Impact of heavy metals in sewage sludge on soil and plants (colza and wheat)

National audienceWe are testing the impact of heavy metals in sludge from urban and industrial wastewater treatment plants. We try to understand their influence on plant growth and their bioaccumulation. We chose two plants: the wheat and rapeseed to their specific characteristics; wheat is a herbaceous low accumulator of heavy metals, however rape (colza) is a plant of the family Brassica napus, is an excellent bio-accumulator of heavy metals. The mean levels found in the soil are organized in the following order: Fe >> Mn> Zn> Pb> Cu> Ni> Co> Cd. The contents of heavy metals in the sludge is made very high and exceed European values allowed for that type of use but remain in the standard NT106 Tunisia. The effects of the contribution of sludge are manifested by a significant increase in the weight gains of the whole plant, these results in a variation of the ratio between the aerial part and roots of the plant; this ratio tends to increase with dose of mud brought in soil increase. The roots of both plants show high levels of Zn even on the ground untreated control. The contents of Ni, Pb and Zn compared to Cu and Co are higher in the roots of rape than wheat

Transfert heavy metal sewage sludge as fertilizer from soil to ray grass

International audienceThe land application of sewage sludge reveals a significant increase in dray matter production of Ray Grass (Lolium perenne L.). In equivalent dose of liquid sludge, we registered a lower production of dry material. Besides, neither the dose nor type of sludge seems to have an effect on heavy metals contents in the air part plant. On the other hand, contribution of sludge under dry or liquid forms increases significantly heavy metals contents in roots with regard to witness without sludge. The comparison between the beginning and end of culture, revealed a decrease heavy metals contents in soil in particular at horizon 0-40 cm deep. Besides, this decrease Cd, Zn, Pb and Cu contents in soil is not linking to transfer from soil to air part of plant, but rather is the accumulation in roots, which play the role of a barrier

Growth and photosynthesis responses of Rosmarinus officinalis L. to heavy metals at Bougrine mine

Heavy metals pollution is considered as one of the most dangerous environmental problems in agricultural soil, particularly neighboring mining sites. Phytoremediation based on green plants use seems to be an interesting biological solution to detoxify these soils. This study focuses especially on heavy metals effects on Rosmarinus officinalis L. morphological and growth parameters. The site of our research is “Bougrine” mine which represents different zinc, lead and cadmium amounts by geological layers. In opposite to amounts obtained by previous studies made for mining exploration, we thought that zinc content was more important at transition zone than Cenomanian Turonian level. Nevertheless, this element is not the most determinant in plant growth and its morphological parameters. Moreover, R. officinalis L. volume and vigor decreased when soil’s heavy metals content increases. However, this reduction is more related to soil lead content. Despite this decrease, we do not observe any visual phytotoxicity symptom. This aromatic and medicinal species, belonging to Lamiaceae family, could be used as alternative crops in polluted soils.Keywords: Rosmarinus officinalis L., zinc, lead, growth, photosynthesis, “Bougrine” mineAfrican Journal of Biotechnology Vol. 12(2), pp. 150-16

L'effet des boues d'épuration (liquides et sèches) sur l'absorption des métaux lourds par le ray grass (<i>Lolium Perenne</i>)

National audienceL'épandage des boues résiduaires liquides et sèches a entraîné une augmentation de la production de la biomasse du Ray Grass. Cette augmentation est fonction des doses croissantes appliquées. Cet effet positif des boues sur les rendements a été constaté sur d'autres cultures. En effet, de nombreux auteurs ont signalé une augmentation significative des rendements de différentes cultures tels que le sorgho, le maïs, le piment, la pomme de terre. Nos essais ont également montré un meilleur rendement avec la boue sèche qu'avec la boue liquide l'année de l'épandage. Ceci pourrait également être le résultat d'une part d'une perte probable des nitrates apportés dans les boues liquides et d'autre part de la richesse de la boue apportée en matière sèche. En effet, la teneur de la boue en matière sèche est très variable soit environ 5% et 67% de matière sèche respectivement dans la boue liquide et la boue sèche. Pour ce qui est de l'accumulation des métaux lourds dans la plante, nos résultats ont montré que les teneurs en Cd, Pb, Zn, et Cu de la partie aérienne de la plante ne varient pas avec l'apport de 5 et 10 t/ha de boue sèche ou liquide. Ces résultats sont en accord avec ceux qui ont étudié l'évolution des teneurs en plomb des tissus du ray-grass, soumis à trois types de traitement (témoin sans apport, fertilisation minérale et amendement en boues). Ils ont montré qu'il n'existe aucune différence significative entre les quantités moyennes de plomb des différentes récoltes de ray-grass, issus des différents traitements d'une même série de culture, effectuées à une même date. Ils ont constaté le même effet pour le Zn

Behavior canola (<i>Brassica Napus</i>) following a sewage sludge treatment

International audienceIn this study, two types of sludge were being used, while the first was with urban dominance, the second was with industrial dominance. The effects of sewage sludge had been studied in a Brassica Napus field. The mineralogical, chemical and microscopic study of the sludge showed that industrial sludge had very high levels of Cr, Pb and Cd. These metals existed mainly under the form of daubreelita Cr2FeS4, brezininaite Cr3S4, wattersite Hg5CrO6, crocoite PbC2O4, pheonicochroite Pb2O(CrO4) and Pb-oxalate PbC2O4. The results showed that sludge significantly improves the growth of the underground part of the plant (root) and the upper part (stem, leaves etc...). This improvement is more important for urban sludge. However, this beneficial effect was accompanied by a change in the composition of the plant some trace element metals. An abnormal accumulation of Cr was found in the roots, stem, leaves, and siliques when the industrial sludge was brought which reflected the richness of the latest. The dose-effect sewage sludge was very clear at the levels of Pb in the roots especially for industrial sludge which exceeded the threshold values of toxicity starting from the dose of 25t/ha of industrial sludge. Cd levels only increased with the addition of 100t/ha of industrial sludge. For Ni, Cu, Co and Zn, especially at roots level, the increase depends on mud's dose and especially on its type. On the contrary, levels of iron, and to a less extent manganese levels, had been reduced due to sludge despite their richness with these elements. That was probably due to antagonism with one or more particular elements especially Zn

Transfer heavy metal from soil treated to colza

International audienceThe impact of heavy metals were tested in sludge from urban and industrial wastewater treatment plants, trying to understand their influence on colza growth and their bioaccumulation. We chose the colza to their specific characteristics. The colza is a plant of the family Brassica Napus, is an excellent bio-accumulator of heavy metals. The mean levels found in the soil are organized in the following order: Fe >> Mn> Zn> Pb> Cu> Ni> Co> Cd. The contents of heavy metals in the sludge are very high and exceed European values allowed for that type of use. The effects of the contribution of sludge are manifested by a significant increase in the heavy metals of the colza, these results in a variation of the ratio between the aerial part and roots of the plant; this ratio tends to increase with the dose of mud brought in soil. The roots of plants show high levels of Zn even on the ground of untreated soil. The contents of Ni, Pb and Zn, compared to Cu and Co, are higher in the roots of colza

Contribution à l'étude de la matière organique dans les sols des nappes alfatières en Tunisie centrale : minéralisation de l'azote et du carbone

Thèse, Université de Tunis, 198

Incidence of sewage sludge fertilizer application on Ray Grass (Morocco)

International audienceThe land application of sewage sludge reveals a significant increase in the dry matter production of RayGrass. In equivalent dose of liquid mud, we registered a lower production of dry material, which could be the resultof a loss though lixiviation of a quantity of nitrogen brought by mud. Besides, neither the dose nor the type of mudseems to have an effect on the Pb, Cd, Cu and Zn contents in the air part of the plant. On the other hand, it noticedthat the contribution of mud under dry or liquid forms increases significantly the contents of Cd, Pb and of Zn inroots with regard to the witness without mud.The comparison between the beginning and the end of culture, revealed a decrease of the content in Cd, Zn, Pb andCu in the ground in particular at the level of the superficial coats (0-40 cm). Besides, this decrease of the contents inCd, Zn, Pb and Cu in the ground is in no case connected to increase in the air part of the plant but rather, is for anaccumulation in the roots, which play the role of a barrier, or a migration of these elements beyond roots

Comparaison des effets de la contrainte hydrique sur la croissance, la conductance stomatique et la photosynthèse de jeunes plants de chênes méditerranéens (Quercus suber, Q. faginea, Q. coccifera) en Tunisie

Une étude comparative des réponses physiologiques de jeunes plants de chênes sempervirents (chêne liège : Quercus suber L. et chêne kermès : Q. coccifera L.) et d'un chêne caducifolié (chêne zéen : Q. faginea Willd) a été menée en pépinière à Tunis. Des plants de 6 et 18 mois, élevés en pots, ont été soumis à une contrainte hydrique par arrêt d'arrosage pendant deux cycles de dessèchement consécutifs d'une durée de deux mois. Nous avons mesuré les potentiels hydriques de base et minimum, la perte en eau par rapport à la capacité au champ (transpiration cumulée des plantes), la conductance stomatique et l'assimilation photosynthétique. La biomasse des tiges, des racines, les rapports biomasse tige/racine et la surface foliaire ont été également déterminés. Le rapport biomasse tige/racine a diminué davantage au cours de la contrainte hydrique chez Q. faginea que chez Q. coccifera. La diminution de la conductance stomatique, liée à la chute du potentiel hydrique foliaire de base, était plus précoce chez Q. faginea. Les stomates de Q. coccifera sont restés encore partiellement ouverts pour des potentiels de l'ordre de - 3MPa. Les réponses de Q. suber étaient intermédiaires. La photosynthèse nette et la conductance stomatique étaient étroitement corrélées et présentaient toutes deux une dépression de milieu de journée. Nos résultats indiquent qu'il serait nécessaire d'approfondir les études écophysiologiques en fonction de l'âge des plants et des feuilles au stade juvénile, pour mieux comprendre le comportement des chênes, notamment ses difficultés de régénération spontanée. (© Inra/Elsevier, Paris.)Comparison of the water stress effects on stomatal conductance, photosynthesis and growth of Mediterannean oak seedlings (Quercus suber L., Q. faginea, Q. coccifera) in Tunisia. Two evergreen oaks (Quercus suber L., Q. coccifera) and one deciduous oak (Q. faginea Willd.) were subjected to drought in a nursery in Tunis. Six- and 18-month-old seedlings were grown in pots and underwent two cycles of drought by withholding water supply. Predawn and midday leaf water potentials, stomatal conductance, photosynthesis and plant transpiration were recorded. An analysis of root and shoot biomass, shoot-to-root ratio and leaf area was also performed. Our results showed a higher reduction of shoot-to-root biomass ratio of Q. faginea compared to Q. coccifera under water limitation. The stomatal conductance decrease, related to the decrease of predawn leaf water potential, occurred earlier with Q. faginea. Q. coccifera kept its stomata partly open at a water potential of -3.0 MPa. Q. suber behaved somewhat intermediate. Photosynthesis and stomatal conductance were correlated and showed a midday depression. Our results indicate that more ecophysiological studies are required to take into account seedling and leaf ages during the juvenile stage for a better understanding of the water stress responses of these species and regeneration problems of oaks. (© Inra/Elsevier, Paris.