New challenges towards ecological management of Paliastomi Lake will signicantly improve local environment with far-going global consequences

The publication is addressing the problems of pollution from agricultural sources; municipal wastewater and industry in line with the bacterial pollution caused by migratory waterfowl of Paliastomi Lake that is an internationally recognized habitat, wintery and transit area of the birds and an important tourism site. It reviews: the current state of the environment of Paliastomi Lake at the moment of the chemical and microbiological research and mathematical simulation modeling of possible dissemination of polluting chemicals and bacterial pathogens; pollution by nutrient-rich water causing large blooms of algae and aquatic plants that in its turn leaves little oxygen for fish and other aquatic animals, resulting in the eutrophication followed by suffocation of aquatic life. the integration of the two-dimensional flow dynamics of THE lake dynamics and passive impedance in the water area using a modern high-resolution numerical plan. During the integration, the method of visualizing the results was applied.


Introduction
The Greek geographer, philosopher, and historian Strabo (64 or 63 mention Paliastomi Lake: "The Phasisi (river Rioni) flows into the Ponto" (Black Sea). Colchis Commercial is a city on the Phasisi River with the sam records the existence of a lake at the Rioni River's mouth language: Palaeo -old; Stoma Paliastomi Lake ( Figure 1) Convention, and is part of the Kolkheti National Park center area of the Black Sea coastal alluvial plain, in the administrative reg well as the territory of the city of Poti (55,500 ha including the marine part). range of relict and unique flora and wildlife. Waterfowl of many species winter at the site [2]. The area and its biodiversity are protected by the international conventions (Biodiversity, Ramsar, Bonn, Black Sea) and the national legislation Its surface area is 17.3 km² and its mean depth is 2.6 m (See The Greek geographer, philosopher, and historian Strabo (64 or 63 BC mention Paliastomi Lake: "The Phasisi (river Rioni) flows into the Ponto" (Black Sea). Colchis Commercial is a city on the Phasisi River with the same name. Agathias Scholasticus (ca. 532 records the existence of a lake at the Rioni River's mouth. The meaning of: "Paliastomi derives from Greek old; Stoma -pore, hollow [1]. ( Figure 1) is a protected area of international importance, according to the Ramsar Convention, and is part of the Kolkheti National Park (Figure 2). It encompasses a total of 33,710 acres in the center area of the Black Sea coastal alluvial plain, in the administrative regions of Khobi and Lachkhuti, as well as the territory of the city of Poti (55,500 ha including the marine part). The site is home to a diverse range of relict and unique flora and wildlife. Waterfowl of many species winter at the site [2]. The area and its biodiversity are protected by the international conventions (Biodiversity, Ramsar, Bonn, Black Sea) and the national legislation harmonized with EU aquis in accordance with km² and its mean depth is 2.6 m (See Figure 3).
The impact of ecological factors caused Paliastomi lake salination with associated changes in water crease in composition of the lake biodiversity (the number of fish species decreased 4 BC-1-c. AD 24) was the first to mention Paliastomi Lake: "The Phasisi (river Rioni) flows into the Ponto" (Black Sea). Colchis Commercial e name. Agathias Scholasticus (ca. 532-580), a Greek historian, The meaning of: "Paliastomi derives from Greek otected area of international importance, according to the Ramsar It encompasses a total of 33,710 acres in the ions of Khobi and Lachkhuti, as The site is home to a diverse range of relict and unique flora and wildlife. Waterfowl of many species winter at the site [2].

Kolkheti National Park
The area and its biodiversity are protected by the international conventions (Biodiversity, Ramsar, harmonized with EU aquis in accordance with EU-Georgia AA. alination with associated changes in water crease in composition of the lake biodiversity (the number of fish species decreased 5 The Lake is fed by rain water and tributaries. High water levels are common in spring, summer and fall, while in winter the water level is low. The water is warm in July and August (25.1 0 C) and is cold in winter (5.2 0 C). Due to strong winds, homothermia is quite frequent on the Lake (see Figure 4).
Paliastomi Lake is separated from the Sea by the 300-400-meter-wide and 2-meter-high sand-bar. Sedimentation and extensive vegetation development plague the lake. Rivers are controlled by flood banks in wetter locations. The rivers (Pichora, Tkhorikna, and others) and lakes (Paliastomi, Imnati, Maltakva, and others) receive water from a large watershed, and water levels in marshes, lakes, and rivers range from 0.2 to 0.7 meters, 0.5 to 3 meters, and 1 to 21 meters. Paliastomi Lake was a freshwater lake until 1924, with water draining into the Kaparchina River, which begins on the lake's northwest shore. Because the River Kaparchina's capacity was insufficient to adequately drain all of the floodwater from the Lake, the level of Paliastomi Lake (see Figure 1) increased swiftly during the heavy rain and flooded about 40 km2 of the area, incl.
To protect Poti from periodic flooding, in 1924 a canal was built to connect the southwestern part of the Lake with the Sea After some time, powerful storms eroded the canal and it was replaced by a strait, 1.5 km long, 140-150 m wide and 3-4 m deep watercourse. Sea water freely enters the through this strait during the heavy storms, and this has salinized the Lake: before the strait was excavated, the lake's salinity used to be 1%; now it's 12-13% [3]. The amount of annual atmospheric precipitation in the Kolkheti lowlands ranges from 1200-2800 mm, and the modulus of groundwater runoff pressure is 4 l / s from 1 km 2 .
More than 300 different bird specimens are described. The Lake is visited more than 100 different migratory birds and their total number is more than 40 000. When the surface of the Azov Sea freezes, their number increases significantly [5].
Large blooms of algae and aquatic plants develop from nutrient-rich water pollution, leaving little oxygen for fish and other aquatic species, resulting in eutrophication and aquatic life suffocation. The overabundance of nutrients (nitrogen and phosphorus) in seas, lakes, rivers, and streams can cause eutrophication, a set of negative consequences. [6].
Paliastomi Lake is used as a cultural leisure zone. It also serves as an important tourist and recreational facility.
In the North-eastern part of the Lake, the Pichora River flows into the Lake crossing a large area of Western Georgia's agrarian settlements and significantly pollutes the Lake with nutrients. Another significant source of Paliastomi Lake pollution is so called "Airport Chanel" that is one of the main 'collectors' of sewage water in the city of Poti. The source is located at the North-eastern part of the Lake close to the fish factory that also pollutes the Lake, but only in November and December in anchovy fishing season .
The process of fish meal production involves the hydraulic discharge of fishes with loss of soluble proteins to the Sea [7]. Recycling the water used to unload fish from ships to factories will reduce the environmental impact [8]. These recycled fishmeal waste waters have high content of chemical oxygen demand (COD) protein and salinity (sodium, chloride, sulphate) [7,9]. In recent years, fisheries have often been depleted, which, according to the Environmental Protection Agency of Georgia, is caused by the lack of oxygen in water that is the result of the process of eutrophication in Paliastomi Lake [10].
Carnivorous activity or environmental contamination can cause infection in wild birds. Carnivorous and omnivorous wild birds are the most usually affected, as they eat food that may be contaminated, such as intestine, eat food that has fallen to the ground, or feed or live in contaminated water [11].
Salmonella spp. are known to be reservoirs in wild birds [11]. Salmonella has been discovered occasionally in the gut flora of wild birds in previous studies [12].

Chemical microbiological analysis of the water of Paliastomi Lake
On May [14][15]2017, an expedition to conduct chemical analysis of the chemical, microbiological and seabed sediments of Paliastomi Lake was organized. We selected four analysis and sampling points near Paliastomi Lake, adjacent to Collinbari Island: 1. Rangers' Base-1. 100 meters offshore from the ranger base; 2 Rangers' Base-2, at 100 m, from the base; Rangers' Base-3, at 500 m from Ranger base; and ranger base-4 near the fish processing plant, 150 m from the factory exit channel ( Figure 5) [13]. Paliastomi Lake water and seabed sampling, preservation, storage and transportation was done using ISO standard methods. The chemical properties of water organoleptic, chemical and microbiological indicators as well as seabed sediments were determined by field portable apparatus and stationary laboratory using ISO and GOST standard methods [15,116].
The pH value of Paliastomi Lake water is slightly more than pronounced due to the nature of the salts dissolved in it and the hydrolysis. According to samples 1, 2 and 3, the oxygen content is high at 7.3-7.8 mg / L, and the amount of oxygen dissolved according to the 4th data is relatively low and equals to 3.6 mg / L. The oxygen regime has a profound effect on the life-ability of the reservoir, the minimum dissolved oxygen content that ensures normal fish development is 5 mg / l O 2 / L, and its reduction to 2 mg / L results in massive fish mortality [5,9]. The concentration of dissolved oxygen in samples 1, 2 and 3 corresponds to class II-purified class of surface water quality, and class 4 is classified as contaminated, class 4. Waterbed sediments are formed as a result of deterioration of catchment rocks and soil cover following the soil surface washing. The composition of waterbed sediments in the Lake basin is regularly altered by constructing rocks in accordance with lithology and grain size [17,18]. In addition, as a result of sedimentation of minerals and organic matter in the Lake water, the water flows into the Lake and produces sediment on its bed. According to the literature, heavy metal contamination of seabed sediments is mainly caused by anthropogenic sources, residues of agriculture and enterprises working in various industries [17,18].
Paliastomi Lake sediments were sampled and studied (by ISO methods) in May of 2017 . Based on the geochemical background, the results of the analysis, the total copper content in the bottom sediments of Paliastomi Lake is lower than the permissible rates [2,15,19,20], and exceeds the permissible values in Georgia [2,18]. Lead and zinc content in Lake sediments may be considered as a natural background [2,18]. The content of manganese and iron in the seabed is less than the MPC.

Results of the microbiological analysis of Paliastomi Lake water and waterbed sediments
Since Paliastomi Lake is used for fishing, as well as for cultural recreation and swimming, it is necessary to determine the microbiological contamination of water causing various infectious diseases in order to maintain the necessary degree of the Lake water purity and ecological control.
There are very limited bacterial research data for Paliastomi Lake found in literary sources. On May of 14-15 and August 9-10 of 2017, an expedition to collect microbiological samples of Paliastomi Lake was organized by International Center for Environmental Research (ICFER). On March 29 and April 18, 2018, the Lake water and bed samples were collected for microbiological analysis by ICFER. Besides, on January 30, 2019, the Lake water samples were taken for microbiological analysis by ICFER.
Lake water sampling, storage, transports and microbiological analysis was performed according to international ISO and GOST standards.

Tests of surface water and Lake bed sediments
The bicrobiological analysis determined the total coliforms and the number of coli-forming bacteria in the intestinal tract. In samples 1, 2 and 4, the total coliforms are sufficiently high and in 100 ml of water they are 3000, 1280, 5000 CFU, while in the third sample, their number is 920 CFU / 100 ml respectively. Ecoli-grade bacteria were found in water samples 2 and 4, with a mean value of 100-40 ml per 100 ml 20-40 CFU (See Table 2). Their numbers increase with the migration of migratory birds in October and May.The total water content of the open water reservoirs -mesophilic aerobes and facultative anaerobic microorganisms (MAFA) as per the permitted norm in 1 ml is no more than 1000 CFU, while in 1, 2 and 3 water samples the total amount of MAFA varies from 800 to 5000 CFU / ml, and the maximum value (3500 CFU / ml) is reached in the 4th sample (See Table 1). Indicator of water quality (coli-titer; coli-index ) by ND coli-titer < 0,4; not less -111, coli-index; not more-9 Actual indicator of the quality of open water reservoir: coli-titer and coli-index: 100 ml,10 ml,1 ml,0,1 ml (Total volume of water 111 ml); coli-titer < 0,4 coli-index > 2380 Coli-titer not less -111, coli-index; not more -9 Outdoor reservoir water quality index MAFA actual rate by ND. Not more then coli-titer-0,4 Coli-index-2380 pH 6,8 The open water reservoir water quality index (coli titer, coli index) shall be as follows: coli -titer not less than 111 ml and coli-index not more than 9.
Coli index in water samples 1 and 4, at pH = 6.6 and pH = 6.8, was more than 2380 and coli index was less than 0.4. In the second and third samples, at pH = 6.5, the coli titre was reduced to 4 and the coli index was 230 (See Table 2). Therefore, high levels of bacterial contamination of the Lake water should be caused not only by the contamination of Paliastom Lake, but also by sewage discharges (directly into the Lake, without any treatment) from internally displaced persons' shelter and open landfills adjacent to it.
In January 29 2018 has been taken water sample from the lake Paliastomi in 50 meters right from Rangers's base (latitude 42.11842; longitude 41.70293) for the purification by bacteriophages. 9 The microbiological analyses shown that total amount of MAFAN in the water constituted 1500 CFU/ml when the permissible norms is not more than 1000 CFU/ml.
According to the Table 4, the general microbial parameters, the test water gives the characteristic picture of natural open water reservoirs (with small -moderate pollution). The rates of total microbial count (22 0 C) and fecal contamination (namely total coliforms) are relatively high, although coliform content was not detected.
The number of salmonella is relatively high. 2-2 isolates of fecal coliforms, enterococci, vibrios, and salmonella were sowed. The reason of low bacterial pollution might have been caused by 2 reasons: the fish factory was closed and it was not the period of waterfowl migration.  Chicken is given BC-1 a preparation with water and food as a prophylactic medicine. As a precaution, 10 milliliters of drinking water are mixed with 10 milliliters of BC-1 before being given. Birds are fed 2 milliliters in 10 milliliters of water for treatment purposes. For preventive measures, 1 milliliter of food-safe preparation is mixed with 1 milliliter water and sprayed on 20 grams of food. In terms of treatment, 1 milliliter of BC-1 is combined into 10 milliliters of food. The food is vigorously churned and fed to the birds to ensure an even distribution of preparation in the food. The chicken is given the preparation once a day in the morning. The preventive course lasts about 4-5 days. The treatment lasts 7-8 days. The averagepreventive daily dose for a 0-60-day-old chicken is 2X106, or 4X106 for 180-day-old chickens, and 8X106 for chickens older than 180 days. In the event of an epidemic, however, the use of antibiotics is not prohibited.
We suggest to adapt the proven methodology to wild birds, and do not exclude the possibility of conducting a study to apply the methodology in aquaculture in the marine of freshwater cages, however, in this case, we advocate that fish food should be processed with a specially compiled bacteriophage cocktail, which, if necessary, would not exclude the complex use of bacteriophages with antibiotics, which will significantly reduce the proportion of their use in aquaculture.

Water Pollution Modeling
The dissemination of pathogenic bacteria in the lake water was modeled. The following data is required to develop this model system:  Hydrodynamic characteristics of the water depths;  Water level;  Wind velocity;  Bacterial contamination points;  Bacterial monitoring;  Number of common coliforms.
For computational modeling of metals and coliform dissemination in Lake Paliastomi, a twodimensional numerical model based on the system of integration by vertical integration of water motion and continuity equations was used [20,21]. The program was compiled in Visual C ++. The model is based on the integration of the two-dimensional flow dynamics of the Lake and passive impedance in the water area using a modern high-resolution numerical scheme. In the integration process, the method of visualizing the results is applied. 13 The following parameter values were used in the model: Gravitational constant G=980 cm/sec 2 , Coriolis setting f = 0.9510-04 sec-1, Friction strain vector at the bottom τ →1 (τ , τ ) calculated by formulas: Atmospheric wind friction tension vector τ → 0 (τ , τ ) calculated by formulas: The occurrence of currents in Paliastomi Lake and distribution of pollutants during the northeast wind were discussed.
The real relief of Paliastom Lake was used in the modeling process, to determine: the vector fields of the lake currents, the free surface of the water, and the concentration of impurities in the lake water area. On a regular grid (size 26 x 29), experimental data were recorded. The data of the common coliforms obtained experimentally was transferred using linear interpolation by weights. The isolines on the drawing represent each value. The 4th source of pollution is located in the northeastern part of Lake Paliastomi. Consequently, the spatial distribution of isotopes in the lake area is heterogeneous. Concentration is minimal in 2-3 areas of the base, gradually increasing in a northerly direction and reaching its maximum in the area of the 4th base. The horizontal gradients of concentrations are large in the area surrounding the bases and gradually decrease as they move away from the bases in a northerly and northeasterly direction.   Figure 10 and Figure 11 show the change in concentrations of total coliforms over 24 hours. According to the drawings, there are 2 processes -diffuse and advectional transfer of common coliforms, resulting in a decrease in concentration in the maximum zone and transfer of common coliforms in the northeast direction, which coincides with the flow formed in Lake Paliastomi. The cyclonic current formed in the eastern part of the lake causes dissemination of common coliforms in the north-eastern part of the lake. Figure 12, Figure 13 and Figure 14 show the distribution of concentrations of common coliforms at the confluence of the Phichora River and the Paliastom Lake in the case of a west wind, determined by the second experiment. 15 The currents formed in Lake Paliastomi cause a change in the distribution of total coliforms, which is characterized by a decrease in concentration of 40 CFU / ml over 24 hours near the confluence of the Phichora River with Lake Paliastomi, as well as an increase of 32 CFU / ml in the vicinity of the fish farm.
We can conclude that the circulatory processes caused by turbulence in Lake Paliastomi lead to the redistribution of common coliforms throughout the water area. The distribution is uneven and especially intense in the middle of the north-western shore of the lake.
The given technology allows similar calculations to be performed for any reservoir with shallow depth. To do this, the user will only need to change the characteristics of the reservoir (horizontal dimensions, seabed relief and atmospheric wind).
The results thus obtained show that the general picture of microbiological contamination of Paliastom Lake is heterogeneous. It depends on the location of the sources of pollution, the intensity of pollution and the water currents of the lake formed by meteorological conditions. The model proposed in the paper describes qualitatively and quantitatively well the physical process taking place in a real environment and it can be used to predict changes in the dynamic characteristics of the relevant type of reservoirs. Through this model it is possible to further solve tasks such as the rational use of environmental resources and predict the ecological status [26].   Natural and artificial wetlands as main tools to treat wastewater flowing into the Lake The major instruments for treating wastewater flowing into the Lake are natural and artificial wetlands.
Due to its environmental benefits and relatively minimal operational and maintenance requirements, wetlands are increasingly being used to treat wastewaters. Different sources of information evidence an increasing use of wetlands to treat wastewaters owing to its environmental benefits and relatively low operational and maintenance requirements.
The use of wetlands for wastewater treatment is not novel, but the current expertise is gathering increased momentum in water industry due to the environmental benefits and lower operational and maintenance requirements of the given systems.
There are many different types of manufactured wetlands in use around the world, but the systems that are employed can be divided into two categories: Engineered Reedbed Systems and Integrated Constructed Wetlands.
The advantages of wastewater treatment in wetlands include environmental protection and enhancement, increased biodiversity, and carbon capture and storage.

Pollution from diffuse sources
In addition to the direct, unpurified waste water discharges, the pollution of the Lake ecosystem is also influenced by the diffuse entries from the agricultural lands in the catchment area. In addition to the proposed measures to treat the municipal wastewater, besides the land management measures are necessary what will lead to the reduction of nutrients and pesticides flowing into the catchment areas of the tributaries. To quantify this material input, on the one hand, modeling are suitable which, in accordance with the land use and the climatic and pedological conditions in the catchment area, balance the material flows. On the other hand, a realistic image of current load can be determined by means of monitoring the springs and headwater streams.

Modeling of diffuse material entries
The basic structure of modeling the diffuse inputs follows the simple load or export coefficient approach [26]. This is to be understood as an entry at the interface of the land path to the water path (still without retention in the water bed or the accompanying wetlands): Whereas F N,P is the average nutrient input into the water body of substance N or P in [kg/a], a N,Pi,t are the export coefficients of N or P of land use type i [kg/(ha*a)] within time t (for simple approaches: t = 1 year -here, the export coefficient includes already the part due to atmospheric deposition [28] and X i represents the area of land use type i [ha]. The first extension of this model approach is that the export coefficients are calculated, for example, depending on the substance concentration: When modeling the outputs from the areas, a fundamental distinction is made methodically (especially in conceptual models) between the land use types: the arable land, grassland, forest and settlement areas. The complexity of the summary calculations increases depending on the changes in the order of land use, forests and settled areas, grasslands and arable lands. due to the variability of land use.

Monitoring of springs and headwaters
The springs highlight the transition between groundwater and surface water. Springs dominated by near-surface groundwater (interflow), in particular, exhibit direct reactivity to material inputs in their catchment areas. Highly mobile nitrate nitrogen, as well as very mobile insecticides and their transformation products, make up this category. Due to its poor solubility, the phosphorus, which is likewise used in fertilization, is discharged via erosion in a particle-bound manner. In zones at risk of erosion, direct effects to prevent the phosphorus input can be achieved by simple measures in agriculture [29].
Numerous studies have shown that the nitrate nitrogen content in spring waters is mainly determined by three factors: hydrogeology, climate/seasonality and land use [30; 31; 321]. The primary determinant is land usage, particularly in semi-arid, agriculturally intensive areas (32). The actual entry into the water system can be determined via an integrated monitoring of spring waters typical of the land use pattern of the Paliastomi Lake catchment area. In order to capture the actual emissions from agriculture, the sub-basins of the springs to study must be free of the settlement influence. In addition, 1-2 springs without agriculture and settlement influence should be investigated in order to determine the background load.
At the selected spring sites, regular monitoring of nitrate contents and other basic physico-chemical water parameters over a minimum of two years is recommended. Recent studies have shown that this leads to similar results as complex continuous measuring devices [34].
In line with monitoring of springs and headwaters, new methods of monitoring of agricultural pollution of Paliastomi Lake by inflowing waters should be maintained.
From an operations standpoint, the low cost of operation of wastewater treatment in wetlands systems offers real savings in terms of energy use, demand on operations staff time and resources, as well as sludge production, handling, and disposal -all important considerations when managing the provision of effective wastewater treatment services within fiscal limits that are difficult to overcome.
In order to neutralize the contaminated sediments (e.g. heavy metals), it is necessary to remove them from the surface and bury them on the safe site, unless their high pollution endangers the water ecosystem.

Conclusions
Regular periodic inspections with minimal follow-up interventions are required for Integrated Constructed Wetland systems to maintain surface flows inside the ponds, maintain access to and from the ponds, and remove silt and organic debris that accumulates over time.
The preliminary results of microbiological and chemical analyses, combined with mathematical modeling of possible pathogenic bacteria dissemination in Paliastomi Lake, allow us to continuously monitor not only the inflowing waters of the lake, but also seasonal sources of bacterial pollution caused by migratory birds. According to the monitoring, localized spraying of Salmonella bacteriophage cocktail (SBC-1) will help limit bacterial contamination, and feeding the birds, who are potential carriers of pathogenic bacteria, food supplemented with SBC or locally selected phage cultures will promote pathogen elimination at the source, improve the habitat for local and migratory waterfowl and ensure the area's biosecurity. Furthermore, for the sake of bacterial security, all procedures will be done with the agricultural drones ( Figure 13, Figure  14).

Methodology
Our publication preparation team (PPT) provided study on the current state of the environment in the area adjacent to Paliastomi Lake, Kolkheti National Park determined the main sources of pollution, bird migration by seasons and fall of birds and fish. PPT has provided review on: the completed data on institutional and legal requirements and documents; the accomplished sanitary-biological studies in the given waters of the Lake; definition of dynamics of sanitary-microbial indicators in the flowing waters; An expedition was organized on May 14-15, 2017 to carry out chemical analysis of water and seabed sediments in Paliastomi Lake. We selected and fixed GPS coordinates of 4 sites.
Paliastomi Lake water and bottom sediments were sampled, preserved, stored and transported using ISO (ISO 8288-A-86; ISO 10523-2008) standard methods to determine te chemical characteristics of water, organoleptic and chemical parameters of water, as well as bottom sediments.
In order to complete the further research tasks, we organized an expedition to study the water in te Lake and waterbed sediments of Lake Paliastom in May 14-15, 2017 and August 9-10, 2017, as well as in March and April 2018 and January and March 2019. Lake water sampling, conservation, storage, transportation, as well as analysis of water organoleptic, chemical, microbiological and chemical parameters of bed sediments were determined according to international ISO standard methods andGOST: ISO 6222:1999; ISO 8199:2018; ISO 8189:1992; ISO 9308-1:2014; GOST 18963-73.
The dissemination of chemicals and pathogenic bacteria in the water of the Lake was modeled. The following data were compiled to develop this model system:  Hydrodynamic characteristics of water depths;  Water level;  Wind velocity;  Bacterial contamination points;  Bacterial monitoring;  Number of common coliforms.
For computational modeling of metals and coliform dissemination in Paliastomi Lake, a twodimensional numerical model based on the system of integration by vertical integration of water movement and continuity equations was used. The program is compiled in Visual C ++. The model is based on the integration of the two-dimensional flow dynamics of THE lake dynamics and passive impedance in the water area using a modern high-resolution numerical plan. During the integration, the method of visualizing the results was applied.