Catchment Typologies Workshop report, Feb 2017, Edinburgh

This report summarises the discussion and outcomes of a workshop held in Edinburgh in February 2017 to further an area of work on catchment typologies under the Scottish Government’s strategic research programme area on waters. The workshop was organised and facilitated by a project team from the James Hutton Institute and Centre for Ecology & Hydrology. Key stakeholders were invited that represented regulatory and academic interests that are developing and using typology based approaches, and other aspects of spatial data synthesis, for determining grouped behaviours among catchment functions, especially in relation to risks of waterbody responses. The aims of the workshop were to: i) introduce the context of catchment typologies and gain a common understanding; ii) share experiences and establish gaps and opportunities; iii) explore the practicalities of developing typology based approaches; and iv) share next steps in this area of work with key stakeholders. The following synthesis and conclusions result from a set of introductory talks and a two way dialogue with stakeholders. Typologies can be a useful approach to representing grouped behaviours across spatial data relating to catchment functions and waterbody (i.e. receptor) impacts. As such, they can represent commonalities in susceptibilities to multiple interacting stressors. This was thought to be especially useful when combined with risk based approaches that facilitate transfer from data rich to data poor areas or from present to future. There remains a need, however, to communicate the concept of typologies (or our distinct use of them) and terminology such as ‘catchment families’ in a simple way. This may prove useful to non-specialists as a way of conveying grouped behaviours and underlying common ‘ancestry’ within change trajectories. Scaling of typology based approaches to address specific research and operational needs was considered especially important, for input data and outputs, and for different spatial and temporal scales (including, for example, longer-term changes and ‘shocks’ due to extreme events in waterbodies). Satisfying data requirements will constrain the development of typologies and the group acknowledged a role for modelling in filling data gaps, with a need to communicate uncertainty. Good examples of community based approaches to data acquisition, sharing, online and statistical tools were shown from the United States (National Stream Internet project, USDA) and the group recognised that softening institutional barriers and promoting better sharing of data and resources would accelerate the typologies approaches and lead to better outcomes. Finally, specific areas of application of typologies were discussed in relation to a set of case studies. These are detailed in the conclusions to this report

Snow cover, freeze-thaw, and the retention of nutrients in an oceanic mountain ecosystem

Peer reviewe

Dissolved organic carbon dynamics in a UK podzolic moorland catchment: linking storm hydrochemistry, flow path analysis and sorption experiments

Better knowledge of spatial and temporal delivery of dissolved organic carbon (DOC) in small catchments is required to understand the mechanisms behind reported long-term changes in C fluxes from some peatlands. We monitored two storms with contrasting seasons and antecedent conditions in a small upland UK moorland catchment. We examined DOC concentrations and specific UV absorbance (SUVA at 285 nm), together with solute concentrations required to undertake end-member mixing analyses to define dominant flow paths contributing to streamflow. This was combined with laboratory soil-solution equilibrations. We aimed to resolve how seasonal biogeochemical processing of DOC and flowpath changes in organo-mineral soils combine to affect DOC exported via the stream. An August storm following a dry period gave maximum DOC concentration of 10 mg l<sup>−1</sup>. Small DOC:DON ratios (16–28) and SUVA (2.7–3.6 l mg<sup>−1</sup> m<sup>−1</sup>) was attributed to filtration of aromatic compounds associated with up to 53% B horizon flow contributions. This selective filtration of high SUVA DOC was reproduced in the experimental batch equilibration system. For a November storm, wetter antecedent soil conditions led to enhanced soil connectivity with the stream and seven times greater DOC stream-load (maximum concentration 16 mg l<sup>−1</sup>). This storm had a 63% O horizon flow contribution at its peak, limited B horizon buffering and consequently more aromatic DOC (SUVA 3.9–4.5 l mg<sup>−1</sup> m<sup>−1</sup> and DOC:DON ratio 35–43). We suggest that simple mixing of waters from different flow paths cannot alone explain the differences in DOC compositions between August and November and biogeochemical processing of DOC is required to fully explain the observed stream DOC dynamics. This preliminary evidence is in contrast to other studies proposing hydrological controls on the nature of DOC delivered to streams. Although our study is based only on two storms of very different hydrological and biogeochemical periods, this should promote wider study of DOC biogeochemical alteration in headwaters so that this be better incorporated in modelling to predict the impacts of changes in DOC delivery to, and fate in, aquatic systems

Balancing macronutrient stoichiometry to alleviate eutrophication

Reactive nitrogen (N) and phosphorus (P) inputs to surface waters modify aquatic environments and affect public health and recreation. Until now, source control is the dominating measure of eutrophication management, and biological regulation of nutrients is largely neglected, although aquatic microbial organisms have huge potential to process nutrients. The stoichiometric ratio of organic carbon (OC) to N to P atoms should modulate heterotrophic pathways of aquatic nutrient processing, as high OC availability favours aquatic microbial processing. Such microbial processing removes N by denitrification and captures N and P as organically-complexed, less eutrophying forms. With a global data synthesis, we show that the atomic ratios of bioavailable dissolved OC to either N or P in rivers with urban and agricultural land use are often distant from a ‘microbial optimum’. This OC-deficiency relative to high availabilities of N and P likely overwhelms within-river heterotrophic processing and we propose that the capability of streams and rivers to retain N and P may be improved by active stoichiometric rebalancing. This rebalancing should be done by reconnecting appropriate OC sources such as wetlands and riparian forests, many of which have become disconnected from rivers concurrent to the progress of agriculture and urbanization. However, key knowledge gaps leave questions in the safe implementation of this approach in management: Mechanistic research is required to (i) evaluate system responses to catchment inputs of dissolved OC forms and amounts relative to internal-cycling controls of dissolved OC from aquatic production and particulate OC from aquatic and terrestrial sources and (ii) evaluate risk factors in anoxia-mediated P desorption with elevated OC scenarios. Still, we find this to be an approach with high potential for river management and we recommend to evaluate this stoichiometric approach for alleviating eutrophication, improving water quality and aquatic ecosystem health

Control of the conformations of ion Coulomb crystals in a Penning trap

Laser-cooled atomic ions form ordered structures in radiofrequency ion traps and in Penning traps. Here we demonstrate in a Penning trap the creation and manipulation of a wide variety of ion Coulomb crystals formed from small numbers of ions. The configuration can be changed from a linear string, through intermediate geometries, to a planar structure. The transition from a linear string to a zigzag geometry is observed for the first time in a Penning trap. The conformations of the crystals are set by the applied trap potential and the laser parameters, and agree with simulations. These simulations indicate that the rotation frequency of a small crystal is mainly determined by the laser parameters, independent of the number of ions and the axial confinement strength. This system has potential applications for quantum simulation, quantum information processing and tests of fundamental physics models from quantum field theory to cosmology

Annotation of Medieval Music Facsimiles Using ‘Good Enough’ OMR

The Clausula Archive of the Notre Dame Repertory (CANDR) is an in-progress PhD project with the aim of cataloguing, transcribing and analysing digital facsimiles of the thirteenth-century repertory commonly termed Notre Dame polyphony, and a secondary aim of providing new datasets and analytical tools for studying medieval polyphony. This poster highlights the use in the project of (a) a new methodology for de-skewing facsimile images, and (b) average symbol masks in an OMR–enhanced workflow with an emphasis on creating an OMR workflow that is ‘good enough’ to accelerate the annotation of an image dataset of particularly transitional notation

Fluvial transport of suspended sediment and organic carbon during flood events in a large agricultural catchment in southwest France.

Water draining from a large agricultural catchment of 1 110 km2 in southwest France was sampled over an 18-month period to determine the temporal variability in suspended sediment (SS) and dissolved (DOC) and particulate organic carbon (POC) transport during flood events, with quantification of fluxes and controlling factors, and to analyze the relationships between discharge and SS, DOC and POC. A total of 15 flood events were analyzed, providing extensive data on SS, POC and DOC during floods. There was high variability in SS, POC and DOC transport during different seasonal floods, with SS varying by event from 513 to 41 750 t; POC from 12 to 748 t and DOC from 9 to 218 t. Overall, 76 and 62% of total fluxes of POC and DOC occurred within 22% of the study period. POC and DOC export from the Save catchment amounted to 3090 t and 1240 t, equivalent to 1·8 t km−2 y−1 and 0·7 t km−2 y−1, respectively. Statistical analyses showed that total precipitation, flood discharge and total water yield were the major factors controlling SS, POC and DOC transport from the catchment. The relationships between SS, POC and DOC and discharge over temporal flood events resulted in different hysteresis patterns, which were used to deduce dissolved and particulate origins. In both clockwise and anticlockwise hysteresis, POC mainly followed the same patterns as discharge and SS. The DOC-discharge relationship was mainly characterized by alternating clockwise and anticlockwise hysteresis due to dilution effects of water originating from different sources in the whole catchment

The effects of H2SO4 and (NH4)2SO4 treatments on the chemistry of soil drainage water and pine seedlings in forest soil microcosms

International audienceAn experiment comparing effects of sulphuric acid and reduced N deposition on soil water quality and on chemical and physical growth indicators for forest ecosystems is described. Six H2SO4 and (NH4)2SO4 treatment loads, from 0 ? 44 and 0 ? 25 kmolc ha-1 yr-1, respectively, were applied to outdoor microcosms of Pinus sylvestris seedlings in 3 acid to intermediate upland soils (calc-silicate, quartzite and granite) for 2 years. Different soil types responded similarly to H2SO4 loads, resulting in decreased leachate pH, but differently to reduced N inputs. In microcosms of calc-silicate soil, nitrification of NH4 resulted in lower pH and higher cation leaching than in acid treatments. By contrast, in quartzite and granite soils, (NH4)2SO4 promoted direct cation leaching, although leachate pH increased. The results highlighted the importance of soil composition on the nature of the cations leached, the SO4 adsorption capacities and microbial N transformations. Greater seedling growth on calc-silicate soils under both treatment types was related to sustained nutrient availability. Reductions in foliar P and Mg with higher N treatments were observed for seedlings in the calc-silicate soil. There were few treatment effects on quartzite and granite microcosm tree seedlings since P limitation precluded seedling growth responses to treatments. Hence, any benefits of N deposition to seedlings on quartzite and granite soils appeared limited by availability of co-nutrients, exacerbated by rapid depletion of soil exchangeable base cations. Keywords: acidification, manipulation, nitrogen, ammonium, deposition, soil, drainage, pine, microcosms, fores

Determination of the forms and stability of phosphorus in wastewater effluent from a variety of treatment processes

Eutrophication of surface waters is a major issue across the planet, with diffuse (agricultural) and point sources (wastewater treatment works, WwTW) being the main inputs. In the UK WwTW effluent discharges are currently permitted for discharge based on total phosphorus concentration, whereas environmental quality standards (EQS) are set as soluble reactive phosphorus (SRP), which better reflects the bioavailable fraction of phosphorus present in water. This study reports for the first time, concentrations and relative proportions of SRP in effluent from a number of different WwTW employing aluminium and iron dosing for phosphorus removal. In the case of aluminium treatment, SRP constituted only 10 +/- 4% of the 0.75 mg P/l total phosphorus in the effluent. Where iron was dosed SRP comprised 66% +/- 20% of the total phosphorus present where a single dose was applied, which dropped to 26 +/- 17%after a second dose and additional tertiary sand filtration. Phosphorus was determined using two established analytical methods after acid digestion, filtration to 0.45 um (on site and after return to the laboratory and refrigeration for up to 9 days) and settlement. Phosphorus speciation was shown to be stable within all effluents for up to 6 days storage at a temperature of <5 C without the need to filter on site and this was recommended for future effluent monitoring programmes and compliance assessment. Furthermore, because iron and aluminium dosing significantly reduce the SRP proportion in effluents, future monitoring programmes and policy decisions regarding meeting the phosphorus EQS derived as SRP should take this into account