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Genetic and molecular basis of organic-arsenic-microbe interactions in arsenic prone aquifers (GOAM)

Lead Research Organisation: University of Manchester
Department Name: Earth Atmospheric and Env Sciences

Abstract

Contamination of groundwater from naturally occurring arsenic (As) in the subsurface poses a global public health crisis in countries including Mexico, China, Hungary, Argentina, Chile, Cambodia, India (West Bengal), and Bangladesh and has been termed "the largest mass poisoning" in human history. The mechanism of arsenic release from these sediments has been a topic of intense international debate. However, microbially-mediated reduction of assemblages comprising arsenic (most likely as arsenate) sorbed to ferric oxyhydroxides has gained consensus as the most likely method of mobilization of arsenic into these groundwaters, although the precise mechanism of release remains to be identified. Critical questions that remain include (i) the identity of the organisms that catalyse the process; (ii) the physiological mechanism that leads to electron transfer to the extracellular Fe/As mineralogical assemblage; (iii) the nature (and delivery route) of the organic material that activates metal reduction and release; and (iv) the interplay between other competing processes such as oxidation, sulfidation and sorption that can attenuate the process in situ. By focusing the combination of cutting edge microbiological, high throughput molecular ecology (meta-omics), geochemical and mineralogical techniques against samples obtained directly from two contrasting field sites with high arsenic groundwaters, GOAM is a hypothesis driven research programme that aims to identify the critical molecular scale factors causing this environmental disaster, while informing strategies to minimise their impact. A mature network of international collaborations will underpin our field related activities, transfer of molecular scale data to inform hydrogeochemical models and subsequent knowledge exchange with key stakeholders in countries including Bangladesh and Cambodia.

Planned Impact

The research outcomes will be of interest to academic beneficiaries (as noted above) and also, groundwater resource stakeholders (Government and non-government organisations who have responsibilities, authority and/or interests in protecting public health in the regions impacted) and the wider general public, including those in regions impacted by groundwater arsenic, whom we have a particular responsibility to reach out to.

We will use a range of activities tailored to best effectively impact the different major target groups. For example academic researchers will benefit from high profile of this work will be maintained by publications in high quality peer-reviewed journals, presentations at (inter)national scientific meetings and publishing our results on the University of Manchester and, as appropriate, our project partners websites. If possible, the samples of drill-core and/or well waters will be made available to other suitable collaborating scientists with access to complementary techniques and/or research questions. We will also archive our data following standards for the storage and retention of data set by the University of Manchester Code of Good Research Conduct and make sure that data can be widely and transparently accessed. As appropriate, we will provide copies of our data to a NERC or other institute site.

We will email/write to groundwater resource stakeholders, particularly in Cambodia, Bangladesh and elsewhere in circum-Himalayan Asia, with lay summaries of our key findings. We will also make further personal contacts with key government and non-government organisation officers to highlight key relevant findings and through a short workshop in Cambodia and/or Bangladesh in the final year of the project. To achieve this, networking links and collaborations established through the recently completed NERC NE/J023833/1 project in Cambodia, as well as the AquaTRAIN MRTN (pan European), EU Asia-Link CALIBRE (South-East Asia) and UKIERI PRAMA (India) networks will be used (all led from Manchester), in addition to the mature networks into Bangladesh developed by our colleagues in Columbia.

A website will also be established with content specifically targeted at non-science readers in arsenic impacted regions & in the UK. The key components will be to give a description of our approach, the methods used and the results obtained in a user-friendly and accessible way. All educational material as a result of other activities, such as the workshop, our UK outreach programme and the video (see below), will be made freely available through this website.
We will also produce press releases describing key research results will be communicated in lay terms through press releases via the University Press Office (after, as appropriate, liaising with the NERC press office) and through other media, including TV and radio. The PDRA/PI/Co-Is will participate in a number of public events, including the Science Showcase week at University of Manchester (one of the most extensive outreach programmes of any UK university), lecturing (through a programme open to all ages) at The Manchester Museum and/or assisting in running workshops on public engagement in Science.

Finally we deliver targeted outreach programmes in Cambodia, in collaboration with our local university partner RUPP and other local partners, building upon knowledge exchange activities already undertaken as part of NE/J023833/1 (including an international workshop in Phnom Penh which drew participants from local, provincial, national and international levels, as well as a short-course on environmental training for local university students) and activities already undertaken as part of the EU Asia-Link CALIBRE Project. We will also participate in parallel activities in Bangladesh organised by our US collaborators.

Publications

10 25 50

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Macaulay BM (2020) A Novel "Microbial Bait" Technique for Capturing Fe(III)-Reducing Bacteria. in Frontiers in microbiology

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Xie J (2023) Microbial Reduction of Antimony(V)-Bearing Ferrihydrite by Geobacter sulfurreducens. in Applied and environmental microbiology

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Xiu W (2024) Ammonium-Enhanced Arsenic Mobilization from Aquifer Sediments. in Environmental science & technology

 
Description The objectives below were met fully and papers are now in press detailing the key findings. These include identification of impacts of seasonal changes in hydrology on microbial community structure and As release, verification of novel bait techniques to study in situ biogeochemical process, discovery of new indirect methane-driven As-release biogeochemical process, identification of alternative (ammonium-driven) As-release processes, and advanced metagenomic analysis of systems above identifying key organisms and genetic underpinnings.



1. Analyse filtered groundwaters, sediments, retrieved (As/Fe) mineral baits and microcosm communities using high
throughput DNA sequencing, amplifying 16S rRNA phylogenetic markers, alongside targeted metagenomic and proteomic
analyses (including stable isotope probing approaches) to identify the causative microorganisms and metabolic processes
underpinning As-release;
2. Quantify inorganic (e.g. IC-ICP-MS for As speciation) and organic (e.g. IC, GC-MS, FTIR and FTICR-MS) components of
groundwaters from the field sites and microcosms to determine the impact of microbial metabolism on trace metal
biogeochemistry (including arsenic release) and the identity of the organic materials (electron donor) driving Fe/As redox
transformations. Particular focus will be on the extraction and analysis of organics captured from the groundwaters using
novel Fe/As-coated baits, and their subsequent metabolism;
3. Perform mineralogical analyses using WRC (e.g. XRD, fluorescence/confocal microscopy, ESEM/Raman/XRF,
Mossbauer, TEM, NanoSIMS) and DLS (e.g. XAS and STXM) imaging and spectroscopy/spectromicroscopy techniques
applied to pristine and retrieved mineral baits to identify the nano-scale interactions of extant microbes with iron
oxyhydroxide phases in high arsenic aquifers;
4. Construct a nano-scale conceptual model showing the microbes, genes and proteins responsible for arsenic release, the
key organic components driving the system and the mineralogical constraints controlling As release and sorption.
Exploitation Route This work is helping support several ongoing international research programmes and a future leader programme led by one of the research team.
Sectors Agriculture

Food and Drink

Environment

Healthcare

URL https://doi.org/10.1016/j.orggeochem.2024.104886
 
Title Gas composition in headspace of borehole NB04, Cambodia, southeast of Phnom Penh, 2019 - 2020 
Description Data on gas composition in headspace of borehole NB04. Contains 11 columns of data taken from the headspace of borehole NB04 (at the clay-dominated site) using a GasClam 2.0 (Salamander Group, UK) that continuously measure temperature, atmospheric pressure, borehole pressure, and the percentage of carbon dioxide, oxygen, and methane in the borehole. All data collection for the GOAM project was performed on the same sites located in the Kien Svay district of northern Kandal Province, Cambodia, southeast of Phnom Penh. These sites are referred to as "clay-dominated" and "sand-dominated" in reference to the known lithology and are known for high arsenic concentrations (Richards et al., 2017). Each site contained four 18 m boreholes installed in January 2019 using manual drilling described in Richards et al (2015), spaced evenly about ~1.5 m apart. The boreholes that were located at the clay-dominated site are referred to NB01, NB02, NB03 and NB04. The boreholes that were located at the sand-dominated site are referred to as NB05, NB06, NB07 and NB08. The data taken are from the headspace of borehole NB04 (at the clay-dominated site) This file contains part of the data produced for NERC grant NE/P01304X/1 - called Genetic and molecular basis of organic-arsenic-microbe interactions in arsenic prone aquifers ("GOAM") project. 
Type Of Material Database/Collection of data 
Year Produced 2024 
Provided To Others? Yes  
URL https://www2.bgs.ac.uk/nationalgeosciencedatacentre/citedData/catalogue/6e7552ec-1636-4e0e-9531-1ba8...
 
Title Groundwater geochemical data from two sites in Cambodia, southeast of Phnom Penh, 2019 - 2020 
Description These are groundwater geochemical data taken from two sites in the Kien Svay district of northern Kandal Province, Cambodia, southeast of Phnom Penh. These sites are referred to as "clay-dominated" and "sand-dominated" in reference to the known lithology and are known for high arsenic concentrations (Richards et al., 2017). Each site contained four 18 m boreholes installed in January 2019 using manual drilling described in Richards et al (2015), spaced evenly about ~1.5 m apart. The boreholes that were located at the clay-dominated site are referred to NB01, NB02, NB03 and NB04. The boreholes that were located at the sand-dominated site are referred to as NB05, NB06, NB07 and NB08. Two sampling campaigns were carried out: 6th-12th May 2019 (pre-monsoon season), and 27th-31st January 2020 (post-monsoon season). This file contains part of the data produced for NERC grant NE/P01304X/1 - called Genetic and molecular basis of organic-arsenic-microbe interactions in arsenic prone aquifers ("GOAM") project. 
Type Of Material Database/Collection of data 
Year Produced 2024 
Provided To Others? Yes  
URL https://www2.bgs.ac.uk/nationalgeosciencedatacentre/citedData/catalogue/6bb55fd0-c4ef-4044-8acc-d664...
 
Title NanoSIMS imaging of extracellular electron transport processes during microbial iron(III) reduction 
Description Geochemical and NanoSIMS data for "NanoSIMS imaging of extracellular electron transport processes during microbial iron(III) reduction" 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
URL https://data.mendeley.com/datasets/gppn7stysx/1
 
Description Invited talk at International Workshop on Organic-Water-Rock Interaction (OWRI 2023) Beijing 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Impact of microbial  metabolism on trace element fate International Workshop on Organic-Water-Rock Interaction (OWRI 2023) 24th November 2023 - Geosciences International Conference Centre, Beijing
Year(s) Of Engagement Activity 2023
 
Description Outreach visit to International University, Phnom Penh, Cambodia to discuss work on Arsenic poisoning of groundwaters in Cambodia 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Undergraduate students
Results and Impact Outreach to 40+ students on "Introduction to Environmental Microbiology" Faculty of Science and Technology, International University, Phnom Penh, Cambodia. 23rd Jan 2023
Year(s) Of Engagement Activity 2023