Antagonistic Cd and Zn isotope behavior in the extracted soil fractions from industrial areas.

The remobilization of metals accumulated in contaminated soils poses a threat to humans and ecosystems in general. Tracing metal fractionation provides valuable information for understanding the remobilization processes in smelting areas. Based on the difference between the isotopic system of Cd and Zn, this work aimed to couple isotope data and their leachability to identify possible remobilization processes in several soil types and land uses. For soil samples, the δ66/64Zn values ranged from 0.12 ± 0.05‰ to 0.28 ± 0.05‰ in Avilés (Spain) and from - 0.09 ± 0.05‰ to - 0.21 ± 0.05‰ in Príbram (Czech Republic), and the δ114/110Cd ranged from - 0.13 ± 0.05‰ to 0.01 ± 0.04‰ in Avilés and from - 0.86 ± 0.27‰ to - 0.24 ± 0.05‰ in Príbram. The metal fractions extracted using chemical extractions were always enriched in heavier Cd isotopes whilst Zn isotope systematics exhibited light or heavy enrichment according to the soil type and land uses. Coupling Zn and Cd systematics provided a tool for deciphering the mechanisms behind the remobilization processes: leaching of the anthropogenic materials and/or metal redistribution within the soil components prior to remobilization.

Multiple pollution sources unravelled by environmental forensics techniques and multivariate statistics.

Industrial sites affected by anthropogenic contamination, both past and present-day, commonly have intricate pollutant patterns, and source discrimination can be thus highly challenging. To this goal, this paper presents a novel approach combining multivariate statistics and environmental forensic techniques. The efficiency of this methodology was exemplified in a severely polluted estuarine area (Avilés, Spain), where factor analysis and clustering were performed to identify sub-areas with distinct geochemical behaviour. Once six clusters were defined and a pollution index applied, forensic tools revealed that the As speciation, Pb isotopes, and PAHs molecular ratios were useful to categorise the cluster groups on the basis of distinct pollution sources: Zn-smelting, coaly particles and waste disposal. Overall, this methodology offers valuable insight into pollution sources identification, which can be extended to comparable scenarios of complexly polluted environmental compartments. The information gathered using this approach is also important for the planning of risk assessment procedures and potential remediation strategies.

Effects of flooding on lead and cadmium speciation in sediments from a drinking water reservoir.

Rímov water reservoir on the river Malse is the main source of drinking water for the town of Ceské Budejovice and for the majority of inhabitants in the South Bohemian region, Czech Republic. Changes in cadmium and lead contents in bottom sediments before and after an extensive flood on the river Malse in August, 2002 were therefore determined. A five-step sequential extraction procedure was used in order to obtain more detailed information about the influence of the flood on heavy metal retention. In order to determine the mobility of lead and cadmium, the mobility factor (MF) for these heavy metals was calculated. The mobility factor of cadmium showed a significant decrease in the upper parts of the sediment profiles after the flood (e.g., from 59.4% to 49.1%) caused by a release of cadmium especially from the exchangeable fraction. There were no significant changes in the lead mobility factor after the flood, but a decrease of lead concentration in the exchangeable fraction was observed. Presented results show that the flood led to a leaching of the heavy metals present in bottom sediments into the environment.