Phosphorus losses from land to water will be impacted by climate change and land management for food production, with detrimental impacts on aquatic ecosystems. Here we use a unique combination of ...methods to evaluate the impact of projected climate change on future phosphorus transfers, and to assess what scale of agricultural change would be needed to mitigate these transfers. We combine novel high-frequency phosphorus flux data from three representative catchments across the UK, a new high-spatial resolution climate model, uncertainty estimates from an ensemble of future climate simulations, two phosphorus transfer models of contrasting complexity and a simplified representation of the potential intensification of agriculture based on expert elicitation from land managers. We show that the effect of climate change on average winter phosphorus loads (predicted increase up to 30% by 2050s) will be limited only by large-scale agricultural changes (e.g., 20-80% reduction in phosphorus inputs).The impact of climate change on phosphorus (P) loss from land to water is unclear. Here, the authors use P flux data, climate simulations and P transfer models to show that only large scale agricultural change will limit the effect of climate change on average winter P loads in three catchments across the UK.
We hypothesise that climate change, together with intensive agricultural systems, will increase the transfer of pollutants from land to water and impact on stream health. This study builds, for the ...first time, an integrated assessment of nutrient transfers, bringing together a) high-frequency data from the outlets of two surface water-dominated, headwater (~10km2) agricultural catchments, b) event-by-event analysis of nutrient transfers, c) concentration duration curves for comparison with EU Water Framework Directive water quality targets, d) event analysis of location-specific, sub-daily rainfall projections (UKCP, 2009), and e) a linear model relating storm rainfall to phosphorus load. These components, in combination, bring innovation and new insight into the estimation of future phosphorus transfers, which was not available from individual components. The data demonstrated two features of particular concern for climate change impacts. Firstly, the bulk of the suspended sediment and total phosphorus (TP) load (greater than 90% and 80% respectively) was transferred during the highest discharge events. The linear model of rainfall-driven TP transfers estimated that, with the projected increase in winter rainfall (+8% to +17% in the catchments by 2050s), annual event loads might increase by around 9% on average, if agricultural practices remain unchanged. Secondly, events following dry periods of several weeks, particularly in summer, were responsible for high concentrations of phosphorus, but relatively low loads. The high concentrations, associated with low flow, could become more frequent or last longer in the future, with a corresponding increase in the length of time that threshold concentrations (e.g. for water quality status) are exceeded. The results suggest that in order to build resilience in stream health and help mitigate potential increases in diffuse agricultural water pollution due to climate change, land management practices should target controllable risk factors, such as soil nutrient status, soil condition and crop cover.
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•Climate change may increase pollutant transfers from agricultural land.•High temporal resolution data enabled present day nutrient dynamics to be analysed.•High flow events (>Q10) transported >90% of sediment, >80% of phosphorus•Longer periods of low flow and high concentration will increase ecological risk.•Average phosphorus loads may increase by 9% with higher rainfall volume and intensity.
Background The dynamics of phosphorus (P) in the environment is important for regulating nutrient cycles in natural and managed ecosystems and an integral part in assessing biological resilience ...against environmental change. Organic P (Po) compounds play key roles in biological and ecosystems function in the terrestrial environment being critical to cell function, growth and reproduction. Scope We asked a group of experts to consider the global issues associated with Po in the terrestrial environment, methodological strengths and weaknesses, benefits to be gained from understanding the Po cycle, and to set priorities for Po research. Conclusions We identified seven key opportunities for Po research including: the need for integrated, quality controlled and functionally based methodologies; assessment of stoichiometry with other elements in organic matter; understanding the dynamics of Po in natural and managed systems; the role of microorganisms in controlling Po cycles; the implications of nanoparticles in the environment and the need for better modelling and communication of the research. Each priority is discussed and a statement of intent for the Po research community is made that highlights there are key contributions to be made toward understanding biogeochemical cycles, dynamics and function of natural ecosystems and the management of agricultural systems.
Inositol phosphates in the environment Turner, Benjamin L.; Papházy, Michael J.; Haygarth, Philip M. ...
Philosophical transactions of the Royal Society of London. Series B. Biological sciences,
04/2002, Volume:
357, Issue:
1420
Journal Article
Peer reviewed
Open access
The inositol phosphates are a group of organic phosphorus compounds found widely in the natural environment, but that represent the greatest gap in our understanding of the global phosphorus cycle. ...They exist as inositols in various states of phosphorylation (bound to between one and six phosphate groups) and isomeric forms (e.g. myo, D-chiro, scyllo, neo), although myo-inositol hexakisphosphate is by far the most prevalent form in nature. In terrestrial environments, inositol phosphates are principally derived from plants and accumulate in soils to become the dominant class of organic phosphorus compounds. Inositol phosphates are also present in large amounts in aquatic environments, where they may contribute to eutrophication. Despite the prevalence of inositol phosphates in the environment, their cycling, mobility and bioavailability are poorly understood. This is largely related to analytical difficulties associated with the extraction, separation and detection of inositol phosphates in environmental samples. This review summarizes the current knowledge of inositol phosphates in the environment and the analytical techniques currently available for their detection in environmental samples. Recent advances in technology, such as the development of suitable chromatographic and capillary electrophoresis separation techniques, should help to elucidate some of the more pertinent questions regarding inositol phosphates in the natural environment.
This paper uses high-frequency bankside measurements from three catchments selected as part of the UK government-funded Demonstration Test Catchments (DTC) project. We compare the hydrological and ...hydrochemical patterns during the water year 2011-2012 from the Wylye tributary of the River Avon with mixed land use, the Blackwater tributary of the River Wensum with arable land use and the Newby Beck tributary of the River Eden with grassland land use. The beginning of the hydrological year was unusually dry and all three catchments were in states of drought. A sudden change to a wet summer occurred in April 2012 when a heavy rainfall event affected all three catchments. The year-long time series and the individual storm responses captured by in situ nutrient measurements of nitrate and phosphorus (total phosphorus and total reactive phosphorus) concentrations at each site reveal different pollutant sources and pathways operating in each catchment. Large storm-induced nutrient transfers of nitrogen and or phosphorus to each stream were recorded at all three sites during the late April rainfall event. Hysteresis loops suggested transport-limited delivery of nitrate in the Blackwater and of total phosphorus in the Wylye and Newby Beck, which was thought to be exacerbated by the dry antecedent conditions prior to the storm. The high rate of nutrient transport in each system highlights the scale of the challenges faced by environmental managers when designing mitigation measures to reduce the flux of nutrients to rivers from diffuse agricultural sources. It also highlights the scale of the challenge in adapting to future extreme weather events under a changing climate.
This chapter provides a comprehensive review of the literature relating to the impacts of grazing animals on the quality of soils, vegetation, and surface waters. It focuses on intensively managed ...grasslands where there is the greatest potential for these impacts to be observed. The chapter indicates that while well-managed grazing can be beneficial to the environment, intensively managed grazing can actually lead to the degradation of both the soil and vegetation of grassland environments. The various causes, forms, and consequences of this degradation are discussed in detail, and gaps in the knowledge are identified. The chapter highlights the need for recognition and quantification of the relationships between the on-site impacts of grazing animals (i.e., changes in soil properties and vegetation cover) and the off-site impacts of grazing animals (i.e., the impact of these changes on hydrology and water quality in surface waters), as these relationships have, in the past, only been alluded to by authors. However, there exists relatively little research evidence to support and quantify these relationships, thus herein we describe data required to address the lack of understanding of the role of grazing animals on grasslands. Finally, the last section of this chapter considers the land management and remediation options available for the reduction of the impacts of intensive livestock farming.
Diffuse pollution from agriculture constitutes a key pressure on the water quality of freshwaters and is frequently the cause of ecological degradation. The problem of diffuse pollution can be ...conceptualised with a source-mobilisation-pathway (or delivery)-impact model, whereby the combination of high source risk and strong connected pathways leads to ‘critical source areas’ (CSAs). These areas are where most diffuse pollution will originate, and hence are the optimal places to implement mitigation measures. However, identifying the locations of these areas is a key problem across different spatial scales within catchments. A number of approaches are frequently used for this assessment, although comparisons of these assessments are rarely carried out. We evaluate the CSAs identified via traditional walkover surveys supported by three different approaches, highlighting their benefits and disadvantages. These include a custom designed smartphone app; a desktop geographic information system (GIS) and terrain analysis-based SCIMAP (Sensitive Catchment Integrated Modelling and Analysis Platform) approach; and the use of a high spatial resolution drone dataset as an improved input data for SCIMAP modelling. Each of these methods captures the locations of the CSAs, revealing similarities and differences in the prioritisation of CSA features. The differences are due to the temporal and spatial resolution of the three methods such as the use of static land cover information, the ability to capture small scale features, such as gateways and the incomplete catchment coverage of the walkover survey. The relative costs and output resolutions of the three methods indicate that they are suitable for application at different catchment scales in conjunction with other methods. Based on the results in this paper, it is recommended that a multi-evidence-based approach to diffuse pollution management is taken across catchment spatial scales, incorporating local knowledge from the walkover with the different data resolutions of the SCIMAP approach.
•Comparison of data capture methods for diffuse pollution (DP) identification.•Walkover app, drone images and desktop study identify priorities for DP mitigation.•Differences in spatio-temporal resolution highlight method benefits and trade-offs.•Suggests multi-evidence approach for catchments using app walkover and SCIMAP model.
This critical review introduces a template that links phosphorus (P) sources and mobilisation processes to the delivery of P to receiving waters where deleterious impact is of concern. It therefore ...serves as a key introductory paper in this special issue. The entire process is described in terms of a ‘P transfer continuum’ to emphasise the interdisciplinary and inter-scale nature of the problem. Most knowledge to date is derived from mechanistic studies on the sources and mobilisation of P using controlled experiments that have formed the basis for mitigation strategies aimed at minimising transfer from agricultural fields. However, our ability to extrapolate this information to larger scales is limited by a poor knowledge base while new conceptual advances in the areas of complex systems and fractal dynamics indicate the limitations of past theoretical frameworks. This is compounded by the conceptual and physical separation of scientists working at different scales within the terrestrial and aquatic sciences. Multi-scaled approaches are urgently required to integrate different disciplines and provide a platform to develop mechanistic modelling frameworks, collect new data and identify critical research questions.
Whilst a large body of plot and field-scale research exists on the sources, behaviour and mitigation of diffuse water pollution from agriculture, putting this evidence into a practical, context at ...large spatial scales to inform policy remains challenging. Understanding the behaviour of pollutants (nutrients, sediment, microbes and pesticides) and the effectiveness of mitigation strategies over whole catchments and long timeframes requires new, interdisciplinary approaches to organise and undertake research. This paper provides an introduction to the demonstration test catchments (DTC) programme, which was established in 2009 to gather empirical evidence on the cost-effectiveness of combinations of diffuse pollution mitigation measures at catchment scales. DTC firstly provides a physical platform of instrumented study catchments in which approaches for the mitigation of diffuse agricultural water pollution can be experimentally tested and iteratively improved. Secondly, it has established national and local knowledge exchange networks between researchers and stakeholders through which research has been co-designed. These have provided a vehicle to disseminate emerging findings to inform policy and land management practice. The role of DTC is that of an outdoor laboratory to develop knowledge and approaches that can be applied in less well studied locations. The
research platform
approach developed through DTC has brought together disparate research groups from different disciplines and institutions through nationally coordinated activities. It offers a model that can be adopted to organise research on other complex, interdisciplinary problems to inform policy and operational decision-making.
This paper describes a research platform approach that has been developed in England to bring together researchers and stakeholders from a wide range of institutions to undertake multi-disciplinary, catchment-scale research on approaches to tackle agricultural water pollution.
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