Shelf basin exchange along the Siberian continental margin: modification of Atlantic Water and Lower Halocline Water

Highlights • Atlantic Water modified by sea-ice melt and meteoric water at Barents Sea slope • LHW may be divided into different types by Principal Component Analysis (PCA) • high salinity LHW-type forms in the Barents and Kara seas • low salinity LHW-types form in the western Laptev Sea or enter via Vilkitsky Strait • PCA does not support a distinction between onshore and offshore LHW branches Abstract Salinity and stable oxygen isotope (δ18O) evidence shows a modification of Atlantic Water in the Arctic Ocean by a mixture of sea-ice meltwater and meteoric waters along the Barents Sea continental margin. On average no further influence of meteoric waters is detectable within the core of the Atlantic Water east of the Kara Sea as indicated by constant δ18O, while salinity further decreases along the Siberian continental slope. Lower halocline waters (LHW) may be divided into different types by Principal Component Analysis. All LHW types show the addition of river water and an influence of sea-ice formation to a varying extent. The geographical distribution of LHW types suggest that the high salinity type of LHW forms in the Barents and Kara seas, while other LHW types are formed either in the northwestern Laptev Sea or from southeastern Kara Sea waters that enter the northwestern Laptev Sea through Vilkitsky Strait. No further modification of LHW is seen in the eastern Laptev Sea but the distribution of LHW-types suggest a bifurcation of LHW at this location, possibly with one branch continuing along the continental margin and a second branch along the Lomonosov Ridge. We see no pronounced distinction between onshore and offshore LHW types, as the LHW components that are found within the halocline over the basin also show a narrow bottom-bound distribution at the continental slope that is consistent with a shelf boundary current as well as a jet of water entering the western Laptev Sea from the Kara Sea through Vilkitsky Strait

Physical oceanography, nutrients, and δ¹⁸O measured on water bottle samples in the Laptev Sea

Large gradients and inter annual variations on the Laptev Sea shelf prevent the use of uniform property ranges for a classification of major water masses. The central Laptev Sea is dominated by predominantly marine waters, locally formed polynya waters and riverine summer surface waters. Marine waters enter the central Laptev Sea from the northwestern Laptev Sea shelf and originate from the Kara Sea or the Arctic Ocean halocline. Local polynya waters are formed in the Laptev Sea coastal polynyas. Riverine summer surface waters are formed from Lena river discharge and local melt. We use a principal component analysis (PCA) in order to assess the distribution and importance of water masses within the Laptev Sea. This mathematical method is applied to hydro‐chemical summer data sets from the Laptev Sea from five years and allows to define water types based on objective and statistically significant criteria. We argue that the PCA‐derived water types are consistent with the Laptev Sea hydrography and indeed represent the major water masses on the central Laptev Sea shelf. Budgets estimated for the thus defined major Laptev Sea water masses indicate that freshwater inflow from the western Laptev Sea is about half or in the same order of magnitude as freshwater stored in locally formed polynya waters. Imported water dominates the nutrient budget in the central Laptev Sea; and only in years with enhanced local polynya activity is the nutrient budget of the locally formed water in the same order as imported nutrients

Leading causes of death in older people and old age according to medical certificates of death in Moscow

BACKGROUND: The proportion of older people is increasing worldwide. Leading causes of death must be understood for the organization of medical and social care. AIM: This study aimed to identify and discuss the leading causes of death in older people and old age based on data from medical death certificates. MATERIAL AND METHODS: From the electronic database of the Main Department of the Civil Registry Office of the Moscow Region (the system of the Unified State Register of Civil Status Records), all cases in which diseases were indicated as the initial cause of death (all codes of external causes, injuries, and poisoning were excluded) were selected. From a total of 109,126 deceased individuals, 90,269 (82.7%) were 60 years old. Eighteen groups of initial causes of death were made (95.2% of deaths from diseases); 40,442 (44.8%) medical death certificates were issued by the Bureau of Forensic Medicine. \ud RESULTS: Five leading causes of death were COVID-19 (24.2%), pathologies associated with cognitive impairment and dementia (21.15%; aged 6069 years, 6.02%; aged 100 years, 63.5%), chronic ischemic heart disease (18.6%), malignant neoplasms (10.7%; aged 6069 years, 16.7%; aged 100 years, 1.46%), and acute cerebrovascular accident (6.2%). The contribution of causes such as acute forms of coronary artery disease, stroke, hypertension, diabetes mellitus, COVID-19, and others is low in older people. Only 30% of the medical death certificates have their part II completed. The probability of filling out part II of the medical death certificate is influenced by age, place of death, place of issuance of the medical death certificates (in the Bureau of Forensic Medicine less than in other medical organizations), and teaching staff. With age, the proportion of MCAs issued by the Bureau of Forensic Medicine is increasing. Medical death certificates often use codes that are not analogous to clinical diagnoses. CONCLUSION: The contribution of individual causes (and groups of causes) of death changes with age. For a better understanding of the leading causes of death, a multidisciplinary consensus is needed in determining the criteria and validity of the use of the International Statistical Classification of Diseases and Health-Related Problems, Tenth revision, codes

Nutrients, oxygen, total alkalinity, pH, and physical oceanography measured on water bottle samples during Akademik Tryoshnikov cruise Arctic Century 2021 Expedition (AT21), Arctic Ocean

A standard CTD system from Sea-Bird Electronics Inc SBE911+ with duplicate temperature and conductivity sensors was used to measure temperature, conductivity and pressure at 81 stations during an expedition to the Kara and Laptev Seas and the adjacent Arctic Ocean in August-September 2021 aboard the research vessel Akademik Tryoshnikov. We followed the recommendation of the manufacturer to calculate salinity with Seabird processing software. The salinity is given as Practical Salinity (PSU). The accuracy of the conductivity sensors was verified by measurements on water samples with a salinometer. The data set published here includes only the data from the first conductivity (SN 3290) and temperature (SN 4127) sensors. Only at station 26 the data of the second sensor pair (SN 2618/Cond, SN 5115/Temp) were used. The CTD was connected to a SBE32 Carousel Water Sampler with 24 12-liter bottles. Additionally, a Benthos Altimeter and a Wetlabs ECO-AFL Fluorometer were connected to the SBE911+ system. At 69 stations, 846 seawater samples were collected for analysis of dissolved inorganic nutrients (nitrate, nitrite, phosphate, ammonium, silicate), oxygen, total alkalinity, and pH. Dissolved inorganic nutrients were analyzed using a segmented flow analyzer from Seal Analytical. Ammonium was measured manually (colorimetric method) using a spectrophotometer (Shimadzu UV-1800). Dissolved oxygen was determined by the standard Winkler titration method using a Metrohm 916 TiTouch automatic titrator and a handheld titrator (BRAND). pH and total alkalinity were measured by potentiometric titration using an automatic titrator (Metrohm 916 TiTouch). The data are provided by the Arctic Century Expedition, a joint initiative led by the Swiss Polar Institute (SPI), the Antarctic and Arctic Research Institute (AARI) and GEOMAR Helmholtz Centre for Ocean Research Kiel (GEOMAR) and funded by the Swiss Polar Foundation, AARI, Minobrnauki (CATS RFMEFI61619X0108) and BMBF (CATS 03F0831)