The use of trees for biomonitoring of mercury (Hg) and other atmospheric pollutants is of increasing importance today. Leaves from different species have been the most widely used plant organ for this purpose, but only pine bark, and not leaves, was used to monitor Hg pollution. In Almadén (South Central Spain), the largest cinnabar (HgS) deposits in the world have been mined for over 2000 years to obtain metallic Hg and this activity has caused the widespread dispersion of this toxic element in the local environment. A strip of pine trees, 2750 m in length, adjacent and to the South of the mining town has been studied in order to evaluate pine tree needles as monitors for Hg contamination in this heavily polluted area. The study involved the collection of pine tree leaves from several discrete sites along the strip, as well as samples from other nearby locations, together with soil samples and monitoring of atmospheric Hg in the area during both the day and night. Leaves and soils were analyzed for total Hg concentration by means of atomic absorption spectrometry; the leachable fraction of soil Hg was also analyzed by the CV-AFS technique. The results indicate that soils from the investigated area were not directly affected by mining related pollution, with low total Hg levels (3-280 mg kg) found in comparison with the nearby Almadén metallurgical precinct and very low leachable Hg contents (0.27-59.65 mg kg) were found. Moreover, pine tree needles have a low uptake capacity, with lower THg levels (0.03-6.68 mg kg) when compared to those of olive trees in Almadén. However, pine needles do show significant variability with regard to the distance from the source. Gaseous Hg exhibits a similar pattern, with higher levels close to the source, especially during night time (225 ng m). A multiple linear regression analysis (MLRA) revealed that gaseous Hg in the nocturnal period is the prime factor that influences the amount of Hg uptake by pine tree needles. This finding makes pine needles a promising candidate to biomonitor gaseous Hg on a local or regional scale worldwide. Almadén pine tree needles have been exposed to a number of different Hg sources, including the primary one, namely the old mine dump, and secondary sources such as polluted roads or illegal urban residual waste. The secondary sources cause some minor discrepancies in the model established by the MRLA. The biomonitoring capacity of pine needles needs to be evaluated in areas far from the source. The process involved in gaseous Hg uptake by pine needles appears more likely to involve sorption in the external part of the needle than uptake through stomas, thus making this process strongly dependent on high atmospheric Hg concentrations.

The geochemical data from surface soils are often neglected or questioned when prospecting for ore deposits within active mining districts due to the “background noise” produced by anthropogenic pollution derived from mining activity. Large datasets on a national and international scale offer interesting possibilities to discover prospective zones. In the present work, data from the Geochemical Atlas of Castilla–La Mancha were treated in an area with an intense history of mining Hg, Pb, Zn, and Sb: the Almadén and Guadalmez synclines and the Alcudia Valley. The sampling grid was densified to adapt it to the scale of the main geological formations, and a cluster analysis was carried out to establish the relationships between the variables and a factor analysis to distinguish between geogenic and metallogenic factors. The results showed very high concentrations of some elements of prospective interest in local background areas: Hg (51 mg kg−1), Pb (1190 mg kg−1), and Sb (45 mg kg−1), with high variation coefficients. Cluster analysis unveiled a relationship between most of the local ore-forming metals (As, Sb, Hg, Pb, and Ag) with a clear correlation between Hg and organic matter, suggesting a notable contribution of Hg in soil. The factor analysis highlighted five factors, three geogenic and two ore-forming elements. Despite Hg being the main candidate to form a separate factor, its aerial deposition and a large number of outliers in the Almadén syncline contributed to integrating the element into a geogenic factor. Instead, factors F4 (Pb and Zn) and F5 (As and Sb) delimited the prospective areas in both synclines far from the known and the exploited mines. Some of these areas coincided with discovered mineralized zones, specifically in the area SE of a derelict Sb mine, confirming the usefulness of these datasets and statistical tools in areas with recent mining activity.

Sulfide mining wastes may lead to severe environmental and human health risks. This study aims to use geochemical and ecotoxicological indicators for the assessment of the ecological risks of potentially toxic elements (PTEs) in the San Quintín mining group to categorize wastes prior to mining restoration. Ecotoxicity was evaluated using crustacean (Dahpnia magna, Thamnocephalus platyurus) and algae (Raphidocelis subcapitata) bioassays. The geochemical and mineralogical results suggested that the mining residues underwent intense weathering processes, with active processes of acidity generation and metal mobility. Total PTEs concentrations indicated that the mining materials were extremely polluted, with Pb, Zn and Cd geoaccumulation index (Igeo) values higher than 5 in more than 90% of the samples. The pollution load index (PLI) showed average values of 18.1, which classifies them as very highly polluted. The toxicity tests showed a higher toxicity for plants than crustaceans, being the highest values of toxicity related to toxic elements (Pb, Cd and Zn), electrical conductivity and to pH. This paper presents for the first time the combination of indices in the categorization of mining waste prior to its restoration. The combination of them has made it possible to categorize the waste and adapt the restoration and remediation procedures.

<p><strong>Abstract:</strong> The Remance gold mine, in Veraguas, Panama, has been widely affected by mining activity, whose last exploitation period was between 1989 and 1999, by the company Minera Remance S.A. Previous studies have reported that stream sediments are severely polluted; terrace sediments represented a serious ecological risk and stream sediments a high ecological risk represented by the presence of high concentrations of potentially toxic elements (PTEs. In addition, the study also showed that soil health, evaluated through the DHA (dehydrogenase activity) factor, is more affected in the terrace sediments and stream sediments than in the soils. The carcinogenic and non-carcinogenic risk assessment was exceeded for children into a recreational setting in areas of major mining activity; for adults, the carcinogenic risk is also exceeded mainly by the ingestion route. The area is inhabited by peasants, who carry out their daily activities, such as recreation and subsistence agriculture, reason why it is necessary to carry out bioaccessibility studies on these materials to properly assess the real risks for this population.</p> <p>The objective of this study has been to determine the oral bioaccessibility of PTEs in terrace sediments and stream sediments to evaluate the health risks that these materials represent in case of accidental ingestion in a recreational setting. The following PTEs were analysed: were determined in the pseudo-total fraction by ICP-OES: Cu, As, Zn, Sb and Ba. The oral bioaccessibility test was performed by the UBM method and the concentrations of the PTEs in the gastric and gastrointestinal phase were determined by ICP-OES. The percentage of bioaccessibility (% BAF) for the PTEs, and the carcinogenic and non-carcinogenic risks by ingestion in all fractions were evaluated for children and adults in a recreational setting.</p> <p>The results show that terrace sediments have higher total concentration of PTEs than stream sediments, while the oral bioaccessibility is higher in stream sediments than in terrace sediments and is higher in the gastric phase than in the gastrointestinal phase. The order of oral bioavailability was as follows: Cu>Zn>Ba>As>Sb.</p> <p>As for the non-carcinogenic risk by ingestion, the maximum permissible limit (HI=1) is exceeded for the sum of the studied PTEs in the pseudo-total fraction of stream sediments and terrace sediments in a recreational setting for children, but not in the gastric and gastrointestinal fractions. The maximum permissible limit for carcinogenic risk (1x10<sup>-5</sup>) is exceeded by As for adults and children in all stream and terrace sediments in the pseudototal fraction, and for children in the gastro and gastrointestinal fraction in the stream sediments of “El Toro” stream and terrace sediments of “Veneno” stream below one of the mine tailings accumulations. Therefore, recreational activity in these streams is not recommended.</p> <p><strong>Keywords</strong>: bioaccesibility, potentially toxic elements, ingestion, stream sediments, terrace sediments, gold mine, Panama</p>

<p>San Quintín is one of the derelict mines in Alcudia Valley Mining District, where large amounts of mining wastes have been disseminated during the last two centuries. These dumps and tailings materials are an important source of contamination of heavy metals and metalloids in the area. Nowadays, the restoration project for the abandoned mining area is beginning to be drafted, including a risk assessment of the wastes before restoration works. In this work, we carried out toxicity studies of these polluted materials, including data about total and soluble contain of As, Cd, Pb, Zn and Fe, mineralogical composition, and some bioassays to determine the toxicity effect of the samples to crustaceans (<em>D. magna</em> and <em>T. platyurus</em>) and algae (<em>R. subcapitata</em>). The pollution load index (PLI) has been calculated for each sample based on the pollution index (PI). Multielemental data and the indices calculated show that most of the samples present extremely high values of potentially toxic elements, and high values of contamination respect the background levels: 444 mg kg<sup>-1</sup> Cd, 144,900 mg kg<sup>-1</sup> Pb, 47,700 mg kg<sup>-1</sup> Zn, 202,600 mg kg<sup>-1</sup> Fe and 549 mg kg<sup>-1</sup> As. The bioassays suggest a relationship with pH, conductivity and grainsize. The EC<sub>50</sub> values were 458.7 to <2 of toxic units (TU) for <em>D. Magna</em> whereas for <em>T. Platyurus</em> the results oscillated between 2500 to <2. On the other hand, for algae organisms were 2083.3 to <2 TU. The studies carried out reveal the large accumulation of potentially toxic elements in mining waste and the risk they may pose to the associated ecosystems that develop in the area, as well as to human health.</p>