This is a special issue dedicated to soil and groundwater contamination and remediation. Most of the studies included herein were presented in the 14th International Conference on Environmental Science and Technology (http://cest2015.gnest.org/) that took place in Rhodes Island, Greece in September, 2015. This special issue also hosts studies by other researchers working in this field. Similar to the first special issue (2015), the current special issue does not focus on a specific part of this topic but presents a wide range of different research studies highlighting the topic’s diversity and complexity.

The first part of the special issue hosts studies investigating contamination and remediation in mining sites. In particular, Erdemir et al. evaluate the elemental composition of plant species spread around an abandoned tungsten mining area in Turkey, while Rojo et al. analyze the electrical behavior of tailings in Electro-Kinetic Remediation experiments. Tamburini et al. focus on developing a bioaugmentation-assisted phytostabilization technology based on autochthonous plant species and plant growth promoting bacteria from an abandoned mining area in Italy, which constituted one of the most important mining districts for Pb and Zn extraction. A study investigating also phytoremediation is that of Lai et al., who examine the suitable breeding conditions of Impatiens walleriana, which is a potential cadmium (Cd) hyperaccumulator.

The next two studies investigate the effect of inadequate waste management practices to groundwater and soil quality. The first study by Kavvadias et al. investigates the extent in which the long-term disposal of olive mill wastewaters in evaporation ponds in Greece can affect the soil properties of the area located outside the evaporation pond, while Eze et al. investigate groundwater contamination following improper hospital wastes disposal in Nigeria.

The next part of this special issue focuses on soil and groundwater contaminated with chromium (Cr). In particular, Dermatas et al. compare a site with geogenic Cr(VI) and a site with anthropogenic Cr(VI) and demonstrate how important is the origin of the contaminant for the remediation measures selected, while Dokou et al. develop a groundwater flow and Cr(VI) transport model for the same anthropogenic Cr(VI)-contaminated site. Molla et al. evaluate the removal of chromium from soils cultivated with maize using soil amendments, while Chrysochoou and Reeves study nanoremediation of Cr(VI)-contaminated groundwater using green tea solution and nano zero valent iron (nZVI).

Another study investigating nanoremediation is that of Vilardi and Di Palma who, however, examine the nitrate removal by Cu–Fe nanoparticles and evaluate the optimal ratio between reductant and pollutant. Soil remediation is also studied by Mukhopadhyay et al. who investigate soil washing of arsenic from an iron rich soil using phosphate and colloidal gas aphrons generated from saponin extracted from Sapindus mukorossi fruit.

The next two studies investigate contaminant transport through soil. The first is by Smilek et al. investigating the transport of organic compounds through porous systems containing humic acids and the second by Bourazanis et al. investigating chloride transport through the soil.

Finally, the study of Abou-Shanab et al. investigates bacterial cultures isolated from hydrocarbon contaminated soil, while the study of Mohamed et al. evaluates the groundwater quality in the shallow unconfined alluvial aquifer in the north-eastern part of Abu Dhabi Emirate indicating that agriculture and human activities should be monitored to avoid deterioration of water resources in this region.

The Guest Editors would like to specially thank Dr. Erin Bennett, the Editor-in-chief of the Bulletin of Environmental Contamination and Toxicology, for his help and co-operation and of course the authors and the reviewers participating.