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The soil contamination in the Ulaanbaatar city

THE SOIL CONTAMINATION IN THE ULAANBAATAR CITY
Myagmartseren PurevtserenMyagmarjav Indra2
1National University of Mongolia, Earth Sciences Faculty, 2State University of Agriculture, School of Agro- biology
Keywords: Heavy metals, soil contamination, residential area, land quality monitoring
Abstract
Хот суурин газрын мониторинг, чанарын хянан баталгааны гол судлагдахууны нэг нь хотожсон нутаг дэвсгэрийн хөрсний хүнд металлын хэмжээг түүний хүлцэх агууламж, байгалийн фон агууламжтай харьцуулан байнга тасралтгүй ажиглалт явуулах юм.
Энэ үйл ажиллагааны хүрээнд 2008 оны 6-8 сард Улаанбаатар хотын орон сууцны бүх хороолол, хотхонуудын хөрснөөс 0-10 см гүнд дээж авч, Нийслэлийн мэргэжлийн хяналтын төв лабораторид Co, Zn, Cu, Ni, Cr, Pb, Cdэлементүүдэд атом абсорбцийн спектрометрийн шинжилгээ хийлгэн, үр дүнг өмнө хийгдсэн эрдэмтэдийн судалгааны үр дүн болон хүлцэх агууламжтай харьцуулан хөрсний бохирдлын байдалд дүгнэлт гаргав.
Судалгаагаар орон сууцны хорооллуудын хөрсний хүнд металлын бохирдлын хэмжээ нийт агууламжийн дундажаар байгалийн болон хүлцэх агууламжтай харьцуулахад хэвийн хэмжээнд байна. Гэвч хар тугалга болон цайрын хэмжээ нь нийслэлийн баруун тал болон зүүн хойд талаар болон замуудын уулзвард ойр хэсэг, гэр хороололтой залгаа газруудад их хэмжээтэй гарлаа.
Introduction
The problem of environmental pollution due to toxic metals has begun to cause concern now in most major cities. The toxic heavy metals entering the ecosystem may lead to geoaccumulation, bioaccumulation and biomagnification. Heavy metals like Co, Cu, Zn, Ni and other trace elements are important for proper functioning of biological systems and their deficiency or excess could lead to a number of disorders / Ward, 1995/. Food chain contamination by heavy metals has become a burning issue in recent years because of their potential accumulation in biosystems through contaminated water, soil and air.
Therefore, a better understanding of heavy metal sources, their accumulation in the soil and the effect of their presence in urban residential areas seem to be particularly important issues of present-day research on urban land suitability assessments and land quality monitoring.
Materials and methods
The aim of this study is to assess the extent of heavy metal contamination of soil due to settlement with high concentration of population on residential land of Ulaanbaatar city. Samples of soils from different locations of city have been analyzed for seven heavy metals, viz. Co, Zn, Cu, Ni, Cr, Pb and Cd using atomic absorption spectrophotometry.

Figure 1. Sampling locations in 52 residential blocks.
Result
The results show the presence of some of the heavy metals in soils, beyond the limits of permissible limit standards. Concentration of Co, Zn, Cu, Ni, Cr, Pb and Cd (мg/kg dry wt) is represented in table 1.
Table 1. Heavy metal contamination in soils of residential areas
mg/kg dry wt
Sample
Pb
Cd
Cu
Zn
Ni
Co
Cr
Average total concentration of residential areas
25,92
0,98
11,58
61,61
13,24
BDL
0,07
Maximum concentration of residential areas
152,5
2,6
39,9
192,2
43,9
BDL
0,15
Minimum concentration of residential areas
1,5
0,05
BDL
1,7
0,55
BDL
BDL
Natural level *
/Hustay Natural Park/
24,7
-
22,0
51,3
34,8
-
66,9
Average total concentration of urban areas **
36,0
1,5
39,0
86,0
40,0
15,0
127,0
Permissible limit
35,0
5,0
60,0
100,0
50,0
30,0
100,0
BDL Below detection limit: Cu <0.001; Co <0.0025; Ni <0.0025
*O.Battulga, O.Batkhishig, 2002
** Mongolian academy of Sciences and National University of Mongolia, Earth Sciences Faculty, 1999.
The average total concentration of all metals in soil samples was lower than the permissible limits (limits are based on their effect on population health). However, maximum concentration of Zn and Pb falls within the range of standards (Figure 2,3,4).
Figure 2. Comparison of heavy metal concentration.
It was found that the average concentration of heavy metals in surface soils, i.e. Pb and Zn was more and less high than the natural concentration.
Figure 3. Zinc concentration in soils




Figure 4. Lead concentration in soils
Comparing the results of heavy metals in soil with their respective natural levels and mean level of city with has been studied earlier by scientists, it is observed that impact of settlement on residential area was found to be more than the unsettled open spaces of city and green belt.
The study reveals that built up residential area is not the main source of pollution of the soil environment and “ger” area with waste-contaminated soil containing variable amounts of heavy metals leads to increase in concentration of metals in the soil and other environmental components. Concentration of metals in soil will provide baseline data and there is a need for intensive sampling of the same for quantification of the results.
References
  1. Ward, N. I., Environmental analytical chemistry. In Trace Elements (eds Fifield, F. W. and Haines, P. J.), Blackie Academic and Professional, UK, 1995, pp. 320–328.
  2. Rajesh Kumar Sharma, Madhoolika Agrawal and Marshall, F. M., Effects of waste water irrigation on heavy metal accumulation in soil and plants. Paper presented at a National Seminar, Bangalore University, Bangalore, 2004, Abst. # 3., p. 8.
  3. O.Battulga, O.Batkhishig. Some micro element concentration in soil of Hustay natural park. Hustay #3. Ulaanbaatar, 2002.
  4. Eco geochemical research of the Ulaanbaatar city. Institue of geography, Mongolian academy of Sciences and National University of Mongolia, Earth Sciences Faculty, Ulaanbaatar, 1999.
  5. O.Battulga, O.Batkhishig. Ulaanbaatar city’s soil contamination study. State University of Agriculture, Research articles # 32. 2003.

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