• Energy Research
• 13. Climate action close

The disposal of coal combustion residues (CCR) has led to a significant consumption of land in the West Balkan region. In Tuzla (Bosnia and Herzegovina) we studied previously soil-covered (farmed) and barren CCR landfills including management practises, field ageing of CCR and the transfer of trace elements into crops, wild plants and wastewaters. Soil tillage resulted in mixing of cover soil with CCR. Medicago sativa showed very low Cu:Mo ratios (1.25) which may cause hypocuprosis in ruminants. Total loads of inorganic pollutants in the CCR transport water, but not pH ( approximately 12), were below regulatory limits of most EU countries. Arsenic concentrations in CCR transport water were <2microgl(-1) whereas reductive conditions in an abandoned landfill significantly enhanced concentrations in leachates (44microgl(-1)). The opposite pattern was found for Cr likely due to large initial leaching of CrVI. Public use of landfills, including farming, should be based on a prior risk assessment due to the heterogeneity of CCR.

A questionnaire survey was carried out in four European countries to gather end-user's perceptions of using plants from phytotechnologies in combustion and anaerobic digestion (AD). Nine actors of the wood energy sector from France, Germany, and Sweden, and eleven AD platform operators from France, Germany, and Austria were interviewed. Questions related to installation, input materials, performed analyses, phytostabilization, and phytoextraction were asked. Although the majority of respondents did not know phytotechnologies, results suggested that plant biomass from phytomanaged areas could be used in AD and combustion, under certain conditions. As a potential benefit, phytomanaged plants would not compete with plants grown on agricultural lands, contaminated lands being not suitable for agriculture production. Main limitations would be related to additional controls in process' inputs and end-products and installations that might generate additional costs. In most cases, the price of phytotechnologies biomass was mentioned as a driver to potentially use plants from metal-contaminated soils. Plants used in phytostabilization or phytoexclusion were thought to be less risky and, consequently, benefited from a better theoretical acceptance than those issued from phytoextraction. Results were discussed according to national regulations. One issue was related to the regulatory gap concerning the status of the plant biomass produced on contaminated land.

Gentle remediation options (GRO) are based on the combined use of plants, associated microorganisms and soil amendments, which can potentially restore soil functions and quality. We studied the effects of three GRO (aided-phytostabilisation, in situ stabilisation and phytoexclusion, and aided-phytoextraction) on the soil microbial biomass and respiration, the activities of hydrolase enzymes involved in the biogeochemical cycles of C, N, P, and S, and bacterial community structure of trace element contaminated soils (TECS) from six field trials across Europe. Community structure was studied using denaturing gradient gel electrophoresis (DGGE) fingerprinting of Bacteria, α- and β-Proteobacteria, Actinobacteria and Streptomycetaceae, and sequencing of DGGE bands characteristic of specific treatments. The number of copies of genes involved in ammonia oxidation and denitrification were determined by qPCR. Phytomanagement increased soil microbial biomass at three sites and respiration at the Biogeco site (France). Enzyme activities were consistently higher in treated soils compared to untreated soils at the Biogeco site. At this site, microbial biomass increased from 696 to 2352 mg ATP kg-1 soil, respiration increased from 7.4 to 40.1 mg C-CO2 kg-1 soil d-1, and enzyme activities were 2-11-fold higher in treated soils compared to untreated soil. Phytomanagement induced shifts in the bacterial community structure at both, the total community and functional group levels, and generally increased the number of copies of genes involved in the N cycle (nirK, nirS, nosZ, and amoA). The influence of the main soil physico-chemical properties and trace element availability were assessed and eventual site-specific effects elucidated. Overall, our results demonstrate that phytomanagement of TECS influences soil biological activity in the long term.

La contamination par le pétrole et son assainissement via des solutions à base de plantes ont suscité une attention croissante de la part des scientifiques et des ingénieurs de l'environnement. Dans la présente étude, les réponses physiologiques et de croissance de deux espèces végétales tolérantes au diesel (limite de tolérance : 1500-2000 mg/kg), le ray-grass italien (Lolium multiflorum) et le trèfle à pattes d'oiseau (Lotus corniculatus), ont été étudiées dans des sols modifiés à l'huile végétale et au diesel. Une expérience de pot à effet de serre à long terme (147 jours) a été menée pour différencier l'objectif principal de l'étude : les effets physiques et chimiques de l'huile (végétale et diesel) dans les sols fraîchement dopés en évaluant les performances de la plante et la dégradation des hydrocarbures. De plus, les performances des plantes ont été évaluées en termes de germination des graines, de biomasse des pousses des plantes, de paramètres physiologiques et de biomasse racinaire. L'ajout d'huile diesel et d'huile végétale dans des sols fraîchement dopés a montré des effets délétères sur l'émergence des semis, la biomasse racinaire et la teneur en chlorophylle des plantes herbacées et légumineuses. Le ray-grass italien a montré une plus grande sensibilité en termes de taux de germination à la fois à l'huile végétale et à l'huile diesel par rapport aux sols non contaminés, tandis que le trèfle à pattes d'oiseau a réduit le taux de germination uniquement dans les sols impactés par l'huile diesel. Les résultats de la présente étude suggèrent que les effets physiques et chimiques de l'huile posent des effets négatifs sur la croissance des plantes et le développement des racines. Cette observation peut expliquer le phénomène de croissance réduite des plantes dans les sols contaminés vieillis/altérés au cours des expériences de rhizoremédiation. La contaminación por petróleo y su remediación a través de soluciones basadas en plantas han recibido cada vez más atención por parte de científicos e ingenieros ambientales. En el estudio actual, se han investigado las respuestas fisiológicas y de crecimiento de dos especies de plantas tolerantes al diésel (límite de tolerancia: 1500-2000 mg/kg), el raigrás italiano (Lolium multiflorum) y el trébol de pie de ave (Lotus corniculatus), en suelos modificados con aceite vegetal y aceite diésel. Se realizó un experimento de maceta de invernadero a largo plazo (147 días) para diferenciar el enfoque principal del estudio: los efectos físicos y químicos del aceite (vegetal y diesel) en suelos recién enriquecidos mediante la evaluación del rendimiento de la planta y la degradación de los hidrocarburos. Además, se evaluó el rendimiento de las plantas en términos de germinación de semillas, biomasa de brotes de plantas, parámetros fisiológicos y biomasa de raíces. La adición de aceite diesel y aceite vegetal en suelos recién enriquecidos mostró efectos nocivos sobre la emergencia de plántulas, la biomasa de raíces/brotes y el contenido de clorofila de las plantas de pasto y leguminosas. El raigrás italiano mostró más sensibilidad en términos de tasa de germinación tanto al aceite vegetal como al diesel en comparación con los suelos no contaminados, mientras que el trébol Birdsfoot redujo la tasa de germinación solo en suelos impactados por el diesel. Los resultados del estudio actual sugieren que tanto los efectos físicos como químicos del aceite plantean efectos negativos del crecimiento de las plantas y el desarrollo de las raíces. Esta constatación puede explicar el fenómeno de la reducción del crecimiento de las plantas en suelos contaminados envejecidos/erosionados durante los experimentos de rizorremediación. Petroleum contamination and its remediation via plant-based solutions have got increasing attention by environmental scientists and engineers. In the current study, the physiological and growth responses of two diesel-tolerant plant species (tolerance limit: 1500-2000 mg/kg), Italian ryegrass (Lolium multiflorum) and Birdsfoot trefoil (Lotus corniculatus), have been investigated in vegetable oil- and diesel oil-amended soils. A long-term (147-day) greenhouse pot experiment was conducted to differentiate the main focus of the study: physical and chemical effects of oil (vegetable and diesel) in freshly spiked soils via evaluating the plant performance and hydrocarbon degradation. Moreover, plant performance was evaluated in terms of seed germination, plant shoot biomass, physiological parameters, and root biomass. Addition of both diesel oil and vegetable oil in freshly spiked soils showed deleterious effects on seedling emergence, root/shoot biomass, and chlorophyll content of grass and legume plants. Italian ryegrass showed more sensitivity in terms of germination rate to both vegetable and diesel oil as compared to non-contaminated soils while Birdsfoot trefoil reduced the germination rate only in diesel oil-impacted soils. The results of the current study suggest that both physical and chemical effects of oil pose negative effects of plant growth and root development. This observation may explain the phenomenon of reduced plant growth in aged/weathered contaminated soils during rhizoremediation experiments. وقد حظي التلوث النفطي ومعالجته عن طريق الحلول النباتية باهتمام متزايد من قبل العلماء والمهندسين البيئيين. في الدراسة الحالية، تم التحقيق في الاستجابات الفسيولوجية والنمو لنوعين من النباتات التي تتحمل الديزل (حد التحمل: 1500-2000 مجم/كجم)، الريجراس الإيطالي (Lolium multiflorum) و Birdsfoot trefoil (Lotus corniculatus)، في التربة المعدلة بالزيت النباتي وزيت الديزل. تم إجراء تجربة وعاء دفيئة طويلة الأجل (147 يومًا) للتمييز بين التركيز الرئيسي للدراسة: الآثار الفيزيائية والكيميائية للزيت (الخضروات والديزل) في التربة الطازجة من خلال تقييم أداء النبات وتدهور الهيدروكربونات. علاوة على ذلك، تم تقييم أداء النبات من حيث إنبات البذور، والكتلة الحيوية للنباتات، والمعلمات الفسيولوجية، والكتلة الحيوية الجذرية. أظهرت إضافة كل من زيت الديزل والزيت النباتي في التربة المسننة الطازجة آثارًا ضارة على ظهور الشتلات، والكتلة الحيوية الجذرية/البراعم، ومحتوى الكلوروفيل في نباتات العشب والبقوليات. أظهر نبات الريجراس الإيطالي حساسية أكبر من حيث معدل الإنبات لكل من الزيوت النباتية وزيت الديزل مقارنة بالتربة غير الملوثة بينما قلل نبات البيردسفوت تريفويل من معدل الإنبات فقط في التربة المتأثرة بزيت الديزل. تشير نتائج الدراسة الحالية إلى أن الآثار الفيزيائية والكيميائية للزيت تشكل آثارًا سلبية لنمو النبات وتطور الجذر. قد تفسر هذه الملاحظة ظاهرة انخفاض نمو النبات في التربة الملوثة القديمة/المعرضة للتلوث أثناء تجارب معالجة الجذور.