Microplastic pollution on historic facades: Hidden 'sink' or urban threat?

Despite the increasing concerns surrounding the health and environmental risks of microplastics (MPs), the research focus has primarily been on their prevalence in air and the oceans, consequently neglecting their presence on urban facades, which are integral to our everyday environments. Therefore, there is a crucial knowledge gap in comprehending urban MP pollution. Our pioneering interdisciplinary study not only quantifies but also identifies MPs on historic facades, revealing their pervasive presence in a medium-sized urban area in the UK.

The Historic Built Environment As a Long-Term Geochemical Archive: Telling the Time on the Urban "Pollution Clock".

This study introduces a novel methodology for utilizing historic built environments as reliable long-term geochemical archives, addressing a gap in the reconstruction of past anthropogenic pollution levels in urban settings. For the first time, we employ high-resolution laser ablation mass spectrometry for lead isotope (Pb/Pb and Pb/Pb) analysis on 350-year-old black crust stratigraphies found on historic built structures, providing insights into past air pollution signatures. Our findings reveal a gradual shift in the crust stratigraphy toward lower Pb/Pb and higher Pb/Pb isotope ratios from the older to the younger layers, indicating changes in lead sources over time.

Understanding the Microstructure of Mortars for Cultural Heritage Using X-ray CT and MIP.

In this study, the microstructure of mock-up mortar specimens for a historic environment, composed of different mixtures, was studied using mercury intrusion porosity (MIP) and microcomputed tomography (µCT), highlighting the advantages and drawbacks of both techniques. Porosity, sphericity, and pores size distribution were studied, evaluating changes according to mortar composition (aerial and hydraulic binders, quartz sand, and crushed limestone aggregate). The µCT results were rendered using 3D visualization software, which provides complementary information for the interpretation of the data obtained using 3D data-analysis software.

Differential colonization of microbial communities inhabiting Lede stone in the urban and rural environment.

Air pollution is one of the main actors of stone deterioration. It influences not only the material itself but also prokaryotes colonizing rocks. Prokaryotes can affect rock substrates and biological colonization will most likely become relatively more important during the course of the 21st century.

Impact of the urban heat island on freeze-thaw risk of natural stone in the built environment, a case study in Ghent, Belgium.

Freeze-thaw cycles are important in the weathering behaviour of natural building stones in humid, cold to temperate climates. It is expected that the elevated air temperatures in urban environments, the so-called urban heat island (UHI), will have an impact on freeze-thaw weathering. In this study, the impact of the urban heat island on the potential freeze-thaw risk is assessed by parameterization of climatic data of 1 year (07/2016-06/2017) from the MOCCA (Monitoring the City's Climate and Atmosphere) project, which studies the urban heat island in Ghent, Belgium.

Neutron Radiography Study of Laboratory Ageing and Treatment Applications with Stone Consolidants.

A nano-silica consolidant and nano-titania modified tetraethyl-orthosilicate were applied on two building stones, a carbonate and a silicate, by brush, poultice or capillary absorption. Neutron radiography was used to monitor capillary water absorption, and to analyse changes in physical properties caused by heat treatment of specimens for the purposes of artificially ageing and different treatment applications with stone consolidants. Moreover, ultrasonic pulse velocity and gravimetrically determined water absorption were analysed to cross-validate neutron radiography.

In Situ Triaxial Testing To Determine Fracture Permeability and Aperture Distribution for CO Sequestration in Svalbard, Norway.

On Svalbard, Arctic Norway, an unconventional siliciclastic reservoir, relying on (micro)fractures for enhanced fluid flow in a low-permeable system, is investigated as a potential CO sequestration site. The fractures' properties at depth are, however, poorly understood. High resolution X-ray computed tomography (micro-CT) imaging allows one to visualize such geomaterials at reservoir conditions.

Methane Bubble Growth and Migration in Aquatic Sediments Observed by X-ray μCT.

Methane bubble formation and transport is an important component of biogeochemical carbon cycling in aquatic sediments. To improve understanding of how sediment mechanical properties influence bubble growth and transport in freshwater sediments, a 20-day laboratory incubation experiment using homogenized natural clay and sand was performed. Methane bubble development at high resolution was characterized by μCT.

Laminar gypsum crust on lede stone: Microspatial characterization and laboratory acid weathering.

Gypsum crusts are typical decay forms on limestone in polluted urban environments. Their origin and relation to the stone facies have been thoroughly investigated in the past three decades. Here, we present the combined use of novel techniques for a microspatial structural, chemical and mechanical characterization of a laminar black gypsum crust on a sandy limestone.

A pore-scale study of fracture dynamics in rock using X-ray micro-CT under ambient freeze-thaw cycling.

Freeze-thaw cycling stresses many environments which include porous media such as soil, rock and concrete. Climate change can expose new regions and subject others to a changing freeze-thaw frequency. Therefore, understanding and predicting the effect of freeze-thaw cycles is important in environmental science, the built environment and cultural heritage preservation.

Monitoring of stainless-steel slag carbonation using X-ray computed microtomography.

Steel production is one of the largest contributors to industrial CO2 emissions. This industry also generates large amounts of solid byproducts, such as slag and sludge. In this study, fine grained stainless-steel slag (SSS) is valorized to produce compacts with high compressive strength without the use of a hydraulic binder.

High-resolution X-ray CT for 3D petrography of ferruginous sandstone for an investigation of building stone decay.

Diestian ferruginous sandstone has been used as the dominant building stone for monuments in the Hageland, a natural landscape in east-central Belgium. Like all rocks, this stone type is sensitive to weathering. Case hardening was observed in combination with blackening of the exterior parts of the dressed stones.