scholarly journals Adsorption and Desorption Behaviour of Polychlorinated Biphenyls onto Microplastics’ Surfaces in Water/Sediment Systems

Toxics ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 59
Author(s):  
Marta Llorca ◽  
Manuela Ábalos ◽  
Albert Vega-Herrera ◽  
Miquel A. Adrados ◽  
Esteban Abad ◽  
...  
Keyword(s):  
Polychlorinated Biphenyls ◽  
Polyethylene Terephthalate ◽  
Food Chain ◽  
Environmental Conditions ◽  
Freundlich Isotherm ◽  
Water Systems ◽  
Lower Degree ◽  
Π Interactions ◽  
Adsorption Desorption ◽  
High Degree

The potential of microplastics (MPLs) in marine ecosystems to adsorb and transport other micropollutants to biota, contributing to their entry in the food chain, is a primary cause of concern. However, these interactions remain poorly understood. Here, we have evaluated the adsorption/desorption behaviour of marker polychlorinated biphenyls (PCBs), onto MPL surfaces of three widely used polymers—polystyrene (PS), polyethylene (PE), and polyethylene terephthalate (PET). The range of MPL sizes ranged from 1 to 600 μm. The adsorption/desorption was evaluated in sediment/water systems in marine microcosms emulating realistic environmental conditions for 21 days. The adsorption percentages ranged from 20 to 60%. PCBs with a lower degree of chlorination showed higher adsorption percentages because of conformational impediments of PCBs with high-degree chlorination, and also by their affinity to be adsorbed in sediments. Glassy plastic polymers as PET and PS showed a superior affinity for PCBs than rubbery polymers, such as PE. The polymers that can bond PCBs by π-π interactions, rather than van der Waals forces showed better adsorption percentages, as expected. Finally, the adsorption/desorption behaviour of selected PCBs onto MPLs was fitted to a Freundlich isotherm model, with correlations higher than 0.8 in most of the cases.

Bioaccumulation of Polychlorinated Biphenyls and Organochlorine Pesticides in Selected Fish Species as an Indicator of the Pollution of Aquatic Resources in Vojvodina, Yugoslavia

1992 ◽  
Vol 26 (9-11) ◽  
pp. 2361-2364 ◽  
Author(s):  
M. Vojinovic-Miloradov ◽  
P. Marjanovic ◽  
D. Buzarov ◽  
S. Pavkov ◽  
Lj. Dimitrijevic ◽  
...  
Keyword(s):  
Polychlorinated Biphenyls ◽  
Organochlorine Pesticides ◽  
Fish Species ◽  
Food Chain ◽  
Limit Of Detection ◽  
Fish Tissue ◽  
Aquatic Resources ◽  
Fish Samples ◽  
High Concentrations ◽  
High Degree

Long term pollution of selected aquatic resources of Vojvodina with polychlorinated biphenyls (PCB's) and organochlorine pesticides (OCP's) has led to high degree of bioaccumulation of the above chemicals along the food chain. This paper documents the bioaccumulation in two fish species commonly found in rivers and canals of Vojvodina, common carp (Cyprinus Carpio) and pike (Exos lucinus). Samples offish, sediment and water were collected from the Danube, Sava and Tisa rivers and a fish farm “Ečka” which is supplied with water from the river Tisa and river Begej. All samples were analysed by highly sensitive capillary column GC using EC detectors. Samples were analysedfor aspectrum of compounds and are presented here as total PCB's and OCP's. The results show that the studied compounds are present in water samples at very low concentrations (PCB's in concentrations at or below the limit of detection, OCP's in concentrations below the legally allowable concentrations by Yugoslav norms). The sediment samples contain the studied compounds at significantly higher concentrations but still within the expectable range. Fish tissue contained elevated concentrations, and especially so the tissue of the top predator in the food chain, the Pike, showing that bioaccumulation has occurred. Of special concern are the extremely high concentrations of PCB's in the tissue of fish samples collected from river Sava indicating the still existing effects of pollution by PCB's in the watershed of the river Sava.

scholarly journals Adsorption, desorption and fractionation of As(V) on untreated and mussel shell-treated granitic material

Solid Earth ◽  
2015 ◽  
Vol 6 (1) ◽  
pp. 337-346 ◽  
Author(s):  
N. Seco-Reigosa ◽  
L. Cutillas-Barreiro ◽  
J. C. Nóvoa-Muñoz ◽  
M. Arias-Estévez ◽  
E. Álvarez-Rodríguez ◽  
...  
Keyword(s):  
Food Chain ◽  
Soluble Fraction ◽  
Mussel Shell ◽  
Weakly Bound ◽  
Retention Capacity ◽  
Adsorption Data ◽  
Water Courses ◽  
Ph Range ◽  
Adsorption Desorption ◽  
Langmuir And Freundlich Models

Abstract. As(V) adsorption and desorption were studied on granitic material, coarse and fine mussel shell and granitic material amended with 12 and 24 t ha−1 fine shell, investigating the effect of different As(V) concentrations and different pH as well as the fractions where the adsorbed As(V) was retained. As(V) adsorption was higher on fine than on coarse shell. Mussel shell amendment increased As(V) adsorption on granitic material. Adsorption data corresponding to the unamended and shell-amended granitic material were satisfactory fitted to the Langmuir and Freundlich models. Desorption was always <19% when the highest As(V) concentration (100 mg L−1) was added. Regarding the effect of pH, the granitic material showed its highest adsorption (66%) at pH <6, and it was lower as pH increased. Fine shell presented notable adsorption in the whole pH range between 6 and 12, with a maximum of 83%. The shell-amended granitic material showed high As(V) adsorption, with a maximum (99%) at pH near 8, but decreased as pH increased. Desorption varying pH was always <26%. In the granitic material, desorption increased progressively when pH increased from 4 to 6, contrary to what happened to mussel shell. Regarding the fractionation of the adsorbed As(V), most of it was in the soluble fraction (weakly bound). The granitic material did not show high As(V) retention capacity, which could facilitate As(V) transfer to water courses and to the food chain in case of As(V) compounds being applied on this material; however, the mussel shell amendment increased As(V) retention, making this practice recommendable.

Stimulus-Change Effects of Forcing in Alternation Behavior

1966 ◽  
Vol 19 (2) ◽  
pp. 515-518 ◽  
Author(s):  
R. N. Hughes
Keyword(s):  
Free Choice ◽  
Stimulus Change ◽  
Lower Degree ◽  
Alternation Behavior ◽  
Subsequent Removal ◽  
Transparent Barrier ◽  
Initial Attraction ◽  
High Degree

To test the hypothesis that forcing left or right in a T-maze produces more alternation because of the stimulus-change resulting from subsequent removal of the arm barrier, rats were given free-choice trials and forced trials with a wooden barrier (favouring a high degree of change) and with a transparent barrier (favouring a lower degree of change). Although alternation was unaffected by the three conditions, the percentage of first investigatory responses directed toward the alternate arm on Trial 2 was highest following forcing with the wooden barrier. It was concluded that a stimulus-change explanation for the effects of forcing was acceptable if these first investigatory responses were acknowledged as indices of initial attraction of attention by an arm.

Foreign Employment, Income Shifting, and Tax Uncertainty

2021 ◽  
Author(s):  
Katharine D. Drake ◽  
Nathan C. Goldman ◽  
Frank Murphy
Keyword(s):  
Supply Chain ◽  
Selection Bias ◽  
Lower Degree ◽  
Income Shifting ◽  
Costs And Benefits ◽  
High Degree ◽  
The U.S ◽  
Tax Uncertainty

We examine the effect of foreign employment on two outcomes-income shifting and the tax uncertainty of foreign transactions. Using a hand-collected sample of employment disclosures, we partition our sample into firm-years with a higher or lower degree of foreign employment. Using two distinct income shifting models, we document that, on average, a high degree of foreign employment is associated with greater tax-motivated income shifting out of the U.S. We also posit and find that a high degree of foreign employment enhances the economic substance of foreign transactions, reducing the tax uncertainty associated with foreign income. We conduct additional analyses to mitigate selection bias concerns, and we use exogenous changes to the costs and benefits of income shifting using foreign employment to strengthen identification. Our results highlight firms' use of employees as part of a tax-efficient supply chain and how foreign employment enhances income shifting opportunities between jurisdictions.

scholarly journals An Environmental Friendly Perspective of Microbial Degradation

2018 ◽  
Vol 3 (2) ◽  
Keyword(s):  
Heavy Metals ◽  
Polychlorinated Biphenyls ◽  
Microbial Degradation ◽  
Aromatic Hydrocarbons ◽  
Environmental Conditions ◽  
Cost Effective ◽  
Environmental Friendly ◽  
Naturally Occurring ◽  
Degradation Of Pollutants ◽  
Poly Aromatic Hydrocarbons

In the recent years attempt to find cost-effective and ecological ways to deal with noxious waste led mankind to focus on the use of microbes for the degradation of pollutants. These environmental friendly remediation methods employs the microbial naturally occurring catabolic capabilities to alter, vitiate or accrue a large number of pollutants including poly aromatic hydrocarbons, polychlorinated biphenyls, radio nuclides ,heavy metals etc. High-through put analyses of environmentally relevant microbes provides an insight of their major degradative pathways as well as their competence to acclimate to altering environmental conditions.

scholarly journals Efficient Separation of Heavy Metals by Magnetic Nanostructured Beads

Inorganics ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 40 ◽  
Author(s):  
Lisandra de Castro Alves ◽  
Susana Yáñez-Vilar ◽  
Yolanda Piñeiro-Redondo ◽  
José Rivas
Keyword(s):  
Heavy Metals ◽  
Ternary System ◽  
Metal Ions ◽  
Adsorption Capacity ◽  
Freundlich Isotherm ◽  
Metal System ◽  
Adsorption Sites ◽  
Removal Of Heavy Metals ◽  
Adsorption Desorption ◽  
Efficient Adsorbent

This study reports the ability of magnetic alginate activated carbon (MAAC) beads to remove Cd(II), Hg(II), and Ni(II) from water in a mono-metal and ternary system. The adsorption capacity of the MAAC beads was highest in the mono-metal system. The removal efficiency of such metal ions falls in the range of 20–80% and it followed the order Cd(II) > Ni(II) > Hg(II). The model that best fitted in the ternary system was the Freundlich isotherm, while in the mono-system it was the Langmuir isotherm. The maximum Cd(II), Hg(II), and Ni(II) adsorption capacities calculated from the Freundlich isotherm in the mono-metal system were 7.09, 5.08, and 4.82 (mg/g) (mg/L)1/n, respectively. Lower adsorption capacity was observed in the ternary system due to the competition of metal ions for available adsorption sites. Desorption and reusability experiments demonstrated the MAAC beads could be used for at least five consecutive adsorption/desorption cycles. These findings suggest the practical use of the MAAC beads as efficient adsorbent for the removal of heavy metals from wastewater.

scholarly journals Adsorption of As(V) from Aqueous Solution on Chitosan-Modified Diatomite

2020 ◽  
Vol 17 (2) ◽  
pp. 429 ◽  
Author(s):  
Qintao Yang ◽  
Liang Gong ◽  
Lili Huang ◽  
Qinglin Xie ◽  
Yijian Zhong ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Removal Efficiency ◽  
Ph Effect ◽  
Freundlich Isotherm ◽  
Xrd Analysis ◽  
Optimal Value ◽  
Equilibrium Data ◽  
Pseudo Second Order ◽  
Adsorption Desorption ◽  
Modified Diatomite

A novel chitosan (CS)-modified diatomite (Dt) was prepared by a simple mixture in the mass ratio to remove As(V) from aqueous solution in this research. The CS-modified Dt adsorbent was characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray powder diffraction (XRD) analysis. The parameters to influence the adsorption of As(V) ion were studied under such conditions as kinetics, adsorption isotherm, and pH effect. The results revealed that adsorption of As(V) was initially rapid and the equilibrium time was reached after 40 min. The optimal value of the pH was 5.0 for better adsorption. The equilibrium data were well fitted to the Langmuir isotherm compared to the Freundlich isotherm, and exhibited the highest capacity and removal efficiency of 94.3% under an initial As(V) concentration of 5 mg/L. The kinetic data were well described by the pseudo-second-order model. In addition, 0.1 M NaOH has the best desorption efficiency of As(V) adsorbed on CS-modified Dt, and the removal efficiency of As(V) was still higher than 90% when after six adsorption-desorption cycles. These results showed that the CS-modified Dt could be considered as a potential adsorbent for the removal of As(V) in aqueous solution.

INVESTIGATION OF POLYCHLORINATED BIPHENYLS (PCBs) REMOVAL BY SIGNAL WALLED CARBON NANOTUBES: STUDIES

2011 ◽  
Vol 10 (05) ◽  
pp. 651-657 ◽  
Author(s):  
LEILA MAHDAVIAN
Keyword(s):  
Carbon Nanotubes ◽  
Thermodynamic Properties ◽  
Potential Energy ◽  
Polychlorinated Biphenyls ◽  
Food Chain ◽  
Environment Protection ◽  
Dft Methods ◽  
Single Walled Nanotubes ◽  
Chemical Pollutants ◽  
Walled Carbon Nanotubes

Polychlorinated biphenyls (PCBs) are highly toxic and widespread pollutants due in part to their resistance to biodegradation. In water, their breakdown and analysis are low, but are readily adsorbed by fish and microscopic organisms, and these substances accumulate in the food chain and end up in human bodies when people consume sea food. The elimination of chemical pollutants from a contaminated environment is one of the most important steps toward achieving the goal of environment protection. Using single-walled nanotubes (SWNTs) has shown the efficiency to remove PCBs from air and water. There are four situations for PCBs and SWNTs (6, 6) that we have investigated passing them between nanotubes. The thermodynamic properties are calculated for passing PCBs between them by DFT methods. This passing has a low potential energy in the middle of nanotubes, as the thermodynamic properties show; this passing is spontaneous and favorable because ΔG ele (MJ/mol) is negative for them.

scholarly journals Contamination of the food chain by polychlorinated biphenyls from a broken transformer.

1983 ◽  
Vol 73 (3) ◽  
pp. 290-292 ◽  
Author(s):  
D P Drotman ◽  
P J Baxter ◽  
J A Liddle ◽  
C D Brokopp ◽  
M D Skinner
Keyword(s):  
Polychlorinated Biphenyls ◽  
Food Chain

Polychlorinated Biphenyls in Food: A Review

1985 ◽  
Vol 48 (5) ◽  
pp. 442-448 ◽  
Author(s):  
BRIJ L. SAWHNEY ◽  
LESTER HANKIN
Keyword(s):  
Polychlorinated Biphenyls ◽  
Human Milk ◽  
Food Chain ◽  
Dairy Products ◽  
Polychlorinated Biphenyl ◽  
Packaging Materials ◽  
Processed Food ◽  
High Concentrations ◽  
Electrical Transformers

Literature published from 1970 through mid-1984 on polychlorinated biphenyl (PCB) contamination of foods, including fish, dairy products, packaged and processed food and human milk, is reviewed. Sources of the contamination are discussed. The reports show that although PCBs are no longer manufactured in this country, large quantities have entered the environment. High concentrations in sediments of some streams and lakes are a continuing source of PCB entry into the food chain via the fish caught in these waters. Accidental leakage and spills from electrical transformers containing PCBs, which are in use, can also be a source of contamination. Other sources of PCB contamination such as silo sealants and packaging materials manufactured from carbonless paper containing PCBs have been essentially eliminated.

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