Explore the vast range of titles available.

The distribution of rare earth elements (REEs) between amphibole and silicate melt is important for understanding a wide variety of igneous and metamorphic processes in the lithosphere. In this study, we used published experimental REE and Y partitioning data between amphibole and silicate melt, the lattice strain model, and nonlinear least-squares regression method to parameterize key partitioning parameters in the lattice strain model (D0, r0, and E) as a function of pressure, temperature, and both amphibole and melt compositions. Two models, which give nearly identical results, are obtained in this study. In the first model, D0 depends on temperature and amphibole composition: it positively correlates with Ti content and negative correlates with temperature and Mg, Na, and K contents in the amphibole. In the second model, D0 depends solely on the melt composition: it positively correlates with Si content and negatively correlates with Ti and Ca contents in the melt. In both the mineral and melt composition models, r0 negatively correlates with the ferromagnesian content in the M4 site of the amphibole, and E is a constant. The very similar coefficients in the equations for r0 and best-fit values for E in the two models allow us to connect the two models through amphibole-melt phase equilibria. An application of our model to amphiboles in mantle xenoliths shows that observed major element compositional variations in amphibole alone can give rise to order of magnitude variations in amphibole-melt REE partition coefficients. Together with experimental data simulating fractional crystallization of arc magmas, out models suggest that: (1) REE partition coefficients between amphibole and melt can vary by an order of magnitude during arc magma crystallization due to variation in the temperature and composition of the amphibole and melt, and that (2) amphibole fractional crystallization plays a key role in depleting the middle REEs relative to heavy REEs and light REEs in arc magmas.

Polycyclic aromatic hydrocarbon (PAH) desorption partition coefficients between black carbon and water (KBC) were determined using 114 historically contaminated and background sediments from eight different rural and urban waterways. Black carbon was measured after oxidation at 375°C for 24 h. Organic carbon–water partition coefficients (KOC) required for the calculation of KBC values were determined for two‐ to six‐ring parent and C1‐ to C4‐alkyl PAHs based on the lower range of measured KOC values from the same sediments and comparisons to literature KOC values. Approximately 2,050 log KBC values were determined on sediments having a range of total organic carbon from 0.3 to 42% by weight, black carbon from 0.1 to 40% by weight, and total PAH concentrations (U.S. Environmental Protection Agency 16 parent PAHs) from 0.2 to 8,600 μg/g. Contrary to expectations, PAH partitioning was not better explained using the combined KOC and KBC models rather than the simple KOC model (i.e., KBC values for each individual PAH ranged nearly three orders of magnitude). No effect of PAH concentration on measured KBC values was apparent. Values of KBC also showed no trends with total organic carbon, black carbon, or the presence or absence of a nonaqueous phase liquid. Multiple linear regression analysis with KOC and KBC as fitted values also failed to explain the variance of the experimental data (r2 values typically less than 0.20, and standard errors greater than two orders of magnitude). These results demonstrate that models of PAH partitioning that account for different carbon types, although useful for understanding partitioning mechanisms, cannot yet be used to accurately predict PAH partitioning from historically contaminated sediments.

Polyethylene (PE) and other polymers are widely and successfully used as passive samplers for organic pollutants in the environment. This study provides high-resolution experimental data from batch shaking tests on the uptake, reversibility, and linear equilibrium partitioning of polycyclic aromatic hydrocarbons (PAHs) using two different PE sheets of 30 µm and 80 µm thickness. Kinetics for phenanthrene are well described by a mechanistic first-order model with mass transfer limited by an aqueous boundary layer (with a mean thickness of 170 µm). Equilibration in laboratory batch systems during uptake and desorption is very rapid with characteristic times of 1–2 h but this depends on the boundary condition, e.g., the ratio of PE mass to water volume. Therefore, equilibration of PE in other setups, e.g., in soil slurries or sediment suspensions, may take orders of magnitude longer because the boundary condition for PE changes from finite to infinite bath conditions (soil or sediment particles may keep the concentration in water almost constant). Solid precipitates for high molecular weight PAHs explain partition coefficients below expected values because of kinetic limitations in such a system. Nevertheless, passive sampling can be employed safely if such limitations are considered; furthermore, partition coefficients can be estimated accurately by empirical relationships (e.g., within 0.1 log unit) based on molecular weight, octanol/water partition coefficients, or subcooled liquid solubilities.

Hydrogen distribution between nominally anhydrous minerals (NAMs) of a garnet-lherzolite under subsolidus conditions has been investigated. Separated NAMs from a garnet-peridotite from Patagonia (Chile) are annealed together (olivine, orthopyroxene, clinopyroxene, and garnet) using a piston-cylinder at 3 GPa and 1100 °C using talc-pyrex cell assembly for 10, 25, and 100 h. The talc-pyrex assembly provides enough hydrogen in the system to re-equilibrate the hydrogen concentrations at high pressure. The three coexisting nominally anhydrous minerals (NAMs, i.e., olivine, orthopyroxene, and clinopyroxene) were successfully analyzed using FTIR. The resulting hydrogen concentrations exceed significantly the initial hydrogen concentration by a factor of 13 for olivine and a factor of 3 for both pyroxenes. Once mineral-specific infrared calibrations are applied, the average concentrations in NAMs are 115 ± 12 ppm wt H2O for olivine, 635 ± 75 ppm wt H2O for orthopyroxene, and 1214 ± 137 ppm wt H2O for clinopyroxene, garnet grains are dry. Since local equilibrium seems achieved over time (for 100 h), the calculated concentration ratios are interpreted as mineral-to-mineral hydrogen partition coefficients (i.e., Nernst's law) for a garnet-peridotite assemblage. It yields, based on mineral-specific infrared calibrations, DOpx/Ol = 5 ± 1, DCpx/Ol = 10 ± 2, and DCpx/Opx = 1.9 ± 0.4. While DCpx/Opx is in agreement (within error) with previous results from experimental studies and concentration ratios observed in mantle-derived peridotites, the DPx/Ol from this study are significantly lower than the values reported from mantle-derived xenoliths and also at odd with several previous experimental studies where melt and/or hydrous minerals co-exists with NAMs. The results confirm the sensitivity of hydrogen incorporation in olivine regarding the amount of water-derived species (H) in the system and/or the amount of water in the coexisting silicate melt. The results are in agreement with an important but incomplete dehydration of mantle-derived olivine occurring at depth, during transport by the host magma or during slow lava flow cooling at the surface. The rapid concentration modification in mantle pyroxenes also points out that pyroxenes might not be a hydrogen recorder as reliable as previously thought.

Reverse osmosis (RO) and nanofiltration (NF) are ubiquitous technologies in modern water treatment, finding applications across various sectors. However, the availability of high-quality water suitable for RO/NF feed is diminishing due to droughts caused by global warming, increasing demand, and water pollution. As concerns grow over the depletion of precious freshwater resources, a global movement is gaining momentum to utilize previously overlooked or challenging water sources, collectively known as “marginal water”. Fouling is a serious concern when treating marginal water. In RO/NF, biofouling, organic and colloidal fouling, and scaling are particularly problematic. Of these, organic fouling, along with biofouling, has been considered difficult to manage. The major organic foulants studied are natural organic matter (NOM) for surface water and groundwater and effluent organic matter (EfOM) for municipal wastewater reuse. Polymeric substances such as sodium alginate, humic acid, and proteins have been used as model substances of EfOM. Fouling by low molecular weight organic compounds (LMWOCs) such as surfactants, phenolics, and plasticizers is known, but there have been few comprehensive reports. This review aims to shed light on fouling behavior by LMWOCs and its mechanism. LMWOC foulants reported so far are summarized, and the role of LMWOCs is also outlined for other polymeric membranes, e.g., UF, gas separation membranes, etc. Regarding the mechanism of fouling, it is explained that the fouling is caused by the strong interaction between LMWOC and the membrane, which causes the water permeation to be hindered by LMWOCs adsorbed on the membrane surface (surface fouling) and sorbed inside the membrane pores (internal fouling). Adsorption amounts and flow loss caused by the LMWOC fouling were well correlated with the octanol-water partition coefficient (log P). In part 2, countermeasures to solve this problem and applications using the LMWOCs will be outlined.

Estrogens have been widely detected in water and might pose a potential threat to the aquatic ecosystem. However, little information is available about the occurrence, multi-phase fate and potential risks of estrogens in Hanjiang River (HR). In this work, the concentration, multi-phase distribution and risk assessment of eight estrogens were studied by investigating surface water and sediment samples from HR during two seasons. These samples were analyzed using the solid-phase extraction (SPE) and liquid chromatography-mass spectrometry (LC-MS). The concentrations of eight estrogens were 4.5–111 ng/l in surface water and 1.7–113 ng/g dry weight in sediments. 4-nonylphenol (NP) was the predominant estrogen in both water and sediments. The estrogens showed significantly spatial variability, with the highest average concentration in the lower section of HR (p < 0.01, F > 12.21). Meanwhile, NP, 17α-estradiol (αE2), Bisphenol A (BPA) and 4-tert-octyphenol (OP) in surface water exhibited higher concentrations in summer than in winter (p < 0.05, F > 4.62). The sediment-water partition coefficients of estrogens suggested that these compounds partitioned more to particulate phase. Risk assessment indicated that estriol (E3) was the main contributor to the total estradiol equivalent concentration. Moreover, estrogen mixtures could pose high ecological risks to aquatic organisms in surface water. Overall, estrogens are ubiquitous in HR, and their potential ecological risks should not be neglected.

Fourteen pesticides were screened and determined through quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction process combined with GC-MS/MS in arid agriculture soil. The aims of the current investigation were to account the occurrence of organochlorine (OCP) and organophosphates (OPP) pesticide residues as well as other groups of pyrethroids (PYRs), carbamates, and biopesticides using a combined of QuEChERS and GC-MS/MS techniques in agriculture soils at Al-Kharj region, Saudi Arabia, and to investigate correlation between pesticide losses in soils and some physicochemical characteristics of pesticides including an octanol-water coefficient partition (Kow) and the vapor pressure (Vp). Prediction of pesticide fate by considering both pesticide and soil physio-chemical properties will facilitate the management of pesticide application and minimize the hazards of environmental pollution. The fate of pesticide residue in soils is generally controlled by soil/air exchange, water interaction, and biodegradation. The results indicated that 14 pesticide residues were measured in collected samples of various soils, spinosad, chlorpyrifos methyl, dimethoate, chlorpyrifos, lindane (γ-HCH), permethrin, and methomyl which were the most abundant sources of contamination in the studied region. p,p-DDT, o,p-DDT, bifenthion, β-cyfluthrin, and methidathion were less commonly detected. Single parameter least squares regression equations (sp-LSRE) for Vp and Kow against the loss of each pesticide residue showed a significant change in concentration levels (p < 0.05) between the two seasons. The results showed that vapor pressure and octanol-water partition coefficient data are not enough to model pesticide residue losses in arid low organic carbon soil. More soil-related data is needed to describe the dissipation mechanisms of these pesticide residues in the region.

Chromite from Los Congos and Los Guanacos in the Eastern Pampean Ranges of Cordoba (Argentinian Central Andes) shows homogenous and exsolution textures. The composition of the exsolved phases in chromite approaches the end-members of spinel (MgAl2O4; Spl) and magnetite (Fe2+Fe23+O4; Mag) that define the corners of the spinel prism at relatively constant Cr3+/R3+ ratio (where R3+ is Cr+Al+Fe3+). The exsolution of these phases from the original chromite is estimated to have accounted at ≥600 °C on the basis of the major element compositions of chromite with homogenous and exsolution textures that are in equilibrium with forsterite-rich olivine (Fo95). The relatively large size of the exsolved phases in chromite (up to ca. 200 µm) provided, for the first time, the ability to conduct in situ analysis with laser ablation-inductively coupled plasma-mass spectrometry for a suite of minor and trace elements to constrain their crystal-crystal partition coefficient between the spinel-rich and magnetite-rich phases (DiSpl/Mag). Minor and trace elements listed in increasing order of compatibility with the spinel-rich phase are Ti, Sc, Ni, V, Ge, Mn, Cu, Sn, Co, Ga, and Zn. DiSpl/Mag values span more than an order of magnitude, from DTiSpl/Mag = 0.30 ± 0.06 to DZnSpl/Mag = 5.48 ± 0.63. Our results are in remarkable agreement with data available for exsolutions of spinel-rich and magnetite-rich phases in other chromite from nature, despite their different Cr3+/R3+ ratio. The estimated crystal-crystal partitioning coefficients reflect the effect that crystal-chemistry of the exsolved phases from chromite imposes on all investigated elements, excepting Cu and Sc (and only slightly for Mn). The observed preferential partitioning of Ti and Sc into the magnetite-rich phase is consistent with high-temperature chromite/melt experiments and suggests a significant dependence on Fe3+ substitution in the spinel structure. A compositional effect of major elements on Ga, Co, and Zn is observed in the exsolved phases from chromite but not in the experiments; this might be due to crystal-chemistry differences along the MgFe-1-Al2Fe-23+ exchange vector, which is poorly covered experimentally. This inference is supported by the strong covariance of Ga, Co, and Zn observed only in chromite from layered intrusions where this exchange vector is important. A systematic increase of Zn and Co coupled with a net decrease in Ga during hydrous metamorphism of chromitite bodies cannot be explained exclusively by compositional changes of major elements in the chromite (which are enriched in the magnetite component). The most likely explanation is that the contents of minor and trace elements in chromite from metamorphosed chromitites are controlled by interactions with metamorphic fluids involved in the formation of chlorite.

Purpose Graphene oxide (GO) nanomaterial has found wide potential industrial applications, but its life cycle environmental impact is not fully understood mainly because of lack of characterization factors (CFs) for the life cycle impact assessment. In this paper, we report the derivation of CF for freshwater ecotoxicity of GO based on the USEtox method. Methods The CF is derived based on the toxic effect factor, fate factor, and exposure factor of GO in the aquatic environment. The toxic effect factor is extracted from mechanistic toxicity studies available in the literature. The fate factor is derived with the colloidal method, and the exposure factor is determined through Langmuir adsorption isotherm for interactions between GO and dissolve organic carbon. Additionally, both fate factor and exposure factor are re-calculated through the default mass-balanced model in USEtox. The apparent octanol-water partition coefficient ( K ow ) required in the mass balanced model is determined via experiment. Other parameters are calculated according to the apparent K ow. Results and discussion The study derives a CF of 777.5 potentially affected species (PAF) day m 3 kg −1 for GO with a fate factor of 27.2 days and an exposure factor of 0.93. Sensitivity analysis suggests that variability from the effect factor is the dominant source leading changes in CF. The uncertainty of CF value can vary between ∼1 and 10 3 PAF day m 3 kg −1 . Comparison between the colloidal and the mass-balanced models indicates that heteroaggregation may be underestimated by using the apparent partition coefficient, and thus, a much higher estimate of fate factor is obtained from the mass-balanced model. Additionally, empirical formulae in the USEtox to correlate other coefficients with K ow are not proper to calculate bioaccumulation and adsorption with dissolved organic carbon since a virtually a unit exposure factor is obtained. Conclusion The derived CFs can be readily incorporated into future toxicity assessment on GO. The fate factor is calculated in the colloidal model while adsorption of dissolved organic carbon onto GO surface should be derived from the Langmuir isotherm. Compared to the colloidal-based method, the conventional mass-balanced method may not be well applicable to GO due to the significant uncertainties in fate and exposure factors from applying the apparent partition coefficients. As three orders of magnitude variations in CF are caused by effect factor due to limited toxicity tests available for GO, more toxicological studies of GO on various species are needed in the future.

The soil–water distribution coefficient of ionizable chemicals (Kd) depends on the soil acidity, mainly because the pH governs speciation. Using pH‐specific Kd values normalized to organic carbon (KOC) from the literature, a method was developed to estimate the KOC of monovalent organic acids and bases. The regression considers pH‐dependent speciation and species‐specific partition coefficients, calculated from the dissociation constant (pKa) and the octanol–water partition coefficient of the neutral molecule (log Pn). Probably because of the lower pH near the organic colloid–water interface, the optimal pH to model dissociation was lower than the bulk soil pH. The knowledge of the soil pH allows calculation of the fractions of neutral and ionic molecules in the system, thus improving the existing regression for acids. The same approach was not successful with bases, for which the impact of pH on the total sorption is contrasting. In fact, the shortcomings of the model assumptions affect the predictive power for acids and for bases differently. We evaluated accuracy and limitations of the regressions for their use in the environmental fate assessment of ionizable chemicals.