Núria Bosch Roca

Measuring the efficiency in spanish municipal refuse collection services

The aim of this article is to analyse the technical efficiency of the refuse collection services in 75 municipalities located in Catalonia, Spain. The analysis has been carried out using a great variety of techniques, both parametric and non‐parametric. Although the results naturally differ according to the technique used, they nevertheless are consistent in ranking the units analysed. Finally, we have looked into the relation existing between efficiency and the public or private management of the service. The results seem to support the idea that the framework for competition in which the service is provided could be more relevant than the private‐public management dichotomy.

Remediation of Potentially Toxic Elements in Contaminated Soils

This chapter aims to offer an overview of the main remediation methods of potentially toxic elements in contaminated soils, mainly heavy metals, metalloids and radionuclides, focusing on their essential characteristics, advantages and limitations. It consists of two main groups of technologies: the first group dealing with containment and confinement, minimizing their toxicity, mobility and bioavailability. Containment measures include covering, sealing, encapsulation and immobilization through solidification (cement-based, polyethylene and resine binders, bituminization or asphalt batching and vitrification or glassification) and stabilization with inorganic and organic amendments. The second group, remediation with decontamination is based on the remotion, clean up and/or destruction of contaminants. This group includes mechanical procedures (excavation, transport and disposal to landfills), physical separations, chemical technologies such as soil washing with leaching or precipitation of potentially toxic elements, soil flushing, thermal treatments (desorption, pyrometallurgical processes and incineration) and electrokinetic technologies (electromigration, electroosmosis, electrophoresis and combinations of electrokinetics with other techniques). There are also two approaches of biological nature: bioremediation (biosorption, bioreduction, biomineralization and bioleaching-with some examples from Korea) and phytoremediation (phytoextraction, including chelate-assisted phytoextraction, phytostabilization, phytoremediation in mining activities -with examples from Portugal, Spain, Ecuador, Peru and Chile mainly-, phytovolatilisation and phytomining).

A study of trace elements in plants of the Polar Urals and Chukotka in the search for metallophyte hyperaccumulators

The present study summarizes the results of investigations of the trace element distribution in soils and their uptake by plants of natural habitats on the ultramafic and acidic rocks of the Polar Urals and Chukotka in the Arctic Russia. Concentrations of Fe, Mn, Zn, Cu, Ni, Cr, and Co were determined by atomic absorption spectrometry in 194 plant species of 30 families and 157 soil samples. Two leaches were used for the soil – 1 M ammonium acetate (exchangeable) and 1 M HNO3 (acid soluble); a mixture of 1.5 M HNO3 and 3.7 M HCl was used for the plants. The levels of Fe, Cr and especially Ni in the soils on the ultramafic rocks exceeded those of soils on the acidic rocks. The mineral composition of plant species varies depending on the differences in chemical and mineralogical composition of the two soil-forming rock types. Taxon-specific features in the accumulation of potentially toxic elements in plants of these regions have been revealed for the first time. The data on the metal accumulation ability of plant species show that the species Thlaspi cochleariforme DC. and Alyssum obovatum (C.A. Mey) Turcz. (Brassicaceae) could be considered as Ni hyperaccumulators. These species could therefore have potential for Ni phytoextraction from contaminated soils.

Research of reclamation of polluted mine soils by native metallophytes: some cases.

The aim of this study was to estimate the phytoremediation potential of Brassicaceae plant species growing on mineralized and contaminated soils. The concentrations of six potentially toxic metals (Cd, Cu, Co, Ni, Pb and Zn) in the soils and plants collected from four mining areas of the Karachay-Cherkesia and the Dagestan (the North Caucasus, Russia) were determined. Mine soils showed high acid-soluble and extractable concentrations of: Cu, Zn, at Urup copper ore mining area; Ni, in the Beden serpentine quarry; and Zn and Pb around Kurush-Mazin polymetallic ores. Results demonstrated that metal concentrations in soils were in general above the Russian maximum permissible values. In all studied areas, Brassicaceae were pioneer species, and revealed a high tolerance to soils with high concentrations of potentially toxic metals. Different degrees of accumulating capacity were found in the studied Brassicacaeae species: hyperaccumulation of Ni in Alyssum murale, and significant accumulation of several metals in Arabis sagittata. These species can be used in a cost-effective process of phytoextraction. They are promising species for rehabilitation of degraded and/or contaminated soils of the North Caucasus.