Fingerprinting and Groundwater Model Application to Evaluate Hydraulic Barrier Efficiency (Italy)

Remediation actions at contaminated sites are based on multiple numerical model scenarios considering different parameter distributions, source positions and contaminant transport paths. In some cases the excess of scenarios is due to uncertainties in the conceptual model as a result of the spread of contamination through heterogeneities in the physical system. Reduction of project hypotheses and conceptual model uncertainty is therefore needed. This result can be achieved by coupling hydrogeological investigations with environmental forensic techniques, better localization of the source and understanding of contamination history. In this respect, in the present study, compositional fingerprinting and groundwater flow modeling were applied to a former oil storage facility where, even though a hydraulic barrier had been built to stop the hydrocarbon plume, the presence of some hydrocarbons was still found in downgradient monitoring wells. The final aim was to evaluate the efficacy of the hydraulic barrier and identify of the source of pollution. Fingerprinting results indicated pollution with a gasoline-diesel mixture much altered by water washing and/or biodegradation. Comparison of seven groundwater samples collected in wells and monitoring wells was performed by analyzing the volatile fraction (BTEX) and the total ion chromatogram (TIC), focusing attention on: n-alkanes (m/z 85), alkylcyclohexanes (m/z 83), isoprenoids (m/z 113), C4-alkylbenzenes (m/z 134), C3-C6 alkylbenzenes and polycyclic aromatic hydrocarbons (PAHs). The most probable scenario was then identified by combining the results of fingerprinting with different contaminant paths obtained using the numerical model.     

The use of multilevel sampling techniques for determining shallow aquifer nitrate profiles

Nitrate is a worldwide pollutant in aquifers. Shallow aquifer nitrate concentrations generally display vertical stratification, with a maximum concentration immediately below the water level. The concentration then gradually decreases with depth. Different techniques can be used to highlight this stratification. The paper aims at comparing the advantages and limitations of three open hole multilevel sampling techniques (packer system, dialysis membrane samplers and bailer), chosen on the base of a literary review, to highlight a nitrate vertical stratification under the assumption of (sub)horizontal flow in the aquifer. The sampling systems were employed at three different times of the year in a shallow aquifer piezometer in northern Italy. The optimal purge time, equilibration time and water volume losses during the time in the piezometer were evaluated. Multilevel techniques highlighted a similar vertical nitrate stratification, present throughout the year. Indeed, nitrate concentrations generally decreased with depth downwards, but with significantly different levels in the sampling campaigns. Moreover, the sampling techniques produced different degrees of accuracy. More specifically, the dialysis membrane samplers provided the most accurate hydrochemical profile of the shallow aquifer and they appear to be necessary when the objective is to detect the discontinuities in the nitrate profile. Bailer and packer system showed the same nitrate profile with little differences of concentration. However, the bailer resulted much more easier to use.

     

Investigation of ZnO nanoparticles’ ecotoxicological effects towards different soil organisms

Introduction  

Nanomaterials have widespread applications in several industrial sectors. ZnO nanoparticles (NPs) are among the most commonly used metal oxide NPs in personal care products, coating and paints. However, their potential toxicological impact on the environment is largely unexplored.     

A system dynamics perspective on a viable systems approach definition for sustainable value

Aim of this work is to shed light on sustainable value and develop a model, based on vSa and translated at applicative level through the system dynamics methodology for measuring sustainable value. By adopting vSa perspective, value, characterized by strongly subjective contents, will be considered as a vector quantity, as the result of the subjective weighting of the different dimensions that may change according to the considered organization. Starting from the analysis of system dynamics and vSa, we will implement the theoretical framework into a model developed with system dynamics, hence through a methodology capable of addressing systemic problems which is also an expressive approach to solve issues arising in complex systems (characterized by interdependence, mutual interaction, information feedback, circular causality). In order to translate theory into “action and application” we will develop a model through which it will be possible to exploit the advantages of vSa implemented into an SD model, which ultimately can also be instantiated to specific cases and then simulated for further quantitative insights. Currently, there is no theoretical/practical approach to sustainable value measurement for business organizations that simultaneously considers the dimensions of the triple bottom line together with the subjective perspective of decision-makers. From these considerations, we derived the idea to integrate vSa and system dynamics with the aim of analyzing the issue of sustainable value, whose triple dimension is usually (erroneously) seen under a perspective that does not consider the interactions among those three dimensions. The integration of the subjective perspective within a model for calculating sustainable value can be seen as considering vSa as the theoretical framework, and system dynamics as the methodology that allows translating such an approach into a model that can later be simulated. It is also worth mentioning that through the application of the vSa theory to the case of sustainable value, by means of a transcoding approach like the system dynamics one, we are somehow trying to “redefine”, or better “enhance”, the vSa theory itself, by “operationalizing” it.     

Degrading permafrost river catchments and their impact on Arctic Ocean nearshore processes

Arctic warming is causing ancient perennially frozen ground (permafrost) to thaw, resulting in ground collapse, and reshaping of landscapes. This threatens Arctic peoples'' infrastructure, cultural sites, and land-based natural resources. Terrestrial permafrost thaw and ongoing intensification of hydrological cycles also enhance the amount and alter the type of organic carbon (OC) delivered from land to Arctic nearshore environments. These changes may affect coastal processes, food web dynamics and marine resources on which many traditional ways of life rely. Here, we examine how future projected increases in runoff and permafrost thaw from two permafrost-dominated Siberian watersheds—the Kolyma and Lena, may alter carbon turnover rates and OC distributions through river networks. We demonstrate that the unique composition of terrestrial permafrost-derived OC can cause significant increases to aquatic carbon degradation rates (20 to 60% faster rates with 1% permafrost OC). We compile results on aquatic OC degradation and examine how strengthening Arctic hydrological cycles may increase the connectivity between terrestrial landscapes and receiving nearshore ecosystems, with potential ramifications for coastal carbon budgets and ecosystem structure. To address the future challenges Arctic coastal communities will face, we argue that it will become essential to consider how nearshore ecosystems will respond to changing coastal inputs and identify how these may affect the resiliency and availability of essential food resources.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01666-z.     

Accumulation and metal fluxes in the central Venice Lagoon during the last century

Samples from 18 short sediment cores were analyzed for major and trace metals (Al, Fe, Ca, K, Mg, Mn, Si, Ti, Pb, Zn, Cu, Ni, and Cr), ²¹⁰Pb, ¹³⁷Cs, total organic carbon, grain size, and mineralogical composition to find the record of major environmental changes, either natural or anthropogenic, and to establish their chronologies. Some sediments are characterized by nearly constant composition over time, but others clearly show signs of an increasing marine influence, as an increase of the carbonate contents, after the opening of the Malamocco-Marghera Canal in 1969. These changes sometimes obscure the real pattern of pollutants and tracers, which is revealed by normalization against Al. Zn is the most important contaminant, with concentration factors up to 9.3 times the background level, and the most contaminated sediments are those within a few kilometers from the industrial district of Porto Marghera. ²¹⁰Pb activity-depth profiles were used to calculate apparent accumulation rates that provide a basis for the assessment of metal fluxes. The sediments of several sites show a significant increase in anthropogenic metal contamination starting from the second decade of last century, with maximum inputs from 1930 to 1970. The decrease of heavy metal concentrations observed in surficial sediments of some sampling sites could be related to a recent reduction of pollutant inputs.     

Comparison of pollination and defensive buzzes in bumblebees indicates species-specific and context-dependent vibrations

Bees produce vibrations in many contexts, including for defense and while foraging. Buzz pollination is a unique foraging behavior in which bees vibrate the anthers of flowers to eject pollen which is then collected and used as food. The relationships between buzzing properties and pollen release are well understood, but it is less clear to what extent buzzing vibrations vary among species, even though such information is crucial to understanding the functional relationships between bees and buzz-pollinated plants. Our goals in this study were (1) to examine whether pollination buzzes differ from those produced during defense, (2) to evaluate the similarity of buzzes between different species of bumblebees (Bombus spp.), and (3) to determine if body size affects the expression of buzzing properties. We found that relative peak amplitude, peak frequency, and duration were significantly different between species, but only relative peak amplitude differed between pollination and defensive buzzes. There were significant interactions between species and buzz type for peak frequency and duration, revealing that species differed in their patterns of expression in these buzz properties depending on the context. The only parameter affected by body size was duration, with larger bees producing shorter buzzes. Our findings suggest that although pollination and defensive buzzes differ in some properties, variability in buzz structure also exhibits a marked species-specific component. Species differences in pollination buzzes may have important implications for foraging preferences in bumblebees, especially if bees select flowers best matched to release pollen for their specific buzzing characteristics.