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Cheng KH, Luo X, Jiao JJ, Yu S. Storm accelerated subsurface Escherichia coli growth and exports to coastal waters. JOURNAL OF HAZARDOUS MATERIALS 2023; 441:129893. [PMID: 36084468 DOI: 10.1016/j.jhazmat.2022.129893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 08/11/2022] [Accepted: 08/30/2022] [Indexed: 06/15/2023]
Abstract
Storm significantly deteriorates coastal water fecal pollution now and beyond. Questions relating to storm exerting on coastal water safety are often intertwined with both surface water and subsurface processes. Stormwater runoff is a vital metric for coastal water fecal pollution under current cognition, while the controls of subsurface system remain unclear. Here, this study leveraged two time-series field data collected in a sandy beach during storm and non-storm periods to probe subsurface Escherichia coli (E. coli) growth and exports to coastal waters under storm events. Results demonstrated that storm events can not only stimulate subsurface E. coli growth, but also accelerate subsurface E. coli exports into the receiving water. Storm-intensified rainfall injected more oxygenous rainwater in the shallow groundwater, subsequently stimulating subsurface E. coli growth. Storm-strengthened wave energy was responsible for accelerating subsurface E. coli exports through enhanced wave-induced recirculated seawater. This study proposes a new insight for the stress of storm events on microbial pollution in coastal waters. The findings are constructive to the prevention of beach ecosystem pollution and can pave the way for coastal safety management to future extreme weather.
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Affiliation(s)
- K H Cheng
- Department of Earth Sciences, The University of Hong Kong, Hong Kong, China; School of Biological Sciences, The University of Hong Kong, Hong Kong, China
| | - Xin Luo
- Department of Earth Sciences, The University of Hong Kong, Hong Kong, China; Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai, China.
| | - Jiu Jimmy Jiao
- Department of Earth Sciences, The University of Hong Kong, Hong Kong, China; Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai, China
| | - Shengchao Yu
- Department of Earth Sciences, The University of Hong Kong, Hong Kong, China
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Cheng KH, Luo X, Jiao JJ, Yu S. Delineating E. coli occurrence and transport in the sandy beach groundwater system by radon-222. JOURNAL OF HAZARDOUS MATERIALS 2022; 431:128618. [PMID: 35278964 DOI: 10.1016/j.jhazmat.2022.128618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 01/24/2022] [Accepted: 02/28/2022] [Indexed: 06/14/2023]
Abstract
Fecal pollution poses a global threat to environmental safety and ecosystem, but the mechanism of microbial transport and occurrence in the beach groundwater system is still poorly explored. Here, we leveraged one-year field data of Escherichia coli (E. coli) and radon-222 (222Rn) and found that E. coli occurrence and transport in the sandy beach groundwater system can be delineated by 222Rn. The underlying mechanism behind this phenomenon is due to similar half-lives of 222Rn and E. coli in the sandy beach groundwater system. Thus, the unique relationship between 222Rn and E. coli can provide additional critical context to the microbial water quality assessments and ecosystem resilience. Also, the beach aquifer in this study is found to be a vital compartment for E. coli removal. The net E. coli removal/production capacity is identified to be highly impacted by submarine groundwater discharge. Finally, a conceptual model is constructed for a better understanding of the occurrences and characteristics of E. coli and 222Rn at multiple spatial scales. These findings are constructive to mitigate the hazardous influences of microbe on water quality, especially in recreational sandy beaches and mariculture zones.
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Affiliation(s)
- K H Cheng
- Department of Earth Sciences, The University of Hong Kong, Hong Kong, China
| | - Xin Luo
- Department of Earth Sciences, The University of Hong Kong, Hong Kong, China.
| | - Jiu Jimmy Jiao
- Department of Earth Sciences, The University of Hong Kong, Hong Kong, China
| | - Shengchao Yu
- Department of Earth Sciences, The University of Hong Kong, Hong Kong, China
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A Novel Hybrid Model for Developing Groundwater Potentiality Model Using High Resolution Digital Elevation Model (DEM) Derived Factors. WATER 2021. [DOI: 10.3390/w13192632] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The present work aims to build a unique hybrid model by combining six fuzzy operator feature selection-based techniques with logistic regression (LR) for producing groundwater potential models (GPMs) utilising high resolution DEM-derived parameters in Saudi Arabia’s Bisha area. The current work focuses exclusively on the influence of DEM-derived parameters on GPMs modelling, without considering other variables. AND, OR, GAMMA 0.75, GAMMA 0.8, GAMMA 0.85, and GAMMA 0.9 are six hybrid models based on fuzzy feature selection. The GPMs were validated by using empirical and binormal receiver operating characteristic curves (ROC). An RF-based sensitivity analysis was performed in order to examine the influence of GPM settings. Six hybrid algorithms and one unique hybrid model have predicted 1835–2149 km2 as very high and 3235–4585 km2 as high groundwater potential regions. The AND model (ROCe-AUC: 0.81; ROCb-AUC: 0.804) outperformed the other models based on ROC’s area under curve (AUC). A novel hybrid model was constructed by combining six GPMs (considering as variables) with the LR model. The AUC of ROCe and ROCb revealed that the novel hybrid model outperformed existing fuzzy-based GPMs (ROCe: 0.866; ROCb: 0.892). With DEM-derived parameters, the present work will help to improve the effectiveness of GPMs for developing sustainable groundwater management plans.
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Methods in Capturing the Spatiotemporal Dynamics of Flow and Biogeochemical Reactivity in Sandy Beach Aquifers: A Review. WATER 2021. [DOI: 10.3390/w13060782] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Sandy beach aquifers are complex hydrological and biogeochemical systems where fresh groundwater and seawater mix. The extent of the intertidal mixing zone and the rates of circulating flows within beaches are a primary control on porewater chemistry and microbiology of the intertidal subsurface. Interplay between the hydrological and biogeochemical processes at these land-sea transition zones moderate fluxes of chemicals, particulates, heavy metals, and biota across the aquifer-ocean interface, affecting coastal water quality and nutrient loads to marine ecosystems. Thus, it is important to characterize hydrological and biogeochemical processes in beach aquifers when estimating material fluxes to the ocean. This can be achieved through a suite of cross-disciplinary measurements of beach groundwater flow and chemistry. In this review, we present measurement approaches that have been developed and employed to characterize the physical (geology, topography, subsurface hydrology) and biogeochemical (solute and particulate distributions, reaction rates) properties of and processes occurring within sandy intertidal aquifers. As applied to beach systems, we discuss vibracoring, sample collection, laboratory experiments, variable-density considerations, instrument construction, and sensor technologies. We discuss advantages and limitations of typical hydrologic field sampling methods when used to investigate beach aquifers and provide a measurement framework for researchers seeking to sample and collect data from these systems.
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Liang W, Liu Y, Jiao JJ, Luo X. The dynamics of dissolved inorganic nitrogen species mediated by fresh submarine groundwater discharge and their impact on phytoplankton community structure. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 703:134897. [PMID: 31731157 DOI: 10.1016/j.scitotenv.2019.134897] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 10/07/2019] [Accepted: 10/07/2019] [Indexed: 06/10/2023]
Abstract
Submarine groundwater discharge (SGD)-driven nutrient inputs have long been speculated to sustain the high frequency of red tide occurrence in Tolo Harbour, Hong Kong, for its larger flux and higher nutrient loadings than river discharge. Based on analysis of high resolution time series biogeochemical and climatological data from 2000 to 2015, fresh SGD-derived dissolved inorganic nitrogen (DIN) is found to be a significant regulator of the annual cycle of phytoplankton community structure in the harbour. In the wet season, fresh SGD supplies nutrients with NH4+:NO3- ratio < 1 to the seawater, meanwhile creates an intensive vertical stratification environment. As a result, diatom which is a NO3- specialist, is prone to be the major group in the harbour. Fresh SGD delivers a same orders of magnitude of DIN as river and precipitation, but it is more important to phytoplankton community structure dynamics because fresh groundwater has smaller NH4+:NO3- ratio that significantly changes the ratio in the harbour. In the dry season, with the decline of fresh SGD and the ease of stratification, vertical mixing uplifts the nutrient (NH4+:NO3- ratio > 1) released from the bottom sediment leading to a NH4+ dominant environment in water column. Dinoflagellate and other groups then become dominant species of phytoplankton in the harbour. Fresh SGD has a major influence on the NH4+:NO3- ratio in the seawater compared to tide-driven SGD, even though the latter contributes a larger proportion SGD. Tide-driven SGD also produces NH4+ and NO3-, but NH4+:NO3- ratio are mainly subject to the beach environment (bare/mangrove beach), which does not change much seasonally, thus dominant DIN species do not change significantly throughout a year. In a conclusion, fresh SGD plays the most important role among all the endmembers in regulating the DIN composition in Tolo Harbour and its fluctuation mediates the phytoplankton community structure.
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Affiliation(s)
- Wenzhao Liang
- Department of Earth Sciences, University of Hong Kong, Pokfulam Road, Hong Kong, China; Shenzhen Research Institute, The University of Hong Kong, Shenzhen, China.
| | - Yi Liu
- Department of Earth Sciences, University of Hong Kong, Pokfulam Road, Hong Kong, China; Shenzhen Research Institute, The University of Hong Kong, Shenzhen, China; Department of Civil and Environmental Engineering, Western University, London, Ontario, Canada.
| | - Jiu Jimmy Jiao
- Department of Earth Sciences, University of Hong Kong, Pokfulam Road, Hong Kong, China; Shenzhen Research Institute, The University of Hong Kong, Shenzhen, China.
| | - Xin Luo
- Department of Earth Sciences, University of Hong Kong, Pokfulam Road, Hong Kong, China; Shenzhen Research Institute, The University of Hong Kong, Shenzhen, China.
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Liu Y, Not C, Jiao JJ, Liang W, Lu M. Tidal induced dynamics and geochemical reactions of trace metals (Fe, Mn, and Sr) in the salinity transition zone of an intertidal aquifer. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 664:1133-1149. [PMID: 30901786 DOI: 10.1016/j.scitotenv.2019.01.374] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 01/16/2019] [Accepted: 01/16/2019] [Indexed: 06/09/2023]
Abstract
Biogeochemical reactions in an intertidal aquifer influences the submarine groundwater discharge (SGD) associated trace metal flux to the ocean. Tidal fluctuation greatly affects the physical mixing, and biogeochemical transformation of trace metals in the intertidal aquifer. This study presents the dynamics of trace metals (Fe, Mn, and Sr) and the production of Fe2+ in the salinity transition zone is discovered. The variations of Fe2+ are led by the shifts of both physical mixing and biogeochemical reaction during tidal fluctuation. The transformation from amorphous Fe(OH)3 to FeS is the main reason for the enrichment of Fe2+ in the zone with a salinity of 0.5-10. Mn behaves much less active than Fe in the intertidal aquifer due to the very limited Mn in the solid phase and the major driving force of Mn2+ variation is the physical mixing rather than geochemical reaction. Sr2+ behaves conservatively and shows a synchronous with salinity in the salinity transition zone. This study found that Fe2+ precipitates in a form not limited to Fe (hydro)oxides and the FeS minerals is the most possible form of precipitation in reduced aquifers. In that case, only a small part of Fe2+ discharges to the sea associated with SGD, but Mn2+ has a comparatively conservative property during the transport in the intertidal aquifer and majority of the Mn2+ originated from fresh groundwater will discharge with SGD in this study. The biogeochemical transformation pathways of Fe and Mn observed in this study provides insights into the cycles of Fe and Mn in an intertidal aquifer, which is of significance to accurately estimate the SGD derived Fe and Mn fluxes to the ocean.
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Affiliation(s)
- Yi Liu
- Department of Earth Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China; Shenzhen Research Institute, The University of Hong Kong, Shenzhen, China.
| | - Christelle Not
- Department of Earth Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China; The Swire Institute for Marine Science, The University of Hong Kong, Cap d'Aguilar, Hong Kong, China
| | - Jiu Jimmy Jiao
- Department of Earth Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China; Shenzhen Research Institute, The University of Hong Kong, Shenzhen, China.
| | - Wenzhao Liang
- Department of Earth Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China; Shenzhen Research Institute, The University of Hong Kong, Shenzhen, China
| | - Meiqing Lu
- Department of Earth Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China
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Luo X, Jiao JJ, Moore WS, Cherry JA, Wang Y, Liu K. Significant chemical fluxes from natural terrestrial groundwater rival anthropogenic and fluvial input in a large-river deltaic estuary. WATER RESEARCH 2018; 144:603-615. [PMID: 30096687 DOI: 10.1016/j.watres.2018.07.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 06/12/2018] [Accepted: 07/03/2018] [Indexed: 06/08/2023]
Abstract
The shores of the Pearl River estuary are home to 35 million people. Their wastes are discharged into the large river delta-front estuary (LDE), one of the most highly polluted systems in the world. Here we construct a radium reactive transport model to estimate the terrestrial groundwater discharge (TGD) into the highly urbanized Pearl River LDE. We find the TGD comprises only approximately 0.9% in term of water discharge compared to the river discharge. The TGD in the Pearl River LDE delivers significant chemical fluxes to the coast, which are comparable to the fluvial loadings from Pearl River and other world major rivers. Of particular importance is the flux of ammonium because of its considerable role in Pearl River estuary eutrophication and hypoxia. Unlike the ammonium in many other aquifers, the ammonium in the Pearl River aquifer system is natural and originated from organic matter remineralization by sulfate reduction in the extremely reducing environment. The TGD derived NH4+ is as much as 5% of the upstream Pearl River fluvial loading and 42% of the anthropogenic inputs. This high groundwater NH4+ flux may greatly intensify the eutrophication, shift the trophic states, and lead to alarming hypoxia within the affected ecosystems in the Pearl River LDE. The large TGD derived chemical fluxes will lead to deterioration of water and will potentially affect human health.
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Affiliation(s)
- Xin Luo
- Department of Earth Sciences, The University of Hong Kong, PR China; The University of Hong Kong, Shenzhen Research Institute (SRI), Shenzhen, PR China; The University of Hong Kong-Zhejiang Institute of Research and Innovation (HKU-ZIRI), Hangzhou, PR China
| | - Jiu Jimmy Jiao
- Department of Earth Sciences, The University of Hong Kong, PR China; The University of Hong Kong, Shenzhen Research Institute (SRI), Shenzhen, PR China; The University of Hong Kong-Zhejiang Institute of Research and Innovation (HKU-ZIRI), Hangzhou, PR China.
| | - Willard S Moore
- Department of Earth and Ocean Sciences, University of South Carolina, Columbia, 29208, SC, USA
| | - John A Cherry
- School of Engineering, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Ya Wang
- School of Earth Science and Geological Engineering, Sun Yat-sen University Guangzhou, 510275, PR China
| | - Kun Liu
- China Institute of Geo-Environment Monitoring, China Geological Survey, PR China
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Assessing Aquifer Salinization with Multiple Techniques along the Southern Caspian Sea Shore (Iran). WATER 2018. [DOI: 10.3390/w10040348] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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