Instream wood increases riverbed temperature variability in a lowland sandy stream

The (re)introduction of wood into rivers is becoming increasingly popular in river restoration and natural flood management schemes. While instream wood is known to promote geomorphic and hydraulic diversity, the impact of wood in driving surface water‐streambed exchange and subsequent streambed temperatures remains under‐researched, particularly in lowland rivers. We make use of the occurrence of three naturally occurring wood structures in a small, lowland sandy stream to determine how the presence of wood alters the geomorphic, hydraulic and thermal properties of the streambed. Our results show that instream wood plays an important role in promoting localized geomorphic complexity and thermal variation in the streambed. Locations within and immediately downstream of wood structures displayed the highest temperature range and daily variation. Locations upstream of wood structures were characterized by weaker daily temperature variation, while areas without wood displayed relatively stable streambed temperatures, with little diurnal fluctuation. Our study indicates that at this lowland site, instream wood increased seasonal temperature extremes (increased summer and decreased winter temperatures) at shallow depths by enhancing infiltration of warmer (summer) and colder (winter) surface water. This reduction in thermal buffering is likely to have significant implications to streambed‐dwelling communities and highlights that the thermal impacts of wood reintroduction in lowland rivers should be considered prior to river restoration

Repeated high flows drive morphological change in rivers in recently deglaciated catchments

Climate change is decreasing glacier cover and increasing the frequency and magnitude of precipitation-driven high flows and floods in many regions of the world. Precipitation may become the dominant water source for river systems in recently deglaciated catchments, with major rainfall events driving significant changes in river channel morphology. Few studies, however, have examined river channel response to repeated precipitation-driven high flows. In this study, we measured the geomorphological condition of four low-order rivers in recently deglaciated catchments (70–210 years ice free) before and after a series of repeated precipitation-driven high flows during summer 2014. High flows drove substantial initial morphological change, with up to 75% change in baseflow channel planform position and active channel form change from pre- to post-high flow. Post-high flow years were associated with increased instream wood and geomorphological complexity at all but the youngest river. Channel changes were part of an active relaxation stage at all rivers, where channels continued to migrate, and complexity varied through time. Overall, these measurements permit us to propose a conceptual model of the role of geomorphologically effective high flows in the context of paraglacial adjustment theory. Specifically, we suggest that older rivers in recently deglaciated catchments can undergo a short-term (&lt;10 years) increase in the rate of geomorphological development as a result of the recruitment of instream wood and channel migration during and following repeated precipitation-driven high flows. Enhancing our knowledge of these geomorphological and paraglacial processes in response to high flows is important for the effective management of riverine water and ecosystem resources in rapidly changing environments.</p

О взаимодействии карбазолилтиирана с карбоновыми кислотами

Изучено взаимодействие карбазолилтиирана с карбоновыми (уксусной, акриловой, метакриловой) и дикарбоновыми (адипиновой, себациновой, фталевой) кислотами. Показано, что основными продуктами взаимодействия являются олигомеры. С избытком уксусной кислоты, наряду с олигомером, выделен также продукт присоединения уксусной кислоты к карбазолилтиирану, идентифицированный как 2-меркапто-3-(9`-карбазолил)-1-ацетокси-пропан. Найдены условия получения всех олигомерных продуктов, изучены их свойства, показаны возможности применения

A river classification scheme to assess macroinvertebrate sensitivity to water abstraction pressures

The concept of environmental flows has been developed to manage human alteration of river flow regimes, as effective management requires an understanding of the ecological consequences of flow alteration. This study explores the concept of macroinvertebrate sensitivity to river flow alteration to establish robust quantitative relationships between biological indicators and hydrological pressures. Existing environmental flow classifications used by the environmental regulator for English rivers were tested using multilevel regression modelling. Results showed a weak relationship between the current abstraction sensitivity classification and macroinvertebrate response to flow pressure. An alternative approach, based on physically‐derived river types, was a better predictor of macroinvertebrate response. Intermediate sized lowland streams displayed the best model fit, while upland rivers exhibited poor model performance. A better understanding of the ecological response to flow variation in different river types could help water resource managers develop improved ecologically appropriate flow regimes, which support the integrity of river ecosystems

The influence of land management and seasonal changes in surface vegetation on flood mitigation in two UK upland catchments

As the frequency and magnitude of storm events increase with climate change, understanding how season and management influence flood peaks is essential. The influence of season and management of grasslands on flood peak timing and magnitude was modelled for Swindale and Calderdale, two catchments in northern England. Spatially-Distributed TOPMODEL was used to investigate two scenarios across four storm events using empirically-based soil and vegetation data. The first scenario applied seasonal changes in vegetative roughness, quantifying the effect on flood peaks at catchment scale. The second scenario modelled the influence of grassland management from historical high-intensity grazing to a series of natural succession stages between grassland and woodland, and a conservation-based management. Model outputs were analysed by flow type, measuring total, overland and base flow peaks at the catchment outlet. Seasonal changes to vegetation were found to increase overland flow peaks by up to +2.2% in winter and reduce them by −5.5% in summer compared to the annual average. Percentage changes in flood peak due to hillslope grassland management scenarios were more substantial; overland flow peaks were reduced by up to 41% in Calderdale where extensive woodland development was the most effective mitigation strategy, and up to 35% in Swindale, where a rank grassland dominated catchment was the most effective. Conservation-based farming practices were also useful, reducing overland flow peak by up to 42% compared to the high intensity grazing scenario. Neither management nor seasonality changed the timing of runoff peaks by >45 min. Where overland flow dominates, especially in catchments with shallow soils, surface roughness was found to be more influential than soil permeability for flood mitigation. We recommend that seasonal changes to roughness are considered alongside the spatial distribution of Natural Flood Management in mosaiced upland catchments

Evaluating the effectiveness of land use management as a natural flood management intervention in reducing the impact of flooding for an upland catchment

Natural flood management (NFM) is a method for reducing flooding by using a catchment-based approach to managing flood risk. Understanding and quantifying the impact of implementing NFM at the catchment scale remains ambiguous with a clear need for robust empirical evidence. A combination of fieldwork, laboratory analysis and modelling was applied to quantify the impacts of land use management changes on catchment flood hazard. Soil hydraulic conductivity was measured under varying land management regimes and used to parameterize a physically based spatially distributed hydrological model (SD-TOPMODEL). A suite of stakeholder informed land management scenarios was modelled, permitting the quantification of the impact of NFM interventions on the timing and the intensity of the peak discharge at the catchment outlet. The findings support the implementation of NFM interventions as a means of reducing flood hazard within a rural upland catchment. Improved soil infiltration provided the greatest reduction in the intensity and delayed timing of the flood peak for a 10-year occurrence storm event (7% reduction in peak runoff and 8% increase in lag time) with similar reductions observed for a 100-year storm event. Catchment wide woodland planting reduced peak flow by 11% during the 100-year event but was not effective during the 10-year event. Riparian buffer strips provided consistent reductions in peak flow and in the timing of the peak across both storm events with no significant differences relating to vegetation age. Critically, we observed that the effect of implementing multiple NFM interventions was not additive and that efficiencies can be made in using this modelling approach to prioritize the most effective outcomes

Low flow controls on stream thermal dynamics

Water level fluctuations in surface water bodies, and in particular low flow drought conditions, are expected to become more frequent and more severe in the future due to the impacts of global environmental change. Variations in water level, and therefore in-channel water volume, not only have the potential to directly impact stream temperature, but also aquatic vegetation coverage which, in turn, may affect stream temperature patterns and dynamics. Manipulation experiments provide a systematic approach to investigate the multiple environmental controls on stream temperature patterns. This study aims to use temperature data loggers and fibre optic distributed temperature sensing (FO-DTS) to investigate potential drought impacts on patterns in surface water and streambed temperature as a function of change in water column depth. To quantify the joint impacts of water level and associated vegetation coverage on stream temperatures, investigations were conducted in outdoor flumes using identical pool-riffle-pool features, but with spatially variable water levels representative of different drought severity conditions. Naturally evolved vegetation growth in the flumes ranged from sparse vegetation coverage in the shallow flumes to dense colonization in the deepest. Observed surface water and streambed temperature patterns differed significantly within the range of water levels and degrees of vegetation coverage studied. Streambed temperature patterns were more pronounced in the shallowest flume, with minimum and maximum temperature values and diurnal temperature variation being more intensively affected by variation in meteorological conditions than daily average temperatures. Spatial patterns in streambed temperature correlated strongly with morphologic features in all flumes, with riffles coinciding with the highest temperatures, and pools representing areas with the lowest temperatures. In particular, the shallowest flume (comprising multiple exposed features) exhibited a maximum upstream-downstream temperature warming of 3.3 °C (T in = 10.3 °C, T out = 13.5 °C), exceeding the warming observed in the deeper flumes by ∼ 2 °C. Our study reveals significant streambed and water temperature variation caused by the combined impacts of water level and related vegetation coverage. These results highlight the importance of maintaining minimum water levels in lowland rivers during droughts for buffering the impacts of atmospheric forcing on both river and streambed water temperatures

Intrinsic molecular signature of breast cancer in a population-based cohort of 412 patients

BACKGROUND: Molecular markers and the rich biological information they contain have great potential for cancer diagnosis, prognostication and therapy prediction. So far, however, they have not superseded routine histopathology and staging criteria, partly because the few studies performed on molecular subtyping have had little validation and limited clinical characterization. METHODS: We obtained gene expression and clinical data for 412 breast cancers obtained from population-based cohorts of patients from Stockholm and Uppsala, Sweden. Using the intrinsic set of approximately 500 genes derived in the Norway/Stanford breast cancer data, we validated the existence of five molecular subtypes – basal-like, ERBB2, luminal A/B and normal-like – and characterized these subtypes extensively with the use of conventional clinical variables. RESULTS: We found an overall 77.5% concordance between the centroid prediction of the Swedish cohort by using the Norway/Stanford signature and the k-means clustering performed internally within the Swedish cohort. The highest rate of discordant assignments occurred between the luminal A and luminal B subtypes and between the luminal B and ERBB2 subtypes. The subtypes varied significantly in terms of grade (p < 0.001), p53 mutation (p < 0.001) and genomic instability (p = 0.01), but surprisingly there was little difference in lymph-node metastasis (p = 0.31). Furthermore, current users of hormone-replacement therapy were strikingly over-represented in the normal-like subgroup (p < 0.001). Separate analyses of the patients who received endocrine therapy and those who did not receive any adjuvant therapy supported the previous hypothesis that the basal-like subtype responded to adjuvant treatment, whereas the ERBB2 and luminal B subtypes were poor responders. CONCLUSION: We found that the intrinsic molecular subtypes of breast cancer are broadly present in a diverse collection of patients from a population-based cohort in Sweden. The intrinsic gene set, originally selected to reveal stable tumor characteristics, was shown to have a strong correlation with progression-related properties such as grade, p53 mutation and genomic instability