Heavy metal pollution index calculation in geochemistry assessment: a case study on Playa Las Petroleras.

This work is aimed to assess potential risk associated with the presence of metals and metalloids in soil at "Playa Las Petroleras" sector, located in Antofagasta (Chile). The zone under study has been affected by four oil spill events. This sector is located in an urban area by the sea. So, it has a great social and environmental relevance. The concentrations of 15 elements in soil samples were assessed, four of them presenting potential ecological risk: As, Co, Cu, and Pb. Nine pollution indices were applied to data: four single pollution indices and five integrated pollution indices to assess soil pollution. The single pollution indices show that the site bears potential ecological and environmental risk due to the presence of Cu, the site being classified as highly contaminated owing to a severe enrichment of this metal. For Co, all the indices allow classifying the site as little or uncontaminated, while the level of As and Pb pollution could be considered as ranging from uncontaminated to moderately contaminated. The integrated pollution indices show that average concentrations are highly contaminated mainly owing to the presence of Cu.

Uptake of potentially toxic elements by edible plants in experimental mining Technosols: preliminary assessment.

A study was carried out to evaluate the absorption of potentially toxic elements from mining Technosols by three types of vegetable plants (broccoli (Brassica oleracea var. italica), lettuce (Lactuca sativa) and onion (Allium cepa)), the different parts of which are intended for human and farm animal consumption (leaves, roots, edible parts). The preliminary results obtained highlight the importance of the design of the mining Technosols used for agricultural purposes, obtained from soils and sediments of mining origin and amended with residues of high calcium carbonate concentrations (limestone filler and construction and demolition wastes). The experiment was carried out in a greenhouse, and the total metal(loid)s concentration (As, Pb, Cd, Cu, Fe, Mn and Zn) of the soil, rhizosphere, aqueous leachates and plant samples was monitored, the translocation and bioconcentration factors (TF and BCF, respectively) being calculated. The characterization of the soils included a mobilization study in media simulating different environmental conditions that can affect these soils and predicting the differences in behavior of each Technosol. The results obtained showed that the levels of potentially toxic elements present in the cultivated species are within the range of values mentioned in the literature when they were cultivated in soils with calcareous amendments. However, when the plants were grown in contaminated soils, the potentially toxic elements levels varied greatly according to the species, being higher in onions than in lettuce. Experiments with the use of lime filler or construction and demolition wastes for soil remediation result in crops that, in principle, do not present health risks and are similar in development to those grown on non-contaminated soil.

Assessment and abatement of the eco-risk caused by mine spoils in the dry subtropical climate.

The highly rugged mountainous land topography of the Novorossiysk industrial agglomeration (NW Caucasus, Krasnodar Krai, Russia) and arid climate limit the restoration abilities of disturbed mine lands. Abandoned waste-rock dumps of a marl quarry occupy an area of ca. 150,000 m2 next to the cement plant, residential districts, and a commercial seaport. To assess the eco-risk, topsoil horizons of urban and mine-site Technosols and background Rendzinas were sampled and analyzed; measurements of particulate matter fractions PM1, PM2.5, PM4, and PM10 were conducted throughout the agglomeration. Fugitive dust emission from the unreclaimed marl dumps raises the PM2.5 content in the air by a factor of 2.68 on average. The high sorption capacity of the fine eluvium results in the accumulation of urban emissions by the dust and contributes to the subsequent soil pollution; the Cumulative Pollution Index of pedochemical anomalies reaches the high-risk level over the areas of up to 5 km2. Environmental threats caused by the mine dumps can be assessed more reliably by means of land zoning based on accumulated environmental damage indicators and the debris flow and waterspout risk calculation. To abate the technogenic impact caused by the mine spoils, reclamation actions must be taken including soil stabilization on sensitive sites by application of geosynthetic cover, hydroseeding of the mixture of soil improvers and seeds of herbaceous plants on the slopes, and anti-erosion plantation of cades (Juniperus oxycedrus L.) and smoke trees (Cotinus coggygria Scop.) at subhorizontal surfaces.

Assessment of risk from lead intake in mining areas: proposal of indicators.

This study discusses an estimate of the risk associated with the intake of soil contaminated by lead, based on the nature of the source, through a detailed study of the parameters that can influence the bioaccessibility of the element from soil intake. Statistical variables that are related to the solubility and bioavailability of lead are used for this purpose. This includes considering the values of pH, electrical conductivity, particle size, mineralogical composition and the bioaccessibility/bioasimilability of lead. Obtaining an algorithm, represented by different probability distributions of the parameters considered, needs a thorough knowledge of the source materials, which may allow estimating/evaluating the intake health risk provided by the concentration of the metal present. The selected materials are from sites affected by mining activities in the Region of Murcia (SE of Spain) and soils in nearby areas, using a total of 186 samples. Soil samples, once screened and homogenized, were parameterized by determining pH, electrical conductivity, granulometry, both total and water-extractable Pb content. Oral bioaccessibility tests were also performed, and a detailed mineralogical analysis by X-ray diffraction was carried out.

Ecological risk assessment of mercury and chromium in greenhouse soils.

Very little information is available about Hg and Cr evolution in greenhouse soils. This paper presents the results of determining Hg and Cr in greenhouse soils in a semi-arid region in the southern Iberian Peninsula (Almería, Spain), and assessing the enrichment level and the Potential Ecological Risk Index (PERI) according to crop age. Hakanson's approach was used to evaluate the PERI. To investigate the behaviour of Hg and Cr in greenhouse soils over time, samples were grouped into values in soils for blocks according to crop age: 0 years, 5-10 years, 10-20 years, more than 20 years. The results showed that 74% of GS exceeded the obtained background level (37.1 µg kg-1) for Hg, with 43% (48.9 mg kg-1) for Cr. Temporal patterns indicated that these elements are accumulating in greenhouse soils and this trend was very significant for Hg. After more than 20 intensive crop-farming years, concentrations and the PERI had clearly increased. Although the ecological risk was moderate, our observations suggest that the farming practices performed in the last 35 years have allowed these metals to accumulate. In fact, the 15% of the studied soils presented a considerable potential risk and were the soils that had been used longer.