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In the present study, we assessed the non-carcinogenic and carcinogenic human health risk due to exposure to trace elements in soil and indoor dust in Puchuncaví valley. We also determined the associations between trace element concentration in hair/toenails and the estimated chronic daily intake of trace elements in soil and indoor dust. We found statistically significant association between the trace element concentration in hair/toenails and the estimated chronic daily intake of soil and indoor dust. Indoor dust was more important than soil in terms of human exposure to trace elements in Puchuncaví, due to the high concentration of trace elements on this environmental media and long periods of time that the population spends at their households. With regards to non-carcinogenic risk, we found that there was no health risk associated to soil and indoor dust exposure in the Puchuncaví valley, because none of the hazard quotient values surpassed 1.0. However, carcinogenic risk due to arsenic exposure was above the threshold value of 1.0E-04 in the population of young children (from 1 to 5 years old) in all studied areas, including the control, and in the population of children (from 6 to <18 years old) in the exposed area. Such risk values are classified as unacceptable (US EPA, 2001), requiring some target intervention from the Chilean government. [ABSTRACT FROM AUTHOR]

Purpose: Arid and hyper-arid zones worldwide are reservoirs of chemical compounds, among them are various trace elements. With climate change, abnormal precipitation is occurring in arid and hyper-arid mountainous zones, which in turn is increasing the displacement of trace elements from mountainous to populated areas. The objective of this study was to evaluate trace element displacement of a sediment-laden flood in the Copiapó River Basin on March 24-25, 2015. Materials and methods: Sixty topsoil samples were taken from 20 agricultural fields. Soil organic matter content, pH, electrical conductivity, and particle size were determined according to accepted procedures in Chile. Samples were acid-digested to determine total Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Se, and Zn content by flame atomic absorption spectroscopy. Hydride generation AAS was used for As and Se determination, and Hg was quantified by cold vapor AAS. Detection limits were 0.2, 0.05, 0.1, and 5.0 mg kg for Cd, Hg, Se, and Mo, respectively. Correlation and principal component analyses were made, and theoretical distribution functions were fitted to each element. Results and discussion: Metal concentration showed a strong correlation between SOM and particle size, explaining the first component from the principal component analysis. All trace elements correlated well between each other except for Mo and Se. Mo values were consistently below detection levels (<5.0 mg kg). Expected values for the elements were (95% of probability): 13-37 g Al kg, 10-50 mg As kg, <0.2-0.6 mg Cd kg, 13-25 mg Cr kg, 27-281 mg Cu kg, 27-40 g Fe kg, <0.05-6.5 mg Hg kg, 516-1.080 mg Mn kg, 7-24 mg Ni kg, 13-50 mg Pb kg, 0.2-0.6 mg Se kg, and 61-172 mg Zn kg. Concentrations of As, Cu, and Hg were consistently above national standards. Conclusions: The authors conclude that the trace element contents in sediments deposited by the event are within expected values based on soil data in Chile. [ABSTRACT FROM AUTHOR]

Metal contents in soil samples are commonly used to evaluate contamination levels. However, the distribution of metals is dependent on particle size. We investigated the distribution of metals in various particle size fractions of the soil from four sites of the Puchuncaví Valley (Central Chile). The soil samples were segregated into size fractions ranging from 0.3 to 20 μm and analyzed using inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). The results of the statistical analysis of the total metal concentrations indicated that the soil samples from Greda and Maitenes, the sites nearest the industrial sources, are the most contaminated. For these sites, the size-fractionated samples containing higher concentrations of Cu, Zn, As, and Pb were found in the finer fractions, suggesting anthropogenic depositions from smelter facilities. In addition, a high Ca concentration was observed in the finer fractions, which could be attributed to the technological approaches used to reduce the SO2 emissions from the roasting process of copper sulfide. The mineral composition of fine particles permitted the identification of Tenorite and Calcium oxide, which are most likely associated with smelting activities, confirming emission of enriched particulate matter from the copper smelter. [ABSTRACT FROM AUTHOR]

Abstract: The Puchuncaví Valley in central Chile has been exposed to atmospheric depositions from a copper smelter. Nowadays, soils in the surrounding area are acidic and contaminated with Cu and As. The objective of this study was to determine the effectiveness of lime and compost for in situ immobilization of trace elements in the soils of the Puchuncaví Valley by using earthworms as bioindicators of toxicity. The lime and compost treatments significantly increased soil pH and decreased the soluble and exchangeable Zn, exchangeable Cu, and free Cu2+ activity. However, the compost treatment increased soluble Cu, and soluble and exchangeable As. Lime application had no effect on earthworm reproduction in comparison with the unamended control, whereas the application of compost increased cocoon and juvenile production. There was a spatial variability of soil properties within treatments in the field plots. This allowed the identification of which soil properties were actually having an impact on earthworm reproduction. For both cocoon and juvenile production, soil organic matter (SOM) was a positive factor, i.e., more SOM increased cocoon or juvenile production. The toxicity (negative) factor was total soil As. However, total Cu and total As were well correlated (R 2=0.80, p<0.001), hence some of the trends could have been masked. In summary, compost treatment was effective in improving the quality of soils of Puchuncaví Valley, increasing earthworm reproduction. Future Chilean legislation on maximum permissible concentrations of trace elements in soils should consider SOM content due to its effect on trace element solubility and bioavailability. [Copyright &y& Elsevier]

Abstract: We studied soils exposed to emissions from the Ventanas copper smelter in central Chile. Values of pH, free Cu2+ activity, and total dissolved copper were determined in the saturated paste extracts and the soil solutions collected by means of perforated plastic bottles installed in situ. Soil solutions were collected based on the periodicity of the rain. The topsoils (up to 30 cm) exhibited pH values in the saturated paste extracts of 4.6–5.5 and total soil copper concentrations of 310–640 mg/kg. In contrast, subsoils exhibited pH values in the saturated paste extracts of 6.4–7.2 and total soil copper concentrations of 30–60 mg/kg. These data suggest that the anthropogenic inputs of the Ventanas smelter, with respect to increase in Cu concentrations and acidification, are restricted to the topsoil while the subsoil remains unaffected. The above observations are probably due to sandy loam texture of the topsoils that allowed rapid water infiltration that did not allow the equilibrium between the rain water and the soil constituents to be reached. Consistent with this argument, soil solutions were not as acid as saturated paste extracts. Likewise, free Cu2+ activities and total dissolved copper concentrations in the soil solutions were lower in the saturated paste extracts. Thus, saturated paste extracts were not a good proxy of soil solutions for short-duration and intense rain events. In situ soil solution sampling by simple and low-cost devices, such as perforated plastic bottles used in this study, is a better mean for assessment of metal mobility in contaminated soils than saturated paste extracts. In solutions percolating through the soil during rain events, dissolved organic carbon was the major factor controlling total dissolved copper concentrations while soil pH was the major factor controlling the free Cu2+ activity. [Copyright &y& Elsevier]

In the area surrounding the El Teniente giant porphyry copper deposit, eight soil sites were sampled at three depth levels in the summer 2004. The sites were selected for their theoretical potential of being influenced by past SO2 emissions from the smelter and/or seepage from a now idle tailings impoundment. The soil mineralogy, grain size distribution, total organic matter contents, major element composition, cation exchange capacity, and Cu, Mo, Pb, Zn, As and SO4 2− concentrations were determined for all samples after nitric acid extraction and separate leaches by ammonium acetate (pH 7) and sodium acetate (pH 5). For water rinses, only Cu could be determined with the analytical set-up used. Cu and SO4 2− enrichment in topsoils was found at six sites either downwind from the smelter or within the combined influence of the smelter and the tailings impoundment. Both elements were released partially by ammonium and sodium acetate extractions. Due to the scarce background trace element concentrations of soil and rock outside the immediate mine area, assessment of trace element mobility for Mo, Zn, Pb and As was difficult. Arsenic was found to be concentrated in soil horizons with high smectite and/or organic matter contents. Mo appears to be linked to the presence of windblown tailings sediment in the soils. Mobilization of Mo, Zn, and As for the acetate extractions was minimal or below the detection limits for the AAS technique used. The presence of windblown tailings is considered to be an additional impact on the soils in the foothills of the El Teniente compound, together with the potential of acidity surges and Cu mobilization in topsoils after rainfalls. Two sites located at the western limit of the former SO2 saturated zone with strongly zeolitized soils and underlying rock did not show any Cu or SO4 2− enrichment in the topsoils, and remaining total trace element concentrations were below the known regional background levels. [ABSTRACT FROM AUTHOR]