Browsing by Author "Jones, OAH"

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    Combining environmental isotopes with contaminants of emerging concern (CECs) to characterise wastewater derived impacts on groundwater quality
    (Elsevier B.V., 2020-09-01) McCance, WG; Jones, OAH; Cendón, DI; Edwards, M; Surapaneni, A; Chadalavada, S; Wang, S; Currell, MJ
    The potential for Wastewater Treatment Plants (WWTPs) to cause adverse impacts to groundwater quality is a major global environmental challenge. Robust and sensitive techniques are required to characterise these impacts, particularly in settings with multiple potential contaminant sources (e.g. agricultural vs. site-derived). Stable (δ2HH2O, δ18OH2O, δ15NNO3, δ18ONO3 and δ13CDIC) and radioactive (3H and 14C) isotopes were used in conjunction with three Contaminants of Emerging Concern (CECs) - carbamazepine, simazine and sulfamethoxazole - to discriminate between multiple potential contamination sources at an Australian WWTP. The radioactive isotope tritium provided a sensitive indicator of recent (post-1990s) leakage, with groundwater activities between 0.68 and 1.83 TU, suggesting WWTP infrastructure (activities between 1.65 and 2.41) acted as a recharge ‘window’, inputting treated or partially treated effluent to the underlying groundwater system. This was corroborated by water stable isotopes, which showed clear demarcation between δ18OH2O and δ2HH2O in background groundwater (δ18OH2O and δ2HH2O values of approximately −5 and −28‰, respectively) and those associated with on-site wastewater (median δ18OH2O and δ2HH2O values of −1.2 and −7.6‰, respectively), with groundwater down-gradient of the plant plotting on a mixing line between these values. The CECs, particularly the carbamazepine:simazine ratio, provided a means to further distinguish wastewater impacts from other sources, with groundwater down-gradient of the plant reporting elevated ratios (median of 0.98) compared to those up-gradient (median of 0.11). Distinctive CEC ratios in impacted groundwater close to the WWTP (∼3.0) and further down-gradient (2.7–9.3) are interpreted to represent a change in composition over time (i.e., recent vs. legacy contamination), consistent with the site development timeline and possible changes in effluent composition resulting from infrastructure upgrades over time. The data indicate a complex set of co-mingled plumes, reflecting different inputs (in terms of both quantity and concentration) over time. Our approach provides a means to better characterise the nature and timing of wastewater derived impacts on groundwater systems, with significant global implications for site management, potentially allowing more targeted monitoring, management and remedial actions to be undertaken. © 2020 Elsevier B.V.
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    Decoupling wastewater impacts from hydrogeochemical trends in impacted groundwater resources
    (Elsevier B. V., 2021-06-20) McCance, WG; Jones, OAH; Cendón, DI; Edwards, M; Surapaneni, A; Chadalavada, S; Currell, MJ
    In the urban environment, anthropogenic activities provide numerous potential sources of contamination, which can often lead to difficulties in identifying the processes impacting groundwater quality (natural and anthropogenic). This is particularly relevant at Wastewater Treatment Plants (WWTPs) that are often subject to changes in land use and composition of contaminant sources over time and space, as well as multiple potential hydrogeochemical interactions. To help address this issue, we demonstrate how long-term time-series analysis of major ions and key contaminants of concern, which are routinely collected by WWTP operators, can be analysed using hydrogeochemical plotting tools, multivariate statistics and targeted isotopic analysis, to provide a means of better characterising key hydrogeochemical influences and anthropogenic inputs. Application of this approach to a WWTP in south-eastern Australia indicated that anthropogenic impacts were the primary driver influencing the local hydrogeochemical environment and groundwater quality. However, secondary processes, including mineral (particularly calcite) dissolution, ion exchange and possible dedolomitisation, as well as natural degradation/transformation of contaminants were also important. Long-term, time-series analysis of trends in NO3-N, NH4-N, Ca2+, SO42−, HCO3− and K+ in conjunction with the other lines of evidence, allowed for enhanced separation between individual contaminant sources, particularly when paired with a detailed site history and Conceptual Site Model (CSM). This indicated that off-site agricultural impacts post-date most site derived impacts, and to date, have not significantly added to the identified contaminant plume. The outcomes of this work have significant global application in the identification, assessment, and control of environmental and health risks at complex sites and show how significant value (rarely obtained) can be derived from the analysis of routine monitoring datasets, particularly when analysed using a multiple lines of evidence approach. © 2021 Elsevier B.V.
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    Use of stable and radiogenic isotopes in characterising wastewater derived impacts in Urban and Peri-Urban areas
    (National Centre for Groundwater Research And Training, & Australian Chapter International Association Of Hydrogeologists, 2019-11-24) McCance, WG; Jones, OAH; Edwards, M; Surapaneni, A; Chadalavada, S; Cendón, DI; Currell, MJ
    Objectives: This study focuses on one of South East Water’s Water Recycling Plants (WRPs), located adjacent to an area of significant agricultural activity (market gardens), where multiple potential sources of groundwater contamination (nutrients) have been identified. The primary objective was to examine the use of stable and radiogenic isotopes in conjunction with contaminants of emerging concern (e.g. pharmaceuticals) to gain a greater understanding of the underlying hydrogeochemical processes and separate wastewater-derived contamination from other potential sources e.g., agriculture. Design and methodology: This project combined long term groundwater monitoring data (collected since 1997) with in-situ isotopic tracers sampled in 2018-2019 including: δ2HH2O and δ18OH2O, δ13CDIC, 3H and 14C, analysed at ANTSO’s Lucas Heights facility, and δ18ONO3 and δ15NNO3, analysed at China’s Key Laboratory of Agricultural Water Resources. The isotopic data were combined with other lines of evidence, including contaminants of emerging concern (e.g. pharmaceuticals) analysed at RMIT, as an additional metric to better delineate wastewater impacts in a mixed source environment. Original data and results: Groundwater residence time indicators from groundwater wells located adjacent to or upgradient of the treatment plant, contain 14C and 3H activities (>73 pMC and >0.68 TU) which indicate a large component of modern recharge (i.e. <50 years old). Groundwater near suspected leaky infrastructure contains elevated levels of these radiogenic isotopes compared to those considered more indicative of background conditions (>97 pMC and >1.4 TU compared to 72-85 pMC and 0.68-1.03 TU, respectively), indicating potential anthropogenic inputs. Water stable isotopes, plot along a mixing line between regional groundwater (e.g. outside the known plume) and evaporated groundwater (e.g. recharge from former and current sludge lagoons). End-member mixing calculations indicate a significant proportion of effluent in groundwater downgradient of treatment infrastructure. Elevated nutrient concentrations in groundwater occur throughout the region (e.g., 0.6 to 160 mg/L nitrogen (total)). Nitrate isotopes show clear differences between nutrients derived from agriculture (values between 5 and 29‰, median = 12.0‰), and those impacted by the treatment plant (values between 2.9 and 41.2 ‰, median = 18.0‰), with effluent values between 20.2‰ and 39.1‰). Further work is being undertaken to quantify pharmaceuticals as an additional metric to better delineate wastewater impacts. Conclusions : The findings show how isotopic tracers can assist in overcoming the difficulties associated with delineating multiple similar contamination sources. This will enable wastewater treatment plant operators to more accurately assess and manage their impacts on groundwater. © The Authors