Spatially Explicit Analysis of Metal Transfer to Biota: Influence of Soil Contamination and Landscape

Concepts and developments for a new field in ecotoxicology, referred to as “landscape ecotoxicology,” were proposed in the 1990s; however, to date, few studies have been developed in this emergent field. In fact, there is a strong interest in developing this area, both for renewing the concepts and tools used in ecotoxicology as well as for responding to practical issues, such as risk assessment. The aim of this study was to investigate the spatial heterogeneity of metal bioaccumulation in animals in order to identify the role of spatially explicit factors, such as landscape as well as total and extractable metal concentrations in soils. Over a smelter-impacted area, we studied the accumulation of trace metals (TMs: Cd, Pb and Zn) in invertebrates (the grove snail Cepaea sp and the glass snail Oxychilus draparnaudi) and vertebrates (the bank vole Myodes glareolus and the greater white-toothed shrew Crocidura russula). Total and CaCl2-extractable concentrations of TMs were measured in soils from woody patches where the animals were captured. TM concentrations in animals exhibited a high spatial heterogeneity. They increased with soil pollution and were better explained by total rather than CaCl2-extractable TM concentrations, except in Cepaea sp. TM levels in animals and their variations along the pollution gradient were modulated by the landscape, and this influence was species and metal specific. Median soil metal concentrations (predicted by universal kriging) were calculated in buffers of increasing size and were related to bioaccumulation. The spatial scale at which TM concentrations in animals and soils showed the strongest correlations varied between metals, species and landscapes. The potential underlying mechanisms of landscape influence (community functioning, behaviour, etc.) are discussed. Present results highlight the need for the further development of landscape ecotoxicology and multi-scale approaches, which would enhance our understanding of pollutant transfer and effects in ecosystems

Sustaining the future through virtual worlds

Virtual worlds (VWs) continue to be used extensively in Australia and New Zealand higher education institutions although the tendency towards making unrealistic claims of efficacy and popularity appears to be over. Some educators at higher education institutions continue to use VWs in the same way as they have done in the past; others are exploring a range of different VWs or using them in new ways; whilst some are opting out altogether. This paper presents an overview of how 46 educators from some 26 institutions see VWs as an opportunity to sustain higher education. The positives and negatives of using VWs are discussed

Phosphorus sorption and availability in an andosol after a decade of organic or mineral fertilizer applications: Importance of pH and organic carbon modifications in soil as compared to phosphorus accumulation

The effect of organic fertilizers on soil phosphorus (P) availability is usually mainly associated with the rate and forms of P applied, while they also alter the soil physical-chemical properties, able to change P availability. We aimed to highlight the impact of pH and organic C modifications in soil on the inorganic P (Pi) sorption capacity and availability as compared to the effect of P accumulation after mineral or organic fertilizers. We conducted a 10-years-old field experiment on an andosol and compared fields that had been amended with mineral or organic (dairy slurry and manure compost) fertilizers against a non-fertilized control. Water and Olsen extractions and Pi sorption experiments were realized on soils sampled after 6 and 10 years of trial. We also realized an artificial and ex situ alkalization of the control soil to isolate the effect of pH on Pi sorption capacity. Organic fertilizer application increased total P, pH, and organic C in soil. Pi-Olsen increased mainly with soil total P (r2 adj = 0.79), while Pi-water increased jointly with soil total P and pH (r2 adj = 0.85). The Pi sorption capacity decreased with organic fertilizer application. Artificial and ex situ alkalization of the control soil showed that Pi sorption capacity decreased with increasing pH. Our study demonstrated that, beyond the P fertilization rate, the increase in organic C content and even more so in pH induced by a decade of organic fertilizer applications in soil decreased the Pi sorption capacity and consequently increased Pi-water in soil

Returning Organic Residues to Agricultural Land (RORAL) - Fuelling the Follow-the-Technology approach

International audienceRehabilitating disrupted nutrient cycles through organic residue recycling in agriculture may represent a win-win lever, particularly in urban-agricultural areas, with benefits at both ends of the food chain. It carries the promise of enhancing agriculture's eco-efficiency and resilience while reducing environmental pressure in urban and downstream areas. After several decades of largely unsatisfactory attempts to promote recycling practices through ad hoc transfer-of-technology approaches, this paper proposes an epistemological base for RURAL research. It represents a shift to a more modest `follow-the-technology' (Douthwaite et al., 2002) paradigm and implies that such research would benefit from being organized as a specific and coherent interdisciplinary research area. The way our research unit deals with these challenges is presented as an example. Starting from site-specific applied analytical research, an agro-environmental `plausible promise' is transformed to a system-level promise before being fed into a facilitated participatory integrated natural resource management (INRM) process. RURAL team members then participate as active stakeholders in this process. Intermediary INRM outcomes can give rise to new applied and basic research needs. A proof of concept case study involving implementation of the RURAL approach in Reunion is presented. This isolated territory with very limited natural resources, particularly arable land, and increasing demographic pressure represents one out of two types of high-potential areas. While showing how RURAL research is guided by site-specific knowledge gaps, this case study highlights how it also allows building up a capital of generic knowledge and skills in parallel. (C) 2013 Elsevier Ltd. All rights reserved

Procédés et traitements par compostage des effluents d'élevages

National audienceProcédés et traitements par compostage des effluents d'élevage