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 are 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) were 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.

Miniaturized voltammetric stripping on screen printed gold electrodes for field determination of copper in atmospheric deposition.

The applicability of commercial screen-printed gold electrodes (SPGEs) connected to a portable potentiostat and a laptop has been explored to optimize a new square wave anodic stripping voltammetric method for on-site determination of soluble Cu(II) in atmospheric deposition samples taken around an industrial complex. Electrode conditioning procedures, chemical and instrumental variables have been optimized to develop a reliable method capable of measuring dissolved copper with a detection limit of 3.7 ng mL(-1), useful for pollution monitoring or screening purposes. The proposed method was tested with the SLRS-5 River Water for Trace Metals (recoveries 109.9-113.1%) and the SPS-SW2 Batch 121 Elements in Surface Waters (recoveries 93.2-97.6%). The method was applied to soluble Cu(II) measurement in liquid samples taken by a total atmospheric deposition collector modified with a quartz filter for soluble and insoluble elemental speciation. The voltammetric measurements on field samples were tested in the lab by a reference ICP-MS method, with good agreement. The proposed method proved capability for field operation during a two weeks monitoring campaign.

Determination of mercury in indoor dust samples by ultrasonic probe microextraction and stripping voltammetry on gold nanoparticles-modified screen-printed electrodes.

A miniaturized, fast, and efficient ultrasonic probe assisted method for Hg(II) extraction from indoor dust samples, in hydrochloric acid medium, was developed. The combination of the extraction method with the electrochemical determination of mercury by square-wave anodic stripping voltammetry (SWASV) on gold nanoparticles-modified screen-printed carbon electrodes (AuNPs-SPCEs) resulted in a convenient method for rapid, sensitive, and reliable mercury monitoring. Parameters involved in the extraction such as acid concentration, sonication amplitude, and sonication time were optimized using a Face-centered cube Central Composite Design. ICP-MS was also used to contrast the methodology and good agreement with electrochemical results was verified. Optimization and validation of the procedure were carried out by using NIST Standard Reference Material(®) 2583 Trace Elements in Indoor Dust. Finally, the proposed methodology was successfully applied for Hg(II) determination in dust samples collected at different indoor ambients.

Determination of mercury in ambient water samples by anodic stripping voltammetry on screen-printed gold electrodes.

The applicability of commercial screen-printed gold electrodes (SPGEs) for the determination of Hg(II) in ambient water samples by square wave anodic stripping voltammetry has been demonstrated. Electrode conditioning procedures, chemical and instrumental variables have been optimized to develop a reliable method capable of measuring dissolved mercury in the low ng mL(-1) range (detection limit 1.1 ng mL(-1)), useful for pollution monitoring or screening purposes. The proposed method was tested with the NIST 1641d Mercury in Water Standard Reference Material (recoveries 90.0-110%) and the NCS ZC 76303 Mercury in Water Certified Reference Material (recoveries 82.5-90.6%). Waste water samples from industrial origin and fortified rain water samples were assayed for mercury by the proposed method and by a reference ICP-MS method, with good agreement. Screen printing technology thus opens a useful way for the construction of reliable electrochemical sensors for decentralized or even field Hg(II) testing.