Bioerosion by microbial euendoliths in benthic foraminifera from heavy metal-polluted coastal environments of Portovesme (South-Western Sardinia, Italy)

A monitoring survey of the coastal area facing the industrial area of Portoscuso-Portovesme (south-western Sardinia, Italy) revealed intense bioerosional processes. Benthic foraminifera collected at the same depth (about 2 m)but at different distances from the pollution source show extensive microbial infestation, anomalous Mg/Ca molar ratios and high levels of heavy metals in the shell associated with a decrease in foraminifera richness, population density and biodiversity with the presence of morphologically abnormal specimens. We found that carbonate dissolution induced by euendoliths is selective, depending on the Mg content and morpho-structural types of foraminiferal taxa. This study provides evidences for a connection between heavy metal dispersion, decrease in pH of the sea-water and bioerosional processes on foraminifera

Mineralogical characterization of fluorescent grossular garnet var. tsavorite from Merelani Hills, Tanzania

Tsavorite is the trade name for the green vanadium–chromium variety of grossular occurring in the Precambrian terrains in the areas of Merelani Hills (Tanzania) and Tsavo Park (Kenya) which are by far the most important source of gem grade specimens of tsavorite used for high jewellery. The tsavorite crystals from Merelani Hills exhibit a pink-red and yellow fluorescence when irradiated by common portable UV lamp, an unusual phenomenon among members of the garnet group. The electron density map calculated from the diffraction data and plotted against a grossular standard shows that an excess of negative charge is clearly pinpointed in the crystallographic site occupied by Al3+. The bulk elemental analysis shows that the most represented end-member, besides grossular, is the vanadium-bearing goldmanite garnet (3.82–4.08 mol %). The fluorometry with an excitation beam at 408 nm indicates a complex emission pattern with the most intense emissions at 701 and 716 nm and subordinately at 592 nm. The colour perception is dominated by the emission yellow band at 592 nm while the contribution of the red band modulates the colour ranging from bright orange to pink-red. The attribution of the emission at 592 nm is related to Mn2+ while the emissions at 701 and 716 nm could be related to the chromium content and/or to a possible fraction of vanadium as V2+. Because of the characteristic colour perceived under UV light, the use of a common led lamp can be useful as a diagnostic tool to easily identify tsavorite

Xenotransplantation of microencapsulated pancreatic islets contained in a vascular prosthesis: preliminary results

Porcine and human pancreatic islets were microencapsulated in an alginate-polylysine biomembrane and put in a chamber of a new vascular prosthesis composed of an inner tubing of Dacron mesh and an outer tubing of expanded polytetrafluorethylene material. The vascular prosthesis was anastomized between the iliac artery and the contralateral vein of diabetic dogs. The recipients did not receive any immunosuppressive therapy. Function of porcine and human islets was monitored by measuring serum glucose levels and human C-peptide concentrations. After transplantation, serum glucose levels were maintained at values lower than 200 mg/dl, and C-peptide concentrations were between 0.8 and 3.2 ng/ml. Injected insulin requirements decreased by 50%-60%. Four to 8 weeks after transplantation, histologic examination showed well-preserved and functioning islets in the majority of intact microcapsules. Fibrin and inflammatory cells were not observed in the chamber. These data suggest long-term survival and function of microencapsulated pancreatic islets in the vascular prosthesis. © 1991 Springer-Verlag

Response of Foraminifera to Anthropogenic Nicotine Pollution of Cigarette Butts: An Experimental Approach

The most often dispersed environmental pollutants that are released both directly and indirectly into the environment that may eventually reach aquatic ecosystems and contaminate aquatic biomes are cigarette butts (CBs). Toxicants such as nicotine, dangerous metals, total particulate matter, and recognized carcinogens can be introduced and transported via CBs into aquatic ecosystems. The examination of the effects of synthetic nicotine on three different species of cultured benthic foraminifera was the focus of this study. Three foraminiferal species from three distinct biomineralization pathways were specifically examined for viability and cellular ultrastructure, including the calcareous perforate Rosalina globularis, the calcareous imperforate Quinqueloculina spp., and the agglutinated Textularia agglutinans. The survival rate, cellular stress, and decalcification were used to assess the toxicological effects of synthetic nicotine. We were able to analyze the reaction of major macromolecules and calcium carbonate to this pollutant using FTIR (Fourier Transform Infrared) spectroscopy. High Performance Liquid Chromatography (HPLC) study was performed to increase our understanding of nicotine bioavailability in the medium culture. Different acute experiments were performed at different dates, and all indicated that synthetic nicotine is acutely hazardous to all three cultured foraminiferal taxa at lethal and sublethal concentrations. Each species responded differently depending on the type of shell biomineralization. Synthetic nicotine enhances shell decalcification and affects the composition of cytoplasmic macromolecules such as lipids and proteins, according to the FTIR spectroscopy investigations. The lipid content rose at lethal concentrations, possibly due to the creation of vesicles. The proteins signal evidences general cellular dyshomeostasis. The integration among the acute toxicity assay, synchrotron, and chemical HPLC analyses provided a valuable approach for the assessment of nicotine as a biomarker of exposure to the toxicants associated with smoking and the impact of this emerging and hazardous material on calcifying marine species

From mining wastes to mineral sources - investigating the REE-bearing occurrences in the Arburèse District (SW Sardinia)

In recent years, the search for possible sources of REE minerals in Europe involved numerous old mine areas with high volumes of mining wastes that may offer significant amounts of Critical Raw Materials (CRMs). In some cases, strong evidence of CRMs anomalous concentrations arises from environmental characterization of wastes, so that an interesting problem is that of finding their sources, i.e., the original CRMs - rich mineral phases in the residual ore. An excellent example is provided by the Arburèse district of SW Sardinia, for about 150 years a major Pb-Zn source in Italy, now an area under study for remediation of its severe environmental problems, including >10 Mt of waste deposits. The district exploited a large system (>10 km) of low-temperature polymetallic veins hosted in Lower Paleozoic siliciclastic rocks belonging to the Variscan Nappe zone, arranged in two main geometrical trends relative to the late Variscan Arbus pluton: “peripheral” and “intersecting”. Recent investigations in the Montevecchio mine area discovered high Zn (up to 2.65 wt.%) and Pb (1.23 wt.%) grades in stratified tailing materials belonging to the Sanna old processing plant. Remarkably, ICP-MS analyses on the same materials revealed total REE+ Y contents attaining about 600 ppm. XRD studies confirmed a tailing composition essentially made of gangue minerals (quartz, siderite and micas) with goethite, baryte and traces of Zn carbonates and Pb sulfates. Chondrite-normalized REE patterns are coherent with the hydrothermal character of the source: however, both the REE mineralogical host(s) in tailings and in the Montevecchio ore are still undetermined. In the search of REE-bearing phases in the ores, some relevant insights are provided by studies on the southern branch of the Arburèse system, where the veins of “peripheral” system are hosted in late Ordovician-Silurian sedimentary sequences. In this part of the district the polymetallic veins assume the character of five-elements (Ni-Co-As-Bi-Ag) veins, with a rich Ni-Co-Fe arsenide – quartz association (1) overprinted by a Zn-Pb-Cu sulfide – siderite – quartz association (2), very similar to that dominating in Montevecchio. Investigations in the Pira Inferida mine sector highlighted the presence of LREE fluorocarbonates (synchysite-Ce and bastnaesite-Ce) and phosphates (monazite) associated with rutile and apatite. LREE minerals have been detected by SEM-EDS as tiny crystals in the quartz-sericitic gangue of the Montevecchio-type (2) mineral association. The same minerals are found in millimetric aggregates in the oxide zone of the veins, sporadically reported by mineral collectors in other mine sites of the same system. Overall, these occurrences, similar to those found in other low-temperature vein systems of Sardinia (e.g., Silius vein system), appear reliable mineral REE sources for Montevecchio mine wastes; they may be therefore used as proxies for REE exploration and assessment in the district

A bacterial formula with native strains as alternative to chemical fertiliser for tomato crop

Global tomato productivity is threatened by biotic and abiotic stressors. To support and guarantee an adequate yield of tomato crops, agricultural practices have been based on the intensive use of fertilisers with negative impacts on the environment. This study presents a simple and effective strategy of functional bioaugmentation, suitable for different varieties, to replace chemical fertilisation. A tailored microbial formula composed by eight indigenous strains (including the genera Delftia, Pseudomonas, Paenarthrobacter, Phyllobacterium, Bacillus, and Acinetobacter) was developed as biofertilizer. Strains were selected from native soil for their plant growth-promoting (PGP) functions, and combined respecting the taxonomic composition of the original PGP heterotrophic community structure. The effect of the bio-fertilisation vs chemical fertilisation was tested in three successive field trials in the company greenhouse, with different tomato varieties (Camone, Oblungo, Cherry). When bio-fertilisation was applied only twice during the Camone's life cycle, tomato yield was significantly reduced (0.8 vs 2.1 kg per plant, p = 0.0003). However, monthly inoculation during plant growth led to a fruit yield comparable to that obtained with chemical fertilisers (about 1.5 kg per plant for Oblungo, and about 2 kg per plant for Cherry variety, p = 0.9999). Bio-fertilization did not significantly affect plant height; only during the last growing period of the Cherry variety, a significantly higher average plant height (p < 0.0001) was observed with chemical fertiliser. The results indicate that a knowledge-based bacterial formula and monthly inoculation during the plant growth can be a successful bio-fertilisation strategy. These findings may pave the way towards more sustainable tomato production, since farming practices are becoming increasingly crucial, in accordance with Agenda 2030 and the UE "Farm to Fork" strategy.[GRAPHICS]

Modeling groundwater flow in heterogeneous porous media with YAGMod

Modeling flow and transport in porous media requires the management of complexities related both to physical processes and to subsurface heterogeneity. A thorough approach needs a great number of spatially-distributed phenomenological parameters, which are seldom measured in the field. For instance, modeling a phreatic aquifer under high water extraction rates is very challenging, because it requires the simulation of variably-saturated flow. 3D steady groundwater flow is modeled with YAGMod (yet another groundwater flow model), a model based on a finite-difference conservative scheme and implemented in a computer code developed in Fortran90. YAGMod simulates also the presence of partially-saturated or dry cells. The proposed algorithm and other alternative methods developed to manage dry cells in the case of depleted aquifers are analyzed and compared to a simple test. Different approaches yield different solutions, among which, it is not possible to select the best one on the basis of physical arguments. A possible advantage of YAGMod is that no additional non-physical parameter is needed to overcome the numerical difficulties arising to handle drained cells. YAGMod also includes a module that allows one to identify the conductivity field for a phreatic aquifer by solving an inverse problem with the comparison model method

Isotopic Insights into Biological Regulation of Zinc in Contaminated Systems

AbstractAquatic organisms use a variety ofbiogeochemical reactions to regulate essential and non-essential trace metals. Many of these mechanisms can lead to isotopic fractionation, thus measurement of metal isotopes may yield insights into the processes by which organisms respond to metal exposure. We illustrate these concepts with two case studies, one involving an intra- and the other an extra-cellular mechanism of Zn sequestration. In the first study, the mayflyNeocloeontrianguliferwas grown in the laboratory, and fed a diet of Zn-doped diatoms at Zn levels exceeding the requirements for normal mayfly life functions. The N. trianguliferlarvae consumed the diatoms and retained their Zn isotopic signature. Upon metamorphosis, the subimago life stage lost Zn mass either in the exuvia or by excretion, and the Zn retainedwas isotopically enriched. Thus, Zn uptake is non-fractionating, but Zn regulation favors the lighter isotope. Thus the Zn remaining in the subimago was isotopically heavier. In the second study, Zn was adsorbed on the cell walls and exopolysaccharide secretions of cyanobacteria, which favored the heavier Zn isotope.Continued adsorption eventually resulted in nucleation and biomineralization of hydrozincite {Zn5(CO3)2(OH)6}. These case studies demonstrate the utility of Zn isotopes to provide insights into how aquatic insects respond to metal exposure