The evaluation of Hudson River sediment as a growth substrate - Microbial activity, PCB-degradation potential and risk assessment

Microbial response to Nature-Based Solutions in urban soils: A comprehensive analysis using Biolog® EcoPlates™

The study presents a comprehensive examination of changes in soil microbial functional diversity (hereafter called microbial activity) following the implementation of Nature-Based Solutions (NBS) in urban areas. Utilizing the Biolog® EcoPlates™ technique, the study explored variations in microbial diversity in urban soil under NBSs implementation across timespan of two years. Significant differences in microbial activity were observed between control location and those with NBS implementations, with seasonal variations playing a crucial role. NBS positively impacted soil microbial activity especially at two locations: infiltration basin and wild flower meadow showing the most substantial increase after NBS implementation. The study links rainfall levels to microbial functional diversity, highlighting the influence of climatic conditions on soil microbiome. The research investigates also the utilization of different carbon sources by soil microorganisms, shedding light on the specificity of substrate utilization across seasons and locations. The results demonstrate that NBSs implementations lead to changes in substrate utilization patterns, emphasizing the positive influence of NBS on soil microbial communities. Likewise, biodiversity indices, such as Shannon-Weaver diversity (H'), Shannon Evenness Index (E), and substrate richness index (S), exhibit significant variations in response to NBS. Notably, NBS implementation positively impacted H' and E indexes, especially in infiltration basin and wild flower meadow, underlining the benefits of NBS for enhancing microbial diversity. The obtained results demonstrated valuable insight into the dynamic interactions between NBS implementation and soil microbial activity. The findings underscore the potential of NBS to positively influence soil microbial diversity in urban environments, contributing to urban sustainability and soil health. The study emphasizes the importance of monitoring soil microbial activity to assess the effectiveness of NBS interventions and guides sustainable urban development practices.

Immobilisation of metals from bottom sediments using two additives and thermal treatment

A major problem associated with the land-based management of bottom sediments is their contamination with metals. The aims of the study were: 1) to use two additives for the immobilisation of metals; and 2) to evaluate the effect of three combustion temperatures on metal content and bottom sediment properties. The mixtures were prepared using contaminated bottom sediment and the following waste materials: cellulosic waste and biomass ash. In the second experiment, the bottom sediment samples were subjected to a thermal process, and three temperatures were chosen 500/800/950 °C. Overall, the addition of cellulosic waste and biomass ash to acidic, metal-contaminated bottom sediments significantly improved the properties of the resulting mixtures, including an increase in the pH value, sorption capacity, macronutrient content, and a decrease in the content and mobility of metals (Cd, Zn, Pb, Cr). The study confirmed the effectiveness of the thermal process on a significant reduction in the ecotoxicity of the sediments, a reduction in total content of elements, and a decrease in their leachability, and thus mobility, with increasing process temperature. The study results revealed that the converted contaminated bottom sediments can be effectively managed, provided that further studies on their technical application are carried out.