No abstract

Although mercury (Hg) mining in the Almadén district ceased in May 2002, the consequences of 2000 years of mining in the district has resulted in the dissemination of Hg into the surrounding environment where it poses an evident risk to biota and human health. This risk needs to be properly evaluated. The uptake of Hg has been found to be plant-specific. To establish the different manners in which plants absorb Hg, we carried out a survey of Hg levels in the soils and plants in the most representative habitats of this Mediterranean area and found that the Hg concentrations varied greatly and were dependent on the sample being tested (0.13-2,695 microg g(-1) Hg). For example, the root samples had concentrations ranging from 0.06 (Oenanthe crocata, Rumex induratus) to 1095 (Polypogon monspeliensis) microg g(-1) Hg, while in the leaf samples, the range was from 0.16 (Cyperus longus) to 1278 (Polypogon monspeliensis) microg g(-1) Hg. There are four well-differentiated patterns of Hg uptake: (1) the rate of uptake is constant, independent of Hg concentration in the soil (e.g., Pistacia lentiscus, Quercus rotundifolia); (2) after an initial linear relationship between uptake and soil concentration, no further increase in Hg(plant) is observed (e.g., Asparagus acutifolius, Cistus ladanifer); (3) no increase in uptake is recorded until a threshold is surpassed, and thereafter a linear relationship between Hg(plant) and Hg(soil) is established (e.g., Rumex bucephalophorus, Cistus crispus); (4) there is no relationship between Hg(plant) and Hg(soil )(e.g., Oenanthe crocata and Cistus monspeliensis). Overall, the Hg concentrations found in plants from the Almadén district clearly reflect the importance of contamination processes throughout the study region.

The Mt. Amiata volcano is the youngest and largest volcanic edifice in Tuscany (central-northern Italy) and is characterized by a geothermal field, exploited for the production of electrical energy. In the past Mt. Amiata was also known as a world-class Hg district whose mining activity was mainly distributed in the central-eastern part of this silicic volcanic complex, and particularly in the municipality of Abbadia San Salvatore. In the present work we report a geochemical survey on Hg(0) measurements related to the former mercury mine facilities prior the reclamation project. The Hg(0) measurements were carried out by car for long distance regional surveys, and on foot for local scale surveys by using two LUMEX (915+ and M) devices. This study presents the very first Hg(0) data obtained with this analytical technique in the Mt. Amiata area. The facilities related to the mining areas and structures where cinnabar was converted to metallic Hg are characterized by high Hg values (>50,000ngm(-3)), although the urban center of Abbadia San Salvatore, few hundred meters away, does not appear to be receiving significant pollution from the calcine area and former industrial edifices, all the recorded values being below the values recommended by the issuing Tuscany Region authorities (300ngm(-3)) and in some cases approaching the Hg background levels (3-5ngm(-3)) for the Mt. Amiata area.

Metallurgic calcines with very high mercury and methylmercury content from the Almadén mining district were analyzed by synchrotron-based microprobe techniques. Information about mercury speciation was obtained by micro-EXAFS (microscopic extended X-ray absorption fine structure) spectroscopy, whereas elemental associations were evaluated by micro-XRF (microscopic X-ray fluorescence analysis) mapping. Complementary characterization methodologies, including X-ray diffraction (XRD), inductively coupled plasma-optical spectroscopy (ICP-OES), as well as a sequential extraction scheme (SES), were used to predict the potential availability of mercury. Analysis of total metal content revealed extremely high concentrations of mercury and iron (between 7 and 35 and 65-70 g kg(-1), respectively) and high zinc concentrations (2.2-2.5 g kg(-1)), whereas other metals such as copper, nickel, and lead were found at low concentration levels (30-300 mg kg(-1)). Micro-EXAFS results indicate that cinnabar (HgS(red)) is one of the main species within the studied mercury-rich particles (5-89% of total mercury content), together with more soluble mercury compounds such as Hg3(SO4)02 (schuetteite) and HgO (5-55% of total mercury content). Additionally, element-specific micro-XRF maps of selected mercury-rich particles in the studied samples revealed an evident correlation among Hg-Pb-Ni (and S), indicating a possible geochemical linkage of these elements. Correlations were also found among Fe-Mn and Hg, which have been attributed to sorption of mercury onto oxyhydroxides of Fe and Mn. This finding was supported by results from a sequential extraction scheme, where a significant

The Cerco de Almadenejos (CDA) is an old metallurgical site located in the province of Ciudad Real (Spain) that operated between 1794 and 1861. The metallurgical precinct was built for the roasting of the Almadén and Almadenejos cinnabar ore to extract Hg metal. A previous pilot geochemical study of soils at the CDA had already shown extremely high concentrations of Hg. To analyze the extent and intensity of contamination, we planned and executed a geochemical survey to cover the CDA and the surrounding areas. The survey covered soils, air, and plants. The planning involved the design of two sampling grids in order to obtain a comprehensive picture of potential environmental hazards in the area: 1) a detailed sampling grid centred on the metallurgical precinct (n = 16 samples; area = 3.6 × 10 4 m 2 ); and 2) a less detailed sampling grid planned to determine the extension of contamination beyond the metallurgical site (n = 35 samples; area = 1.2 × 10 6 m 2 ). After variogram modelization of geochemical data, the kriging plots showed that contamination, even if centred at the precinct, extends beyond the site, with Hg concentrations of up to 2200 times those of uncontaminated soils (world baseline). The detailed study of the soils from the precinct shows an extremely high mean concentration of 4220 μg Hg g − 1 (4.2 × 10 5 times baseline concentration). In turn, these highly polluted soils induce strong emissions of Hg (g) , with concentrations of up to 970 ng Hg m − 3 . The study of the edible wild asparagus Asparagus acutifolius shows extremely high concentrations of mercury in roots (0.6-443 μg g − 1 ) and stems (0.3-140 μg g − 1 ). The data indicate that the study area constitute a hot spot of contamination and is a potential health/environmental hazard for the inhabitants of Almadenejos, livestock, and wild life, that requires immediate action via remediation procedures.

Environmental monitoring, as a prerequisite for environmental risk assessment, is crucial in developing nations from Africa, Latin America, South East Asia, or Melanesia, where conspicuously most of the World's mining activity concentrates. One of the most important environmental problems relates to the disposal of mine concentrates to river systems (e.g., Irian Jaya or Papua New Guinea). However, environmental monitoring is severely restricted in developing countries due to the chronic lack of funds. This paper explores the potential for a wider use of Field Portable X-Ray Fluorescence Spectroscopy instruments (FPXRFs) in fast, real-time, cost-effective environmental surveys for heavy metal dispersal in developing countries, where access to fully equipped geochemical labs is not usually a viable option. We simulated a scenario resembling conditions to be found in a remote region affected by mining-derived metal pollution where no proper laboratory facilities existed. We used an OXFORD X-MET 3000TX XRF analyzer under quasi-realistic conditions, relying solely on the instrument to allow geochemical characterization of a highly polluted Pb-Zn old mining district in the Alcudian Valley of central Spain. Our results for Pb, Zn, Cu, As, and Cd from 12 mine sites showed an excellent performance of the instrument, both under real-time and laboratory conditions. Furthermore, the instrument proved to be fit to endure a variety of field operational conditions and was able to deal with different types of samples, including tailings, soils, and stream sediments. Thus, taking into account the affordability of FPXRFs in relation to bench-top laboratory metal analyzers and their operational simplicity, we suggest that these portable instruments should become 'the equipment of choice' for environmental monitoring in developing countries. In this respect, FPXRFs satisfy the system-independence criterion for sustainable development, i.e., the instrument can stand alone and do its job with few or no other supporting facilities or devices. We go further on these matters providing some hints on how FPXRFs could become widely available via international cooperation, and the technical and social benefits that such equipments could bring to foreign aid recipient countries.

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We present data from a study of mercury concentrations in air and plant specimens from the MAF Herbarium in Madrid (Spain). Hg (gas) emissions from old plant collections treated with mercuric chloride (HgCl(2)) in herbaria may pose a health risk for staff working in installations of this type. This is an issue not yet properly addressed. Plants that underwent insecticide treatment with HgCl(2) at the MAF Herbarium until the mid 1970s have persistent high concentrations of Hg in the range 1093-11,967 microg g(-1), whereas untreated specimens are in the range of 1.2-4.3 microg g(-1). The first group induces high concentrations of Hg (gas) in the main herbarium room, with seasonal variations of 404-727 ng m(-3) (late winter) and 748-7797 ng m(-3) (early summer) (baseline for Hg: 8 ng m(-3)). A test survey at another herbarium in Madrid showed even higher concentrations of Hg (gas) above 40,000 ng m(-3). The World Health Organization guidelines for chronic exposure to Hg (gas) are estimated at a maximum of 1000 ng m(-3). While staff was aware of the existence of HgCl(2) treated plants (the plant specimen sheets are labelled as 'poisoned'), they had no knowledge of the presence of high Hg (gas) concentrations in the buildings, a situation that may be relatively common in herbaria.