miércoles, 7 de febrero de 2018

Spatial gradient of human health risk from exposure to trace elements and radioactive pollutants in soils at the Puchuncaví-Ventanas industrial complex, Chile

The Punchuncaví Valley in central Chile, heavily affected by a range of anthropogenic emissions from a localized industrial complex, has been studied as a model environment for evaluating the spatial gradient of human health risk, which is mainly caused by trace elemental pollutants in soil. Soil elemental profiles in 121 samples from five selected locations representing different degrees of impact from the industrial source were used for human risk estimation. Distance to source dependent cumulative non-carcinogenic hazard indexes above 1 for children (max 4.4 – min 1.5) was found in the study area, ingestion being the most relevant risk pathway. The significance of health risk differences within the study area was confirmed by statistical analysis (ANOVA and HCA) of individual hazard index values at the five sampling locations. As was the dominant factor causing unacceptable carcinogenic risk levels for children (<10−4) at the two sampling locations which are closer to the industrial complex, whereas the risk was just in the tolerable range (10−6 – 10−4) for children and adults in the rest of the sampling locations at the study area. Furthermore, we assessed gamma-ray radiation external hazard indexes and annual effective dose rate from the natural radioactivity elements (226Ra, 232Th and 40K) levels in the surface soils of the study area. The highest average values for the specific activity of 232Th (31 Bq kg−1), 40K (615 Bq kg− 1), and 226Ra (25 Bq kg−1) are lower than limit recommended by OECD, so no significant radioactive risk was detected within the study area. In addition, no significant variability of radioactive risk was observed among sampling locations. Read more

martes, 4 de octubre de 2016

Antimony speciation in soils, sediments and volcanic ashes by microwave extraction and HPLC-HG-AFS detection

On the 5th of May 2008, the first recorded eruption of the Chaitén Volcano in southern Chile occurred. Because one of the main natural sources of Sb is volcanic activity, it was necessary to study the distribution of Sb and its species in the nearby ecosystem. The present study aims to develop a methodology for total Sb determination by ICP-MS and a method for Sb(V) and Sb(III) determination by HPLC-HG-AFS in soils, sediments and volcanic ash.
Chaiten eruption, Xinhua Photo
Microwave digestion in a 6 mL HNO3 and 0.5 mL HBF4 acid digestion mixture can achieve total solubilization of Sb in solid samples. Thirty minutes at 200 °C with 100 mmol L− 1 of oxalic acid were suitable conditions for fast and efficient microwave extraction to obtain a good extraction yield. However, Sb(III) stabilization was strongly inhibited; thus, the mixture of 100 mmol L− 1 + 20 mmol L− 1 of ascorbic acid was the best for Sb solubilization and Sb(III) stabilization. A total of 1.8 ± 0.1 μg g− 1 of Sb was quantified in the volcanic ash from the first eruption. The Sb concentrations in the sediments were 3 times higher than the Sb concentrations in the sediments from the reference zone. In the extracts of the volcanic ash and sediment, Sb(III) was the most abundant species, accounting for 70 to 97% of the total Sb found in the extracts. The results suggest that most of the Sb thrown from the Chaitén Volcano accumulated in the sediments at the mouths of the Yelcho and Chaitén Rivers, mainly in the form of Sb(III). Read more

martes, 5 de julio de 2016

A semiautomatic system for soluble lead and copper monitoring in atmospheric deposition by coupling of passive elemental fractionation sampling and voltammetric measurement on screen printed gold electrodes

We propose here the concept of semiautomatic measurement of soluble copper and lead in atmospheric deposition by the coupling of filtrating-bulk passive sampling by an atmospheric elemental fractionation sampler (AEFS) designed for fractionation of soluble and insoluble elemental species, and square wave anodic stripping voltammetric detection on screen printed electrodes. The voltammetric parameters were optimized to provide a reliable method for Pb(II) and Cu(II)monitoring with detection limits in the low ng mL−1 range. The method was validated
by analyzing ambient water certified referencematerials with good agreement between measured and certified values. The monitoring system was tested during a 1 month experimental campaign in a suburban area and proved useful to monitor copper changes in the atmospheric deposition. Leadwas alsomeasurable after fortification since its levels were under the detection limit of the voltammetric method. The results obtained were contrasted by a lab based standard ICP-MS method with good correlation.Our results are promising about the possibility of routine field use of unattended
voltammetric measurements of trace element monitoring in atmospheric deposition. Published in Microchemical Journal, 2016. Read more

martes, 21 de junio de 2016

Temporal and spatial variation of trace elements in atmospheric deposition around the industrial area of Puchuncaví-Ventanas (Chile) and its influence on exceedances of lead and cadmium critical loads in soils

Fractionation of elemental contents in atmospheric samples is useful to evaluate pollution levels for risk assessment and pollution sources assignment. We present here the main results of long-term characterization of atmospheric deposition by using a recently developed atmospheric elemental fractionation sampler (AEFS) for major and trace elements monitoring around an important industrial complex located in Puchuncaví region (Chile). Atmospheric deposition samples were collected during two sampling campaigns (2010 and 2011) at four sampling locations: La Greda (LG), Los Maitenes (LM), Puchuncaví (PU) and Valle Alegre (VA). Sample digestion and ICP-MS gave elements deposition values (Al, As, Ba, Cd, Co, Cu, Fe, K, Mn, Pb, Sb, Ti, V and Zn) in the insoluble fraction of the total atmospheric deposition. Results showed that LG location, the closest location to the industrial complex, was the more polluted sampling site having the highest values for the analyzed elements. PU and LM were the next more polluted and, finally, the lowest elements concentrations were registered at VA. The application of Principal Component Analysis and Cluster Analysis identified industrial, traffic and mineral-crustal factors. We found critical loads exceedances for Pb at all sampling locations in the area affected by the industrial emissions, more significant in LG close to the industrial complex, with a trend to decrease in 2011, whereas no exceedances due to atmospheric deposition were detected for Cd. Paper published in Chemosphere. Read more

martes, 31 de mayo de 2016

Long-term assessment of ecological risk from deposition of elemental pollutants in the vicinity of the industrial area of Puchuncaví-Ventanas, central Chile

The present work investigates soil pollution by elemental contaminants and compares ecological risk indexes related to industrial activities for the case study of Puchuncaví-Ventanas: a relevant industrial zone located in central Chile. Selected elements (As, Pb, Cd, Ni, Hg, V, Mn, Zn, Sr, Sb, Cr, Co, Cu, K, and Ba) were analyzed during a long-term period (yearly sampling campaigns during 2007–2011), at 5 sampling stations representing different degrees of impact. PCA and cluster analysis allowed identifying a copper smelter and a coal-fired power plant complex asmajor pollution sources. Geoaccumulation index (Igeo), enrichment factor (EF), contamination factor (Cf), contamination degree (Cdeg), and integrated pollution index (IPI) are critically discussed for quantitative ecological risk assessment. Igeo, EFandCf indexes are producing comparable environmental information, showing moderate to high pollution risks in the area that demands furthermonitoring and adoption of prevention and remediation measures. Published in Science of the Total Environment. Read more

martes, 17 de mayo de 2016

Ambient air levels and health risk assessment of benzo(a)pyrene in atmospheric particulate matter samples from low polluted areas: application of an optimized microwave extraction and HPLC-FL methodology

A new methodology involving a simple and fast pretreatment of the samples by microwave-assisted extraction and concentration by N2 stream, followed by HPLC with fluorescence detection, was used for determining the concentration of benzo(a)pyrene (BaP) in atmospheric particulate matter (PM10 fraction). Obtained LOD, 1.0 × 10−3 ng/m3, was adequate for the analysis of benzo(a)pyrene in the samples, and BaP recovery from PAH in Fine Dust (PM10-like) certified reference material was nearly quantitative (86 %). The validated procedure was applied for analyzing 115 PM10 samples collected at different sampling locations in the low-polluted area of Extremadura (Southwest Spain) during a monitoring campaign carried out in 2011–2012. BaP spatial variations and seasonal variability were investigated as well as the influence of meteorological conditions and different air pollutants concentrations. A normalized protocol for health risk assessment was applied to estimate lifetime cancer risk due to BaP inhalation in the sampling areas, finding that around eight inhabitants per million people may develop lung cancer due to the exposition to BaP in atmospheric particulates emitted by the investigated sources. Published in Environmental Science and Pollution Research. Read more

jueves, 28 de abril de 2016

Mercury pollution assessment in soils affected by industrial emissions using miniaturized ultrasonic probe extraction and ICP-MS

A combination of probe ultrasonic extraction, optimized by surface response methodology, and Inductively coupled plasma mass spectrometry (ICP-MS) detection is described in this work as an effective methodology  for mercury monitoring in soils affected by industrial emissions. Minute amounts of samples (typically
20 mg) can be extracted in 3 min by 1 mL of HCl-based extracting solution, without risk of mercury losses, and sub sequentially assayed by ICP-MS. The method was successfully tested on soil standard reference materials and then applied to mercury monitoring in a large set of real soil samples collected during a long-term monitoring survey (2007–2011) around the industrial area of Puchuncaví, Chile. The method proved to be useful for investigation of spatial and temporal mercury variability in the area, showing an intermediate to high mercury contamination with potential impact on the surrounding ecosystem. Published in the International Journal of Environmental Science and Technology.  Read more