A century of otolith-derived temperature exposure of Icelandic and Norwegian cod (Gadus morhua)

<p>Increasing water temperatures are predicted around the globe with high amplitudes of warming in Subarctic and Arctic regions where Atlantic cod (<em>Gadus morhua</em>) populations currently flourish. We reconstructed population abundance, oxygen isotope and temperature chronologies from otoliths of the two largest cod populations in the world - the Icelandic and the Northeast Arctic (NEA) cod - to determine if their temperature selectivity over the last 100 years was driven by rising water temperatures and/ or changes in abundance. For δ<sup>18</sup>O<sub>otolith </sub>analysis, individual annual growth increments from immature and mature life history stages of cod collected in southern Iceland and the Lofoten area (Norway) were micromilled from adult otoliths. Ambient temperatures of Icelandic and Norwegian cod were reconstructed using otolith δ<sup>18</sup>O. Linear mixed effect models were applied to identify and quantify the density-dependent temperature selectivity of both cod populations. The results indicated that Icelandic cod migrated into warmer waters with increasing abundance (<em>p</em> < 0.05), whereas NEA cod moved into colder waters (<em>p</em> < 0.001). The temperature selectivity of NEA cod was also significantly correlated with water temperatures at 0-200 m depth (<em>p</em> < 0.001), indicating that NEA cod were at least partially exposed to increasing ocean temperatures due to global warming. Stable oxygen isotope and ambient temperature chronologies can be an important tool for sustainable management plans in terms of future global warming as it can be used to predict re-distribution as oceans warm.</p>

Temperature selectivity for single phase hydrothermal synthesis of PEG-400 coated magnetite nanoparticles

Temperature plays a vital role in the hydrothermal synthesis of the nanoparticles. Herein, we have provided a very detailed spin dynamic investigation on the varying size Fe3O4 nanoparticles using FMR technique.

Synthesis and Regeneration of Nickel-Based Catalysts for Hydrodeoxygenation of Beech Wood Fast Pyrolysis Bio-Oil

Four nickel-based catalysts are synthesized by wet impregnation and evaluated for the hydrotreatment/hydrodeoxygenation of beech wood fast-pyrolysis bio-oil. Parameters such as elemental analysis, pH value, and water content, as well as the heating value of the upgraded bio-oils are considered for the evaluation of the catalysts’ activity and catalyst reuse in cycles of hydrodeoxygenation after regeneration. The reduction temperature, selectivity and hydrogen consumption are distinct among them, although all catalysts tested produce upgraded bio-oils with reduced oxygen concentration, lower water content and higher energy density. Ni/SiO2, in particular, can remove more than 50% of the oxygen content and reduce the water content by more than 80%, with low coke and gas formation. The evaluation over four consecutive hydrotreatment reactions and catalyst regeneration shows a slightly reduced hydrodeoxygenation activity of Ni/SiO2, mainly due to deactivation caused by sintering and adsorption of poisoning substances, such as sulfur. Following the fourth catalyst reuse, the upgraded bio-oil shows 43% less oxygen in comparison to the feedstock and properties comparable to the upgraded bio-oil obtained with the fresh catalyst. Hence, nickel-based catalysts are promising for improving hardwood fast-pyrolysis bio-oil properties, especially monometallic nickel catalysts supported on silica.

Modification of Polyacrylamide–β–Zeolite Composite by Phytic Acid for the Removal of Lead from Aqueous Solutions

Polyacrylamide-zeolite composite was prepared by direct polymerization of polyacrylamide in suspensions of β-zeolite. Phytic acid was then immobilized on the composite surface. Fourier transform infrared spectrometry (FT-IR), X-Ray Diffraction (XRD) and Thermal gravimetry (TG) techniques were employed to characterize the synthesized adsorbent. The adsorptive features of the composite and the modified composite were investigated for the removal of Pb2+ from aqueous solution in view of dependency on pH, time, ion concentration, temperature, selectivity, kinetics and reusability. The adsorption isotherms were evaluated with reference to the Langmuir and Freundlich models. Thermodynamic of the system was calculated. ΔG<0 indicated that the adsorption process was spontaneous. Good compatibility of the adsorption kinetics to the pseudo-second-order model predicted that the rate-controlling step was a chemical sorption. The selectivity experiments showed that the adsorbents were selective toward Pb2+ in the presence of Zn2+ and Cd2+. The reusability of the adsorbent was tested for four regeneration cycles.