Minska näringsläckage från regnbäddar och säkerställa etablering av vegetation

Urbanisering ökar förtätningen i staden och det blir allt fler hårdgjorda ytor som gör att vatten inte kan infiltrera. Det har skapat en större belastning på ledningsnätet eftersom avrinningen har ökat. Regnbäddar används för att avlasta ledningsnätet genom att fördröja dagvatten men även för att rena dagvatten från olika föroreningar som det för med sig. Ett nettoläckage av näringsämnen vid ett inledande skede har dock observerats från regnbäddar vilket bidrar till vidare övergödning av sjöar och hav. Nettoläckaget tros bero på näring som tillförts för att säkerställa etablering av vegetation. Denna litteraturstudie har haft för avsikt att undersöka olika utformningar av regnbäddars- och olika filtermaterials förmåga att säkerställa etablering av vegetation och samtidigt bidra till en rening av dagvatten. Studien tar även hänsyn till den ståndort som förekommer i regnbäddar och redovisar vilken vegetation som lämpar sig för det. Studien har undersökt filtermaterialen sand, lera, biokol och pimpsten och dess reningseffekt. Det kan konstateras att olika substrat bör användas för rening av olika näringsämnen och att ett substrat med låg infiltrationskapacitet är fördelaktigt för både rening av dagvatten och vegetationen. Vegetationen har en viktig roll i rening av näringsämnen. Växtval bör därför anpassas efter regnbäddens specifika ståndort så att vegetation inte lider av stress, vilket annars kan påverka reningseffekten och etablering.Urbanization increases densification in the city which has increased the amount of hard surfaces that prevent water from infiltrating. This has created a greater load on the pipeline network because the runoff has increased. Rain beds are used to relieve the pipeline network by delaying stormwater but also to clean stormwater from various pollutants that it carries. However, a net leakage of nutrients at an initial stage has been observed from rain beds, which contributes to further eutrophication of lakes and oceans. The net leakage is believed to be caused by nutrients being added to ensure establishment of vegetation. This literature study has intended to investigate different designs of rain beds and different filter material's ability to ensure the establishment of vegetation and at the same time contribute to the purification of stormwater. The study also takes into account the habitat that occurs in rain beds and presents which vegetation is suitable for it. The study has examined the filter materials sand, clay, biochar, and pumice stone and their purification effects. It can be concluded that different substrates should be used for the removal of different nutrients and that a substrate with low infiltration capacity is beneficial for both stormwater treatment and vegetation. Vegetation plays an important role in the removal of nutrients. Therefore, plant selection should be adapted to the specific site conditions of the rain garden so that the vegetation does not suffer from stress, which could otherwise affect the purification efficiency and establishment

Calculation of the effect of random superfluid density on the temperature dependence of the penetration depth

Microscopic variations in composition or structure can lead to nanoscale inhomogeneity in superconducting properties such as the magnetic penetration depth, but measurements of these properties are usually made on longer length scales. We solve a generalized London equation with a non-uniform penetration depth, lambda(r), obtaining an approximate solution for the disorder-averaged Meissner effect. We find that the effective penetration depth is different from the average penetration depth and is sensitive to the details of the disorder. These results indicate the need for caution when interpreting measurements of the penetration depth and its temperature dependence in systems which may be inhomogeneous

Modelling aggregation on the large scale and regularity on the small scale in spatial point pattern datasets

We consider a dependent thinning of a regular point process with the aim of obtaining aggregation on the large scale and regularity on the small scale in the resulting target point process of retained points. Various parametric models for the underlying processes are suggested and the properties of the target point process are studied. Simulation and inference procedures are discussed when a realization of the target point process is observed, depending on whether the thinned points are observed or not. The paper extends previous work by Dietrich Stoyan on interrupted point processes

Bayesian spatial extreme value analysis of maximum temperatures in County Dublin, Ireland

In this study, we begin a comprehensive characterisation of temperature extremes in Ireland for the period 1981-2010. We produce return levels of anomalies of daily maximum temperature extremes for an area over Ireland, for the 30-year period 1981-2010. We employ extreme value theory (EVT) to model the data using the generalised Pareto distribution (GPD) as part of a three-level Bayesian hierarchical model. We use predictive processes in order to solve the computationally difficult problem of modelling data over a very dense spatial field. To our knowledge, this is the first study to combine predictive processes and EVT in this manner. The model is fit using Markov chain Monte Carlo (MCMC) algorithms. Posterior parameter estimates and return level surfaces are produced, in addition to specific site analysis at synoptic stations, including Casement Aerodrome and Dublin Airport. Observational data from the period 2011-2018 is included in this site analysis to determine if there is evidence of a change in the observed extremes. An increase in the frequency of extreme anomalies, but not the severity, is observed for this period. We found that the frequency of observed extreme anomalies from 2011-2018 at the Casement Aerodrome and Phoenix Park synoptic stations exceed the upper bounds of the credible intervals from the model by 20% and 7% respectively

Water sources and mixing in riparian wetlands revealed by tracers and geospatial analysis

Acknowledgments We thank the European Research Council (ERC) (project GA 335910 VEWA) and Natural Environment Research Council (NERC) (project NE/K000268/1) for funding and the Airborne Research and Survey Facility for conducting the aerial survey. The data used are available from the authors. In addition, we would like to thank the additional support from Audrey Innes for the sample analysis and Maria Blumstock and Mike Kennedy for assisting with field work.Peer reviewedPublisher PD

Generalized Whittle-MatEˊ\acute{\text{E}}rn random field as a model of correlated fluctuations

This paper considers a generalization of Gaussian random field with covariance function of Whittle-Mat$\acute{\text{e}}$rn family. Such a random field can be obtained as the solution to the fractional stochastic differential equation with two fractional orders. Asymptotic properties of the covariance functions belonging to this generalized Whittle-Mat$\acute{\text{e}}$rn family are studied, which are used to deduce the sample path properties of the random field. The Whittle-Mat$\acute{\text{e}}$rn field has been widely used in modeling geostatistical data such as sea beam data, wind speed, field temperature and soil data. In this article we show that generalized Whittle-Mat$\acute{\text{e}}$rn field provides a more flexible model for wind speed data.Comment: 22 pages, 10 figures, accepted by Journal of Physics

Outlining multi-purpose forest inventories to assess the ecosystem approach in forestry

A summary and discussion of selected published results on the current and potential role of forest inventories (with particular reference to the national ones) are presented in the light of the challenges posed by society and policy decisions in the environmental sector. The analysis concentrates mainly on the ecological and socio-economic aspects of the question and on forest inventories’ potential contribution to achieving sustainable forest management.L'articolo è diponibile sul sito dell'editore wwww.tandf.co.uk/journals