2018 – Hydrogeochemistry of trace elements and human health: from the water table to the kitchen table
| The 2018 Ineson Lecture was presented by Dr Pauline Smedley, Principal Hydrogeochemist at the British Geological Survey. Dr Smedley is a world renowned Hydrogeochemist with an extensive publication history. She was supported by leading UK speakers addressing the geochemical issues we face today with our potable groundwater supplies and potential impacts on human health.
Speaker abstracts:
Medical Hydrogeology of Asian Deltas – Do We Need an Holistic Approach to Water Quality? Groundwater, a drinking water source for more than 70% of inhabitants living in Asian deltas, has received much attention because of its naturally occurring arsenic, but the coupling or decoupling of arsenic toxicity with other water constituents remains unexplored. In addition, although nutrients are generally provided by food, in under developed rural settings, where people subsist on low nutrient diets, drinking‐water‐nutrients may supply quantities vital to human health thereby preventing disease. Using Bangladesh as a case study, we show that the chemical content of groundwater is such that in some areas individuals obtain up to 50% or more of the recommended daily intake (RDI) of some nutrients (e.g., calcium, magnesium, iron) from just two litres of drinking water. We therefore suggest that an understanding of the association of non‐communicable disease and poor nutrition cannot be developed, particularly in areas with high levels of dissolved solids in water sources, without considering the contribution of drinking water to nutrient and mineral supply.
Emerging Contaminants in Groundwater: A Health Risk? Marianne Stuart¹* The investigation of emerging organic contaminants in groundwater has expanded rapidly over the last two decades. Earlier studies highlighted the wide distribution of compounds such as pesticides, chlorinated solvents, polyaromatic hydrocarbons and phthalate plasticisers, and many of these have now been regulated. Additionally, surfactants such as alkyl ethoxylates and linear alkyl sulfonates have been implicated as endocrine disruptors. However, the continued development of analytical methods has meant we can now detect thousands of other microorganic compounds. In England and Wales, we have seen the widespread detection of pesticide metabolites, and emerging contaminants, such as caffeine, DEET and bisphenol A, personal care products and industrial precursors. More recent work on polar compounds has shown a wide range of pharmaceuticals (e.g., carbamazepine, clopidol and sulfamethoxazole) also to be present, albeit at typically very low concentrations. Like many contaminants, concentrations are controlled by both the source term and seasonal attenuation processes, and concentrations can be variable. It remains unclear what the risk to human health from drinking water, and also to the environment, from the very low concentrations detected in groundwater. There are as yet few methodologies which assess compounds both in terms of persistence and mobility in the environment and in health risks in order to set health limits or threshold concentrations in groundwater.
Mitigating Groundwater Arsenic Poisoning in the Bengal Basin Peter Ravenscroft¹* Since the discovery of arsenic contamination of groundwater in Bangladesh in the mid-1990s—and quickly recognised as the world’s worst case of mass chemical poisoning—great strides have been made in scientific understanding of the causes and controls of arsenic contamination; surveying its extent; its impact on health, agriculture, and the economy; and knowledge of which mitigation technologies do and don’t work well. Although there are significant uncertainties concerning inter alia the sustainability of potable abstraction from deep aquifers and irrigation from shallow aquifers, the greatest current concern is that, 20 years after its discovery, the downward trend in the population exposed to arsenic in drinking water is flatlining while exposure via the food chain is increasing. Nevertheless, if the lessons learned to date are applied in practice, there is good reason to expect that unacceptable levels of arsenic exposure from drinking groundwater could be eliminated within a decade and exposure from groundwater-irrigated crops significantly reduced. Further, the risks of arsenic migration within and between shallow and deep aquifers can be mitigated through innovative monitoring and adaptive management.
Forty-Four Years of Groundwater Quality Risk Management with Southern Water Mike Packman¹* Has groundwater quality deteriorated in the last 44 years, or has monitoring just got better and regulation much stricter? Throughout that time over 70 per cent of the water supplied by Southern Water (SW) has come from groundwater, with over 95 per cent from the Chalk aquifer. In 1974 just two per cent of the Chalk sources had treatment other than disinfection, however now it is nearly 50 per cent, ignoring phosphate dosing for plumbosolvency. Hundreds of millions of pounds have been spent on nitrate contamination of groundwater, yet the main reason for source outages in SW is turbidity, as it compromises disinfection. In 1977 SW developed their Aquifer Protection Policy, to provide clear statements on the response to potentially polluting development proposals. This new constructive approach, rather than the often inflexible attitude of continually rejecting proposals, plus good liaison with Local Government (LG), planning and waste disposal staff, proved successful and no appeals were lodged against aquifer protection decisions and no public enquiries held. This, together with Severn Trent’s Policy, formed the basis of the National River Authority’s (NRA) Groundwater Protection Policy (GPP) in 1992. Over one thousand NRA and LG Planning staff were trained in the GPP by myself and two other staff from Southern Science, the SW environmental consultancy. This was followed by a contract to delineate source protection zones (SPZs), mostly using steady state FLOWPATH models. Many SPZs have not been updated since the mid‐1990s, until the recent Water Framework Directive Drinking Water Protection Area work using improved groundwater models and tools to track flow through each cell. This will hopefully assist truly integrated catchment management, which we are starting a pilot scheme on the IOW, involving water, wastewater, regulators, agriculture, environmental groups, waste disposal, industry and local government at all levels.
Hazard and Risk Associated with Manufactured Nanoparticle Release into Matrix‐Flow Dominated UK Aquifer Systems John Tellam¹ and Michael Riley¹* Nanotechnology is advancing at a significant rate resulting in increasing production of nanoparticles (NPs) of a wide range of compositions. Evidence is accumulating of the effects of nanoparticles on organisms, including humans, and in some cases nanoparticles can be viewed as hazardous. Experience indicates that almost invariably industrially produced chemicals are released into groundwaters, and there is limited evidence of manufactured NP presence in some UK groundwaters. Quantifying the risk, however, is not straightforward. NP mobility is affected by several processes, each of which is affected by the aqueous chemistry, especially pH, ionic strength, presence of organic ligands, the surface properties of the rock mass, and the presence of other particles. Models available are of two main types, process‐related and empirical‐kinetic: the former often do not match experimental results well and the latter do not take direct account of changing chemical environments. In the UK, field experiments have been banned for many years, and reliance has had to be placed on laboratory experiments. Column experiments have shown the sensitivity of NP mobility to pH and ionic strength, and insights into the importance of rock surface properties have been demonstrated. However, the number of processes is such that interpreting breakthrough curves is hampered by equivalence. To constrain interpretations, a system of magnetic susceptibility monitoring of NP concentrations within columns has been developed and is providing encouraging results. However, despite much investigation, assessment of the risk in groundwaters from NP contamination lags behind NP production: field experiments need to be undertaken in UK aquifers, and many more laboratory studies are required on UK‐relevant aquifer materials.
Arsenic Hazard in Public Water Supplies in England and Wales: Implications for Exposure, Health and Regulation David A. Polya¹, Lingqian Xu (许伶倩)¹, Yifei Zhang (张艺菲)¹, Qian Li (李芊)¹, Jake Launder¹, Daren C. Gooddy² and Matthew Ascott²* Public water supplies in the UK are highly regulated and monitored and have an outstanding compliance with regulatory standards, particularly with respect to the UK PCV (prescribed concentration value) for arsenic of 10 µg/L. Nevertheless, many UK public water supplies contain arsenic at concentrations within a factor of 10 of the PCV. Given increasing concerns over detrimental health outcomes arising from chronic exposure to drinking water containing arsenic at sub‐regulatory concentrations in the 1–10 µg/L range, quantifying the distribution of arsenic intake from consumers exposed to arsenic via drinking water in the UK is indicated. In 2015, on the order of 10⁵ consumers in the UK were supplied with drinking water with arsenic concentrations at or above 5 µg/L; 10⁶ at or above 2 µg/L and 10⁷ at or above 1 µg/L. Epidemiological evidence seems currently insufficiently powerful to reliably quantify the detrimental health outcomes arising from such sub‐regulatory exposures, but arsenic‐attributable premature avoidable deaths in the UK on the order of 100 to 1000 per annum are plausibly estimated here from combined cancer and cardiovascular disease—these values are considerably less than those ascribed to air pollution but are broadly equivalent to the number of annual fatalities of car occupants in road traffic accidents in England and Wales and warrant concern. Uncertainties and limitations of the approach are discussed together with implications for stakeholders. Acknowledgements: LX acknowledges a University of Manchester President’s PhD Scholarship and JL a NERC CASE (Health and Safety Executive’s Health and Safety Laboratory (HSE’s HSL)) PhD Studentship through the Manchester‐Liverpool NERC EAO DTP. We thank Nick Warren (HSE’s HSL) for statistical advice and Kofi Osuwu for IT support. DCG and MJA publish with the permission of the Executive Director, British Geological Survey (NERC). This abstract is based largely on that presented by DAP at the Arsenic 2018 international meeting in Beijing, People’s Republic of China in July 2018.
Hydrogeochemistry of Trace Elements and Human Health: From the Water Table to the Kitchen Table Pauline Smedley¹* Several decades of research have helped to develop an improved understanding of the occurrence of trace elements of health concern in groundwater used for drinking. Progress has been driven by observations of symptoms, advances in analytical capability and developments in drinking‐water regulation. Today, fluoride and arsenic remain the most significant recognised health‐impacting trace elements in terms of populations exposed. It is estimated that more than 200 million people worldwide are drinking water with fluoride concentrations greater than the internationally accepted standard of 1.5 mg/L, and over 140 million people are exposed to arsenic with concentrations greater than the WHO guideline value of 10 µg/L. Occurrences can be demonstrated from diverse hydrogeological environments, including crystalline bedrock, volcanic terrains and alluvial aquifers, and under varying pH/redox conditions. As new drinking‐water guidelines and regulations have developed, other trace elements including molybdenum, uranium, boron and radon have received increasing focus. Exceedances of these elements in groundwater are much less common but do occur, often in similar hydrogeological settings to those affected by arsenic or fluoride. This presentation will consider the different hydrogeological and hydrogeochemical controls on the occurrences of these trace elements and on their implications for water supply and health. Examples are drawn from personal experiences in Africa, South Asia and the UK.
Poster Abstracts:
Impact of the 2015/16 El Niño Event on Groundwater Resources in Ethiopia R. A. Bell, A. M. MacDonald, S. Kebede, T. Azagegn, D. J. Lapworth, A. A. McKenzie, M. Tayitu The 2015/16 El Niño led to widespread food and water insecurity in Ethiopia, particularly in rural areas where provision of assistance is most difficult. The impact of these extreme climate events on groundwater quality and resources is still poorly understood. Two study areas, Kobo and Lay Gaynt in the Amhara region of Ethiopia were identified and 7 rounds of water quality samples collected. Rapid recharge during post‐drought storm events was shown to lead to a rapid deterioration in microbiological water quality and concentrations above the WHO drinking water guidelines were seen for fluoride, nitrate and lead.
The Occurrence of Fluoride in Malawian Groundwater: Controlling Processes and Health Implications Addison, M. J.¹, Rivett, M. O.¹, Miller, V. M.¹, Phiri, P.², Mleta, P.², Kalin, R. M. The occurrence of fluoride in Malawian groundwater is vastly under‐studied. Almost no attempt has ever been made to trace the geological origins and pathways for fluoride in Malawi. This study collates all existing archive fluoride and fluorosis data for Malawi and re‐analyses it from a geological perspective. What key processes contribute to high levels of fluoride in groundwater and can these areas be risk‐mapped in order to prevent borehole drilling in fluoritic areas? Fluorosis is common and largely undocumented in Malawi so the ability to identify areas with fluoritic groundwater is key to mitigating the negative health implications on the population.
Does Our Healthcare Impact the Aquatic Environment? Pharmaceutical Contamination in the River Thames Debbie White (BGS), Dan Lapworth (BGS), Wayne Civil (Environment Agency), Peter Williams (BGS) Many of the pharmaceuticals that we take for health reasons will end up in the environment. There is a growing interest in the sources, occurrence and environmental impact of pharmaceuticals in the environment. Major sources include waste from manufacturers, excretion from humans or animals and incorrect disposal of unused pharmaceuticals. The large range of compounds in wastewaters, found typically at µg/L concentrations, are difficult and costly to remove through current treatment options leading to discharge to surface waters followed by dilution and dispersion. A recent study of the River Thames from source to sea using the Environment Agency’s LCMS scan showed the widespread occurrence of pharmaceuticals along the whole length of the Thames including at the groundwater-dominated source. Antimicrobials were detected including 3 surface water watch list substances. The presence of AMs within the environment and the potential for build‐up of antimicrobial resistance is of concern for human health.
Chemical Water Quality and Infant Feeding Matt Arnold Malnutrition is a complex medical condition often found in precarious contexts where normal water supply might have been compromised, or there is a reliance on deeper, highly mineralised groundwater. Treatment requires administering precise regimens of electrolyte‐balanced rehydration and specialised milk‐based formulas. However, there are currently no quality guidelines for the water used to reconstitute these products—given the vulnerability of these patients, this is a major gap. Médecins Sans Frontières (MSF) and York University (Toronto) are investigating this issue with the objective of producing WQ guidance for field teams. The extent to which this problem might also affect the wider community and be impacted by climate change, with its obvious consequences on groundwater abstraction, is also being studied.
Managed Aquifer Recharge and Its Impact on Fluoride Contamination in Rajasthan Alison Parker¹, Basant Yadav¹, Kristell le Corre Pidou¹, Pablo Campo Moreno¹, Anupma Sharma², Rakesh Sharma³, Vijay Anand⁴, Deepak Kashyap⁴ This ongoing study focuses on managed aquifer recharge (MAR) structures in Rajasthan, India. In this state, geogenic fluoride is a major challenge so this study is seeking to understand the impact of MAR structures on fluoride contamination of groundwater. The structures could dilute the fluoride, or alternatively the dissolved organic matter in the recharge water could mobilise fluoride. Initial field visits collected samples of groundwater, surface water, soil and rocks at two sites. One was a sand dam, and another was a more complex site featuring ponds of various scales and check dams. This poster will present a preliminary calculation about the maximum fluoride dilution that could be provided by the sand dam.
Baseline Water Quality Monitoring in the Vale of Pickering, North Yorkshire Penny Jenkinson (Envireau Water) Hydraulic fracturing of an existing well at the Kirby Misperton A Wellsite is proposed to enhance the production of natural gas (methane) from the Carboniferous Bowland Shale Formation. Water quality monitoring data has been obtained from the wellsite and surrounding area to provide a baseline against which any changes in chemical and physical attributes can be measured. The list of monitoring parameters is extensive and includes major/minor ions, indicators of fracture fluid additives and dissolved methane. The monitoring data shows clear chemical signatures for waters from different provenances, that potable groundwater is limited to the shallower deposits and that methane is naturally present in the shallow as well as deeper groundwater. The findings concur with the BGS baseline dataset.
Developing Optimised Borehole Heat Exchanger Designs for Deep Geothermal Single Well Systems Sean Watson (John Day Winner), Glasgow University To assess the optimised design of a deep geothermal single well borehole heat exchanger beneath the centre of Glasgow based upon knowledge of the HALO project and local subsurface data in Glasgow. An analysis of the heat output of the well based on the sensitivity of well design, flow rate, temperature and depth shall be conducted. By linking heat output to economic modelling (as in Westaway, 2018), the socio‐economic costs and benefits of the project can be assessed. Scenarios considered may include the provision of heat at the lowest price, extending the borehole to significantly greater depths (e.g., 6 km) to increase the financial viability of the project or instead focusing on maximising carbon emission reductions. If the HALO DGSW development is to be repeated in Scotland, or the rest of the UK, the optimal design and operating properties based upon financial viability and sustainability of the heat resource must be clarified.
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