Multi-tracer Method Research Articles

Utilizing a multi-tracer method to investigate sulphate contamination: Novel insights on hydrogeochemical characteristics of groundwater in intricate karst systems

Karst environments, especially in Mediterranean area, are highly vulnerable to natural and anthropogenic contamination. This study presents a comprehensive hydrogeochemical assesment of surface water and groundwater across a 2300 km2 catchment area spanning Southern Dalmatia (Croatia) and Western Herzegovina (Bosnia and Herzegovina).For the first time in the study area, data were collected over six years integrating ion analysis, sulphur isotope (δ34S) composition, and physical-chemical analysis of water from 30 locations. The research identified four hydrogeochemical facies (carbonate, sulphate, mixed carbonate/sulphate and chloride), influenced by seawater intrusion, carbonate dissolution, evaporite presence, and human activities.Elevated sulphate levels, often exceeding 250 mg/L, were a main focus of the study due to their potential risks to drinking water quality. The study developed a conceptual model to explain the distribution of sulphates, underscoring the importance of evaporite diapirism and δ34S analysis in tracing sulphate origins. These findings contribute to an improved understanding of karst systems and offer essential data for groundwater protection and legislative measures in the Mediterranean region.

Euclid preparation

Future data provided by the Euclid mission will allow us to better understand the cosmic history of the Universe. A metric of its performance is the figure-of-merit (FoM) of dark energy, usually estimated with Fisher forecasts. The expected FoM has previously been estimated taking into account the two main probes of Euclid, namely the three-dimensional clustering of the spectroscopic galaxy sample, and the so-called 3×2pt signal from the photometric sample (i.e., the weak lensing signal, the galaxy clustering, and their cross-correlation). So far, these two probes have been treated as independent. In this paper, we introduce a new observable given by the ratio of the (angular) two-point correlation function of galaxies from the two surveys. For identical (normalised) selection functions, this observable is unaffected by sampling noise, and its variance is solely controlled by Poisson noise. We present forecasts for Euclid where this multi-tracer method is applied and is particularly relevant because the two surveys will cover the same area of the sky. This method allows for the exploitation of the combination of the spectroscopic and photometric samples. When the correlation between this new observable and the other probes is not taken into account, a significant gain is obtained in the FoM, as well as in the constraints on other cosmological parameters. The benefit is more pronounced for a commonly investigated modified gravity model, namely the γ parametrisation of the growth factor. However, the correlation between the different probes is found to be significant and hence the actual gain is uncertain. We present various strategies for circumventing this issue and still extract useful information from the new observable.

Cosmic Tidal Reconstruction with Halo Fields

Abstract The gravitational coupling between large-scale perturbations and small-scale perturbations leads to anisotropic distortions of the small-scale matter distribution. The measured local small-scale power spectrum can thus be used to infer the large-scale matter distribution. In this paper, we present a new tidal reconstruction algorithm for reconstructing large-scale modes using the full three-dimensional tidal shear information. We apply it to simulated dark matter halo fields and find the reconstructed large-scale density field correlates well with the original matter density field on large scales, improving upon the previous tidal reconstruction method, which only uses two transverse shear fields. This has profound implications for recovering lost 21 cm radial modes due to foreground subtraction and constraining primordial non-Gaussianity using the multitracer method with future cosmological surveys.

Seasonal changes of soil erosion and its spatial distribution on a long gentle hillslope in the Chinese Mollisol region

Understanding seasonal soil erosion and deposition rates and their spatial distribution along sloping farmlands are necessary for erosion prediction technology and implementing effective soil conservation practices. To date seasonal change of soil erosion and soil redistribution on long gentle hillslopes are not fully quantified due to the variable erosive forces in different seasons. A multi-tracer method using rare earth elements (REE) was employed to discriminate seasonal changes of soil erosion and its spatial distribution on a sloping farmland driven by snowmelt runoff, wind force and rainfall-runoff. A long-slope runoff plot with 5 m wide and 320 m long located in the typical Mollisol region of China was divided into eight segments, each of which was 40 m long and tagged with one of eight REE oxides. The spot method of a partial-area tagging scheme was employed and a grid-based layout was used for REE application. Results showed that annual soil erosion rate was 3251.0 t km−2 for the whole runoff plot, in which snowmelt runoff erosion contributed 537.3 t km−2, wind erosion 363.1 t km−2 and rainfall-runoff erosion 2350.6 t km−2. Surface runoff is the main external erosive force of hillslope soil erosion, accounting for 88.8% of the total annual soil loss. Furthermore, for the eight slope segments of the 320-m long hillslope, the sediment transport ratios of each slope segment caused by snowmelt runoff and rainfall-runoff erosion were more than 23.5% and 34.7%, respectively. The results will enrich the understanding of seasonal soil erosion on long hillslopes.

A brief review on cosmological analysis of galaxy surveys with multiple tracers

Galaxy redshift surveys are one of the key probes in modern cosmology. In the data analysis of galaxy surveys, the precision of the statistical measurement is primarily limited by the cosmic variance on large scales. Fortunately, this limitation can in principle be mitigated by observing multiple types of biased tracers. In this brief review, we present the idea of the multi-tracer method, outline key steps in the data analysis and show several worked examples based on the GAMA, BOSS and eBOSS galaxy surveys. This work is a part of a special issue dedicated to the 20th anniversary of RAA (2001–2020), which is prefaced in Wang & Ip ()

Non-Gaussianity constraints using future radio continuum surveys and the multitracer technique

ABSTRACT Tighter constraints on measurements of primordial non-Gaussianity (PNG) will allow the differentiation of inflationary scenarios. The cosmic microwave background bispectrum – the standard method of measuring the local non-Gaussianity – is limited by cosmic variance. Therefore, it is sensible to investigate measurements of non-Gaussianity using the large-scale structure. This can be done by investigating the effects of non-Gaussianity on the power spectrum on large scales. In this study, we forecast the constraints on the local PNG parameter fNL that can be obtained with future radio surveys. We utilize the multitracer method that reduces the effect of cosmic variance and takes advantage of the multiple radio galaxy populations that are differently biased tracers of the same underlying dark matter distribution. Improvements on previous work include the use of observational bias and halo mass estimates, updated simulations, and realistic photometric redshift expectations, thus producing more realistic forecasts. Combinations of Square Kilometre Array simulations and radio observations were used as well as different redshift ranges and redshift bin sizes. It was found that in the most realistic case the 1σ error on fNL falls within the range 4.07–6.58, rivalling the tightest constraints currently available.

The dependence of halo bias on age, concentration, and spin

Halo bias is the main link between the matter distribution and dark matter halos. In its simplest form, halo bias is determined by halo mass, but there are known additional dependencies on other halo properties which are of consequence for accurate modeling of galaxy clustering. Here we present the most precise measurement of these secondary-bias dependencies on halo age, concentration, and spin, for a wide range of halo masses spanning from 10$^{10.7}$ to 10$^{14.7}$ $h^{-1}$ M$_{\odot}$. At the high-mass end, we find no strong evidence of assembly bias for masses above M$_{vir}$ $\sim10^{14}$ $h^{-1}$ M$_{\odot}$. Secondary bias exists, however, for halo concentration and spin, up to cluster-size halos, in agreement with previous findings. For halo spin, we report, for the first time, two different regimes: above M$_{vir}\sim$10$^{11.5}$ $h^{-1}$ M$_{\odot}$, halos with larger values of spin have larger bias, at fixed mass, with the effect reaching almost a factor 2. This trend reverses below this characteristic mass. In addition to these results, we test, for the first time, the performance of a multi-tracer method for the determination of the relative bias between different subsets of halos. We show that this method increases significantly the signal-to-noise of the secondary-bias measurement as compared to a traditional approach. This analysis serves as the basis for follow-up applications of our multi-tracer method to real data.

Using multiple tracers (F−, B, δ11B, and optical brighteners) to distinguish between municipal drinking water and wastewater inputs to urban streams

Releases of municipal waters, including drinking water and wastewater, can considerably alter urban stream chemistry. However, the relative contributions of drinking water versus wastewater to streams have not been quantified previously and are therefore the focus of this study. We sampled streams along a land use gradient that included watersheds with impervious surface areas (ISA) ranging from 1.6 to 62.6%. Samples were analyzed for F−, total B, δ11B, and optical brighteners to determine municipal water inputs to streams. We observed low F− (75 ± 20 μg/L), B (29 ± 6 μg/L), and optical brightener (3.66 ± 0.76 RFU) levels in rural streams, but their concentrations increased with urbanization (up to 475 μg/L, 227 μg/L, and 22.09 RFU, respectively). The δ11B values for drinking waters (16.52 ± 0.39‰) and wastewaters (untreated = 6.06 ± 0.88‰ and treated = 6.46 ± 0.93‰) were distinct, but there was poor correlation between δ11B and ISA for the streams (R2 = 1 × 10−5; p = 0.99), likely due to variable lithology in the study area. We used inverse and three-component mixing models to quantify municipal water inputs to the streams. In densely urbanized watersheds, drinking water and wastewater can respectively contribute up to 54% and 16% of the total streamflow. In addition to our spatial sampling, we collected weekly samples at a suburban stream to test the effects of discharge and seasonality on municipal water tracer behavior. We found that tracer levels did not change significantly (p ≥ 0.28) with discharge or season, suggesting that municipal water inputs are fairly constant. Understanding the relative proportions of differing municipal water types to streams is crucial in guiding infrastructure improvements to conserve drinking water and reduce harmful wastewater releases. The unique chemical signatures of municipal waters aid in the widespread applicability of our multi-tracer method for identifying water sourcing to urban streams.

Application of Multi-Tracer Methods to Evaluate Nitrate Sources and Transformation in Sabkha Matti (Saudi Arabia)

An unusually high concentration of nitrate (NO3) ranging between 291 and 6790 mg/L (as N) was observed during a review of solute data for brine samples from the inland Sabkha Matti. A multi-tracer approach considering water chemistry, stable nitrate isotopes (δ15N and δ18O), and the radioactive isotope of hydrogen (tritium, 3H) was utilized to evaluate the nitrate sources and transformation in this hydrogeological setting. The results suggested that the source of the high nitrate levels is related to a leakage from a manure/septic system near the proximal eastern edge of the Sabkha. Moreover, the impact of Sabkha’s characteristics on biological denitrifications was evaluated in this study. The results suggest that denitrification was not a major process in Sabkha Matti. Several factors may contribute to the limitation of denitrification on the brine samples including high dissolved oxygen contents, high salinity and chloride.

HUNTING DOWN HORIZON-SCALE EFFECTS WITH MULTI-WAVELENGTH SURVEYS

Next-generation cosmological surveys will probe ever larger volumes of the Universe, including the largest scales, near and beyond the horizon. On these scales, the galaxy power spectrum carries signatures of local primordial non-Gaussianity (PNG) and horizon-scale general relativistic (GR) effects. However, cosmic variance limits the detection of horizon-scale effects. Combining different surveys via the multi-tracer method allows us to reduce the effect down cosmic variance. This method benefits from large bias differences between two tracers of the underlying dark matter distribution, which suggests a multi-wavelength combination of large volume surveys that are planned on a similar timescale. We show that the combination of two contemporaneous surveys, a large neutral hydrogen intensity mapping survey in SKA Phase1 and a Euclid-like photometric survey, will provide unprecedented constraints on PNG as well as detection of the GR effects. We forecast that the error on local PNG will break through the cosmic variance limit on cosmic microwave background surveys and achieve $\sigma(f_{NL})\simeq1.4-0.5$, depending on assumed priors, bias, and sky coverage. GR effects are more robust to changes in the assumed fiducial model, and we forecast that they can be detected with a signal-to-noise of about $14$.

Einstein's legacy in galaxy surveys

Abstract Non-Gaussianity in the primordial fluctuations that seeded structure formation produces a signal in the galaxy power spectrum on very large scales. This signal contains vital information about the primordial Universe, but it is very challenging to extract, because of cosmic variance and large-scale systematics – especially after the Planck experiment has already ruled out a large amplitude for the signal. Whilst cosmic variance and experimental systematics can be alleviated by the multitracer method, we here address another systematic – introduced by not using the correct relativistic analysis of the power spectrum on very large scales. In order to reduce the errors on fNL, we need to include measurements on the largest possible scales. Failure to include the relativistic effects on these scales can introduce significant bias in the best-fit value of fNL from future galaxy surveys.

Tracing Sediment Movement on a Semiarid Watershed using Rare Earth Elements

A multi‐tracer method employing rare earth elements (REE) was used to determine sediment yield and to track sediment movement in a small semiarid watershed. A 0.33‐ha watershed near Tombstone, AZ was divided into five morphological units, each tagged with one of five REE oxides. Relative contribution of each unit to the total sediment yield was determined by collecting runoff and sediment, and the spatial redistribution of sediment was determined from sampling the soil surface. Average sediment yield was 1.0 Mg ha−1 yr−1 from the entire watershed, but varied between 0.1 Mg ha−1 yr−1 from the upper slope to 5.0 Mg ha−1 yr−1 from the lower channel. Little re‐deposition occurred in the channels indicating an effective transport system. The erosion pattern and rates were in agreement with the current morphology of the watershed, which has a well‐developed channel network.

Investigation of adsorption behaviour of fission products in soils using multitracer technique

The adsorption mechanism of fission products in soils has been investigated by using multitracer technique. The multitracer method used in this work contained fission products as carrier free isotopes which were prepared by neutron irradiation of 235U at Kyoto University Research Reactor. After the soil sample was mixed into the multitracer solution for two weeks, the solution was separated from soil sample. The gamma-ray spectrometry was carried out for the separated solution and the original multitracer solution which has not been mixed with soils. Distribution coefficients of fission products for soil samples were estimated by measured photoelectric peaks. In this work, distribution coefficients of ten elements for thirty typical Japanese soils were observed.

Coupling of ICP-MS and Multitracer Technique as a New Method to Investigate Dynamics of Various Elements in Soil-water System

Abstract Coupled application of multitracer method for the sorption experiments and ICP-MS for leaching experiments was proposed as a new method to study the dynamics of various elements in soil–water systems. This method enables us to obtain reversibility and the time required to attain the steady-state simultaneously for various elements in soil–water system. An example of the results obtained by this method was shown for the case of Co in this letter.

Diffusion Measurements in Chromium-Manganese Steels by Means of Multiple Radiotracer Test

The paper presents the application of multitracer method of diffusion measurement in Cr-Mn steels. Two austenitic steels were investigated: Cr13Mn18SiCa and Cr17Mn17 as well as austenitic-ferritic one: Cr15Mn19. The serial sectioning technique was used for simultaneous evaluation of diffusion coefficients of radioisotopes of chromium 51Cr, manganese 54Mn and iron 59Fe at 1073K and 1173 K. Diffusion coefficients of radiotracers at 1173 K were calculated on the basis of both: activity of removed layer (differential method) and residual activity of the sample (integral method). The evaluated diffusion coefficients of metals in austenitic steels are higher than those in austenitic-ferritic one; their values are about 10-12 ÷ 10-11 cm2s-1. Moreover it was found that at 1173 K the diffusion rate of manganese is higher than that for iron and chromium while at 1073 K diffusion rates of chromium and manganese are comparable and higher than that for iron. Furthermore the experimental results point out that at 1173 K the volume diffusion is the dominant mechanism of metals’ transport while at 1073 K the high diffusivity paths diffusion prevails.

Tracking sediment redistribution in a small watershed: implications for agro‐landscape evolution

AbstractA new, multi‐tracer method is used to track erosion, translocation, and redeposition of sediment in a small watershed, thus allowing for the first time a complete, spatially distributed, sediment balance to be made as a function of landscape position. A 0·68 ha watershed near Coshocton, Ohio, USA was divided into six morphological units, each tagged with one of six rare earth element oxides. Sediment translocation was evaluated by collecting run‐off and by spatially sampling the soil surface. Average measured erosion rate was 6·1 t ha−1, but varied between 40·4 t ha−1 loss from the lower channels to 24·1 t ha−1 gain on the toeslope. With this technique it was possible for the first time to itemize the sediment budget for landscape elements into three components: (1) the soil from the element that left the watershed with run‐off; (2) soil from the element that was redeposited on lower positions, with the spatial distribution of that deposition; and (3) soil originating from the upper positions and deposited on the element, with quantification of relative source areas. The results are incongruous with the current morphology of the watershed, suggesting that diffusion‐type erosion must also play a major role in defining the evolution of this landscape. Copyright © 2004 John Wiley & Sons, Ltd.

Tracer tests for the investigation of heterogeneous porous media and stochastic modelling of flow and transport—a review of some recent developments

In heterogeneous porous aquifers, simulations and predictions of groundwater flow and solute (contaminant) transport require detailed knowledge of aquifer parameters and their spatial distribution. In most cases this information cannot easily be obtained at acceptable expenses. In general, subsurface investigation techniques are applied only at borehole locations, and the parameter values measured have to be regionalized in order to obtain continuous parameter fields. Geophysical measurements very often yield unsatisfactory results due to resolution, detection range and parameterisation problems. In such situations tracer tests offer the possibility to efficiently investigate the aquifer between the wells and to characterize the relevant aquifer properties based on effective parameter values. Tracer tests can be performed at laboratory and field-scales with depth integrated (two-dimensional) or multilevel (three-dimensional) set-ups, and under natural or forced hydraulic gradient conditions. Both non-reactive and reactive tracer compounds can be used. This contribution covers and gives examples on the following topics: depth integrated and three-dimensional natural and forced gradient tracer test methods together with their fields of application at different transport scales, novel tracer compounds and applications, high resolution multilevel–multitracer methods and high resolution multilevel–multitracer equipment, as well as approaches to evaluate tracer experiments and to quantify tracer transport. In this way the paper shows some recent trends in tracer based subsurface investigation and emphasizes the advantages and importance of modern tracer testing.

Complexation and extraction studies of lanthanide ions by 1,1′-(3,6,9-Trioxaundecanedionyl)Diphenothiazine

Solid complexes of lanthanide picrates with 1,1′-(3,6,9-trioxaundecanedionyl)diphenothiazine (L), [Ln(pic)3L] (Ln = La, Nd, Eu, Gd, Er, Y), have been prepared and characterized by elemental analysis, IR and 1H NMR spectra. The molecular structure of [Er(pic)3L]·1/2C2H5OH shows that five oxygens of L form a ring-like coordination structure. Er(III) is 9-coordinated by L together with the other two unidentate and one bidentate picrate anions, revealing a tri-capped distorted trigonal prism geometry. Solvent extraction of Ln(III) with L has been carried out in a water–nitrobenzene system by use of the multitracer method. The relationship between the complex structure and extractabilities of the ligand is discussed.

Radioisotope production in target fragmentation with high-energy heavy ions at HIMAC

In order to improve utilisation of the multitracer method, two aspects of the method were pursued in this study. The production of radioisotopes from target fragmentation of 197Au nuclei was performed with high-energetic heavy ions of 12C (180, 290, 400 MeV/u) and 40Ar (290, 650 MeV/u) at HIMAC facilities. The yields of products were measured by using a thick-target-thickcatcher method and off-line γ-ray spectrometry with Ge semiconductor detectors. Besides, a special apparatus for practice of the radioisotope production was designed in application of the tracers for separation of the products from target material with high efficiency and the target material and shape for the design was investigated in a trial examination.

The use of non-conservative parameters to trace wastewater effluents in water bodies

This paper describes an alternative method to label wastewater effluent entering water bodies when “classic” tracers (artificial tracers and conservative parameters of the water masses) cannot be used. The method is based on the simultaneous use of several non-conservative effluent quality parameters (e.g. electrical conductivity, detergents, TDS, PO 4, alkalinity, Na, Kjeldahl, NH 4 and NO 2). The simultaneous use of several parameters enables to smooth out the high variability of single non-conservative parameters disclosing their common trend. The obtained estimates are not quantitative but can be expressed in an ordinal scale. The performance of the new multi-tracer method is tested in a case study to estimate the relative amount of effluent in the outflow of an operational reservoir which receives freshwater and sporadic inputs of treated wastewater. The multi-tracer method disclosed poor mixing conditions between freshwater and effluents within the reservoir, plug flow-like movement of the effluent pulses with a delay of 1–3 weeks between an in-pulse and its corresponding out-pulse, and the existence of dead spaces in the reservoir.