Multi Tracer Research Articles

The effective field theory of large-scale structure and multi-tracer II: redshift space and realistic tracers

We extend the multi-tracer (MT) formalism of the effective field theory of large-scale structure to redshift space, comparing the results of MT to a single-tracer analysis when extracting cosmological parameters from simulations. We used a sub-halo abundance matching method to obtain more realistic multi-tracer galaxy catalogs constructed from N-body simulations. Considering different values for the sample shot noise and volume, we show that the MT error bars on A s, ω cdm, and h in a full-shape analysis are approximately 50% smaller relative to ST. We find that cosmological and bias coefficients from MT are less degenerate, indicating that the MT parameter basis is more orthogonal. We conclude that using MT combined with perturbation theory is a robust and competitive way to accommodate the information present in the mildly non-linear scales.

Groundwater recharge and dating in crystalline basement aquifers of Vea catchment: An integrated environmental tracers’ approach

The crystalline basement aquifers host significant groundwater resources for the communities in Vea catchment for public and irrigational water supply. As part of measures to understand the hydrogeological processes of the area, multi-tracers (SF6, CFC-12, CFC-11, 3H, δ18O and δ2H) were employed to elucidate the groundwater residence time, recharge mechanism and mixing process of the shallow groundwater. Ambient concentrations of these tracers were taken from 10 sampling locations in the Vea catchment of Upper East Region of Ghana. A purge and trap method was used to take the samples and electron capture detector gas chromatography (GC-ECD) was used to analytically measure the SF6 and CFCs gases in the groundwater. The SF6, CFC-11 and CFC-12 dating complimented with 3H revealed that the groundwater age in the catchment was relatively young ranging from 5 to 42 years with a mean age of 23 years. This corroborates well with the stable isotopes data , which showed that the catchment receives modern recharge from meteoric origin. The results also indicated that the estimated SF6 ages were younger compared to the CFCs ages, suggesting additional inputs of SF6 from terrigenous sources. Similarly, a comparison of 3H and CFCs showed little variations in ages in some wells, a possible indication of CFCs degradation. The conceptual groundwater flow model developed showed three groundwater flow regimes along the topographical line. Despite some uncertainties in age interpretations, the multi-environmental tracers have been successfully used to date shallow groundwater in the Vea catchment. To reduce the uncertainties in the age determination, the use multi tracer approach is highly recommended.

The origin and transfer of water and solutes in peatlands: A multi tracer assessment in the carbonated Jura Mountains

AbstractPeatlands provide a large panel of socio‐ecosystemic services such as biodiversity, water and carbon storage and amenities. Hydrological and geochemical interactions between peats and their surroundings are expected to be favoured in mountainous areas, which are nowadays increasingly sensitive to climate changes. In order to provide an integrated scheme of potential interactions, this study evaluates spatio‐temporal patterns of environmental tracers (87Sr/86Sr, δ18O/δ2H, elemental ratios) during high‐ and low‐flow periods in the largest peatland complex of the Jura Mountains (France). Systematically depleted δ18O/δ2H values in the deepest peat pore waters suggest contrasted dynamics and origins, both compatible with either preferential winter recharge or supply from adjacent high‐elevation areas. Combined with strontium isotopes (87Sr/86Sr), we show that these water fluxes are purveyors of solutes derived from water‐rock interactions, modified by mixing, evapotranspiration and dilution with local meteoric inputs. An end member mixing analysis of the peat pore water solute composition is consistent with a major contribution of carbonates from the regional Cretaceous limestone formations, located beneath fluvio‐glacial Quaternary deposits underlying the peat. This contribution implies a significant upward water flux from the underlying syncline that could reach a sufficient hydraulic head thanks to recharge from an adjacent regional anticline. These multiscale (anticline‐syncline, syncline‐peatland, peatland‐surface) constraints allow us to propose a relevant scheme for the hydrogeochemical functioning of the peatland, enabling an improved understanding of the current high socio‐ecosystemic value of the area, and the potential future evolution of the related services.

Using isotopes (strontium and radon) and microbial communities to quantify groundwater mixing influenced by anthropogenic factors at riverside area

Investigating mixing processes between groundwater and surface water is important to manage groundwater system. Especially, because the study site is located around a groundwater heat pump (GWHP) system at a riverside area, external effects such as an operation of GWHP system and/or river level fluctuations can disturb the water system. It can result in artificial mixing of two water bodies, thereby changing original hydrogeochemical and biological characteristics. For this research, a multi–tracer approach combining strontium isotopes, 222Rn, microbial communities, and hydrochemical composition was undertaken for nineteen water samples to quantify how and to what extent mixing may occur due to external processes. Before this approach was applied, the physical experiment using flowmeter was also conducted for defining the effects of dam discharge rates to the flow system. Estimated mixing ratios based on radon tracer showed spatio–temporal variations, influenced by the dam discharge rate, seasonal effects, and GWHP. The average mixing ratio values by strontium tracer were in accordance with the results of radon tracer, suggesting that a dual-tracer approach would be a more reliable means. Mass–transfer calculation indicated that spatio–temporal variations in strontium isotopes were affected by hydrological events. Results from the microbial community using a heat map and principal coordinate analyses also supported the mixing process characteristics of the study area. Based on the results, the interactive and dynamic mixing occurred in the riverside area in relation to external factors causing hydraulic disturbances, and the mixing could be estimated from the combined application of isotopic tracers with microbial community.

Hydrochemical and isotopic characterization of groundwater in the Ghis-Nekor plain (northern Morocco)

The coastal aquifer of Ghis-Nekor (Morocco) was studied to identify the major processes causing salinization of groundwater. In fact, a geochemical approach multi tracer (general chemistry and isotopes - δ2H, δ18O-H2O, δ34S, δ18O-SO4) was utilized, with the hydrodynamics to explain the processes responsible for the salinization of groundwater, and for identttifying areas most vulnerable to seawater intrusion. The recharge of the aquifer is mainly by the Al-Khattabi dam, the Nekor River and the Ghis River, on the eastern border of the plain. The water that feeds the aquifer shows a relatively high level of salinity and for this reason, the majority of sampled wells indicate high values of electric conductivity and total salinity which arrives at 7.5 g L−1. The plot of the geochemical results analyzes of groundwater in the Piper diagram shows two distinct chemical facies; sodium chloride-facies and chlorinated calcium and magnesium sulfated facies. The concentrations of 18O range between −4.15‰ and −5.73‰, while the values of 2H range between −28.4‰ and −41.7‰. The Nekor river water is depleted in heavy isotopes, and the isotopic compositions are in the order on −6‰ for 18O and −40.5‰ for deuterium. Most of the wells have a slope <8 indicating a slight evaporation before infiltration. The data show low and variable d-excess values (range from −0.02‰ to 11.6‰), reflect recharge during different climatic conditions. The isotopic concentrations of 18O-SO4 vary between 4.35‰ and 8.60‰, while the 34S isotope values range from −4.3‰ to 9.9‰. For Ghis River, these values are between −4.4‰ and 4.95‰, respectively, for sulfur and oxygen. The interpretation of the chemical and isotopic results suggesting the intrusion of seawater to increase salinity of groundwater in the region is low. However, only the NE area shows probable contamination of seawater. In contrast, wells are saline independent of seawater intrusion, the origin of the high salinity can be related to: 1- the accumulation of rivers fluid intake and water dam rich dissolved salts and sulphates, 2- the anthropogenic pollution (domestic sewage, agricultural inputs, septic uses).

What can a multi tracer approach tell us about the ecology of two sympatric species of Globicephala genus?

What can a multi tracer approach tell us about the ecology of two sympatric species of Globicephala genus?

A combined remote sensing and multi-tracer approach for localising and assessing groundwater-lake interactions

The combination of thermal imagery and geochemical tracing has been demonstrated as an affordable and effective technique to identify potential groundwater discharge sites in coastal areas on a regional scale. In this paper, a combined multi-tracer approach is evaluated in its applicability to lakes and verified as an appropriate and powerful means to localise and assess groundwater-lake interactions, demonstrated through a case study of Lough Mask in the west of Ireland.Surface water temperature patterns generated from Landsat 7 Thermal Infrared (TIR) images were used to locate groundwater inputs captured as anomalous cold plumes visibly emanating from shallow lake margins during summer months. Radon-222 was used to confirm the presence of groundwater and to detect localised seepage points or groundwater “hotspots”. Conductivity was used as a secondary tracer in support of radon to identify areas of active groundwater inflow.Radon results show that groundwater enters the lake through carboniferous limestones adjacent to the north and east of the lake and no groundwater inflows were observed from the west characterised by Ordivician sandstones and mixed volcanics. The observed strong anti-correlation between mapped radon and satellite derived temperature values implies that decreases in surface water temperatures are associated with increases in radon activity and hence groundwater inputs to the lake. Moreover the spatial pattern of mapped temperature anomaly displays a positive correlation to the mapped radon and conductivity anomalies which further suggests that the tracers are inextricably linked and support a common groundwater source.The study demonstrates the suitability of a multi tracer approach as a comprehensive and cost-effective preliminary screening tool for groundwater-lake interactions with the potential for application elsewhere. This information is important and can be used in support of national water policy and legislation by helping to identify for example, lakes at risk of failure to comply with Water Framework Directive (2000/60/EC) water quality objectives particularly where mapped inputs are linked to groundwater bodies classified as less than good status as per the requirements of the Groundwater Directive (2006/118/EC). Evaluating the potential occurrence and understanding where groundwater discharge occurs is the first step towards more in-depth geochemical surveys that seek to clarify the role played by groundwater in lacustrine biogeochemical budgets.

A multi tracer analysis of thermosphere to stratosphere descent triggered by the 2013 Stratospheric Sudden Warming

AbstractArctic winter observations in 2013 by the Solar Occultation for Ice Experiment (SOFIE) show significant transport from the lower‐thermosphere to the stratosphere of air enriched in nitric oxide, but depleted in water and methane. The transport is triggered by the Stratospheric Sudden Warming (SSW) on 11 January and is continuously tracked for over 3 months. Ultimately, evidence for lower thermospheric air is seen at 40 km in mid‐April. Area integrated nitric oxide (NO) fluxes are compared with previous events in 2004, 2006, and 2009, to show that this event is the second largest in the past 10 years. The SOFIE data are combined with a meteorological analysis to infer descent rates from 40 to 90 km. The descent profile initially peaks near 75 km, shifting downward by approximately 5 km per 10 days. Our work demonstrates the utility of SOFIE tracer measurements in diagnosing vertical transport from the stratosphere to the edge of space.

A multi-tracer study of groundwater origin and transit-time in the aquifers of the Venice region (Italy)

Located in the northeastern region of Italy, the Venetian Plain (VP) is a sedimentary basin containing an extensively exploited groundwater system. The northern part is characterised by a large undifferentiated phreatic aquifer constituted by coarse grain alluvial deposits and recharged by local rainfalls and discharges from the rivers Brenta and Piave. The southern plain is characterised by a series of aquitards and sandy aquifers forming a well-defined artesian multi-aquifer system. In order to determine origins, transit times and mixing proportions of different components in groundwater (GW), a multi tracer study (3H, 3He/4He, 14C, CFC, SF6, 85Kr, 39Ar, 87Sr/86Sr, 18O, 2H, cations, and anions) has been carried out in VP between the rivers Brenta and Piave. The geochemical pattern of GW allows a distinction of the different water origins in the system, in particular based on HCO3-,SO42-,Ca/Mg,NO3-, 18O, 2H. A radiogenic 87Sr signature clearly marks GW originated from the Brenta and Tertiary catchments. End-member analysis and geochemical modelling highlight the existence of a mixing process involving waters recharged from the Brenta and Piave rivers, from the phreatic aquifer and from another GW reservoirs characterised by very low mineralization.Noble gas excesses in respect to atmospheric equilibrium occur in all samples, particularly in the deeper aquifers of the Piave river, but also in phreatic water of the undifferentiated aquifers. 3He–3H ages in the phreatic aquifer and in the shallower level of the multi-aquifer system indicate recharge times in the years 1970–2008. The progression of 3H–3He ages with the distance from the recharge areas together with initial tritium concentration (3H+3Hetrit) imply an infiltration rate of about 1km/y and the absence of older components in these GW. SF6 and 85Kr data corroborate these conclusions. 3H−3He ages in the deeper artesian aquifers suggest a dilution process with older, tritium free waters. 14C Fontes–Garnier model ages of the old GW components range from 1 to 12ka, yielding an apparent GW velocity of about 1–10m/y. Increase of radiogenic 4He follows the progression of 14C ages. 39Ar, radiogenic 4He and 14C tracers yield model-dependent age-ranges in overall good agreement once diffusion of 14C from aquitards, GW dispersion, lithogenic 39Ar production, and 4He production-rate heterogeneities are taken into account. The rate of radiogenic 4He increase with time, deduced by comparison with 14C model ages, is however very low compared to other studies. Comparison with 14C and 13C data obtained 40years ago on the same aquifer system shows that exploitation of GW caused a significant loss of the old groundwater reservoir during this time.

Processes affecting groundwater quality in arid zones: The case of the Bou-Areg coastal aquifer (North Morocco)

The coastal aquifer of Bou-Areg (Morocco) has been studied to identify the main processes causing groundwater salinization, using a multi tracer (general chemistry and isotopes – δ2H, δ18O, δ13C, δ15NNO3, δ18ONO3) geochemical approach. Groundwater is characterized by the widespread occurrence of brackish waters (TDS<500mgL−1) with high cation contents, which are balanced by elevated dissolved NO3- (reaching a maximum of 208mgL−1) and Cl−. Lagoon samples represent a mixture of fresh water and sea water, showing a Na/Cl ratio in agreement with that of sea water and an excess of Ca. The high Ca values represent the main peculiarity of the groundwater–lagoon water system. Two types of groundwater could be identified: (i) freshwater, separated from the whole system and located at the limit of the irrigated area, characterized by low TDS, depleted isotopic composition and relatively high quality; and (ii) water mainly recharged by mountain runoff, interacting with local recharge and acquiring salinity from different sources, thus creating a complex system of dilute waters. Hydrochemical results confirm that the high salinity of the aquifer is caused by the coexistence of dissolution of evaporate rocks and carbonates from Miocene strata, water–rock interaction, and human impacts due to agricultural return flows. The latter represents the main contribution to groundwater salinization, especially in the central part of the aquifer, as well as one of the main causes of the general increase in NO3- concentrations. Only locally, in the southern part of the aquifer, close to the city of Kariat Arkmane, the high salinization observed may be attributed to the presence of lagoon water intrusion. The isotopic composition of dissolved NO3- indicates manure and septic effluents, especially in urban areas and in the central part of the plain, and synthetic fertilizers in the agricultural zone as the main drivers for human induced pollution. The study shows that agricultural return flow has significantly modified the chemistry of the system and it is a prime example of the human-induced changes over coastal environments. Saline water intrusion from the lagoon in the shallow aquifer is negligible, while discharge of polluted groundwater into the lagoon has been found to partially alter its quality.

Biliary excretion of essential trace elements in rats under oxidative stress caused by selenium deficiency

The excretion of essential trace elements, namely, Se, Sr, As, Mn, Co, V, Fe, and Zn into the bile of Se-deficient (SeD) Wistar male rats was studied using the multitracer (MT) technique, and instrumental neutron activation analysis (INAA). Normal and Se-control (SeC) rat groups were used as reference groups to compare the effects of Se levels on the behaviors of the essential trace elements. The excretion (% dose) of Se, Sr, As, Mn, Co, and V increased with Se levels in the liver. The biliary excretion of Mn and As dramatically enhanced for SeC rats compared with SeD rats, while that of V accelerated a little for SeC rats. The radioactivity levels of (59)Fe and (65)Zn in the MT tracer solution were insufficient to measure their excretion into bile. The role of glutathione and bilirubin for biliary excretion of the metals was discussed in relation to Se levels in rat liver.

Investigating astrocytosis with 11C-deuterium-L-Deprenyl in mild cognitive impairment and mild Alzheimer's disease: A multi tracer PET paradigm combining 11C-PIB and 18F-FDG

Investigating astrocytosis with 11C-deuterium-L-Deprenyl in mild cognitive impairment and mild Alzheimer's disease: A multi tracer PET paradigm combining 11C-PIB and 18F-FDG

Multi tracer test for the implementation of enhanced in-situ bioremediation at a BTEX-contaminated megasite

At the Centre for Environmental Research Leipzig-Halle (UFZ) research site in Zeitz, Germany, benzene contaminates the lower of two aquifers with concentrations of up to 20 mg/l. Since the benzene plume has a minimum length of approximately 1 km, enhanced natural attenuation measures are being considered as a remediation strategy. This study describes the performance and evaluation of a multi-species reactive tracer test using the tracers fluorescein and bromide as conservative tracers and toluene as reactive tracer. Sampling was performed over a period of six months using a detailed network of multilevel sampling wells. Toluene was only slightly retarded in comparison to bromide, whereas fluorescein was retarded considerably stronger. Therefore, it was not possible to use fluorescein as an in situ tracer for the determination of groundwater velocities. The ionic nature of fluorescein is assumed to be the major reason for its retardation. The results show that the infiltration conditions were suitable to produce a wide spreading of the tracer front along the full thickness of the aquifer. Thus, a large aquifer volume can be treated in future enhanced bioremediation measures. The total quantity of infiltrated toluene (24 l) was degraded under sulfate-reducing conditions over a flow path of 50 m. Benzylsuccinate was identified as a metabolite of toluene degradation under sulfate-reducing conditions at this site. The modelling results show that toluene degradation was described more accurately using Monod kinetics than first-order kinetics. Since toluene was only slightly retarded in comparison to bromide, sorption and desorption processes were considered to be negligible.

Value of F-18 fluorodeoxyglucose positron emission tomography in thyroid carcinoma

In the preoperative assessment of thyroid nodules, ultrasonography and ultrasonography-guided fine needle aspiration biopsy play the most important role, especially for papillary thyroid cancer. The problem to differentiate follicular adenoma from highly differentiated follicular carcinoma remains the problem in preoperative diagnostic. Also the additional use of a multi tracer imaging strategy (Tl-201/Tc-99 m subtraction scan, Tc-99 m Sestamibi, Tc-99 m Tetrofosmin dual phase scintigraphy) has not solved this problem. Although it is unlikely, the question whether F-18-fluorodeoxy-glucose-positron emission tomography is able to give a better differentiation between benign and malignant tumors in the preoperative assessment of thyroid nodules is not answered up to now. In contrast to preoperative diagnostics F-18-fluorodeoxyglucose-positron emission tomography is of great value in the postoperative follow up of differentiated thyroid cancer. In case of elevated serum thyroglobulin but negative I-131 WBS F-18-fluorodeoxy-glucose-positron emission tomography is the method of choice to detect I-131 negative recurrences and metastases. F-18-fluorodeoxy-glucose uptake in metastases from differentiated thyroid cancer is correlated to low differentiation and maybe bad prognosis. There is also evidence that F-18-fluorodeoxyglucose-positron emission tomography may have a role of in anaplastic and especially in medullary thyroid cancer in the future.

The role of F-18FDG PET in thyroid cancer

Hypofunctioning nodules on scintiscan using Tc-99m Pertechnetate or I-123 have a higher probability of malignancy compared to eu- or hyperfunctioning nodules. However, in the preoperative assessment of thyroid nodules, ultrasonography and ultrasonography guided fine needle aspiration biopsy play the most important role, especially for papillary thyroid cancer. The problem of differentiating follicular adenoma from highly differentiated follicular carcinoma however remains. Also the additional use of a multi tracer imaging strategy (Tl-201/Tc-99m subtraction scan, Tc-99m Sestamibi, Tc-99m Tetrofosmin dual phase scintigraphy) has not solved this problem. Although it is unlikely, the question whether FDG PET is able to give a better differentiation between benign and malignant tumours in the preoperative assessment of thyroid nodules is not answered up to now. In contrast to preoperative diagnostics, FDG PET is of great value in the postoperative follow up of differentiated thyroid cancer. In case of elevated serum thyroglobulin but negative I-131 WBS FDG PET is the method of choice to detect I-131 negative recurrences and metastases. FDG uptake in metastases from differentiated thyroid cancer is correlated to low differentiation and maybe bad prognosis. There is also evidence that FDG PET may have a role in the follow up of anaplastic and especially in medullary thyroid cancer in the future.