Showing papers by "Jean Louis Morel published in 2017"

Nickel drives bacterial community diversity in the rhizosphere of the hyperaccumulator Alyssum murale

Abstract: Ultramafic soils display high concentrations of nickel and a number of nutrient deficiencies. Nickel-hyperaccumulator plants, such as Alyssum murale , have evolved in these environments and developed specific metal homeostasis, showing concentrations of nickel (Ni) sometimes exceeding 1% in their aerial biomass. Rhizosphere bacterial communities associated with Ni-hyperaccumulator plants can differ from those of non-accumulating plants growing on the same site. Among the edaphic factors that could influence the phylogenetic structure of the bacterial communities, altitude and metal-bioavailability such as Ni in particular, could be significant. Our objectives were to understand the specific changes in the structure of the A. murale rhizosphere bacterial community that occurred across two gradients: elevation and Ni geochemistry, using a high-throughput sequencing technique (454-pyrosequencing). In this study, Chloroflexi was the major phylum present, with 53–77% of relative abundance. Moreover, we found that the higher the soil's chemically-available Ni contents, the higher was the relative abundance of Proteobacteria (particularly Alphaproteobacteria ) and Actinobacteria . In contrast, the abundance of Chloroflexi decreased with increasing levels of available Ni. Our results demonstrate that the chemical-availability of Ni in the studied soil drives the bacterial community diversity in the rhizosphere of A. murale, regardless of elevation gradient and other soil physicochemical parameters.

Agromining: Farming for Metals: Extracting Unconventional Resources Using Plants

Abstract: This is the first book on global agromining/phytomining technology. It presents the complete metal farming or agromining chain; an emerging technology expected to be transformative in the extraction of resources of those elements not accessible by traditional mining techniques. Meeting the demand for critical minerals (rare earth elements, platinum group elements, nickel cobalt) is increasingly difficult in the 21st century due to resource depletion and geopolitical factors. Agromining uses hyperaccumulator plants as “metal crops” farmed on sub-economic soils or mineral waste to obtain valuable elements.This book, which follows the metal farming chain, starts with the latest information on the global distribution and ecology of hyperaccumulator plants, biogeochemical pathways, the influence of rhizosphere microbes, as well as aspects of propagation and conservation of these unusual plants. It then presents the state of the art in new tools for identifying hyperaccumulator plants and for understanding their physiology and molecular biology. It goes on to describe the agronomy of “metal crops,” and opportunities for incorporating agromining into rehabilitation and mine closure, including test-cases of nickel, cobalt, selenium, thallium, rare earth elements and PGEs. Finally, it concludes with an overview of the latest developments in the processing of bio-ores and associated products.This book is edited and authored by the pioneers in the field who have been at the foreground of the development of agromining over the past three decades. It is timely as agromining is now at a pivotal point in its development with rapid expansion of activities in the field around the globe. As such it is of interest to environmental professionals in the minerals industry, government regulators and academics.

The accumulation and fractionation of Rare Earth Elements in hydroponically grown Phytolacca americana L.

Abstract: The widespread use of Rare Earth Elements (REEs) has resulted in localized soil pollution. Phytolacca americana L. has potential for REE phyto-extraction, but the related mechanism is not clear. In this study, the uptake and fractionation of REEs, and the influence of REEs on biomass production was investigated in hydroponically grown plants. Furthermore, the effects of Ca2+ and Al3+ on REE uptake, and the role of organic acids in REE translocation were also examined. Results showed that biomass and accumulation of REEs in P. americana were enhanced at low REE concentrations, but inhibited at higher concentrations in solution. Significant heavy REE (HREE) enrichment was observed during the stem-to-leaf transport, with a quotient of ∑LREE/∑HREE decreasing from 0.75 to 0.23. Ca2+ and Al3+ treatments diminished REE accumulation. The ∑LREE/∑HREE ratio decreased from 0.84 to 0.62 with increasing input of Ca2+, but increased from 0.83 to 0.92 with higher Al addition. LREEs appear to enter into the root of P. americana through Ca2+ ion channels, whereas HREEs may share pathways with Al3+. Finally, citrate plays an important role in the translocation of REEs in P. americana.

Decrease in the genotoxicity of metal-contaminated soils with biochar amendments

Abstract: Biochar amendments, i.e., the solid product of biomass pyrolysis, reduce soil metal availability, which may lower the toxicity of metal-contaminated soils. A direct link between the decrease in soil metal availability and improved plant development is however often difficult to establish, as biochar may induce undesirable side effects on plant growth, e.g., a modification to plant nutrition. In order to investigate toxicity processes at a cellular level, roots of Vicia faba were exposed for 7 days to three metal-contaminated substrates and one control soil, amended with a 0 or 5% (w/w) addition of a wood-derived biochar. Exposure to pure biochar was also tested. Root tip cells were then observed to count the number of micronuclei as an estimation of DNA damage and the number of cells at mitosis stage. Results showed that biochar amendments led to a significant decrease in soil metal availability (Cd, Cu, Ni, Pb, and Zn) and to enhance root development on acidic substrates. The micronucleus frequency in root tip cells was positively correlated and the number of mitotic cells negatively, to the extractability of Zn in soils and to the concentration of Zn in secondary roots. Exposure to pure biochar caused a lower production of roots than most soil substrates, but led to the lowest number of observed micronuclei. In conclusion, biochar amendments can reduce the genotoxicity associated with the presence of metallic contaminants in soils, thereby potentially improving plant growth.

Soils within cities. Global approaches to their sustainable management - composition, properties, and functions of soils of the urban environment

Abstract: Soils Within Cities: Global Approaches to Their Sustainable Management—Composition, Properties, and Functions of Soils of the Urban Environment T he book Soils within Cities, edited by M. J. Levin, K.-H. J. Kim, J. L. Morel, W. Burghardt, P. Charzyński, and R. K. Shaw, is a compendium of relatively short chapters with an introduction and history of the SUITMAWorking Group that was launched at the 16th World Congress of the International Union of Soil Science in 1998. Collectively, the book's authors come from the SUITMAWorking Group, and as a result the book reads more like proceedings for a SUITMA conference, which have been held biennially since 2000, than as an edited book. It is important to note that SUITMA is an acronym for Soils of Urban, Industrial, Traffic, Mining and Military areas, which makes this volume a more expansive view of urban soils than has typically been presented in earlier books published on the subject. In addition, an essential value of SUITMA (and this book) is that it encompasses an international perspective on urban soil research. The book is basically organized around three major topics: (1) characteristics, formation, classification, and survey (Chapters 2, 3, 4, and 5); (2) management (Chapters 6 and 7); and (3) ecosystem services provided by urban soils (Chapters 8 and 9). Each topic has a number of relatively short subchapters that are loosely related to the overall chapter, but do not follow a common format or writing style. Therefore, on the one hand, the reader will have to get past the varying styles of writing, formatting, and so on, but on the other hand, there is a wealth of information and insight about urban soils with varying perspectives from around the world. I found the first and third major topics to be the most compelling and informative. There have been great strides in developing classification systems for urban soils and their survey andmapping, which is clearly a success story for urban soil science and its application. It would, however, behoove the discipline to put urban soils within the context of overall anthropogenic effects, such as with cultivation and other land uses. More also could have been made of the “novelty” of urban environments and the assemblages of species that occur in urban areas with respect to soil formation, biodiversity, and ecosystem processes, for instance, the notion that urban ecosystems are “emergent” and thus can serve as “natural experiments” to study soil responses to the effects of invasive plant and animal species or as analogs to assess the impacts of climate change on soil processes. In addition, from a practical standpoint, no mention is made of the interpretation of soil types or mapping units being described in urban landscapes. But these are only minor criticisms, given the relatively recent emergence of urban soil science and SUITMA in the previous two decades. This compendium of chapters represents the most thorough overview of urban soils yet found in a single volume, and I congratulate the editors for their efforts to publish this book. More specific comments of the three major topics follow. Chapter 2 is the longest of all the chapters in the total number of pages and is made up of several subchapters. Together these subchapters cover the characteristics, criteria, and functioning of urban soils. Accordingly, this chapter provides the bases for discussing SUITMA soils in the remainder of the book. Subchapter 2.2 in particular provides a nice overview of anthropogenic soil criteria, which again is mostly directed at urban soil conditions and not necessarily inclusive of other types of anthropogenic influences on soil characteristics, such as with cultivated soils. In particular, the authors make a good case for recognizing human-altered and human-transported materials to capture soil modifications in urban landscapes and how human-altered and human-transported materials can be recognized