DNA adducts in fish following an oil spill exposure

On 12 December 1999, one third of the load of the Erika tanker, amounting to about 10,000 t crude oil flowed into sea waters close to the French Atlantic Coast. This oil contained polycyclic aromatic compounds (PAC) that are known to be genotoxic. Genotoxic effects induce DNA adducts formation, which can thus be used as pollution biomarkers. Here, we assessed the genotoxic impact of the “Erika” oil spill by DNA adducts detection in the liver of immature fishes (Solea solea) from four locations of the French Brittany coasts. Two months after the spill, a high amount of DNA adducts was found in samples from all locations, amounting to 92–290 DNA adduct per 109 nucleotides. Then total DNA adduct levels decreased to reach about 50 adducts per 109 nucleotides nine months after the spill. In vitro experiments using human cell cultures and fish liver microsomes evidence the genotoxicity of the Erika fuel. They also prove the formation of reactive species able to create DNA adducts. Furthermore, in vitro and in vivo DNA adducts fingerprints are similar, thus confirming that DNA adducts are a result of the oil spill

Biomarkers in Natural Fish Populations Indicate Adverse Biological Effects of Offshore Oil Production

Despite the growing awareness of the necessity of a sustainable development, the global economy continues to depend largely on the consumption of non-renewable energy resources. One such energy resource is fossil oil extracted from the seabed at offshore oil platforms. This type of oil production causes continuous environmental pollution from drilling waste, discharge of large amounts of produced water, and accidental spills.Samples from natural populations of haddock (Melanogrammus aeglefinus) and Atlantic cod (Gadus morhua) in two North Sea areas with extensive oil production were investigated. Exposure to and uptake of polycyclic aromatic hydrocarbons (PAHs) were demonstrated, and biomarker analyses revealed adverse biological effects, including induction of biotransformation enzymes, oxidative stress, altered fatty acid composition, and genotoxicity. Genotoxicity was reflected by a hepatic DNA adduct pattern typical for exposure to a mixture of PAHs. Control material was collected from a North Sea area without oil production and from remote Icelandic waters. The difference between the two control areas indicates significant background pollution in the North Sea.It is most remarkable to obtain biomarker responses in natural fish populations in the open sea that are similar to the biomarker responses in fish from highly polluted areas close to a point source. Risk assessment of various threats to the marine fish populations in the North Sea, such as overfishing, global warming, and eutrophication, should also take into account the ecologically relevant impact of offshore oil production

Polymorphism in polymers : its implications for polymer crystallisation

The aim of this article is to extend the earlier reported observations on the role of transient metastable phases in polymer crystallisation in relation with the initial crystal size. In this article experimental evidence is provided to bridge the gap between single crystal formation in the melt at elevated pressure and temperatures vs. crystallisation at atmospheric pressure using polyethylene as a model substance. During transformation from the hexagonal to the orthorhombic phase it is shown that in the process of growth, a crystal goes through thermodynamically stable and metastable states before transformation to the orthorhombic phase occurs. The crystal growth, on transformation to the thermodynamically stable orthorhombic phase, has been followed with the help of in-situ optical microscopy and transmission electron microscopy. The observations are that the newly transformed crystal acts as a nucleation centre for many new crystals starting in the hexagonal phase. It is also noticed that with increasing supercooling multilayering dominates. Subsequently, the distinction between primary and secondary thickening has been made and its morphological consequences will be discussed. In its wider generality, the experimental findings indicate that in polyethylene at atmospheric pressure crystallisation occurs via the hexagonal phase. When extended to atmospheric pressure, the morphological features give further insight into spherulite formation. The observations have been extended to other polymers such as nylon, paraffins, poly-di-alkyl siloxanes, trans-1,4 polybutadiene etc. The proposed viewpoint on the crystal size influence in phase transition has been extended to polymer processing as will be illustrated briefly for the case of processing of the intractable polymer ultra-high-molecular-weight polyethylene (UHMW-PE)

Temperature-modulated differential scanning calorimetric measurements on nascent ultra-high molecular mass polyethylene

Temperature-modulated differential scanning calorimetric (TMDSC) measurements on nascent ultra-high molecular mass polyethylene (UHMMPE) in scanning as well as quasi-isothermal mode are presented. From these measurements, a special irreversible relaxation process in the pre-melting region can be separated, which only occur on the first heating of the nascent material. The frequency dependence of this process yield a characteristic time constant of 6.5 s (or 24 mHz) which fits with the a2-process known from mechanical measurements. Quasi-isothermal measurements show that there are two slow (exponential) relaxation processes with time constants of 2–5 and several hundred minutes, respectively. The latter is only found in the first run of nascent UHMMPE and seems to be connected with irreversible structural changes (crystal thickening and ordering). The low activation energy (ca. 50 kJ mol-1) points to a chain diffusion process rather than melting and crystallization

Chain mobility in polymer systems : on the borderline between solid and melt 3. Phase transformations in nascent ultrahigh molecular weight polyethylene reactor powder at elevated pressure as revealed by in-situ Raman spectroscopy

The phase transformations under elevated pressure have been followed in situ by X-ray and Raman spectroscopy for ultrahigh-molecular-weight polyethylene (UHMW-PE) reactor powder. Using the in situ X-ray as a reference for the Raman work, it has been shown that Raman spectroscopy is a convenient method to follow phase transformations in polyethylene under pressure. The distinction has been made between different solid phases in polyethylene (monoclinic, orthorhombic, and hexagonal phases) and the melt by studying the conformational changes occurring within the skeletal mode (1000-1200 cm-1) upon the phase transformations. The crystal field splitting (1415/1440 cm-1) in the -CH2- bending mode of the Raman spectrum of polyethylene, related to the orthorhombic unit cell, was confirmed to be sensitive to transformations between different crystal structures. By following the changes occurring in the methylene bending mode together with the changes within the C-C skeletal mode, it has been shown that the crystalline phases and the melt can be mutually distinguished

Temperature-modulated differential scanning calorimetric measurements on pre-melting behavior of nascent ultrahigh molar mass polyethylene

Temperature-modulated differential scanning calorimetric (TMDSC) measurements on nascent ultrahigh molecular mass polyethylene (UHMMPE) in scanning as well as quasi-isothermal mode are presented. From these measurements different processes, which contribute to the modulated heat flow in the pre-melting region, both exothermic and endothermic in character, can be separated. One of them only occur on the first heating of the nascent material. Analysis of quasi-isothermal measurements, performed between 90 and 130 °C, show that there are two slow (exponential) relaxation processes with time constants of 2–5 and 10–100 min, respectively. One, exothermic in character, seems to be connected with irreversible structural changes (crystal thickening and ordering). The low activation energy (ca 40 kJ mol-1) points to a chain diffusion process rather than melting and crystallization. The other process (activation energy 60 kJ mol-1) seems to be endothermic. In the melting region, a slow (>100 min) 3rd relaxation process with high activation energy (300 kJ mol-1) can be separated