Numerical simulation of water exchange processes in Lake Baikal

A review of the study of water exchange processes in Lake Baikal is given. The major attention is given to the mathematical simulation of the processes of density stratification processes and the effect of different hydrophysical factors on water exchange processes, in particular, the formation of thermobar and vertical circulations in the lake.     

Water Exchange between Bed Depressions in Baikal

Published results of studies and calculations based on data on the salinity of river and lake waters are used to assess the resulting horizontal water exchange between bed depressions in Baikal. The role of this process in the redistribution of nutrients in the lake is demonstrated using dissolved Si as an example.     

Lake Water Resources in the Asian Part of the Russian Federation

Water resources of lakes with natural and regulated hydrological regime are evaluated, and estimates are given to the water resources of artificial water bodies in three federal districts in the Asian part of RF (Ural, Siberian, and Far-Eastern) and the constituent entities of the Federation they contain. The estimates were made by a new procedure, incorporating up-to-date satellite data and functions of Google Earth project. In the Asian part of RF, ~3140000 natural water bodies were analyzed, including ~1170000 lakes >1 ha in area and ~6000 artificial water bodies. Lake water resources in the Asian part of RF amount to 24537 km³, of which ~96% are contained in Lake Baikal. Other 638 km³ are contained in artificial water bodies.     

Interaction between Streams and Lower Surfaces of Ice Cover

The structure of the boundary layer is studied at the lower ice surface in Lake Baikal and the Moskva River. The Rossby parameter is used to compare the roughness of the lower ice surfaces in these water bodies. An attempt is made to estimate the thickness of the boundary layers under study.     

Variations of under-ice currents in Southern Baikal by data of 2012–2016

New data on under-ice currents in Lake Baikal have been obtained with the use of high-accuracy instruments. The obtained data were used to analyze the time and space variations of under-ice currents, to calculate the coefficients of horizontal turbulent exchange and turbulent energy dissipation rates, and to derive spectral estimates of the obtained results. The estimated structures of the under-ice boundary layer near the Angara opening and far from it (up to 5 km) were compared.     

Dynamic-stochastical modeling of long-term fluctuations in Lake Baykal levels and Angara River runoff

The results of modeling of the long-term fluctuations in Lake Baikal levels and Angara River runoff are presented. The dynamic-stochastical model was developed and used to obtain analytical relationships between the statistic characteristics of the Baikal levels fluctuations and the parameters of forcing processes, including water inflow into the lake and the effective evaporation from its surface. The parameter λ determining the inertia of the Baikal levels fluctuations, decreased by about three times after Irkutsk Reservoir filling, resulting in an increase in the variance of the lake levels fluctuations. The dependence of variances of the Baikal levels fluctuations and Angara runoff on parameter λ was studied. It is shown that the decreasing in the variance of the Baikal levels fluctuations corresponds to increasing in the variance of Angara river runoff and vice versa. The results of numerical modeling of Baikal levels fluctuations show that water withdrawal from inflow into the lake has an adverse effect on Angara runoff regime.     

Allochthonous and autochthonous organic matter in surface waters in Karelia

A relationship between indirect chemical indices of organic matter content of surface waters and light absorption in the visible and ultraviolet ranges is discussed. The allochthonous and autochthonous types of organic matter are found to essentially differ in the rate of light absorption. Techniques are proposed for the calculation of the concentrations of allochthonous and autochthonous organic matter by the integral rate of light consumption in the visible region and the bichromate oxidability of water, as well as by three indirect indices: chemical oxygen demand, permanganate oxidability, and water color index. The mean concentrations of allochthonous and autochthonous organic matter in large lakes (Ladoga, Onega, and Baikal) and in rivers and smaller water bodies in Karelia (>300 water objects) are analyzed. Allochthonous organic matter was found to predominate in most surface waters of Karelia (>80%), while allochthonous organic matter predominates only in lakes with a small specific catchment area (supposedly, <5) and in highly eutrophic lakes.     

Gesetzmäßigkeiten des Sauerstoffaustausches zwischen Gewässer und Atmosphäre im Flußmündungsgebiet

Meteorological conditions, biochemical processes in water bodies and anthropogenic pressure of a region are the main factors to determine the atmosphere water-body gas exchange. Research on oxygen outflows in the Dnjepr estuary region has shown that though gas exchange with atmosphere permanently exists its intensity varies throughout a day, vegetation period, year. The process of evasion is the most active in the flood plain pools of the river. Oxygen exchange between the atmosphere and a river is to be determined with physical characteristics of water outflow and with the anthropogenic influence. Oxygen absorption from the atmosphere is dominating for the liman water area in spite of differences between its parts. The obtained results have shown that gas exchange between river estuary pools and the atmosphere is of great importance for the oxygen balance of these pools.     

Assessment of runoff,water and sediment quality in the Selenga River basin aided by a web-based geoservice

The Selenga River is the main artery feeding Lake Baikal. It has a catchment of ~450000 km² in the boundary region between Northern Mongolia and Southern Siberia. Climate, land use and dynamic socioeconomic changes go along with rising water abstractions and contaminant loads originating from mining sites and urban wastewater. In the future, these pressures might have negative impacts on the ecosystems of Lake Baikal and the Selenga River Delta, which is an important wetland region in itself and forms the last geobiochemical barrier before the Selenga drains into Lake Baikal. The following study aims to assess current trends in hydrology and water quality in the Selenga-Baikal basin, identify their drivers and to set up models (WaterGAP3 framework and ECOMAG) for the prediction of future changes. Of particular relevance for hydrological and water quality changes in the recent past were climate and land use trends as well as contaminant influx from mining areas and urban settlements. In the near future, additional hydrological modifications due to the construction of dams and abstractions/water diversions from the Selenga’s Mongolian tributaries could lead to additional alterations.     

自然水体中悬浮物对反硝化影响的研究进展

悬浮物在自然水体（池塘、河流、湖泊等）中普遍存在,相较于上覆水,是微生物更为倾向的附着载体。相较于沉积物,更易获取硝酸盐,是水体反硝化发生的热点微区。悬浮物在水体中经历一系列碰撞、絮凝、溶解、离子交换、吸附解吸等物理化学过程,从而会引起颗粒物粒径、营养盐浓度等发生变化;悬浮物的沉降和再悬浮过程也会引起上覆水和沉积物之间的物质交换,并在好氧缺氧过渡过程中对氮转化造成影响,从而直接或者间接影响水体反硝化速率。本文概括了国内外关于悬浮物影响水体反硝化的研究进展和热点,总结了不同浓度、粒径、组成和种类的悬浮物对反硝化作用的影响,从溶解氧、功能微生物、无机氮、有机碳等环境因素重点归纳了悬浮物影响反硝化的过程,比较和分析了悬浮物反硝化的测定方法。结合当前悬浮物反硝化研究现状,建议未来可以从新兴污染物悬浮物、机理模型、测定方法等方面展开深入研究。     

C.—W. M. O.—O. M. M.

Abstract

The intrusion of seawater in a tidal river is treated as a diffusion problem, characterized by a coefficient of longitudinal diffusivity.

In order to analyse the longitudinal diffusivity, a mathematical model is set up, consisting of two bodies of water, either one besides the other or one on top of the other. The two bodies are assumed to move relatively to each other, as a secondary effect of the tidal flow. It is moreover assumed that there is turbulent exchange of salt between the bodies.

It is demonstrated that the diffusion of salt into the river is greatest for an optimum value of the coefficient of exchange between the two bodies.

Exchange weaker or stronger than this optimum both diminish the salt intrusion.

The theory is applied to the Rotterdam Waterway, for which estimates of the exchange are made. Estimation of the reduction of the turbulence by stratification and hence of the vertical exchange, shows that the observed strong intrusion is explainable.

Intensified vertical mixing, for instance as provoked by compressed air, need not always result in less intrusion, and hence should be considered carefully.     

Diurnal Variations in the Rate of Gas Exchange between Lake Baikal and the Atmosphere

The diurnal course of gas exchange between Lake Baikal and the atmosphere during the summer warming up is calculated using the data of continuous 102-hour observations in August 2000 and the published materials of individual diurnal measurements of the dissolved gases concentrations made in different years. The diurnal course of the rate of gas exchange in both the coastal and open parts of the lake is found to be due to the fact that slow gas-exchange processes fail to compensate fast changes in the partial pressures of gases dissolved in the upper water layer. The changes are associated with the diurnal dynamics of the hydrometeorological conditions and the intensity of the production–destruction processes. It is found that under light winds, the contribution of biological factors to the formation of short-period variations in the CO₂ and O₂ fluxes through the lake water surface makes about 80% and that of abiotic factors, 20%. Considerable aperiodic changes in the diurnal course of hydrometeorological conditions are found to essentially distort the normal diurnal course of the gas-exchange processes.     

贝加尔湖的污染与富营养化

The long term systematic investigations of ion composition components (bicarbonates, chlorides, sulphates, magnesium, calcium, sodium, potassium) and trophic status components (suspension, chlorophyll-a, mineral and organic forms phosphorus and nitrogen, carbon, silica) of water from the lake proper, its tributaries and atmospheric precipitation, which make up the main share of substance supply in to the lake, as well as the Angara river, being the source of substance discharge allowed the lake recent state to be evaluated in terms of both chemical pollution and possible eutrophication of its water. The similar (in terms of river runojf) periods of 50-ies and 80-ies have been compared. It was revealed that as a result of industrial activity 409 thousand tons of mineral substances (27.2 thousand tons of chlorides, 162 thousand tons of sulphates and over 200 thousand tons of organic substances) are supplied in the lake annually. The supply of substances of the anthropogenic origin is higher for the South Baikal than that for the North and Middle Baikal (the sum of mineral substances in 3.6 times; sulphates in 5 times, organic substances, including hydrocarbons in 7 times).The absence of abundant phytoplankton in the period studied when the ratio of silica to phosphorus is optimum (over 100), as well as a revers correlation between winter nitrogen content and spring of chlorophyll-a concentration in the Baikal water and revers dependence between the suspension and chlorophyll-a along the Selenga river valley lead to the conclusion that Baikal water contains toxicants. It is verified by the presence of polychlorbiphenyls (PCB), poly-chlordibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) for the whole food web with the maximum PCDD/PCDF (TEQ to 175 P g · g^-1) concentration in the seal blubber. The levels are comparable with those reported for ringed seal (phoca hispida), living in the Baltic sea and Bar-row Strait Inlet in the Canadian Arctic.     

Hydrogen and oxygen isotope ratios in the waters of the Ngawha hydrothermal area,North Auckland

The ratios of D/H and O¹⁸/O¹⁶ in natural waters from streams, boreholes, soda springs, hot pools, ponds and larger bodies of water in the Ngawha hydrothermal area were determined. The results are considered in relation to the isotopic changes known to occur in water subjected to evaporation. Where applicable chemical and other work was also considered. It is assumed that stream water isotope composition is the mean value for the isotopic composition of meteoric waters. Measurements on waters taken from boreholes drilled to 65 feet and 350 feet and from the other water sources mentioned, indicate that they were of meteoric origin as judged by stream isotope composition. The waters from the soda springs appeared to be isotopically the same as the stream water, a finding consistent with the absence of evaporative surface. These borehole waters were similar but slightly different in O¹⁸ due probably to exchange between rock and water. Heavy isotope enrichment of the ponds and larger bodies of water appeared to be due to non-equilibrium evaporation at ambient temperature. The hot pools in the Ngawha springs area proper were enriched in the heavier isotopes probably due to non-equilibrium evaporation at the usual hot pool temperature of about 40°C and also to exchange of O¹⁸ between water and rock. The water from a further borehole drilled to approximately 2,000 feet appeared also to be of meteoric origin but was changed in O¹⁸ content to an extent consistent with the assumption that oxygen isotope exchange with rock had taken place at approximately 230°C. The results are used to illustrate possibilities for the use of oxygen and hydrogen isotope measurements in hydrothermal investigations.     

Assessing the state of water masses of the Southern Baikal in the zone of influence of Baikal PPM by many-year microbiological characteristics

Results of many-year (1990–2009) microbiological studies of waters in different parts of Southern Baikal subject to different anthropogenic load are presented. Long-term observation series made it possible to establish tendencies in variations of the structure and functional activity of microbiocenoses as the result of natural evolution and anthropogenic impact. The obtained microbiological data characterizes water quality and the level of technogenic disturbances near Baikal Pulp-and-Paper Mill. Water quality assessment by sanitary-bacteriological characteristics suggests that the water area near the discharge site of effluents from Baikal PPM chronically experiences bacterial pollution. No significant changes in the technogenic stress on Southern Baikal ecosystem have taken place since the 1990s.     

Relationships between Water Flow and Dissolved Solids Discharge in the Major Tributaries of Lake Baikal

Data of long-term observations of water and hydrochemical regimes were used to characterize relationships between water flow and dissolved solids discharge in the three major tributaries of Lake Baikal, which account for about two-thirds of the total water inflow into the lake. The total dissolved solids content (TDS) of these rivers' water and the concentrations of the principal ions are classified taking into account the relationships between the sources of alimentation.     

Episodes of high correlation between annual rates of earthquakes: The Baikal Rift Zone

Correlation analysis techniques were used to study variations in the annual rates N of completely reported earthquakes with energy class K ≥ 8 that occurred from 1964 to 2001 in the Baikal Rift Zone (BRZ), in three subregions within that zone, and in six areas. This correlation analysis of samples of annual rates of earthquakes N with different observation periods revealed two statistically significant episodes of short-lived synchronization between the seismic processes in the BRZ, in the late 1960s and in the late 1970s to the early 1980s. The 1970–1980 episode stands out because of its duration and the highest correlation level; this makes it the dominant phenomenon in the Baikal Rift seismicity synchronization. The observed synchronization episodes between annual rates of earthquakes show that the seismic process was activated at about the same time in different subregions of the BRZ, thus producing short-lived coherent increases in seismicity rates.     

Hydrochemical and microbiological characteristics of the Gusino-Ubukunskaya group of water bodies

Results of hydrochemical and microbiological studies of five largest water bodies belonging to the Gusino-Ubukunskaya group are presented. Present-day environmental state of the ecosystem subject to anthropogenic load is described. The possibility of using water quality parameters of the investigated lakes as indicators of the degree of contamination of waters flowing into the Baikal Lake is shown.Translated from Vodnye Resursy, Vol. 32, No. 1, 2005, pp. 79–84.Original Russian Text Copyright © 2005 by Khakhinov, Namsaraev, Ulzetueva, Barkhutova, Abidueva, Banzaraktsaeva.     

Level regime regulation in Lake Baikal

The problem of level regime regulation in Lake Baikal under the contradictory conditions of the legislation now in force in RF is considered. The concepts analyzed in the study include the normal and extreme water abundance, the frequency of the useful inflow, and the factors that influence the level regime. The results of simulation of the level regimes under normal, extremely low, and extremely high water content are given. The possible changes in the level variation range in Baikal are estimated at different water content with technical and socioeconomic limitations taken into account.     

Specific features of cold bottom intrusion in Baikal according to observations in 1993–2009

The specific features of cold bottom intrusion in Baikal are considered based on the results of observations of 1993–2009. It is shown that the intrusion-related renewal of bottom water takes place not regularly and not simultaneously in different hollows. Its maximums were recorded in Southern Baikal in 1997 and 2007, in Middle Baikal in 1995, 2006, and 2009, and in Northern Baikal in 1997 and 2009. In these years, the volume of cold bottom layer in some hollows reached 200–470 km³ and its total cooling reached −20 to −60 MJ 10⁹. Cold intrusions were more frequent and had greater effect on the bottom layer in Southern Baikal than in other parts of the lake. The intrusions, especially in the years of their active development, are shown to cause water cooling in both the bottom layer and the major part of the deep-water zone of all hollows.