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  1. Article ; Online: Monitor changes to ice-bound nuclear fallout in Antarctica.

    Saunders, Krystyna M / Meredith, Karina T

    Nature

    2023  Volume 619, Issue 7970, Page(s) 465

    MeSH term(s) Antarctic Regions ; Ice Cover/chemistry ; Global Warming ; Radioisotopes/analysis ; Environmental Pollutants/analysis ; Nuclear Weapons
    Chemical Substances Radioisotopes ; Environmental Pollutants
    Language English
    Publishing date 2023-08-07
    Publishing country England
    Document type Letter
    ZDB-ID 120714-3
    ISSN 1476-4687 ; 0028-0836
    ISSN (online) 1476-4687
    ISSN 0028-0836
    DOI 10.1038/d41586-023-02246-9
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  2. Article ; Online: Study of groundwater recharge using combined unsaturated‐and saturated‐zone chloride mass balance methods

    Jiang, Sanyuan / Rao, Wenbo / Han, Liangfeng / Meredith, Karina T.

    Hydrological Processes. 2023 June, v. 37, no. 6 p.e14927-

    2023  

    Abstract: Understanding groundwater recharge mechanisms is essential for reliable groundwater recharge estimation for sustainable groundwater resource assessment and management, especially in arid and semiarid areas. In this study, chloride, together with stable ... ...

    Abstract Understanding groundwater recharge mechanisms is essential for reliable groundwater recharge estimation for sustainable groundwater resource assessment and management, especially in arid and semiarid areas. In this study, chloride, together with stable isotopes (¹⁸O and ²H), in 1‐year rainfall, soil water from representative profiles, and groundwater samples, collected in the Ordos Plateau, northern China were analysed. Groundwater recharge was estimated using unsaturated‐ and saturated‐zone chloride mass balance (CMB). An equation that describes the relationship between chloride concentrations in saturated zone water (Cₛz) and soil water residence time (τ) was derived. With the help of the relationship, chloride concentrations in unsaturated zone water (Cᵤz) and in groundwater (Cₛz) can be used to uncover water flow and chloride transport in the unsaturated zone. The relationship between Cₛz and Cᵤz indicates that, the groundwater was recharged mainly by intense rainfall events. Small rainfall events did not lead to groundwater recharge but contributed to the flux of chloride to soil surface. Stable isotopic compositions of ¹⁸O and ²H provided corroborative evidence of the recharge processes. The relationship between Cₛz and τ indicates further that there is no source of chloride in the groundwater other than that from precipitation. Thus, Cₛz can give more reliable recharge estimates. Cᵤz was influenced by heavy rainfall‐induced runoff, run‐on and bypass flow events and cannot give reliable recharge estimates. However, if used jointly with Cₛz, Cᵤz can help to gain insights into recharge processes and yield groundwater recharge estimates with higher certainty. The outcomes of this study can assist for groundwater recharge investigation and assessment in regions where the assumptions and boundary conditions necessary for the correct application of the CMB method may not be met.
    Keywords chlorides ; equations ; groundwater ; groundwater recharge ; preferential flow ; rain ; runoff ; soil water ; water flow ; China
    Language English
    Dates of publication 2023-06
    Publishing place John Wiley & Sons, Inc.
    Document type Article ; Online
    Note JOURNAL ARTICLE
    ZDB-ID 1479953-4
    ISSN 1099-1085 ; 0885-6087
    ISSN (online) 1099-1085
    ISSN 0885-6087
    DOI 10.1002/hyp.14927
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  3. Article ; Online: Hydrochemical and isotopic baselines for understanding hydrological processes across Macquarie Island.

    Meredith, Karina T / Saunders, Krystyna M / McDonough, Liza K / McGeoch, Melodie

    Scientific reports

    2022  Volume 12, Issue 1, Page(s) 21266

    Abstract: Isotopic and hydrochemical data from lakes provide direct information on catchment response to changing rainfall, evaporation, nutrient cycling, and the health of ecosystems. These techniques have not been widely applied to lakes in the Southern ... ...

    Abstract Isotopic and hydrochemical data from lakes provide direct information on catchment response to changing rainfall, evaporation, nutrient cycling, and the health of ecosystems. These techniques have not been widely applied to lakes in the Southern Hemisphere high latitudes, including Southern Ocean Islands (SOIs) experiencing rapid, significant shifts in climate. Historical work has highlighted the localised nature of geochemical drivers in controlling the hydrochemical evolution of lakes, such as geology, sea spray contribution, vegetation, geographical location, and ice cover extent. The role of groundwater in lake hydrology and hydrochemistry has not been identified until now, and its omission will have major implications for interpreting soil-water-air processes affecting lakes. Here we present the first comprehensive, island-wide hydrochemical and isotopic survey of lakes on a SOI. Forty lakes were examined across Macquarie Island, using comparable methods to identify key environmental processes and their geochemical drivers. Methods include stable carbon (δ
    MeSH term(s) Ecosystem ; Hydrology ; Geology ; Carbon ; Water
    Chemical Substances Carbon (7440-44-0) ; Water (059QF0KO0R)
    Language English
    Publishing date 2022-12-08
    Publishing country England
    Document type Journal Article
    ZDB-ID 2615211-3
    ISSN 2045-2322 ; 2045-2322
    ISSN (online) 2045-2322
    ISSN 2045-2322
    DOI 10.1038/s41598-022-25115-3
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  4. Article: Using isotopes to determine the natural and anthropogenic processes influencing water quality in household wells of Chronic kidney disease of unknown origin (CKDu) endemic Medawachchiya area, Sri Lanka

    Nikagolla, Chandima / Dawes, Les A. / Millar, Graeme J. / Meredith, Karina T. / Banati, Richard B.

    Journal of hydrology. 2021 Sept., v. 600

    2021  

    Abstract: The groundwater in the dry climatic, agricultural regions of Sri Lanka has been a focus of research for more than two decades as a likely contributor to the epidemic chronic kidney disease that does not have an identified causality (CKDu). The intense ... ...

    Abstract The groundwater in the dry climatic, agricultural regions of Sri Lanka has been a focus of research for more than two decades as a likely contributor to the epidemic chronic kidney disease that does not have an identified causality (CKDu). The intense agriculture that heavily depends on irrigation and excessive use of agrochemicals, as well as the increasing population that prompt over-extraction and sewage discharge presents increasing threats to these groundwaters. Particulate organic matter (POM), stable environmental isotopes (¹³C, ¹⁵N, ¹⁸O and ²H) together with hydrochemistry were used to determine the natural and anthropogenic sources of solutes, and their dynamics in these waters. Twenty nine domestic drinking water wells and spring were sampled from CKDu endemic Medawachchiya area during the dry season of 2018. POM of most waters were found to have aquatic origin resulted from biological processes that assimilate nutrients in groundwater. The isotopic compositions (¹⁸O and ¹⁵N) of nitrate provided evidence for anthropogenic nitrate inputs in some wells and denitrification of potentially anthropogenic nitrates in others. These waters were recharged locally and subjected to varying degrees of evaporation. The water–rock interactions, evaporation, and anthropogenic inputs significantly influence shallow drinking water quality in wells (<4 m below ground surface). In contrast, deeper domestic drinking wells (<4 m below ground surface) potentially connect with deep groundwater. This study emphasises the importance of the integrated use of POM, environmental isotopes, and water chemistry in identifying the dynamics of solutes in groundwater, thereby determining the overall groundwater quality, especially in investigating complex environmental health problems like CKDu.
    Keywords agrochemicals ; denitrification ; dry season ; environmental health ; evaporation ; groundwater ; hydrochemistry ; irrigation ; kidney diseases ; nitrates ; particulate organic matter ; sewage ; spring ; water quality ; Sri Lanka
    Language English
    Dates of publication 2021-09
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 1473173-3
    ISSN 1879-2707 ; 0022-1694
    ISSN (online) 1879-2707
    ISSN 0022-1694
    DOI 10.1016/j.jhydrol.2021.126623
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  5. Article: Water uptake of riparian plants in the lower Lhasa River Basin, South Tibetan Plateau using stable water isotopes

    Rao, Wenbo / Chen, Xi / Meredith, Karina T / Tan, Hongbing / Gao, Man / Liu, Jintao

    Hydrological processes. 2020 July 30, v. 34, no. 16

    2020  

    Abstract: Riparian plants can adapt their water uptake strategies based on climatic and hydrological conditions within a river basin. The response of cold‐alpine riparian trees to changes in water availability is poorly understood. The Lhasa River is a ... ...

    Abstract Riparian plants can adapt their water uptake strategies based on climatic and hydrological conditions within a river basin. The response of cold‐alpine riparian trees to changes in water availability is poorly understood. The Lhasa River is a representative cold‐alpine river in South Tibet and an under‐studied environment. Therefore, a 96 km section of the lower Lhasa River was selected for a study on the water‐use patterns of riparian plants. Plant water, soil water, groundwater and river water were measured at three sites for δ¹⁸O and δ²H values during the warm‐wet and cold‐dry periods in 2018. Soil profiles differed in isotope values between seasons and with the distance along the river. During the cold‐dry period, the upper parts of the soil profiles were significantly affected by evaporation. During the warm‐wet period, the soil profile was influenced by precipitation infiltration in the upper reaches of the study area and by various water sources in the lower reaches. Calculations using the IsoSource model indicated that the mature salix and birch trees (Salix cheilophila Schneid. and Betula platyphylla Suk.) accessed water from multiple sources during the cold‐dry period, whereas they sourced more than 70% of their requirement from the upper 60–80 cm of the soil profile during the warm‐wet period. The model indicated that the immature rose willow tree (Tamarix ramosissima Ledeb) accessed 66% of its water from the surface soil during the cold‐dry period, but used the deeper layers during the warm‐wet period. The plant type was not the dominant factor driving water uptake patterns in mature plants. Our findings can contribute to strategies for the sustainable development of cold‐alpine riparian ecosystems. It is recommended that reducing plantation density and collocating plants with different rooting depths would be conducive to optimal plant growth in this environment.
    Keywords Salix ; Tamarix ramosissima ; evaporation ; groundwater ; models ; plant growth ; planting density ; river water ; rivers ; soil profiles ; soil water ; sustainable development ; trees ; water uptake ; watersheds ; China
    Language English
    Dates of publication 2020-0730
    Size p. 3492-3505.
    Publishing place John Wiley & Sons, Inc.
    Document type Article
    Note NAL-AP-2-clean ; JOURNAL ARTICLE
    ZDB-ID 1479953-4
    ISSN 1099-1085 ; 0885-6087
    ISSN (online) 1099-1085
    ISSN 0885-6087
    DOI 10.1002/hyp.13831
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  6. Article: A review of the use of radiocarbon to estimate groundwater residence times in semi-arid and arid areas

    Cartwright, Ian / Currell, Matthew J / Cendón, Dioni I / Meredith, Karina T

    Elsevier B.V. Journal of hydrology. 2020 Jan., v. 580

    2020  

    Abstract: Groundwater is an important resource in arid and semi-arid regions and determining its residence times is critical for sustainable use. Radiocarbon (14C) is currently the primary geochemical tracer for determining residence times of regional groundwater ... ...

    Abstract Groundwater is an important resource in arid and semi-arid regions and determining its residence times is critical for sustainable use. Radiocarbon (14C) is currently the primary geochemical tracer for determining residence times of regional groundwater systems. The analysis of 14C contents of dissolved inorganic carbon (DIC) became more straightforward following the development of accelerator mass spectrometry, which has led to an increase in the number of studies using 14C. However, the interpretation of 14C data is not always straightforward and many studies consider relatively few of the multiple processes that may affect the 14C contents of DIC in groundwater. Commonly, studies have focussed on correcting 14C contents for closed-system dissolution of 14C-free calcite, which is a near-ubiquitous process. However, especially in semi-arid and arid areas, uncertainties in the initial 14C contents and δ13C values of recharge due to the presence of low-14C soil CO2 in the deep unsaturated zone, recharge by rivers, or open-system calcite dissolution pose problems for mass balance calculations. Additionally, processes such as methanogenesis and mineralisation of organic carbon may be locally important. Most studies also assume a constant atmospheric 14C content and non-dispersive piston flow in aquifers, which results in residence times being underestimated and makes it difficult to compare the groundwater archive to other palaeoclimate or palaeoenvironment records. Additionally, mixing of water within aquifers, diffusion of 14C between low and high permeability layers, and sampling from multiple units in long-screen wells may limit whether a meaningful residence time can be determined. Overall, while it is relatively straightforward to estimate broad ranges of residence times or determine general patterns of groundwater flow, the quest to quantify residence times, flow rates, and recharge remains a challenge. The use of multiple radioactive tracers, better characterisation of δ13C values and 14C contents of the potential sources of DIC, and more critical assessment of flow systems will improve the utilisation of this important tracer.
    Keywords aquifers ; calcite ; carbon 14 ; carbon dioxide ; dissolved inorganic carbon ; groundwater ; groundwater flow ; groundwater recharge ; mass spectrometry ; methane production ; mineralization ; mixing ; organic carbon ; paleoclimatology ; paleoecology ; permeability ; radiolabeling ; rivers ; semiarid zones ; soil ; stable isotopes ; uncertainty ; wells
    Language English
    Dates of publication 2020-01
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 1473173-3
    ISSN 1879-2707 ; 0022-1694
    ISSN (online) 1879-2707
    ISSN 0022-1694
    DOI 10.1016/j.jhydrol.2019.124247
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  7. Article ; Online: Emerging biological archives can reveal ecological and climatic change in Antarctica

    Strugnell, Jan M. / McGregor, Helen V. / Wilson, Nerida G. / Meredith, Karina T. / Chown, Steven / Lau, Sally C. Y. / Robinson, Sharon A. / Saunders, Krystyna M.

    Global Change Biology. 2022 Nov., v. 28, no. 22 p.6483-6508

    2022  

    Abstract: Anthropogenic climate change is causing observable changes in Antarctica and the Southern Ocean including increased air and ocean temperatures, glacial melt leading to sea‐level rise and a reduction in salinity, and changes to freshwater water ... ...

    Abstract Anthropogenic climate change is causing observable changes in Antarctica and the Southern Ocean including increased air and ocean temperatures, glacial melt leading to sea‐level rise and a reduction in salinity, and changes to freshwater water availability on land. These changes impact local Antarctic ecosystems and the Earth's climate system. The Antarctic has experienced significant past environmental change, including cycles of glaciation over the Quaternary Period (the past ~2.6 million years). Understanding Antarctica's paleoecosystems, and the corresponding paleoenvironments and climates that have shaped them, provides insight into present day ecosystem change, and importantly, helps constrain model projections of future change. Biological archives such as extant moss beds and peat profiles, biological proxies in lake and marine sediments, vertebrate animal colonies, and extant terrestrial and benthic marine invertebrates, complement other Antarctic paleoclimate archives by recording the nature and rate of past ecological change, the paleoenvironmental drivers of that change, and constrain current ecosystem and climate models. These archives provide invaluable information about terrestrial ice‐free areas, a key location for Antarctic biodiversity, and the continental margin which is important for understanding ice sheet dynamics. Recent significant advances in analytical techniques (e.g., genomics, biogeochemical analyses) have led to new applications and greater power in elucidating the environmental records contained within biological archives. Paleoecological and paleoclimate discoveries derived from biological archives, and integration with existing data from other paleoclimate data sources, will significantly expand our understanding of past, present, and future ecological change, alongside climate change, in a unique, globally significant region.
    Keywords Quaternary period ; air ; biodiversity ; climate ; climate change ; ecosystems ; freshwater ; genomics ; glaciation ; ice ; lakes ; mosses and liverworts ; paleoclimatology ; paleoecology ; peat ; salinity ; sea level ; vertebrates ; Antarctic region ; Antarctica
    Language English
    Dates of publication 2022-11
    Size p. 6483-6508.
    Publishing place John Wiley & Sons, Ltd
    Document type Article ; Online
    Note REVIEW
    ZDB-ID 1281439-8
    ISSN 1365-2486 ; 1354-1013
    ISSN (online) 1365-2486
    ISSN 1354-1013
    DOI 10.1111/gcb.16356
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  8. Article ; Online: Using water quality and isotope studies to inform research in chronic kidney disease of unknown aetiology endemic areas in Sri Lanka.

    Nikagolla, Chandima / Meredith, Karina T / Dawes, Les A / Banati, Richard B / Millar, Graeme J

    The Science of the total environment

    2020  Volume 745, Page(s) 140896

    Abstract: Chronic Kidney Disease of unknown aetiology (CKDu) is a major public health concern in dry climatic, agricultural regions of Sri Lanka. The chemistry of groundwater (the main source of drinking water) in the area has been studied extensively, in relation ...

    Abstract Chronic Kidney Disease of unknown aetiology (CKDu) is a major public health concern in dry climatic, agricultural regions of Sri Lanka. The chemistry of groundwater (the main source of drinking water) in the area has been studied extensively, in relation to the occurrence of CKDu. This paper investigates water quality studies published in CKDu affected areas of Sri Lanka and also presents a new data set of 27 hydrochemical and isotopic samples collected from groundwater wells in selected CKDu endemic areas in Sri Lanka. The study outcomes do not provide evidence of pollutants such as heavy metals in groundwater. However, the study identifies elevated concentrations of silica which requires further investigation. Two groups of groundwater have been identified based on the isotopic results suggesting different sources or origins. The available water quality data, including the data from this study, is not sufficient to answer questions on whether the chemistry of groundwater is related to the CKDu occurrence. However, this study identifies the importance of detailed investigation into degradation products of agrochemicals, the organic matter content and the influence of elevate silica concentration in groundwater. The study also provides research directions in the form of isotopic tracers and the frequency of sampling that is needed to capture potential pollutants in future groundwater quality studies in CKDu endemic areas in Sri Lanka.
    MeSH term(s) Groundwater ; Humans ; Isotopes ; Renal Insufficiency, Chronic/epidemiology ; Sri Lanka/epidemiology ; Water Quality
    Chemical Substances Isotopes
    Language English
    Publishing date 2020-07-16
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 121506-1
    ISSN 1879-1026 ; 0048-9697
    ISSN (online) 1879-1026
    ISSN 0048-9697
    DOI 10.1016/j.scitotenv.2020.140896
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  9. Article ; Online: Corrigendum to "Using water quality and isotope studies to inform research in chronic kidney disease of unknown aetiology endemic areas in Sri Lanka" [Sci. Total Environ., Volume 745(2020)/Article Number 140896].

    Nikagolla, Chandima / Meredith, Karina T / Dawes, Les A / Banati, Richard B / Millar, Graeme J

    The Science of the total environment

    2020  Volume 757, Page(s) 144152

    Language English
    Publishing date 2020-12-10
    Publishing country Netherlands
    Document type Published Erratum
    ZDB-ID 121506-1
    ISSN 1879-1026 ; 0048-9697
    ISSN (online) 1879-1026
    ISSN 0048-9697
    DOI 10.1016/j.scitotenv.2020.144152
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  10. Article: Rainfall isotope variations over the Australian continent – Implications for hydrology and isoscape applications

    Hollins, Suzanne E / Hughes, Catherine E / Crawford, Jagoda / Cendón, Dioni I / Meredith, Karina T

    Science of the total environment. 2018 Dec. 15, v. 645

    2018  

    Abstract: This paper presents a continental scale interpretation of δ2H and δ18O in Australian precipitation, incorporating historical GNIP data at seven sites (1962–2002) and 8–12 years of new monthly data from 15 sites from 2003 to 2014. The more than doubling ... ...

    Abstract This paper presents a continental scale interpretation of δ2H and δ18O in Australian precipitation, incorporating historical GNIP data at seven sites (1962–2002) and 8–12 years of new monthly data from 15 sites from 2003 to 2014. The more than doubling of stations and the significant time series duration allow for an improved analysis of Australian precipitation isotopes. Local meteoric water lines were developed for each site, and for the Australian continent. When the annual precipitation weighted values were used, the Australian meteoric water line was δ2H = 8.3 δ18O + 14.1‰.Precipitation amount was found to be a stronger driver of precipitation isotopes than temperature at most sites, particularly those affected by tropical cyclones and the monsoon. Latitude, elevation and distance from the coast were found to be stronger drivers of spatial variability than temperature or rainfall amount.Annual isoscapes of δ2H, δ18O and deuterium excess were developed, providing an improved tool to estimate precipitation isotope inputs to hydrological systems. Because of the complex climate, weather and oceanic moisture sources affecting Australia, regional groupings were used instead of the climate zone approach and additional data was included to improve the coverage in data poor regions. Regression equations for the isoscape were derived using latitude, altitude and distance from the coast as predictor variables.We demonstrate how this isoscape can be used as a tool for interpreting groundwater recharge processes using examples from across Queensland and New South Wales, including the Murray Darling Basin. Groundwater isotopes at sites where direct local recharge occurs are similar to rainfall, but for inland sites, which are often arid or semi-arid, a disconnect between shallow groundwater and local rainfall is observed; the departure in deuterium excess for these sites increases with aridity and distance from the headwaters where flooding originates.
    Keywords altitude ; basins ; climatic zones ; coasts ; deuterium ; dry environmental conditions ; equations ; groundwater ; groundwater recharge ; hurricanes ; latitude ; monsoon season ; oxygen ; rain ; stable isotopes ; temperature ; time series analysis ; New South Wales ; Queensland
    Language English
    Dates of publication 2018-1215
    Size p. 630-645.
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 121506-1
    ISSN 1879-1026 ; 0048-9697
    ISSN (online) 1879-1026
    ISSN 0048-9697
    DOI 10.1016/j.scitotenv.2018.07.082
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