The vertical structure of the water column according to optical data

Vertical profiles of the beam attenuation coefficient in different regions of the Barents Sea are analyzed. Data obtained show high space-time variability of seawater optical properties. In particular, the area affected by the river inflow (Pechora Sea) is distinguished. Very high values of the beam attenuation coefficient are observed in areas of coccolithophore blooms. There are a number of features associated with the flow of Atlantic waters into the Barents Sea. A close relationship between the seawater beam attenuation coefficient and total suspended matter concentration is shown. The corresponding regression equation is obtained.

Environmental stability of porcine respiratory coronavirus in aquatic environments

Coronaviruses (CoVs) are a family of viruses that are best known as the causative agents of human diseases like the common cold, Middle East Respiratory Syndrome (MERS), Severe Acute Respiratory Syndrome (SARS) and COVID-19. CoVs spread by human-to-human transmission via droplets or direct contact. There is, however, concern about potential waterborne transmission of SARS-CoV-2, the virus responsible for COVID-19, as it has been found in wastewater facilities and rivers. To date, little is known about the stability of SARS-CoV-2 or any other free coronavirus in aquatic environments. The inactivation of terrestrial CoVs in seawater is rarely studied. Here, we use a porcine respiratory coronavirus (PRCV) that is commonly found in animal husbandry as a surrogate to study the stability of CoVs in natural water. A series of experiments were conducted in which PRCV (strain 91V44) was added to filtered and unfiltered fresh- and saltwater taken from the river Scheldt and the North Sea. Virus titres were then measured by TCID50-assays using swine testicle cell cultures after various incubation times. The results show that viral inactivation of PRCV in filtered seawater can be rapid, with an observed 99% decline in the viral load after just two days, which may depend on temperature and the total suspended matter concentration. PRCV degraded much slower in filtered water from the river Scheldt, taking over 15 days to decline by 99%, which was somewhat faster than the PBS control treatment (T99 = 19.2 days). Overall, the results suggest that terrestrial CoVs are not likely to accumulate in marine environments. Studies into potential interactions with exudates (proteases, nucleases) from the microbial food web are, however, recommended.

Theoretical bases for determining the velocity and suspended matter concentration in the swirling zone beyond the transverse dam

Design dependencies to determine the velocity and concentration of suspended matter in the swirling zone beyond the transverse dam in the presence of the initial section of the jet are proposed in the article, using the main provisions of the theory of turbulent jets, the scheme of dividing the flow into hydraulic homogeneous zones: a weakly perturbed core, intense turbulent mixing and reverse currents. The distribution of velocities and concentration of suspended matter (turbidity) in the zone of intense turbulent mixing are affine and obey the theoretical Schlichting-Abramovich relationships; this was substantiated by laboratory and field studies. The equations of continuity and conservation of solid matter along the flow were used to solve the problem. To establish the adequacy of the dependencies obtained, a test problem was implemented in which the velocities in the core and the depth along the flow were assumed constant. The problem was implemented for the following contraction ratios of flow nc 0,1; 0.2; 0.3; 0.4; 0.5. Tabular and graphic dependencies obtained show that with all contraction ratios of flow, the relative backflow velocities first increase, and at the end of the swirling zone, they sharply decrease. The maximum is observed at the intersection of the outer boundary of the zone of intense turbulent mixing with the protected coast and reaches m = 0.317. Comparison of the calculation results with the experimental ones shows their qualitative and quantitative agreement. The relative concentration of suspended matter in reverse currents remains practically constant along the entire length of the swirling zone. It is close to unity for all contraction ratios of flow.

CALCULATION OF PARAMETER VALUES TO CHARACTERIZE THE CONSEQUENCES OF WORK ON THE DREDGING AND SUSPENDED MATTER DAMPING: ASSESSMENT BY MEANS OF THE SM-MODEL

The developed SM-model, describing the suspended matter concentrations in water environment, was used to assess the consequences of the works on dredging and dumping ground during the reconstruction and modernization of the water body area in the Pionersky Port (Kaliningrad region). The complex of recreated works includes 11 stages of the dredging works during which the various types of bottom sediments are extracted, some part of these sediments are transported outside the port water area and discharged into the marine underwater dump, while other their part are used for hydraulic engineering works in the port area. At the dredging and dumping the sediments, additional zones of water turbidity are formed (with a suspended matter concentration > 50 mg/L), its deposition causes the formation of a layer of sediments on the bottom. For each work stages, the technological data on the currents in the port water area are used for mathematical modeling and calculations of the amounts of various types of sediments extracted from the bottom, their redistribution over the sea area, the concentration of suspended matter in sea water, and the indicators (areas and volumes) of the emerging turbidity zones water due as a result of the construction works. Calculated data may be used to compile a report “Assessment of influence on the water environment state” (or AIWES) in the frame of these works.

INFLUENCE OF SUSPENDED FLUVIAL SEDIMENTS ON THE RIVER ICHTHYOCENE

Published data on direct and indirect impacts of suspended matter on freshwater fish are overviewed, both for short-term (hours) experiments and long-term (weeks and months) monitoring in natural conditions. Lethal or paralethal concentrations of the suspended matter are determined for 18 species from 8 families. Accumulation effect of the permanent concentration is observed for charr Salvelinus malma in the laboratory experiment. The most common fish families of the freshwater ichthyofauna in Russia are ranked by threshold of their sensitivity to suspended matter in the order: sturgeon and catfish (1000 mg/L) — carp (250 mg/L) — perch (100 mg/L) — salmon (10 mg/L, with paralethal concentration 25–35 mg/L). Fish mortality is estimated in dependence on the suspended matter concentration and time of exposure, by species. Environmental consequences of the suspended sediments impact are assessed for fish communities of the rivers of Kamchatka, the Lena River, and the Selenga River.

High Temporal Resolution Monitoring of Suspended Matter Changes from GOCI Measurements in Lake Taihu

The Tiaoxi River is the main source of water for Lake Taihu and can result in plumes in the lake after heavy precipitation events. These plumes have played a crucial role in the water quality changes within the lake. High temporal resolution GOCI (Geostationary Ocean Color Imager) data were used to study the spatial distribution of the total suspended matter concentration in Lake Taihu after heavy precipitation events in the Tiaoxi River Basin via an empirical model. The plumes were analyzed after two heavy precipitation events in 2011 and 2013 using 16 GOCI images, which indicated that the Tiaoxi River had a great influence on the spatial distributions of total suspended matter and algal blooms. It was concluded that the main factors affecting the plumes in the Tiaoxi River were precipitation intensity, runoff, and total suspended matter concentration. Human activity, such as sand excavation also played a crucial role in sediment discharge. The results of this study demonstrate that the visualization of GOCI data makes it possible to use remote sensing technology to continuously monitor an inland water environment on an hourly scale, which is of great significance for studying the diffusion and evolution of river plumes.