Log Kow Values Research Articles

Accumulation and passive sampling of bisphenol analogues using triolein-embedded cellulose acetate membrane in waters

Bisphenol analogues (BPs) are emerging contaminants that have been widely detected in water environments. The presence of substituted hydrophilic and hydrophobic groups in the molecule may lead to unclear performance in passive sampling. This study tested the accumulation capacity and passive sampling of fifteen BPs in a triolein-embedded cellulose acetate membrane (TECAM) passive sampler. In a dynamic accumulation experiment, twelve hydrophobic BPs accumulated in the TECAM with concentrations ranging from 251 ng g−1 to 6283 ng g−1, and three hydrophilic BPs did not accumulate during the 72 h exposure duration. BPs accumulations were determined by the hydrophilic and hydrophobic substituent groups in molecule structures. The estimated passive sampling parameters showed correlations to both the log Kow values and chemical structures, and compared to other contaminants, such as organophosphorus flame retardants. Environmental factors, including flow rate, temperature, salinity, and pH, that affect the accumulation of BPs in the TECAM were tested, and the flow rate was found to be an important factor affecting the uptake rate. The isotropic exchange kinetics for BPs in the TECAM were verified, and the results indicated that BPs can be calibrated with performance reference compounds (PRCs) in field applications. Finally, a field deployment of TECAM in river waters successfully estimated the time-weighted concentrations of two hydrophobic BPs. To address the inherent weaknesses of TECAM in sampling hydrophilic and moderately hydrophobic BPs, future studies should explore alternative passive samplers, such as hydrophilic-lipophilic balance sorbent-embedded cellulose acetate membranes, to sample BPs in surface waters.

Estimation of octanol-water partition coefficients of PCBs based on the solvation free energy

In the present study, the thermodynamic relationship between log KOW and the solvation free energy from water to octanol (ΔGOW) was employed to estimate log KOW of PCBs. HF/MIDI!6D was identified to be the optimal calculation level for both the geometry optimization and energy calculation. Based on the optimal calculation level, ΔGOW values were calculated and used to estimate the log KOW values of PCBs. It was found that the intermolecular interactions of PCBs in the aqueous phase and octanol phase were similar, resulting in different effects of the dimer on the estimation of log KOW of PCBs from that on log KOA of PCBs. Compared with other reported models, the ΔGOW model had comparable goodness-of-fit and predictive ability, and a more universal application domain. Therefore, the solvation free energy method could be a promising method for the prediction of KOW.

Polyethylene mesh knitted fabrics mulching the soil to mitigate China's haze: A potential source of PBDEs

The fate of polybrominated diphenyl ethers (PBDEs) from polyethylene mesh knitted fabrics (PMKFs) to mulched soil and nearby plants was studied. PBDEs in the soil sample collected from Tianjin University of Commerce in April 2019 increased significantly after 6 months of PMKF mulching owing to PMKFs as the main input source. The compositional profiles/congener patterns of the PBDEs in the soil and PMKFs became similar after 6 months. High correlations were found between ΣPBDEs in the soil and PMKFs in October 2019, with no significant correlation in April. Plants could take up, accumulate and biotransform PBDEs in contaminated soil. The uptake of BDE-209 by plants was the highest compared with other lesser brominated PBDE congeners, due to its higher log Kow value and molecular weight or size. BDE-47 taken up in the plant was biotransformed via hydroxylation. These results prove that the government's PMKF solution to haze is causing environmental problems in bare soil, i.e., PBDE pollution in both soil and nearby plants. The present study provides important pieces of evidence for government and policymakers, and it is recommended that one environmental problem is not solved by creating another.

From suspect screening to target analysis: Occurrence of six newly identified compounds in indoor dust from Belgium

Six newly identified compounds, dimethyl azelate (DMA), dimethyl sebacate (DMS), di-propylene glycol dibenzoate (DiPGDB), tri-n-butyl trimellitate (TBTM), isooctyl 2-phenoxyethyl terephthalate (IOPhET) and bis-3,5,5-trimethylhexyl phosphate (TMHPh), were quantified in residential dust using a modified and in-house validated method. The method was based on vortex and ultrasonic extraction, Florisil fractionation and liquid chromatography with tandem mass spectrometry (LC-MS/MS) analysis. Fifty paired dust samples were collected from homes located in the Flemish region of Belgium, during winter (n = 25) and summer (n = 25) of 2019. Method LOQs ranged between 3.8 and 94 ng/g. The ranges of total concentrations of targeted compounds were 0.6–89 μg/g for winter and 0.8–130 μg/g for summer samples. DiPGDB was the dominant compound, with 88% and 92% contribution in dust samples per season, followed by TBTM > TMHPh > DMA (less than 10% contribution in both seasons) and DMS, detected only in the summer samples. Human exposure was evaluated for inadvertent dust ingestion using the oral derived no effects level values (DNEL) where available in ECHA, for (I) the hypothesis, where the total concentration of the chemical is considered bio-accessible, (II) the hypothesis where the bio-accessible fraction is defined by the theoretical bio-accessibility, calculated based on logKow values. In both scenarios, DiPGDB, TBTM and TMHPh had the most important contribution to human exposure, with toddlers being more exposed than adults. No risk for adverse human health effects was derived from the comparison with DNELs.

Bioaccumulation of legacy organic contaminants in pregnant Indo-Pacific humpback dolphins (Sousa chinensis): Unique features on the transplacental transfer

The placental transfer and congener composition of organic contaminants (OCs) in Indo-Pacific humpback dolphins have been little studied. In the present study, 16 polycyclic aromatic hydrocarbons (PAHs), 18 organochlorine pesticides (OCPs), and 28 polychlorinated biphenyl (PCB) congeners were analyzed in muscle, lung, liver, kidney, and blubber tissues from three mother–fetus pairs of this species stranded along the Pearl River Estuary, China. For PCBs, tetra-, penta-, hexa-, and hepta-chlorobenzene congeners were dominant in all the analyzed samples. Among them, hexachlorobenzene congeners showed the highest level in most dolphin mother-fetus tissue samples. The concentrations of PCBs and OCPs in adult females were higher in the detoxification organs (liver and kidneys) than in the muscles and lungs, whereas muscle tissues in fetuses generally exhibited higher PCBs and OCPs levels than the livers and kidneys. The most abundant PAHs in the four tissues were those with lower molecular weights, which were also the most water-soluble and bioavailable. Negative correlations between the octanol/water partition coefficients (log KOW) and the fetus/mother ratios for PCB congeners revealed that the transfer of PCBs may be determined by their lipid solubility. OCPs and PCBs with low molecular weights and low log KOW values would be more likely to accumulate in the dolphin liver, lung, kidney and muscle tissues. Furthermore, OCs with low molecular weights and low log KOW values were more concentrated in the fetal blubber, lung, and liver tissues than in their respective mothers. The ubiquitous existence of OCs in the mother–fetus pairs strongly suggested that these contaminants could pass through the placenta and partition in fetal tissue. The high transfer efficiency of PAHs and PCBs indicated that the placenta might not be an efficient barrier for these pollutants. PCBs levels in both mother and fetus dolphins could cause immunosuppression.

Sorption of micropollutants to hydroponic substrata: Effects of physico-chemical properties

Constructed wetlands could be improved with novel substrata to enhance the removal efficiency of micropollutants from wastewater and reduce the spatial footprint. Use of hydroponic substrata like mineral wool, pumice, wood - and coconut fibre is both novel for wastewater treatment, and potentially suitable, due to their hydraulic compatible texture. Since sorption is a key removal process for pollutants in constructed wetlands, this study investigates sorption to novel substrata by six priority micropollutants, caffeine, carbamazepine, ibuprofen, naproxen, sulfamethoxazole and trimethoprim, with diverse Log Kow and pKa values. We found that higher sorption was positively related to substrata's organic matter content. Organic substrata, namely wood - and coconut fibre, demonstrated higher sorption affinity compared with the inorganic substrata mineral wool and pumice, notably regardless of the micropollutants’ Log Kow. Carbamazepine efficiently and rapidly sorbed onto organic substrata, which is particularly noteworthy considering the recalcitrance of carbamazepine in conventional treatment plants. The sorption isotherms were best described by the Freundlich model rather than Langmuir or linear models. We determined that using wood fibre in constructed wetlands would require around 35–66% less area to remove the selected micropollutants, compared to soil as matrix. Thus our results show the potential of using hydroponic substrata such as wood - and coconut fibre to both remove micropollutants in, and reduce the footprint of constructed wetlands.

Brominated flame retardants (BFRs) in marine food webs from Bohai Sea, China

In this study, brominated flame retardants (BFRs), including 13 polybrominated diphenyl ethers (PBDEs) and 17 novel brominated flame retardants (NBFRs) are determined in 18 species (including plankton, invertebrate, and fish) from Bohai Sea, China. Trophic transfer of these compounds is also assessed in the marine food web.Significant trophic magnification (p < 0.01) for 11 PBDE congeners (BDE-17, BDE-28, BDE-47, BDE-49, BDE-66, BDE-85, BDE-99, BDE-100, BDE-153, BDE154 and BDE-183) is observed. No significant correlation is observed for BDE-138 (p = 0.06), and significant trophic dilution is observed for BDE-209 (p < 0.0001). In PBDEs, BDE-66 has the highest TMF value of 3.9 (95% confidence interval (CI): 3.2–4.7), followed by BDE-47 (TMF: 3.8, 95% CI: 2.6–5.4) and BDE-28 (3.0, 2.2–4.1). For NBFRs, ATE, TBECH (include α- and β-isomer), PBBZ, TBCO (include α- and β-isomer), PBT, DPTE, HBBZ, PBBA, BTBPE, PBEB and HCDBCO are observed significant trophic magnification (p < 0.01), significant trophic dilution is observed for BATE (p < 0.01), DBDPE (p < 0.001) and OBIND (p < 0.0001), no significant correlation is observed for p-TBX (p = 0.77). In NBFRs, PBT has the highest TMF value of 4.5 (95% CI: 3.1–6.3), followed by PBEB (TMF: 4.0, 95% CI: 2.1–7.6) and HCDBCO (3.9, 3.1–5.0). Regression analysis between KOW and TMF values of BFRs suggest that TMF values have a trend of first rising and then falling against the values of log KOW. Generally, chemicals with higher KOW value have stronger trophic magnification capacity than those with lower ones, but due to the influence of bioavailability, the trophic magnification ability of the superhydrophobic compounds may be inhibited. To our best knowledge, this is the first report of trophic transfer of NBFRs in marine food web and trophic transfer of 9 NBFRs (α-TBECH, p-TBX, BATE, PBBZ, α-TBCO, β-TBCO, DPTE, OBIND, and HCDBCO) in aquatic food web.

Plant uptake and soil fractionation of five ether-PFAS in plant-soil systems

Considering the grave concerns caused by conventional per- and polyfluorinated substances (PFAS), production and use of fluoroalkylether compounds (ether-PFAS) have been on the rise. These ether-PFAS are deemed as PFAS replacement chemicals. To understand distribution of ether-PFAS in plant-soil systems, we investigated plant uptake of five selected ether-PFAS (i.e., PFMOPrA, PFMOBA, GenX, ADONA, F53B) by Carex comosa (longhair sedge) and the fractionation of these compounds in soil. Our results demonstrated that all five ether-PFAS in this study were taken up by C. comosa and translocated to plant shoots to different extents. Exposure concentration and time both positively affected plant uptake of ether-PFAS. Unlike the other four ether-PFAS, F53B with the longest carbon chain length and a sulfonic functional group was largely accumulated in C. comosa roots with limited translocation to plant shoots. Results from sequential extractions revealed that the five ether-PFAS had different distributions in soil with regard to extractable by water, basic methanol, acidic methanol and non-extractable. Concentration of ether-PFAS in water-soluble fraction increased with decreasing carbon chain length and logKow values and had a positive linear relationship with the mass of ether-PFAS in plant shoots (R2 = 0.64) and in whole plants (R2 = 0.94). Our results also indicated that the aging process could facilitate ether-PFAS to become non-extractable, hence reducing their mobility in soil and bioavailability to plants.

Passive sampler phases for pesticides: evaluation of AttractSPE\u2122 SDB-RPS and HLB versus Empore\u2122 SDB-RPS

In this study, three different passive sampling receiving phases were evaluated, with a main focus on the comparability of established styrene-divinylbenzene reversed phase sulfonated (SDB-RPS) sampling phase from Empore™ (E-RPS) and novel AttractSPE™ (A-RPS). Furthermore, AttractSPE™ hydrophilic-lipophilic balance (HLB) disks were tested. To support sampling phase selection for ongoing monitoring needs, it is important to have information on the characteristics of alternative phases. Three sets of passive samplers (days 1–7, days 8–14, and days 1–14) were exposed to a continuously exchanged mixture of creek and rainwater in a stream channel system under controlled conditions. The system was spiked with nine pesticides in two peak scenarios, with log KOW values ranging from approx. − 1 to 5. Three analytes were continuously spiked at a low concentration. All three sampling phases turned out to be suitable for the chosen analytes, and, in general, uptake rates were similar for all three materials, particularly for SDB-RPS phases. Exceptions concerned bentazon, where E-RPS sampled less than 20% compared with the other phases, and nicosulfuron, where HLB sampled noticeably more than both SDB-RPS phases. All three phases will work for environmental monitoring. They are very similar, but differences indicate one cannot just use literature calibration data and transfer these from one SDB phase to another, though for most compounds, it may work fine.Graphical abstract

Sorption and desorption of sex hormones in soil- and sediment-water systems: A review

Sex hormones are a group of potent endocrine disruptors that can be released into agricultural soils and sediment via wastewater discharge and manure fertilization. Sorption represents a critical determinant for the transport potential and risks of sex hormones in the environment. Therefore, this study reviewed the sorption and desorption mechanisms of sex hormones in soil- and sediment-water systems, and summarized the effects of various factors on sorption and desorption processes. A total of 359 set of sorption data were collected from the literature. Sex hormones were mostly described by the linear model. The sorption magnitudes (logKoc) of estrogens, androgens, and progestins were in the range of 2.77–3.90, 2.55–4.18, and 2.61–4.39, respectively. The average logKoc values of the sex hormones were significantly correlated with their logKow values (R2= 0.13, p < 0.05), while the R2 values were much lower than those when fewer sex hormones were included for analysis. In addition, the Kd values of most sex hormones were significantly correlated with the OC% of soils and sediment (R2= 0.16–0.99, p < 0.05), but were insignificantly correlated with the particle size distribution and surface area. These results indicated that hydrophobic partitioning interaction and other specific interactions are responsible for sex hormone uptake in soil- and sediment-water systems. The sorption of sex hormones in soil- and sediment-water systems can also be affected by other environmental variables, including pH, temperature, and ionic strength. Future studies should focus on the coupled leaching-sorption processes in manure-water-soil systems under field-scale conditions.

Adsorption of five emerging contaminants on activated carbon from aqueous medium: kinetic characteristics and computational modeling for plausible mechanism.

Pharmaceuticals and personal care products (PPCPs) do not have standard regulations for discharge in the environment and are categorized as contaminants of emerging concern as they pose potential threats to ecology as well as humans even at low concentrations. Conventional treatment processes generally employed in the wastewater treatment plants are not adequately engineered for effective removal of PPCPs. Identifying cost-effective tertiary treatment is therefore, important for complete removal of PPCPs from wastewater prior to discharge or reuse. Present study demonstrates adsorption using granular-activated carbon (GAC) as a possible tertiary treatment for simultaneous removal of five PPCPs from aqueous media. Adsorbent was characterized in terms of morphology, surface area, surface charge distribution, and presence of functional groups. Performance of GAC was investigated for sorption of three hydrophilic (ciprofloxacin, acetaminophen, and caffeine) and two hydrophobic (benzophenone and irgasan) PPCPs from aqueous solution varying the process parameters (initial concentration, adsorbent dose, pH, agitation time). Langmuir isotherm model (correlation coefficients (R2): 0.993 to 0.998) appeared to fit the isotherm data better than Temkin isotherm model for these adsorbates. Adsorption efficiencies of these compounds (8.26 to 20.40 mg g-1) were in accordance with their log Kow values. While the adsorption kinetics was best explained in terms of a pseudo-second-order kinetic model, the data suggested that adsorption mechanism was mainly governed by the intraparticle diffusion. The role of physical factors like molecular volume, molecular size, and area of targeted PPCPs were investigated through computational studies which in turn can help predicting their uptake onto GAC.

A comparative study on the adsorption behavior of pesticides by pristine and aged microplastics from agricultural polyethylene soil films

Compared with pristine agricultural polyethylene (PE) soil films microplastics (MPs), aged agricultural polyethylene (APE) soil films MPs have a rougher surface, more cracks and have some oxygen-containing functional groups that makes them adsorb organic pollutants, such as pesticides more easily. This may be more harmful to human beings than marine MPs as the agricultural soil films are closer to our living environment. But few works focused on the adsorption of pesticides on pristine or aged agricultural polyethylene soil films MPs. In order to promote the risk assessment of co-exposure of pesticides and agricultural polyethylene soil films MPs, a comparative study on the adsorption behavior and mechanism of four pesticides (carbendazim, diflubenzuron, malathion, difenoconazole) by pristine PE MPs and APE MPs were carried out in this paper. The results showed microcracks and surface oxidation observed on APE MPs. The adsorption kinetics and isotherm models indicated that the adsorption capacity of APE MPs was higher than that of PE MPs, which attribute to the larger surface area of APE MPs. The adsorption capacities of pesticides on APE MPs were positively correlated with LogKow (Water octanol partition coefficient) values of these four pesticides, showed the hydrophobic partitioning played the most important part in the adsorption, but also some H-bonding between secondary amines in the molecular of diflubenzuron and polar O-containing functional groups on APE MPs may be formed. And electrostatic forces or interactions are not the determining factor for these pesticides adsorption behavior of PE MPs, and the effect of pH is mainly driven by changes in sorbate properties rather than changes in surface properties of MPs. The results presented herein show the APE MPs can be a better vector of most hydrophobic pesticides than pristine MPs in the agricultural field, and more attention should be paid to the problem of films and pesticides residue in farmland soil.

Bioaccumulation and toxic potencies of polycyclic aromatic hydrocarbons in freshwater biota from the Ogbese River, Nigeria

Samples of fish and shellfish (periwinkles, mussel, and snail) collected from the rapidly contaminated Ogbese River, Ondo State, Nigeria, were analyzed for their polycyclic aromatic hydrocarbon (PAH) levels by gas chromatography-mass spectrometry after cleanup using solid-phase extraction. The rank order of concentration of ΣPAHs in fish follows: gills >> eggs >>> muscle. The dry weight concentrations (μg/g) of total PAHs ranged from < 0.001 to 2.06, 0.01 to 18.67, 0.01 to 9.56, and 0.01 to 8.28 in fish muscle, periwinkle, snail, and mussel respectively. Accumulation levels of PAHs in the biota were used to calculate biota-sediment (or porewater) accumulation factors (BSAF (BPwAF)) and bioaccumulation factor (BAF). The lower molecular weight PAHs constitute major components (≥ 87% in each case) of PAH congener profiles. Bioaccumulation was greatest for PAHs with log Kow values between 5.0 and 5.6. However, the study did not show a good correlation between log Kow of individual PAH and the corresponding BSAFs/BPwAF for the biota. The study indicates that significantly greater (p < 0.05) BSAFs for ΣPAHs were observed in the three bottom dwellers than in fish muscle which suggests that the sediment-feeding behavior largely affected the extent of PAH bioaccumulation in the aquatic organisms. The calculated potency equivalent concentration (PEC) of total PAHs was above the recommended screening value (SV) in US EPA guidelines, suggesting great concern for human consumption. However, estimated excess cancer risk (ECR) induced by dietary exposure only suggests potential cancer risk. The study suggests urgent remediation of the river to safeguard public health.

Assessing the role of the “estuarine filter” for emerging contaminants: pharmaceuticals, perfluoroalkyl compounds and plasticisers in sediment cores from two contrasting systems in the southern U.K.

The environmental occurrence, fate and ecotoxicity of emerging contaminants (ECs) has been the subject of increasing research, policy and public concern over the past two decades. While a wide range of publications have examined the environmental persistence and sediment/soil interactions of ECs following their discharge into aquatic environments, the extent to which ECs are sequestered in estuarine sediments, and the impact of this on their environmental persistence and supply to the ocean, in comparison remains unclear. This Article examines the environmental concentrations of seven, relatively water-soluble and environmentally mobile, ECs (including pharmaceuticals, perfluoroalkyl compounds, and plasticisers) in dated intertidal saltmarsh cores from two contrasting estuarine sites in the southern U.K. (one heavily urbanised/industrial, the other non-urbanised). Mean sediment EC concentrations are similar in both estuarine systems (in the range 0.1 (acetaminophen) to 17 (4-hydroxyacetophenone) ng/g dry weight). Despite their variable reported Log Kow values (from ca. 0.5 to > 7), the ECs are all apparently mobile in the marsh systems studied, and where subsurface concentration maxima are present these most likely relate to local flushing or diffusive processes and cannot be clearly linked to likely input trends or changes in sediment geochemistry (including sedimentary organic carbon content). The “estuarine filter” here, at least with respect to intertidal saltmarsh sediments, shows reduced potential to sequester the seven ECs examined and mediate their supply to coastal and shelf environments.

The modified IL-8 Luc assay, an in vitro skin sensitisation test, can significantly improve the false-negative judgment of lipophilic sensitizers with logKow values > 3.5.

False-negative judgment due to poor chemical solubility is a problem with in vitro skin sensitisation tests. Water-insoluble chemicals are typically dissolved in DMSO in most sensitisation tests but precipitate when diluted with medium beyond their solubility in water. Such tests lack procedures to rule out false-negative judgments due to poor solubility. The IL-8 Luc assay (OECD442E) is unique in that if chemicals do not dissolve at 20mg/mL in medium and have no effect on IL-8 luciferase activity (IL8LA), they are classified as indeterminate. The purpose of the present study was to reduce the number of indeterminate chemicals and improve assay performance. The IL-8 Luc assay can simultaneously examine glyceraldehyde 3-phosphate dehydrogenase luciferase activity (GAPLA) and IL8LA, and thus we examined the correlation between the reduction of GAPLA (defined as Inh-GAPLA) and the reduction of propidium iodide (PI)-excluding cells for three sensitizers and three non-sensitizers. We observed a significant correlation between luciferase activity driven by the GAPDH promoter of THP-G8 cells and the number of viable cells. Furthermore, chemicals providing an Inh-GAPLA value below 0.8 always reduced the ratio of PI-excluding cells to less than 0.6. Using the modified criteria, indeterminate chemicals are judged as negative if they provide Inh-GAPLA values below 0.8. This modification reduced the number of indeterminate chemicals and increased specificity, highlighting the unique advantage of the IL-8 Luc assay.

Drugs in the environment: Do we know the risks?

Abstract The occurrence of residual drugs in sewage and natural waters is an important international topic. The behavior of compounds in the environment and sewage treatment plants (ETEs) is influenced by their physicochemical properties, which govern partition in water, soil or biota. The present study aims to identify the presence of clonazepan, simvastatin, paracetamol, atenolol, carbamazepine and fluoxetine drugs in biosolid from TEE before and after the composting process. Based on the Environmental Protection Agency's Structure-Activity Relationship Model (ECOSAR) Program (EPA), and according to ZAGATTO (2006), the octanol/water partition coefficient (Kow) observed for ibuprofen drugs, fluoxetine and sinvastanin was 3.97, 3.82 and 4.68, respectively, denoting its bioaccumulation potential, which does not happen with the other compounds, as they present logKow &amp;lt; 3, being log kow = 0.03 for atenolol; 2.3 for carbamazepine; 0.49 for paracetamol and 2.53 for clorazepam. AQUINO, 2013, mentions that drugs with logKow &amp;lt; 2.5 have high hydrophylycity and low absorption trend in biomass and lipid fractions of suspended solids. For Log Kow values between 2.5 and 4.0, there is a moderate tendency of absorption in these matrices. Data on ecotoxicity, provided by the ECOSAR program, indicate the effects observed in fish, at the concentration of 30 μg/L for Sinvastatin and 20 μg/L for Fluoxetine. The agricultural use of biosolids is a controversial subject due to the potential adverse impacts on human health. In the name of safety, strict standards, high quality criteria and restrictions on use are imposed, and standards should be based on risk assessment, but there is a lack of data on the subject, and there is still no clarity as to what constitutes tolerable risk in the brazilian context for the composition of a pattern. Key messages According to the results obtained, it is verified that the studied compounds have the potential to cause deleterious effects on the evaluated organisms, according to the ECOSAR model. Considering the little information available on the subject, especially in relation to the incidence and persistence of drugs in the environment, the continuity of studies is necessary.

A simple route to suspend boric acid in non-polar media

It is a very challenging purpose to suspend a nanoparticle in a non-polar medium. In this study, stable nanofluid of nanostructured lamellar boric acid (nBA), which is highly hydrophilic compound (log Kow value is 0.18), to be suspended in non-polar media was successfully prepared. Group III base oil; i.e. mineral base oil, was used for modeling non-polar media. According to characterization examinations, optimal nBA nanofluid adding ratio is found to be 3%. Viscosity analyses were held by Brookfield DV2T® Viscometer. Friction effect of adding the nBA nanofluid into base oil was characterized by a reciprocating tribometer. Stability of nanofluid suspension in base oil was characterized by Turbiscan Tower® instrument. Viscosity of original base oil was decreased by 2.88% at 100 °C, friction coefficient value of base oil was decreased by 2.91%; Turbiscan Stability Index (TSI) values of prepared sample was 2.9. These characterizations showed that boric acid, a highly hydrophobic material, suspended in a non-polar environment with the help of a simple route containing auxiliary chemicals and ultrasonic horn.

Distributions, transports and fates of short- and medium-chain chlorinated paraffins in a typical river-estuary system

Chlorinated paraffins (CPs) are widely employed in a variety of domestic and industrial products, and are ubiquitously detected in the environment. Short-chain chlorinated paraffins (SCCPs) have been listed in the Stockholm Convention as persistent organic pollutants (POPs), but not medium-chain chlorinated paraffins (MCCPs), even though they exhibit physicochemical properties and environmental behaviors similar to SCCPs. However, very limited data are available regarding their environmental behaviors and fates in river-estuary systems. China is the major producer of chlorinated paraffins (CPs), and Shandong Province is the main producer of CPs in China. Here, we investigated the distribution, transport, and fate of SCCPs and MCCPs in a heavily polluted river in Shandong Province, aiming to explore the distributions of CPs between dissolved and particulate phases, and between water and sediment phases, as well as the transport of CPs from river headwaters to estuaries and the roles of the estuarine turbidity maximum zone (ETM) on the fate of CPs. CP concentrations in sediments were 9.1–16,000 ng/g dw (mean value: 1000 ng/g dw) for SCCPs and 2.4–27,000 ng/g dw (mean value: 4400 ng/g dw) for MCCPs. In the water column, CP concentrations were 7.4–470 ng/L for SCCPs (mean value: 43 ng/L) and 4.0–120 ng/L for MCCPs (mean value: 27 ng/L). CP concentrations in riverine sediments were among the highest worldwide. SCCPs accounted for 95% of CPs (sum of SCCPs and MCCPs) in the dissolved phase. Cities around the river basin were found to be important pollution sources for CPs. Long-chained and more chlorinated congeners with larger LogKow values might be more likely to be ‘salted-out’, and thus, will be sequestrated in sediments in the ETM, while those lighter congener groups with relatively high water solubility were prone to be transported by water flow to larger distances.

Fractionated stir bar sorptive extraction using conventional and solvent-assisted approaches for enhanced identification capabilities of aroma compounds in beverages.

For successful profiling of aroma carriers in food samples, a highly efficient extraction method is mandatory. A two-step stir bar sorptive extraction (SBSE) approach, namely fractionated SBSE (Fr-SBSE), was developed to improve both the organoleptic and the chemical identification of aroma compounds in beverages. Fr-SBSE consists of two multi-SBSE procedures (mSBSE) performed sequentially on the same sample. The first extraction consists of a conventional mSBSE using three polydimethylsiloxane (PDMS) stir bars (1stmSBSE). This is followed by a solvent-assisted mSBSE performed on the same sample using three solvent-swollen PDMS stir bars (2nd SA-mSBSE). The 1stmSBSE mainly extracts apolar/medium polar solutes with log Kow values >2, while the 2nd SA-mSBSE mainly extracts polar solutes with log Kow values <2. After this two-step fractionation procedure, either thermal desorption (TD) or liquid desorption - large volume injection (LD-LVI), followed by GC-MS is performed on each set of three stir bars. A real-life sample of roasted green tea was used for method development. The performance of the Fr-SBSE method is further illustrated with sensory evaluations and GC-MS analysis for a stout beer sample. Compared to an extraction procedure with SA-mSBSE only, Fr-SBSE including a 1stmSBSE and a 2nd SA-mSBSE reduced co-elution of aroma compounds in the chromatograms and was capable of providing improved mass spectral quality for identification of 17 additional compounds in roasted green tea, and 12 additional compounds in stout beer, respectively. Moreover, odor description and characterization were clearly improved.

Tissue distribution and bioaccumulation of organophosphate esters in wild marine fish from Laizhou Bay, North China: Implications of human exposure via fish consumption

Despite organophosphate esters (OPEs) are ubiquitous in the environment, limited information is available about their tissue-specific accumulation potential in marine fish and exposure risks. Ten fish species from the coastal area of Laizhou Bay, North China, were sampled and analyzed to investigate tissue levels, bioaccumulation, and human exposure risks of 20 OPEs. Seventeen OPEs were detected in fish tissues with total concentration ranging from 6.6–107 ng/g dry weight. The average log bioaccumulation factor (BAF) values of OPEs ranged from 2.8 to 4.4 in livers, 2.3–3.8 in muscles, 2.5–3.9 in gills, and 2.8–4.4 in kidneys. The log BAF values of OPEs significantly increased with increasing their log KOW values (r = 0.55–0.63, p < 0.001). The estimated daily intake of OPEs ranged from 1.7–12.0 and 3.1–22.1 ng/kg bw/d for rural and urban residents, respectively. The hazard quotients of OPEs were in the range of 4 × 10 −5 to 6.7 × 10 −4 and 7 × 10 −5 to 1.2 × 10 −3 for rural and urban residents, respectively. Results showed that the human health risks of OPEs associated with fish consumption is at low level.