High permeability explains the vulnerability of the carbon store in drained tropical peatlands

Tropical peatlands are an important global carbon (C) store but are threatened by drainage for palm oil and wood pulp production. The store's stability depends on the dynamics of the peatland water table, which in turn depend on peat permeability. We found that an example of the most abundant type of tropical peatland—ombrotrophic domes—has an unexpectedly high permeability similar to that of gravel. Using computer simulations of a natural peat dome (NPD) and a ditch-drained peat dome (DPD) we explored how such high permeability affects water tables and peat decay. High permeability has little effect on NPD water tables because of low hydraulic gradients from the center to the margin of the peatland. In contrast, DPD water tables are consistently deep, leaving the upper meter of peat exposed to rapid decay. Our results reveal why ditch drainage precipitates a rapid destabilization of the tropical peatland C store

Sediment structure and physicochemical changes following tidal inundation at a large open coast managed realignment site

Managed realignment (MR) schemes are being implemented to compensate for the loss of intertidal saltmarsh habitats by breaching flood defences and inundating the formerly defended coastal hinterland. However, studies have shown that MR sites have lower biodiversity than anticipated, which has been linked with anoxia and poor drainage resulting from compaction and the collapse of sediment pore space caused by the site's former terrestrial land use. Despite this proposed link between biodiversity and soil structure, the evolution of the sediment sub-surface following site inundation has rarely been examined, particularly over the early stages of the terrestrial to marine or estuarine transition. This paper presents a novel combination of broad- and intensive-scale analysis of the sub-surface evolution of the Medmerry Managed Realignment Site (West Sussex, UK) in the three years following site inundation. Repeated broad-scale sediment physiochemical datasets are analysed to assess the early changes in the sediment subsurface and the preservation of the former terrestrial surface, comparing four locations of different former land uses. Additionally, for two of these locations, high-intensity 3D-computed X-ray microtomography and Itrax micro-X-ray fluorescence spectrometry analyses are presented. Results provide new data on differences in sediment properties and structure related to the former land use, indicating that increased agricultural activity leads to increased compaction and reduced porosity. The presence of anoxic conditions, indicative of poor hydrological connectivity between the terrestrial and post-inundation intertidal sediment facies, was only detected at one site. This site has experienced the highest rate of accretion over the terrestrial surface (ca. 7 cm over 36 months), suggesting that poor drainage is caused by the interaction (or lack of) between sediment facies rather than the former land use. This has significant implications for the design of future MR sites in terms of preparing sites, their anticipated evolution, and the delivery of ecosystem services

Borehole water level response to barometric pressure as an indicator of aquifer vulnerability

The response of borehole water levels to barometric pressure changes in semiconfined aquifers can be used to determine barometric response functions from which aquifer and confining layer properties can be obtained. Following earlier work on barometric response functions and aquifer confinement, we explore the barometric response function as a tool to improve the assessment of groundwater vulnerability in semiconfined aquifers, illustrated through records from two contrasting boreholes in the semiconfined Chalk Aquifer, East Yorkshire, UK. After removal of recharge and Earth tide influences on the water level signal, barometric response functions were estimated and aquifer and confining layer properties determined through an analytical model of borehole water level response to barometric pressure. A link between the thickness and vertical diffusivity of the confining layer determined from the barometric response function, and groundwater vulnerability is proposed. The amplitude spectrum for barometric pressure and instrument resolution favor determination of the barometric response function at frequencies to which confining layer diffusivities are most sensitive. Numerical modeling indicates that while the high frequency response reflects confining layer properties in the immediate vicinity of the borehole, the low frequency response reflects vertical, high diffusivity pathways though the confining layer some hundreds of meters distant. A characteristic time scale parameter, based on vertical diffusivities and thicknesses of the saturated and unsaturated confining layer, is introduced as a measure of semiconfined aquifer vulnerability. The study demonstrates that the barometric response function has potential as a tool for quantitative aquifer vulnerability assessment in semiconfined aquifers

Salt-freshwater dynamics in a subterranean estuary over a spring-neap tidal cycle

This paper presents field measurements and numerical simulations of pore water salinities and groundwater flow in the intertidal zone of an unconfined coastal aquifer over a spring-neap tidal cycle. The study provides insight into the extent and time-scales of mixing between fresh groundwater and recirculating seawater in a tidally influenced subterranean estuary. Salt-freshwater dynamics in subterranean estuaries are currently not well understood despite their potentially important implications for fluxes of chemicals to coastal waters via submarine groundwater discharge. The data and simulation results show that changes in the tidal shoreline excursion over the spring-neap cycle induce significant variations in the intertidal salinity structure. Observed higher frequency salinity fluctuations demonstrate further the intensity and complexity of the salt-freshwater mixing process. In contrast with the salinity variations, fresh groundwater was found to discharge around a distinct intertidal beach slope break throughout the spring-neap period. This suggests that the slope break may affect significantly groundwater flow and salt transport near the shore. Measurements of pH and dissolved oxygen distributions revealed important biogeochemical zonations in the system. These zonations are expected to strongly influence the fate of many reactive chemicals in the nearshore aquifer and their subsequent discharge to coastal waters

There is no such thing as ‘undisturbed’ soil and sediment sampling: sampler-induced deformation of salt marsh sediments revealed by 3D X-ray computed tomography

Purpose: Within most environmental contexts, the collection of 'undisturbed' samples is widely relied-upon in studies of soil and sediment properties and structure. However, the impact of sampler-induced disturbance is rarely acknowledged, despite the potential significance of modification to sediment structure for the robustness of data interpretation. In this study, 3D-computed X-ray microtomography (μCT) is used to evaluate and compare the disturbance imparted by four commonly-used sediment sampling methods within a coastal salt-marsh. Materials and methods: Paired sediment core samples from a restored salt-marsh at Orplands Farm, Essex, UK were collected using four common sampling methods (push, cut, hammer and gouge methods). Sampling using two different area-ratio cores resulted in a total of 16 cores that were scanned using 3D X-Ray computed tomography, to identify and evaluate sediment structural properties of samples that can be attributed to sampling method. Results and discussion: 3D qualitative analysis identifies a suite of sampling-disturbance structures including gross-scale changes to sediment integrity and substantial modification of pore-space, structure and distribution, independent of sediment strength and stiffness. Quantitative assessment of changes to pore-space and sediment density arising from the four sampling methods offer a means of direct comparison between the impact of depth-sampling methods. Considerable disturbance to samples result from use of push, hammer and auguring samplers, whilst least disturbance is found in samples recovered by cutting and advanced trimming approaches. Conclusions: It is evident that with the small-bore tubes and samplers commonly used in environmental studies, all techniques result in disturbance to sediment structure to a far greater extent than previously reported, revealed by μCT. This work identifies and evaluates for the first time the full nature, extent and significance of internal sediment disturbance arising from common sampling methods

U.S. Waterways Experiment Station Reports

Partial abstract: "The principal subjects of the report are the often neglected changes in the interaction of soil and pressure cells with consequent changes in relative errors in cell registrations. The report contains (a) a brief account of the development and use of soil pressure cells; (b) a review of proposed theories for soil-cell interaction; (c) a delayed account of tests with Waterways Experiment Station pressure cells placed in a large triaxial device; and (d) tentative conclusions plus suggestions for calibration, installation, and measuring procedures.

Varumärkesutveckling i nystartade klädföretag

I mikroföretag samt små- och medelstora företag (SMF) är varumärkesutveckling en avgörande faktor när det kommer till om företaget kommer att lyckas etablera sig på marknaden eller inte. Till skillnad från större organisationer måste SMF, på grund av deras begränsade resurser, tackla arbetet med varumärkesutveckling med ett betydligt större fokus och effektivitet. Inom den svenska modebranschen sysselsätter 95 % av företagen färre än 10 personer, vilket innebär att 95 % av företagen i den svenska modebranschen tillhör kategorin mikro inom SMF. De företag som sysselsätter fler än 250 personer, utgör endast 0,1 % av modeföretagen i Sverige. Trots detta råder det en brist på forskning och litteratur rörande varumärkesutveckling inom SMF. Tidigare forskning och litteratur fokuseras till stora delar på stora- multinationella företag och deras varumärkesutvecklande aktiviteter är oftast varken lämpliga, eller logiska, att tillämpa inom SMF. Denna brist på uppmärksamhet ligger till grund för studiens syfte. Syftet är att granska hur nystartade klädvarumärken, med begränsade resurser, arbetar med varumärkesutveckling för att etablera sitt varumärke. Med hjälp av fyra företag från Borås kommun, grundade mellan år 2013 och 2016, som alla är verksamma inom kläd-/modebranschen har det empiriska underlaget för studien skapats. Tidigare forskning rörande varumärkesutveckling inom SMF har lagt grunden för den teoretiska referensramen. Studien har under intervjuerna, samt analysen av empirin, använt sig av en egenformad teoretisk modell. Den insamlade empirin har sedan kopplats tillbaka till teorin och tidigare forskningsresultat. Studien visar att entreprenörers personliga bakgrunder kan påverka hur entreprenörer i nystartade klädvarumärken arbetar med varumärkesutveckling. Där framförallt entreprenörernas personliga intressen leder till att entreprenörerna arbetar mer med de varumärkesutvecklande aktiviteter som de är intresserade av. Studien visar även att entreprenörer i nystartade klädvarumärken ser varumärkesutveckling som en viktig del i varumärkets förutsättning att nå en etablering på marknaden, där kommunikation med externa intressenter är den stora delen. Studien visar till sist att nystartade klädvarumärken till största del arbetar med varumärkesutvecklande aktiviter som kräver en liten budget eller som är gratis, som ett resultat av att nystartade klädvarumärken har begränsat med resurser