Lucia Belen Martínez

Heavy metal immobilisation by limestone filler in soils contaminated by mining activities: Effects on metal leaching and ecotoxicity

The leachability and ecotoxicity of potentially toxic elements (PTE) eluting from technosols formed of soils affected by mining activities and limestone filler were evaluated. A total of four contaminated soils affected by opencast mining were selected and mixed with limestone filler at three percentages: 10, 20 and 30 %, providing 12 stabilised samples. Total and soluble PTE content (As, Cd, Cu, Fe, Pb and Zn) was determined in all the samples and the Microtox® bioassay was applied to determine the ecotoxicological effect. The stabilised material had a neutral pH and low soluble PTE concentration. Moreover, the ecotoxicological assay indicated the presence of low toxicity levels in the stabilised samples. The applied bioassay can be considered a good tool for the screening of PTE contamination in areas affected by mining activities, while providing information about possible attenuation processes.

Potential bioavailability assessment and distribution of heavy metal(oids) in cores from Portman Bay (SE, Spain)

A total of 120 sediments from 12 cores of Portman Bay (SE Spain) were studied to assess the degree of contamination and ecological risk related to potentially toxic elements (PTEs) by combining a geochemical and mineralogical characterization with the assessment of the bioavailable forms of trace metals (As, Cd, Cu, Fe, Pb, Zn). With this purpose, sediment contamination was assessed by total and water-soluble content, and potential bioavailability by the simultaneously extracted metals and acid-volatile sulphides (SEM-AVS) approach, and by an oral bioaccessibility extraction procedure. The sediments are essentially sandy (>80%). The most important minerals are: iron phases such as siderite, iron oxides and hydroxides and pyrite; clay minerals such as clinochlore, greenalite and biotite; and quartz. Occasionally, jarosite and carbonates (calcite and dolomite) appear. The total PTEs content is high whereas the sediments generally have a very low soluble PTE content. The SEM/AVS ratio is less than unity in most samples, indicating that there is enough sulphur so that if there was a release of metals, they could precipitate as sulphides. After the bioaccessibility extraction, the results showed that zinc and cadmium are more bioaccessible in the intestinal environment (alkaline) while the rest of the elements have greater availability in the stomach (acid). Supplementary material: values of pH (1:1 extract) and concentration of different metals and arsenic in the sediments studied is available at https://doi.org/10.6084/m9.figshare.c.4272176

Proposals for the Remediation of Soils Affected by Mining Activities in Southeast Spain

Abstract The zones affected by long-term mining activities are currently of special interest since they represent a contamination focus influencing large areas. These particular sites are usually abbreviated as CAMAs (critical abandoned mining areas). Sierra Minera of Cartagena-La Union is a CAMA with an interesting and valuable ecosystem that needs adequate management tools. Suitable management should be based on the results of a risk assessment procedure, based on proximity to populations or the use that a specific space may have. The risk assessment needs to consider human health and/or ecosystems. The most serious concern in this respect is the behavior and fate of potentially toxic elements such as lead, cadmium, zinc and arsenic, which were present in the raw materials and may be bioavailable. Remediation measures would be based on the natural attenuation of impacts that have occurred in this area and would include neutralization of the acid mine drainage, increase of the natural vegetation favoring the growth of tolerant species (even with low transference factors), and gully regulation in order to avoid spills on crops or at sea.

Ecoefficient In Situ Technologies for the Remediation of Sites Affected by Old Mining Activities: The Case of Portman Bay

Abstract A review of the historical events that caused a serious environmental impact in a zone affected by mining activities was carried out. Portman Bay, located in southeast Spain, is one of the greatest points of mining-metallurgical contamination of the Mediterranean Sea. After an intense mining exploitation, starting in Roman times, the activity ended in 1991, with more than 60 MT of steriles filling the bay. The decision to recover the bay started in 2007, and studies characterizing and analyzing the risks of materials in surface and depth were carried out. At the same time, a pilot project was designed with two experimental areas using Technosols as an in situ recuperation technology, considering both urban and residential use. In addition, an experimental center for the optimization of proposed technology was constructed, and different analyses, such as marine ecotoxicity techniques or artificial wetland experiences, were carried out. Currently the environmental recovery work is being carried out by the Spanish Ministry of Agriculture, Food and Environment.