Математическое моделирование процессов эвтрофикации в мелководных водоемах на многопроцессорной вычислительной системе

The distribution and behavior of certain of trace elements in sea water is greatly affected by both physical, chemical and hydrometeorological conditions that are showed in the scientific works of prof. Yu.A. Fedorov with coauthors (1999-2015). Due to the shallow waters last factor is one of the dominant, during the different wind situation changes significantly the dynamics of water masses and interaction in the system “water – suspended matter – bottom sediments”.Therefore, the study of the behavior of the total iron in the water of the sea at different wind situation is relevant. The content of dissolved iron forms migration in The Sea of Azov water (open area) varies from 0.017 to 0.21 mg /dm3 (mean 0.053 mg /dm3) and in Taganrog Bay from 0.035 to 0.58 mg /dm3 (mean 0.11 mg /dm3) and it is not depending on weather conditions.The reduction in the overall iron concentration in the direction of the Taganrog Bay → The Sea of Azov (open area) is observed on average more than twice. The dissolved iron content exceeding TLV levels and their frequency of occurrence in the estuary, respectively, were higher compared with The Sea of Azov (open area).There is an increase in the overall iron concentration in the water of the Azov Sea on average 1.5 times during the storm conditions, due to the destruction of the structure of the upper layer and resuspension of bottom sediments, intensifying the transition of iron compounds in the solution.

Spatio-temporal changes in surface water quality and sediment phosphorus content of a large reservoir in Turkey

The basis for the 105th voyage of NIS “Professor vodyanitsky” was the Permission of the Ministry of education and science of the Russian Federation to conduct marine scientific research №DN-09 / 7I dated 19.09.2018 and №14-17/41 dated 30.03.2018, letter of the Ministry of education and science of the Russian Federation №14-858 dated 18.04.2018, license of the Federal service for Hydrometeorology and environmental monitoring of the Ministry of natural resources and ecology of the Russian Federation №R/2016/3020/100/L dated may 30, 2017 Scientific research in the voyage was carried out in accordance with the themes No. 0827-2018-0001 “Fundamental research of interaction processes in the ocean-atmosphere system, determining the regional space-time variability of the natural environment and climate”, No. 0827-2018-0002 “Development of operational Oceanology methods based on interdisciplinary studies of the processes of formation and evolution of the marine environment and mathematical modeling involving data of remote and contact measurements”, No. 0827-2018-0003 “ Fundamental research of Oceanological processes, state and evolution of the marine environment under the influence of natural and anthropogenic factors, on the basis of observation and modeling methods” and No. 0827- 2018-0004 “Complex interdisciplinary studies of Oceanological processes that determine the functioning and evolution of ecosystems of the coastal zones of the Black and Azov seas”, performed within the framework of the state task by the Federal state budgetary institution of science “ Marine hydrophysical Institute of the Russian Academy of Sciences), and also in accordance with the themes No. 0828-2018-0001 “Seismological and biogeochemical bases of homeostasis of marine ecosystems”, No. 0828-2018-0002 “Regularities of formation and anthropogenic transformation of biodiversity and bioresources of the Azov-black sea basin and other areas of The world ocean”, No. 0828-2018-0003 “ Functional, metabolic and Toxicological aspects of the existence of hydrobionts and their populations in biotopes with different physical and chemical regime», No. 0828-2018-0004 “Research of mechanisms of management of productive processes in biotechnological complexes for the purpose of development of scientific bases of reception of biologically active substances and technical products of marine Genesis” and No. 0828-2018-0005 “the Structural and functional organization, productivity and stability of marine pelagic ecosystems” performed within the state task by Federal state budgetary institution of science “ Institute of marine biological researches. A. O. Kovalevsky Russian Academy of Sciences” (INSTITUTE IMBI). Works of employees of the Federal state budgetary institution of science “ Institute of Oceanology. P. P. Shirshova RAS “(IO RAS) were carried out within the framework of the state task of the Institute, as well as the project of RNF No. 14-27-00114-P “ Sedimentary-biogeochemical studies of the seas of the European part of Russia (scattered sediment, bottom sediments, diagenesis)”. The interaction of Geosphere, the flow of matter and energy” under the guidance of academician A. P. Lisitsyn.

The use of mechanistic descriptions of algal growth and zooplankton grazing in an estuarine eutrophication model

The paper covers problems of solving tasks of water ecology on multiprocessor computer system (MCS). We proposed a new model of biological rehabilitation of shallow waters in view the factors that have a significant influence on the water quality. Its discretization was performed with using the balance method and the implicit scheme with central differences. The proposed numerical method for the solution of the model problem is most common and is suitable to the study of hydrobiological processes occurring in shallow waters. Since it allows to correctly design computational algorithms on the boundary between the integration domain and environments. One of the objectives of the work is reducing the calculation time and saving the accuracy of the results of solving problem of biological rehabilitation of shallow waters by using a multiprocessor computer system. Two algorithms have been developed in the implementation of the parallel algorithm for solving problem on the MCS for the distribution of data between the processors. There is the algorithm on the basis of the k-means method, based on the minimization of the functional of the total sample variance of scatter elements about the center of gravity of the subdomains, which allows increasing the efficiency of the parallel algorithm of the hydrobiology problem of shallow water. Using the MCS can significantly reduce the calculation time while saving the accuracy of the solution. The latter fact provides the fast and qualitative interpretation of hydrobiological data.

We present here results that demonstrate the potential of the recently launched Ocean and Land Colour Instrument (OLCI) onboard the satellite Sentinel-3A to deliver accurate estimates of chlorophyll-a (chl-a) concentration in coastal waters using reflectances in the red and near-infrared (NIR) spectral regions. Two-band and three-band NIR-red models that were previously used for data from the MEdium Resolution Imaging Spectrometer (MERIS) were applied to OLCI data from the Sea of Azov and the Taganrog Bay, Russia. Atmospherically corrected reflectance data from OLCI were compared to in situ reflectance data collected concurrently with a field spectrometer. Results show that the default atmospheric correction procedure currently applied to OLCI data performs well in preserving the spectral shape of chl-a-specific reflectance features in the red and NIR regions. Similar to what was achieved with MERIS data, the NIR-red models yield accurate estimates of chl-a concentration, with accuracies on the order of 90%, though the parameters of the NIR-red algorithms based on OLCI data are slightly different from what was obtained with MERIS data. More data, from various geographical locations, need to be analyzed to establish robust NIR-red algorithms for OLCI data.

Based on the actual and climatic oceanological data, the notions on composition of the field of the dissolved organic matter content in the Taganrog Bay, from the Don River mouth to the Azov Sea adjacent water areas are obtained. The features of the natural marginal filter of the Don mouth and the runoff waters in the bay are considered. Significant heterogeneity in the field of the considered characteristic (its concentration exceeds the natural standard in the Don mouth) is revealed, that can probably be a consequence of the dissolved organic matter anthropogenic sources, in other words, waste waters from the settlements. The pronounced frontal section, i. e. a natural marginal filter, was revealed in the field of the dissolved organic matter concentration. It was located along the maritime part of the Don River mouth within the narrow shore strip (its width is approximately 0.5-1.0 miles). Across this natural marginal filter, the dissolved organic matter concentration reduced abruptly towards the open sea. Up to 50% of the dissolved organic matter brought to the marine part of the Don mouth remained on the filter. It is revealed that salinity and the dissolved organic matter content in the marginal filter area are closely bound by the backward correlation dependence with the coefficient -0.87. It is shown that the dissolved organic matter concentration in the Taganrog Bay decreases in the area between the marginal filter and the runoff front from 20 to 3 mg/l, and complete transformation of the bay waters saturated with the dissolved organic matter is observed in the runoff front which, in course of the major part of a year, is located at the bay outlet. Seaward off the front external boundary (isohaline 10 PSU), the fields of salinity and dissolved organic matter content are characterized by spatial homogeneity with the 10-13 PSU salinity and the dissolved organic matter concentration 1-3 mg/l which are typical of the Azov Sea open water areas. It is found that weakly pronounced vertical stratification of the field of the dissolved organic matter concentration is peculiar to all the studied water areas.

The paper covers the development and research of mathematical models of the algal bloom, causing suffocations in shallow waters on the basis of modern information technologies and computational methods, by which the accuracy of predictive modeling of the ecology situation of coastal systems is increased. Developed model takes into account the follows: the water transport; microturbulent diffusion; gravitational sedimentation of pollutants and plankton; nonlinear interaction of plankton populations; biogenic, temperature and oxygen regimes; influence of salinity. The computational accuracy is significantly increased and computational time is decreased at using schemes of high order of accuracy for discretization of the model. The practical significance is the software implementation of the proposed model, the limits and prospects of it practical use are defined. Experimental software was developed based on multiprocessor computer system and intended for mathematical modeling of possible progress scenarios of shallow waters ecosystems on the example of the Azov Sea in the case of suffocation. We used decomposition methods of grid domains in parallel implementation for computationally laborious convection-diffusion problems, taking into account the architecture and parameters of multiprocessor computer system. The advantage of the developed software is also the use of hydrodynamical model including the motion equations in the three coordinate directions.

Fil: Vilches, Carolina. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina. Universidad Nacional de Lujan. Instituto de Ecologia y Desarrollo Sustentable. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Parque Centenario. Instituto de Ecologia y Desarrollo Sustentable; Argentina

Diatoms are powerful bioindicators, as each species has a specific tolerance for environmental variables, they are abundant in aquatic ecosystems and they respond rapidly to change. The use of diatoms as bioindicators is widespread especially in streams, rivers and natural lakes and is increasing in reservoirs. Typically, diatoms utilised in streams and rivers for biomonitoring consist of living benthic communities attached to rocks, while in lakes and reservoirs diatoms collected from the sediments consist of senescent planktonic diatom that have settled out of the water column. The development of diatoms as indicators in reservoirs can be problematic due to the complex hydrology and higher rates of sedimentation associated with these systems. Despite these challenges the use of diatoms in reservoir environments to develop transfer functions to infer historical changes in water quality is increasing. The development of regional datasets is important, as using indicators or transfer functions that have been developed in other areas to quantify changes in water quality does not provide accurate results. The aim of this thesis was to develop diatoms as bioindicators of water quality in freshwater reservoirs of subtropical south east Queensland (SEQ), to complement the traditional water quality monitoring across different sites. This will provide understanding of environmental drivers of diatom assemblages in this region. The diatom assemblages of reservoirs in this region have not been investigated to date and this study will provide the first investigation into their biological diversity and the water quality histories of the reservoirs. This study was undertaken in drinking water reservoirs of subtropical south east Queensland, Australia. Spatial variability of the sediment surface diatom assemblage was investigated in the Lake Wivenhoe, the largest reservoir of the region which supplies over two million people with drinking water. The diatom assemblage of surface sediments was found to vary spatially within a reservoir and aligned with zonation that is typical of reservoir environment, lacustrine, transition and riverine. Three groups of diatoms characterised the reservoir, taxa reported as cosmopolitan were found throughout, higher abundances of planktonic taxa were observed in the lacustrine zone and benthic taxa were reported in the riverine zone. Sediment samples were collected from 15 reservoirs in south east Queensland. The diatom assemblage and corresponding water quality parameters from each site were used to develop transfer functions specific for the region. Robust models were developed using weighted averaging partial least squares for conductivity and total phosphorus. The optimum and tolerances of these parameters are reported for 116 diatom taxa. Early in 2011, the largest rainfall on record took place in the Wivenhoe dam catchment which resulted in an extreme inflow into the reservoir. One core had been taken in October 2010 to determine historic changes in the diatom assemblage. Following the 2011 event another core was collected to assess the effect an extreme inflow had on the sediment record of the reservoir. Analysis of the cores revealed the impact that a high magnitude event has on the sediment record of a reservoir, with both the diatom assemblage and 210Pb profiles impacted. The diatom assemblage and 210Pb profile prior to the extreme inflow would have been insightful for reconstructing past water quality conditions and estimating sedimentation rates. However, following the inflow, diatom and 210Pb analysis should be undertaken carefully to account for the disruption to the upper sections of the sediment record caused by the extreme inflow. The construction of a new dam, Wyaralong, in SEQ provided the unique opportunity to assess the diatom assemblage as the environment changed from a stream to reservoir. Construction was completed in December 2010 and the reservoir filled within a month. A clear shift in the diatom assemblage from benthic to planktonic following infilling is seen. Additionally the collection and assessment of the sediment core provides an estimation of the sedimentation rate in this reservoir. Sediment diatom communities of freshwater reservoirs in south east Queensland are suitable for use as bioindicators of water quality parameters, in particular conductivity and total phosphorus. This work also provides a low cost estimation for rates of sedimentation. The transfer functions developed in this study provide a powerful and cost effective tool or inferring historic water quality, to be used cautiously in reservoirs known to have been impacted by large inflow events, and provide a baseline for future work using sediment surface diatom assemblages.

Factor analysis was used to identify the processes responsible for the changes in water quality in a stratified wastewater reservoir. These reservoirs are well suited to study hypertrophic conditions. In the epilimnion, the main source of variablility was the external loading due to variations in wastewater inputs and water level (volume) of the reservoir. The second source was the seasonal climatic changes affecting photosynthesis. The third source was differences between night and day processes affecting REDOX potential. In the hypolimnion, the main source of variability was organic loading but due to both external loading (wastewater inputs) and internal loading (compounds released from the sediments). The second source was related to the input of chlorophyll into the hypolimnion, which were external (entry of chlorophyll rich inflow from a waste stabilization pond) and/or internal (input of chlorophyll from upper layers due to water column mixing).

A mathematical model has been developed as an idealized formulation to understand the eutrophication status in Masan Bay. The model predictions were in general agreement with field data in simulating the global growth and decay of phytoplankton. The WASPS model was used for investigation of phytoplakton-nutrient dynamics as well as the comparison with both mathematical and numerical models developed here. The water quality simulation with fine resolution has been performed by a coupled hydrodynamic, transport, and eutrophication model. The hydrodynamic component simulates the main tidally-driven advective flows throughout the Masan Bay and the transport component of the model simulates the movement of dissoved materials in response to the tidally-driven advective and dispersive processes coupled with freshwater from 12 streams flowing into Masan Bay. The transport was determined by a new hybrid method [1] which takes forward-tracking for advection and finite difference approximation for diffusion. All submodels including eutrophication model operate on the same grid. Results are compared with field data obtained in 1995 and they show an encouraging degree of similarity.

The quality of the drinking water source reservoirs has always been a research hotspot. However, few have studies focused on the water quality of reservoirs over a relatively long period with time series analysis. In this paper, based on water quality and hydrological data from 2010 to 2020, considering 8 water quality parameters, CCME-WQI with time series analysis was used to explore the interannual and seasonal changes in water quality in the Weishui Reservoir. Furthermore, the main factors affecting water quality were discussed through correlation analysis. The ARIMA model is used to predict water quality in the future. The results show that the water quality was seriously polluted from 2012 to 2013. After 2018, the water quality gradually improved and stabilized. In addition, the water quality is affected by inflow, showing the characteristics of poor water quality in summer and winter. The key parameters affecting water quality are TN and TP, which are almost 2 times higher than the grade II standard of water quality standard. Through the ARIMA model, it is predicted that CCME-WQI is maintained at 80.46 indicating that the water quality will be stable in the future.

A novel method for assessing water quality status using MODIS images: A case study of large lakes and reservoirs in China

The effect of farming practices on water quality has been under increased scrutiny in Iowa. Overall water quality in Iowa has improved over the past 30 years, but the number of impaired water bodies in the state is not decreasing. Achieving sustainable watershed management can result in economic benefits to farmers and social benefits to the community, while preserving the ecological integrity of the aquatic ecosystem; it is through our research that we hope to elucidate better methods in order to meet this challenge. The Iowa River has been designated as an impaired water body since 1998 by the Iowa Department of Natural Resources. Coralville Reservoir, a mainstream impoundment of the Iowa River, is classified as a eutrophic lake and an impaired water body due to high bacterial concentrations. It is the primary drinking water source for Iowa City, Iowa. The Coralville Reservoir Water Quality Project was started in 1964 with the original objective of measuring the water quality of the river and reservoir. Continuous monitoring has yielded a data set of over 10,000 data points, allowing the detection of long-term water quality changes and providing insights into the natural and anthropogenic factors responsible for the changes. Preliminary analysis of the data set shows that the amount of nitrate-nitrogen in the reservoir has an increasing trend over a 30-year time span (1972-2003), while the amount of orthophosphate shows a gradual decreasing trend. Total suspended solids have decreased over the same period. Determination of the effectiveness of Best Management Practices (BMPs) on the available sediment and nutrient load by correlating historical and current rates of sediment loading to precipitation events, land use changes, agricultural practices and suburban development will be reported.