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Sand is one of the most fundamental construction materials that is of significant importance and widely used for making concrete, plasters, and mortars, and also for filling under floor and basements. Sand-derived functional materials, for instance superhydrophobic sand, which can be used to prepare liquid marble, separate oil-water mixtures, and transport liquids, have recently been a highly topical and promising research field. However, such materials are mainly prepared using valuable surface modification agents via complicated procedures that are difficult for mass-production, which restricted their true applications. Here, we developed a simple, low-cost, and efficient method for the development of sand-based hierarchical micro/nanostructured composite materials with diverse applications. Briefly, micro/nanostructured superhydrophobic sand was synthesized by one-step in situ growth of a network layer of silicone nanofilaments on the surface of sand microparticles, using only one cheap chemical of small molecules of silanes. The as-prepared superhydrophobic sand displays excellent performance in waterproofing, water storage, soil moisturizing, and oil-water separation. Furthermore, sand-supported micro/nanocomposite catalysts were obtained through covalent attachment of polyamines on the surface of silicone nanofilaments. Such composites, packed in a glass column, were used as a simple flow reactor for Knoevenagel condensation reactions. Quantitative amounts of pure products without further purification can be obtained in such a simple way that just allowing the reactants solution flows through the composite catalysts driven by gravity. These results pave the way toward the development of sand-based multifunctional materials with great potential for industrial use, given their versatile functions and excellent performances but easy-to-fabricate, low-cost preparation procedure.

Soil-plant interactions and root water uptake are important factors of the soil-plant-atmosphere continuum. Characterizing root water uptake dynamics in different forest stands can help to predict water stress due to climate change. Governing factors that define tree root water uptake are environmental conditions, soil hydraulic properties, species-specific rooting patterns as well as intra- and interspecific competition. As spatial-temporal patterns of root water uptake cannot be measured directly, simplified assumptions are often either based upon homogenous soil conditions or on a static root water uptake profile. This study combines high-resolution in-situ measurements of water stable isotopes of xylem and soil moisture with a set of 1D soil hydrological and transport models of the vadose zone (Hydrus 1D) to investigate dynamics in root water uptake patterns of two competing tree species in three different forest stands. We measured in-situ water isotopic signature in different soil depths as well as in spruce and beech xylem continuously for two vegetation periods (2021-2022) including two artificial tracer experiments, a wet period in 2021 and a drought period in 2022. Three stands were compared: i) pure beech, ii) pure spruce and iii) mixed beech and spruce, measuring sap flux, leaf water potential, soil moisture, matric potential, throughfall and stemflow. In order to address different factors of soil heterogeneity, the vadose zone is represented by a set of models covering the range of measured soil conditions. Each model is calibrated against soil water content as well as isotope measurements and subsequently related to sap flux measurements. This allows for separating effects of soil heterogeneity and to analyze the interplay of a) stand specific factors, particularly different rooting distributions, interception, and throughfall patterns, and b) soil specific factors, particularly different hydraulic conductivity and plant available water fractions under changing environmental conditions. Results show that this interplay between soil and stand specific factors is crucial under dry conditions, while soil specific factors are of minor importance under wet conditions. This contribution will present and discuss results from this data-driven modelling study and provide information about how well processes are represented in these kind of models.

A vast majority of studies investigating the source depths in the soil of root water uptake with the help of water stable isotopes implicitly assumes that the isotopic signatures of root water uptake and xylem water are identical. In this study we show that this basic assumption is not necessarily valid, since water transport between the root tips and an observed point above the root zone is not instantaneous. However, to our knowledge no study has yet tried to explicitly assess the distribution of water transport velocities within the xylem. With a dye tracer experiment we could visualize how the transport of water through the xylem happens at a wide range of velocities which are distributed unequally throughout the xylem. In an additional virtual experiment we could show that, due to the unequal distribution of transport velocities throughout the xylem, different sampling approaches of water stable isotopes might effectively lead to xylem water samples with different underlying age distributions.

Performance of engineered surfaces can be enhanced by making them hydrophobic or superhydrophobic via coating them with low-surface-energy micro- and nanopatterns. However, the wetting phenomena of particularly irregular shape and spacing (super)hydrophobic patterns such as polysiloxane coatings are not yet fully understood from a microscopic perspective. Here, we show a new method to collect 3D confocal images from irregular polysiloxane micro- and nanorods from a single rod resolution to discuss their wetting response over long liquid/solid interaction times and quantify the length and diameter of these rods. To collect such 3D confocal images, fluorescent dye containing water droplets were left on our superhydrophobic and hydrophobic polysiloxane coated surfaces. Then their liquid/solid interfaces were imaged at different staining scenarios: (i) using different fluorescent dyes, (ii) when the droplets were in contact with surfaces, or (iii) after the droplets were taken away from the surface at the end of staining. Using such staining strategies, we could resolve the micro- and nanorods from root to top and determine their length and diameter, which were then found to be in good agreement with those obtained from their electron microscopy images. 3D confocal images in this paper, for the first time, present the long-time existence of more than one wetting state under the same droplet in contact with surfaces, as well as external and internal three-phase contact lines shifting and pinning. In the end, these findings were used to explain the time-dependent wetting kinetics of our surfaces. We believe that the proposed imaging strategy here will, in the future, be used to study many other irregular patterned (super)antiwetting surfaces to describe their wetting theory, which is today impossible due to the complicated surface geometry of these irregular patterns.

(Super)antiwetting shielding around engineering materials and protecting them against harsh environmental conditions have been achieved via growing various geometry polysiloxane (or silicone) patterns around them by using a droplet-assisted growth method, where the polymerization takes place inside of the water droplets acting as reaction vessels. The size and distribution of these reaction vessels are the main factors in making different geometry silicone patterns; however, very little is known about the fate of these droplets throughout the polymerization. Here, we propose keeping the relative humidity (% RH) inside the reactor stable throughout the polymerization as a new coating parameter to force the size of the reaction vessel water droplets to be the same for building simply shaped silicone rods with controlled geometry and distribution. In this manner, we grew simple geometry cylindric microrods on surfaces and could tune their length, diameter, inter-rod spacing, and thus the (super)hydrophobicity. Here, we also demonstrate that with changes in the amplitude and stability of the % RH, it is possible to fabricate different (super)hydrophobic nanograsses, conical silicone microrods, and isotropic silicone nanofilaments. The proposed new way of tuning initial and in situ reaction vessel droplet size can be used as a single factor to formulate different geometry silicone patterns with tunable dimensions, leading to different roughness and hydrophobicity. To a certain extent, the droplet size-assisted silicone shaping in this work provides a new way to control the length, diameter, morphology, inter-rod spacing, and thus the (super)hydrophobicity of the silicone patterns, especially those in the shape of simple cylindrical microrods. This control over silicone architecting will help to prepare new (super)hydrophobic coatings with more controlled morphology and thus wettability; on the contrary, it will support surface scientists modeling the connection between surface geometry and (super)antiwetting of such irregular pillared surfaces that remain elusive.

Flood marks are rarely utilized in hazard assessment, mainly because of a lack of data availability and accessibility and mistrust in their reliability. Challenging these common assumptions, we present an approach for evaluation and practical utilization of flood marks by the example of the Kinzig River, a Rhine tributary from the Black Forest with a history of severe floods. We combined written documents describing flood marks with field mapping at three study sites and collected information relating to 89 marks – about 50 % of them still preserved – which refer to ≥15 large floods between 1824 and 1991. The inclusion of a detailed historical-mark survey enabled an assessment of changes through time for each flood mark: they extend from small (±15 cm) imprecisions in mark heights to considerable uncertainties in position, height, and displayed date for some modified marks. Plausibility checks with further data nevertheless demonstrated good overall consistency. We then juxtaposed these marks with the current, modeled flood hazard maps. A wide agreement is apparent, in that the large majority of marks are situated at probable heights and within the modeled flooding area associated with extreme floods. For the few exceptions, we see plausible and historically sound reasons in changed local hydraulic conditions by flood protection walls, exceptional processes during a massive ice jam, and possibly also a local underestimation of hazard along Kinzig River tributaries. Overall, this study highlights (1) the broad availability of flood mark data, both on a larger spatial scale and with regard to already vanished marks, and (2) the significance of the marks, verified by further data, and also demonstrates (3) the possibility of a straightforward inclusion in hazard assessment. We thus encourage the systematic collection, maintenance, and integration of flood marks as responsible risk management, not least regarding their value in the wider context of risk awareness and memory.

Despite great scientific and industrial interest in waterproof cellulosic paper, its real world application is hindered by complicated and costly fabrication processes, limitations in scale-up production, and use of organic solvents. Furthermore, simultaneously achieving nonwetting properties and printability on paper surfaces still remains a technical and chemical challenge. Herein, we demonstrate a nonsolvent strategy for scalable and fast fabrication of waterproofing paper through in situ surface engineering with polysilsesquioxane nanorods (PSNRs). Excellent superhydrophobicity is attained on the functionalized paper surface with a water contact angle greater than 160°. Notably, the engineered paper features outstanding printability and writability, as well as greatly enhanced strength and integrity upon prolonged exposure to water (tensile strength ≈ 9.0 MPa). Additionally, the PSNRs concurrently armor paper-based printed items and artwork with waterproofing, self-cleaning, and antimicrobial functionalities without compromising their appearance, readability, and mechanical properties. We also demonstrate that the engineered paper holds the additional advantages of easy processing, low cost, and mechanochemical robustness, which makes it particularly promising for real world applications.