Spatio-temporal dynamics and behavioural ecology of a "demersal" fish population as detected using research survey pelagic trawl catches: The Eastern Baltic Sea cod (Gadus morhua)

Cod is usually monitored for scientific purposes using bottom trawl surveys, although its regular pelagic occurrence is well documented. Here we analysed, using Generalized Additive Models, the spatio-temporal changes in the Eastern Baltic cod adult population using pelagic catches from an acoustic survey covering 37 years and the whole central Baltic Sea. Our analysis shows that in the northern areas cod catch per unit effort (CPUE, kg h-1) was high in the early 1980s whereas it dropped and remained very low thereafter. Conversely, in the southernmost area CPUE largely oscillated after the early 1990s. Our model was able to capture key ecological features of the Baltic cod such as preferred depth of occurrence and response to hypoxic conditions. The model also revealed a clear daily cycle of CPUEs, indicating diel vertical migrations at the population level. The temporal trends of pelagic CPUEs generally followed those from the bottom trawl surveys, although differences were observed especially in the recent years with a relative decline in the cod occurring in the pelagic waters. Our results point to the great potential of acoustic survey trawl catches to complement bottom trawl surveys for investigating the spatio-temporal population dynamics and behaviour of the Baltic cod

Influence of sorbent nature on platinum group metals reversible dynamic sorption preconcentration with subsequent determination by inductively coupled plasma mass-spectrometry

Исследована сорбция Ru, Rh, Pd, Ir, Pt и Au в виде ионных ассоциатов, образованных хлоридными комплексами металлов с реагентами: третичными аминами и четвертичными аммониевыми основаниями (ЧАО). Использованы третичные амины - трибутиламин (ТБА),4-(н-октил)диэтилентриамин (ОДЭТА), и ЧАО - цетилтриметиламмоний бромид (ЦТАБ). Проведены исследования на сорбентах ДИАПАК С₁₆, ССПС MN-200 и StrataX. Изучена возможность динамического сорбционного концентрирования платиновых металлов с разбавлением в потоке. Показано, что обратимое количественное извлечение Pd, Pt и Au возможно в системе ТБА-ССПС при десорбции 1 М раствором соляной кислоты в 96 % этиловом спирте. Количественного обратимого извлечения Ru, Rh, Ir достичь не удалось.The sorption of Ru, Rh, Pd, Ir, Pt, Au as ion associates, formed by metals chloro complexes with different N-reagents, was studied. The tertiary amine - tributylamine, the quaternary ammonium compound - cetyltrimethylammonium bromide, and the triamine - 4-(n-octyl)diethylenetriamine were used as reagents to form the hydrophobic compounds with PGM chloro complexes. These compounds were extracted from acid solutions with the use of the low-polarity sorbents Diasorb С₁₆ and hypercrosslinked polysterene MN-200. Dynamic sorption preconcentration of PGM with dilution in the flow was investigated. It was revealed that only tributylamine, hypercrosslinked polysterene MN-200 and 1 M HCl in ethanol provided the quantitative and reversible sorption of Pd, Pt and Au. Quantitative and reversible extracrion of Ru, Rh, Ir was not achieved