Impacts of nitrate on the water resources of Malta

High density of population (1250 persons/km2) and livestock (300 head/km2). • Heavy dependence on groundwater for public supply and agriculture. • Complex landuse with multiple cropping and small landholdings. • Semi-arid Mediterranean climate with low and variable infiltration (<200 mm/year). • Two aquifers, ‘perched’ and ‘mean sea level’ (MSL) separated by impermeable clay. • Water level in MSL aquifer depressed to 5 m above sea level by abstraction

Review of risk from potential emerging contaminants in UK groundwater

This paper provides a review of the types of emerging organic groundwater contaminants (EGCs) which are beginning to be found in the UK. EGCs are compounds being found in groundwater that were previously not detectable or known to be significant and can come from agricultural, urban and rural point sources. EGCs include nanomaterials, pesticides, pharmaceuticals, industrial compounds, personal care products, fragrances, water treatment by-products, flame retardants and surfactants, as well as caffeine and nicotine. Many are relatively small polar molecules which may not be effectively removed by drinking water treatment. Data from the UK Environment Agency’s groundwater screening programme for organic pollutants found within the 30 most frequently detected compounds a number of EGCs such as pesticide metabolites, caffeine and DEET. Specific determinands frequently detected include pesticides metabolites, pharmaceuticals including carbamazepine and triclosan, nicotine, food additives and alkyl phosphates. This paper discusses the routes by which these compounds enter groundwater, their toxicity and potential risks to drinking water and the environment. It identifies challenges that need to be met to minimise risk to drinking water and ecosystems

Isotope tracing of nitrate : lessons from Malta

Average concentrations of nitrate in Malta’s groundwaters are probably the highest among EU member states. This compromises the quality of an important resource -almost 60% of Malta’s water supply being provided by groundwater. An 15N/14N + 18O/16O isotope study was undertaken as a core part of wide-ranging investigations into the potential sources of the nitrate pollution, its likely future trends, and possible ameliorative actions. The dual isotope (15N/14N + 18O/16O) approach was important for identifying waters affected by denitrification. Excluding these, groundwater from three physically and hydrologically distinct aquifers, with a very wide range in nitrate concentrations (24 to 410 mg NO3 L-1), had remarkably similar isotope compositions: 90% of samples lying within d15N ≈ +8 to +12‰, and d18O ≈ +3 to +6‰. The d18O values are entirely consistent with those expected for microbial nitrification in the presence of surface or groundwaters, and together with 15N values rule out nitrate derivation directly from fertilizers or sewage. In other studies the relatively high d15N values for the waters would probably have been interpreted as indicative of nitrate derived from manure. In Malta, however, cultivated soils have high d15N values, ≈ +6 to +11‰, very similar to the values for nitrate in the groundwater, and argue for a soil-derived source. The implications of a soil-source of such high nitrate levels are discussed, and the study emphasised the importance of characterising the compositions of soils in addition to other sources – a factor often neglected in isotope studies of nitrate

Profiling micro-organic contaminants in groundwater using multi-level piezometers

The presence of micro-organic pollutants, including ‘emerging contaminants’ within groundwater is of increasing interest. Robust protocols are required to minimise the introduction of contamination during the sampling process. Below we discuss the sampling protocols used to reduce inputs of plasticisers during the sampling process, as well as the techniques used to characterise the distribution of micro-organic pollutants in the subsurface. In this study multi-level piezometers installed into the Sherwood Sandstone aquifer in the suburban area of Doncaster, Yorkshire, were used to look at the changes in micropollutants with depth and lithology. Two different methods of pumping groundwaters were employed, and sampling campaigns were undertaken in February and July 2014, under contrasting hydrological conditions

The Nitrate Time Bomb (NTB) Model: a simple but effective method to investigate the impacts of historical nitrate loading on long-term groundwater nitrate concentrations

Nitrate water pollution, which remains an international problem, can cause long-term environmental damage and threaten both the economy and human health. Agricultural land is the major source of nitrate water pollution. It can take decades for nitrate leached from the soil to discharge into freshwaters. However, this nitrate time lag in the groundwater system has generally been ignored within the water resource management in many countries including the UK. We present a nitrate time bomb (NTB) model to modelling nitrate processes in the groundwater system. Whilst NTB contains simplified conceptual models, it can represent the major nitrate and hydrogeological processes in the groundwater system at both national and catchment scales, such as spatio-temporal nitrate loading, low-permeability superficial deposits, dual-porosity unsaturated zones and nitrate dilution in aquifers. The NTB model has been successfully used to simulate annual nitrate concentrations from 1925 to 2150 in the major aquifers in Great Britain and four local aquifer zones in the Eden Catchment, England. Monte Carlo simulations were undertaken to analyse parameter sensitivity and calibrate the model using observed datasets. These results help decision makers to understand how the historical nitrate loading from agricultural land affects the evolution of groundwater quality due to the nitrate time lag in the groundwater system. This NTB approach will be particularly valuable to evaluate the long-term impact and timescale of land management scenarios and programmes of measures introduced to help deliver water quality compliance. This model requires relatively modest parameterisation and is readily transferable to other areas

F-18-FDG and C-11-choline positron emission tomography in human esophago-gastric cancer : prediction of response to therapy

Peer reviewedPublisher PD

Prioritization Approaches for Substances of Emerging Concern in Groundwater:A Critical Review

Risks from emerging contaminants (ECs) in groundwater to human health and aquatic ecology remain difficult to quantify. The number of ECs potentially found in groundwater presents challenges for regulators and water managers regarding selection for monitoring. This study is the first systematic review of prioritization approaches for selecting ECs that may pose a risk in groundwater. Online databases were searched for prioritization approaches relating to ECs in the aquatic environment using standardized key word search combinations. From a total of 672, 33 studies met the eligibility criteria based primarily on the relevance to prioritizing ECs in groundwater. The review revealed the lack of a groundwater specific contaminant prioritization methodology in spite of widely recognized differences between groundwater and surface water environments with regard to pathways to receptors. The findings highlight a lack of adequate evaluation of methodologies for predicting the likelihood of an EC entering groundwater and knowledge gaps regarding the occurrence and fate of ECs in this environment. The review concludes with a proposal for a prioritization framework for ECs in groundwater monitoring that enables priority lists to be updated as new information becomes available for substances with regard to their usage, physicochemical properties, and hazards

Fingerprinting groundwater pollution in catchments with contrasting contaminant sources using microorganic compounds

Evaluating the occurrence of microorganics helps to understand sources and processes which may be controlling the transport and fate of emerging contaminants (ECs). A study was carried out at the contrasting instrumented environmental observatory sites at Oxford, on the peri-urban floodplain gravel aquifer of the River Thames and Boxford, in the rural valley of the River Lambourn on the chalk aquifer, in Southern England to explore the use of ECs to fingerprint contaminant sources and flow pathways in groundwater. At Oxford compounds were typical of a local waste tip plume (not only plasticisers and solvents but also barbiturates and N,N-diethyl-m-toluamide (DEET)) and of the urban area (plasticisers and mood-enhancing drugs such as carbamazepine). At Boxford the results were different with widespread occurrence of agricultural pesticides, their metabolites and the solvent trichloroethene, as well as plasticisers, caffeine, butylated food additives, DEET, parabens and trace polyaromatic hydrocarbons (PAHs). Groups of compounds used in pharmaceuticals and personal care products of different provenance in the environment could be distinguished, i) historical household and medical waste, ii) long-term household usage persistent in groundwater and iii) current usage and contamination from surface water. Co-contaminant and degradation products can also indicate the likely source of contaminants. A cocktail of contaminants can be used as tracers to provide information on catchment pathways and groundwater/surface water interactions. A prominent feature in this study is the attenuation of many EC compounds in the hyporheic zone

Genome-wide association and genome partitioning reveal novel genomic regions underlying variation in gastrointestinal nematode burden in a wild bird

Acknowledgements This study was funded by a BBSRC studentship (MA Wenzel) and NERC grants NE/H00775X/1 and NE/D000602/1 (SB Piertney). The authors are grateful to Fiona Leckie, Andrew MacColl, Jesús Martínez-Padilla, François Mougeot, Steve Redpath, Pablo Vergara† and Lucy M.I. Webster for samples; Keliya Bai, Daisy Brickhill, Edward Graham, Alyson Little, Daniel Mifsud, Lizzie Molyneux and Mario Röder for fieldwork assistance; Gillian Murray-Dickson and Laura Watt for laboratory assistance; Heather Ritchie for helpful comments on manuscript drafts; and all estate owners, factors and keepers for access to field sites, most particularly Stuart Young and Derek Calder (Edinglassie), Simon Blackett, Jim Davidson and Liam Donald (Invercauld and Glas Choille), Richard Cooke and Fred Taylor† (Invermark) and T. Helps (Catterick).Peer reviewedPostprin

A national-scale assessment of micro-organic contaminants in groundwater of England and Wales

A large variety of micro-organic (MO) compounds is used in huge quantities for a range of purposes (e.g. manufacturing, food production, healthcare) and is now being frequently detected in the aquatic environment. Interest in the occurrence of MO contaminants in the terrestrial and aquatic environments continues to grow, as well as in their environmental fate and potential toxicity. However, the contamination of groundwater resources by MOs has a limited evidence base compared to other freshwater resources. Of particular concern are newly ‘emerging contaminants’ such as pharmaceuticals and lifestyle compounds, particularly those with potential endocrine disrupting properties. While groundwater often has a high degree of protection from pollution due to physical, chemical and biological attenuation processes in the subsurface compared to surface aquatic environments, trace concentrations of a large range of compounds are still detected in groundwater and in some cases may persist for decades due to the long residence times of groundwater systems. This study provides the first national-scale assessment of micro-organic compounds in groundwater in England and Wales. A large set of monitoring data was analysed to determine the relative occurrence and detected concentrations of different groups of compounds and to determine relationships with land-use, aquifer type and groundwater vulnerability. MOs detected including emerging compounds such as caffeine, DEET, bisphenol A, anti-microbial agents and pharmaceuticals as well as a range of legacy contaminants including chlorinated solvents and THMs, petroleum hydrocarbons, pesticides and other industrial compounds. There are clear differences in MOs between land-use types, particularly for urban-industrial and natural land-use. Temporal trends of MO occurrence are assessed but establishing long-term trends is not yet possible