The very first experience of biological analysis of water in Saint-Petersburg

The biological method of water quality analysis, for the first time, was applied in Russia during the examination of Neva Bay of the Gulf of Finland in the Baltic Sea by Wislouch S.M. Neva River was a source of drinking water in St. Petersburg and, at the same time, a discharge for all city drains. As a result, it became hazardous to health, being a source of various diseases, especially cholera. From August 1911 to September 1912 pollution studies of the Bay were made to solve the question - where to send the treated waste water of the future sewage system of St. Petersburg. In total, 37 trips were made during this time, 510 samples were taken, including 375 plankton samples and 35 benthic samples. Wysłouch S. M. gave an overview of objects collected at 265 stations located in the area of Neva Bay - from estuary of Bolshaya Neva to Kronstadt, along the southern coast of the Bay and partially along the Northern coast. He brought a list of algae, including 97 species: Algae Cyanophyceae (writing all taxa retained on original source) – 17 species, Flagellata – 19 species, Peridineae – 1, One – 30, Conjugatae – 2, Diatomaceae – 28 species, Fungi (1), Bacteria (17), Protozoa (28), Rotatoria (17). Taking into account the algae and other organisms saprobity indices, areas with different degrees of contamination were identified. All the data was put on map of the Gulf. The most heavily polluted area was the Sea channel, and the area between the Lisij Nos and Kronstadt was the cleanest.

Model studies of flow parameters in the area of bridge supports

The results of laboratory modeling of the influence of the bridge crossing supports erected during the construction of the highway near the existing railway bridge on the flow characteristics in the channel of the Neva River are presented. Modeling was carried out for two options for the location of the new bridge supports relative to the existing bridge structures. The limits of changes in the characteristics of the river flow are taken into account - the maximum, minimum and residual flows and benchmarks of the water level in the channel. Studies have shown that the construction of the designed bridge supports in the channel does not cause significant changes in the flow structure. There is a redistribution of the flow rate in the sections of the existing and designed bridges. The average velocities in the navigable span of the existing bridge are somewhat reduced when new supports are built. The velocity diagram is aligned along the width of the central and side spans, and a vortex wake is more clearly formed in the area behind the supports.

Method for choosing a scheme of placing navigation signs on a section of inland waterways for navigating a vessel with a given navigation risk value

This paper is devoted to the method of choosing a scheme for placing navigation signs on sections of inland waterways to ensure the navigation of vessels with a given level of navigation risks. The methods used are known from the theory of probability and mathematical statistics for the assessment of navigation risks, which is proposed to be performed by stochastic methods, estimating the dis-placement of the center of the vessel's size and the variability of the maneuvering lane. It is shown that according to the results of mathematical modeling of the controlled movement of the vessel along the difficult for navigation section “Ivanovskie Porogi” on the Neva river, these navigation parameters are subject to the normal distribution law. This made it possible to reduce the problem of risk assessment to the problem of finding the probability of a random variable hitting the designated lane. A formal assessment of the navigational risk of navigating a vessel through a section that is difficult for navigation was carried out, on the ba-sis of which it is possible to judge the quality of the vessel's control and the prob-ability of the vessel going beyond the edge of the fairway. The results presented in this work were obtained during the implementation of the INFUTURE international project.

LITTLE-KNOWN PAGES OF THE BALTIC FLEET PARTICIPATION IN LENINGRAD’S DEFENSE

The relevance of the article is due to the fact that the domestic historiography rather weakly covers the participation of the Baltic Fleet tactical formations in the defense of Leningrad. As a rule, special attention is paid to the tragic events of the first weeks of the Great Patriotic War and to the loss of a significant part of the Baltic Fleet ships. In this regard, the proposed article focuses on the history of the defending Tallinn, the Moonsund Islands, the Hanko Island, as well as on the participation of the Baltic Fleet artillery units and formations in checking the advancing Wehrmacht parts. Special attention is paid to the role of Leningrad in the history of the Great Patriotic War. St. Petersburg was the capital of the Russian Empire for over two centuries. With its embankments of the Neva River, bridges, the Hermitage, the Winter Palace and dozens of other unique structures, it was not only the capital for two centuries but its largest cultural center as well. No Russian city causes such a multitude of literary associations as St. Petersburg, and then Leningrad. The siege of the city, where more than a million people died, was unlike any of the tragedies of this war. Sieging Leningrad in September 1941 the fascists condemned almost three million people to starvation; more than a third of them died of starvation and exhaustion, but did not surrender to the fascists. A significant amount of scientific literature, journalistic, memories, etc. are devoted to the coverage of the heroic battle for Leningrad. However, there are still quite a few pages of this war that, in our view, have not received sufficient coverage in domestic historiography.

NUMISMATIC MATERIALS FROM THE EXCAVATIONS AT THE PETER AND PAUL FORTRESS IN 2017 AND 2019 AND THEIR BEARING ON THE DATING OF THE CULTURAL LAYER

A log-and-earth fortress on Zayachy island in the Neva River mouth was erected in 1703 by direction of Peter the Great. The building works took a short period from early May to late August. The construction of the stone fortress started in 1706. In 2017 and 2019, in the course of archaeological excavations carried out by IHMC RAS, a unique cultural layer with remains of the first log-and-earth fortress was discovered on the territory of the Menshikov bastion. Among the most important finds there are 18 coins issued by Peter I, including 14 wire kopecks, three copper quarter-kopeck pieces, and one copper half-kopeck coin. Two more coins with denomination of 1/6 öre were issued by Charles Х of Sweden (fig. 1; table). This numismatic collection is a reliable dating material, allowing to identify the constructions found in the cultural layer as the first log- and-earth fortress of Peter the Great, that became the historical core of Saint Petersburg. Worthy of note is the presence in the collection of a number of coins minted with dies made with the same punches, and the absence of coins minted in 1703. The presence of Swedish coins may be indica- tive of the participation in the construction works of captive Swedish soldiers, who could have lost the coins. At the same time it cannot be excluded that these coins were brought to Zayachy island with earth from Nyenschanz, which was used as a source of building materials.

Analysis of the total phosphorus runoff in the Neva River

The paper deals with the problems of water quality assessment taking into account the features of hydrochemical information. The analysis of dynamics of total phosphorus into the Neva River runoff from 1978 to 2017 is presented.