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The northern Adriatic Sea is a particular water system, in which the levels of nutrients are commonly low or unbalanced. In general, phosphate detection can be done with the classical molybdenum-blue method. However, the method cannot be used in oligotrophic seawater samples due to its low sensitivity and high interference problems. In this study, we present a new electrochemical method, based on the application of a plastic conductive electrode containing a molybdenum reagent embedded. The sensitivity for phosphate was high enough to detect this nutrient in oligotrophic seawater.

Phosphate detection --- Oligotrophy --- Adriatic sea --- Plastic electrode --- Electrochemical detection --- Octamolybdate

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Phosphorus is an essential plant nutrient that cannot be substituted in food production or manufactured synthetically (Johnston, 2000). Recycling of phosphorus from human excreta and urban wastewater is also currently unfavorable due to low phosphorus yields, low phosphorus concentration in the feed sources, and high energy and reactant consumption during processing to produce sludge-based fertilizer (Pradel & Aissani, 2019). Therefore, phosphate rock remains the only economical source of the phosphorus required to manufacture phosphate-containing chemical fertilizers, which are needed to improve crop yields, thereby feeding the growing world population. In 2019, 240 million tonnes of phosphate rock were mined worldwide, and more than 90% of the mined phosphate rock was used to manufacture different types of fertilizer and animal feeds (US Geological Survey, 2019).&#13;To manufacture fertilizer, phosphate rock is first beneficiated to reduce the content of calcium, magnesium, iron, aluminum, silica, fluorine, chlorine, sodium, potassium, heavy metal impurities. The phosphate industry generally requires a phosphate rock concentrate containing: P2O5 > 30 wt.%, CaO/P2O5 ratio smaller than 1.6, and MgO < 1 wt.% (Sis & Chander, 2003). After beneficiation, the phosphate rock concentrate is reacted with sulfuric acid to produce single superphosphate fertilizer directly or wet-process phosphoric acid, which is a critical ingredient in the manufacture of different types of fertilizers and animal feed supplements. According to Kelahan et al. (2019), upon entering the phosphoric acid wet process, phosphate rock impurities dissolve releasing ions, which cause numerous process and final product-related problems. Therefore, the control of phosphate rock impurities going into the wet process of phosphoric acid production is critical.&#13;This study aimed to identify, sample, and subject the different ore types found in the south and north orebody of the Dorowa carbonatite complex in Zimbabwe to flotation test to determine which ore types could yield phosphate concentrates with Fe2O3 and CO2 contents greater than 2.14% and 2% respectively. Dorowa Minerals Limited currently exports phosphate rock concentrate to a phosphate chemistry leader called Prayon in Belgium. The phosphate concentrates exported to Prayon are required to contain; P2O5 > 30 wt.%, Fe2O3 < 2.14 wt.% and CO2 < 2 wt.%. Historical Dorowa phosphate concentrates exported to Prayon satisfy the Fe2O3 and CO2 restrictions imposed on the concentrate. However, variations in the ore types fed into the processing plant at Dorowa can result in the set restrictions not being met. &#13;Therefore, the different ore types found in the south and north orebody were subjected to batch flotation tests with the fatty acid and alkyl succinamate collectors currently used in the Dorowa Minerals Limited processing plant. A particle size by size analysis of key flotation streams was conducted to establish the optimum P2O5 grade liberation size range, the size range at which P2O5 is lost to the tailings, and the size ranges in which iron impurities contaminate the Aero 845, Betacol and final concentrate. A full chemistry determination of the process water used at Dorowa was conducted, and seasonal variations in water quality were also established.

Phosphate rock, impurities, fertilizer, phosphoric acid, ore types --- Ingénierie, informatique & technologie > Géologie, ingénierie du pétrole & des mines

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This book collects the peer-reviewed contributions accepted for the publication in the Special Issue “Advances in In Situ Biological and Chemical Groundwater Treatment” of the MDPI journal Water. As such, the contributions refer to a variety of widespread pollutants (chlorinated ethenes, chlorinated phenols, chromium, copper, nickel, and arsenic phenols) and new remediation approaches (bioremediation, bioelectrochemical systems, and sorption), covering lab and field studies.

Research & information: general --- microplastic --- bioplastic --- chlorinated phenols --- sorption --- kinetics --- matrix effect --- arsenic --- phosphate --- competitive surface complexes --- release --- mobility --- remediation --- magnetite nanoparticles --- onion peel --- corn silk --- adsorption --- groundwater --- chlorinated solvents --- biological reductive dechlorination --- aerobic oxidation --- qPCR --- ethenotrophs --- methanotrophs --- bioelectrochemical systems (BESs) --- hexavalent chromium --- electrobioremediation --- groundwater treatment --- heavy metals --- carbon nanotubes --- adsorption mechanism

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Diagenesis refers to changes taking place in sediments after deposition. In a theoretical treatment of early diagenesis, Robert Berner shows how a rigorous development of the mathematical modeling of diagenetic processes can be useful to the understanding and interpretation of both experimental and field observations. His book is unique in that the models are based on quantitative rate expressions, in contrast to the qualitative descriptions that have dominated the field.In the opening chapters, the author develops the mathematical theory of early diagenesis, introducing a general diagenetic equation and discussing it in terms of each major diagenetic process. Included are the derivations of basic rate equations for diffusion, compaction, pore-water flow, burial advection, bioturbation, adsorption, radioactive decay, and especially chemical and biochemical reactions. Drawing on examples from the recent literature on continental-margin, pelagic, and non-marine sediments, he then illustrates the power of these diagenetic models in the study of such deposits.The book is intended not only for earth scientists studying sediments and sedimentary rocks, but also for researchers in fields such as radioactive waste disposal, petroleum and economic geology, environmental pollution, and sea-floor engineering.

Diagenesis. --- G-type kinetics. --- Michaelis-Menten kinetics. --- adsorption. --- bacterial processes. --- bioturbation. --- cementation. --- denitriflcation. --- electrical double layer. --- formation factor. --- geopolymers. --- hypersaline sediments. --- ion exchange. --- lake sediments. --- manganese reduction. --- methane formation. --- nitrogen diagenesis. --- organic matter decomposition. --- phosphate diagenesis. --- radioisotope diagenesis. --- salinity fluctuations. --- silica dissolution. --- useful porosity. --- zero point of charge.

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Crystallography remains, for mineralogy, one of the main sources of information on natural crystalline substances. A description of mineral species shape is carried out according to the principles of geometric crystallography; the crystal structure of minerals is determined using X-ray crystallography techniques, and physical crystallography approaches allow one to evaluate various properties of minerals, etc. However, the reverse comparison should not be forgotten as well: the crystallography science, in its current form, was born in the course of mineralogical research, long before preparative chemistry received such extensive development. It is worth noting that, even today, investigations of crystallographic characteristics of minerals regularly open up new horizons in materials science, because the possibilities of nature (fascinating chemical diversity; great variation of thermodynamic parameters; and, of course, almost endless processing time) are still not available for reproduction in any of the world's laboratories. This Special Issue is devoted to mineralogical crystallography, the oldest branch of crystallographic science, and aims to combine important surveys covering topics indicated in the keywords below.

Research & information: general --- galenobismutite --- high pressure --- single-crystal X-ray synchrotron diffraction --- equation of state --- calcium ferrite structure type --- lone electron pair --- vaterite --- calcium carbonate --- polymorph --- precipitation --- synthesis --- carbonation --- pathogen crystallization --- biomimetic synthesis --- renal stone --- calcium oxalate --- apatite --- brushite --- struvite --- octocalcium phosphate --- whitlockite --- Escherichia coli --- Klebsiella pneumoniae --- Pseudomonas aeruginosa --- Staphylococcus aureus --- uranyl --- selenite --- selenate --- crystal structure --- topology --- structural complexity --- demesmaekerite --- guillemenite --- haynesite --- coesite --- high-temperature Raman --- FTIR spectrum --- single crystal structure --- isobaric Grüneisen parameters --- OH-stretching modes --- strontium oxalate --- solid solutions --- ionic substitutions --- weddellite --- whewellite --- X-ray powder diffraction --- scanning electron microscopy --- EDX spectroscopy --- hydroxy-hydrate --- sulfate --- cesium --- schoepite --- krasnoshteinite --- zeolite-like borate --- hydrous aluminum chloroborate --- new mineral --- microporous crystalline material --- evaporitic salt rock --- Verkhnekamskoe potassium salt deposit --- Perm Krai --- anatomy --- Cactaceae --- oxalate --- silica --- stem --- stanfieldite --- phosphate --- merrillite --- meteorite --- pallasite --- mesosiderite --- luminophore --- bioceramics --- powder diffraction --- Raman spectroscopy --- Kamchatka --- hot springs --- pyrite --- complexity of crystal habits --- Mars --- mineral --- crystallography --- crystal chemistry --- X-ray diffraction --- crystal growth --- mineral evolution