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Today the design processes in the aero industry face many challenges. Apart from automation itself, a suitable parametric geometry setup plays a significant role in making workflows usable for optimization. At the same time there are tough requirements against the parametric model. For the lowest number of possible parameters, which should be intuitively ascertainable, a high flexibility has to be ensured. Within the parameter range an acceptable stability is necessary. Under these constraints the creation of such parametric models is a challenge, which should not be underestimated especially for a complex geometry.
In this work different kinds of parametrization with different levels of complexity will be introduced and compared. Thereby several geometry elements will be used to handle the critical regions of the geometry. In the simplest case a combination of lines and arcs will be applied. These will be replaced by superior elements like a double arc construct or different formulations of b-splines. There will be an additional focus on the variation of spline degree and control points. To guarantee consistency a set of general parameters will be used next to the specific ones at the critical regions. The different parameter boundaries have a influence on the possible geometries and should therefore be tested separately before an optimization run.
Editorial for the Special Issue “Anthropogenic Geomorphology – Geomorphology in the Anthropocene”
(2023)
Soils of former Manufactured Gas Plants (MGPs) are often contaminated with iron-cyanide (Fe-CN) complexes that originate from gas purification process. Cyanide is a potentially toxic substance and its presence in soil and groundwater may cause risk for human health as well as for the environment. MGPs were commonly built on the city suburban areas, which have spread ever since. Nowadays, these sites are typically located in inner cities, causing environmental thread, due to the leaching of pollutants. More recently, columns and batch experiments have been used to study fate and mobility of contaminants is soil. The release of iron-cyanide complexes under unsaturated flow conditions was evaluated with eight columns of 30 cm length and a diameter of 5,4 cm. Cyanide concentrations in the collected leachates were measured with Flow Injection Analysis (FIA). Additionally pH, electrical conductivity (EC) and various ion concentrations were determined. In order to compare the release of Fe-CN complexes in saturated conditions a batch experiment was conducted, where in defined time intervals, 1 ml of the extract water phase was analyzed for CN concentration. Study revealed an analogous trend of cyanide release in both experiments indicating primarily the release of formerly dissolved phase (hexacyanoferrates) followed by continual dissolution of ferric ferrocyanide. We conclude that batch experiments, conducted prior to column analysis, can serve as preliminary prediction of the water soluble cyanide fraction under unsaturated conditions.
Organic matter from biological soil crusts induces the initial formation of sandy temperate soils
(2014)
Different development stages of algae-dominated and moss-dominated biological soil crusts (BSCs) were sampled on a natural sand dune (b17 years old) and on an experimental sand dune (b8 years old) along a catena, including gradients of vegetation cover, location on the slope, as well as composition and thickness of BSC organisms in northeastern Germany. The accumulation of BSC-derived organic carbon (OC)was determined for bulk materials and fractions less than 63 μm. The OC composition was characterized by solid-state 13C NMR spectroscopy and the carbohydrate-C signature. 14C contents were determined to assess the origin and dynamics of OC. From the radiocarbon contents, two OC pools were differentiated: recent BSC-derived and lignite-derived “old” OC. Downward movement of OC into the underlying substratewas found only undermoss-dominated BSCs at the old sand dune. BSC-derived OC was mainly composed of carbohydrate-C and, to a lesser extent, alkyl C and N-alkyl C, with considerably higher contributions of alkyl C in the young dune, indicating differences in the composition of extracellular polymeric substances produced by the BSCs with age. This is consistent with higher proportions of water-soluble OC of moss-dominated BSCs at the old dune, which is leached in the underlying substrate and initiates soil formation. Because of the channeling effect of mosses, OC depth translocation along with suspended colloidal substances contribute to OC accumulation in substrates.
The soil in the vicinities of former Manufactured Gas Plant (MGP) sites is commonly contaminated with iron-cyanide complexes (ferric ferrocyanide). The phenomenon of cyanide mobility in soil, according to the literature, is mainly governed by the dissolution and precipitation of ferric ferrocyanide, which is only slightly soluble (<1 mg L¡1) under acidic conditions. In this paper, retention properties of the sandy loam soil and the potential vertical movement of the solid iron-cyanide complexes, co-existing with the dissolution, sorption and precipitation reactions were investigated. Preliminary research conducted on a former MGP site implied colloidal transport of ferric ferricyanide from the initial deposition in the wastes layer towards the sandy loam material (secondary accumulation), which possibly retarded the mobility of cyanide (CN). A series of batch and column experiments were applied in order to investigate the retardation of iron-cyanide complexes by the sandy loam soil. Batch experiments revealed that in circumneutral pH conditions sandy loam material decreases the potassium ferro- and ferricyanide concentration. In column experiments a minor reduction in CN concentration was observed prior to addition of iron sulfide (FeS) layer, which induced the formation of the Prussian blue colloids in circumneutral pH conditions. Precipitated solid iron-cyanide complexes were mechanically filtered by the coherent structure of the investigated soil. Additionally, the reduction of the CN concentration of the percolation solutions by the sandy loam soil was presumably induced due to the formation of potassium manganese iron-cyanide (K2Mn[Fe(CN)6]).
Phytoremediation of sites contaminated with iron cyanides can be performed using poplar and willow trees. Poplar and willow trees were grown in potting substrate spiked with ferrocyanide concentrations of up to 2,000 mg kg-1 for 4 and 8 weeks respectively. Soil solution and leaf tissue of different age were sampled for total cyanide analysis every week. Chlorophyll content in the leaves was determined to quantify cyanide toxicity. Results showed that cyanide in the soil solution of spiked soils differed between treatments and on weekly basis and ranged from 0.5 to 1,200 mg l-1. The maximum cyanide content in willow and poplar leaves was 518 mg kg-1 fresh weight (FW) and 148 mg kg-1 FW respectively. Cyanide accumulated in the leaves increased linearly with increasing cyanide concentration in the soil solution. On the long term, significantly more cyanide was accumulated in old leaf tissue than in young tissue. Chlorophyll content in poplar decreased linearly with increasing cyanide in the soil solution and in leaf tissue, and over time. The inhibitory concentration (IC50) value for poplars after 4 weeks of exposure was 173 mg l-1 and for willow after 8 weeks of exposure—768 mg l-1. Results show that willows tolerate much more cyanide and over a longer period than poplars, making them very appropriate for remediating sites highly contaminated with iron cyanides.
Soil contamination with iron-cyanide complexes is a common problem at former manufactured gas plant (MGP) sites. Dissolution of the cyanide, from Prussian Blue (ferric ferrocyanide), creates an environmental hazard, whereas the risk of groundwater contamination depends on the stability of dissolved iron–cyanide complexes. Lack of a standard leaching method to determine the water-soluble (plant-available) cyanide fraction generates potential limitations for implementing remediation strategies like phytoremediation. Applicability of neutral solution extraction to determine the water-soluble cyanide fraction and the stability of Prussian Blue in surface and near-surface soils of an MGP site in Cottbus, undersaturated and unsaturated water conditions, was studied in column leaching and batch extraction experiments. MGP soils used in the long-term tests varied according to the pH (5.0–7.7) and the total cyanide content (40–1718 mg kg−1). Column leaching, after four months of percolation, still yielded effluent concentrations exceeding the German drinking water limit (> 50 μg L−1) and the solubility of Prussian Blue reported in the literature (< 1 mg L−1) from both alkaline and acidic soils. Long-term (1344 h) extraction of MGP soils with distilled water was sufficient to dissolve 97% of the total cyanide from the slightly alkaline soils and up to 78% from the acidic soils. Both experiments revealed that dissolution of ferric ferrocyanide under circum-neutral pH and oxic water conditions is a function of time, where the released amount is dependent on the soil pH and total cyanide content. Unexpectedly high and continuous solubility of Prussian Blue, both in acidic and slightly alkaline MGP soils, implies the need to introduce an additional cyanide fraction (“readily soluble fraction”) to improve and specify cyanide leaching methods. Long-term extraction of cyanide-contaminated soil in neutral solution seems to be a promising approach to evaluate the potential hazard of groundwater pollution at the MGP sites.
Die zurückliegenden trocken-heißen Sommer haben im Süden Brandenburgs zu zahlreichen Bränden in den dominierenden Kiefernwäldern geführt, einige davon mit katastrophalen Ausmaßen. Dazu gehören die extremen Brandereignisse 2018 bei Treuenbrietzen sowie 2019 bei Jüterbog und Lieberose, die zusammen weit über 1000 ha Waldfläche zerstört und dabei auch Veränderungen der betroffenen Waldböden verursacht haben.
Das seit Mai 2020 von der FNR geförderte Verbundvorhaben Pyrophob befasst sich mit den Auswirkungen von Waldbränden im Süden Brandenburgs auf die Waldökosysteme und mit waldbaulichen Maßnahmen, die mittelfristig zu einer Verringerung der Brandanfälligkeit der Wälder beitragen sollen. Im Rahmen des auf eine fünfjährige Laufzeit ausgelegten Verbundvorhabens finden bodenkundliche Untersuchungen auf zwölf Versuchsflächen bei Treuenbrietzen und Jüterbog statt. An beiden Standorten werden unverbrannte Referenzflächen mit einbezogen. Ergänzend konnten bei Lieberose bereits 2019 nur kurz nach dem Brandgeschehen erste Bodenuntersuchungen durchgeführt werden. Die untersuchten Brandflächen bei Jüterbog und Lieberose sind als Totalreservate ausgewiesen, auf denen auch nach dem Brand waldbauliche Maßnahmen vollständig unterbleiben. Auf den Flächen bei Treuenbrietzen wurden verschiedene Behandlungsvarianten durchgeführt, zu denen auf einem Teil der Flächen die vollständige Entfernung der abgestorbenen Bäume gehörte, während auf anderen Teilflächen Totholz auf der Fläche verblieb.
Ziel der bodenkundlichen Arbeiten in Pyrophob ist zum einen eine Charakterisierung der direkten Auswirkungen des Brandes auf Humus und Mineralboden hinsichtlich des Stoffbestandes und bodenbiologischer Prozesse. Zum anderen wird der Stoffaustrag aus dem Oberboden erfasst. Der etwaige Einfluss der unterschiedlichen waldbaulichen Vorgehensweise auf die Bodenverhältnisse wird dabei als ein Indikator für die Auswahl geeigneter Maßnahmen berücksichtigt.
In den verschiedenen Untersuchungsvarianten des Vorhabens wurden zu diesem Zweck Humus- und Mineralbodenprofile untersucht. Zudem wurden Mischproben aus dem Ober- und Unterboden entnommen und auf ihren Stoffhaushalt hin analysiert. Auf jeder Untersuchungsfläche wurden je drei frei dränende Kleinlysimeter in 10 cm Bodentiefe installiert, um die zeitlichen Veränderungen der Sickerwasserzusammensetzung und die durch den Brand initiierten Stoffausträge aus dem Oberboden zu quantifizieren. Ergänzend finden Untersuchungen zu möglichen Auswirkungen der Brände auf bodenbiologische Prozesse wie Streuabbau und Stickstoffmineralisation statt.
For next-generation weather and climate numerical models to resolve cities, both higher spatial resolution and sub-grid parameterizations of urban canopy-atmosphere processes are required. Key is to better understand intra-urban variability and urban-rural differences in atmospheric boundary layer (ABL) dynamics. This includes upwind-downwind effects due to cities’ influences on the atmosphere beyond their boundaries. To address these aspects a network of >25 ground-based remote-sensing sites was designed for the Berlin region (Germany), considering city form, function, and typical weather conditions. This allows investigation of how different urban densities and human activities impact ABL dynamics. As part of the interdisciplinary European Research Council Grant urbisphere, the network was operated from Autumn 2021 to Autumn 2022. Here we provide an overview of the scientific aims, campaign setup, and results from two days, highlighting multi-scale urban impacts on the atmosphere in combination with high-resolution numerical modeling at 100 m grid-spacing. During a spring day, the analyzes show systematic upwind-city-downwind effects in ABL heights, largely driven by urban-rural differences in surface heat fluxes. During a heatwave day, ABL height is remarkably deep, yet spatial differences in ABL heights are less pronounced due to overall dry soil conditions, resulting in similar observed surface heat fluxes. Our modeling results provide further insights into ABL characteristics not resolved by the observation network, highlighting synergies between both approaches. Our data and findings will support modeling to help deliver services to a wider community from citizens to those managing health, energy, transport, land-use and other city infrastructure and operations.