Geoenvironmental engineering has evolved rapidly in recent years, merging geotechnical and environmental engineering to tackle complex soil - environmental challenges. By integrating these disciplines, we can create infrastructure projects that are not only structurally sound but also environmentally sustainable. For instance, the EU COST action “Circular Cities” appraise real world environmental challenges like transforming today’s cities into sustainable ones by introducing Nature Based Solutions in the urban landscape. It includes comprehensive interdisciplinary efforts on identification, analyses and reporting about the existing state of the art, as well as research of novel possibilities for Nature Based Solutions implementations in urban areas.
This issue contains a diverse selection of ten accepted papers that research various topics in this field.
Groundwater, estimated on approximately 99% of all liquid freshwater on Earth is the most important water resource for water supply of population and irrigation purposes. According to the United Nations World Water Development Report, 2022, nearly half of the volume of the demands for domestic use of global population as well as 25% of the total irrigation requirements are met by groundwater withdrawal. Therefore, groundwater quality remains one of the crucial environmental concerns. Sun et al. (2024a) in their review paper present the complex interaction between arsenic, organic matter and iron and their impact on arsenic transformation and propagation in groundwater. Their work enhances the knowledge of mechanism of arsenic pollution, controlling the migration and reducing pollution.
Understanding the migration mechanism of contaminants in soils and groundwater becomes essential for remediation of contaminated sites. Wu et al. (2024) analyse the relationship between chlorohydrocarbon contaminants spatial distribution characteristics and soil layer distributions in the Shanghai’s soils. Authors propose six conceptual models for distribution of chlorohydrocarbon contaminants in different zones, which can be used for preliminary assessment of the maximum depth of the chlorohydrocarbon contaminant and the possible enrichment zone of the contaminant.
Phenolic compounds are among the main organic pollutants, currently regarded as priority pollutants due to their increasing concentrations in fresh water bodies and their potential to threat environmental safety and cause detrimental health effects. Wastewater, agricultural runoff, and industrial effluents are major contributors to environmental pollution. He et al. (2024) in their research are focused on phenolic waste water treatment using sodium bentonite, modified with cetyltrimethylammonium bromide to remove phenol from an aqueous solution. The authors investigated the dependency of phenol adsorption on adsorption time, initial phenol concentration and cetyltrimethylammonium bromide — bentonite dosage. The main finding of the research suggests that incorporating an appropriate amount of organic bentonite into bentonite could effectively improve its adsorption performance, as well as its potential to serve as an efficient adsorbent for phenolic waste water treatment.
Chen et al. (2024) researched the possibility to improve the removal efficiency of phenol in saline environment by a composite material consisted of sugarcane biochar and bentonite (SuBC@Ben). The adsorption properties of the bentonite, sugarcane biochar and SuBC@Ben composite with a high adsorption capacity for phenol were analysed for different initial solution concentrations, contact times, initial PH values of the solution and temperatures. Experiments were conducted to assess the permeability of bentonite and the SuBC@Ben composite in saline and acidic aqueous solutions. The authors found that the SuBC@Ben composite exhibited excellent impermeability in saline environments. Therefore, they propose the application of SuBC@Ben in removing phenol as a simple and low cost impermeable adsorption material.
Landfilling is one of the oldest and most widely used methods for solid waste management. Despite being at the bottom of the waste management hierarchy, it still remains prevalent. Landfill gas, leachate, and heat are key byproducts of solid waste decomposition in landfills. Shi et al. (2024) constructed a double layered bioreactor for estimating the heat generated in the process of decomposition of organic components of the municipal solid waste. The waste degradation tests included measurement of variations of waste temperature, ambient temperature, gas emissions and total degraded organic matter for two different initial waste temperatures and ambient temperatures. The authors found that at the beginning of the degradation period the waste temperatures increase rapidly, followed by slower continuous decrease to nearly ambient temperature. They presented that variations in the total generated heat over time can be accurately predicted using an empirical formula. This formula allows for the estimation of heat parameters based on measured temperature fluctuations.
Clay plays a significant role in various engineering disciplines, particularly in geotechnical and environmental engineering. It has been also utilized as a construction material for centuries, valued for its unique properties and versatility. While it offers many advantages, careful consideration of its properties and potential challenges is essential for successful engineering design and implementation. Li et al. (2004) analyse the influence of the pH value on the hydrophysical properties of red clay while Al-Moadhen et al. (2024) present the results of electrical conductivity measurements of sand-clay mixtures. Both groups of researchers modelled challenges with established and proved methodology, simulating different and extensive possible conditions, implementing contemporary tools, aiding to improving the knowledge about the clay and clay mixtures properties.
Natural fibres and fibre composite materials present a friendly alternative to conventional materials, offering numerous environmental and functional benefits. Understanding their long-term performance is crucial for ensuring their effective and sustainable implementation in a wide range of engineering projects. Reis et al. (2024) carried out a comprehensive triaxial testing to analyse the mechanical behaviour of coir -fibre-reinforced soils. The authors found that coir -fibre-reinforced soils may be used in temporary earthworks like landfill final cover.
This issue also considers findings of the numerical investigation of hydrolysis failure of aggregates in loess (Sun et al., 2024b) and about unsaturated characteristics and transport of hydrated chromium ore processing residue (Eun et al., 2024).
The diversity of the researched topics presented in this issue reflects the ongoing progression in this field. As new challenges arise in environmental and geotechnical engineering, these advancements play a crucial role in addressing issues like soil and groundwater contamination, landfilling and sustainable construction practices. By focusing on sustainability and resilience in engineering projects (Reddy et al., 2024), we can shape a future where infrastructure and the environment coexist harmoniously. The Guest Editor hopes the papers in this issue provide invaluable and intricate knowledge in the area, necessary for the next generation of geoenvironmental researchers.
