Bioavailability in soils

The consumption of locally-produced vegetables by humans may be an important exposure pathway for soil contaminants in many urban settings and for agricultural land use. Hence, prediction of metal and metalloid uptake by vegetables from contaminated soils is an important part of the Human Health Risk Assessment procedure. The behaviour of metals (cadmium, chromium, cobalt, copper, mercury, molybdenum, nickel, lead and zinc) and metalloids (arsenic, boron and selenium) in contaminated soils depends to a large extent on the intrinsic charge, valence and speciation of the contaminant ion, and soil properties such as pH, redox status and contents of clay and/or organic matter. However, chemistry and behaviour of the contaminant in soil alone cannot predict soil-to-plant transfer. Root uptake, root selectivity, ion interactions, rhizosphere processes, leaf uptake from the atmosphere, and plant partitioning are important processes that ultimately govern the accumulation ofmetals and metalloids in edible vegetable tissues. Mechanistic models to accurately describe all these processes have not yet been developed, let alone validated under field conditions. Hence, to estimate risks by vegetable consumption, empirical models have been used to correlate concentrations of metals and metalloids in contaminated soils, soil physico-chemical characteristics, and concentrations of elements in vegetable tissues. These models should only be used within the bounds of their calibration, and often need to be re-calibrated or validated using local soil and environmental conditions on a regional or site-specific basis.Mike J. McLaughlin, Erik Smolders, Fien Degryse, and Rene Rietr

Trace metal budgets for forested catchments in Europe – Pb, Cd, Hg, Cu and Zn

Input/output budgets for cadmium (Cd), lead (Pb) and mercury (Hg) in the years 1997 monitored and determined for 14 small forest-covered catchments across Europe as part of the Integrated Monitoring program on the effects of long-range pollutants on ecosystems. Metal inputs were considered to derive from bulk deposition, throughfall and litterfall. Outputs were estimated from run-off values. Litterfall plus throughfall was taken as a measure of the total deposition of Pb and Hg (wet+dry) on the basis of evidence suggesting that, for these metals, internal circulation is negligible. The same is not true for Cd. Excluding a few sites with high discharge, between 74 and 94 % of the input Pb was retained within the catchments; significant Cd retention was also observed. High losses of Pb (>1.4 mgm (>0.15 mgm Central European sites with high water discharge. All other sites had outputs below or equal to 0.36 and 0.06 mgm Almost complete retention of Hg, 86 was reported in the Swedish sites. These high levels of metal retention were maintained even in the face of recent dramatic reductions in pollutant loads.–2011 were−2year−1) and Cd−2year−1) were observed in two mountainous−2year−1, respectively, for the two metals.–99 % of input

Examining Group Facilitation In Situ: The Use of Formulations in Facilitation Practice

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.In this paper we examine how the talk of the facilitator shapes group workshop interactions by using the conversational object 'formulation'. The data consist of video recordings of a corpus of four facilitated workshops held with management and development teams. By adopting an exploratory video-based investigation using conversational analysis to examine our data, we highlight the significance of three distinct set of formulations used by facilitators in workshops. Specifically, our findings show how formulations that encourage reflection or facilitate action, together with those collaboratively produced, enable sense making and the achievement of a temporal conversational order among participants. This research contributes to the study of facilitated workshops by offering a more nuanced approach to the understanding of the craftsmanship of doing facilitation, its effects on the workshop process and, ultimately, workshop outcomes