Influence of fine process particles enriched with metals and metalloids on Lactuca sativa L. leaf fatty acid composition following air and/or soil-plant field exposure

We investigate the effect of both foliar and root uptake of a mixture of metal(loid)s on the fatty acid composition of plant leaves. Our objectives are to determine whether both contamination pathways have a similar effect and whether they interact. Lactuca sativa L. were exposed to fine process particles enriched with metal(loid)s in an industrial area. Data from a first experiment were used to conduct an exploratory statistical analysis which findings were successfully cross-validated by using the data from a second one. Both foliar and root pathways impact plant leaf fatty acid composition and do not interact. Z index (dimensionless quantity), weighted product of fatty acid concentration ratios was built up from the statistical analyses. It provides new insights on the mechanisms involved in metal uptake and phytotoxicity. Plant leaf fatty acid composition is a robust and fruitful approach to detect and understand the effects of metal(loid) contamination on plants

Are plants useful as accumulation indicators of metal bioavailability?

International audienceThe use of accumulation bioindicator to assess metal bioavailability has mainly concerned individual species. This work addresses this issue at the plant community level. Metal content within different species from plant communities found at three contaminated and one uncontaminated site was compared. Results showed that for two contaminated sites, leaf metals concentrations were comparable to those in plants from control site, i.e. approx (mg/kg) 0.1 Cd, 0.2 Cr, 9.2 Cu, 1.8 Ni, 0.5 Pb and 42 Zn. Only plants from the third site showed higher metal contents, ranging from 1.5- to 8-fold those of the control community. This contrasted with ammonium acetate-EDTA extractions, which indicated a very high "availability" of metals at the three sites, as compared to the control site. Thus, metal content in plant communities provided accurate information on actual transfer toward the ensemble of vegetation, which could be used to establish site-specific "fingerprints" of metal bioavailability

Early changes in the fatty acid composition of photosynthetic membrane lipids from "Populus nigra" grown on a metallurgical landfill

International audienceWe compared the fatty acid composition of leaves taken from poplars ona metal-contaminated landfill, and on the uncontaminated roadside bordering this site. For the first time, it is shown that the percentage of linolenic acid, which is mainly associated with thylakoid lipids, was significantly lower in tree species within the landfill than within the control area. A correlation study was carried out to investigate relationships between the C18:3/(C18:0 + C18:1 + C18:2) fatty acid ratios and the metal contents in soils and leaves. Lead and chromium leaf contents were significantly negatively correlated to this fatty acid ratio. The impact of each of these metals remains difficult to evaluate, but chromium in leaf likely plays a major role in toxicity. In addition, the decrease in the C18:3/(C18:0 + C18:1 + C18:2) fatty acid ratio occurred at low leaf metal content, and therefore it is shown that this ratio can be used as an early indicator of the effect of metals

Phos4You project : phosphorus availability of phosphorus fertilizers recovered from municipal wastewater

The current European Fertilizer Regulation1, next to the national legislation2, implies the use of several different chemical methods to assess phosphorus (P) availability in fertilizers. The variety of those methods is large and comparison between them is difficult. With the emerging production of recovered P fertilizers, adequate measurements of P availability are needed. The Interreg project Phos4You recognizes this demand for standardized quality assessment methodology, in particular P availability. Ten different chemical P extraction and two P determination methods are being evaluated on struvites, P-slag, Fe-P pellets and ash recovered from municipal waste water and compared to triple superphosphate. Also, plant experiments are being carried out in pot and field trials. Multi-nutrient fertilizer (NIST SRM) is used as a reference. Pot trials are conducted with 3.5 g/m3 seeds of ryegrass and P-poor substrate soil, with incremental addition of fertilizer (30, 60 and 90 kg P2O5/ha). Essential nutrients other than P are being supplied with continuous addition of Hoagland solution to avoid deficiencies for other nutrients. Pot trials are run in parallel in 3 countries (BE, IR, FR). The first pot trial mimics plant uptake measurements with passive sampling techniques (i.e. Diffusive Gradient in Thin films (DGT) (iron-oxide binding layer), Rhizon and Plant Root Simulator (PRS) probes) on a weekly basis. Plant height and dry matter is being determined along with chemical P plant extraction measurements. In the second trial, P lipid index is examined as an early P availability indicator whereas the third trial focuses on field testing of struvite on different soil types (i.e. commonly found in Ireland and P-poor substrate soil). Moreover, field trials with struvite are run for scale validation where the product is being tested on two different soil types in Ireland. Chemical extraction methods, passive sampling techniques and biomarker experiments are being compared to find the most efficient way of measuring the P availability. It is hypothesized that biomarker and passive sampling methods can give fast results (compared to the pot experiment) with better correlation to real plant uptake than chemical extraction. The resulting standardized methodology will define the most effective P availability method for the various products from different processes and locations, while ensuring the applicability of the recycled material on the market

Impacts of heat stress and thermo-priming on seed yield and quality and on root exudation

International audienc

J Soils Sediments

Purpose: Arsenic (As) is one of the most widespread toxic elements, affecting human health through consumption of contaminated water or food. This work studied the effects of ammonium sulphate (NH4)2SO4 on mobility, speciation, and toxicity of As in a soil polluted by the destruction of chemical ammunition. Methods: Effects of fertilization on mobility and speciation of As, abundance of active AsIII-oxidizing and AsV-reducing microorganisms, abundance of bacterial 16S rRNA genes, and aioA and arsB genes involved in As biotransformation were monitored during barley growth in polluted (P) and non-polluted (NP) soils in pots maintained in outdoor conditions, with either the usual dose of (NH4)2SO4, 10 × or 100 × this dose. As transfer to plants and phytotoxicity were evaluated through quantification and speciation of As in grains and lipid peroxidation in plant leaves. Results: As mobility was significantly reduced by the highest dose of (NH4)2SO4. Fertilization tended to increase the Omega-3 Index in barley with the P soil. Abundance of AsIII-oxidizing microorganisms was higher and plant biomass was lower in P than in NP soil. Neither pollution level nor fertilization dose affected As speciation in soils or gene abundance. The sum of the concentrations of extracted AsIII and AsV species in grains was in the range 0–150 µg kg−1 with NP soil and 2000–3500 µg kg−1 with P soil. Conclusions: Results underline the importance of developing surveys of As dynamics in agricultural contexts with diverse types of crops, with a focus on As speciation mechanisms, linked to soil microbial activities and plant physiology

Quels bioindicateurs, pour quels besoins en sites contaminés ?

22 pInternational audienceActuellement, il existe un besoin de développer des outils pour répondre à plusieurs questions dans le souci d'améliorer les connaissances sur l'état biologique du sol et son fonctionnement ainsi que les phénomènes mis en cause : Comment mieux orienter le diagnostic physico-chimique des sols contaminés et détecter les substances polluantes (organiques et inorganiques) non suspectées ? Comment évaluer le comportement des polluants dans le sol, leur biodisponibilité et leur transfert vers les chaînes trophiques ? Comment évaluer un impact global d'un sol contaminé sur les écosystèmes terrestres (outils intégrateurs)? Comment évaluer l'état biologique d'un sol délaissé afin de le requalifier pour un usage futur

L'indice Oméga 3 des végétaux comme indicateurs de performances de procédés de traitement

International audienceThe Omega-3 Index of macrophytes to improve the assessment of the treatment performance of constructed wetlands receiving treated wastewater

Soil bioindicators : how soil properties influence their responses and how to select them in function of the site issues ?

EAGENOSOLECOLDURInternational audienceContext - Despite no directive exists for soil protection, this key component of ecosystem needs to be protected. To fill the lack of tools to monitor the soil threats and to assess the impact of soil management, biological indicators have been developed in the French program Bioindicators 2 (ADEME). On the 47 plots of 13 sites (agricultural, industrial and forest), the influence of soil characteristics and soil use on the response of 80 biological parameters (fauna, flora and microorganisms) have been assessed by using linear multivariate regressions. Results - The soil texture and the organic carbon rate has been identified as the main soil characteristic influencing the biological responses, even if each bioindicator is influenced by its own pool of soil parameters. It underlines the necessity to use battery of bioindicators for an integrative assessment of soil quality. An influence of soil contaminants (organic or metallic) have been highlighted for 86% of the bioindicators showing the necessity to consider their bioavailability for suitable soil management. To disseminate the use of bioindicators, a web interface has been implemented (http://ecobiosoil.univ-rennes1.fr/ADEME-Bioindicateur/). It presents all the biological methods developed in the program and allows consultation of the variation range of each bioindicator considering site contexts and soil physico-chemical characteristics of soils thus leading to provide a first benchmark. It also provides tools to the end-users to select the bioindicator(s) which best fit(s) with their own site problematic (agricultural practices, bioavailability of contaminants, soil monitoring...) and to communicate (technical sheets...). Conclusion – For the first time, the soil properties influence on the response of 80 bioindicators was characterized under similar environmental conditions. As each bioindicator is influenced by a specific pool of soil parameter, chemical measures cannot be used as a surrogate of biological measures. This program has provided usable tools for a biologically-based site management