No 2 (2024)

The research goal is the investigation of environmental processes of recent sedimentation in the Arctic Ocean area. A short core (length – 37 cm) was taken from the Northern part of the Chukchi Sea. Analytical methods included macroscopic sedimentological description by smear-slides, dating by γ-measurements of ¹³⁷Cs and ²¹⁰Pb, diatom and palynological analyses. Sedimentation rates at the research site have been determined to be 1 mm y^-1. Thus, the age of the cored sediments spans approximately 400 years, which includes the period of the Little Ice Age. Abundant cold-water diatom species and spores of terrestrial plants within the lower part of the sediment core are characteristic for cold climate conditions, which dominated the Little Ice Age. The occurrence of Jurassic, Cretaceous, and Neogene species of spores and pollen in the Holocene deposits are the evidence of coastal abrasion and the subsequent transfer of the material to the coring site by currents. Southern, subtropical, and tropical species of diatoms within the upper, more recent part of the core reveal the transfer of material by currents from the Pacific Ocean to the Arctic Ocean through the Bering Strait. The results of biostratigraphic analyses indicate environmental changes during the last 400 years, revealed in bottom sediments of the Northern part of the Chukchi Sea.

The objective of the study was to evaluate the water quality status and the aquatic arthropod species composition of the Idim Eye-Asana River, Edebom 1, between May and July 2023. The sampling area was divided into four (4) sampling sites with unique coordinates. The physico-chemical parameters such as dissolved oxygen (DO), pH, temperature, total dissolved solute (TDS), inorganic contents; nitrate, sulphate, nitrite, and phosphate were measured using standardised methods. The aquatic arthropod specimens were collected using standardised circular-framed net with a 0.05µm mesh size and 35cm in diameter with an iron handle of 2m in length. Single factor pollution index (Pi), Biological Monitoring Working Party (BMWP) index, and diversity indices were calculated to evaluate the water quality status of the river. The physico-chemical parameter results revealed that they were differently significant between the sampling sites. The inorganic contents (contaminants) results showed that nitrate, phosphate, nitrite, and sulphate were differently significant at a 95% t-test between the sampling sites. The Pi values for the inorganic contents revealed that the water quality at site 2 was moderately polluted (3.25) with nitrite, whereas sites 3 (2.85) and 4 (2.50) were lightly polluted. Three (3) arthropod classes, sorted into seven (7) orders, and thirty-four (34) families were collected. Through the BMWP index results, the water quality classification for the water status at site 1 was regular (moderately contaminated), site 2 (poor), and sites 3 and 4 (Good water quality). Sites 3 and 4 sections of the river had good water quality, and as indicated by the results, it was concluded that the sites (i.e., 3 and 4) have better ecological conditions that can sustain the development and survival of the aquatic arthropod species.