Remediating Garden Soils: EDTA-Soil Washing and Safe Vegetable Production in Raised Bed Gardens

Soil remediation is an important practice in the restoration of heavy metal-contaminated soils and reduce the heavy metal exposure of the local population. Here, we investigated the effect of an ex-situ soil washing technique, based on ethylenediaminetetraacetic acid (EDTA) as a chelating agent, on a contaminated Cambisol. Lead, Cd and Zn were investigated in different soil fractions, drainage water and four vegetables from August 2019 to March 2021. Three treatments consisting of (C) contaminated soil, (W) washed soil and (WA) washed soil amended with vermicompost and biochar were investigated in an outdoor raised bed set up. Our results showed that the total and bioavailable metal fractions were significantly reduced but failed to meet Austrian national guideline values. Initial concentrations in the soil leachate increased significantly, especially for Cd. Vegetables grown on the remediated soil took up significantly lower amounts of all heavy metals and were further reduced by the organic amendment, attaining acceptable values within EU guideline values for food safety. Only spinach exceeded the thresholds in all soil treatments. The increase in soil pH and nutrient availability led to significantly higher vegetable yields

Exploring the Potential Risk of Heavy Metal Pollution of Edible Cultivated Plants in Urban Gardening Contexts Using a Citizen Science Approach in the Project “Heavy Metal City-Zen”

Urban gardening has become increasingly popular, creating green oases in cities; however, many of these activities are undertaken in areas of high traffic density or on ex-brown field sites. As a consequence, there are still some barriers to the adoption of these urban gardening practices for food production. One of the public concerns is the transfer of urban pollutants such as heavy metals into the consumer’s food chain, however, city-wide data is often difficult and expensive to collect. In the citizen science project described herein, we conducted simple citizen-led common collaborative experiments in urban community gardens. These data provided information on the potential risk of heavy metal contaminants and ways in which to mitigate those risks in an urban gardening context. Generally, values were below guideline thresholds, however, at a few garden sites, soil trace metal concentrations (Pb, Cd, Zn) exceeded Austrian recommended limits. Moreover, only at two sites were plant trace metal concentrations shown to be above European food standards limits. Given the citizen’s positive response to the project, we suggest expanding this study to the whole of Vienna, giving newly established gardens a chance to predetermine the risks posed by their local soils

Unexpected earthquake hazard revealed by Holocene rupture on the Kenchreai Fault (central Greece): Implications for weak sub-fault shear zones

High-resolution elevation models, palaeoseismic trenching, and Quaternary dating demonstrate that the Kenchreai Fault in the eastern Gulf of Corinth (Greece) has ruptured in the Holocene. Along with the adjacent Pisia and Heraion Faults (which ruptured in 1981), our results indicate the presence of closely-spaced and parallel normal faults that are simultaneously active, but at different rates. Such a configuration allows us to address one of the major questions in understanding the earthquake cycle, specifically what controls the distribution of interseismic strain accumulation? Our results imply that the interseismic loading and subsequent earthquakes on these faults are governed by weak shear zones in the underlying ductile crust. In addition, the identification of significant earthquake slip on a fault that does not dominate the late Quaternary geomorphology or vertical coastal motions in the region provides an important lesson in earthquake hazard assessment.This work forms part of the NERCand ESRC-funded project ‘Earthquakes Without Frontiers’, and was partly funded by the NERC grant ‘Looking Inside the Continents from Space’