Search

The primary objective of this study was to measure the risk of return Emergency Department (ED) visits in patients presenting to the ED with a diagnosis of substance-induced psychosis. Secondary objectives included: (1) describing the characteristics of patients returning within 30 days to the ED with substance-induced psychosis, and (2) identifying risk factors associated with such ED return.At two urban sites from January 1, 2018 to December 31, 2019, we included consecutive patients presenting to the ED with substance-induced psychosis defined by their ED discharge diagnosis of psychosis and clinical evidence of substance use. We described ED resources utilized by this patient population including ED time and disposition then subsequently described return visits within 30 days and characteristics among those patients who returned.We identified 611 unique patients presenting with substance-induced psychosis, with 813 total ED visits. The median age was 35 years (IQR 28-45), 71.4% (n = 436) were male, and 44.8% (n = 274) were homeless. The median ED length of stay was 619 min (IQR 313-898), and 48.4% (n = 296) were admitted to hospital. Forty percent of patients (n = 237) returned to the ED within 30 days of the index substance-induced psychosis visit, 116 (18.9%) returning more than once. Of these return visits, 74 (31.2%) were for recurrent substance-induced psychosis. Younger age, female gender, no opioid use, and no prior history of bipolar disorder were identified as common characteristics among those returning to the ED with substance-induced psychosis.In ED patients with substance-induced psychosis, nearly half of all patients were admitted to hospital, 40% had a 30 days return ED visit, and one-third of those were for substance-induced psychosis. We identified clinically relevant factors common to those returning with recurrent substance-induced psychosis.RéSUMé: OBJECTIFS: L'objectif principal de cette étude était de mesurer le risque de retour aux urgences chez les patients se présentant aux urgences avec un diagnostic de psychose induite par une substance. Les objectifs secondaires comprenaient : 1) décrire les caractéristiques des patients qui retournent aux urgences dans les 30 jours avec une psychose induite par la substance, et 2) déterminer les facteurs de risque associés à ce retour aux urgences. MéTHODES: Dans deux sites urbains, du 1er janvier 2018 au 31 décembre 2019, nous avons inclus des patients consécutifs se présentant aux urgences avec une psychose induite par une substance, définie par leur diagnostic de psychose à la sortie des urgences et des preuves cliniques de consommation de substances. Nous avons décrit les ressources des urgences utilisées par cette population de patients, notamment le temps passé aux urgences et les dispositions prises, puis nous avons décrit les visites de retour dans les 30 jours et les caractéristiques des patients qui sont revenus. RéSULTATS: Nous avons identifié 611 patients uniques présentant une psychose induite par une substance, avec un total de 813 visites aux urgences. L'âge médian était de 35 ans (IQR 28-45), 71,4 % (n = 436) étaient des hommes et 44,8 % (n = 274) étaient sans domicile fixe. La durée médiane du séjour aux urgences était de 619 minutes (IQR 313-898), et 48,4 % (n = 296) ont été hospitalisés. Quarante pour cent des patients (n = 237) sont retournés aux urgences dans les 30 jours suivant la visite de référence pour une psychose due à une substance, 116 (18,9 %) y étant retournés plus d'une fois. Parmi ces visites de retour, 74 (31,2 %) concernaient une psychose récurrente induite par une substance. Un âge plus jeune, le sexe féminin, l'absence de consommation d'opioïdes et d'antécédents de troubles bipolaires ont été identifiés comme des caractéristiques communes chez les personnes revenant aux urgences pour une psychose induite par une substance. CONCLUSIONS: Chez les patients des urgences souffrant de psychose due à une substance, près de la moitié des patients ont été hospitalisés, 40 % sont revenus aux urgences dans les 30 jours, dont un tiers pour une psychose due à une substance. Nous avons identifié des facteurs cliniquement pertinents communs à ceux qui reviennent avec une psychose récurrente induite par une substance.

Background. Power law distributions have been found in many contexts, both natural and social. This study examines one way of applying the power law distribution to characterize the breadth and accessibility of library collections. Objectives. The collections of three libraries were analyzed for evidence of power law distributions with regard to the number of copies per title. Published version

To examine the association between specialist consultation and risk of 30-day ED revisit in emergency department (ED) patients with recent-onset uncomplicated atrial fibrillation or flutter (AF/AFL).As a secondary analysis of a previously published trial, clinical experts identified predictors of consultation including age and sex, ED sinus conversion, thromboembolic risk, heart rate, rate control medication use, coronary artery disease and anti-platelet use, and chronic obstructive pulmonary disease. These were included in a propensity-matched hierarchical Bayesian model accounting for hospital site as a random effect, with 30-day ED revisit as the primary outcome. We also measured ED length of stay for consulted and non-consulted patients.We analyzed data from 11 sites for 829 ED patients with AF/AFL, of whom 364 (44%) had specialist consultation. A total of 128 patients (15.4%) had an ED revisit, 78 (16.8%) from the no consult group and 50 (13.7%) from the consult group. Consultation rates ranged from 8.8 to 71% between sites. Median length of stay was 591 min (interquartile range [IQR] 359-1024) for consulted patients and 300 min (IQR 212-409) for patients without consultation. After propensity-matching, consulted patients had a 0.6% (IQR - 4 to 3%) lower risk of 30-day revisits than non-consulted patients (probability of lower risk 55%).In ED patients with uncomplicated AF/AFL, there was substantial between-site variation in specialist consultations; such consultation was unlikely to influence revisits within 30 days while ED length of stay was nearly double. ED specialist consultations may not be necessary for uncomplicated patients.RéSUMé: OBJECTIFS: Examiner l'association entre la consultation d'un spécialiste et le risque d'une nouvelle visite aux urgences à 30 jours chez les patients des urgences souffrant de fibrillation auriculaire ou de flutter non compliqué d'apparition récente (FA/AFL). MéTHODES: Dans le cadre d'une analyse secondaire d'un essai précédemment publié, des experts cliniques ont identifié les facteurs prédictifs de la consultation, notamment l'âge et le sexe, la conversion sinusale des urgences, le risque thromboembolique, la fréquence cardiaque, l'utilisation de médicaments pour contrôler la fréquence cardiaque, la maladie coronarienne et l'utilisation d'antiplaquettaires, et la maladie pulmonaire obstructive chronique. Ceux-ci ont été inclus dans un modèle bayésien hiérarchique apparié en fonction de la propension, qui tient compte du site de l'hôpital comme effet aléatoire, le critère principal étant le retour aux urgences à 30 jours. Nous avons également mesuré la durée de séjour aux urgences des patients consultés et non consultés. RéSULTATS: Nous avons analysé les données de 11 sites pour 829 patients du service d'urgence atteints de FA/AFL, dont 364 (44 %) avaient consulté un spécialiste. Un total de 128 patients (15,4 %) ont eu une nouvelle visite à l'urgence, 78 (16,8 %) du groupe sans consultation et 50 (13,7 %) du groupe de consultation. Les taux de consultation variaient de 8,8 % à 71 % selon les sites. La durée médiane du séjour était de 591 minutes (intervalle interquartile [IQR] 359-1024) pour les patients consultés et de 300 min (IQR 212-409) pour les patients sans consultation. Après appariement par propension, les patients consultés avaient un risque inférieur de 0,6 % (IQR -4 % à 3 %) de revisites à 30 jours par rapport aux patients non consultés (probabilité de risque inférieur de 55 %). CONCLUSIONS: Chez les patients des urgences atteints de FA/AFL non compliquée, il y avait une variation substantielle entre les sites dans les consultations de spécialistes ; il était peu probable qu'une telle consultation influence les visites dans les 30 jours alors que la durée du séjour aux urgences était presque le double. Les consultations de spécialistes des urgences peuvent ne pas être nécessaires pour les patients sans complication.

ObjectiveClinical trials for patients with shock-refractory out-of-hospital cardiac arrest (OHCA), including the Amiodarone, Lidocaine or Placebo (ALPS) trial, have been unable to demonstrate definitive benefit after treatment with antiarrhythmic drugs. A Bayesian approach, combining the available evidence, may yield additional insights.MethodsWe conducted a reanalysis of the ALPS trial comparing treatment with amiodarone or lidocaine with placebo in patients with OHCA following shock-refractory ventricular fibrillation or ventricular tachycardia (VF/VT). We used Bayesian regression to assess the probability of improved survival or improved neurological outcome on the 7-point modified Rankin Scale. We derived weak, moderate and strong priors from a previous clinical trial.ResultsThe original ALPS trial randomised 3026 adult patients with OHCA to amiodarone (n=974, survival to hospital discharge 24.4%), lidocaine, (n=993, survival 23.7%) or placebo (n=1059, survival 21.0%). In our reanalysis the probability of improved survival from amiodarone ranged from 83% (strong prior) to 95% (weak prior) compared with placebo and from 78% (strong) to 90% (weak) for lidocaine—an estimated improvement in survival of 2.9% (IQR 1.4%–3.8%) for amiodarone and 1.7% (IQR 0.84%–3.2%) for lidocaine over placebo (moderate prior). The probability of improved neurological outcome from amiodarone ranged from 96% (weak) to 99% (strong) compared with placebo and from 88% (weak) to 96% (strong) for lidocaine.ConclusionsIn a Bayesian reanalysis of patients with shock-resistant VF/VT OHCA, treatment with amiodarone had high probabilities of improved survival and neurological outcome, while treatment with lidocaine had a more modest benefit.

Soil and water contaminations are caused by rare earth elements (REEs) due to mining and industrial activities, that threaten the ecosystem and human health. Therefore, phytoremediation methods need to be developed to overcome this problem. To date, little research has been conducted concerning the phytoremediation potential of Salix for REEs. In this study, two Salix species (Salix myrsinifolia and Salix schwerinii) and two Salix cultivars (Klara and Karin) were hydroponically exposed to different concentrations of six-REE for 4 weeks. The treatments were: T1 (Control: tap water), T2 (La: 50 mg/L) and T3 (La 11.50 + Y 11 + Nd 10.50 + Dy 10 + Ce 12 and Tb 11.50 in mg L

During the bioethanol production process, vast amounts of residues are generated as process waste. To extract more value from lignocellulosic biomass and improve process economics, these residues should be used as feedstock in additional processes for the production of energy or fuels. In this paper, barley straw was used for bioethanol production and the residues were valorized using anaerobic digestion (AD) or used for the production of heat and power by combustion. A traditional three-step bioethanol production process was used, and the biomass residues obtained from different stages of the process were analyzed. Finally, mass and energy balances were calculated to quantify material flow and assess the different technological routes for biomass utilization. Up to 90 kg of ethanol could be produced from 1 t of biomass and additional biogas and energy generated from processing residues can increase the energy yield to over 220%. The results show that in terms of energy output, combustion was the preferable route for processing biomass residues. However, the production of biogas is also an attractive solution to increase revenue in the bioethanol production process.

Hydrothermal carbonization (HTC) is a thermochemical process, wherein biomass is subjected to high-pressure, high-temperature subcritical water to improve the combustion characteristics of biomass ...

The time-dependent layer-formation process of the agglomerates for three common agricultural residues in Australia with different ash-forming elements, together with quartz sand as the bed material, were investigated in a lab-scale, fixed-bed reactor under combustion (5% v/v O2) and steam-gasification (50% v/v steam) atmospheres at 900 °C. The impact of the atmosphere on the ash–bed material interaction was studied from the elemental composition and the morphology of the agglomerates, which were characterized with scanning electron microscopy in combination with energy-dispersive X-ray spectroscopy. The ash–bed material interaction mechanisms for the three feedstock were identified as part of the alkali metals react to form ash particles, which, for wheat straw and cotton stalks, consist of Na, Mg, Si, P, K, and Ca and, for grape marc, is composed mostly of KCaPO4; the remaining alkali metals react with either Si from the quartz sand (for grape marc and cotton stalk) or reactive Si from the fuel (for whea...

Hydrothermal carbonization (HTC) can potentially improve the fuel quality of low-value biomass resources that are otherwise unsuitable for use in industrial heat and power applications. The effect of HTC pretreatment on the combustion and gasification behavior of two agricultural residues (grape marc and sugar cane bagasse) and a freshwater species of macroalgae was investigated, with an emphasis on devolatilization behavior and char reactivity. HTC was carried out in a custom-built, laboratory-scale, batch reactor at three temperatures, 180, 220, and 260 °C, with a slurry density of 15% w/w dry biomass in water. The volatile release behavior of the collected products (hydrochars) and untreated biomass feedstocks were characterized by dynamic thermogravimetric analysis. Char reactivity was characterized by isothermal gasification of samples of the hydrochars and untreated biomass in a thermobalance in carbon dioxide, following fast pyrolysis of the samples in a separate fixed-bed batch reactor. Hydrochars...

Development of thermal processes for selective recovery of Zn and other valuable elements from municipal solid waste incineration (MSWI) fly ash requires comprehensive knowledge of the impact of gas atmosphere on the volatile behaviour of the element constituents of the ash at different reaction temperatures. This study assesses the partitioning of 18 elements (Al, As, Bi, C, Ca, Cd, Cl, Cu, K, Mg, Na, P, Pb, S, Sb, Sn, Ti, and Zn) between condensed and gaseous phases during thermal treatment of MSWI fly ash in both oxidising gas and reducing gas atmospheres, at different temperatures spanning the range 200–1050 °C. The operating atmosphere had major impacts on the partitioning of the following elements: As, Bi, C, Cd, Cu, Na, Pb, S, Sb, Sn, and Zn. The partitioning of these elements cannot be accurately predicted over the full range of investigated operating conditions with global thermodynamic equilibrium calculations alone, i.e. without also considering chemical kinetics and mass transfer. In oxidising conditions, the following elements were predominately retained in condensed phases, even at high temperatures: As, Bi, Sb, Sn, and Zn. All these elements, except As, were largely released to the gas phase (>70%) at high temperatures in reducing conditions. The impact of gas atmosphere on the volatility of Cd and Pb was greatest at low reaction temperatures (below ~750 °C). Results for volatile matrix elements, specifically C, Cl, K, Na, and S, are interpreted in terms of the mechanisms governing the release of these elements to the gas phase.

This study assesses the potential of thermal processing for detoxification of wood-combustion ashes that contain high levels of Cr and Cd. Thermal treatment (1000 °C) of bottom ash and fly ash in an oxidising gas (air) atmosphere resulted in: low volatilisation of Cd and most other heavy metals, oxidation of Cr in the ashes to Cr (VI), and, in the case of the fly ash, significantly increased leaching of Cr and Mo. Thermal treatment in a nitrogen atmosphere resulted in local reducing conditions due to oxidation of ash-derived carbon to CO (g). Thermal treatments in this atmosphere and in a reducing atmosphere consisting of 10 % H2 and the balance N2 detoxified the ashes in at least two ways: (i) by substantially removing Cd, Pb, Bi, Tl, and, in the case of the fly ash, Zn from the ashes by volatilisation; and (ii) by thermal reduction of Cr (VI) in the ashes. There was at least a 100-fold reduction in the leaching of total Cr from both the bottom ash and the fly ash following the thermal treatments in reducing conditions. Chromium only leached from the detoxified bottom ash to a significant extent in acidic conditions (pH

This study assesses the volatility of 15 elements (As, Bi, C, Cd, Cl, Cu, K, Mn, Na, P, Pb, S, Sb, Sn, and Zn) during thermal processing of fly ashes obtained from four waste-to-energy plants and one wood-combustion plant. Differences in volatility in oxidising and reducing atmospheres (air and 10% H2/90% N2) were assessed at two temperatures, 700 and 1000 °C. P and Mn were predominately retained in all ashes regardless of the operating atmosphere and temperature. Other elements showed significant variation in volatility depending on the type of fly ash, atmosphere, and temperature. Heat-treatment of the wood-combustion fly ash in the air atmosphere resulted in low release of K, Na, and all investigated heavy metals and metalloids. Several valuable elements, including Zn, Sb, Sn, and Bi, were significantly more volatile in the reducing atmosphere than in the oxidising atmosphere, particularly at 1000 °C. Other elements were either less volatile, equally volatile, or only marginally more volatile when the ashes were heated at 1000 °C in the reducing atmosphere. These elements include C, Cl, Cu, and, in the case of fly ashes derived from municipal solid waste, Cd and Pb. A two-step process, in which municipal solid waste incineration fly ash is first heated in an oxidising atmosphere and then in a reducing atmosphere, is proposed for production of a chloride-free zinc concentrate. Evaluation of the two-step process at 880 °C shows good potential for selective volatilisation of Zn with other valuable elements, including Sn, Sb, and Bi.

Custom copper smelters impose substantial financial penalties for the presence of deleterious impurity elements in copper concentrates and can outright reject concentrates which contain impurity elements in concentrations that exceed specified values. Hence, there is strong motivation to remove penalised impurity elements from copper concentrates at the mine site before shipping to custom smelters. A number of leach systems have been developed for the selective extraction of penalty elements from copper concentrates, including: alkaline sulphide leaching (ASL); hypochlorite leaching; dilute sulphuric acid leaching with aluminium sulphate; and combined pressure oxidation (POX) leaching with copper precipitation leaching. This paper reviews these four systems with emphasis on the leaching behaviour of penalty elements. ASL has previously been employed in industry for the selective extraction of As and Sb from tetrahedrite-rich copper concentrates. Sodium sulphide solution leaches As, Sb, and Hg from a large range of minerals, however, does not leach arsenopyrite, a mineral which often contains a significant portion of the total As in copper concentrates. Hypochlorite leaching extracts As associated with enargite minerals. This leach system benefits from superior rates of As extraction when compared with ASL, and for this reason, has gained recent interest within the research community. Two major issues have been identified with hypochlorite leaching of copper concentrates. These are poor reagent selectivity towards As-bearing minerals and high levels of hypochlorite consumption. Unless these two issues are resolved it is unlikely that hypochlorite leaching will be employed in commercial processes. Dilute sulphuric acid leaching with aluminium sulphate is used to extract F associated with fluorite. This leach system also extracts F associated with apatite and chlorite. Laboratory-scale experiments and extensive operating experience have indicated that fluorite can be substantially leached from copper concentrates without addition of aluminium sulphate provided that the concentration of sulphuric acid in the leach solution is sufficiently high (at least 40 g L−1). POX/copper precipitation leach systems have potential to extract a large number of penalty elements from copper sulphide concentrates while simultaneously upgrading the concentration of copper in the concentrate. Two patented POX/copper precipitation leach processes have been specifically developed for the deportment of penalty elements. These two processes are reviewed in detail.

Municipal solid waste incineration fly ashes can contain high concentrations of Zn and other valuable elements including Cu, Pb, Sn, and Sb. These elements can potentially be separated from fly ashes by selectively volatilising and condensing them in thermal processes. This study presents a thermal process for production of zinc concentrates from fly ashes and assesses the impact of the reducing gas atmosphere used in the process on the volatility of Zn, Pb, and Cu. Concentrates were produced by heating samples of municipal solid waste incineration fly ash in a reducing atmosphere, consisting of 10% H2 and 90% N2, and selectively condensing elements which volatilised from the ash at 900 and 1100 °C. Thermodynamic equilibrium calculations were used to predict the volatile behaviour of Zn, Pb, and Cu in the reducing atmosphere and in an oxidising atmosphere (air). The extent of volatilisation of these elements was also determined experimentally for both the reducing atmosphere and the oxidising atmosphere by means of mass balances based on elemental analyses of untreated and heat-treated ashes. The concentrate produced at 900 °C contained high concentrations of Zn (55.9 ± 12.5% w/w) and Pb (4.7 ± 1.1% w/w). These metals and other higher value elements, specifically, Sn, Sb, and Bi, were greatly enriched in the concentrates when compared with the untreated fly ash, showing a high potential for the developed process to separate multiple valuable elements from ashes. However, several deleterious impurities, particularly K, Na, and Cd, also reported to the concentrates in significant concentrations. Further refinements to the process are needed to separate these elements from Zn. The reducing gas atmosphere substantially increased the volatility of Zn, but suppressed the volatility of Cu and, to a lesser extent, the volatility of Pb. The equilibrium calculations overestimated the release of Cu in oxidising conditions and the release of Zn and Pb in both oxidising and reducing conditions.

The interactions between ash and quartz sand as the bed material were studied for two species of macroalgae, Oedogonium intermedium (a freshwater species) and Derbesia tenuissima (a marine species). The interaction tests were performed in a lab-scale, fixed-bed reactor under a steam gasification (50% v/v steam) or a combustion (5% v/v O2) atmosphere at 900 °C for different reaction times (10 min to 6 h). For both macroalgae, some of the Na and K are found to interact with other elements, such as Mg, Si, P, Ca and Fe to form ash particles. For ODN, these low melting-point phosphorus-rich ash particles are present in sufficient quantities to adhere to the quartz sand and form agglomerates via a melting-induced mechanism. In addition, some of the Na and K react with Si from the quartz sand to form a coating layer, which promotes a coating-induced mechanism. Both mechanisms contribute to a similar extent for ODN; while the coating-induced mechanism dominates for Deb, which includes the diffusion of some Ca into the coating layer. For Deb, the steam gasification atmosphere significantly affects the size of the agglomerates, the mass fractions of K and Na retained in the agglomerates and the formation of various types of silicates in the agglomerates, when compared with those under the combustion atmosphere. However, the influence of the steam gasification atmosphere on both the morphology and the elemental composition of the ODN agglomerates is less obvious. For Deb, a high content of S is detected for the individual separate ash particles within the agglomerates during combustion, whereas negligible S is found during steam gasification.

The work presented here assesses the potential for the mobilisation of 11 trace elements (As, Be, Co, Cu, Mn, Ni, Pb, Sb, Se, V, Zn) during the thermal conversion of micro-and macroalgae that were cultivated in ash dam water. The volatility of the trace elements was quantified by mass balances based on elemental analyses of char and ash residues. The residues were prepared in a laboratory-scale fixed-bed reactor at a range of different temperatures (500-1100 degrees C) and gas atmospheres (N-2, 2% O-2 and CO2) to simulate pyrolysis, combustion and gasification processes. The results showed high volatilities for Se (similar to 79-97%) and As (similar to 51-79%) below 500 degrees C. Zn, Pb and Sb were mainly volatilised above 700 degrees C. The different gas atmospheres had little influence on the volatility of these elements, which increased sharply to more than 90% with increasing temperature from 700 to 1100 degrees C. Volatilities for V, Mn, Cu, Co, Ni and Be were relatively minor over the full range of investigated operating conditions. Samples of each alga and their thermal conversion residues were subject to batch leaching in water. All of the tested trace elements, except for Pb and Be, were partially leached from the algae. Vanadium was up to 4-5 times more leachable in the combustion residues than in the algae. The other trace elements were generally less leachable following thermal conversion. The trace elements were more stable in residues prepared under pyrolysis and gasification conditions than in residues prepared under combustion conditions at the same temperature.

The release of volatile inorganic elements during thermal conversion of algal biomass may cause operational problems in industrial reactors such as fouling, deposition, corrosion, and bed agglomeration. The release of Cl, S, P, K, and Na during the thermal conversion of algal biomass has been experimentally investigated in this paper. A freshwater macroalga (Oedogonium sp.), a freshwater polyculture of microalgae, and a marine microalga (Tetraselmis sp.) were used as feedstocks to assess the influence of different species and culturing environments on the release of the inorganic elements. Char and ash samples were prepared in a laboratory-scale fixed-bed reactor under isothermal conditions ranging from 500 to 1100 °C, under pyrolysis, combustion, and gasification atmospheres. The release of the inorganic elements was quantified by mass balances based on elemental analyses of the char and ash residues. Differences in the release of Cl, S, K, and Na were significant between the marine alga and the freshwat...

The work presented here provides greater insight into the occurrence of the main inorganic elements in algae and how this varies for different species of algae and production methods. It also provides valuable insights into the behavior of algal ashes during combustion, particularly in regard to their interaction with quartz bed material, which is of direct relevance to agglomeration in fluidized bed reactors. A diverse range of algal species was selected for this work using a species of marine microalgae (Tetraselmis sp.) and marine macroalgae (Derbesia tenuissima) and a species of freshwater macroalgae (Oedogonium sp.). Two samples of Oedogonium were tested. One sample was cultivated using a standard nutrient addition regime, and the other was starved of essential nutrients at the completion of the culture cycle. Samples of algae were subject to chemical fractionation and the mode of occurrence of the main inorganic elements was inferred from their leaching behavior. Both the relative proportions of the...

Recent focus on algae biomass as an alternative energy source can be attributed to building pressure for conservation of dwindling fossil fuels and reduced greenhouse gas emissions. Both micro- and macroalgae have many advantages over terrestrial plants, including typically faster growth rates and, therefore, higher rates of carbon fixation. This paper reports the combustion characteristics of a species of microalgae and two species of macroalgae under conditions that are relevant for the large-scale use of biomass for heat and other products. The tested species were Tetraselmis sp. (marine microalgae), Derbersia tenusissima (marine macroalgae), and Oedogonium sp. (freshwater macroalgae). Two variants of Oedogonium were tested. One variant was cultivated using standard nutrient additions, and the other variant was starved of essential nutrients. Carbon conversion to CO and CO2 and the release of N as NO were determined for the algae by oxidizing fixed-bed samples of each alga in air at 800 and 1000 °C. Th...

The distributions of 210Pb and 210Po, short half-life products of 238U decay, in geological and related anthropogenic materials are reviewed, with emphasis on their geochemical behaviours and likely mineral hosts. Concentrations of natural 210Pb and 210Po in igneous and related hydrothermal environments are governed by release from crustal reservoirs. 210Po may undergo volatilisation, inducing disequilibrium in magmatic systems. In sedimentary environments (marine, lacustrine, deltaic and fluvial), as in soils, concentrations of 210Pb and 210Po are commonly derived from a combination of natural and anthropogenic sources. Enhanced concentrations of both radionuclides are reported in media from a variety of industrial operations, including uranium mill tailings, waste from phosphoric acid production, oil and gas exploitation and energy production from coals, as well as in residues from the mining and smelting of uranium-bearing copper ores. Although the mineral hosts of the two radionuclides in most solid media are readily defined as those containing parent 238U and 226Ra, their distributions in some hydrothermal U-bearing ores and the products of processing those ores are much less well constrained. Much of the present understanding of these radionuclides is based on indirect data rather than direct observation and potential hosts are likely to be diverse, with deportments depending on the local geochemical environment. Some predictions can nevertheless be made based on the geochemical properties of 210Pb and 210Po and those of the intermediate products of 238U decay, including isotopes of Ra and Rn. Alongside all U-bearing minerals, the potential hosts of 210Pb and 210Po may include Pb-bearing chalcogenides such as galena, as well as a range of sulphates, carbonates, and Fe-oxides. 210Pb and 210Po are also likely to occur as nanoparticles adsorbed onto the surface of other minerals, such as clays, Fe-(hydr)oxides and possibly also carbonates. In rocks, unsupported 210Pb- and/or 210Po-bearing nanoparticles may also be present within micro-fractures in minerals and at the interfaces of mineral grains. Despite forming under very limited and special conditions, the local-scale isotopic disequilibrium they infer is highly relevant for understanding their distributions in mineralized rocks and processing products.