An overview of UV-absorbing compounds (organic UV filters) in aquatic biota

The purpose of this article is to summarize biological monitoring information on UV-absorbing compounds, commonly referred as organic UV filters or sunscreen agents, in aquatic ecosystems. To date a limited range of species (macroinvertebrates, fish, and birds), habitats (lakes, rivers, and sea), and compounds (benzophenones and camphors) have been investigated. As a consequence there is not enough data enabling reliable understanding of the global distribution and effect of UV filters on ecosystems. Both liquid chromatography and gas chromatography coupled with mass spectrometry-based methods have been developed and applied to the trace analysis of these pollutants in biota, enabling the required selectivity and sensitivity. As expected, the most lipophilic compounds occur most frequently with concentrations up to 7112?ng?g^?1 lipids in mussels and 3100?ng?g^?1 lipids (homosalate) in fish. High concentrations have also been reported for 4-methylbenzilidenecamphor (up to 1800?ng?g^?1 lipids) and octocrylene (2400?ng?g^?1 lipids). Many fewer studies have evaluated the potential bioaccumulation and biomagnification of these compounds in both fresh and marine water and terrestrial food webs. Estimated biomagnification factors suggest biomagnification in predator–prey pairs, for example bird–fish and fish–invertebrates. Ecotoxicological data and preliminary environmental assessment of the risk of UV filters are also included and discussed.     

Dechlorane Plus in eggs of two gull species (Larus michahellis and Larus audouinii) from the southwestern Mediterranean Sea

Dechlorane Plus (DP) and some of its possible degradation products were measured in eggs from the yellow-legged gull (Larus michahellis) and Audouin's gull (Larus audouinii) from a protected area in the southwestern Mediterranean Sea. Statistically significant differences were found between both gull species, with yellow-legged gull eggs showing the highest average total DP concentration (209?pg/g wet weight). According to stable nitrogen and carbon isotope values, variations in DP concentrations in the gull species studied are explained by foraging behavior and diet rather than by the trophic position. Both DP stereoisomers were quantified in all the samples studied, and a slight enrichment of the anti-DP could have occurred in both species. The quantification of anti-[DP-1Cl] only in ～58?% of yellow-legged gulls support the hypothesis of a species-dependent factor influencing the bioaccumulation and/or biotransformation of Dechlorane-related compounds. This study reports on the first measurements of Dechlorane-related compounds in biota from the North African continent, contributing to the knowledge about DP environmental fate and distribution. In the light of our results, more research on differences in species-dependent bioaccumulation and biotransformation capabilities as well as ecological effects is encouraged in future Dechlorane-related compound studies.     

Organic UV filters in marine environments: An update of analytical methodologies,occurrence and distribution

Ultraviolet filters (UV Filters) are compounds that are widely employed in personal care products such as sunscreens to protect the skin from sun damage, but they are also added to other products, such as food packaging, plastics, paints, textiles, detergents, etc. The continuous use of these products causes the release of a substantial amount of these products into the marine environment through direct input or wastewater discharge, and thus they are becoming an important class of contaminants of emerging concern. A correlation between their occurrence and different negative effects on marine biota has been reported.Taking into account all the possible impacts on the environment, knowledge of their presence and distribution in the different compartments of the ecosystems, ranging from waters and sediments to aquatic organisms, which potentially suffer from bioaccumulation and biomagnification processes, is essential. High concentrations of ultraviolet filters have been found in samples collected from across the entire planet, even in polar regions, revealing their global distribution.Therefore, interest in the sensitive determination of ultraviolet filters in several marine matrices has increased. In this article, an overall review of the more recently reported analytical chemistry methods for identifying and quantifying these compounds in marine environmental samples is presented. We compare and discuss the potential advantages and disadvantages of every step involved in the analytical procedure, including the pre-treatment, treatment and extraction processes that are required to avoid matrix effects. Moreover, we describe the worldwide occurrence and distribution of those most important UV filters.     

Analysis of polychlorinated n-alkanes in environmental samples

Polychlorinated n-alkanes (PCAs), also known as chlorinated paraffins (CPs), are highly complex technical mixtures that contain a huge number of structural isomers, theoretically more than 10,000 diastereomers and enantiomers. As a consequence of their persistence, tendency to bioaccumulation, and widespread and unrestricted use, PCAs have been found in aquatic and terrestrial food webs, even in rural and remote areas. Recently, these compounds have been included in regulatory programs of several international organizations, including the US Environmental Protection Agency and the European Union. Consequently, there is a growing demand for reliable methods with which to analyze PCAs in environmental samples. Here, we review current trends and recent developments in the analysis of PCAs in environmental samples such as air, water, sediment, and biota. Practical aspects of sample preparation, chromatographic separation, and detection are covered, with special emphasis placed on analysis of PCAs using gas chromatography–mass spectrometry. The advantages and limitations of these techniques as well as recent improvements in quantification procedures are discussed.     

Pharmaceuticals in biota in the aquatic environment: analytical methods and environmental implications

The presence of pharmaceuticals in the aquatic environment is an ever-increasing issue of concern as they are specifically designed to target specific metabolic and molecular pathways in organisms, and they may have the potential for unintended effects on nontarget species. Information on the presence of pharmaceuticals in biota is still scarce, but the scientific literature on the subject has established the possibility of bioaccumulation in exposed aquatic organisms through other environmental compartments. However, few studies have correlated both bioaccumulation of pharmaceutical compounds and the consequent effects. Analytical methodology to detect pharmaceuticals at trace quantities in biota has advanced significantly in the last few years. Nonetheless, there are still unresolved analytical challenges associated with the complexity of biological matrices, which require exhaustive extraction and purification steps, and highly sensitive and selective detection techniques. This review presents the trends in the analysis of pharmaceuticals in aquatic organisms in the last decade, recent data about the occurrence of these compounds in natural biota, and the environmental implications that chronic exposure could have on aquatic wildlife.     

Sources and Accumulation of Butyltin Compounds in Ganges River Dolphin,Platanista gangetica

Concentrations of butyltin compounds (mono-, di-, and tri-butyltin) were determined in dolphin ( Platanista gangetica ), fish, invertebrates and sediment collected from the River Ganges, India, in order to understand the contamination levels, sources, and potential for biomagnification in freshwater food chains. Total butyltin concentration in dolphin tissues was up to 2000 ng g⁻¹ wet wt, which was about 5–10 times higher than in their diet. The concentrations in fish and benthic invertebrates, including polychaetes, were 3–10 times greater than in sediment. The biomagnification factor for butyltins in river dolphin from its food was in the range 0.2–7.5. Butyltin concentrations in Ganges river organisms were higher than those reported for several persistent organochlorine compounds. Discharge of untreated domestic sewage was one of the major sources of butyltin residues in Ganges river biota. High concentrations of butyltin compounds in freshwater food chains suggest the need to assess their toxic effects in aquatic organisms and to regulate their use. © 1997 by John Wiley & Sons, Ltd.     

Liquid chromatography methodologies for the determination of steroid hormones in aquatic environmental systems

Steroid hormones are a diverse group of natural and synthetic compounds. Their wide use in human and veterinary medicine results in their continual introduction into the environment. In recent years, environmental concern over steroids that act as endocrine disruptors has increased because of their adverse effects on organisms or their progeny. Moreover, as these compounds are not totally removed from sewage in wastewater treatment plants, they can reach the aquatic environment and persist due to their physicochemical characteristics.For this reason, a major trend in analytical chemistry is the development of rapid and efficient procedures for the extraction, determination and quantification of steroid hormones in environmental samples. Over the past few decades, the significant expansion of liquid chromatography technology utilizing mass spectrometry detection has led to applications with increased selectivity and sensitivity. Optimized extraction and microextraction techniques combined to these liquid chromatography techniques have lowered detection and quantification limits to the ng L⁻¹–μg L⁻¹ range, which is the concentration of steroid hormones in liquid, solid and biota samples.In this paper, the state-of-the-art techniques for the analysis of steroid hormones focused mainly in based liquid chromatography methods in liquid and aquatic solid and biota samples are reviewed. Handling, storage, extraction and detection methodologies are reviewed and compared for all families of steroid hormones.     

Analysis of emerging and related pollutants in aquatic biota

Water bodies cover approximately 70 % of the earth´s surface, making them ecosystems with a high environmental value and the habitat for numerous species of flora and fauna. Emerging pollutants (EPs) are ubiquitous anthropogenic compounds of environmental concern that can be found at different concentration levels in matrices such as sediment, water and aquatic biota. In addition, EPs can be bioaccumulated and biomagnified, inducing adverse effects on biota, and posing a risk to humans when contaminated biota is consumed. Unlike abiotic matrices, the occurrence of EPs in aquatic biota has not been widely studied. This is probably because their complexity, due to the presence of lipids, proteins and other organic compounds, makes the extraction and analysis of EPs difficult. This review gathers the most relevant analytical methods published between 2014 and 2019, comparing them and evaluating their strengths and weaknesses. It is intended to provide a better understanding of the development of new and improved methods, and to be a reference for researchers who are looking for the best methodology for their studies.     

Organotin speciation in aquatic matrices by CGC/FPD, ECD and MS, and LC/MS

Summary The sensitivity and reproducibility of CGC coupled to selective detectors for the determination of alkyl and aryltin compounds (R_xSnY_z, where R=C₄H₉ or C₆H₅, and Y=CH₃ or Cl) (x+z=4) have been evaluated. In this regard, single or dual flame FPD configurations, with or without interference filter (600 nm) have been compared. The electron impact (EI) selected ion monitoring detection (SIM) CGC-MS was also considered for confirmation of the FPD assignments as well as for quantitative purposes. Alternatively, the accuracy and sensitivity of the direct analysis of organotin chlorides (Y=Cl) by cold on-column injection CGC-ECD or by thermospray LC-MS were determined. According to this, an analytical protocol based on acid digestion, extraction with organic solvents modified with tropolone, derivatization with CH₃MgCl, cleanup with alumina and CGC-FPD analysis has been successfully applied to the characterization of organotin compounds in seawater, sediments and biota. The relative detection limits of the whole procedure were dependent of the tin species and the environmental compartment considered, ranging from 0.5 to 6.5 ng l^–1 for seawater, in the filterless operation mode, and 0.1–2 ng g^–1 and 0.7–8 ng g^–1 for sediments and biota, respectively, using a 600 nm interference filter. Reproducibility was in the range of 15% RSD. Aryl and hydroxyalkyltin were identified for the first time in the aquatic compartments.     

Assessment of the Effects of Chitosan,Chitooligosaccharides and Their Derivatives on Lemna minor

Chitosan, chitooligosaccharides and their derivatives’ production and use in many fields may result in their release to the environment, possibly affecting aquatic organisms. Both an experimental and a computational approach were considered for evaluating the effects of these compounds on Lemna minor. Based on the determined EC₅₀ values against L. minor, only D-glucosamine hydrochloride (EC₅₀ = 11.55 mg/L) was considered as “slightly toxic” for aquatic environments, while all the other investigated compounds, having EC₅₀ > 100 mg/L, were considered as “practically non-toxic”. The results obtained in the experimental approach were in good agreement with the predictions obtained using the admetSAR2.0 computational tool, revealing that the investigated compounds were not considered toxic for crustacean, fish and Tetrahymena pyriformis aquatic microorganisms. The ADMETLab2.0 computational tool predicted the values of IGC₅₀ for Tetrahymena pyriformis and the LC₅₀ for fathead minnow and Daphnia magna, with the lowest values of these parameters being revealed by totally acetylated chitooligosaccharides in correlation with their lowest solubility. The effects of the chitooligosaccharides and chitosan on L. minor decreased with increased molecular weight, increased with the degree of deacetylation and were reliant on acetylation patterns. Furthermore, the solubility mainly influenced the effects on the aqueous environment, with a higher solubility conducted to lower toxicity.     

Combining reverse osmosis and pulsed electrical current electrodialysis for improved recovery of dissolved organic matter from seawater

Dissolved organic carbon (DOC) in the oceans is one of the largest dynamic reservoirs of carbon on earth, comparable in size to the atmospheric reservoir of carbon (as CO₂) in the atmosphere, or to the amount of carbon in all terrestrial and aquatic biota. The concerted efforts of earth scientists, atmospheric scientists, and biologists who study global biogeochemical cycles and the earth's climate have yielded a rather detailed understanding of carbon in the atmosphere and in biota. Marine dissolved organic matter (DOM) is far less well characterized, principally because it exists as a highly diluted mixture of perhaps millions of organic compounds in a highly saline aqueous solution. Prior to 2007, only around 1/3 of marine DOM was typically recovered from seawater for research purposes, regardless of the method of isolation. In 2007, reverse osmosis (RO) and electrodialysis (ED) were coupled to achieve recoveries of 64–93% of marine DOM. The level of residual salts in the concentrated samples, however, still precluded the characterization of marine DOM by solid-state NMR, mass spectrometry, or even elemental analysis. This paper describes a major improvement to the RO/ED method, in which pulsed ED is used (at sea) to reach roughly 100-fold greater removal of salts compared to non-pulsed ED while maintaining comparable recoveries of DOM.     

Microplastics and associated emerging contaminants in the environment: Analysis,sorption mechanisms and effects of co-exposure

Microplastics (MPs) and other emerging pollutants exist together in the environment and their co-exposure represents a source of increasing concern as MPs have been reported to act as carriers of pollutants due to their high sorption capacity. The ingestion of contaminated MPs by organisms can enhance the desorption of pollutants, increasing their bioavailability and toxicity. This review examines the role of MPs as vectors of environmental emerging contaminants. First, the main tools used to identify and characterise MPs and the analytical methods used for the determination of associated emerging contaminants are discussed. Insightful explanations of the sorption interaction between several groups of emerging pollutants and MPs are provided. MP type (polarity, crystallinity, size) and aging process together with the environmental conditions and pollutant properties (hydrophobicity and dissociated forms) are key factors influencing the sorption process. The literature review showed that polyethylene and polystyrene were the most commonly studied polymers. Antibiotics, perfluoroalkyl compounds and triclosan showed high sorption capacities onto MPs. Finally, the effect of co-exposure to MPs-emerging pollutants and bioaccumulation in aquatic and terrestrial organisms is discussed. The combined exposure may impact the toxic effects in different ways, through synergistic or antagonic interactions. Examples of different scenarios are provided, but in general the research conducted on terrestrial systems is scarce. The results revealed a lack of standardization in laboratory studies and in the testing conditions that reflect actual environmental exposure.     

Crystal structure and electrochemical properties of rare earth non-stoichiometric AB5-type alloy as negative electrode material in Ni-MH battery

The La_0.85Mg_xNi_4.5Co_0.35Al_0.15 (0.05?x?0.35) system compounds have been prepared by arc melting method under Ar atmosphere. X-ray diffraction (XRD) analysis reveals that the as-prepared alloys have different lattice parameters and cell volumes. The electrochemical properties of these alloys have been studied through the charge-discharge recycle testing at different temperatures and discharge currents. It is found that the La_0.85Mg_0.25Ni_4.5Co_0.35Al_0.15 alloy electrode is capable of performing high-rate discharge. Moreover, it has very excellent electrochemical properties as negative electrode materials in Ni-MH battery at low temperature, even at −40°C.     

Probing the binding sites and coordination limits of buckybowls in a solvent-free environment: Experimental and theoretical assessment

This work overviews the coordination properties of fullerene fragments or buckybowls, a new class of open geodesic polyaromatic hydrocarbons that map onto the surface of fullerenes but lack their full closure. In contrast to fullerenes, the bowl-shaped polyarenes have both the convex and concave unsaturated carbon surfaces open and available for coordination, which makes them unique and interesting π-ligands for metal binding reactions. Variable synthetic methods based on solution and solid-state reactions have been developed to access transition metal complexes of buckybowls and to reveal their coordination properties. These studies have been mainly focused on the smallest fragments of the C₆₀-fullerene, corannulene (C₂₀H₁₀) and sumanene (C₂₁H₁₂). In order to utilize directional metal–π-arene interactions effectively and to differentiate π-bonding sites of buckybowls, we have introduced a micro-scale gas-phase deposition method. We have proven this technique to be very effective for the preparation of metal complexes of buckybowls in a single crystalline form. Plus, it allowed us to expand the coordination studies to larger bowls, including dibenzo[a,g]corannulene (C₂₈H₁₄), monoindenocorannulene (C₂₆H₁₂), and the C₃-symmetric hemifullerene (C₃₀H₁₂). Specifically, several dimetal core complexes of varied electrophilicity have been used in the gas-phase coordination reactions to identify the preferential binding sites and to test the coordination limits of π-bowls in a solvent-free environment. The coordination preferences of several buckybowls having different surface area and bowl depth, as well as different curvature and strain are compared and discussed here based on the results of X-ray diffraction and DFT calculation studies.     

Bioaccumulation of antimony, arsenic, and mercury in the vicinities of a large antimony mine, China

To study the characteristics of antimony (Sb) bioaccumulation under high Sb background values, aquatic, amphibious and terrestrial biological samples were collected in the vicinity of the Xikuangshan (XKS) Sb mine area in China. Hydride generation-atomic fluorescence (HG-AFS) analysis showed that Sb concentrations in terrestrial invertebrates (average 30,400 μg kg^− 1 dry wt.) were higher than those in aquatic (average 5200 μg kg^− 1 dry wt.) and amphibian (average 2300 μg kg^− 1 dry wt.) biological samples. Within 1 km distance of the XKS Sb mine area, grasshoppers (Acrida chinensis) and earthworms (Pheretima aspergillum) had the highest Sb amounts of 17,300 ±3200 and 43,600 ± 47,700 μg kg^− 1 dry wt., respectively. No Sb biomagnifications were observed. The bioavailability of Sb was found to be lower than those of As and Hg. A preliminary conclusion is that antagonistic effects exist between Sb and Hg accumulation in biological samples from aquatic environments. Our study is the first to report such antagonistic effects between Sb and Hg. If this deduction proves to be correct, it should be taken into consideration in assessing human health risks, especially when Sb and Hg concentrations in the aquatic environments are high.     

The use of k0-INAA for determination of surface contamination of some aquatic plants by trace elements

Adsorption of fine suspended material on the surface of aquatic plants may lead to great problems in the interpretation of results for their trace element composition, since it is quite impossible to clean the inorganic material from the biota completely. A carefully designed field experiment was performed in the River Stella in North-Eastern Italy aimed at studying the adsorption of fine suspended material on benthic algae-periphyton. More than 20 elements, were determined in water, suspended material and biota using k ₀-INAA, and enrichment factors were calculated for selected elements using Sc as a normalizing element.     

Bioassay-guided isolation of human carboxylesterase 2 inhibitory and antioxidant constituents from Laportea bulbifera: Inhibition interactions and molecular mechanism

Laportea bulbifera (Sieb. et. Zucc.) Wedd has long been utilized in Traditional Chinese Medicines (TCM) for the treatment of rheumatoid arthritis. However, the study of systematic anti-inflammatory chemical constituents in L. bulbifera has never been reported. Thus, bioassay-guided isolation for its roots part led to 46 compounds, including 38 phenolic derivatives. Their structures were determined on the basis of ¹H and ¹³C NMR and MS spectra. All compounds were isolated from L. bulbifera for the first time except for 13 compounds. Most of the compounds showed good COX-2 inhibitory activity (IC₅₀: 0.13–3.94 μM) and DPPH radical-scavenging activity (IC₅₀: 1.57–9.55 μM). Four compounds (4, 17, 35, and 43) with different skeletons showed preferential COX-2 over COX-1 inhibition with selective indices ranging from 12 to 171. High content active compounds are important for elucidating the basis of the active substance of TCM. Compound 4 (COX-2, IC₅₀ 0.24 μM), a high content compound, represented one of the best selective COX-2 inhibitors. Another high content active compound (35) with a different skeleton might have different mechanism. Further study for the inhibition kinetics against COX-2 indicated compounds 4 and 35 were noncompetitive and competitive COX-2 inhibitors, respectively. Moreover, molecular docking and molecular dynamics simulation data further indicated that compound 4 could bind in the cavity of COX-2 and interacted with key residues VAL-538, PHE-142, and GLY-225 of COX-2 through hydrogen bonds. The results indicated that L. bulbifera roots could be applied as antioxidant and anti-inflammatory agents due to their potent selective COX-2 inhibitory and antioxidant activity of phenolic compounds.     

Cation-anion palladium complexes: the effect of the hydrogen bond character on their stability and biological activity

The results of study of a new class of biologically active palladium complexes (AH _n ) _m [PdCl₄] have been reported. This class of compounds has been discovered by us on the basis of systemic research of composition-structure-biological activity relationships for different classes of platinum metal complexes. It has been shown that the stability of cation-anion palladium complexes and their biological activity are determined by the nature of protonated amines acting as cations and the acid-base properties of the cations-tetrachloropalladate anion systems, manifested in the character and stability of hydrogen bonds that appear in these systems. For the first time, it has been demonstrated in vivo that it is possible to synthesize palladium compounds superior to cisplatin in antitumor activity and not exhibiting immunosuppressive activity, as well as palladium compounds with immunostimulatory and radiomodifying activity. A combination of cytostatics used in oncology or irradiation with palladium complexes leads to significant synergism of their effects and to a considerably higher therapeutic efficiency of such combinations as compared with the treatment effect of each of them alone.     

Synthesis,characterization, DNA interaction,thermal and in vitro biological activity investigation of some Ni(II)-Isatin bishydrazone complexes

Complexes of the type [Ni (L) (H₂O)] Cl₂.nH₂O, where L = [(pyridine-2-carboxaldhyde)-3-isatin]-bishydrazone (cpish), [(2-acetyl pyridine)-3-isatin]-bishydrazone (apish) and [(2-benzoyl pyridine)-3-isatin]-bishydrazone (bpish) have been synthesized and characterized on the bases of elemental analysis, molar conductance, IR, NMR, electronic spectra and thermal analysis (TGA and DTA). Moreover, the stoichiometry and the formation constants of these complexes have been determined spectrophotometrically. Kinetics and thermodynamic parameters of the thermal decomposition have been computed from the thermal data using Coats and Redfern method, which confirm first-order kinetics. The bioefficacy of the ligands and their complexes have been examined for their in vitro antibacterial and antifungal activity against many types of bacteria and anti fungal cultures, which are common contaminants of the environment in Egypt, and the results indicate that the ligands and their metal complexes possess notable antimicrobial activity. Investigation of their interaction with CT-DNA under physiological conditions, using spectroscopic (UV–visible) and hydrodynamic techniques (viscosity measurements). Binding constant "K _b" obtained from spectroscopic methods revealed significant binding of compounds with DNA via intercalation, Furthermore, free energies of compounds–DNA interactions indicated spontaneity of their binding.     

First-principle investigation of XSrH3 (X = K and Rb) perovskite-type hydrides for hydrogen storage

Hydrogen can be utilized as an energy source; therefore, hydrogen storage has received the most appealing examination interest in recent years. The investigations of hydrogen storage applications center fundamentally around the examination of hydrogen capacity abilities of recently presented compounds. XSrH₃ (X = K and Rb) compounds have been examined by density functional theory (DFT) calculations to uncover their different characteristics, as well as hydrogen capacity properties, for the first time. Studied compounds are optimized in the cubic phase, and optimized lattice constants are obtained as 4.77 and 4.99 Å for KSrH₃ and RbSrH₃, respectively. These hydrides have shown negative values of formation enthalpies as they are stable thermodynamically. XSrH₃ might be used in hydrogen storage applications because of high gravimetric hydrogen storage densities, which are 2.33 and 1.71 wt% for KSrH₃ and RbSrH₃, respectively. Moreover, electronic properties confirm the semiconductor nature of these compounds having indirect band gaps of values 1.41 and 1.23 eV for KSrH₃ and RbSrH₃, respectively. In addition, mechanical properties from elastic constants such as Young modulus and Pugh's ratio, also have been investigated, and these compounds were found to satisfy born stability conditions. Furthermore, Pugh's ratio and Cauchy pressure show that these hydrides have a brittle nature. Furthermore, thermodynamic properties such as entropy and Debye temperature have been examined using the quasiharmonic Debye model for different temperatures and pressures.