127I ratios in DOI can remain elevated up to salinity of about 15, but that 129I/127I values of inorganic iodine species do not show any trend with change in salinity gradient due to fast isotopic and chemical equilibration in the estuarine waters.

The criteria for diagnosing Alzheimer’s disease (AD) have recently been revised to include the use of biomarkers for the in vivo presence of β-amyloid, one of the neuropathological hallmarks of AD. Examples of such biomarkers are positron emission tomography (PET) β-amyloid specific ligands, including [18F]flutemetamol. The aim of this thesis was to characterize the binding properties of [18F]flutemetamol from a tracer kinetic perspective as well as by validating binding measures through comparison with tissue pathology assessments. The applicability of previously developed kinetic models of tracer binding for voxel-based analysis was examined and compared to arterial input compartment modelling, the “gold standard” for PET quantification. Several voxel-based methods were found to exhibit high correlations with compartment modelling, including the semi-quantitative standardized uptake value ratio (SUVR). The kinetic components of [18F]flutemetamol uptake were also investigated without model assumptions using the data driven method spectral analysis, with binding to β-amyloid shown to relate to a slow kinetic component. The same component was also found to predominate in the uptake of white matter, known to be free of β-amyloid accumulation. White matter uptake was however possible to separate from β-amyloid binding based on the relative contribution of the slow component to the total volume of distribution. Uptake of [18F]flutemetamol as quantified using SUVR or assessed visually was found to correlate well with tissue pathology assessments. Classifying the brains of 68 deceased subjects who had undergone [18F]flutemetamol PET scanning ante mortem, based on the spatial distribution of β-amyloid according to pre-defined phases, revealed that abnormal uptake patterns of [18F]flutemetamol were only certain to be found in the last phase of β-amyloid accumulation. In the same cohort however, [18F]flutemetamol was also shown to accurately distinguish between subjects with AD and non-AD dementia. While this supports the use of [18F]flutemetamol in clinical settings for ruling out AD, the association of abnormal [18F]flutemetamol uptake to late phases of β-amyloid accumulation may limit the detection of early accumulation and pre-clinical stages of AD. It remains to be investigated whether application of voxel-based methods and slow component filtering may increase sensitivity, particularly in the context of clinical trials.

A better understanding of the hydrogeology of mine waste rock and cover systems is essential for the quantification, prediction and reduction of metals loading to the receiving environment. A series of experiments were conducted on an instrumented intermediate-scale waste rock pile at the Cluff Lake Mine in Saskatchewan to investigate the changes in flow and solute transport within coarse waste rock under three different surface conditions. Following these studies, the waste rock pile was deconstructed, structures were mapped, and samples were collected for physical characterization and pore water extraction. The internal structure of the waste rock pile was more important than the texture and topography under the free-dumped and ripped/leveled surface, while the surface condition was found to be the dominant control on spatial and temporal variability of outflow from the waste rock with the covered surface. Data from a deuterium tracer test, lysimeter outflow, and from TDR probes were used to derive estimates of the maximum and an average pore water velocity through the uncovered and the covered waste rock. An average pore water velocity through the matrix materials of the uncovered waste rock was approximately 1.5 m/yr and maximum preferential flow velocities were as high as 5 m/day. The post-cover pressure wave velocity of 0.1 to 1 m/day is inferred from outflow and TDR data, and average pore water velocities (0.39 m/y and 0.73 m/y) are calculated by the water flux and tracer methods, respectively. The distribution of the tracers in pore water and the internal structure were mapped during a detailed deconstruction of the waste rock pile and attempts were made to link the data to the spatial and temporal patterns of lysimeter outflow. The pore water chloride concentrations and the deuterium values did not provide conclusive data necessary to link the spatial and temporal patterns observed in the lysimeter hydrographs to internal structure; however, it provided insight into the internal flow mechanisms and water residence times.

In recent years, wireline temperature profiling methods have evolved to offer new insight into fractured rock hydrogeology. An important advance in temperature logging makes use of boreholes temporarily sealed with flexible impervious fabric liners so that the water column is static and effects of cross-connection are eliminated. For this project a characterization technique was developed based on combining fibre optic distributed temperatures sensing (DTS) with active heating within boreholes sealed with underground liners. DTS systems provide a temperature profiling method that offers improved temporal resolution when compared with wireline trolling based techniques. The ability to collect temperature profiles rapidly in time can improve understanding of transient processes. In this study the advantage of a sealed borehole environment for temperature investigations is demonstrated. Evidence for identifying active groundwater flow under natural gradient conditions using DTS heat pulse testing is presented through a comparison with high resolution geologic logging and hydraulic datasets.

Groundwater is an important water resource that must be protected from potential contamination due to anthropogenic activities such as industrial production and agriculture. It is necessary to understand the presence, movement, and persistence of contaminants in aquifers to develop adequate protection plans. Fractured bedrock aquifers with thin overburden cover are very sensitive to contamination, and little is known about transport processes from the ground surface to depth in this setting. Thus, this research was undertaken to improve the understanding of anthropogenic impacts on water quality in a natural fractured bedrock aquifer with minimal overburden protection. This was accomplished through a field-based investigation conducted in an agricultural setting near Perth, Ontario, Canada. The temporal and spatial variations of several contaminants and indicators (including nitrate, E. coli and polybrominated diphenyl ethers) were examined. A unique infiltration tracer experiment was also conducted to simulate the transport of solutes from the ground surface to wells. Results showed that nitrate concentrations were consistent on a daily scale, but varied monthly. In contrast to nitrate, greater bacterial (E. coli) variability was observed daily. E. coli was not identified in some locations for several months. The temporal variability of concentrations is an important consideration for those consuming groundwater in this setting, as concentrations may be acceptable one month while unsuitable another month (or even another day for fecal bacteria). Annual groundwater monitoring will likely not capture maximum concentrations and thus may not protect human health. Polybrominated diphenyl ethers (flame retardants), which had not been previously measured in groundwater, were detected in the study aquifer at concentrations greater than observed in surface water bodies. It is evident that additional surveys of PBDE concentrations in groundwater are warranted. The infiltration tracer experiment showed that solute transport from the ground surface through thin soil to wells in fractured bedrock can be extremely rapid (on the order of hours) although very complex. This is an important consideration for private and municipally owned drinking water systems that draw water from shallow bedrock aquifers. The results of this research demonstrate that protecting water at the source is imperative in order to preserve water quality in sensitive fractured bedrock aquifers with minimal overburden cover. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2009-10-25 21:37:21.418

Das grundsätzliche Verständnis von Karstgrundwasserleitern ist essentiell für das nachhaltige Management der Rohwasserqualität und letztendlich für sauberes Trinkwasser für bis zu 25 Prozent der Weltbevölkerung. Um dieses Verständnis zu verbessern, wird in der vorliegenden Arbeit das Speicher- und Attenuationspotential eines Karstgrundwasserleiters untersucht. Hierbei werden organische Spurenstoffe als Indikatoren für Transportpfade, Attenuation und Attenuationsprozessen eingesetzt. Als Voraussetzung für die Erfassung belastbarer Daten, wurden geeignete Stabilisierungsstrategien für organische Spurenstoffe in Wasserproben bewertet: Zugabe der Biozide (i) Kupfersulphat und (ii) Natriumazid zu Wasserproben nach der Probenahme und anschließende Lagerung der Proben in flüssiger Form sowie (iii) sofortige Festphasenextraktion (SPE), was zu einer Stabilisierung der Proben durch eine Reduktion des Wassergehaltes führt. Es wurden Fluss- und behandeltes Abwasser untersucht. Diese zeichnen sich üblicherweise durch ein hohes Potential für biologische Aktivität und demnach hohe Biotransformationsraten aus. Analysiert wurde der Einfluss der Lagerungstemperatur von 4 und 28° C für die Proben, die in flüssiger Form gelagert wurden und von 4, 20 und 40° C für die Lagerung der SPE-Kartuschen. Kühlen der Wasserproben allein reichte nicht aus, um die Proben für längere Zeit (> 24 h) zu stabilisieren. Die Zugabe von Kupfersulphat führte zu Problemen mit Azol- und Imidazol-ähnlichen Verbindungen. Natriumazid erwies sich als geeigneter Stabilisierungszusatz. Die besten Ergebnisse konnten für kühl gelagerte SPE-Kartuschen beobachtet werden. Im darauffolgenden Kapitel wird das Langzeitspeicherpotential von Karstgrundwasserleitern untersucht. Um eine nachhaltige Rohwasserqualität zu gewährleisten ist das Verständnis dieses Potentials essentiell. Die Transportdynamik der zwei Herbizide Metazachlor und Atrazin sowie dessen Abbauprodukt (Desethylatrazin) wurde an einer Karstquelle untersucht. Sogar 20 Jahre nach dessen Anwendungsverbot konnten Atrazin und dessen Abbauprodukt nahezu immer im Quellwasser in geringen Konzentrationen (wenige ng L‒1) nachgewiesen werden. Metazachlor dagegen tritt nur nach Niederschlagsereignissen auf und die beobachteten Konzentrationen sind deutlich höher. Ein Vergleich der Dynamik der zwei Herbizide mit der der anorganischen Kationen Ca2+, Mg2+ und der elektrischen Leitfähigkeit zeigte, dass Atrazin mit diesen Parametern korreliert. Aus dieser Beobachtung konnte abgeleitet werden, dass Atrazin innerhalb der Gesteinsmatrix vorliegt und die Rohwasserqualität für Jahrzehnte beeinflusst. Um das in-situ Attenuationspotential innerhalb des Röhrensystems eines Karstgrundwasserleiters zu identifizieren und das Risiko, das von organischen Spurenstoffen ausgeht, abzuschätzen, wurde ein Doppeltracer-Experiment durchgeführt: Der reaktive Stoff Coffein wurde als Markierungsstoff genutzt um das in-situ Attenuationspotential des untersuchten Grundwasserleiters zu bewerten. Aufgrund der niedrigen Bestimmungsgrenze konnten sehr geringe Mengen eingesetzt werden. Um ein Modell zu kalibrieren und die Attenuation des Coffeins zu visualisieren wurde der konservative Markierungsstoff Uranin simultan eingegeben. Diese Methodik wurde in einem gut charakterisierten Karstgrundwasserleiter in Baden-Württemberg getestet. Die Ergebnisse zeigten eine deutlich höhere Attenuationsrate als für einen Karstgrundwasserleiter erwartet wurde. Die Attenuation wurde als Prozess erster Ordnung beschrieben; die bestimmte Halbwertszeit betrug 104 h. Diese geringe Halbwertszeit deutet darauf hin, dass das generell angenommene geringe Attenuationspotential nicht gerechtfertigt ist. Der beobachtete Massenverlust des Coffeins zeigt auf, dass Coffein als reaktiver Markierungsstoff in hydraulisch hochdurchlässigen Systemen, wie Karstgrundwasserleitern, zur Untersuchung des in-situ Attenuationspotentials geeignet ist. Aufgrund der hohen Attenuationsrate des Coffeins, ist nicht mit einer Langzeitkontamination zu rechnen. In der Kombination mit einem konservativen Referenzmarkierungsstoff wird in diesem Kapitel eine ökonomische und ökologisch ungefährliche Methode zur Bestimmung des in-situ Attenuationspotentials vorgestellt. Aufgrund der Ergebnisse des Doppeltracer-Experiments wurde ein Multitracer-Experiment durchgeführt um das ermittelte Attenuationspotential zu verifizieren, dessen Übertragbarkeit auf andere Stoffe zu überprüfen und die Attenuationsprozesse zu spezifizieren. Als Referenzsubstanzen wurden Uranin, Acesulfam und Carbamazepin gemeinsam mit den reaktiven Markierungsstoffen Atenolol, Coffein, Cyclamat, Ibuprofen und Paracetamol in eine Doline eingegeben. Die Durchbruchskurven der reaktiven Markierungsstoffe wurden relativ zu den Referenzsubstanzen ausgewertet. Für keinen der Stoffe konnte eine signifikante Retardation beobachtet werden. Die ermittelten Halbwertszeiten betrugen 38 bis 1400 h (d. h. stabil innerhalb des Beobachtungszeitraums) in der folgenden Reihenfolge (von hoher zu keiner Attenuation absteigend sortiert): Paracetamol > Atenolol ≈ Ibuprofen > Coffein >> Cyclamat. Die Attenuationsraten stimmen generell mit denen aus anderen Studien, die andere Umweltkompartimente untersuchten, und den Ergebnissen des Doppeltracer-Experiments überein. Das Auftreten des Biotransformationsproduktes Atenololsäure diente dem Nachweis von in-situ Biotransformation innerhalb des Karstgrundwasserleitersystems.

A better understanding of the hydrogeology of mine waste rock and cover systems is essential for the quantification, prediction and reduction of metals loading to the receiving environment. A series of experiments were conducted on an instrumented intermediate-scale waste rock pile at the Cluff Lake Mine in Saskatchewan to investigate the changes in flow and solute transport within coarse waste rock under three different surface conditions. Following these studies, the waste rock pile was deconstructed, structures were mapped, and samples were collected for physical characterization and pore water extraction. The internal structure of the waste rock pile was more important than the texture and topography under the free-dumped and ripped/leveled surface, while the surface condition was found to be the dominant control on spatial and temporal variability of outflow from the waste rock with the covered surface. Data from a deuterium tracer test, lysimeter outflow, and from TDR probes were used to derive estimates of the maximum and an average pore water velocity through the uncovered and the covered waste rock. An average pore water velocity through the matrix materials of the uncovered waste rock was approximately 1.5 m/yr and maximum preferential flow velocities were as high as 5 m/day. The post-cover pressure wave velocity of 0.1 to 1 m/day is inferred from outflow and TDR data, and average pore water velocities (0.39 m/y and 0.73 m/y) are calculated by the water flux and tracer methods, respectively. The distribution of the tracers in pore water and the internal structure were mapped during a detailed deconstruction of the waste rock pile and attempts were made to link the data to the spatial and temporal patterns of lysimeter outflow. The pore water chloride concentrations and the deuterium values did not provide conclusive data necessary to link the spatial and temporal patterns observed in the lysimeter hydrographs to internal structure; however, it provided insight into the internal flow mechanisms and water residence times.

Techn. Universiẗat, Diss., 2005--München.