A combined approach of electrodialysis pretreatment and vacuum UV for removing micropollutants from natural waters.

Advanced oxidation processes (AOPs) augment traditional water treatment methods, enhancing the removal of persistent contaminants. Efficiency of AOPs that utilize UV radiation for oxidants generation (e.g., ·OH) is reduced in water matrices that contain substants that may act as inner UV filters and/or scavengers for the generated radicals. Among such interfering compounds are major inorganic ions and dissolved organic matter that are naturally present in realistic waters. Thus, to improve AOPs efficiency it is desirable to separate the target pollutants from these natural species before treatment. Here the potential of electrodialysis as such pretreatment was investigated. The impact of this pretreatment on photo-oxidation of the pharmaceutical carbamazepine (CBZ) under VUV (λ<200 nm) irradiation, which yields ·OH generation via water homolysis, was tested in different water matrices. The obtained results indicate that in all tested solutions: Deionized water, groundwater, surface water, and treated wastewater, the addition of electrodialysis pretreatment successfully separated the target micropollutant CBZ from the major natural ions and to some extend the NOM, resulting faster degradation rates of CBZ and its transformation products in the following VUV-based AOP. Energy cost calculations indicated that addition of this pretreatment step reduces the overall energy demand of the system (i.e., energy consumption for the electrodialysis step was smaller than the energy gained by reducing the required VUV irradiation dose).

Hydrothermal processing of polyethylene-terephthalate and nylon-6 mixture as a plastic waste upcycling treatment: A comprehensive multi-phase analysis.

Accumulation of plastic waste is harming eco-systems and it is time to move towards a circular plastic economy. Sustainable production and recycling processes for plastics are challenged mostly by the lack of renewable building blocks. This study investigates hydrothermal processing (HTP) as a platform for depolymerization of two commonly used plastic polymers. Subcritical water (300 °C; 10 MPa) was tested as a solvent to treat polyethylene terephthalate (PET) and nylon-6 individually and in a mixture for a short reaction time of 90 min. Monomer recovery, gaseous emissions, and the effect of polymer mixture were evaluated by comprehensive analyses of all reaction products. Terephthalic acid (TPA), one of two monomers of PET was recovered as a solid product with a mass yield of 75%. ε-caprolactam (CPL), the single monomer of nylon-6 was recovered as a liquid product with a mass yield of 92.5%. Following PET + nylon-6 co-processing, TPA recovery decreased by 20%, whereas CPL recovery was not affected. Since TPA and CPL were recovered in different phases, an easy separation can likely be created for co-processing of PET and nylon-6. While most HTP studies neglect analysis of the gas phase, acetaldehyde and cyclopentene emissions were detected during HTP of PET and nylon-6, respectively. As shown here, gaseous emissions, which may be toxic, should be addressed in future developments of HTP for plastics. The results presented here can contribute to developing HTP processes for plastic recycling, that will be part of a circular plastic economy and a more sustainable future.

H2S Removal from Groundwater by Chemical Free Advanced Oxidation Process Using UV-C/VUV Radiation.

Sulfide species may be present in groundwater due to natural processes or due to anthropogenic activity. H2S contamination poses odor nuisance and may also lead to adverse health effects. Advanced oxidation processes (AOPs) are considered promising treatments for hydrogen-sulfide removal from water, but conventional AOPs usually require continuous chemical dosing, as well as post-treatment, when solid catalysts are applied. Vacuum-UV (VUV) radiation can generate ·OH in situ via water photolysis, initiating chemical-free AOP. The present study investigated the applicability of VUV-based AOP for removal of H2S both in synthetic solutions and in real groundwater, comparing combined UV-C/VUV and UV-C only radiation in a continuous-flow reactor. In deionized water, H2S degradation was much faster under the combined radiation, dominated by indirect photolysis, and indicated the formation of sulfite intermediates that convert to sulfate at high radiation doses. Sulfide was efficiently removed from natural groundwater by the two examined lamps, with no clear preference between them. However, in anoxic conditions, common in sulfide-containing groundwater, a small advantage for the combined lamp was observed. These results demonstrate the potential of utilizing VUV-based AOP for treating H2S contamination in groundwater as a chemical-free treatment, which can be especially attractive to remote small treatment facilities.

Gaseous pollutant transport from an underground parking garage in a Mediterranean multi-story building-Effect of temporal resolution under varying weather conditions.

Indoor air dynamics and quality in high density residential buildings can be complex as it is affected by both building parameters, pollution sources, and outdoor meteorological conditions. The present study used CONTAM simulations to investigate the intra-building transport and concentration of an inert pollutant continuously emitted from an underground garage of a 15-floor building under moderate Mediterranean weather. The effects of outdoor meteorological conditions (air temperature, wind speed and direction) on indoor distribution of the emitted pollutant was tested under constant conditions. The importance of using actual transient meteorological data and the impact of their temporal resolution on calculated concentrations and exposure levels were also investigated. Vertical profiles of air exchange rate (AER) and CO concentration were shown to be sensitive to indoor-outdoor temperature difference, which controls the extent of the stack effect and its importance relative to wind effect. Even under constant conditions, transient mode simulations revealed that the time needed for pollutant distribution to reach steady state can be quite long (>24h in some cases). The temporal resolution (1h vs. 8h) of the meteorological data input was also found to impact calculated exposure levels, in an extent that varied with time, meteorological conditions and apartment position.

Does polyacrylamide-based adjuvant actually reduce primary drift of airborne pesticides?

Atmospheric drift of pesticides sprayed outside treated fields may pose serious environmental and health concerns. Chemical adjuvants, among other techniques, reduce drift by modifying the physicochemical properties of the pesticide solution, which presumably produces larger droplets upon spraying that are less prone to drift. Previous studies, that have addressed the effect of adjuvants on drift reduction, mainly rely on measurements of droplet sedimentation while ignoring the presence of pesticides in the forms of small aerosols and vapor. Such forms are expected to be highly susceptible to atmospheric drift that may pose human health risk via inhalation exposure. The present study examines the effect of a polymer-based adjuvant on airborne-pesticide drift using active air sampling in two field campaigns. Surprisingly, these measurements indicate higher primary drift (PD) of airborne pesticides in the presence of adjuvant in the spraying solution. The results are further supported by comparing measured drifts to those calculated using a modified Gaussian puff dispersion model, which enabled to evaluate the impact of varying meteorological conditions during the field experiments. In addition, the adjuvant effect on droplet size distribution generated by common nozzles, was tested in a wind tunnel. The resulting size-distributions demonstrated that while the addition of adjuvant resulted in a desired shift of the volumetric distribution towards larger droplets, it also led to a significant increase in the number concentration of fine droplets. Such trends can explain how the addition of polymeric adjuvant can yield both, a reduction in sedimenting drift outside treated areas and an increase in airborne PD intensity, as observed in the present study. This study demonstrates the complex effect of chemical adjuvants and the urgent need to further explore and understand their environmental impact.

Removal of organic micropollutants from biologically treated greywater using continuous-flow vacuum-UV/UVC photo-reactor.

Despite growing apprehension regarding the fate of organic micropollutants (MPs) of emerging concern, little attention has been paid to their presence in domestic greywater, where they mainly originate from personal care products. Many MPs are not fully removed in conventional greywater treatments and require additional treatment. Vacuum-UV radiation (VUV) can generate ·OH in situ, via water photolysis, initiating advanced oxidation process (AOP) without any chemical addition. Despite growing interest in VUV-based AOP, its performance in real-life grey- or wastewater matrices has hardly been investigated. The present study investigates the removal of triclosan (TCS) and oxybenzone (BP3), common antibacterial and UV-filter MPs, in deionized water (DIW) and in treated greywater (TGW) using combined UVC/VUV or UVC only radiation in a continuous-flow reactor. Degradation kinetics of these MPs and their transformation products (TPs) were addressed, as well as bacterial growth inhibition of the resulting reactor's effluent. In DIW, MP degradation was much faster under the combined UVC/VUV irradiation. In TGW, the combined radiation successfully removed both MPs but at lower efficiency than in DIW, as particles and dissolved organic matter (DOM) acted as radical scavengers. Filtration and partial DOM removal prior to irradiation improved the process efficiency and reduced energy requirements under the combined radiation (from 1.6 and 167 to 1.1 and 6.0 kWh m-3·Ö¼order-1 for TCS and BP3, respectively). VUV radiation also reduced TP concentrations in the effluent. As a result, bacterial growth inhibition of triclosan solution irradiated by VUC/VUV was lower than that irradiated by UVC light alone, for UV dose > 120 mJ cm-2.

Direct tracing of NH3 and N2O emissions associated with urea fertilization approaches, using static incubation cells.

Nitrogen fertilization contributes significantly to crop production globally. However, low efficiency application management approaches lead to substantial N losses of which ammonia and nitrous oxide are known as environmental threats. Urea, the largest N fertilization source globally, is associated with high ammonia losses. A large variety of application modes are practiced under different environmental conditions worldwide. Yet, the complexity of N-processes in different soils, under changing agro-environmental conditions, challenges the evaluation of fertilization approaches efficiency in reducing N-gaseous losses. In this research a simply designed static incubation cell was connected to a Long-Path gas cell and a Fourier Transform IR spectrometer (LP-FTIR), allowing online determination of ammonia and nitrous oxide emissions in parallel to tracking mineral N-dynamics in soil samples. The static chamber was used to evaluate different application approaches of urea (i.e., incorporation or surface application with or without wetting) in a Sandy Loam and to compare surface applied regular urea vs. urea amended with the urease inhibitors NPPT+NBPT [N-(n-butyl) thiophosphoric triamide and N-(n-propyl) thiophosphoric triamide, respectively] in four different representative soils. Ammonia emissions peaked few days after application, where highest losses were observed for surface application mode. Highest emissions, up to 5% (w/w) of applied Urea-N, were obtained with the lighter and more basic soils (Sandy Loam and Loess; pH > 7.9). Nitrous oxide emissions showed a lag period of ~1 week and were higher under lower urea application rates, and when nitrification was faster (~1-1.3% (w/w) of applied N). Urease inhibitors significantly reduced ammonia losses in all tested soils and particularly in the Sandy Loam and Loess. Their effect on nitrous oxide losses were observed with the Sandy Loam and particularly after 2 weeks. The static system may underestimate realistic ammonia losses, but it offers a rather simply operated system, providing information about N-gaseous losses for improving N-fertilization management.

Seasonal variations of polybrominated flame retardants bound to car dust under Mediterranean climate.

Polybrominated diphenyl ethers (PBDEs) are commercial flame retardants that have been commonly used in vehicle interior to reduce fire-related hazards. Due to high temperatures and intense insolation that can be attained inside cars parked in the sun, additive PBDEs are prone to leach out and attach to in-vehicle dust, as well as to photo-debrominate. This study examines seasonal variations of concentrations of three common PBDE congeners (BDE-47, BDE-99 and BDE-209) in car dust in Israel. The overall concentrations of these BDEs ranged from 1 to 29µg/g, and were higher in the summer than in the winter (average of 10.2 and 5.3µg/g, respectively). Congener-specific concentrations showed distinct seasonal pattern, representing the interplay between leaching, evaporation and photodebromination. Photolysis of the three congeners, while adsorbed on glass filters and exposed to solar radiation, revealed first order kinetics with debromination rates on the order of 10-2/min. Hence, seasonal variations of the meteorological conditions were found to affect the in-vehicle PBDE concentrations, and are therefore expected also to affect the exposure of passengers to PBDEs.

Sorption and biodegradation of propylparaben in greywater by aerobic attached-growth biomass.

Greywater (GW) is becoming an important alternative water source for non-potable purposes, but requires treatment to remove contaminants, including micropollutants that in GW mainly originate from personal care products. Biofilters are commonly used for onsite GW treatment, but there are still significant knowledge gaps regarding their ability and mechanism of micropollutants removal. This study investigates the removal of propylparaben (PPB) by aerobic attached-growth biomass, quantifying the kinetics and the interplay between sorption and biodegradation. The ability of biomass, collected from a pilot scale biofilter treating real GW, to eliminate PPB from both synthetic greywater (SGW) and deionized (DI) water was studied in laboratory batch experiments. Elimination of PPB was found to proceed via sorption to biomass followed by biodegradation. Sorption of PPB by biomass in SGW and in DI water exhibited similar kinetics, fitting Langmuir isotherm with the maximum adsorbed amount of 9.8mgPPB gbiomass-1. PPB biodegradation exhibited first-order kinetics in both SGW and DI water, with a 30h lag-phase in SGW and no lag-phase in DI water. This difference is attributed to presence of readily-biodegradable organic matter in the SGW. Actual PPB degradation rate in both cases (excluding the lag phase in SGW) was very similar, 62mgPPB gbiomass-1d-1, yielding almost full mineralization. These findings show the relative contribution of the major processes involved in PPB elimination by biofilters and can be applied for designing GW treatment units.

Primary and secondary pesticide drift profiles from a peach orchard.

Atmospheric drift is considered a major loss path of pesticide from target areas, but there is still a large gap of knowledge regarding this complex phenomenon. Pesticide drift may occur during application (Primary drift) and after it (Secondary drift). The present study focuses on primary and secondary drift from ground applications in peach orchard (tree height of 3 m), under Mediterranean climate. Detailed and prolonged vertical drift profiles at close proximity to orchard are presented, together with detailed measurements of key meteorological parameters. The effect of volatility on drift was also studied by simultaneously applying two pesticides that differ in their volatility. Drifting airborne pesticides were detected both during and after applications at sampling distances of 7 and 20 m away from orchard edge. Concentrations ranged between hundreds ng m-3 to a few µg m-3 and showed clear decrease with time and with upwind conditions. Almost no decline in concentrations with height was observed up to thrice canopy height (i.e., 10 m). These homogeneous profiles indicate strong mixing near orchard and are in line with the unstable atmospheric conditions that prevailed during measurements. While air concentrations during pesticide application were higher than after it, overall pesticide load drifted from the orchard during primary and secondary drift are comparable. To the best of our knowledge this is the first work to show such large vertical dispersion and long duration of secondary drift following ground application in orchards. The obtained information indicates that secondary drift should not be neglected in exposure and environmental impact estimations.

The Essential Role for Laboratory Studies in Atmospheric Chemistry.

Laboratory studies of atmospheric chemistry characterize the nature of atmospherically relevant processes down to the molecular level, providing fundamental information used to assess how human activities drive environmental phenomena such as climate change, urban air pollution, ecosystem health, indoor air quality, and stratospheric ozone depletion. Laboratory studies have a central role in addressing the incomplete fundamental knowledge of atmospheric chemistry. This article highlights the evolving science needs for this community and emphasizes how our knowledge is far from complete, hindering our ability to predict the future state of our atmosphere and to respond to emerging global environmental change issues. Laboratory studies provide rich opportunities to expand our understanding of the atmosphere via collaborative research with the modeling and field measurement communities, and with neighboring disciplines.

Key environmental processes affecting the fate of the insecticide chloropyrifos applied to leaves.

Chlorpyrifos (CP) is still a commonly employed organophosphorus insecticide worldwide. In semi-arid and Mediterranean climates, applied CP is expected to remain on leaves surfaces for relatively long time due to the lack of summer rains and common use of drip irrigation. The present work examines the loss rate of CP from leaves via different surface processes: evaporation, direct photolysis and reactions with ozone and OH radicals. Laboratory experiments showed that evaporation rate constant of CP increased from 0.109 to 0.492 h-1 with the increase in wind speed up to 4 m/s. First-order rate constant of direct photolysis, measured using a solar simulator, was k'UV = 1.15 (±0.01) x 10-20 cm2 photon-1. Second-order rate constants for the reaction of CP with ozone and OH were measured as 6 × 10-20 and 6 × 10-12 cm3 molecule-1 s-1, respectively. The above rate constants were applied successfully in an outdoor experiment to predict the disappearance of chloropyrifos under specific environmental conditions. Further modeling showed that the insecticide half-life time on exposed surfaces under typical Mediterranean environment will be in the range of 0.9-6.9 h. Evaporation is expected to be the dominant removal path under most environmental conditions, followed by direct photolysis and reaction with OH.

Detection and quantification of water-based aerosols using active open-path FTIR.

Aerosols have a leading role in many eco-systems and knowledge of their properties is critical for many applications. This study suggests using active Open-Path Fourier Transform Infra-Red (OP-FTIR) spectroscopy for quantifying water droplets and solutes load in the atmosphere. The OP-FTIR was used to measure water droplets, with and without solutes, in a 20 m spray tunnel. Three sets of spraying experiments generated different hydrosols clouds: (1) tap water only, (2) aqueous ammonium sulfate (0.25-3.6%wt) and (3) aqueous ethylene glycol (0.47-2.38%wt). Experiment (1) yielded a linear relationship between the shift of the extinction spectrum baseline and the water load in the line-of-sight (LOS) (R(2) = 0.984). Experiment (2) also yielded a linear relationship between the integrated extinction in the range of 880-1150 cm(-1) and the ammonium sulfate load in the LOS (R(2) = 0.972). For the semi-volatile ethylene glycol (experiment 3), present in the gas and condense phases, quantification was much more complex and two spectral approaches were developed: (1) according to the linear relationship from the first experiment (determination error of 8%), and (2) inverse modeling (determination error of 57%). This work demonstrates the potential of the OP-FTIR for detecting clouds of water-based aerosols and for quantifying water droplets and solutes at relatively low concentrations.

Reconstruction of passive open-path FTIR ambient spectra using meteorological measurements and its application for detection of aerosol cloud drift.

Remote sensing of atmospheric aerosols is of great importance to public and environmental health. This research promotes a simple way of detecting an aerosol cloud using a passive Open Path FTIR (OP-FTIR) system, without utilizing radiative transfer models and without relying on an artificial light source. Meteorological measurements (temperature, relative humidity and solar irradiance), and chemometric methods (multiple linear regression and artificial neural networks) together with previous cloud-free OP-FTIR measurements were used to estimate the ambient spectrum in real time. The cloud detection process included a statistical comparison between the estimated cloud-free signal and the measured OP-FTIR signal. During the study we were able to successfully detect several aerosol clouds (water spray) in controlled conditions as well as during agricultural pesticide spraying in an orchard.

Particle dynamics and deposition in true-scale pulmonary acinar models.

Particle transport phenomena in the deep alveolated airways of the lungs (i.e. pulmonary acinus) govern deposition outcomes following inhalation of hazardous or pharmaceutical aerosols. Yet, there is still a dearth of experimental tools for resolving acinar particle dynamics and validating numerical simulations. Here, we present a true-scale experimental model of acinar structures consisting of bifurcating alveolated ducts that capture breathing-like wall motion and ensuing respiratory acinar flows. We study experimentally captured trajectories of inhaled polydispersed smoke particles (0.2 to 1 µm in diameter), demonstrating how intrinsic particle motion, i.e. gravity and diffusion, is crucial in determining dispersion and deposition of aerosols through a streamline crossing mechanism, a phenomenon paramount during flow reversal and locally within alveolar cavities. A simple conceptual framework is constructed for predicting the fate of inhaled particles near an alveolus by identifying capture and escape zones and considering how streamline crossing may shift particles between them. In addition, we examine the effect of particle size on detailed deposition patterns of monodispersed microspheres between 0.1-2 µm. Our experiments underline local modifications in the deposition patterns due to gravity for particles ≥0.5 µm compared to smaller particles, and show good agreement with corresponding numerical simulations.

Degradation of VX surrogate profenofos on surfaces via in situ photo-oxidation.

Surface degradation of profenofos (PF), a VX nerve gas surrogate, was investigated using in situ photo-oxidation that combines simple instrumentation and ambient gases (O2 and H2O) as a function of exposure conditions ([O3], [OH], UV light λ = 185 and/or 254 nm, relative humidity) and PF film surface density (0.38-3.8 g m(-2)). PF film 0.38 g m(-2) fully degraded after 60 min of exposure to both 254 and 185 nm UV light in humidified air and high ozone. The observed pseudo-first-order surface reaction rate constant (kobs = 0.075 ± 0.004 min(-1)) and calculated hydroxyl concentration near the film surface ([OH]g = (9 ± 2) × 10(7) molecules cm(-3)) were used to determine the second-order rate constant for heterogeneous reaction of PF and OH (k(OH)PF = (5 ± 1) × 10(-12) cm(3) molec(-1) s(-1)). PF degradation in the absence of 185 nm light or without humidity was lower (70% or 90% degradation, respectively). With denser PF films ranging from 2.3 to 3.8 g m(-2), only 80% degradation was achieved until the PF droplet was redissolved in acetonitrile which allowed >95% PF degradation. Surface product analysis indicated limited formation of the nontoxic phosphoric acid ester but the formation of nonvolatile chemicals with increased hydrophilicity and addition of OH.

Synergetic effect between photocatalytic degradation and adsorption processes on the removal of phenolic compounds from olive mill wastewater.

The photocatalytic degradation of two phenolic compounds, p-coumaric acid and caffeic acid, was performed with a suspended mixture of TiO(2) and powdered activated carbon (PAC) (at pH=3.4 and 8). Adsorption, direct photolysis and photocatalytic degradation were studied under different pH and UV light sources (sunlight vs. 365nm UV lamps). The potential for reusing this catalyst mixture in sequential photocatalytic runs was examined as well. Quantum yields for the direct photolysis of caffeic acid under solar and artificial 365nm light were calculated (for the first time) as 0.005 and 0.011, respectively. A higher removal rate of contaminants by either adsorption or photocatalysis was obtained at a low pH (pH 4). Furthermore, the addition of PAC increased the removal efficiency of the phenolic compounds. Fast removal of the pollutants from the solution over three sequential runs was achieved only when both TiO(2) and PAC were present. This suggests that at medium phenolic concentrations, the presence of PAC as a co-sorbent reduces surface poisoning of the TiO(2) catalyst and hence improves photocatalysis degradation of phenolic pollutants. The adsorption equilibrium of caffeic acid or p-coumaric acid on TiO(2), PAC and the combined mixture of TiO(2) and PAC follows the Langmuir isotherm model. Experiments with PAC TiO(2) mixture and olive mill wastewater (anaerobically treated and diluted by a factor of 10) showed higher removal of polyphenols than of chemical oxygen demand (COD). 87% removal of total polyphenols, compared to 58% of COD, was achieved after 24h of exposure to 365nm irradiation (7.6W/m(2)) in the presence of a suspended mixture of TiO(2) and PAC, indicating "self-selectivity" of polyphenols.

Chemical stability and extent of isomorphous substitution in ferrites precipitated under ambient temperatures.

The ferrite process is an established method for treating wastewaters containing dissolved toxic metals, using precipitation at temperatures above 65 °C. Various ambient-temperature operation methodologies have also been proposed, but the effects of temperature reduction on product stability, and on the extent of isomorphous substitution (in terms of x in Me(x)Fe(3-x)O(4), Me representing a non-iron metal), have not been adequately quantified. At ambient temperature precipitation, maximal x of Zn(2+), Co(2+), Ni(2+) and Cd(2+) was found in the current study to be approximately 0.73, 0.67, 0.39 and 0.17, respectively. These values are 73% to 50% of the corresponding values attained by precipitation at 90 °C. The chemical stability of the ferrites produced under ambient temperatures was found to deteriorate upon high Me(2+) incorporation levels, in stark contrast with the trend observed in ferrites precipitated at 90 °C. Both observations were ascribed to the increased importance of Fe(2+)-Fe(3+) interaction under ambient conditions in driving spinel ordering. In the presence of high Me to Fe ratio in the initial solution, this interaction is weaker, resulting in impeded dehydration.

Fuel derived pollutants and boating activity patterns in the Sea of Galilee.

MTBE (Methyl tert-Butyl Ether) is a fuel additive that replaced lead as an antiknock compound in internal combustion motors. Few years after its introduction, detectable levels of MTBE were found in various water bodies. MTBE has a very low taste and odor threshold and is a potential carcinogen. Another group of fuel derived toxic compounds that has been detected in water bodies is BTEX (Benzene, Toluene, Ethylbenzene and Xylene). Boating activity and allochthonous contributions from watersheds are the major sources of fuel derived pollutants in lakes. Their concentrations in lakes thus vary as a function of boating activity intensity, lake surface area and depth, weather and wind regime, land-use in the watershed, etc. The Sea of Galilee (Lake Kinneret) is the only recreational lake in Israel and an important freshwater source. In the current study, a sampling campaign was conducted in order to quantify MTBE and BTEX concentrations in Lake Kinneret, its marinas and its main contributing streams. In addition, a boating-use survey was performed in order to estimate MTBE and BTEX contribution of recreational boating. The sampling campaign revealed that, as expected, MTBE concentrations were higher than BTEX, and that near shore (i.e., marina) concentrations were higher than in-lake concentrations. Despite the clear contribution from boating, high MTBE concentrations were found following a major inflow event in winter, indicating the importance of the allochthonous contribution. The contribution from boating during summer, as measured indirectly by in-lake concentrations, is likely underestimated due to enhanced MTBE volatilization due to strong winds and high temperatures. May-September was found to be the main recreational boating season, with continued boating year round. On average, a single boat is active 23 d/y, with 84% of the watercrafts being active only during weekends and holidays. The survey further indicated that boats stay in the lake for 4.5 h on average, which conforms to the unique winds regime that limits afternoon activity due to high winds, and have an average fuel consumption of 14 L/h. The annual load of MTBE and BTEX from recreational boating in Lake Kinneret was estimated at 4430 and 6220 kg/y respectively.

Extent and mechanism of metal ion incorporation into precipitated ferrites.

The ability of many noniron metals to be incorporated into the structure of ferrites is being utilized in numerous industrial and environmental applications. The incorporation of some of these metals during Fe(II) oxidation-induced precipitation at moderate temperatures (80-100°C) appears to be limited, for reasons not fully understood, and to extents not always agreed (e.g., Ni(2+), Cr(3+)). In this paper, the incorporation maxima of six metals into the structure of precipitated ferrites (in terms of x in Me(x)Fe(3-)(x)O(4), Me represents a noniron metal) were concluded to be 1.0, 1.0, 0.78, 0.49, 0.35, and 0.0 for Zn(2+), Co(2+), Ni(2+), Al(3+), Cd(2+) and Cr(3+), respectively. With the exception of the much larger Cd(2+), these values were associated with kinetic considerations controlled by the H(2)O exchange rate between the hydration shells surrounding the dissolved metal ion.