Characteristic of Lower Don aquatic ecosystem in late autumn

Multidisciplinary studies were carried out in the Lower Don River in the low-water November of 2012. The studies showed relatively low concentrations of oil products (up to 2 MAC) and heavy metals (up to 1 MAC), which were likely due to the cessation of navigation in the river. However, copper concentration was found to be in excess of its MAC. The most polluted were found to be the port water areas of the cities of Volgodonsk, Ust’-Donetsk, and Semikarakorsk. The distribution of nutrients over streams is uneven: the Don water is poorer in nutrients than the waters of the Severskii Donets and the Manych are. Oxbows can serve as depots of organic matter, where it accumulates over longer periods than in the river. The residual manifestations of the summer–autumn blooming of blue-green algae, observed in shallows, the predominance of algae of divisions Cryptophyta and Bacillariophyta (typical representatives of winter planktonic algacenosis), and their low abundance suggest the transitional state of phytoplankton communities to autumn–winter season (pre-winter period). The species diversity and biomass of zooplankton were largest in the Don R. and lowest in the Severskii Donets R. The formation of zooplankton species composition shows the effect of the runoff from the Tsimlyanskoe Reservoir. An increase in the proportion of oligochaetes and invading species was recorded in the Don. The decrease in the diversity of benthos is attributed to natural factors, i.e., the decay of imago and thicket forms in autumn. The biomass of the soft (food) benthos is low because of the predominance of its small-size forms.     

Specific features of the hydrological regime of the Tsimlyansk Reservoir under climate changes in the Don basin

This study is a continuation of a cycle of studies into the effect of Atlantic climate on the hydrometeorological regime of European Russia. In this article, an attempt is made to analyze the effect of climate variations in the Atlantic on the Don basin and the hydrological regime of the Tsimlyansk Reservoir. A new composite index of heat transfer NAAII (North Atlantic Air Interaction Index) is suggested, the use of which enables the explanation of changes that have taken place in the Don basin. Evaporation was evaluated with the bathymetry of the Tsimlyansk Reservoir taken into account, and the water level of 32 m abs. was shown to be critical in the interaction between the reservoir and the atmosphere.     

Climate-induced changes in groundwater runoff in Don basin

The natural-climatic causes of changes in river runoff and seasonal recharge of groundwater in Don basin are considered. Joint analysis is made of changes in the statistical characteristics of the series of air temperature and precipitation, mean annual and dry-season-averaged runoff for both the entire observation period and of periods 1940–1969 and 1970–2000 with comparable durations. The presence of statistically reliable ascending trends in air temperature, precipitation, and dry-season (groundwater) runoff for period 1970–2005 is demonstrated. Climatic changes in Don basin also have their effect on the formation of extremely low water in small and medium rivers, including cases of zero runoff. Zoning of the territory by runoff formation conditions is carried out, and new estimates of natural groundwater resources in Don basin for period 1970–2000 are constructed. Appropriate maps are compiled.     

My journey to the center of the Earth: A tribute to Professor Donald V. Helmberger

It has been more than a year since Don passed away suddenly.Thinking about it still makes my heart hurt.I did not know Don Helmberger or any other famous geophy...     

Nutrient Loading of the Don and Kuban on the Ecosystem of the Sea of Azov

Hydrochemical data collected in field studies in the near-mouth area and delta of the Don R. (Aksay T.—the mouths of Don delta branches) in 2006–2015 are analyzed. The seasonal dynamics is demonstrated, and the average annual concentrations were evaluated for mineral, total dissolved, and total forms of nitrogen, phosphorus, silica; dissolved and particulate organic carbon; and total suspended solids in river water. The export of dissolved and particulate organic carbon and nutrients by the Don River into the Sea of Azov in the low-water period of 2007–2015 is evaluated. Retrospective analysis of nutrient export into the Sea of Azov with river runoff in the XX–early XXI century is given.     

In memory of Donald V. Helmberger

When I received the shocking news on August 13,2020 that our beloved Don passed away,I was deeply saddened.The feeling was worsened by the COVID-19 pandemic tha...     

Genotoxicity of Don River bottom sediments (2001–2007)

Data on genotoxicity of Don River bottom sediments in 2001–2007 are given. The regions of Lower Don are identified where genotoxin pollution has a chronic character are identified. The possible sources of their input are discussed.     

A grand master of seismology and mentoring

I joined Don Helmberger's group in the summer of 2008,after getting a Master's degree in China from Sidao Ni,another graduate student of Don's.I was very excite...     

Forecast of Water Consumption in the Russian Part of the Don Basin

Water Resources - Methodological approaches to water consumption forecasts are described. Demographic forecast and forecasts of the coefficient of water demand for regions in the Don basin are used...     

Priority Toxicants in Elements of Lower Don Ecosystem

Water Resources - The main sources of pollutants entering the Don R. ecosystem in its lower reaches are discussed. The principal sources are navigation, construction of new berths, dredging...     

Method of ecological standardization of the impact on water bodies that cannot be standardized by bioassay: Case study of water bodies in Don basin

The work is focused on studying the possibility to ecologically standardize the characteristics that are not concentrations of chemical substances, i.e., water abundance; water temperature; and pH, which does not belong to standardized characteristics. The initial data include the data of biological (water quality classes by characteristics of plankton, periphyton, and zoobenthos) and physicochemical monitoring in 1975–1991 in water bodies of the Lower Don, as well as data on fish catches and yield in the Lower Don. The values of ecologically tolerable levels are obtained for three factors, such that going above these levels causes the environmental ill-being of the appropriate biological indicator. Nonchemical impacts, represented by water abundance and temperature have almost no effect on the deterioration of ichthyological estimates of the state (the only exception is the correlation between water abundance and sabrefish catches). At the same time, planktonic and benthic estimates appear to be more sensitive indicators of water quality decline in all three factors under consideration. The pH exponent affects all ecological groupings of Don ecosystems. The strictest upper boundaries of ecologically tolerable levels of water abundance were recorded for the sabrefish catches. On the other hand, insufficient water abundance during spring and summer deteriorates the state of planktonic and benthic organisms.     

The Lost and the Found: Memories of Donald V. Helmberger

My first exposure to Don Helmberger's work was during a seismology class in my 2nd year in college where several students,including myself,were to present on Gr...     

A strange symbiosis: Seismic ray theory and Saturday touch football — Donald V. Helmberger as a graduate advisor

At the end of December of 1978 I was sitting in the office of Caltech Professor Don Helmberger,he was peering out his window towards the San Gabriel Mountains,s...     

How Donald V. Helmberger inspired me

I first met Don Helmberger when I visited Caltech in the spring of 1984 as a prospective graduate student.During that visit,I was immediately impressed by Don's...     

Variations in Methane Concentrations in the Water of the Don River and Taganrog Bay under the Effect of Natural Factors

Seasonal and diurnal variations in CH₄ concentration in the water of the Don River and Taganrog Bay are examined, and two maximums are recognized in the seasonal variations. The diurnal variations are shown to be affected by the meteorological conditions.     

My seismology journey with Donald V. Helmberger

My journey on the wiggles with Don started from February 2008,when I got an opportunity to visit the Caltech Seismolab as a visiting PhD student,which was made ...     

Short-Term Forecast of Water Levels in Don Mouth Area Using Hydrodynamic Simulation

Water Resources - The article presents the results of the test operation of a calculation–simulation complex (CSC) for level forecasting in a navigable branch in Don R. mouth area with daily...     

Pollution Degree of the Don River Water

Water Resources - The formation and distribution of river flow characteristics in the Don basin have been catholically analyzed, depending on the present-day climatic conditions in the central...     

从南通地形变等变化探讨地震短临预报的可能途径

1990年2月10日常熟——太仓5.l级地震前,南通等地形变等前兆手段异常明显。震例资料揭示,此次地震敏感部位的形变等前兆变化可区分出阶段性。据此作者探讨了形变短临地震预报的可能途径。     

Look again

Don Anderson argues that there is abundant evidence against the plume hypothesis, for an objective eye to consider.