There is a growing interest in the occurrence and sources of pharmaceutical substances in the environment. This paper reports the first detailed transect of pharmaceutical occurrence along the River ...Thames, UK, from source to sea, undertaken during a period of high flow in 2016. In 37 samples a total of 41 pharmaceuticals and 2 lifestyle compounds (cocaine and sucralose) were detected. Total concentration of pharmaceuticals ranged from 0.0012 μg/l to 10.24 μg/l with a median of 2.6 μg/l. Sucralose concentrations varied from <0.01 to 5.9 μg/l with a median concentration of 1.93 μg/l and was detected in every sample except the groundwater-dominated sources of the Thames. Antimicrobials, including those on the surface water watch list (erythromycin, clarithromycin and azithromycin) were detected in every site downstream of the Thames source. Diclofenac, recently on the surface water watch list, was detected in 97% of Thames samples and above the proposed EQS of 0.1 μg/l in 12 samples. Distinct increases in concentration and number of pharmaceuticals were found downstream of the Oxford, Mogdon and Hogsmill wastewater treatment works (WWTW) but were more subdued downstream of the Crossness and Beckton WWTW due to the tidal nature of the Thames and combined sewer outflows. Sucralose was found to be an excellent tracer of wastewaters (treated and untreated) and can be used as a proxy for many pharmaceuticals. Paracetamol and ibuprofen were tracers of untreated wastewater inputs to the Thames due to their high biodegradation within WWTWs.
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•Pharmaceutical contamination is linked to WWTW discharge and untreated wastewater.•Sucralose was found to be an excellent proxy for pharmaceutical contamination.•Diclofenac was detected above a proposed EQS of 0.1 μg/l.•Antimicrobials found in every site except the groundwater dominated Thames source.
Emerging organic contaminants (EOCs) are manufactured compounds, used for a range of purposes, that are a rising concern for freshwater quality, human and aquatic health. Their occurrence in ...groundwater has been demonstrated in several international surveys. We conducted the first baseline survey on EOC occurrence in New Zealand groundwater, using a wide-screening approach (723 compounds) and a novel stratified to mean residence time (MRT) randomised design to inform future monitoring. A total of 61 sites were sampled: 51 baseline sites from the State of the Environment (SOE) network in the Waikato region and 10 targeted sites located in the vicinity of known EOC sources for comparison. EOCs were detected at 91% of the baseline sites at concentrations ranging from 0.1 to 11,000 ng·L−1. Multiple groups of EOCs were encountered: pesticides (48 compounds), pharmaceuticals (11), industrial (10), preservatives/food additives (3) and personal care products (1). Similar diversity and concentration range of EOCs were observed at the targeted sites, with the addition of drugs of abuse and life-style compounds. EOC detections occurred across young (1–11 yrs. MRT), intermediate (11–50 yrs. MRT) and old (50–250 yrs. MRT) groundwaters with higher concentrations and more types of EOCs detected at sites in the youngest age category. Concentrations of the 73 compounds detected at baseline sites were comparable to those found in overseas groundwaters with 28 compounds measured at concentrations greater than the EU maximum admissible concentration for pesticides. We used the survey results to: review current pesticide monitoring; propose complementary monitoring; identify potential EOC groundwater tracers and identify compounds for which cost-effective national laboratory capability is needed. The Waikato survey results demonstrated ubiquitous occurrence of unmonitored, unregulated EOCs in groundwater and limitations in using targeted approaches to establish monitoring.
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•New Zealand first emerging organic contaminants in groundwater survey (regional)•Novel EOC screen approach and site selection using groundwater mean residence time•Ubiquitous EOC occurrence with 28 compounds measured above the EU pesticide MAC•Review and recommendations on current monitoring and laboratory capability
There is growing concern globally about the occurrence of anthropogenic organic contaminants in the environment, including pharmaceuticals and personal care products. This concern extends to ...groundwater, which is a critical water resource in Europe, and its protection is a priority to the European Commission, the European Union (EU) Member States and national agencies across Europe. Maintaining good groundwater status supports improved public health, economic growth and sustains groundwater dependant ecosystems. A range of measures have been introduced for regulating several substances that have impacted groundwater (e.g. nitrate and pesticides). However, these measures only cover a small fraction of anthropogenic substances that could pollute groundwater. Monitoring for these unregulated substances is currently very limited or not carried out at all. Therefore, a coordinated European-wide approach is needed to identify, monitor and characterise priority substances or groups of substances that have the potential to pollute groundwater. This evidence base is critical for policy development and controls on these currently unregulated substances. The European Commission highlighted this as a need during the review of the EU Groundwater Directive Annexes in 2014, when the requirement to develop a Groundwater Watch List (GWWL) was established. This paper describes the approach that has been developed through a voluntary initiative as part of the EU CIS Working Group Groundwater to establish the voluntary EU GWWL. The process for developing the GWWL is one that has brought together researchers, regulators and industry, and is described here for the first time. A summary of the key principles behind the methodology is presented as well as results from pilot studies using per- and polyfluoroalkyl substances and pharmaceuticals. These explore and support the viability of the GWWL process, an important step towards its adoption and its future use for groundwater protection across Europe.
•North Sea fluorescent DOM field sampled to map terrestrial inputs and distributions.•DOM pool characterised via absorbance and excitation-emission fluorescent spectra.•Three distinct FDOM ...fluorophores identified.•No clear evidence found for significant terrestrial DOM export to the Atlantic Ocean.•North Sea terrestrial DOM distributions appear stable over multi-decadal timescales.
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The flow of terrestrial carbon to rivers and inland waters is a major term in the global carbon cycle. The organic fraction of this flux may be buried, remineralized or ultimately stored in the deep ocean. The latter can only occur if terrestrial organic carbon can pass through the coastal and estuarine filter, a process of unknown efficiency. Here, data are presented on the spatial distribution of terrestrial fluorescent and chromophoric dissolved organic matter (FDOM and CDOM, respectively) throughout the North Sea, which receives organic matter from multiple distinct sources. We use FDOM and CDOM as proxies for terrestrial dissolved organic matter (tDOM) to test the hypothesis that tDOM is quantitatively transferred through the North Sea to the open North Atlantic Ocean. Excitation emission matrix fluorescence and parallel factor analysis (EEM-PARAFAC) revealed a single terrestrial humic-like class of compounds whose distribution was restricted to the coastal margins and, via an inverse salinity relationship, to major riverine inputs. Two distinct sources of fluorescent humic-like material were observed associated with the combined outflows of the Rhine, Weser and Elbe rivers in the south-eastern North Sea and the Baltic Sea outflow to the eastern central North Sea. The flux of tDOM from the North Sea to the Atlantic Ocean appears insignificant, although tDOM export may occur through Norwegian coastal waters unsampled in our study. Our analysis suggests that the bulk of tDOM exported from the Northwest European and Scandinavian landmasses is buried or remineralized internally, with potential losses to the atmosphere. This interpretation implies that the residence time in estuarine and coastal systems exerts an important control over the fate of tDOM and needs to be considered when evaluating the role of terrestrial carbon losses in the global carbon cycle.
Microbial water quality is frequently assessed with a risk indicator approach that relies on Escherichia coli. Relying exclusively on E. coli is limiting, particularly in low-resource settings, and ...we argue that risk assessments could be improved by a complementary parameter, tryptophan-like fluorescence (TLF). Over two campaigns (June 2016 and March 2017) we sampled 37 water points in rural Kwale County, Kenya for TLF, E. coli and thermotolerant coliforms (total n = 1082). Using three World Health Organization defined classes (very high, high, and low/intermediate), risk indicated by TLF was not significantly different from risk indicated by E. coli (p = 0.85). However, the TLF and E. coli risk classifications did show disagreement, with TLF indicating higher risk for 14% of samples and lower risk for 13% of samples. Comparisons of duplicate/replicate results demonstrated that precision is higher for TLF (average relative percent difference of duplicates = 14%) compared to culture-based methods (average RPD of duplicates ≥ 26%). Additionally, TLF sampling is more practical because it requires less time and resources. Precision and practicality make TLF well-suited to high-frequency sampling in low resource contexts. Interpretation and interference challenges are minimised when TLF is measured in groundwaters, which typically have low dissolved organic carbon, relatively consistent temperature, negligible turbidity and pH between 5 and 8. TLF cannot be used as a proxy for E. coli on an individual sample basis, but it can add value to groundwater risk assessments by improving prioritization of sampling and by increasing understanding of spatiotemporal variability.
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•Tryptophan-like fluorescence (TLF) can complement E. coli as a risk indicator.•Both TLF and E. coli distinguish low/intermediate, high and very high risk sources.•TLF has negligible method-induced variability, unlike bacteriological analyses.•TLF is useful for pre-screening, monitoring and demonstrating risk in groundwater.
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.
•Organic contaminants were measured at two contrasting groundwater study sites.•Cocktails of compounds make good tracers of water type.•Plasticisers, solvents, DEET and drugs were found at a peri-urban site.•Pesticides, solvents, caffeine, parabens and food additives were found at a rural site.
Eutrophication is a globally significant challenge facing aquatic ecosystems, associated with human induced enrichment of these ecosystems with nitrogen (N) and phosphorus (P). However, the limited ...availability of inherent labels for P and N has constrained understanding of the triggers for eutrophication in natural ecosystems and appropriate targeting of management responses. This paper proposes and evaluates a new multi-stable isotope framework that offers inherent labels to track biogeochemical reactions governing both P and N in natural ecosystems. The framework couples highly novel analysis of the oxygen isotope composition of phosphate (δ18OPO4) with dual isotope analysis of oxygen and N within nitrate (δ15NNO3, δ18ONO3) and with stable N isotope analysis in ammonium (δ15NNH4). The River Beult in England is used as an exemplar system for initial evaluation of this framework. Our data demonstrate the potential to use stable isotope labels to track the input and downstream fate of nutrients from point sources, on the basis of isotopic differentiation for both P and N between river water and waste water treatment work effluent (mean difference = +1.7‰ for δ18OPO4; +15.5‰ for δ15NNH4 (under high flow); +7.3‰ for δ18ONO3 and +4.4‰ for δ15NNO3). Stable isotope data reveal nutrient inputs to the river upstream of the waste water treatment works that are consistent with partially denitrified sewage or livestock sources of nitrate (δ15NNO3 range = +11.5 to +13.1‰) and with agricultural sources of phosphate (δ18OPO4 range = +16.6 to +19.0‰). The importance of abiotic and metabolic processes for the in-river fate of N and P are also explored through the stable isotope framework. Microbial uptake of ammonium to meet metabolic demand for N is suggested by substantial enrichment of δ15NNH4 (by 10.2‰ over a 100 m reach) under summer low flow conditions. Whilst the concentration of both nitrate and phosphate decreased substantially along the same reach, the stable isotope composition of these ions did not vary significantly, indicating that concentration changes are likely driven by abiotic processes of dilution or sorption. The in-river stable isotope composition and the concentration of P and N were also largely constant downstream of the waste water treatment works, indicating that effluent-derived nutrients were not strongly coupled to metabolism along this in-river transect. Combined with in-situ and laboratory hydrochemical data, we believe that a multi-stable isotope framework represents a powerful approach for understanding and managing eutrophication in natural aquatic ecosystems.
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•First combined application of nitrogen and phosphate oxygen isotopes.•Isotopic differentiation for both P and N between river and effluent water.•Partially denitrified agricultural sources of nitrate identified.•Isotopes showed effluent-derived nutrients not strongly coupled to metabolism.•Powerful new approach for understanding and responding to eutrophication.
The dissolved organic carbon (DOC) export from land to ocean via rivers is a significant term in the global C cycle, and has been modified in many areas by human activity. DOC exports from large ...global rivers are fairly well quantified, but those from smaller river systems, including those draining oceanic regions, are generally under-represented in global syntheses. Given that these regions typically have high runoff and high peat cover, they may exert a disproportionate influence on the global land–ocean DOC export. Here we describe a comprehensive new assessment of the annual riverine DOC export to estuaries across the island of Great Britain (GB), which spans the latitude range 50–60° N with strong spatial gradients of topography, soils, rainfall, land use and population density. DOC yields (export per unit area) were positively related to and best predicted by rainfall, peat extent and forest cover, but relatively insensitive to population density or agricultural development. Based on an empirical relationship with land use and rainfall we estimate that the DOC export from the GB land area to the freshwater-seawater interface was 1.15 Tg C year
−1
in 2017. The average yield for GB rivers is 5.04 g C m
−2
year
−1
, higher than most of the world’s major rivers, including those of the humid tropics and Arctic, supporting the conclusion that under-representation of smaller river systems draining peat-rich areas could lead to under-estimation of the global land–ocean DOC export. The main anthropogenic factor influencing the spatial distribution of GB DOC exports appears to be upland conifer plantation forestry, which is estimated to have raised the overall DOC export by 0.168 Tg C year
−1
. This is equivalent to 15% of the estimated current rate of net CO
2
uptake by British forests. With the UK and many other countries seeking to expand plantation forest cover for climate change mitigation, this ‘leak in the ecosystem’ should be incorporated in future assessments of the CO
2
sequestration potential of forest planting strategies.
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•First regional investigation of EOCs in Dinaric karst aquifers.•65 different EOCs detected, conc. <1 ng/L for almost half.•EOC concentrations are two orders of magnitude lower than ...in other groundwater types.•EOCs are detected more frequently than in other types of groundwater.•EOCs are detected in greater or comparable numbers than in other groundwater types.
Emerging organic contaminants (EOCs) have become of increasing interest due to concerns about their impact on humans and the wider environment. Karst aquifers are globally widespread, providing critical water supplies and sustaining rivers and ecosystems, and are particularly susceptible to pollution. However, EOC distributions in karst remain quite poorly understood. This study looks at the occurrence of EOCs in the Croatian karst, which is an example of the “classical” karst, a highly developed type of karst that occurs throughout the Dinaric region of Europe. Samples were collected from 17 karst springs and one karst lake used for water supply in Croatia during two sampling campaigns. From a screen of 740 compounds, a total of 65 compounds were detected. EOC compounds from the pharmaceutical (n = 26) and agrochemical groups (n = 26) were the most frequently detected, while industrials and artificial sweeteners had the highest concentrations (range 8–440 ng/L). The number of detected compounds and the frequency of detection demonstrate the vulnerability of karst to EOC pollution. Concentrations of 5 compounds (acesulfame, sucralose, perfluorobutane sulfonate, emamectin B1b, and triphenyl phosphate) exceeded EU standards and occurred at concentrations that are likely to be harmful to ecosystems. Overall, most detections were at low concentrations (50 % <1 ng/L). This may be due to high dilution within the exceptionally large springs of the Classical karst, or due to relatively few pollution sources within the catchments. Nevertheless, EOC fluxes are considerable (10 to 106 ng/s) due to the high discharge of the springs. Temporal differences were observed, but without a clear pattern, reflecting the highly variable nature of karst springs that occurs over both seasonal and short-term timescales. This research is one of a handful of regional EOC investigations in karst groundwater, and the first regional study in the Dinaric karst. It demonstrates the need for more frequent and extensive sampling of EOCs in karst to protect human health and the environment.
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