Unveiling the organic nature of phosphogypsum foam: Insights into formation dynamics, pollution load, and contribution to marine pollution in the Southern Mediterranean Sea.

The foamability of dissolved phosphogypsum from the phosphate fertilizer factories of Gabes (SE Tunisia) is a spectacular phenomenon that has not yet been thoroughly studied. The main objective of this research was to investigate the organic properties of phosphogypsum foam (PGF) to understand its formation process, determine the origin of its enhanced radiochemical contaminants load, and identify its role in pollutants dispersion in marine environment of the Southern Mediterranean Sea. This study identified PGF as an unnatural, surfactant-stabilized, and ephemeral aqueous foam. PGF-forming process comprises three main steps: (i) formation (through phosphogypsum dissolution), (ii) stabilization (facilitated by organic surfactants and gypsum crystals), and (iii) destabilization (geochemical (involving the dissolution of the PGF skeleton gypsum) and/or mechanical (influenced by wind and wave action)). The amphiphilic nature of PGF organic matter and the presence of specific organic groups are responsible for its high toxic contaminants load. PGF contributes, through its elevated pollutants content and its ability to migrate far from its source, to the marine dispersion of industrial toxic radiochemical contaminants. It is therefore recommended to mitigate the environmental and health risks associated with PGF, including banning the discharge of untreated phosphogypsum and other industrial wastes into the coastal environment of Gabes.

Slab melting boosts the mantle wedge contribution to Li-rich magmas.

The lithium cycling in the supra-subduction mantle wedge is crucial for understanding the generation of Li-rich magmas that may potentially source ore deposition in continental arcs. Here, we look from the mantle source perspective at the geological processes controlling the Li mobility in convergent margins, by characterizing a set of sub-arc mantle xenoliths from the southern Andes (Coyhaique, western Patagonia). The mineral trace element signatures and oxygen fugacity estimates (FMQ > + 3) in some of these peridotite xenoliths record the interaction with arc magmas enriched in fluid-mobile elements originally scavenged by slab dehydration. This subduction-related metasomatism was poorly effective on enhancing the Li inventory of the sub-arc lithospheric mantle, underpinning the inefficiency of slab-derived fluids on mobilizing Li through the mantle wedge. However, major and trace element compositions of mantle minerals in other xenoliths also record transient thermal and chemical anomalies associated with the percolation of slab window-related magmas, which exhibit an "adakite"-type geochemical fingerprint inherited by slab-derived melts produced during ridge subduction and slab window opening event. As these melts percolated through the shallow (7.2-16.8 kbar) and hot (952-1054 °C) lithospheric mantle wedge, they promoted the crystallization of metasomatic clinopyroxene having exceptionally high Li abundances (6-15 ppm). Numerical modeling shows that low degrees (< 10%) of partial melting of this Li-rich and fertile sub-arc lithospheric mantle generates primitive melts having two-fold Li enrichment (~13 ppm) compared with average subduction-zone basalts. Prolonged fractional crystallization of these melts produces extremely Li-enriched silicic rocks, which may stoke the Li inventory of mineralizing fluids in the shallow crust.

PET plastics as a Trojan horse for radionuclides.

Mismanaged plastic waste interacts with secondary environmental pollutants, potentially aggravating their impact on ecosystems and human health. Here we characterized the natural and artificial radionuclides in polyethylene terephthalate (PET) bottles collected from the industrial littoral discharge of a phosphate fertilizer plant. The activity concentrations in littered bottles ranged from 0.47 (208Tl) to 12.70 Bq·kg-1 (226Ra), with a mean value of 5.30 Bq·kg-1. All the human health risk assessment indices (annual intake, annual effective dose, and excess lifetime cancer risk) estimated for radionuclides associated with ingestion and inhalation of microplastics were below international safety limits. Our results demonstrated that PET can be loaded with natural and artificial radionuclides, and potentially act as a carrier to transfer radionuclides to humans, posing a new potential health risk. Increased use, mismanagement and fragmentation of plastic waste, and continued interaction of plastic waste with radioelements may lead to enhanced radiation exposure in the future.

Economic losses related to the reduction of Posidonia ecosystem services in the Gulf of Gabes (Southern Mediterranean Sea).

In the early XXth century, the Gulf of Gabes in SE Tunisia used to host the most extended Posidonia oceanica seagrass beds in the Mediterranean basin and was a highly productive hotspot of benthic species. Since the 70's, >500 million t of wet toxic phosphogypsum discharges from a fertilizer industrial complex have led to the gradual loss of ∼90 % of its initial surface. This drastic shrinkage is accompanied by significant value losses originated from the direct and indirect-use services of which the most important ones are small scale fisheries and carbon storage function. Using market valuations of a number of services we estimate economic losses at 105 million € in 2014 (∼915€/ha), i.e., around 115 % of the added value of the gabesian fertilizer factories for the same year. Value losses should increase in the near future in relation with the COP26 agreements which boosted the open carbon credit market. Without actions to reduce negative production externalities caused by the fertilizer industry in the Gulf of Gabes it would not be possible to recover Posidonia ecosystems in this region leading to further economic, ecologic, and cultural losses.

Rare earth elements characterization associated to the phosphate fertilizer plants of Gabes (Tunisia, Central Mediterranean Sea): Geochemical properties and behavior, related economic losses, and potential hazards.

This is the first study on the behavior and industrial fluxes of rare earth elements (REE) in the coastal fertilizer plants of Gabes (south-eastern Tunisia), the economic losses related to their wastes, and their environmental and human health hazards. The concentrations of 16 REE were assessed in phosphate rock (PR), phosphogypsum (PG) and phosphogypsum foam (PGF) samples, collected from Gabes plants. REE concentrations ranged from 0.23 (for Sc in PG) to 309.33 mg kg-1 (for Ce in PGF). Ce was the most abundant in the three matrices, with concentrations ranging between 80.40 (in PG) and 309.33 mg kg-1 (in PGF). PGF was the most enriched with REE (1075.32 mg kg-1). The annual flow of REE from the fertilizer factories to the marine environment may reach 1523.67 t. The economic losses related to the discharge of phosphogypsum REE in the Gulf of Gabes (GG) was estimated at ~58 million US$ y-1. The potential hazards of discharged REE on the local environment and human health were also evaluated and discussed. These findings show the need for the development of a new industry exploiting REE from phosphogypsum wastes (short term) and phosphate ores (long term) which should lead to reduce its high environmental and human health footprint and to potential economic gains.

Surface sediment enrichment with trace metals in a heavily human-impacted lagoon (Bizerte Lagoon, Southern Mediterranean Sea): Spatial distribution, ecological risk assessment, and implications for environmental protection.

Although several studies previously assessed the contents of trace metals in the sediments of the heavily human-impacted lagoon of Bizerte (northern Tunisia), multi-analytical approaches have not been, so far, used to assess the ecological risks in this water body. This study attempts to provide a comprehensive ecological risk assessment related to the enrichment of the lagoon sediments with seven metals (As, Cd, Cr, Cu, Hg, Pb, and Zn). Significant spatial variations were found in the metal concentrations in sediments, in relation to the degree of coastal human activities and hydrodynamics. This was confirmed with the results of the three pollution indices, Cf, PLI, and Igeo. Concordant results were found with most of the indices used to assess the ecological risks (PERI, PEL, ERL, ERM, M-ERM-Q, TU), indicating higher risks in the southern part of the lagoon. These findings can help to improve the environmental management plan of the socio-economic important lagoon of Bizerte.

Economic impact of human-induced shrinkage of Posidonia oceanica meadows on coastal fisheries in the Gabes Gulf (Tunisia, Southern Mediterranean Sea).

In early XXth century, the Gulf of Gabes (SE Tunisia) used to host the most extended Posidonia oceanica seagrass beds in the Mediterranean Sea, and a highly productive hotspot of benthic/demersal biodiversity. Sponge harvesting and seabed trawling provoked a first step of seagrass degradation. Subsequently, phosphogypsum releases from Gabes Industrial Complex, since mid-1970s, accelerated the decline of the remaining patches. A sharp reduction of coastal fisheries landings took place with the establishment of the last industrial plant units in 1985. The decrease in coastal commercial species landings was found to be directly correlated with P. oceanica decline. The trophic web system switched from a 'benthic-dominated' to a 'pelagic-dominated' system. The economic loss related to coastal fisheries was estimated at ~60 million € in 2014 and the 1990-2014 cumulated loss exceeded 750 million €. This first economic valuation of the only direct-use consumptive value of the coastal fishing service provided by P. oceanica in Gabes Gulf is a first step towards the assessment of the environmental cost of the negative externalities caused by the local phosphate industry. It may be used as a preliminary decision-making aid to consider alternative industrial solutions.

Natural radioactivity and radiation hazard assessment of industrial wastes from the coastal phosphate treatment plants of Gabes (Tunisia, Southern Mediterranean Sea).

This work is a first contribution to the knowledge of natural radionuclides (226Ra, 238U, 40K, and 232Th) activities in phosphate rock (NORM), phosphogypsum, and phosphogypsum foam (TENORM) from the coastal fertilizer plants of Gabes (Southeastern Tunisia) and the assessment of their radiation hazards on human health and the surrounding environment. In the three studied materials, activities were found to be in the range of 35.4 (40K)-375.1 (226Ra), 10.0 (40K)-220.2 (226Ra), and 79.2 (232Th)-1168.6 Bq kg-1 (226Ra), respectively. Considering the studied radionuclides and materials, the corresponding decreasing activity orders were found to be 226Ra > 238U > 40K > 232Th and PGF > PR > PG, respectively. All human health hazard indices exceeded the worldwide recommended safety limits, which show that the workers in Gabes phosphate fertilizer plants as well as the neighboring human community may potentially be exposed to significant radiation, which may cause several diseases and malformations. It is therefore recommended to avoid and/or reduce the potential fertilizer industry radioactive impact in the area.

Plume-subduction interaction forms large auriferous provinces.

Gold enrichment at the crustal or mantle source has been proposed as a key ingredient in the production of giant gold deposits and districts. However, the lithospheric-scale processes controlling gold endowment in a given metallogenic province remain unclear. Here we provide the first direct evidence of native gold in the mantle beneath the Deseado Massif in Patagonia that links an enriched mantle source to the occurrence of a large auriferous province in the overlying crust. A precursor stage of mantle refertilisation by plume-derived melts generated a gold-rich mantle source during the Early Jurassic. The interplay of this enriched mantle domain and subduction-related fluids released during the Middle-Late Jurassic resulted in optimal conditions to produce the ore-forming magmas that generated the gold deposits. Our study highlights that refertilisation of the subcontinental lithospheric mantle is a key factor in forming large metallogenic provinces in the Earth's crust, thus providing an alternative view to current crust-related enrichment models.The lithospheric controls on giant gold deposits remain unclear. Here, the authors show evidence for native gold in the mantle from the Deseado Massif in Patagonia demonstrating that refertilisation of the lithospheric mantle is key in forming metallogenic provinces.

Alternativas para una riqueza olvidada: reciclaje de desechos sólidos en zonas marginales, el caso de la ciudad de El Alto

Debido al crecimiento de la población y el problema que representa los residuos sólidos (basuras) con respecto al barrido de vías y áreas públicas, recolección, transporte y disposición final de los residuos, se ha visto por conveniente implantar al sistema SEMDES el año 1980. Para implementar este servicio, se comenzó con el servicio de recolección domiciliaria en las zonas más importantes que se hallan en la zona sur y norte. El objetivo del reciclaje de los residuos sólidos es el de conocer la producción per cápita, composición física, densidad en recipientes, densidad suelta, densidad en carros recolectores, densidad descargada en relleno, densidad recién rellenada, densidad estabilizada, humedad promedio y poder calorífico de los residuos sólidos en la zona de El Alto

El riesgo de ser menor: estrategias de prevención integral de la marginalidad en la población infanto-juvenil en alto riesgo

El presente estudio El riesgo de ser menor, realizado por ENDA-Bolivia organización no gubernamental que propone una alternativa educativa, laboral y de atención primaria en favor del menor en riesgo, plantea una reflexión de la realidad del menor trabajador y de la calle en la ciudad de El Alto a través de un modelo comunitario válido para grupos humanos en circunstancias tan difíciles como son los beneficiarios del programa de prevención integral del uso indebido de drogas en la población infanto-juvenil de la ciudad de El Alto

El riesgo de ser menor

El presente estudio "EL RIESGO DE SER MENOR", realizado por ENDA-BOLIVIA organización no gubernamental que propone una alternativa, laboral y de atención primaria en favor del Menor en riesgo, plantea una reflexión de la realidad del Menor Trabajador y de la calle en la ciudad de El Alto a través de un modelo comunitario válido para grupos humanos en circunstancias tan difíciles como son los beneficiarios del Programa Alternativo de Prevención Integral de la marginalidad en la Población Infanto-Juvenil Urbano en alto riesgo de la ciudad de El Alto

Alternativas para una riqueza olvidada: reciclaje de desechos sólidos en zonas marginales, el caso de la ciudad de El Alto

En materia de desarrollo de la naciente ciudad de El Alto se ha dicho mucho y hecho poco, no obstante existiendo innumerables problemas tanto a nivel salud, educación como infraestructura básica y otros. Durante años El Alto fue considerado como un otro barrio marginal mucho más pobre, mucho más abandonado y mucho más misterioso que cualquier otro al margen de esta gran Ciudad de La Paz. Es tiempo que la Ciudad de El Alto sea lo que justamente una nueva ciudad se merece. Los problemas son tan desmedidos y diversos, siendo los desafíos tan insospechables como apasionantes, que realmente no bastan los esfuerzos como para combatir las dificultades inherentes a las condiciones cotidianas de esta ciudad altiplánica. En este sentido el Programa de Reciclaje de Desechos Sólidos diseñado por la ONG ENDA-BOLIVIA es la manifestación responsable de nuevas acciones generadoras de trabajo para los niños y jóvenes en circunstancias especialmente difíciles y la contribución efectiva a un significativo mejoramiento ambiental de nuestra urbe así como una dinamización de un sector económico a menudo olvidado

El riesgo de ser menor

Los niños de la calle son, sin duda, una herida abierta que debe sobrecogernos a todos y conducirnos al empeño de forjar un mejor destino para el país a partir de darles a los niños un presente digno y un porvenir promisorio.