This paper presents a survey of H2O chemical science of the Tuul River system in the environing country of Ulaanbaatar metropolis, Mongolia utilizing an extended dataset between 1998 and 2008, collected by the Central Laboratory of Environmental Monitoring. It presents the spatio-temporal appraisal and seasonal form of 15 hydro-chemical determinands at 15 supervising sites in the survey country. Human activity in the research country has a important impact on river H2O quality and alimentary concentrations. Levels of pollution in the downstream subdivision of the Tuul River are strongly dependent wastewater intervention degrees from the Central Wastewater Treatment Plant. Most of the high values of chemical determinand were estimated in winter clip due to low flows and in spring and fall, the high fluxes of foods are derived from snow thaw and storm H2O events. Lower values of hydro-chemicals determined in summer as a consequence of sufficient natural flow that can thin pollutant elements. Harmonizing to the Mongolian H2O quality categorization system, all subdivisions of the Tuul River and its feeders in the environing country of Ulaanbaatar metropolis belong to reasonably and to a great extent contaminated Waterss due to high concentration of ammonium. In conformity with European Union H2O quality criterion, the downstream subdivision of the Tuul River fails. In order to alter this state of affairs, operation sweetening of effluent intervention workss and unreal increase of dissolved O concentration become important to better the H2O quality significantly. Possibly a new effluent intervention works is needed for the Ulaanbaatar metropolis.

Introduction

Unpolluted Waterss in rivers are a critical natural resource, supplying imbibing and irrigation H2O for worlds, farm animal and agribusiness. However, H2O quality in many big river Waterss has deteriorated significantly world-wide due to anthropogenetic activities in the past two-three decennaries ( Ferrier, Edwards et al. 2001 ) . It is besides widely accepted that discharges from sewerage intervention workss provide major fluxes of P and N to rivers, preponderantly in populated urban countries ( Neal, Jarvie et Al. 2005 ; Jarvie, Neal et al. 2006 ) . Alimentary enrichment can ensue in inordinate growing of aquatic workss and decreases in dissolved O ( Neal, Jarvie et Al. 2002 ; Whitehead, Johnes et Al. 2002 ) .

Rising pollution degrees and the increasing demand for H2O and the increased discharges of pollutants are holding important impacts on the H2O rhythm and H2O quality ( Whitehead, Wilby et Al. 2006 ; Whitehead, Wilby et Al. 2009 ) . Climate alteration is besides get downing to hold some effects with increasing temperatures and changed rainfall forms. The increasing air temperatures and diminishing river flows in warmer months are the chief concerns, and intensive H2O usage is frequently constrained by the deficiency of natural low flow, and low flow rivers are more affected by outflowing discharges from metropoliss, industries, and agribusiness ( Mainstone and Parr 2002 ; Johnes 2007 ) . Surface Waterss in Mongolia have tended to diminish in recent old ages due to the combined consequence caused by the lessening of precipitation and the addition of possible vaporization as a consequence of lifting air temperature. This state of affairs indicates that drouths may happen more often due to the effects of planetary heating ( Sato, Kimura et Al. 2007 ) .

Over the last decennary, rapid urbanisation and increased industry have had a important impact on the H2O quality and chemical composing of rivers in the environing country of Ulaanbaatar metropolis ( Javzan, Sauleguli et Al. 2004 ) . Air and dirt pollution every bit good as accumulated wastes in the catchment country, are being transferred by surface overflow and inundation events into the local river systems and holding a important impact on the river H2O quality. Major causes of the H2O pollutants are mining industries in the lower basin of the Tuul River. More than 180 licensed excavation companies are runing in 145 km2 countries of the basin ( MNE 2006 ) . Water demand of the metropolis had increased by 20 % from 1998 to 2005. Population growing, urbanisation and strength of industries have created H2O development, impairment of natural H2O government and ecological debasement of the Tuul River basin ( Roza-Butler 2004 ) . The intervention efficiency of the CWTP every bit good as other Wastewater Treatment Plants ( WTP ) in the part is frequently unequal due to proficient and fiscal jobs. The efficiency of the CWTP was 71 % in 2002. This value dropped to 66 % in 2003. The works was non operated in May 2003 and April 2004 ( Orchlon 1995 ) .

For that ground, this survey has carried out a spatio-temporal H2O quality research of the Tuul River in the environing country of Ulaanbaatar metropolis, Mongolia in order to measure the recent province of H2O quality and beginnings of pollution. This paper presents the comprehensive analysis of H2O quality informations in the Tuul River and identifies spatio-temporal forms in H2O quality from 1998 to 2008.

The purposes of this research are i ) to measure spatio-temporal variableness of H2O quality determinands and foods of the Tuul River and its feeders ; two ) to measure the overall province of H2O quality and research its deductions and three ) to bring forth most recent H2O quality maps of the river utilizing the Mongolian H2O quality categorization and the EU criterions in the environing country of Ulaanbaatar metropolis.

Study country, informations and method

2.1. Study country

The survey was carried out in the environing country of Ulaanbaatar, the capital of Mongolia and population of the metropolis is about one million. The Tuul River, fluxing through the bosom of the Ulaanbaatar metropolis, is an environmentally, economically and socially important natural resource. The survey country covered the Tuul River and its three feeders, viz. the Terelj, Uliastai, Selbe Rivers and discharge from the CWTP. List of trying points and their geographical locations are shown in table 1 and figure 1. The point beginnings of pollution in the Tuul River are ill treated effluent intervention workss at Nalaikh ( 1400 m3 day-1 ) , Nisekh ( 400 m3 day-1 ) , CWTP ( 190000 m3 day-1 ) , Bio-industry ( 490 m3 day-1 ) and Bio-Songino ( 600 m3 day-1 ) . The biggest point beginning is CWTP, which is located in the western border of Ulaanbaatar metropolis ( Orchlon 1995 ) .

As shown in figure 1, there are five point beginnings of pollution ( some may overlapped in the figure ) marked by trigons and 15 points indicate the H2O quality monitoring sites. Pink lines represented the influxs into the chief river, a bluish line shown the Tuul River and polygon characteristics symbolized district of the metropolis and settling countries, severally.

Figure 1: Study country

Harmonizing to the Mongolian river categorization, developed by G.Davaa ( 2006 ) , which is based on long-run one-year mean flow, the Tuul River is a reasonably large river. Furthermore, the river pertains to 6th order of the Strahler river categorization system. In the district of Ulaanbaatar metropolis, there are about 50 watercourses and rivers ( most of them are dried up ) . Three of them, named the Selbe, the Uliastai and the Tuul, flow through the cardinal portion of the capital ( Altansukh 2008 ) .

Annual overflow of the Tuul River consists of three constituents viz. rainfall ( 69 % ) , groundwater flow ( 26 % ) and snow thaw ( 5 % ) based on an analysis by G.Davaa ( Basandorj and Davaa 2006 ) . The mean channel breadth of the river is 35 to 75 m during a low flow period, deepness is 0.8-3.5 m and the speed is 0.5-1.5 thousand s-1. The long-run one-year mean flow of the river is about 26.6 m3 s-1. The ascertained maximal discharge has reached 1580 m3 s-1 and 564 m3 s-1 at the Ulaanbaatar and the Terelj Stationss, severally. During the low flow period of the warm season, flows autumn to 1.86 M3s s-1 at the Ulaanbaatar station and 0.44 m3 s-1 at the Terelj station ( NAMHEM 1999 ) .

Figure 2: Maps of a ) The Tuul River catchment in Mongolian district and

B ) The catchment country, including the Tuul River and the survey country, UB metropolis

Features of the catchment country have been estimated by digital lift theoretical account based hydro-processing utilizing Shuttle Radar Topography Mission informations with 90 thousand declaration. The Tuul River catchment is one of 29 basins in Mongolia ( Figure 2a ) . It is situated in cardinal portion of the state and bounded by 108018’E-48030’N, 105022’E-46022’N, 102047’E-47050’N and 104047’E-48056’N, approximately. The catchment country is 57560.4 km2, which covers 3.67 % of the full district of Mongolia. The margin of the catchment country is 1998.5 kilometer, and the drainage denseness is 103.63 thousand km-2. The length of the Tuul River is 826.4 kilometer and the lifts of riverhead and the river mercantile establishment are 2272.0 m and 776.0 m, severally. Therefore, the river incline is 1.81 thousand km-1 and flows from the nor’-east to north. The headwaters of the river and most of the feeders originate in the cragged country that forms the northeast portion of the catchment ( Figure 2b ) . Dissimilar Numberss may happen from diverse beginnings due to the different method of catchment word picture.

The Tuul River basin has the Continental climatic characteristics that are characterized by broad fluctuation of one-year, monthly and day-to-day temperatures ; low scope of air humidness ; non-uniform distribution of precipitation ; cold and durable winter and warm summer. The showery period continues from June to August in the upper Tuul River basin, of which rainfall portions about 74 % of the one-year precipitation ( MNE 1997a ) . The one-year mean air temperature is -1.20C in the survey country. Annual minimal temperature reaches -39.60C in January, while maximal temperature reaches +34.50C during summer period ( Basandorj and Davaa 2006 ) .

The Tuul River quality is of course clean and rich in Ca hydrogen carbonate. Entire dissolved solid of the river H2O ranges from 100-210 milligram l-1, pH = 6.1-7.5 along its ranges. The river contains 28.1 milligram l-1 mineral, and it belongs to the hydro-carbonate category, Ca group. The chief cation is calcium, and dominant anion is a hydro-carbonate. Furthermore, cation proportion is Ca+2 & gt ; Mg+2 & gt ; ( Na+ + K+ ) and the anion ratio is HCO3- & gt ; SO4-2 & gt ; CI- . Naturally, anion and cation proportion every bit good as chemical content of the H2O lucifers with the pure H2O of river ( NAMHEM 1999 ) . However, chemical contents of the river all of a sudden alteration from the western portion of the metropolis. The chief factor of the chemical alterations is the incompletely treated effluent from the CWTP that is pouring into the Tuul River ( Altansukh 2005 ) . Harmonizing to the consequences of a hydrological study conducted in 2003, the hydrological government and its overflow formation zones of the Tuul River are bit by bit being changed and polluted by the colonies, intensive overgrazing, timbering, wild fires and improper effluent intervention in the river Bankss ( Basandorj and Davaa 2006 ) .

2.2. Chemical dataset

Surface H2O quality in the environing country of the Ulaanbaatar is being monitored at 14 points by 30 determinands in every month since 1980s. For this intent, 10 trying points along the Tuul River and 4 points at the feeders of the Tuul River ( 1 at the Terelj river, 1 at the Uliastai river, 2 at the Selbe river ) , were chosen by the Central Laboratory of Environmental Monitoring ( CLEM ) . Stationary hydro-biological monitoring of spineless species along the river has started since 1997 ( MNE 2006 ) .

Therefore in this survey, we focused on more recent datasets from 1998-2008, wholly 11 old ages, at those 14 sites. Additionally, we included chemical monitoring dataset of the CWTP discharge for rating of the intervention works consequence ( Figure 1 and Table 1 ) . In entire, 1980 samples were taken at 15 trying points along the Tuul River and its influxs ( feeders + the CWTP discharge ) and analysed by the CLEM and the research lab of CWTP. Water quality determinands presented in this paper are dissolved O ( DO ) , biological O demand ( BOD5 ) , ammonium ( NH4+-N ) , nitrite ( NO2 — N ) , nitrate ( NO3 — N ) , phosphate ( PO4-3 ) every bit good as major dissolved ions, such as Ca ( Ca+2 ) , Mg ( Mg+2 ) , Na ( Na+ ) sulfate ( SO4-2 ) , chloride ( Cl- ) , hydrogen carbonate ( HCO3- ) and others, wholly 15 variables.

Table 1: Spatial and temporal information of H2O quality trying

2.3. Analysis and quality categorization

In Mongolia, surface H2O quality is being chiefly estimated by three different methods.

Permissible degree of surface H2O variables specified in Mongolian National Standard 4586-98 ( 1998 )

Water quality categorization developed by Water sector of Ministry of Nature and Environment ( MNE ) in 1997.

Water quality index developed by Erdenebayar and Bulgan ( 2006 ) .

In this research, the 2nd method was used to sort the H2O quality. For surface H2O quality categorization, average values of H2O variables were calculated from 2004-2008 datasets ( Table 6 ) . For general position of spacial informations analysis, all chemical variables were deliberate norm of the full survey period ( Table 3 ) . Using the time-series of chemicals, tendency analysis was applied to find either the concentrations have increased or decreased during the clip period for temporal appraisal ( Table 5 ) . Furthermore, mean quarterly information from 1998-2008 were calculated in order to uncover seasonal variableness ( Figure 8 ) . Inter-determinand relationships of mean hydro-chemicals were assessed utilizing the Pearson correlativity technique and the consequences of relationship were shown in table 4. The relationships between mean general chemical concentrations were shown in correlativity matrix secret plans ( Figure 3 ) .

The one-year agencies of H2O quality datasets for the Tuul River and its influxs have been compared to both the Mongolian H2O quality categorization system ( WQCS ) and the EU H2O criterions, so that the river H2O quality classs can be assessed ( Figure 9 ) . Monitoring dataset of the CWTP was excluded from the statistical sum-up, the Pearson correlativity, tendency analysis, stoichiometric ratio, temporal analysis and quality categorization due to unsuitableness. Cause of, the CWTP discharge is to the full controlled by its operation. This paper presents spatio-temporal alterations of the natural Waterss, non technological Waterss. Use of the CWTP dataset is merely for comparing and ocular look of how it has the impact on the Tuul River.

Wholly, 53 variables included in the Mongolian WQCS ( MNE 1997b ) . However, 15 variables, which are concerned in this survey, are shown in table 2. Harmonizing to the Mongolian statute law, the categorization of surface Waterss with regard to their quality is given below every bit five categories, viz. : category 1: really clean, category 2: clean, category 3: somewhat polluted ; category 4: reasonably polluted ; category 5: to a great extent contaminated H2O. In table 2, threshold values of the Mongolian categorization and the EU criterion are shown.

Table 2: The Mongolian H2O quality categorization and the EU H2O criterion

With the purpose of categorization, the mean H2O quality for each applicable parametric quantity has been determined at all trying sites utilizing the information from 2004-2008 to uncover the most recent H2O quality position. Then information has been compared to the five categories and the EU criterion. The highest category has been chosen to each site and two classs of “ base on balls ” and “ fail ” were given when measuring H2O quality utilizing the EU criterion.

Consequences

3.1. Summary of mean hydro-chemical variables

Statistical sum-up of hydro-chemical concentrations from 1998-2008 is shown in table 3. A lower limit of three old ages informations are required to cipher mean values for each site. Average values used to cipher the proportion of major anion and cation charges by per centum ( Table 3 ) .

Table 3: Summary of variables from 1998-2008 for each monitoring site

It can be seen from table 1 and figure 1, foremost 10 trying points belong to the Tuul River, and last five monitoring sites are on the influxs. As mentioned antecedently, the monitoring site 15 is non included computation. Values scope of pH from 7.29-8.12 with the mean value of 7.59A±0.26, which is in the normal scope of river Waterss and was somewhat increment along the Tuul River. For suspended solid ( SS ) , value scope is more wide from 7.3 to 44.5 milligrams l-1 with the mean of 21.6A±12.2 mg l-1 ( n=14 ) . Calcium is the dominant cation ; hydro-carbonate is the chief anion.

The sum of Ca+2, Mg+2 and HCO3- in the rivers every bit good as their 1:2 stoichiometric ratio additive relationship suggests that there is overloaded of CO2 compared to sum of Ca and Mg due to likely associated with anthropogenetic beginning such as coal combustion houses for warming and cookery ( Figure 3a ) . The writer says that there is a long list of air pollution beginnings besides the traditional beginnings in the capital of Mongolia ( Guttikunda 2007 ) . Bi-variate secret plan of constituents of Na+ plus K+ versus Cl- simply fall on 1:1 stoichiometric ratio line, and it suggests that Waterss in the river are largely controlled by natural weathering ( Figure 3b ) .

Figure 3: Bi-variate secret plans a ) Ca+2, Mg+2 versus HCO3- ; B ) Na+ , K+ versus Cl-

Oxygen parametric quantities ( DO, BOD5 ) and foods concentrations ( NH4+ , NO2- , NO3- and PO4-3 ) are besides variable across the survey country which depends on the point and non-point pollution beginnings. DO scopes from 6.87-9.40 with the mean of 8.68A±0.81 mg l-1 and BOD values range from 1.8-15.8 milligrams l-1 with the mean of 4.6A±4.4 mg l-1. The average concentrations of foods across the country are different. For case, the concentration of ammonium varies from 0.11-6.5 milligrams l-1 with the norm of 1.38A±2.12 mg l-1 and concentrations are stable until trying point 6 and all of a sudden increase at point figure 7 with 6.47 milligrams l-1, so bit by bit diminish along the Tuul River. General form of P is same as ammonium. NO2- concentrations range between 0.003 and 0.22 milligrams l-1 with the norm of 0.056A±0.078 mg l-1 ; nitrate and nitrite are stable until point 6. After sudden increase, nitrification procedure intensively takes topographic point along the Tuul River.

3.2. Spatial form of hydro-chemicals

3.2.1. General chemical variables

Threshold values on the maps are based on five equal dividers of difference between upper limit and minimal values. As seen from table 3 and figure 4, several mean values on monitoring sites have been missed due to miss of some hydro-chemical analysis. Sixth threshold value gathered from the CWTP value.

The forms of mean values of general chemicals from 1998 to 2008 along the river are presented in figure 4. Major anions and cations show the similar spacial form in the survey country with lower concentration at the upper subdivision of the river and increased when fluxing downstream ( Figure 4a-f ) . The highest pH values were spotted in the colony country due to strong anthropogenetic influence. SS is variable with the lower concentration at the upper subdivision and highest concentration at the 7th sampling point ( Figure 4b ) . Along the Tuul River, spacial forms of Ca+2 plus Mg+2 and Na+ plus K+ are stable at first six monitoring sites and quickly increase at point figure 7 caused by the CWTP discharge and bit by bit diminish until point 10 due to dilution ( Figure 4c-d ) . Sulphate, P and hydro-carbonate have same forms as mentioned before ( Figure 4e-f ) .

3.2.2. Oxygen parametric quantities

Spatial distribution of mean BOD5 and DO values from 1998-2008 within the survey country are presented in figure 5. In the instance of BOD5, concentrations are by and large low in the upper ranges of the river. However, in downstream of Ulaanbaatar metropolis, where the CWTP discharge dominates the H2O with really hapless quality, this wastewater increases BOD5 to moderately high degrees. Along the lower ranges of the river, the high value bit by bit decreases ( Figure 5b ) . Sing to old forms, the DO is shown an opposite form in the survey country, reflecting the natural re-aeration of the H2O, where chemical and biological reactions such as the oxidization and nitrification procedure have consequence ( Figure 5a ) . There is one site in the Tuul River with low DO concentration, which is usually associated with discharge from the intervention works in the full twelvemonth operation. The waste H2O from that works contains a high sum of foods and other chemical substances and can do of major decreases of DO. This would decidedly kill aquatic zoologies and ecology in the stretch of the river system affected.

3.2.3. Foods

Spatial distribution forms of mean alimentary concentrations, NH4+ , NO2- , NO3- and PO43, are shown in figure 6. Even though these four determinands are variable across the survey country, the upper ranges of the river and feeders have comparatively low food degrees, which reflect the minimum impacts of human activity. The western subdivision of the Tuul River, on the other manus, has higher concentrations of foods due to dispatch from the intervention works, where both N and P are higher. The last point of the Tuul River by and large has low alimentary concentrations perchance due to the self-purification and biogeochemical procedures in the river ( Figure 6a-c ) .

Overall NO3- concentrations are low along the Tuul River except for the influxs, where the anthropogenetic activities strongly occur ( Figure 6c ) . The NO2- concentrations are comparatively unvarying until 6th trying point and downward tendency beyond the 7th site where reflect the nitrification processes taking topographic point down the river system ( Figure 6b ) . In footings of NH4+ and PO43- , relatively same forms can be seen from figure 6a, d. Those increased of alimentary concentrations at trying point 7 are mostly controlled by the point pollution beginning.

3.3. Inter-relationship of hydro-chemicals

With the intent of measuring the relationships among determinands, the Pearson correlativities for mean H2O hydro-chemical braces calculated ( Table 4 ) . For pH, there is a statistically important positive correlativity merely with Ca, Mg, hydro-carbonate and nitrate. SS has statistically important correlativities with all determinands except pH and NO3- . There are besides important positive correlativities among major dissolved cations and anions. DO has a clear negative relationship at the 0.05 important degree. Foods have largely positive correlativity with other hydro-chemicals except DO. Harmonizing to the Pearson ‘s correlativity at the certain degree, perfect positive relationship is 0.99 between ammonium and biological O demand at 99 per centum degree, and the weakest correlativity is 0.56 between ammonium and Ca at 95 per centum degree. Besides of that, correlativities between DO and NH4+ , PO4-3 are absolutely rearward -0.95.

Table 4: The Pearson correlativity for mean bi-hydro chemicals

3.4. Temporal tendencies in H2O quality

Annual mean values of hydro-chemicals between 1998 and 2008 used to temporal tendency analysis. Due to the broad scope of informations ( NH4+ 0.05-12.11, BOD5 1.28-30.07 and PO4-3 0.005-0.818 ) existent values transformed to log10 values. In instance of DO, primary informations applied to analysis. For slope computation of the tendency, all existent datasets were used.

Figure 7: Temporal fluctuations of quality variables at selected sites from 1998-2008

The time-series of NH4+ , BOD5, PO4-3 and DO at the monitoring sites 1, 6, 7, 10 are shown in figure 7. Base burden ( ID 1 ) , the upper range of the CWTP ( ID 6 ) , the lower range of the CWTP ( ID 7 ) and last point of the research subdivision of the river ( ID 10 ) , those points selected for farther analysis. The figure 7 shows clear and non clear tendency lines at the selected sites. Therefore, slope computation of all hydro-chemical variables to find upward or downward tendencies utilizing existent dataset and consequences of analysis at 14 trying points are shown in table 5. Positive values in the tabular array indicate there are upward, negative values show the downward tendency with different magnitude and 0.0 agencies, tendency is non obvious.

Table 5: Trend analysis of H2O determinands

There is a little downward tendency in DO at trying point with ID 1, a non clear tendency at 6, a considerable downward tendency with incline -0.4 and a descending tendency at last monitoring site along the Tuul River reflecting the anthropogenetic influence. Obviously, BOD has upward tendencies reciprocally related to DO variableness. In footings of ammonium concentration, there are upward tendencies at selected sites along the Tuul River ( Figure 7c ) , which may reflect the population growing, industrialisation and urbanisation since 1990s. Phosphorus at most sites, except the lower range of the CWTP shows non obvious tendencies ( Table 5 ) . Upward trends in most of the chemicals at site 7 could be due to improper intervention of the cardinal works. Decidedly, there are upward tendencies in NO2- and NO3- related to NH4+ tendency due to nitrification procedure, but non clearly seen from table 5.

3.5. Seasonal variableness of H2O quality

Average values of each season were calculated and used to seasonal appraisal. Average values of summer season screen from June until the terminal of the August, fall wrap between September and terminal of the November, winter screen December-February and spring include beginning of the March until May ( Figure 8 ) . Due to the broad scope of informations, existent values transformed to log10 values.

It can be seen from figure 8, higher concentrations of DO be given to happen in fall and lower values likely to happen in winter. There is a steady increase in DO from winter to autumn. This is most likely due to the fact that river H2O freezings, no interaction between H2O and other natural constituents and therefore natural re-aeration intermits. On the other manus, due to the temperature rises, so river flows and natural re-aeration takes topographic point. Besides of that, low DO and high BOD5 concentrations occur in winter, reversely, high DO and moo BOD5 values step in summer associated with the combination of changeless discharge from the CWTP and variable flow of the river in the full twelvemonth. The improper cleaned effluent from the intervention works is known to hold high BOD5, NH4+ , NO2- , NO3- and PO4-3 concentrations and these can do of major DO decrease.

The figure 8 shows that general forms of ammonium and P are same as BOD5 due to above mentioned grounds. However, the surface overflow is another non-point beginning of NH4+ and PO4-3 in clip of snow thaw in spring and rainfall session in fall. The high concentration of NH4+ and PO4-3 tend to happen in winter instead than during the remainder of the twelvemonth due to miss of river discharge.

Figure 8: Seasonal alterations of quality variables at selected sites from 1998-2008

In instance of ammonium concentration, seasonal variableness depends on both natural and human procedures. The higher value in winter clip is related to the river low flow and tremendous sum of discharge from the CWTP. Almost same concentration as winter in spring is derived from snow thaw and surface overflow, plus the intervention works. The lower value in summer is associated with non merely normal flow of the river, but besides related to re-aeration and nitrification procedure. The increased concentration in fall is derived from the rainfall-runoff procedure that washes off nitrogen from the catchment country.

In the full twelvemonth, all high values are measured at the trying point 7, which associated with the CWTP discharge. This sort of general form can be seen about all rivers, which run through large metropolis and affect by WTP. Further grounds for the function of pollution point beginning is seen from figure 4-6.

3.6. Water quality categorization system

The hydro-chemical variables have been used to measure the categorization of river H2O quality as defined by the Mongolian Water Quality Classification and the EU H2O criterion shown in table 6. For the most recent appraisal, norm of last five old ages ( 2004-2008 ) were calculated and compared to the threshold values ( Table 2 ) . The parametric quantities, which are non mentioned in the Mongolian categorization, excluded from the quality finding and comparing.

Table 6: Average value of hydro-chemicals from 2004-2008 for each monitoring site

Figure 9a shows the river H2O quality categories compared to the Mongolian categorization system. All of sites fall in category 4 or 5 and remainder of categories non visualized in the map due to high concentrations of NH4+ . The values of pH and NO3- scope classes 1 and 2. In instance of SS and DO concentrations, categories 1-4 estimated. Calcium, Mg, sulfate and chloride concentrations belong to category 1. Depend on specific value, remainder of variables falls into categories 1 to 5. The estimated worst variable is ammonium, which belongs to category 4 and 5 even in the upstream subdivision. Reason of this might be accumulated atmospheric deposition, which transported by the air current, and rainfall-runoff procedure in the upstream subdivision of the river. Obviously, high concentration of ammonium strongly related to the anthropogenetic influence in the downstream subdivision of the river and the metropolis Centre. This analysis expresses that the river system in the survey country is in comparatively hapless quality.

In footings of the EU criterion, the Tuul River is besides in hapless quality in the downstream subdivision as shown in figure 9b. On the map, the upstream subdivision of the Tuul River and its feeders are visualized green points, agencies passed the EU criterion. However, most of the base on balls values are about near to the threshold value.

Figure 9: The H2O quality position harmonizing to a ) Mongolian categorization and B ) EU criterion

3.7. Deductions of survey

Obviously, there is a demand to better the H2O quality in the Tuul River system in the environing country of the Ulaanbaatar metropolis in order to convey it up to the criterions required to run into category I or II of the Mongolian Water Quality Classification. The H2O quality and categorization analysis have shown the river system is neglecting the Mongolian criterions with 6 variables out of 12 in the lowest categories 4 and 5. General chemical variable analysis shown, that those sites fall in category 1 or 2. Spatially, the H2O quality decreases along the river. Several points and non-point pollution beginnings exist in the survey country. Therefore, H2O quality betterment of the river system becomes of import. A H2O quality patterning survey is followed to measure the effectivity of different scenarios, which could be used to better H2O quality in the hereafter.

In many states, pollution consequences from both point beginnings such as industrial effluent intervention plants and non-point beginnings such as from agricultural overflow when inordinate measures of fertilisers are applied to harvests. Impacts from urban and rural point beginnings remain a serious job with respect to come up H2O alimentary concentrations ( Jin, Whitehead et Al. 2010 ) . Naturally, as a consequence of flow through the cragged country, upstream of the river has more capableness of self-purification due to more re-aeration and more turbulency than downstream. This is the natural factor of the possibility to hive away pollutant elements in the river Waterss for a longer clip and distance ( Altansukh 2000 ) .

At the minute, the consequence of agricultural overflow is a non serious pollution beginning of the river system in the survey country. As the pollution is more associated with urbanisation, industrialisation and population growing in colony country and more related to dumbly located tourer cantonments in the upstream subdivision of the Tuul River.

Decisions and treatment

This survey has provided a comprehensive H2O chemical science appraisal of the Tuul River system in the environing country of Ulaanbaatar metropolis, Mongolia utilizing an extended dataset between 1998 and 2008, collected by the CLEM. It presents the spatio-temporal appraisal and seasonal form of 15 hydro-chemical determinands at 15 supervising sites in the survey country. The consequences suggest that mineral disintegration largely controls the major dissolved chemicals such as Ca+2 and HCO3- . Atmospheric deposition has besides of import influence on concentration of HCO3- due to inordinate burden of CO2 from different anthropogenetic beginnings. Human activity in the part has a important impact on BOD5, DO and alimentary concentrations. Increases of hydro-chemicals are strongly associated with the CWTP operation. General anions, cations and pH values fall in the normal scope in the full survey country. Generally, nitrate concentrations are low and nitrite dressed ores are high along the rivers, means pollution is freshly generated and beginning is near located from that point. Phosphate concentrations are chiefly linked to the point beginning. The estimated values of ammonium are really high in all monitoring sites that may tie in with atmospheric deposition and surface overflow in the catchment country. It besides has a strong impact on H2O quality categorization. Levels of pollution in the downstream subdivision ( sites 7-10 ) of the Tuul River are strongly dependent wastewater intervention degrees from the Central Wastewater Treatment Plant. This is a strongest point pollution beginning in the downstream subdivision of the Tuul River in the survey country. Then it is of course purified along the river flow, but non wholly purified even 50 kms downstream of the metropolis.

Harmonizing to the Mongolian WQCS, all subdivisions of the Tuul River and its feeders in the environing country of Ulaanbaatar metropolis belong to reasonably and to a great extent contaminated Waterss due to high concentration of ammonium. In conformity with EU H2O quality criterion, the downstream subdivision of the Tuul River fails. In order to alter this state of affairs, betterment of the operation efficiency of the CWTP becomes important to better the H2O quality significantly. Consequently, a modeling of H2O quality with different scenarios such as certain bounds on chemical concentrations of the CWTP discharge and unreal increase of DO concentration hold of import functions in the determination devising system. Make concentrate can be unnaturally increased utilizing bull rock wall ( non weir ) which has large plenty holes that fish and sediment can easy go through through. The incursion theory by Higbie, 1935 and a surface reclamation theoretical account that formalized Danckwerts in 1951 are theoretical portion of the DO unreal increase method. This method can be more eco-friendly ( economically and ecologically ) and works more efficaciously for the long period. Besides, several advantages can advert this method such as I ) stuffs that can utilize to construct the wall are natural, two ) no excess operation cost after the wall built, three ) no negative impact on river system, aquatic zoology and deposit can easy go through through by holes between bull rocks, four ) works expeditiously for long adequate clip, V ) easy to halt operation, merely take out rocks and six ) unreal pool will non make in upstream of the wall. However, some disadvantages might hold on this method such as I ) non applicable to large river, two ) the wall may be prostration due to strong plenty flow and moving ridge, and three ) heavy machines, like a Crane will necessitate.

Although the river system still remains extremely vulnerable to pollution. With colony country expansibility and industrialisation in the hereafter, it is recommended that the Water Authority of Mongolia should gauge vulnerable zone and protection distance from both riverbank and curtail any activity, which has a negative impact on river ecological system. Furthermore, the Mongolian Government should see the efficient operation of the CWTP in order to cut down the negative impact on the surface H2O pollution. Possibly a new effluent intervention works is needed for the Ulaanbaatar metropolis.