The dynamic spillover effects of macroeconomic and financial uncertainty on commodity markets uncertainties

The present paper has two main objectives: first, to accurately estimate commodity price uncertainty; and second to analyze the uncertainty connectedness among commodity markets and the macroeconomic uncertainty, using the time-varying vector-autoregressive (TVP-VAR) model. We use eight main commodity markets, namely energy, fats and oils, beverages, grains, other foods, raw materials, industrial meals, and precious metals. The sample covers the period from January 1960 to June 2020. The estimated commodity price uncertainties are proven to be leading indicators of uncertainty rather than volatility in commodity markets. In addition, the time-varying connectedness analysis indicates that the macroeconomic uncertainty has persistent spillover effects on the commodity uncertainty, especially during the recent COVID-19 pandemic period. It has also found that the energy uncertainty shocks are the main drivers of connectedness among commodity markets, and that fats and oils uncertainty is the influence driver of uncertainty spillovers among agriculture commodities. The achieved results are of important significance to policymakers, firms, and investors to build accurate forecasts of commodity price uncertainties

Industrial fluoride pollution of Jerbi grape leaves and the distribution of F,Ca, Mg, and P in them

Fluoride damaged leaves of the Jerbi grape vine tree (Vitis vinifera L) growing in the vicinity of a phosphate fertilizer manufacturing plant near Sfax, Tunisia, were used to study the distribution of the chemical elements F, Ca, Mg, and P in the leaves and stalks. Photosynthesis and the chlorophyll content of healthy leaf parts were also investigated to determine tolerance mechanisms of this species to fluoride. The subdivision of the necrotic zone into concentric necrotic halos evidently reflects a series of plant reactions to preserve a large portion of the leaf assimilatory surface. Photosynthesis still occurred with 30 to 40% necrosis of the leaves. Preferential accumulation of F was found in the leaf margins along with a parallel accumulation of Ca. Necrosis becomes evident when a fall in Ca occurs with an excess of F. After this happens, the plant tends to maintain high Mg and P concentrations in its healthy leaf parts. At 60% leaf necrosis, F seems to be effective in reducing photosynthesis and chlorophyll content

Tolerance strategies of two Mediterranean native xerophytes under fluoride pollution in Tunisia

International audienceA field study was conducted along a fluorine gradient of soil pollution in Tunisia from Gabes, the most polluted site, to Smara, the reference site. Variations of fluoride (F) concentrations in soils were detected over one year in Gabes, Skhira and Smara. F concentrations in the aerial part of two native plant species, i.e. Erodium glaucophyllum and Rantherium suaveolens, were above the usual background concentrations. Bioaccumulation factors ranged from 0.08 to 1.3. With F concentrations in aerial parts up to 355 mg kg-1, both species may be described as Faccumulators. Both species showed an earlier vegetative growth in Gabes than in Smara. However, some difference between their strategies could be observed i.e. E. glaucophyllum shortening the period of its vegetative growth with an escape strategy and R. suaveolens decreasing its ratio of alive:dead parts potentially lowering the F toxicity by storage in dead cells. However, at a tissue level, mechanisms of tolerance were similar. Leaf section micrographs of both species showed a higher calcium accumulation in leaf midveins at Gabes than at Smara, confirming the role of calcium in plant F tolerance strategies

Screening biological traits and fluoride contents of native vegetations in arid environments to select efficiently fluoride-tolerant native plant species for in-situ phytoremediation

International audienceHigh fluoride pollution has been detected in the surrounding soils of the coastal superphosphate industries in the Gulf of Gabes (Southeast of Tunisia). A study was conducted in vicinity of factories analysing plant functional traits combined with plant fluoride accumulation and soil metal concentrations aiming to screen more efficiently native plant species tolerant to this pollution. Aerial parts of 18 plant species out of the 10 most abundant species per site were harvested on two polluted sites of Gabes and Skhira at the vicinity of the factories and on the less polluted site of Smara. Native plant species accumulated fluoride following the gradient of soil pollution. Fluoride contents of plant aerial parts ranged from 37 mg kg(-1) to 360 mg kg(-1) and five plant species were only found in the most polluted site. However these latter had low biomass and soil cover. Crossing biological traits and fluoride contents, a selection grid for potentially restorative plant species enabled the selection of three native perennials i.e. Rhanterium suaveolens, Atractylis serratuloides and, Erodium glaucophyllum as potential candidates for an in-situ phytoremediation program on arid fluoride-polluted sites. This approach may be used in other fluoride-polluted Mediterranean environments. (C) 2014 Elsevier Ltd. All rights reserved

Quantifying Food Loss and Waste in Saudi Arabia

Using the FAO model calculations proposed by Gustavsson et al. (2013) and FAO (2014), food loss and waste (FLW) is measured in Saudi Arabia with a special focus on wheat, rice, dates, poultry, vegetables, fruits, fish, and meat. Results show that the overall FLW rate is 33.1%, where the food loss rate is 14.2%, and the food waste rate is 18.9%. Acceding to the disaggregated results, we find that FLW rates are distributed as follows: 29.7% for wheat, 33.6% for rice, 21.4%, for dates 29.1% for poultry, 39.5% for vegetables, 39.6% for fruits, 33% for fish, and 31.3% for meat. The Sustainable Development Goal (SDG 12.3) target is to reduce the rates of food loss and waste by 50% in 2030, and to help achieve that goal, we employed a nonlinear optimisation simulation model with the objective function of reducing FLW by 50% over the period 2020–2030. Based on the findings achieved, recommendations are made to cover the various aspects of the whole food supply chain (FSC) and to aim at more efficiency and higher levels of productivity. Our findings have significant implications by estimating the FLW baseline indicator and providing the different stakeholders of FSC with the optimal actions to do to reduce FLW rates