Phthalate ester levels in agricultural soils of greenhouses, their potential sources, the role of plastic cover material, and dietary exposure calculated from modeled concentrations in tomato

Soil samples collected from 50 greenhouses (GHs) cultivated with tomatoes (plastic-covered:24, glass-covered:26), 5 open-area tomato growing farmlands, and 5 non-agricultural areas were analyzed in summer and winter seasons for 13 PAEs. The total concentrations (Σ13PAEs) in the GHs ranged from 212 to 2484 ng/g, wheeas the concentrations in open-area farm soils were between 240 and 1248 ng/g. Σ13PAE in non-agricultural areas was lower (35.0 - 585 ng/g). PAE exposure through the ingestion of tomatoes cultivated in GH soils and associated risks were estimated with Monte Carlo simulations after calculating the PAE concentrations in tomatoes using a partition-limited model. DEHP was estimated to have the highest concentrations in the tomatoes grown in both types of GHs. The mean carcinogenic risk caused by DEHP for tomato grown in plastic-covered GHs, glass-covered GHs, and open-area soils were 2.4 × 10-5, 1.7 × 10-5 and 1.1 × 10-5, respectively. Based on Positive Matrix Factorization results, plastic material usage in GHs (including plastic cover material source for plastic-GHs) was found to be the highest contributing source in both types of GHs. Microplastic analysis indicated that the ropes and irrigation pipes inside the GHs are important sources of PAE pollution. Pesticide application is the second highest contributing source.

Combined approaches for detecting polypropylene microplastics in crop plants

Microplastics (MPs) pollution in the terrestrial environment causes accumulation in crop plants. Consumption of these plants may have negative effects on human health. Therefore, it is crucial to analyze MPs accumulation in the plants. The aim of this study is to determine polypropylene (PP) particles in plants exposed to label-free PP for 75 days. In order to extract PP from organic matter, a two-step alkaline and wet peroxide oxidation chemical digestion method was applied to the roots, stems, and leaves of maize and wheat. The PP particles in the digested solutions were detected by the Nile red staining method, which has not been used previously in the detection of MPs in plants. Nile red stained PP particles mostly accumulated in the roots of wheat and the stems of maize plants. Statistical analysis revealed that the maize deposited more and larger PP particles regardless of the location. Moreover, the presence of PP particles in the digestion solutions was proved by the heating method. The PP particles on the glass slides were transformed into different shapes due to melting.

Evaluation of levels and sources of microplastics and phthalic acid esters and their relationships in the atmosphere of highly industrialized and urbanized Gebze, Türkiye

The presence of microplastics (MPs) in the atmosphere and their relationship with other pollutants have been gaining attention due to both their ubiquity and threatening human health. As well phthalic acid esters (PAEs) regarding as plasticizers for being added in plastic materials are key role for plastic pollution. In this study, the concentrations and sources of airborne MPs together with major PAEs and their relationships were investigated for four seasons. MP particles <20 μm, constituting the majority of the samples, were successfully revealed by NR fluorescent analysis. As a result of the μATR-FTIR analyzes, it was seen that besides different polymer derivatives, dye-pigment types, some minerals and compounds, and abundant semi-synthetic fibers and natural fibers were also present. MPs concentration were found in the range of 7207-21,042 MP/m³ in summer, 7245-32,950 MP/m³ in autumn, 4035-58,270 MP/m³ in winter and 7275-37,094 MP/m³ in spring. For the same period, the concentrations of PAEs ranged from 9.24 to 115.21 ng/m³ with an average value of 38.08 ± 7.92 ng/m³. PMF was also applied and four factors were extracted. Factor 1, accounts 52.26 % and 23.27 % of the total PAEs and MPs variances, was attributed to PVC sources. Factor 2, explaining 64.98 % of the total MPs variance had the highest loading of MPs and moderate loadings of relatively low molecular weight of PAEs, was attributed to plastics and personal care products. Factor 3, explaining the 28.31 % of the total PAEs variance was laden with BBP, DnBP, DiBP and DEP and was attributed to various plastic input during the sampling campaign coming from the industrial activities. The last factor accounts for 11.65 % of the total PAEs variance and was dominated by DMEP and it was linked to a source of the activities performed in the laboratories of the university.

Tiny, shiny, and colorful microplastics: Are regular glitters a significant source of microplastics?

Used in significant volumes in make-up, craft activities, and -more recently- in textile products, glitters are among single-use plastics, and are often made of polyethylene terephthalate. Even though a wealth of studies focus on the sources of microplastics in the environment and biota, glitters produced in various countries, and used extensively in entertainment events, shows and carnivals around the globe, not to mention by virtually anyone in daily life settings, have been relatively ignored as a major source of microplastics. That is why the present study focuses specifically on plastic glitters, and attempts to track them in the environment, in a manner comparable to their use in forensic science where glitters are often used as trace evidence associating a suspect with a specific murder case. Doing so led to various pieces of evidence of the presence of glitters -arguably a stealthy source of microplastics - in samples taken from the environment at a wide range of locations around the world.

Use of a convolutional neural network for the classification of microbeads in urban wastewater

Scientists are on the lookout for a practical model that can serve as a standard for sorting out, identifying, and characterizing microplastics which are common occurrences in water sources and wastewaters. The microbeads (MBs) used in cosmetics and discharged into the sewer systems after use cause substantial microplastics pollution in the receiving waters. Today, the use of plastic microbeads in cosmetics is banned. The existing use cases are to be discontinued within a few years. Yet, there are no restrictions regarding the use of microbeads in a number of industries, cleaning products, pharmaceuticals and medical practices. In this context, the determination and classification of MBs which had so far been discharged to water sources and which continue to be discharged, represent crucial problems. In this work, we examined a new approach for the classification of MBs based on microscopic images. For classification purposes, Convolutional Neural Network (CNN) -a Deep Learning algorithm- was employed, whereas GoogLeNet architecture served as the model. The network is built from scratch, and trained then after tested on a total of 42928 images containing MBs in 5 distinct cleansers. The study performed with the CNN which achieved a classification performance of 89% for MBs in wastewater.

Bentonite for ciprofloxacin removal from aqueous solution

Ciprofloxacin hydrochloride (CIP) is the second generation of fluoroquinolone antibiotics whose residues are found in wastewater and surface water. CIP has high aqueous solubility under different pH conditions and high stability in the soil system. In this study, bentonite was used as a potential sorbent for the removal of CIP from aqueous solutions using batch experiments. The effects of various parameters such as contact time, pH, adsorbent dosage, agitation speed, ionic strength and initial concentration of CIP in aqueous solution on the adsorption capacity were investigated. The optimum contact time, pH, agitation speed and adsorbent dosage were found to be 30 min, 4.5 pH, 150 rpm and 2.5 g L(-1), respectively. When the ionic strength was increased from 5 to 50 mM, the adsorption of CIP decreased from 97.8 to 93.4%. The isotherm adsorption data fitted well with the Langmuir model, Kl and qe were found to be 0.27 L mg(-1) and 147.06 mg g(-1), and the data fitted well with the pseudo-second order kinetics, whereby k was found to be 2.19 g mg(-1) h(-1).

Biosorption of Pb(II) ions by modified quebracho tannin resin

In this study, the effect of temperature, pH and initial metal concentration on Pb(II) biosorption on modified quebracho tannin resin (QTR) was investigated. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to investigate QTR structure and morphology. Besides, the specific BET surface area and zeta-potential of the QTR were analysed. Thermodynamic functions, the change of free energy (DeltaG degrees), enthalpy (DeltaH degrees) and entropy (DeltaS degrees) of Pb adsorption on modified tannin resin were calculated as -5.43 kJ mol(-1) (at 296+/-2K), 31.84 kJ mol(-1) and 0.127 J mmol(-1) K(-1), respectively, indicating the spontaneous, endothermic and the increased randomness nature of Pb(2+) adsorption. The kinetic data was tested using pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion model. The results suggested that the pseudo-second-order model (R(2)>0.999) was the best choice among all the kinetic models to describe the adsorption behavior of Pb(II) onto QTR. Langmuir, Freundlich and Tempkin adsorption models were used to represent the equilibrium data. The best interpretation for the experimental data was given by the Langmuir isotherm and the maximum adsorption capacity (86.207 mg g(-1)) of Pb(II) was obtained at pH 5 and 296 K.

Bosonic helium droplets with cationic impurities: onset of electrostriction and snowball effects from quantum calculations

Variational Monte Carlo and diffusion Monte Carlo calculations have been carried out for cations such as Li(+), Na(+), and K(+) as dopants of small helium clusters over a range of cluster sizes up to about 12 solvent atoms. The interaction has been modeled through a sum-of-potential picture that disregards higher order effects beyond atom-atom and atom-ion contributions. The latter were obtained from highly correlated ab initio calculations over a broad range of interatomic distances. This study focuses on two of the most striking features of the microsolvation in a quantum solvent of a cationic dopant: electrostriction and snowball effects. They are discussed here in detail and in relation with the nanoscopic properties of the interaction forces at play within a fully quantum picture of the cluster features.

Ionic dimers in He droplets: Interaction potentials for Li2+–He,Na2+–He, and K2+–He and stability of the smaller clusters

We present post Hartree-Fock calculations of the potential energy surfaces (PESs) for the ground electronic states of the three alkali dimer ions Li(2) (+),Na(2) (+), and K(2) (+) interacting with neutral helium. The calculations were carried out for the frozen molecular equilibrium geometries and for an extensive range of the remaining two Jacobi coordinates, R and theta, for which a total of about 1000 points is generated for each surface. The corresponding raw data were then fitted numerically to produce analytic expressions for the three PESs, which were in turn employed to evaluate the bound states of the three trimers for their J=0 configurations: The final spatial features of such bound states are also discussed in detail. The possible behavior of additional systems with more helium atoms surrounding the ionic dopants is gleaned from further calculations on the structural stability of aggregates with up to six He atoms. The validity of a sum-of-potential approximation to yield realistic total energies of the smaller cluster is briefly discussed vis-a-vis the results from many-body calculations.

Ab initio quantum dynamics with very weak van der Waals interactions: Structure and stability of small Li2(1Sigmag+)-(He)n clusters

The potential energy surface (PES) for the interaction between Li2(1Sigmag+) and 4He has been computed using an accurate, post-Hartree-Fock quantum calculation for its ground electronic state. The orientational anisotropy of the forces and the interplay between repulsive and attractive effects within the PES are analyzed to extract information on the possible existence of bound states in the triatomic system. The structures of a few of the Li2(He)n small clusters are examined by comparing a classical approach with a full quantum one to generate bound configurations and to extract information on the possible spatial arrangements of the smaller clusters via à vis the location of the Li2 dopant. Some significant consequences on the Li2 behavior in larger clusters and droplets are drawn from the above findings.