Nitrate concentrations and fluxes in the River Thames over 140 years (1868–2008): are increases irreversible?

Howden, Nicholas J K; Burt, T. P.; Worrall, Fred; Whelan, M. J.; Bieroza, Magdalena

doi:10.1002/hyp.7835

Cited by 151 publications

(149 citation statements)

References 34 publications

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“…A net impact of increased N loading to groundwater [Puckett et al, 2011] and surface water [Howden et al, 2010] is the eutrophication of coastal waters [Scavia et al, 2006;Turner et al, 2006;Mulholland and Webster, 2010;Testa et al, 2014]. For example, the delivery of N-along with phosphorus and sedimenthas resulted in significant seasonal hypoxia in the Chesapeake Bay, which in turn has resulted in considerable investments into restoration activities.…”

Section: Introductionmentioning

confidence: 99%

Quantifying watershed‐scale groundwater loading and in‐stream fate of nitrate using high‐frequency water quality data

Miller

Tesoriero

Capel

et al. 2016

Water Resources Research

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We describe a new approach that couples hydrograph separation with high-frequency nitrate data to quantify time-variable groundwater and runoff loading of nitrate to streams, and the net in-stream fate of nitrate at the watershed scale. The approach was applied at three sites spanning gradients in watershed size and land use in the Chesapeake Bay watershed. Results indicate that 58-73% of the annual nitrate load to the streams was groundwater-discharged nitrate. Average annual first-order nitrate loss rate constants (k) were similar to those reported in both modeling and in-stream process-based studies, and were greater at the small streams (0.06 and 0.22 day 21 ) than at the large river (0.05 day 21 ), but 11% of the annual loads were retained/lost in the small streams, compared with 23% in the large river. Larger streambed area to water volume ratios in small streams results in greater loss rates, but shorter residence times in small streams result in a smaller fraction of nitrate loads being removed than in larger streams. A seasonal evaluation of k values suggests that nitrate was retained/lost at varying rates during the growing season. Consistent with previous studies, streamflow and nitrate concentrations were inversely related to k. This new approach for interpreting high-frequency nitrate data and the associated findings furthers our ability to understand, predict, and mitigate nitrate impacts on streams and receiving waters by providing insights into temporal nitrate dynamics that would be difficult to obtain using traditional field-based studies.

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Section: Introductionmentioning

confidence: 99%

Quantifying watershed‐scale groundwater loading and in‐stream fate of nitrate using high‐frequency water quality data

Miller

Tesoriero

Capel

et al. 2016

Water Resources Research

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“…The regulation of nutrient inputs in waters through the elimination of N and P during wastewater treatment, better agricultural practices and restriction of the use of phosphorus products (EEC, 1991a and b) led to a decrease in phosphate and/or nitrate content which has been recorded in several European rivers presenting temperate and continental regimes since the mid-1990s, including the Elbe (Lehmann and Rode, 2001), the Seine , the Thames (Howden et al, 2010), the Danube (Istvánovics and Honti, 2012), the Rhine (Hartmann et al, 2007) as well as some Mediterranean (Ludwig et al, 2009) and Scandinavian rivers (Grimvall et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, phytoplanktonic biomass remains at a high level in many water bodies, evidencing that the leaching of long-stored nutrient in soils is still significant: if nutrient mobility should increase with global warming because of the acceleration of organic matter mineralization and of higher soil leaching (Bouraoui et al, 2002;Arheimer et al, 2005), the river system response time to a nitrogen input reduction will be limited by the time required for nitrate to be released from soil to receiving waters (Jackson et al, 2008;Bouraoui and Grizzetti, 2011). Therefore, we should expect that changes in current agricultural practices may improve water quality only after several decades (Behrendt et al, 2002;Howden et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Eutrophication mitigation in rivers: 30 years of trends in spatial and seasonal patterns of biogeochemistry of the Loire River (1980–2012)

et al. 2015

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Abstract. Trends and seasonality analysis from 1980 onward and longitudinal distribution, from headwaters to estuary, of chlorophyll a, nitrate and phosphate were investigated in the eutrophic Loire River. The continuous decline of phosphate concentrations which has been recorded since 1991 both in the main river and in the tributaries has led to the conclusion that it was responsible for the significant reduction in phytoplanktonic biomass across the whole river system, although Corbicula spp. clams invaded the river during the same period and probably played a significant role in the phytoplankton decline. While eutrophication remained lower in the main tributaries than in the Loire itself, they were found to contribute up to ≈ 35 % to the total nutrient load of the main river. The seasonality analysis revealed significant seasonal variations for the different eutrophication metrics and calls into question the classical monthly survey recommended by national or international authorities. Reducing P inputs impacted these seasonal variations: the decline of seasonal amplitudes of chlorophyll a reduced the seasonal amplitude of orthophosphate and of daily variations of dissolved oxygen and pH but did not significantly affect the seasonal amplitude of nitrate. Thus, the influence of phytoplankton on seasonal variations of nitrate was minor throughout the period of study.

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“…It has been difficult to see a major impact of this strategy in the UK (Burt et al, 2011;Howden et al, 2010), although there are signs that reductions are beginning to have an impacts (Howden et al, 2010). However, in Denmark, since 1985, seven National Action Plans have been implemented to reduce the N discharge from point sources and N losses from agriculture (Kronvang et al, 2008).…”

Section: Mitigation -An Enhanced Nvz Strategy For the Hampshire Avonmentioning

confidence: 99%

“…There has also been a drive to reduce N fertilizer additions by creating nitrate vulnerable zones (NVZ) and restricting N application rates onto arable crops and improved grassland. In groundwater-fed rivers of the UK there is, as yet, little evidence to suggest that nitrate concentrations have reduced significantly in response to restricted fertilizer application (Burt et al, 2011;Howden et al, 2010). In Denmark, however, N addition rates have been significantly reduced and there are long term reductions in DIN in groundwaters and rivers (Hansen et al, 2011;Kronvang et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Modelling flow and inorganic nitrogen dynamics on the Hampshire Avon: Linking upstream processes to downstream water quality

Jin

Whitehead

Heppell

et al. 2016

Science of The Total Environment

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Managing diffuse pollution in catchments is a major issue for environmental managers planning to meet water quality standards and comply with the EU Water Framework Directive. A major source of diffuse pollution is from nitrogen, with high nitrate concentrations affecting water supplies and in-stream ecology. A dynamic, process based model of flow, nitrate and ammonium (INCA-N) has been applied to the Hampshire Avon as part of the NERC Macronutrient Cycles Programme to link upstream and downstream measurements of water chemistry. The model has been calibrated and validated against Environment Agency discharge and solute chemistry data, as well as a data set collected from a river site immediately upstream of the estuary tidal limit. Upstream measurements of denitrification at six sites have been used to evaluate nitrate removal rates in vegetated and non-vegetated conditions. Results show that sediments underlying vegetation were associated with significantly higher rates of nitrate removal than un-vegetated sediments (with an average increase of 245%). These data have been used to scale up rates of nitrate loss to the whole catchment scale and have been implemented via the model. The effects of streambed geology and macrophyte cover on catchment-scale nitrogen dynamics are explored and nutrient fluxes entering the estuary are evaluated. The model is used to test a strategy for nitrogen reduction assessed using a nitrate vulnerable zone (NVZ) methodology. It suggests that nitrate and ammonium concentrations could be reduced by 10% in 10 years and much lower nitrogen level can be achieved but only over a long time period.

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Nitrate concentrations and fluxes in the River Thames over 140 years (1868–2008): are increases irreversible?

Cited by 151 publications

References 34 publications

Quantifying watershed‐scale groundwater loading and in‐stream fate of nitrate using high‐frequency water quality data

Quantifying watershed‐scale groundwater loading and in‐stream fate of nitrate using high‐frequency water quality data

Eutrophication mitigation in rivers: 30 years of trends in spatial and seasonal patterns of biogeochemistry of the Loire River (1980–2012)

Modelling flow and inorganic nitrogen dynamics on the Hampshire Avon: Linking upstream processes to downstream water quality

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