cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.12849002
title: Water isotopes and chemical tools for understanding pesticide transfer in a watershed of the volcanic island of Martinique (French West Indies)

description: Monitoring of water quality over several years has revealed a persistent pesticide contamination of surface and groundwater in several Caribbean Islands, with pesticide concentrations locally over the drinking-water limit set in Europe, i.e. 0.1 µg L<sup>–1</sup> per substance. For Martinique, mainly one pesticide, chlordecone (CLD), remains of major concern despite its withdrawal from the market in 1993. Since the first sampling campaign in 1999–2000, time and space variations of CLD concentrations in surface water and groundwater are still not well understood and difficult to correlate with climate, geological or hydrogeological contexts. We carried out a study in the Chalvet catchment (northeast Martinique) in order to understand more precisely how water movements may explain pesticide transfer. Various tools such as δ<sup>2</sup>H - δ<sup>18</sup>O and chemical parameters were used. Deuterium excess <i>d</i> was proven relevant for determining how CLD is transported in groundwater; it highlighted the role of the groundwater/surface water interaction in spatial and temporal variability of surface water quality. The resulting conceptual hydrogeological model also helps understanding why CLD still has high concentrations in surface water. The approach proposed here can be used in other Caribbean islands that are poorly equipped for explaining pesticide occurrences in surface waters.
DOI: 10.6084/m9.figshare.12849002.v1
title: Water isotopes and chemical tools for understanding pesticide transfer in a watershed of the volcanic island of Martinique (French West Indies)

description: Monitoring of water quality over several years has revealed a persistent pesticide contamination of surface and groundwater in several Caribbean Islands, with pesticide concentrations locally over the drinking-water limit set in Europe, i.e. 0.1 µg L<sup>–1</sup> per substance. For Martinique, mainly one pesticide, chlordecone (CLD), remains of major concern despite its withdrawal from the market in 1993. Since the first sampling campaign in 1999–2000, time and space variations of CLD concentrations in surface water and groundwater are still not well understood and difficult to correlate with climate, geological or hydrogeological contexts. We carried out a study in the Chalvet catchment (northeast Martinique) in order to understand more precisely how water movements may explain pesticide transfer. Various tools such as δ<sup>2</sup>H - δ<sup>18</sup>O and chemical parameters were used. Deuterium excess <i>d</i> was proven relevant for determining how CLD is transported in groundwater; it highlighted the role of the groundwater/surface water interaction in spatial and temporal variability of surface water quality. The resulting conceptual hydrogeological model also helps understanding why CLD still has high concentrations in surface water. The approach proposed here can be used in other Caribbean islands that are poorly equipped for explaining pesticide occurrences in surface waters.
DOI: 10.6084/m9.figshare.13293052
title: The first IAEA inter-laboratory comparison exercise in Latin America and the Caribbean for stable isotope analyses of water samples

description: The use of stable isotopes (<i>δ</i><sup>2</sup>H and <i>δ</i><sup>18</sup>O) is widespread in water resources studies. In the Latin America and the Caribbean (LAC) region, the application of isotope techniques has increased in the past decade, but there remains room to gain self-reliance in environmental isotope studies, necessitating easy and fast access to good-quality isotope data. To that end, in 2018 the IAEA carried out the first regional interlaboratory comparison exercise, testing the analytical performance of 25 laboratories using isotope-ratio mass spectrometry and laser absorption spectroscopy. The three test samples covered a commonly observed range of 0 to –16 ‰ <i>δ</i><sup>18</sup>O and 0 to –115 ‰ <i>δ</i><sup>2</sup>H. z- and ζ-scores were used to benchmark laboratories’ performance against a strict criterion. We found that 81% of the laboratories had satisfactory performance (|z|¯≤ 2) for <i>δ</i><sup>2</sup>H but only 54% achieved similar scores for <i>δ</i><sup>18</sup>O. Only a minor fraction of results (12% for <i>δ</i><sup>2</sup>H and 15% for <i>δ</i><sup>18</sup>O) were unsatisfactory. The larger number of questionable results for <i>δ</i><sup>18</sup>O confirmed the challenges in laser absorption spectroscopy for this isotope. Besides instrumental performance, the sample throughput, laboratory reference materials, and data post-processing were contributing factors to inaccurate or imprecise performance.
DOI: 10.6084/m9.figshare.13293052.v1
title: The first IAEA inter-laboratory comparison exercise in Latin America and the Caribbean for stable isotope analyses of water samples

description: The use of stable isotopes (<i>δ</i><sup>2</sup>H and <i>δ</i><sup>18</sup>O) is widespread in water resources studies. In the Latin America and the Caribbean (LAC) region, the application of isotope techniques has increased in the past decade, but there remains room to gain self-reliance in environmental isotope studies, necessitating easy and fast access to good-quality isotope data. To that end, in 2018 the IAEA carried out the first regional interlaboratory comparison exercise, testing the analytical performance of 25 laboratories using isotope-ratio mass spectrometry and laser absorption spectroscopy. The three test samples covered a commonly observed range of 0 to –16 ‰ <i>δ</i><sup>18</sup>O and 0 to –115 ‰ <i>δ</i><sup>2</sup>H. z- and ζ-scores were used to benchmark laboratories’ performance against a strict criterion. We found that 81% of the laboratories had satisfactory performance (|z|¯≤ 2) for <i>δ</i><sup>2</sup>H but only 54% achieved similar scores for <i>δ</i><sup>18</sup>O. Only a minor fraction of results (12% for <i>δ</i><sup>2</sup>H and 15% for <i>δ</i><sup>18</sup>O) were unsatisfactory. The larger number of questionable results for <i>δ</i><sup>18</sup>O confirmed the challenges in laser absorption spectroscopy for this isotope. Besides instrumental performance, the sample throughput, laboratory reference materials, and data post-processing were contributing factors to inaccurate or imprecise performance.
DOI: 10.6084/m9.figshare.12849008
title: Geochemical evolution, residence times and recharge conditions of the multilayered Tubarão aquifer system (State of São Paulo – Brazil) as indicated by hydrochemical, stable isotope and <sup>14</sup>C data

description: The Tubarão aquifer system constitutes a very complex, multilayered aquifer enclosed in the Paraná basin (central-southern part of Brazil). Despite the relatively low productivity of wells, groundwater represents an important source of water for the very populated and industrialized zones of the State of São Paulo. An extensive water sampling campaign was carried out followed by hydrochemical and isotopic (<i>δ</i><sup>2</sup>H, <i>δ</i><sup>18</sup>O, <i>δ</i><sup>13</sup>C and <sup>14</sup>C) studies, aiming at a better understanding of the aquifer's geochemical evolution, recharge processes, and its groundwater residence times. Two main hydrochemical facies were recognized and divide the aquifer in two portions. The shallow portion – the active hydrological zone of the aquifer – is characterized by the Ca-HCO<sub>3</sub> water type, evolving as a system open to atmospheric CO<sub>2</sub>. Mean residence times are typically lower than 5000 years. The lower portion is mostly characterized by the stagnant, Na-HCO<sub>3</sub> water type, evolving under closed system conditions. Residence times average up to 15,000 years, but can reach 44,000 years, which indicates the exploitation of (possibly non-renewable) fossil waters. This study contributes to the establishment of proper policies regarding the sustainable groundwater exploitation of the Tubarão aquifer system.
DOI: 10.6084/m9.figshare.12849008.v1
title: Geochemical evolution, residence times and recharge conditions of the multilayered Tubarão aquifer system (State of São Paulo – Brazil) as indicated by hydrochemical, stable isotope and <sup>14</sup>C data

description: The Tubarão aquifer system constitutes a very complex, multilayered aquifer enclosed in the Paraná basin (central-southern part of Brazil). Despite the relatively low productivity of wells, groundwater represents an important source of water for the very populated and industrialized zones of the State of São Paulo. An extensive water sampling campaign was carried out followed by hydrochemical and isotopic (<i>δ</i><sup>2</sup>H, <i>δ</i><sup>18</sup>O, <i>δ</i><sup>13</sup>C and <sup>14</sup>C) studies, aiming at a better understanding of the aquifer's geochemical evolution, recharge processes, and its groundwater residence times. Two main hydrochemical facies were recognized and divide the aquifer in two portions. The shallow portion – the active hydrological zone of the aquifer – is characterized by the Ca-HCO<sub>3</sub> water type, evolving as a system open to atmospheric CO<sub>2</sub>. Mean residence times are typically lower than 5000 years. The lower portion is mostly characterized by the stagnant, Na-HCO<sub>3</sub> water type, evolving under closed system conditions. Residence times average up to 15,000 years, but can reach 44,000 years, which indicates the exploitation of (possibly non-renewable) fossil waters. This study contributes to the establishment of proper policies regarding the sustainable groundwater exploitation of the Tubarão aquifer system.
DOI: 10.6084/m9.figshare.12925017
title: Using isotope data to characterize and date groundwater in the southern sector of the Guaraní Aquifer System

description: The Guaraní Aquifer System (SAG) is the largest transboundary aquifer in Latin America, extending beneath parts of Brazil, Paraguay, Argentina, and Uruguay. This paper presents the results of recent hydrogeological studies in the southern portion of the SAG. Locally, the abundance of surface water bodies precluded the use of conventional hydrological tools to characterize groundwater flows. Geological, hydrochemical and environmental isotope investigations were integrated to postulate a revised hydrogeological conceptual model. The revised geological model has provided a better definition of the geometry of the aquifer units and outlined the relevance of regional faults in controlling flow patterns. The new potentiometric map is consistent with groundwater flow from the SAG outcrops to the centre of the Corrientes Province, where upwards flows were identified. Hydrochemical and isotope data confirmed the widespread occurrence of mixing. Noble gas isotopes dissolved in groundwater (<sup>4</sup>He and <sup>81</sup>Kr/Kr) provided residence times ranging from recent recharge up to 770 ± 130 ka. Groundwater age modelling confirmed the role of the geological structures in controlling groundwater flow. The southern sector of the SAG is a multilayer aquifer system with vertical flows and deep regional discharge near the Esteros del Iberá wetland area and along the Paraná and Uruguay rivers.
DOI: 10.6084/m9.figshare.12906871.v1
title: Use of environmental isotopes to assess groundwater pollution caused by agricultural activities

description: This work applied environmental isotope techniques to validate the results of previous studies on recharge sources in a rural area in central Chile (34.3° S and 71.3° W) and discern the origin of nitrate contamination in wells. Stream water and groundwater samples were taken during three surveys, two during spring snowmelt and one in low-water conditions. Chemical analyses included major cations and anions, isotope analyses included <sup>18</sup>O-H<sub>2</sub>O; <sup>2</sup>H-H<sub>2</sub>0; <sup>3</sup>H-H<sub>2</sub>0; <sup>18</sup>O-NO<sub>3</sub><sup>−</sup> and <sup>15</sup>N-NO<sub>3</sub><sup>−</sup>. The stable isotope data show that surface water and deep groundwater present depleted isotope values associated with recharge from the Andes Mountains and that shallow groundwater has more enriched isotope values that reflect the contribution of local recharge from rainwater infiltration. Depleted isotope values observed in shallow groundwater show the effect of recirculated river water used for irrigation. These results are consistent with the conceptual groundwater model developed in previous studies. Some wells have nitrate concentrations above the allowable limit for drinking water. The stable nitrogen isotopes indicate that nitrate is associated mainly with urea and ammoniacal fertilizers, and nitrate is attenuated by denitrification. The results of this study are relevant to improving management of groundwater resources used for drinking water.
DOI: 10.6084/m9.figshare.12957507
title: Identifying groundwater end members by spatio-temporal isotopic and hydrogeochemical records

description: Intensive groundwater use has altered the local hydrological cycle within the Bajío Guanajuatense, Mexico. To improve the knowledge of this hydrogeological system and support water management in the area, groundwater end members were identified using multivariate statistical analysis. Pumped groundwater is composed of two well-mixed end members: (a) recent recharge, affected by a reuse cycle through irrigation where nitrate and chloride evolve and reach levels of 368 mg/L and greater than 100 mg/L, respectively, and (b) deep old groundwater. Mixing estimations show that most wells extract at least 70% of deep groundwater, and some of them extract more than 94%, posing a development and groundwater sustainability conundrum in the area.
DOI: 10.6084/m9.figshare.12906871
title: Use of environmental isotopes to assess groundwater pollution caused by agricultural activities

description: This work applied environmental isotope techniques to validate the results of previous studies on recharge sources in a rural area in central Chile (34.3° S and 71.3° W) and discern the origin of nitrate contamination in wells. Stream water and groundwater samples were taken during three surveys, two during spring snowmelt and one in low-water conditions. Chemical analyses included major cations and anions, isotope analyses included <sup>18</sup>O-H<sub>2</sub>O; <sup>2</sup>H-H<sub>2</sub>0; <sup>3</sup>H-H<sub>2</sub>0; <sup>18</sup>O-NO<sub>3</sub><sup>−</sup> and <sup>15</sup>N-NO<sub>3</sub><sup>−</sup>. The stable isotope data show that surface water and deep groundwater present depleted isotope values associated with recharge from the Andes Mountains and that shallow groundwater has more enriched isotope values that reflect the contribution of local recharge from rainwater infiltration. Depleted isotope values observed in shallow groundwater show the effect of recirculated river water used for irrigation. These results are consistent with the conceptual groundwater model developed in previous studies. Some wells have nitrate concentrations above the allowable limit for drinking water. The stable nitrogen isotopes indicate that nitrate is associated mainly with urea and ammoniacal fertilizers, and nitrate is attenuated by denitrification. The results of this study are relevant to improving management of groundwater resources used for drinking water.
DOI: 10.6084/m9.figshare.12925017.v1
title: Using isotope data to characterize and date groundwater in the southern sector of the Guaraní Aquifer System

description: The Guaraní Aquifer System (SAG) is the largest transboundary aquifer in Latin America, extending beneath parts of Brazil, Paraguay, Argentina, and Uruguay. This paper presents the results of recent hydrogeological studies in the southern portion of the SAG. Locally, the abundance of surface water bodies precluded the use of conventional hydrological tools to characterize groundwater flows. Geological, hydrochemical and environmental isotope investigations were integrated to postulate a revised hydrogeological conceptual model. The revised geological model has provided a better definition of the geometry of the aquifer units and outlined the relevance of regional faults in controlling flow patterns. The new potentiometric map is consistent with groundwater flow from the SAG outcrops to the centre of the Corrientes Province, where upwards flows were identified. Hydrochemical and isotope data confirmed the widespread occurrence of mixing. Noble gas isotopes dissolved in groundwater (<sup>4</sup>He and <sup>81</sup>Kr/Kr) provided residence times ranging from recent recharge up to 770 ± 130 ka. Groundwater age modelling confirmed the role of the geological structures in controlling groundwater flow. The southern sector of the SAG is a multilayer aquifer system with vertical flows and deep regional discharge near the Esteros del Iberá wetland area and along the Paraná and Uruguay rivers.
DOI: 10.6084/m9.figshare.12957507.v1
title: Identifying groundwater end members by spatio-temporal isotopic and hydrogeochemical records

description: Intensive groundwater use has altered the local hydrological cycle within the Bajío Guanajuatense, Mexico. To improve the knowledge of this hydrogeological system and support water management in the area, groundwater end members were identified using multivariate statistical analysis. Pumped groundwater is composed of two well-mixed end members: (a) recent recharge, affected by a reuse cycle through irrigation where nitrate and chloride evolve and reach levels of 368 mg/L and greater than 100 mg/L, respectively, and (b) deep old groundwater. Mixing estimations show that most wells extract at least 70% of deep groundwater, and some of them extract more than 94%, posing a development and groundwater sustainability conundrum in the area.
DOI: 10.6084/m9.figshare.13293055
title: From mountains to cities: a novel isotope hydrological assessment of a tropical water distribution system

description: Water use by anthropogenic activities in the face of climate change invokes a better understanding of headwater sources and lowland urban water allocations. Here, we constrained a Bayesian mixing model with stable isotope data (2018–2019) in rainfall (<i>N</i> = 704), spring water (<i>N</i> = 96), and surface water (<i>N</i> = 94) with seasonal isotope sampling (wet and dry seasons) of an urban aqueduct (<i>N</i> = 215) in the Central Valley of Costa Rica. Low <i>δ</i><sup>18</sup>O rainfall compositions corresponded to the western boundary of the study area, whereas high values were reported to the northeastern limit, reflecting the influence of moisture transport from the Caribbean domain coupled with strong orographic effects over the Pacific slope. The latter is well-depicted in the relative rainfall contributions (west versus east) in two headwater systems: (a) spring (68.7 ± 3.4 %, west domain) and (b) stream (55.8 ± 3.9 %, east domain). The aqueduct exhibited a spatial predominance of spring water and surface water during a normal wet season (78.7 %), whereas deep groundwater and spring water were fundamental sources for the aqueduct in the dry season (69.4 %). Our tracer-based methodology can help improve aqueduct management practices in changing climate, including optimal water allocation and reduced evaporative losses in the dry season.
DOI: 10.6084/m9.figshare.13293055.v1
title: From mountains to cities: a novel isotope hydrological assessment of a tropical water distribution system

description: Water use by anthropogenic activities in the face of climate change invokes a better understanding of headwater sources and lowland urban water allocations. Here, we constrained a Bayesian mixing model with stable isotope data (2018–2019) in rainfall (<i>N</i> = 704), spring water (<i>N</i> = 96), and surface water (<i>N</i> = 94) with seasonal isotope sampling (wet and dry seasons) of an urban aqueduct (<i>N</i> = 215) in the Central Valley of Costa Rica. Low <i>δ</i><sup>18</sup>O rainfall compositions corresponded to the western boundary of the study area, whereas high values were reported to the northeastern limit, reflecting the influence of moisture transport from the Caribbean domain coupled with strong orographic effects over the Pacific slope. The latter is well-depicted in the relative rainfall contributions (west versus east) in two headwater systems: (a) spring (68.7 ± 3.4 %, west domain) and (b) stream (55.8 ± 3.9 %, east domain). The aqueduct exhibited a spatial predominance of spring water and surface water during a normal wet season (78.7 %), whereas deep groundwater and spring water were fundamental sources for the aqueduct in the dry season (69.4 %). Our tracer-based methodology can help improve aqueduct management practices in changing climate, including optimal water allocation and reduced evaporative losses in the dry season.
DOI: 10.6084/m9.figshare.12849005
title: Application of isotope techniques to enhance the conceptual hydrogeological model and to assess groundwater sustainability in the Pampean plain in Córdoba, Argentina

description: The objective of this work is to enhance the conceptual hydrogeological model in the Río Cuarto River basin by using isotope and hydrochemical techniques. The precipitation pattern, as reflected in the average values of <i>δ</i><sup>2</sup>H and <i>δ</i><sup>18</sup>O in stations located in the plains and in the mountains, showed an isotope depletion from the East to the West, attributed to continental and altitude effects. Groundwater quality is mainly the result of two controlling factors: lithology and flow distances from recharge. The aquifers show fresh calcium/sodium bicarbonate water in the upper and medium basin (coarse fluvial sediments) which evolve to sodium sulphate and chloride waters in the low basin (mainly loess and fine alluvial sediments). The confined aquifer systems in the lower basin (C and D systems) averaged more negative stable isotope values, indicating that groundwater recharged during colder climatic conditions (Pleistocene period). Groundwater dating with <sup>14</sup>C confirmed that groundwater ages range from modern to 45,000 years BP showing that as the water flows towards deeper layers and farther from the mountainous recharge area, groundwater age increases. The confined aquifers can potentially be exploited in order to partly cover different water needs but they should be managed in a sustainable way.
DOI: 10.15468/dl.qv28by
title: Occurrence Download

description: A dataset containing 20285 species occurrences available in GBIF matching the query:
{
 "TaxonKey" : [
 "is Opuntia ficus-indica (L.) Mill."
 ]
}

 The dataset includes 20285 records from 402 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0106986-240626123714530/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.5519/qd.atpnme60
title: Query on the Natural History Museum Data Portal (data.nhm.ac.uk) (1 records)