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The purpose of our study was to evaluate the ability of ureteral stents with different diameters to drain pus that accumulates in an obstructed kidney using an in vitro model.We developed an in vitro model of an obstructed kidney filled with pus. The model included a silicon kidney unit based on computed tomography (CT) data, a 3D printed ureteral stone based on a real extracted ureteral stone, a latex ureter model, a bladder vessel, and a fluid with qualities resembling pus. Identical printed stones were inserted into four ureter models containing stents with varying diameters (4.8F, 6F, 7F, 8F), each of which was connected to the kidney unit and the bladder vessel. The kidney unit was filled with artificial pus to pressures of 30 cmHThe rate of pressure drop and the final pressure measured in the kidney were unaffected by the diameter of the stent. For all stent diameters, the pressure reached non-obstructed levels within 30 s, final pressure was reached within 90-120 s, and minimal amounts of pus remained in the kidney after 120 min.In vitro experiments demonstrate that all stent diameters drain pus-filled, obstructed kidneys with the same efficacy. The common perception that larger diameter tubes are more effective under such circumstances should be re-examined.

Rare earth elements (REEs) play a crucial role in manufacturing high-tech products and developing various technologies, including those related to the transition to clean energy. Consequently, there has been a significant increase in REE production, which has the potential to contribute to the contamination of groundwater systems that are highly susceptible to industrial pollution. Groundwater REE contamination, specifically in coastal aquifer systems, could affect large populations that rely on that water for drinking and domestic use. In this study, we conducted column transport experiments using five representative coastal aquifer materials to understand better the mechanisms that control REE mobility and retention in coastal aquifers. These experiments were conducted by adding humic acid (HA) to the REE solution under fresh and brackish water conditions. The REEs were shown to be most mobile in sand samples, followed by two types of low-calcareous sandstone and one type of high-calcareous sandstone, and least mobile in red loamy sand. The mobility of REEs, found in solution primarily as REE-HA complexes, was controlled mainly by the retention of HA, which increases with ionic strength. Furthermore, it was found that the presence of carbonate and clay minerals reduces REE mobility due to enhanced surface interactions. The enrichment of middle-REE (Nd-Gd) was observed in the sand samples, while heavy-REE (Tb-Lu) enrichment was observed in the calcareous sandstones and the red loamy sand. This change in REE pattern likely originates from the release of carbonate ions from the carbonate minerals that stabilize heavy-REEs compared to middle-REEs.

Background and Purpose: Drainage of obstructed kidney due to extrinsic ureteral obstruction (EUO), required to prevent renal damage, is often achieved using double-J ureteral stents. But these stents fail frequently, and there is considerable debate regarding what stent size, type and configuration offer the best option for sustained drainage. Here, we examine the impact of stent diameter and choice of single/tandem configuration, subject to EUO and various degrees of stent occlusion, on stent failure. Methods: Computational fluid dynamics (CFD) simulations and an in vitro ureter-stent experiment enabled quantification of flow behavior in stented ureters subject to EUO and stent occlusions. Various single and tandem stents under EUO were considered. In each simulation and experiment, changes in renal pressure were monitored for different degrees of stent lumen occlusion, and onset of stent failure as well as simulated distributions of fluid flow between stent and ureter lumina were determined. Results: For an encircling EUO that completely obstructs the ureter lumen, with or without partial stent occlusion, the choice of stent size/configuration has little effect on renal pressure. The pressure increases significantly for ~90% stent lumen occlusion, with failure at >95% occlusion, independent of stent diameter or a tandem configuration, and with little influence of occlusion length along the stent. Conclusions: Stent failure rate is independent of stent diameter or single/tandem configuration, for the same percentage of stent lumen occlusion, in this model. Stent failure incidence may decrease for larger diameter stents and tandem configurations, because of the larger luminal area.

Urolithiasis is a frequent disease with cited rates of recurrence after initial diagnosis that vary widely and range between 35% and 50%. We assessed the radiographic recurrence rate in patients with urinary stones and its risk factors. We retrospectively identified patients who were diagnosed with urinary stones on non-contrast computed tomography from 2010 to 2011, and underwent another imaging examination at least six months afterwards. We collected patient demographic, clinical, laboratory and radiologic data and compared patients with and without urinary stone recurrence. Ultimately, 237 patients were included in the study; the mean follow-up was 6.7 years; 88 patients (37.1%) had recurrence based on our recurrence criteria. On univariate analysis, the significant parameters for recurrence were baseline serum calcium and uric acid, stone location in the kidney, surgical intervention and stone burden volume. On multivariate analysis, surgical intervention (OR 3.07, p = 0.001), baseline calcium (OR 2.56, p = 0.011), baseline uric acid (OR 1.30, p = 0.021) and stone location in the kidney (OR 2.16, p = 0.012) were associated with higher risk of recurrence. These findings may guide personalized follow-up protocols for patients with urolithiasis based on their risk factors.

To quantify the occurrence of stent failure and the dynamic behavior of urine flow in ureter-stent systems, including the relative flow in the ureter and stent lumina, subject to various degrees of ureter and stent blockage. Numerical simulations based on computational fluid dynamics (CFD) were used to quantify urine flow behavior in stented ureters, in the presence of extrinsic ureteral obstruction (EUO) and stent occlusions. Two stented ureter configurations were considered, one with circumferential occlusion of the ureter and the second with pressure on one side of the ureter wall. The pressure within the renal unit for different degrees of ureter closure and stent lumen occlusion was determined systematically. Onset of stent failure and the distribution of urine flow between stent and ureter lumina were determined. In the case of EUO completely encircling the ureter, causing 100% obstruction of the ureter lumen, pressure in the renal unit is essentially unaffected until the stent lumen reaches ~ 90% occlusion, and fails only with > 95% occlusion. Occlusions of 50% in stent side holes in the vicinity of the EUO only alter local flow patterns but have no significant influence on renal unit pressure. For EUO deforming and compressing the ureter from one side, with ~ 50% reduction in ureter lumen, urine drainage proceeds with negligible increase in renal pressure even with 100% occlusion in the stent lumen. CFD simulations show that stent failure under EUO tends to occur suddenly, only when both ureter and stent lumina become almost fully blocked.

Plastic nanoparticles (PNPs) are now widely recognized as a significant, and ever increasing, hazard in aquatic and soil environments. These particles, defined here as plastics

Background and Purpose: Drainage of an obstructed kidney due to extrinsic ureteral obstruction (EUO) is imperative. Ureteral stents, commonly employed to facilitate drainage, often fail under EUO; ...

Tal Amitay-Rosen,1 Ishai Dror,2 Yaniv Shilo,3 Brian Berkowitz2 1Department of Physical Chemistry, Institute for Biological Research, Ness-Ziona, 7410001, Israel; 2Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot, 7610001, Israel; 3Department of Urology, Kaplan Medical Center, Affiliated with the Hebrew University of Jerusalem, Rehovot, 7661041, IsraelCorrespondence: Brian Berkowitz, Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot, 7610001, Israel, Tel +972-8-9342098, Fax +972-8-9344124, Email brian.berkowitz@weizmann.ac.ilIntroduction: Ureteral stents are effective in alleviating flow disruptions in the urinary tract, whether due to ureteral stones, strictures or extrinsic ureteral obstruction. However, significant stent encrustation on the external and/or internal stent lumen walls can occur, which may interfere with stent functioning and/or removal. Currently, there is only limited, generally qualitative, information on the distribution, mineral structure, and chemical content of these deposits, particularly in terms of stent lumen encrustation.Objective: To quantify, in an initial investigation, external and internal encrustation in representative, intact ureteral stents. The study investigates possible correlations between patterns of external and internal encrustation, determines mineral structure and chemical composition, and examines the potential for stent lumen obstruction even in the absence of external stent wall encrustation.Study Design: High-resolution, laboratory micro-computed tomography (micro-CT) was used to non-destructively image external and internal stent encrustation in four representative stents. X-ray diffractometry (XRD) and scanning electron microscopy–energy dispersive x-ray spectroscopy (SEM-EDS) enabled parallel analysis of mineral structure and chemical content of samples collected from external and internal encrusted material along the distal, proximal and mid-ureteral stent regions.Results: Extensive stent lumen encrustation can occur within any region of a stent, with only incidental or minor external encrustation, along the entire length of the stent. External and internal encrusted materials in a given stent are generally similar, consisting of a combination of amorphous (mostly organic) and crystalline mineral deposits.Conclusion: Micro-CT demonstrates that significant stent lumen encrustation can occur, which can lead to partial or full stent lumen occlusion, even when the exterior stent wall is essentially free of encrusted material.Keywords: micro-computed tomography, stent deposition, mineral composition, obstruction, stent lumen

There is growing concern that rare earth elements (REEs) will become emerging soil-water contaminants because of their increased use in new technologies and products, which may lead to unavoidable release to the environment. To better understand the environmental behavior of REEs, a comprehensive set of adsorption and column transport experiments was conducted in quartz sand media. The retention and mobility of three representative REEs (La, Gd, and Er) were studied in the presence and absence of humic acid (HA; 5, 20, and 50 mg L

To quantify the relative volumetric flows in stent and ureter lumina, as a function of stent size and configuration, in both unobstructed and externally obstructed stented ureters.Magnetic resonance imaging was used to measure flow in stented ureters using a phantom kidney model. Volumetric flow in the stent and ureter lumina were determined along the stented ureters, for each of four single stent sizes (4.8F, 6F, 7F, and 8F), and for tandem (6F and 7F) configurations. Measurements were made in the presence of a fully encircling extrinsic ureteral obstruction as well as in benchmark cases with no extrinsic ureteral obstruction.Under no obstruction, the relative contribution of urine flow in single stents is 1-10%, while the relative contributions to flow are ~6 and ~28% for tandem 6F and 7F, respectively. In the presence of an extrinsic ureteral obstruction and single stents, all urine passes within the stent lumen near the extrinsic ureteral obstruction. For tandem 6F and 7F stents under extrinsic ureteral obstruction, relative volumetric flows in the two stent lumina are ~73% and ~81%, respectively, with the remainder passing through the ureter lumen.Magnetic resonance imaging demonstrates that with no extrinsic ureteral obstruction, minimal urine flow occurs within a stent. Stent lumen flow is significant in the presence of extrinsic ureteral obstruction, in the vicinity of the extrinsic ureteral obstruction. For tandem stents subjected to extrinsic ureteral obstruction, urine flow also occurs in the ureter lumen between the stents, which can reduce the likelihood of kidney failure even in the case of both stent lumina being occluded.

Background and Purpose: Extrinsic ureteral obstruction is caused frequently by pelvic malignancies or metastatic lymphadenopathy, necessitating renal drainage with ureteral stents to prevent renal ...

The transport of three platinum-based anticancer drugs (cisplatin, oxaliplatin and carboplatin) in soil–water environments, with and without the presence of two different types of surface functionalized polystyrene nanoparticles (PS-NPs; “nanoplastics”), was investigated. Recently, there is an increasing concern regarding the presence of micro and nanoplastics in aquatic and terrestrial ecosystems. Moreover, recent reports suggest that micro and nanoplastics may act as vehicles that enhance the mobility of other contaminants. Our transport studies indicate that PS-NPs may interact with pharmaceutical compounds and alter their mobility in a natural soil–water environment. Carboplatin showed “tracer like” mobility in soil without the presence of PS-NPs. When aminated PS-NPs were added to aqueous solutions, mobility of carboplatin in soil was reduced. Pt-complexes originating from cisplatin alone showed an elution of 35% of the inlet concentration at initial stages of the experiment with a gradual decrease to 15–20% recovery compared to the inlet concentration, while the presence of carboxylated PS-NPs significantly increases the recovery of Pt-complexes originating from cisplatin to ∼56–60%. Oxaliplatin showed the lowest mobility (5–10% recovery only); aminated PS-NPs increased the recovery by more than 4-fold, to 35–36%. Carboplatin showed both up and down regulation (toxic) effects on soil bacterial taxa, while Pt-complexes originating from cisplatin showed mostly toxic effects on the microbial community; oxaliplatin was the least toxic. PS-NPs alone had little impact on soil microbes, but their presence was found to significantly increase the toxicity of Pt-based pharmaceuticals for soil microbial populations.

The understanding of engineered nanoparticle (ENP) fate and transport in soil-water environments is important for the evaluation of potential risks of ENPs to the ecosystem and human health. The effects of pyrite grains and three types of oxyanions-sulfate, phosphate, and arsenate-on the retention of citrate-coated gold nanoparticles (citrate-Au-NPs) were studied in partially saturated soil column experiments. The mobility of Au-NP was found to be in the order: Au-NP-sulfide (originating from pyrite)Au-NP-sulfatecitrate-Au-NPAu-NP-arsenateAu-NP-phosphate. Chemical retention mechanisms, including hydrogen bonding and calcium bridging, are proposed and discussed. The retention of Au-NPs in soil columns increases with the increased ability of transformed Au-NP surfaces to create strong hydrogen bonding through adsorbed oxyanions with soil surfaces. Oxyanions were also found to reduce aggregation and aggregate size of Au-NPs upon interaction with Ca

Rare earth elements (REEs) are an emerging pollutant whose increasing use in various technological applications causes increasing risk of environmental contamination. Electronic waste (E-waste) could be one major source of REE pollution, as E-waste typically contains elevated REE concentrations and is often handled in unsafe and environmentally hazardous ways. Here, a series of leaching assays revealed that

Extensive use of nanomaterials in agriculture will inevitably lead to their release to the environment in significant loads. Thus, understanding the fate of nanoparticles in the soil-plant environment, and potential presence and consequent implication of nanoparticles in food and feed products, is required. We study plant uptake of gold nanoparticles from soil, and their distribution, translocation and speciation (in terms of particle size change and release of ionic Au) in the different plant tissues of four important crops (potato, radish, carrot and lettuce). Our new analytical protocol and experiments show the feasibility of determining the presence, concentration and distribution of nanoparticles in different plant parts, which differ from plant to plant. Critically, we identify the evident capacity of plants to break down (or substantially change the properties of) nanoparticles in the rhizosphere prior to uptake, as well as the evident capacity of plants to reorganize ionic metals as nanoparticles in their tissues. This could lead to nanoparticle exposure through consumption of crops.

Groundwater contamination originating from anthropogenic industrial activities is a global concern, adversely impacting health of living organisms and affecting natural ecosystems. Monitoring contamination in a complex groundwater system is often limited by sparse data and poor hydrogeological delineation, so that numerous indicators (organic, inorganic, isotopic) are frequently used simultaneously to reduce uncertainty. We suggest that selected Technology-Critical Elements (TCEs), which are usually found in very low concentrations in the groundwater environment, might serve as contamination indicators that can be monitored through aquifer systems. Here, we demonstrate the use of selected TCEs (in particular, Y, Rh, Tl, Ga, and Ge) as indicators for monitoring anthropogenic groundwater contamination in two different groundwater systems, near the Dead Sea, Israel. Using these TCEs, we show that the sources of local groundwater contamination are phosphogypsum ponds located adjacent to fertilizer plants in two industrial areas. In addition, we monitored the spatial distribution of the contaminant plume to determine the extent of well and spring contamination in the region. Results show significant contamination of the groundwater beneath both fertilizer plants, leading to contamination of a series of wells and two natural springs. The water in these springs contains elevated concentrations of toxic metals; U and Tl levels, among others, are above the maximum concentration limits for drinking water.

Transport of indium and gallium is reported in laboratory column experiments using quartz sand as a model porous medium representative of a groundwater system. With increased use of indium and gallium in recent years, mainly in the semiconductor industry, concerns arise regarding their environmental effects. The transport and retention behavior of these two metals were quantified via batch and column experiments, and numerical modeling. The effect of natural organic matter on indium and gallium mobility was studied by addition of humic acid (HA). Measured breakthrough curves from column experiments demonstrated different binding capacities between indium and gallium, stronger for indium, with the presence of HA affecting retention dynamics. For indium, the binding capacity on quartz decreases significantly in the presence of HA, leading to enhanced mobility. In contrast, gallium exhibits slightly higher retention and lower mobility in the presence of HA. In all cases, the binding capacity of gallium to quartz is much weaker than that of indium. These results are consistent with the assumption that indium and gallium form different types of complexes with organic ligands, with gallium complexes appearing more stable than indium complexes. Quantitative modeling confirmed that metal retention is controlled by complex stability.

In parallel to technological advances and ever-increasing use of nanoparticles in industry, agriculture and consumer products, the potential ecotoxicity of nanoparticles and their potential accumulation in ecosystems is of increasing concern. Because scientific reports raise a concern regarding nanoparticle toxicity to plants, understanding of their bioaccumulation has become critical and demands more research. Here, the synthesis of isotopically-labeled nanoparticles of silver, copper and zinc oxide is reported; it is demonstrated that while maintaining the basic properties of the same unlabeled ("regular") nanoparticles, labeled nanoparticles enable more sensitive tracing of nanoparticles within plants that have background elemental levels. This technique is particularly useful for working with elements that are present in high abundance in natural environments. As a benchmark, labeled and unlabeled metal nanoparticles (Ag-NP, Cu-NP, ZnO-NP) were synthesized and compared, and then exposed in a series of growth experiments to Arabidopsis thaliana; the NPs were traced in different parts of the plant. All of the synthesized nanoparticles were characterized by TEM, EDS, DLS, ζ-potential and single particle ICP-MS, which provided essential information regarding size, composition, morphology and surface charge of nanoparticles, as well as their stability in suspensions. Tracing studies with A. thaliana showed uptake/retention of nanoparticles that is more significant in roots than in shoots. Single particle ICP-MS, and scanning electron micrographs and EDS of plant roots showed presence of Ag-NPs in particular, localized areas, whereas copper and zinc were found to be distributed over the root tissues, but not as nanoparticles. Thus, nanoparticles in any natural matrix can be replaced easily by their labeled counterparts to trace the accumulation or retention of NPs. Isotopically-labeled nanoparticles enable acquisition of specific results, even if there are some concentrations of the same elements that originate from other (natural or anthropogenic) sources.

The need for better understanding of the environmental fate and transport of engineered nanoparticles (ENPs) is now a scientific consensus. However, the partially saturated zone, a critical region that links the earth's surface to aquifers, has to date received only minor attention in the context of ENP mobility. We investigate the transport and fate of a representative ENP, silver nanoparticles (Ag-NPs), in partially saturated soil. Here we present a set of column experiments and modelling simulations to examine breakthrough curves (BTCs), retention profiles, and mass balances that characterize Ag-NP transport, and gain insights into retardation mechanisms. Unlike Ag-NP transport in sand columns, where the BTC pattern often resembles that of a conservative tracer, Ag-NP transport in soil columns shows moderate mobility and more complex BTC patterns; these results also emphasize the importance of employing realistic porous media in environmental studies. Overall, Ag-NP mobility decreases in the presence of Ca(NO3)2, and increases when the solution contains humic acid, at higher water saturation levels, or at higher input concentrations of Ag-NPs. In addition, a different pattern was observed for Ag-NP aggregates, indicating nanospecific behaviour. Modelling analysis of Ag-NP transport in partially saturated soil suggests that a two-site kinetic model with a time-dependent retention function quantifies the transport behaviour of Ag-NPs.

Temporal variations in the subsurface velocity field are often (if not always) present in the real world to at least some degree. However, an accounting of their effects on chemical transport has been largely neglected. Here we demonstrate experimentally the effects of a time-varying velocity field on conservative chemical tracer transport in porous media, as compared to constant velocity conditions. We find that velocity-field fluctuations increase chemical tracer spreading and residence time, which intensify the anomalous nature of the transport. This behavior is modeled by a continuous time random walk particle tracking method formulated to account for time-dependent velocity fields. The model matches the experimental results with a parsimonious and consistent set of parameters. The model is then applied to study the effects of different magnitudes in velocity-field fluctuations, as well as different degrees of porous media heterogeneity, on 1-D and 2-D spatiotemporal propagation of an injected, point-source, chemical plume. Increased intensity of velocity-field fluctuations, and increased porous medium heterogeneity, each serve to increase the extent of chemical spreading and anomalous behavior.

We present the synthesis of new composite materials based on copper nanoparticles (Cu NPs) deposited onto montmorillonite (MK10) and quartz sand, for degradation of atrazine, in the context of an advanced oxidation process (AOP). The synthesis involves a first step in which polyethylenimine (PEI) capped Cu NPs (PEI_Cu NPs) are prepared, and then deposited onto, separately, MK10 and sand, through a solvent impregnation method. The resulting products are characterized in detail; the copper is found to exist as a mixture of copper (I, II) oxide. The degradation of atrazine follows a second-order kinetic model with constant values of K2 = 1.7957 g mg−1 min−1 for MK10_PEI_Cu NPs and K2 = 0.8133 g mg−1 min−1 for sand_PEI_Cu NPs. The reaction rate is linked to Cu2O and CuO redox-active species within the layers, pores and surface of the host materials. A degradation mechanism is found with application of these composite materials in the presence of H2O2; adsorption occurs in the absence of H2O2. In contrast, the unmodified MK10 and sand exhibit adsorption in both of the above reaction conditions. Finally, the stability of the Cu NPs following degradation is evaluated, and no significant amount of copper leaching is found.

Copper oxide nanoparticles (CuO-NPs) have been suggested as effective catalysts to degrade many persistent organic contaminants. In parallel, CuO-NPs are considered toxic to soil microorganisms, plants and human cells, possibly because they induce oxidative stress and generation of reactive oxygen species (ROS). However, the mechanism of the catalytic process and the generated ROS are poorly understood. Here we discuss the reaction mechanism of CuO-NPs during the catalytic degradation of enrofloxacin – an antibiotic pharmaceutical used in this study as a representative persistent organic compound. The degradation of an aqueous solution of the enrofloxacin exposed to CuO-NPs and hydrogen peroxide was studied showing fast removal of the enrofloxacin at ambient conditionsns. ROS production was identified by electron spin resonance and a spin trapping technique. The distribution of the free radical species indicated production of a high percentage of superoxide (O2−.) radicals as well as hydroxyl radicals; this production is similar to the “radical production” activity of the superoxide dismutase (SOD) enzyme in the presence of hydrogen peroxide. This activity was also tested in the opposite direction, to examine if CuO-NPs show reactivity that potentially mimics the classical SOD enzymatic activity. The CuO-NPs were found to catalyze the dismutation of superoxide to hydrogen peroxide and oxygen in a set of laboratory experiments.

Reactive chemical transport plays a key role in geological media across scales, from pore scale to aquifer scale. Systems can be altered by changes in solution chemistry and a wide variety of chemical transformations, including precipitation/dissolution reactions that cause feedbacks that directly affect the flow and transport regime. The combination of these processes with advective-dispersive-diffusive transport in heterogeneous media leads to a rich spectrum of complex dynamics. The principal challenge in modeling reactive transport is to account for the subtle effects of fluctuations in the flow field and species concentrations; spatial or temporal averaging generally suppresses these effects. Moreover, it is critical to ground model conceptualizations and test model outputs against laboratory experiments and field measurements. This review emphasizes the integration of these aspects, considering carefully designed and controlled experiments at both laboratory and field scales, in the context of development and solution of reactive transport models based on continuum-scale and particle tracking approaches. We first discuss laboratory experiments and field measurements that define the scope of the phenomena and provide data for model comparison. We continue by surveying models involving advection-dispersion-reaction equation and continuous time random walk formulations. The integration of measurements and models is then examined, considering a series of case studies in different frameworks. We delineate the underlying assumptions, and strengths and weaknesses, of these analyses, and the role of probabilistic effects. We also show the key importance of quantifying the spreading and mixing of reactive species, recognizing the role of small-scale physical and chemical fluctuations that control the initiation of reactions.

Chemical action as an anthropogenic factor in soil formation was suggested 50 years ago as a part of the metapedogenetic process. Initially, agricultural practices such as irrigation with saline water and soil liming by natural carbonated earth materials (marling) were considered as examples of chemical contamination that alter soil properties. Over the years, however, new anthropogenic substances have emerged, and their disposal on the land surface, whether intentionally or by accident, is acting as another metapedogenetic factor, leading to formation of contemporary soils with altered properties. In this context, potential transformation of natural soils may occur as a result of exposure to engineered nanomaterials (ENMs). Due to the relatively small amounts used to date, and their size and associated chemical properties, the impact of ENMs on soil may be questioned. We argue here, however, that ENMs disposed on the land surface are irreversibly retained in the soil matrix, accumulating over time and becoming a metapedogenetic factor. In support of this hypothesis, we present examples from the literature which demonstrate that deposition of carbon-based and metal-based ENMs may cause, under specific conditions, changes to the matrix and properties of soil constituents and formation of contemporary anthropogenic soils. These examples reconfirm the hypothesis that chemicals are a factor in anthropogenically-induced metapedogenesis.

A continuous time random walk particle tracking (CTRW-PT) method was employed to model flow cell experiments that measured transport of engineered nanoparticles (ENPs) in a reactive porous medium. The experiments involved a water-saturated medium containing negatively charged, polyacrylamide beads, resembling many natural soils and aquifer materials, and having the same refraction index as water. Negatively and positively charged ENPs were injected into a uniform flow field in a 3-D horizontal flow cell, and the spatial and temporal concentrations of the evolving ENP plumes were obtained via image analysis. As a benchmark, and to calibrate the model, Congo red tracer was employed in 1-D column and 3-D flow cell experiments, containing the same beads. Negatively charged Au and Ag ENPs demonstrated migration patterns resembling those of the tracer but were slightly more dispersive; the transport was well represented by the CTRW-PT model. In contrast, positively charged AgNPs displayed an unusual behavior: establishment of an initial plume of essentially immobilized ENPs, followed by development of a secondary, freely migrating plume. The mobile plume was found to contain ENPs that, with aging, exhibited aggregation and charge inversion, becoming negatively charged and mobile. In this case, the CTRW-PT model was modified to include a probabilistic law for particle immobilization, to account for the decreasing tendency (over distance and time) of the positively charged AgNPs to attach to the porous medium. The agreement between experimental results and modeling suggests that the CTRW-PT framework can account for the non-Fickian and surface-charge-dependent transport and aging exhibited by ENPs in porous media.

Within historically accepted, major soil-forming major processes, the role of chemicals as a human-induced factor was neglected until the middle of the last century. Over the years, however, anthropogenic chemicals have emerged and are being released on the land surface in large amounts. Irreversible changes in the matrix of soil and soil constituents may occur as a result of both intentional and accidental release of anthropogenic chemicals, as well as a byproduct of human activity. After presenting an historical evolution of the discussion on soil-forming factors, we focus here on human impacts and examine the abiotic role of anthropogenic microchemical contaminant (AMCC) interactions with soils at the molecular level. Selected examples of microchemical contaminants, including heavy metals, pesticides, hydrocarbons, and engineered nanomaterials, are presented to demonstrate that AMCCs-even at low concentration-may irreversibly alter the matrix of the soil and soil constituents and lead to the formation of anthropogenic soils with different properties than those of the pristine soils.

Plastic nanoparticles (PNPs) are considered contaminants of emerging concern, but little information is available on their transport behavior in the soil-water environment, as well as their behavior relative to metal and other carbon-based nanoparticles. Here we show that size and surface functional groups affect the transport of polystyrene nanoparticles (PS-NPs) through saturated soil. Unmodified 110 nm and 50 nm PS-NPs demonstrated similar transport patterns in soil. However, a maximum elution value of 90% from the soil was found for the 50 nm PS-NPs, compared to a maximum value of ∼45% for 110 nm PS-NPs. The breakthrough curve for 190 nm PS-NPs demonstrated a maximum elution value of 60% from the soil. PS-NPs with surface functional groups display different mobility profiles: carboxylated PS-NPs demonstrated a plateau of 40% elution from the soil, while aminated PS-NPs were eluted only in small amounts and showed a spike pattern of elution from the column. These findings are attributed to the effects of common soil constituents such as calcium cations and humic acids on the size and charge of the PS-NPs with surface functional groups. Overall, PS-NP mobility in soil can vary widely, depending on PNP properties such as size and surface chemistry, and on matrix properties, such as the type of porous medium and its composition. These findings suggest that knowledge of inherent characteristics (size, surface charge, surface functional groups) of PNPs are required to elucidate the behavior of such particles in soil-water environments, and predict the extent of contaminant spreading.

Indium and gallium are used widely in modern industry, mostly for the production of semiconductors. They are considered as Technology-Critical Elements and have therefore received growing attention in the past few years. We investigated the influence of different types of humic substances on the transport of indium and gallium in laboratory-scale, saturated column experiments, to gain understanding of their mobility in natural environments. We evaluated the effect of different humic substances on the transport of indium and gallium in quartz sand: a commercial humic acid (Aldrich Humic Acid, AHA), a fulvic acid (Suwannee River Fulvic Acid, SRFA) and an aquatic natural organic matter (Suwannee River Natural Organic Matter, SRNOM). The impact of the flow rate and the influence of different concentrations of organic matter were also investigated. Indium was shown to be more mobile than gallium in the presence of humic substances. The mobility of indium in sand was highest for SRNOM, followed by SRFA and then AHA, while for gallium the order was SRFA > SRNOM > AHA. These results can be significant in understanding the mobility of indium and gallium in soils with various compositions of organic matter.

The use of trace elements to promote biogas production features prominently on the agenda for many biogas-producing companies.However, the application of the technique is often characterized by trial-and-error methodology due to the ambiguous and scarce basic knowledge on the impact of trace elements in anaerobic biotechnologies under different process conditions. This book describes and defines the broad landscape in the research area of trace elements in anaerobic biotechnologies, from the level of advanced chemistry and single microbial cells, through to engineering and bioreactor technology and to the fate of trace elements in the environment. The book results from the EU COST Action on ‘The ecological roles of trace metals in anaerobic biotechnologies’. Trace elements in anaerobic biotechnologies is a critical, exceptionally complex and technical challenge. The challenging chemistry underpinning the availability of trace elements for biological uptake is very poorly understood, despite the importance of trace elements for successful anaerobic operations across the bioeconomy. This book discusses and places a common understanding of this challenge, with a strong focus on technological tools and solutions. The group of contributors brings together chemists with engineers, biologists, environmental scientists and mathematical modellers, as well as industry representatives, to show an up-to- date vision of the fate of trace elements on anaerobic biotechnologies.

This study reports the transport characteristics of the pharmaceutical compounds carboplatin and cisplatin, and their respective derivatives, in saturated sand and soil columns. Pharmaceuticals are recognized as emerging pollutants of soil and water resources, but studies of the transport characteristics of organometallic pharmaceuticals in soil-water environments are rare. A recent study of oxaliplatin transport in natural soil raises the question of whether or not its behavior is representative of all Pt-based pharmaceuticals behavior in soil-water systems. To address this question, transport behaviors of carboplatin and cisplatin species were studied individually in packed sand columns under unamended conditions, and in packed soil columns under unamended and acetate-amended conditions. In contrast to oxaliplatin, carboplatin species exhibited very low affinity to both sand and soil surfaces: the retention of injected carboplatin was 3% and6% for sand and soil, respectively. The affinity to soil was practically the same under the different redox conditions. The affinity of carboplatin to sand and soil surfaces was much smaller than the reported oxaliplatin affinity and the values reported in the literature. Cisplatin exhibited transport behavior similar to that of oxaliplatin in soil, including mild sensitivity to redox conditions (e.g., higher retention under acetate-amended conditions), overall exhibiting retention of 64-70% of the injected species. However, cisplatin also exhibited a similar retention in sand (retention of 45-53%), unlike the cases of carboplatin and oxaliplatin. The results indicate that similarly structured pharmaceuticals can exhibit very different transport characteristic in natural soil-water environments, and should therefore be studied and assessed individually.

The release of pharmaceuticals and personal care products (PPCPs) to the soil-water environment necessitates understanding of PPCP transport behavior under conditions that account for dynamic flow and varying redox states. This study investigates the transport of two organometallic PPCPs, Gd-DTPA and roxarsone (arsenic compound) and their metal salts (Gd(NO3)3, AsNaO2); Gd-DTPA is used widely as a contrasting agent for MRI, while roxarsone is applied extensively as a food additive in the broiler poultry industry. Here, we present column experiments using sand and Mediterranean red sandy clay soil, performed under several redox conditions. The metal salts were almost completely immobile. In contrast, transport of Gd-DTPA and roxarsone was affected by the soil type. Roxarsone was also affected by the different redox conditions, showing delayed breakthrough curves as the redox potential became more negative due to biological activity (chemically-strong reducing conditions did not affect the transport). Mechanisms that include adsorptive retardation for aerobic and nitrate-reducing conditions, and non-adsorptive retardation for iron-reducing, sulfate-reducing and biologically-strong reducing conditions, are suggested to explain the roxarsone behavior. Gd-DTPA is found to be a stable complex, with potential for high mobility in groundwater systems, whereas roxarsone transport through groundwater systems is affected by redox environments, demonstrating high mobility under aerobic and nitrate-reducing conditions and delayed transport under iron-reducing, sulfate-reducing and biologically-strong reducing conditions.

We present quasi-3D visualization and analysis of engineered nanoparticle (ENP) transport behavior in an experimental setup that uses a transmitted light imaging technique. A flow cell was packed with specially adapted, water-transparent, spherical polyacrylamide beads, which carry a negative surface charge representative of many natural environments. Ubiquitous, oppositely-charged ENPs - Au and Ag NPs - were synthesized and introduced into a flow cell subjected to a macroscopically uniform flow field via point source pulse injection, at three different flow rates. The negatively-charged ENPs behaved like a conservative tracer, in terms of spatio-temporal plume evolution. The positive AgNPs, however, displayed a decrease in their initially strong tendency to attach to the oppositely-charged porous medium. As a result, immobilization of the positive AgNPs was spatially and temporally limited to the vicinity of the point of injection; beyond this region, the AgNPs were mobile and effluent contained AgNPs with hydrodynamic diameters significantly larger than those of the injected AgNPs. This behavior is understood by dynamic light scattering and ζ potential measurements, which showed aggregation processes and inversion in particle surface charge to occur during transport of the positive ENPs. These findings have broad implications for ENP mobility and reactivity in the environment.

A large number of research papers on the fate of engineered nanomaterials (ENMs) in the soil-water system have appeared in recent years, focusing on ENM transport, persistence and toxicological impact. It is clear from these publications that soil is a major sink for ENMs, and that only a small portion degrades or is mobilized further into groundwater. However, to date, very few studies have examined the impact of ENMs on the natural soil-subsurface matrix and its properties. Moreover, it is now well accepted that chemical contaminants are capable of changing soil properties either by inducing direct chemical or physical changes, or through indirect changes by, e.g., influencing biological activity that in turn modifies soil properties. Here, we review studies on the deposition, retention, and accumulation of ENMs in soil, indicative of the extent to which soil acts as a major sink of ENMs. We then examine evidence of how these retained particles lead to modification of surface properties, which are manifested by changes in the sorption capacity of soil for other (organic and inorganic) solutes, and by surface charges and composition different than the natural surfaces. Finally, we demonstrate how this results in physical and hydrological changes to soil properties, including hydraulic conductivity, swelling capacity and wettability. The overall picture revealed in this critical review sheds light on a perspective that has received little attention thus far. These aspects of soil change, due to exposure and subsequent accumulation of ENMs, may ultimately prove to be one of the most important impacts of ENM releases to the environment.

Nickel migration measured in laboratory-scale, natural soil column experiments is shown to display anomalous (non-Fickian) transport, nonequilibrium adsorption and desorption patterns, and precipitation/dissolution. Similar experiments using a conservative tracer also exhibit anomalous behavior. The occurrence of ion exchange of nickel, mainly with calcium (but also with other soil components), is measured in both batch and flow-through column experiments; adsorption and desorption isotherms demonstrate hysteresis. Strong retention of nickel during transport in soil columns leads to delayed initial breakthrough (∼40 pore volumes), slow increase in concentration, and extended concentration tailing at long times. We describe the mechanisms of transport and retention in terms of a continuous time random walk (CTRW) model, and use a particle tracking formulation to simulate nickel migration in the column. This approach allows us to capture the non-Fickian transport and the subtle local effects of adsorption/desorption and precipitation/dissolution. Consideration also of preferential pathways accounts for the evolution of the measured breakthrough curve and measured spatial concentration profiles. The model uses non-Fickian transport parameters estimated from the conservative tracer and, as a starting point, adsorption/desorption parameters based on batch experiments and a precipitation parameter based on Ksp values. The batch parameters are found to underestimate the actual amount of adsorption. We suggest that the sorption and precipitation/dissolution dynamics, and resulting breakthrough curves, are influenced strongly by preferential pathways; such pathways significantly alter the availability of sorption sites and ion availability for precipitation. Analysis of these results provides further understanding of the interaction and dynamics among transport, precipitation, and sorption mechanisms in natural soil.

Many of polybrominated organic compounds, used as flame retardant additives, belong to the group of persistent organic pollutants. Compound-specific isotope analysis is one of the potential analytical tools for investigating their fate in the environment. However, the isotope effects associated with transformations of brominated organic compounds are still poorly explored. In the present study, we investigated carbon and bromine isotope fractionation during degradation of tribromoneopentyl alcohol (TBNPA), one of the widely used flame retardant additives, in three different chemical processes: transformation in aqueous alkaline solution (pH 8); reductive dehalogenation by zero-valent iron nanoparticles (nZVI) in anoxic conditions; oxidative degradation by H2O2 in the presence of CuO nanoparticles (nCuO). Two-dimensional carbon-bromine isotope plots (δ(13)C/Δ(81)Br) for each reaction gave different process-dependent isotope slopes (Λ(C/Br)): 25.2 ± 2.5 for alkaline hydrolysis (pH 8); 3.8 ± 0.5 for debromination in the presence of nZVI in anoxic conditions; ∞ in the case of catalytic oxidation by H2O2 with nCuO. The obtained isotope effects for both elements were generally in agreement with the values expected for the suggested reaction mechanisms. The results of the present study support further applications of dual carbon-bromine isotope analysis as a tool for identification of reaction pathway during transformations of brominated organic compounds in the environment.

This study reports the transport characteristics of the organometallic anticancer compound oxaliplatin and its derivatives in natural soil-water environments. Although pharmaceuticals and their derivatives have for many years been detected in water resources, and linked to toxicological impacts on ecological systems, their transport in soil and groundwater is not fully understood. Specifically, studies that describe transport of organometallic pharmaceuticals in porous media are rare, and the transport characteristics of platinum complexes have received little attention. Oxaliplatin transport was studied in sand, as a function of two added natural chelators (citrate and humic acid), and in soil, under four continuously monitored, environmentally-relevant redox conditions: oxic, nitrate reducing, iron reducing and methanogenic. In sand, oxaliplatin species retention was about 7%, and affected only mildly by added citrate, and by humic acid under buffered pH. Transport with unbuffered humic acid was affected significantly by pH variations, and exhibited strong retention at pH

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As a consequence of their growing use in electronic and industrial products, increasing amounts of technology critical elements (TCEs) are being released to the environment. Currently little is known about the fate of many of these elements. Initial research on their potential environmental impact identifies TCEs as emerging contaminants. TCE movement in the environment is often governed by water systems. Research on "natural" waters so far demonstrates that TCEs tend to be associated with suspended particulate matter (SPM), which influences TCE aqueous concentrations (here: concentration of TCEs in dissolved form and attached to SPM) and transport. However, the relative potential of different types of SPM to interact with TCEs is unknown. Here we examine the potential of various types of particulate matter, namely different nanoparticles (NPs; Al2O3, SiO2, CeO2, ZnO, montmorillonite, Ag, Au and carbon dots) and humic acid (HA), to impact TCE aqueous concentrations in aqueous solutions with soil and sand, and thus influence TCE transport in soil-water environments. We show that a combination of NPs and HA, and not NPs or HA individually, increases the aqueous concentrations of TCEs in soil solutions, for all tested NPs regardless of their type. TCEs retained on SPM, however, settle with time. In solutions with sand, HA alone is as influential as NPs+HA in keeping TCEs in the aqueous phase. Among NPs, Ag-NPs and Au-NPs demonstrate the highest potential for TCE transport. These results suggest that in natural soil-water environments, once TCEs are retained by soil, their partitioning to the aqueous phase by through-flowing water is unlikely. However, if TCEs are introduced to soil-water environments as part of solutions rich in NPs and HA, it is likely that NP and HA combinations can increase TCE stability in the aqueous phase and prevent their retention on soil and sand, thus facilitating TCE transport.