Growing lignocellulosic crops on marginal lands could compose a substantial proportion of future energy resources. The potential of poplar was explored, by devising a field trial of two hectares in ...2007 in a metal-contaminated site to quantify the genotypic variation in the growth traits of 14 poplar genotypes grown in short-rotation coppice and to assess element transfer and export by individual genotypes. Our data led us to conclusions about the genotypic variations in poplar growth on a moderately contaminated site, with the Vesten genotype being the most productive. This genotype also accumulated the least amounts of trace elements, whereas the Trichobel genotype accumulated up to 170 mg Zn kg−1 DW in the branches, with large variation being exhibited among the genotypes for trace element (TE) accumulation. Soil element depletion occurred for a range of TEs, whereas the soil content of major nutrients and the pH remained unchanged or slightly increased after 10 years of poplar growth. The higher TE content of bark tissues compared with the wood and the higher proportion of bark in branches compared with the wood led us to recommend that only stem wood be harvested, instead of the whole tree, which will enable a reduction in the risks encountered with TE-enriched biomass in the valorization process.
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•We observed genotypic variations in growth of poplar at a moderately contaminated site.•There were large variations between genotypes for trace element accumulation.•Soil depletion occurred for a range of trace element after 10 years of growth.•Branches had accumulated a lot more elements than wood.•We recommend choosing stemwood-only harvesting instead of whole-tree harvesting.
The use of fast growing trees is a common practice for phytoremediation of contaminated soils. Plant roots can change trace element bioavailability in soils. We studied the effect of Populus alba on ...trace element bioavailability on two contaminated soils (one with neutral pH and other with acid pH) comparing two methods (0.01M CaCl2-extractable in soil and concentration in soil pore water SPW), trace element accumulation in leaves and plant development over 36months. Results were compared to those obtained with a non-contaminated soil. The experiment was carried out in containers (95L of volume and 1m height). Half of the containers for each soil were planted with P. alba saplings and the others remained without plant. In neutral soils plant growth did not influence soil pH; the greatest effect due to plant growth was found in acid soil. Values of pH obtained by SPW showed a similar trend compared to those obtained after soil KCl extraction. Bioavailability of trace elements determined by both methods followed the same behavior in the three studied soils. Both methods for determining trace element bioavailability in soil were accurate to predict plant uptake. In non-contaminated soil, plants tended to increase micronutrients (Cu, Mn and Zn) availability. However, in case of contaminated soil, the growth of P. alba did not increase trace element availability. Moreover, results on height and diameter of the trunk of the trees, during 36months, demonstrated that the presence of total trace elements in soil did not affect plant development.
•Populus alba in contaminated soils provide benefits: soil restoration and biomass production.•CaCl2 extraction and SPW analysis were accurate to predict trace element bioavailability.•An effect on pH due to plant growth was found in acid soil.•The growth of P. alba did not increase trace element availability in contaminated soil.•The selected soil contamination did not affect plant development.
•The presence of root system in soils improves readily soluble C and N.•Populus alba is an option to remediate trace element contaminated soils.•Soil remediation can be monitored through specific ...biomarkers (enzyme test and MBC).•Poplar growth is an effective option to reduce acidity in soils.
Certain plant species have the ability to grow in trace element-polluted soils without showing any negative symptoms. These species could be considered for phytoremediation techniques and their presence might influence the abundance, activity and composition of soil microbial communities. In this work we investigated the root-induced changes in chemical (pH, soluble trace element concentrations, total organic C, water-soluble C, and nitrogen concentrations) and biochemical (microbial biomass C, β-glucosidase activity and protease activity) properties caused by Populus alba on two contaminated soils (one with neutral pH (AZ) and other with acid pH (DO)) for a period of over 36 months. The results were compared to those obtained with a non-contaminated soil. The experiment was carried out in containers. At the end of the experiment, samples of the soil directly adhered to the root and that located more than 5cm from the root were also studied. The results showed that, in neutral soils, poplar did not influence soil pH; the greatest effect on pH due to plant growth was found in acid soil. Poplar presence increased C sources, through root exudates, in all soils. In AZ soil, poplar maintained chemical and biochemical properties, whereas an important decrease in soil quality was observed in the same bare soils. The effect of poplar development on soil quality was even more appreciable in acid contaminated soil (DO), in which the tree also produced a strong increment of soil pH, a decrease in trace element concentrations and an improvement of chemical and biochemical properties. We concluded that P. alba is a suitable plant for the phytoremediation of trace element contaminated soils. Moreover, root exudates of this species may be responsible for the improvement of soil quality in trace element contaminated soils.
•The inoculation treatment did not influence the overall poplar structure.•The Skado cultivar produced more biomass than the I214 cultivar at both sites.•The I214 clone suffered more from climatic ...conditions than Skado clone.•The mycorrhizal inoculation improved the Skado biomass production at both sites.•The field inoculation led to significantly enhanced plant performance.
Afforestation of trace element (TE)-contaminated soil, notably with fast growing trees producing large biomass has been demonstrated to be an attractive option for their bioremediation. Mycorrhizal fungi can form symbiotic associations with plants, contributing to TE tolerance and participating actively in bioremediation processes. We studied the effects of mycorrhizal inoculation on the growth of two poplar clones (Skado and I214), to large-scale. Two TE-contaminated sites of ca. 1ha (Pierrelaye and Fresnes-sur-Escaut, France) were planted with 2200 trees, and were either inoculated with a mixed commercial inoculum or not-inoculated and allometric parameters were determined after 2 and 4 years of growth. The height diameter relationships remained linear overtime, although the second period of the experiment has been more favorable to growth of the Skado clone and its survival rates were higher compared than those of the I214 clone, at both sites. The inoculation with mycorrhizal significantly impacted the biomass production of the Skado clone at both sites, despite striking differences in soil structure and contamination. In overall, this bioaugmentation option with mycorrhizal fungi influenced more poplar growth than soil contamination and highly improved its biomass production.
Revegetation of industrial landfills and mine tailing may restore key soil functions and reduce the environmental impacts of contaminants. These marginal sites are often characterized by phytotoxic ...levels of trace elements (TE) (Cu, Fe, Mn, and Zn) and low nutrient status (N, P, and K). The aim of this study was to test the effect of digestate and bacterial inoculation on soil physicochemical properties (pH, CaCl2 extractable Mn, and microbial enzyme activities) and birch (Betula pendula) growth and physiology on a red gypsum substrate in a lab-to-field experimental approach. The biomass of birches amended with digestate (D0.05% N) was on average 2- and 6-fold greater than that of control birch in the laboratory and field experiments, respectively. A higher concentration of digestate (0.1% N) had an inhibitory effect on plant growth, and reduced the survival rates of amended plants by 40% as compared with controls. The digestate (D0.05% N) treatment significantly increased leaf P and K contents while decreasing leaf Ca, Fe and Mn contents. Digestate also increased some key soil enzyme activities of C, N, P and S metabolism by >10-fold compared with the control soil. In a phytomanagement scenario, digestate would be a preferred amendment resource for the production of clean birch leaf biomass on contaminated red gypsum landfill, as birch trees amended with digestate had lower leaf TE and higher leaf nutrient contents than control birches.
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•Digestate and bacterial inoculum were used to improve birch growth on red gypsum.•The digestate significantly increased birch biomass as well as leaf P and K content.•The two amendments decreased the leaf Fe, Mn and Zn contents.•Soil functionalities were enhanced upon digestate amendments.
Purpose
This study evaluates the effects of two soil amendments and the growth of two plant species on labile trace element (TE) fractions in two different contaminated soils.
Materials and methods
...We studied the effects of two organic amendments (biosolid compost and alperujo compost) and two plant species (
Medicago polymorpha
and
Poa annua
) on pH, total organic carbon (TOC), and TE availability, by three extraction methods (CaCl
2
aqueous solution, soil pore water (SPW), and diffusive gradient in thin film (DGT)), in two contaminated soils with contrasting pH values (Aznalcázar, 6.53, and Vicario, 3.48) in a 118-day pot experiment. The effects of the composts on labile TE fractions were compared with element concentrations in plants.
Results and discussion
No relevant effects of amendments and plants were found on the physical and chemical characteristics of the Aznalcázar soil. However, the addition of amendments was essential for plant species growing in the acid Vicario soil. In this soil, amendments and plant growth increased pH and TOC and reduced substantially TE bioavailability. Although absolute values of bioavailable TE contents obtained by the three methods were very different and followed the trend CaCl
2
extraction > SPW > DGT, these values follow a similar behavior in the two studied soils and for the two species.
Conclusions
The results demonstrate that the application of organic amendments are suitable for remediating acid TE-contaminated soils, for the establishment of a vegetation cover on previously bare soils for reducing wind and water erosion and for reducing labile TE fractions to prevent leaching of pollutants into subsoil or groundwater layers. Moreover, the results obtained in this study pointed out that under microcosm conditions, the three methods tested (CaCl
2
extraction, SPW, and DGT) to predict TE bioavailability were highly correlated.
The effects of the Populus alba tree on different biochemical soil properties, growing in a contaminated area, were studied for two years under field conditions. Two types of trace element ...contaminated soils were studied: a neutral contaminated soil (NC) and an acid contaminated soil (AC). One neutral non-contaminated area was studied as control. Soil samples were collected at depths of 0–20 cm and 20–40 cm. Leaves and litter samples were analysed. The addition of organic matter, through root exudates and litter, contributed to an increase in soil pH, especially in acid soil. Microbial Biomass Carbon (MBC) was significantly increased by the presence of the trees in all studied areas, especially in the upper soil layer. Similar results were also observed for protease activity. Both MBC and Protease activity were more sensitive to contamination than β-glucosidase activity. These changes resulted in a decrease of available trace element concentrations in soil and in an improvement of soil quality after a 2-year study. The total concentration of Cd and Zn in soil did not increase over time due to litter deposition. Analysis of P. alba leaves did not show a significant nutritional imbalance and trace element concentrations were normal for plants, except for Cd and Zn. These results indicate that P. alba is suitable for the improvement of soil quality in riparian contaminated areas. However, due to the high Cd and Zn concentrations in leaves, further monitoring of this area is required.
•P. alba presence improves biochemical soil properties and nutrient cycling.•The addition of organic matter content by litter decomposition influenced soil pH.•Cd and Zn total content in soil was not increased in time due to litter deposition.•P. alba is suitable for improving soil quality of riparian contaminated areas.
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•38 tree species were tested for the phytomanagement of different marginal lands.•O. carpinifolia performed well on the three sites compared to the nursery standard.•The PTE contents ...in the trees strongly differed depending on the species.•S. aquatica grandis exhibited the highest accumulation capacity at the three sites.
The use of fast-growing trees producing a high quantity of biomass can bring significant practical and economic benefits to the reclamation of marginal lands. The present study aims to identify new shrub/tree species to offer a wider range of shrubs/trees useful for phytomanagement practices. We implemented three experimental sites in France of 1 ha each (Thann, Carrières-sous-Poissy and Leforest) contaminated by different potentially toxic elements (PTE) with a total of 38 different tree species. After two years of growth, the element concentrations in stem and leaf biomasses, tree survival rate and growth of plants were assessed. Although the three sites had elevated concentrations of total PTE and nutrients in their soil, the element contents in the trees strongly differed depending on the species. Alnus subcordata, Platanus orientalis, Ulmus pumila, Ostrya carpinifolia and the Acer species appeared to be well adapted to the drastic conditions of the sites and presented the lowest PTE concentrations in their aboveground biomass. Conversely, the Salix, Populus, Betula and Quercus species, especially Salix aquatica grandis, exhibited the highest accumulations of Cd, Zn and/or Mn at the three sites. Inoculation with the endomycorrhizal fungus Rhizophagus irregularis did not have a significant impact on the growth of the tree species at the three sites after two growing seasons. Overall, the present study offers two options for the phytomanagement of marginal lands. The first option is based on the production of clean biomass, which is useful for plant-based industrial processes (e.g., biomaterials, bioenergy) that could valorize this biomass. The second option is based on the production of TE-enriched biomass that could be better exploited in the eco-catalysis process.
This study deals with approaches for a social-ecological friendly European bioeconomy based on biomass from industrial crops cultivated on marginal agricultural land. The selected crops to be ...investigated are: Biomass sorghum, camelina, cardoon, castor, crambe, Ethiopian mustard, giant reed, hemp, lupin, miscanthus, pennycress, poplar, reed canary grass, safflower, Siberian elm, switchgrass, tall wheatgrass, wild sugarcane, and willow. The research question focused on the overall crop growth suitability under low-input management. The study assessed: (i) How the growth suitability of industrial crops can be defined under the given natural constraints of European marginal agricultural lands; and (ii) which agricultural practices are required for marginal agricultural land low-input systems (MALLIS). For the growth-suitability analysis, available thresholds and growth requirements of the selected industrial crops were defined. The marginal agricultural land was categorized according to the agro-ecological zone (AEZ) concept in combination with the marginality constraints, so-called ‘marginal agro-ecological zones’ (M-AEZ). It was found that both large marginal agricultural areas and numerous agricultural practices are available for industrial crop cultivation on European marginal agricultural lands. These results help to further describe the suitability of industrial crops for the development of social-ecologically friendly MALLIS in Europe.
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