Transfer and accumulation of lead, zinc, cadmium and copper in plants growing in abandoned mining-district area

The analysis of the Jebel Hallouf-Sidi Bouaouane mining-district soil has shown that the surface horizons are strongly contaminated by heavy metals, especially during floods or in lee-side areas. The contents of metallic-trace elements (MTE), in the soil and two cultivated plant species, have been determined by Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES). The results show that the concentration of metals in the soil are up to 39 g. kg-1, 6.3 g. kg-1, 56 mg. kg-1 and 131 mg. kg-1, for lead (Pb), zinc (Zn), cadmium (Cd) and copper (Cu), respectively. The chemical analysis of plants: broad beans [Vicia faba (L.)] and barley [Hordeum vulgare (L.)], sampled inside the mining district, show that the roots and the upper part (leaves and stem) are enriched for Pb (up to 508 and 220 mg.kg-1, respectively), Cd (up to 8 and 5 mg.kg-1, respectively), and Zn (up to 491 and 468 mg.kg-1, respectively) when compared with similar species collected far from the contaminated site (up to 9.6 and 0.8 mg.kg-1 for Pb, up to 0.04 and 0.04 mg.kg-1 for Cd, up to 44 and 15 mg.kg-1 for Zn, respectively). Statistically, the concentration of MTE in the soils and plants of the mining area is significantly different from the concentrations of the same elements in the soils and plants of the control ones (p < 0.01). This is expressed by a strong Enrichment Coefficient (EC), which is given by the ratio between the concentration of the metal in the contaminated plant and the concentration of the same element in the similar control one. The results (up to 405, 342 and 32, respectively), indicate that the contamination has reached the first link of the food chain. However, the calculation of the translocation factor (TF), deduced from the ratio between the concentration of the metal in the outer part of the plant and the concentration of the same element in the roots, shows that, the broad beans accumulates metals in the roots (TF < 1); whereas for barley, metals are fairly distributed between the roots and the outer part (TF ≈ 1). These results suggest that the cultivated areas inside the mining district constitute a serious source of contamination of the food chain. Therefore, actions have to be taken in order to remedy this problem.Key words: MTE, contamination, transfer, soil, plant

Linking disease epidemiology and livestock productivity: the case of bovine respiratory disease in France

Concerns are growing over the impact of livestock farming on environment and public health. The livestock industry is faced with the double constraint of limiting its use of natural resources and antimicrobials while ensuring its economic sustainability. In this context, reliable methods are needed to evaluate the effect of the prevention of endemic animal diseases on the productivity of livestock production systems. In this study, an epidemiological and productivity model was used to link changes in Bovine Respiratory Disease (BRD) incidence with the productivity of the beef and dairy cattle sectors in France. Cattle production parameters significantly affected by BRD were selected through literature review. Previous field study results and national cattle performance estimates were used to infer growth performances, mortality rates and carcass quality in the cattle affected and not affected by BRD. A steady-state deterministic herd production model was used to predict the productivity of the dairy and beef sector and their defined compartments (breeding-fattening, feedlot young bulls, and feedlot veal) in case of BRD incidence reduction by 20%, 50% or 100%. Results suggested that BRD should be controlled at a priority in beef breeding farms as eradication of BRD in beef calves would increase the whole beef sector’s productivity by 4.7–5.5% while eradication in other production stages would result in lower productivity gain in their respective sectors. However, the analysis performed at compartment level showed that, in both the beef and dairy sector, young bull and veal feedlot enterprises derive more economic benefits from BRD eradication for their own compartment (increase in productivity of 8.7–12.8% for beef young bulls) than the breeding farms (increase in productivity of 5.1–6% for beef calves), which may limit the investments in BRD control

Deep crustal source of gneiss dome revealed by eclogite in migmatite (Montagne Noire, French Massif Central)

International audienceIn orogens worldwide and throughout geologic time, large volumes of deep continental crust have been exhumed in domal structures. Extension‐driven ascent of bodies of deep, hot crust is a very efficient mechanism for rapid heat and mass transfer from deep to shallow crustal levels and is therefore an important mechanism in the evolution of continents. The dominant rock type in exhumed domes is quartzofeldspathic gneiss (typically migmatitic) that does not record its former high‐pressure (HP) conditions in its equilibrium mineral assemblage; rather, it records the conditions of emplacement and cooling in the mid/shallow crust. Mafic rocks included in gneiss may, however, contain a fragmentary record of a HP history, and are evidence that their host rocks were also deeply sourced. An excellent example of exhumed deep crust that retains a partial HP record is in the Montagne Noire dome, French Massif Central, which contains well‐preserved eclogite (garnet+omphacite+rutile+quartz) in migmatite in two locations: one in the dome core and the other at the dome margin. Both eclogites record P ~ 1.5 ± 0.2 GPa at T ~ 700 ± 20°C, but differ from each other in whole‐rock and mineral composition, deformation features (shape and crystallographic preferred orientation, CPO), extent of record of prograde metamorphism in garnet and zircon, and degree of preservation of inherited zircon. Rim ages of zircon in both eclogites overlap with the oldest crystallization ages of host gneiss at c. 310 Ma, interpreted based on zircon rare earth element abundance in eclogite zircon as the age of HP metamorphism. Dome‐margin eclogite zircon retains a widespread record of protolith age (c. 470–450 Ma, the same as host gneiss protolith age), whereas dome‐core eclogite zircon has more scarce preservation of inherited zircon. Possible explanations for differences in the two eclogites relate to differences in the protolith mafic magma composition and history and/or the duration of metamorphic heating and extent of interaction with aqueous fluid, affecting zircon crystallization. Differences in HP deformation fabrics may relate to the position of the eclogite facies rocks relative to zones of transpression and transtension at an early stage of dome development. Regardless of differences, both eclogites experienced HP metamorphism and deformation in the deep crust at c. 310 Ma and were exhumed by lithospheric extension—with their host migmatite—near the end of the Variscan orogeny. The deep crust in this region was rapidly exhumed from ~50 to <10 km, where it equilibrated under low‐P/high‐T conditions, leaving a sparse but compelling record of the deep origin of most of the crust now exposed in the dome