The paper proposes methods for identifying urban river zones (URZ) and assessing their socio-environmental functions, based on geospatial data, including Landsat 8 satellite images, Aster Global DEM, city master plan materials, VSEGEI maps of Quaternary deposits (1 : 200000) and OpenStreetMap. Social, geomorphological and administrative approaches to the URZ delimitation are considered. The authors propose a combined method for determining URZ boundaries at the urban level using TWI, the “Valley Depth” tool, data on Quaternary deposits, and functional zoning maps. Authors also suggest their criteria for assessing the quality of URZ green infrastructure in terms of providing social and environmental functions using land cover data and functional zoning for the administrative boundaries of the city and the built-up urban core. URZ were defined for three model cities (Nizhny Novgorod, Volgograd, Khabarovsk). Authors calculated the area of land cover categories and functional zones of different social and environmental value. The article demonstrates conclusions about how large the contribution of URZ green infrastructure (GI) to the total volume of urban GI ecosystem services is and how this indicator depends on geographical conditions and relative position of the city and the river.

The purpose of this study is to find out what has changed under the influence of digital transformation in the “physical” spatial structure of the retail sale/purchase process due to the emergence of a choice between online and offline “spaces” or environments, as well as how online commerce has changed the “physical” spatial principles of the organization of non-food retail in the Russian city on the example of St. Petersburg. The analysis of the principles of the placement of new e-commerce objects was carried out by comparison of various shopping models and the spatial-temporal systems formed by them, including specific objects (warehouses-shops, warehouses-fulfilment centers, order pick-up points and parcel lockers), features of interaction of retail actors and logistics flows in the city. In the geography of new types of retail facilities, two opposite trends are described: transfer of the trading function to non-trading premises and transfer of the non-trading retail function to retail premises. They form spatial competition with both traditional retail and a new hierarchical one - with office and warehouse types of business. The new trend of the trade infrastructure of durable goods to locate within walking distance from homes means the launch of a new type of competition for locations – with sellers of FMCG. The fact that in delivery the “last mile” logistics passes from the consumer to the seller / logistician means a fundamental change in the economic geography of the flows of goods. Instead of private spontaneous pedestrian flows, it forms new regulated small-tonnage types of “last mile” commercial freight transportation using both alternative (individual) modes of transport and trans port routes (sidewalks, pedestrian walkways, etc.). All this requires the development of a new urban regulation policy.

The results of seasonal studies of chemical composition of water coming from the residential area of Petrozavodsk to the Petrozavodsk Bay of the Onego Lake are presented. From the residential area of the city, 21.1 thousand tons of mineral salts per year, 8.3 tons of organic matter per year (in terms of COD), and 657.4 tons of nutrients per year enter the Petrozavodsk Bay with storm and drainage waters. With the runoff of the rivers Lososinka and Neglinka 10.1 thousand tons of mineral salts per year, 678.2 tons of nutrients (P, N, Si, Fe) per year enter the bay. In summer, compared with spring, the decrease in the concentration of sodium and chlorine in surface wastewater is observed in 70% of the samples, the increase in the concentration of sulfates is observed in 80% of samples. In winter, compared with autumn, an increase in the concentration of sodium and chlorine in surface wastewater is observed in 40% of the samples, and the content of sulfates decreases in 85% of the samples. Considering that the Petrozavodsk Bay serves as a source of centralized drinking water supply and an object of recreational and fishing activities, it is necessary to organize systems for treating surface wastewater.

Overabundant specific nutrient yield into the Baltic Sea results in its anthropogenic eutrophication. The Baltic Sea watershed countries including Russia aim to coordinate actions for protection of the sea marine environment. There is the environment protection committee (Helcom). The specific nutrient yields from watersheds of the Volkovka and Okhta Rivers of St. Petersburg were evaluated with usage of our methods. The specific nutrient yields were compared with ones calculated on the base of the numbers of inhabitants within the watersheds according to the Helcom methods. The research demonstrates that activity of the sanitary engineering and the state unitary enterprise (SUE) “Vodokanal of St. Petersburg” reduces nutrient load on the Baltic Sea from the watersheds in 19–45 times for total phosphorus and in 7–20 times for total nitrogen. The SUE “Vodokanal of St. Petersburg” is a conservational enterprise focused on the Baltic Sea environment protection.

This work discusses the specific features of riverine sediment inflow and its chemical composition to the Avachinsky Gulf of the Pacific Ocean. Based on the GloFAS-ERA5 reanalysis data, we assessed the hydrologic regime of the studied rivers. Further, the fingerprinting method was used to find the sediment transport pathways. In contrast, the sediment delivery to the Pacific Ocean with the Nalycheva River runoff is determined by the interpretation of turbidity plumes on Landsat satellite images. Our findings suggested the leading role of erosion processes on volcanic slopes in forming sediment yield associated with three primary sediment sources: the slopes of Avachinsky, Zhupanovsky and Kupol volcanoes. Our research pays special attention to the lahar consequences on the Zhupanovsky volcano slopes, which occurred in 2015. We supposed that this event had a short-term (within one year) impact on the sediment redistribution of the Nalycheva River estuary.

Three new species of the nudibranch family Onchidorididae are described applying the materials collected during expedition of the Russian Geographic Society “Eastern Bastion-Kurile Ridge 2021” from the coastal waters of the islands Urup and Chirpoy. Adalaria sergeii sp. nov., Adalaria neptuni sp. nov. и Onchidoris pavli sp. nov. are described on the basis of morphological data, including scanning electron microscopy. History of studies the nudibranch molluscs of Kurile Islands is briefly reviewed. The systematic position of new taxa is discussed and their importance for understanding the biogeographic patterns of the marine biota of the Arctic and North Pacific is highlighted.