Chemical elements in sediments and in bivalve mollusks from estuarine regions in the south of Bahia State, northeast Brazil

Estuaries receive daily inputs of chemical elements which can impact the quality of water and sediment, as well as the health of biota. In addition to the sediment, bivalve mollusks have been used in the chemical monitoring of these systems. This study investigated the presence and contents of As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn in superficial sediment and in bivalves (Crassostrea gasar, C. rhizophorae and Mytella guyanensis) from estuaries in the south / extreme south of Bahia State, northeast Brazil. The samples were evaluated with inductively coupled plasma optical emission spectrometry (ICP-OES, Varian 710). Except for Cd, all other elements were found in the samples, being that Co was exclusive in the sediment. The estuaries equivalent to sampling stations #1 - Valença, #2 - Taperoá, #3 - Ilhéus and #4 - Belmonte showed levels of metals compatibles with those established by the Brazilian legislation, however, the #5 - Santa Cruz Cabrália, in addition to the presence of As, presented a high level of Pb and Cu in C. gasar, which was attributed to the impacts of nautical activities in that locality.

Sulfate-dependant microbially induced corrosion of mild steel in the deep sea: a 10-year microbiome study

Background Metal corrosion in seawater has been extensively studied in surface and shallow waters. However, infrastructure is increasingly being installed in deep-sea environments, where extremes of temperature, salinity, and high hydrostatic pressure increase the costs and logistical challenges associated with monitoring corrosion. Moreover, there is currently only a rudimentary understanding of the role of microbially induced corrosion, which has rarely been studied in the deep-sea. We report here an integrative study of the biofilms growing on the surface of corroding mooring chain links that had been deployed for 10 years at ~2 km depth and developed a model of microbially induced corrosion based on flux-balance analysis. Methods We used optical emission spectrometry to analyze the chemical composition of the mooring chain and energy-dispersive X-ray spectrometry coupled with scanning electron microscopy to identify corrosion products and ultrastructural features. The taxonomic structure of the microbiome was determined using shotgun metagenomics and was confirmed by 16S amplicon analysis and quantitative PCR of the dsrB gene. The functional capacity was further analyzed by generating binned, genomic assemblies and performing flux-balance analysis on the metabolism of the dominant taxa. Results The surface of the chain links showed intensive and localized corrosion with structural features typical of microbially induced corrosion. The microbiome on the links differed considerably from that of the surrounding sediment, suggesting selection for specific metal-corroding biofilms dominated by sulfur-cycling bacteria. The core metabolism of the microbiome was reconstructed to generate a mechanistic model that combines biotic and abiotic corrosion. Based on this metabolic model, we propose that sulfate reduction and sulfur disproportionation might play key roles in deep-sea corrosion. Conclusions The corrosion rate observed was higher than what could be expected from abiotic corrosion mechanisms under these environmental conditions. High corrosion rate and the form of corrosion (deep pitting) suggest that the corrosion of the chain links was driven by both abiotic and biotic processes. We posit that the corrosion is driven by deep-sea sulfur-cycling microorganisms which may gain energy by accelerating the reaction between metallic iron and elemental sulfur. The results of this field study provide important new insights on the ecophysiology of the corrosion process in the deep sea.

A Baseline Survey of The Geochemical Characteristics of the Arctic Soils of Alexandra Land Within the Franz Josef Land Archipelago (Russia)

The composition of soils and their parent materials were studied within one of the most northern land areas of the world – the island of Alexandra Land of the Franz Josef Land archipelago. Contents of 65 trace and major elements were determined using atomic emission spectrometry (ICP-AES) и inductively coupled plasma spectrometry (ICP-MS). Other analyzed characteristics included soil pH, particle-size distribution and contents of carbon and nitrogen. The mineralogical composition of rocks was determined in thin sections. The studied soils were formed on basalts with high contents of MgO, Fe2O3, TiO2, Сu, Co, V, Ni, Cr, Zn, and low contents of Pb and Hg. The composition of soils was generally similar to that of the bedrock. The median concentrations (mg kg-1) of trace elements in the soils were as follows: Cu - 160, Zn - 101, Ni - 74, Pb - 2.9, Cd - 0.14, and Hg - 0.031. The bedrock had an alkaline pH, whereas the soil pH ranged from weakly acid to alkaline. The textural class of the soils predominantly corresponded to sandy loam. The contents of clay and silt increased with depth due to the migration of these fractions with groundwater. The concentrations of ecologically hazardous Hg and Pb were slightly increased in the upper layer of soils and correlated with carbon contents, which was indicative of bioconcentration processes.

Zinc- and Copper-Loaded Nanosponges from Cellulose Nanofibers Hydrogels: New Heterogeneous Catalysts for the Synthesis of Aromatic Acetals

Herein we report the synthesis of cellulose-based metal-loaded nano-sponges and their application as heterogeneous catalysts in organic synthesis. First, the combination in water solution of TEMPO-oxidized cellulose nanofibers (TOCNF) with branched polyethyleneimine (bPEI) and citric acid (CA), and the thermal treatment of the resulting hydrogel, leads to the synthesis of an eco-safe micro- and nano-porous cellulose nano-sponge (CNS). Subsequently, by exploiting the metal chelation characteristics of CNS, already extensively investigated in the field of environmental decontamination, this material is successfully loaded with Cu (II) or Zn (II) metal ions. Efficiency and homogeneity of metal-loading is confirmed by scanning electron microscopy (SEM) analysis with an energy dispersive X-ray spectroscopy (EDS) detector and by inductively coupled plasma-optical emission spectrometry (ICP-OES) analysis. The resulting materials perform superbly as heterogeneous catalysts for promoting the reaction between aromatic aldehydes and alcohols in the synthesis of aromatic acetals, which play a fundamental role as intermediates in organic synthesis. Optimized conditions allow one to obtain conversions higher than 90% and almost complete selectivity toward acetal products, minimizing, and in some cases eliminating, the formation of carboxylic acid by-products. ICP-OES analysis of the reaction medium allows one to exclude any possible metal-ion release, confirming that catalysis undergoes under heterogeneous conditions. The new metal-loaded CNS can be re-used and recycled five times without losing their catalytic activity.

Influence of Al2O3 Coatings on HF Induced Transition Metal Dissolution from Lithium-Ion Cathodes

Transition metal (TM) dissolution from oxide cathode materials is a major challenge limiting the performance of modern Li-ion batteries. Coating the cathode materials with thin protective layers has proved to be a successful strategy to prolong their lifetime. Yet, there is a lack of fundamental understanding of the working mechanisms of the coating. Herein, the effect of the most commonly employed coating material, Al2O3, on suppressing hydrofluoric acid(HF)-induced TM dissolution from two state-of-the-art cathode materials, LiMn2O4 and LiNi0.8Mn0.1Co0.1O2, is investigated. Karl Fischer titration, fluorine selective probe and inductively coupled plasma optical emission spectrometry are coupled to determine evolution of H2O, HF and TM concentrations, respectively, when the active materials come in contact with the aged electrolyte. The coating reduces the extent of TM dissolution, in part due to the ability of Al2O3 to scavenge HF and reduce the acidity of the electrolyte. Delithiation of the cathode materials, however, increase the extent of TM dissolution, likely because of the higher vulnerability of surface TMs in +IV oxidation state towards HF attack. In conclusion, the current study evidences the important role of acid-base reactions in governing TM dissolution in Li-ion batteries and shows that coatings protect the cathode towards an acidic electrolyte.

Levels and health risk assessment of pesticides and metals in Lycium barbarum L. from different sources in Ningxia, China

The berries of Lycium barbarum L. (Goji) are widely used as a Chinese traditional herbal medicine and functional food because of their reported beneficial pharmacological effects. However, there are reports of Goji berries being contaminated by chemical residues that could pose a hazard to humans. In this study, samples of L. barbarum L. berries were collected from plantations in a genuine production area and supermarkets in Ningxia, China. The major hazardous chemicals, including pesticides (dichlorvos, omethoate, cypermethrin, fenvalerate, malathion, and deltamethrin) and metals (lead (Pb), cadmium (Cd), copper (Cu), nickel (Ni), zinc (Zn), and arsenic (As)), were quantified by gas chromatography and inductively coupled plasma-optical emission spectrometry. In addition, associated daily exposures and health risks were determined using deterministic and probabilistic assessments. The levels of five pesticides from the plantation samples were considerably lower than the maximum residue limits; only dichlorvos was detected in the supermarket samples, and deltamethrin was not detected in any samples. Cu, Zn, As, Pb, Ni and Cd were detected in samples from both sources. The hazard quotient values of individual hazardous chemicals and the hazard index of combined hazardous chemicals were considerably less than 1, indicating the absence of a non-carcinogenic effect of hazardous chemical exposures through Goji berry consumption. The R value of As was much less than 10–6, which shows that consumption of the Goji berries had no obvious carcinogenic risks. The potentially harmful effects of the L. barbarum L. are more likely from berries obtained from plantations than those from supermarkets, and metal exposure is more dangerous than pesticide exposure. However, on the basis of our analysis, no population would be exposed hazardous chemicals exceeding existing standards, and the factors most affecting the health risk were exposure frequency and As content.

The Effects and Mechanisms of Action of TC-G 1008, GPR39 Agonist, in Animal Models of Seizures and Epilepsy

Background and purpose: The G-protein coupled receptor 39 (GPR39) may be activated by zinc ions. Activation of GPR39 was suggested as a novel pharmacological strategy for treating seizures. Experimental approach: We utilized a specific agonist of GPR39, TC-G 1008, and the nonspecific agonist, zinc chloride and a variety of models of acute seizures or a chronic model of epilepsy which were induced in non-genetically modified mice, GPR39 knockout mice or in zebrafish larvae. We examined total serum zinc (by Inductively Coupled Plasma Optical Emission Spectrometry) as well as intracellular zinc ([Zn2+]I) (by Zinpyr-1 staining) concentrations and the expression of selected proteins (by Western blot) which are associated with GPR39 signaling in the hippocampus. Key results: Liquid chromatography tandem mass spectrometry analysis showed that TC-G 1008 is brain penetrant. TC-G 1008 decreased the seizure threshold in the maximal electroshock seizure (MES) threshold test, but it increased the seizure threshold in the 6-Hz induced seizure threshold test. The behavioral effects of TC-G 1008 and MES or 6-Hz seizure were accompanied by alterations in hippocampal [Zn2+]I. TC-G 1008 increased the mean duration of EEG discharges in response to pentylenetetrazole (PTZ) in zebrafish larvae and facilitated the development of PTZ kindling in mice. Using GPR39 knockout mouse line, generated by the CRISPR-Cas-9 method, we showed that GPR39 is a target for TC-G 1008 regarding PTZ-induced epileptogenesis. Conclusion and implications: Our in vivo data obtained using TC-G 1008 generally argue against GPR39 activation as a therapeutic strategy for alleviating seizures/epilepsy.

A Comprehensive Review of Minerals, Trace Elements, and Heavy Metals in Saffron

Saffron is one of the most expensive spices in the world, and its popularity as a tasty food additive is spreading rapidly through many cultures and cuisines. Minerals and heavy metals are minor components found in saffron, which play a key role in the identification of the geographical origin, quality control, and food traceability, while they also affect human health. The chemical elements in saffron are measured using various analytical methods, such as techniques based on spectrometry or spectroscopy, including atomic emission spectrometry, atomic absorption spectrometry, inductively coupled plasma optical emission spectrometry, and inductively coupled plasma mass spectrometry. The present study aimed to review the published articles about heavy metals and minerals in saffron across the world. To date, 64 chemical elements have been found in different types of saffron, which could be divided into three groups of macro-elements, trace elements, and heavy metals (trace elements with a lower gravity/greater than five times that of water and other inorganic sources). Furthermore, the chemical elements in the saffron samples of different countries have a wide range of concentrations. These differences may be affected by geographical condition such as physicochemical properties of the soil, weather and other environmental conditions like saffron cultivation and its genotype.