Nature Environment and Pollution Technology

Open Access Open Access  Restricted Access Subscription Access

Environmental Degradation of Mallathalli Lake in Bangalore District, India - A Case Study


Affiliations
1 Department of Environmental Science, Bangalore University, Bangalore-560056, Karnataka, India
2 Department of Geography and Geoinformatics, Bangalore University, Bangalore-560056, Karnataka, India
 

An attempt was made to carry out baseline in-situ analysis of Malathalli lake. The lake falls within the Vrishabhavathi lake valley and Byramangala lake series. The catchment area of the lake is about 625ha. It is located on the western fringe of Bangalore city. Assessment of physico-chemical parameters was carried out mainly for pH, dissolved oxygen, BOD, suspended solids, total dissolved solids, alkalinity, hardness, nitrates, phosphates, sulphates, sodium, potassium, fluorides and chlorides. Malathalli is a contaminated lake with indicators of organic pollution showing highly variable sources of inputs. Dissolved oxygen is within lower limits at 3.25mg/L supporting the field observation on the dwindling fish catch in the lake. Moreover, the fish diversity is also disappearing leaving only those exotic species capable of tolerating lower DO levels. The average BOD is 6.0 mg/L. The pH is also above permissible limit at 8.9 showing alkaline nature of the lake. The total dissolved solids (TDS) were above permissible levels at 508 mg/L. For total hardness, the average was at 215.5 mg/L. Average calcium hardness was 86.6 mg/L as CaCO3. Inorganic ions such as sodium (Na+), potassium (K+), calcium (Ca2+) and magnesium (Mg2+) have varied concentrations during the months. The maximum sodium (Na+) concentration was in the month of June with 400 mg/L while the lowest was in January at 95.8 mg/L. Magnesium hardness was above permissible limit at 128.8 mg/L as CaCO3. This shows a trend in ionic imbalances through the months in the lake caused by artificial contamination. This can also be correlated with excessive presence of Mg+ ions at an average 31.4 mg/L. Chlorides were also above permissible level at 262 mg/L. Occurrence of hydroxide ions in natural water is very rare, but in January, hydroxide alkalinity of 3.3 mg/L as CaCO3 was found. Sulphates (SO4 2-) were with overall average range of 40.3 mg/L. For phosphates (PO4 3-), the average was at 4.4 mg/L. Nitrates also were within tolerable limits of ICMR and BIS. The average nitrates concentration was at 10.9 mg/L as nitrates. However, the chloride-bicarbonate ratio of 2.2 confirms the seriousness of the status of pollution in the lake.
User
Notifications
Font Size


Abstract Views: 171

PDF Views: 1




  • Environmental Degradation of Mallathalli Lake in Bangalore District, India - A Case Study

Abstract Views: 171  |  PDF Views: 1

Authors

C. Bindiya
Department of Environmental Science, Bangalore University, Bangalore-560056, Karnataka, India
Ashok D. Hanjagi
Department of Geography and Geoinformatics, Bangalore University, Bangalore-560056, Karnataka, India
N. Nandini
Department of Environmental Science, Bangalore University, Bangalore-560056, Karnataka, India
Aboud S. Jumbe
Department of Environmental Science, Bangalore University, Bangalore-560056, Karnataka, India

Abstract


An attempt was made to carry out baseline in-situ analysis of Malathalli lake. The lake falls within the Vrishabhavathi lake valley and Byramangala lake series. The catchment area of the lake is about 625ha. It is located on the western fringe of Bangalore city. Assessment of physico-chemical parameters was carried out mainly for pH, dissolved oxygen, BOD, suspended solids, total dissolved solids, alkalinity, hardness, nitrates, phosphates, sulphates, sodium, potassium, fluorides and chlorides. Malathalli is a contaminated lake with indicators of organic pollution showing highly variable sources of inputs. Dissolved oxygen is within lower limits at 3.25mg/L supporting the field observation on the dwindling fish catch in the lake. Moreover, the fish diversity is also disappearing leaving only those exotic species capable of tolerating lower DO levels. The average BOD is 6.0 mg/L. The pH is also above permissible limit at 8.9 showing alkaline nature of the lake. The total dissolved solids (TDS) were above permissible levels at 508 mg/L. For total hardness, the average was at 215.5 mg/L. Average calcium hardness was 86.6 mg/L as CaCO3. Inorganic ions such as sodium (Na+), potassium (K+), calcium (Ca2+) and magnesium (Mg2+) have varied concentrations during the months. The maximum sodium (Na+) concentration was in the month of June with 400 mg/L while the lowest was in January at 95.8 mg/L. Magnesium hardness was above permissible limit at 128.8 mg/L as CaCO3. This shows a trend in ionic imbalances through the months in the lake caused by artificial contamination. This can also be correlated with excessive presence of Mg+ ions at an average 31.4 mg/L. Chlorides were also above permissible level at 262 mg/L. Occurrence of hydroxide ions in natural water is very rare, but in January, hydroxide alkalinity of 3.3 mg/L as CaCO3 was found. Sulphates (SO4 2-) were with overall average range of 40.3 mg/L. For phosphates (PO4 3-), the average was at 4.4 mg/L. Nitrates also were within tolerable limits of ICMR and BIS. The average nitrates concentration was at 10.9 mg/L as nitrates. However, the chloride-bicarbonate ratio of 2.2 confirms the seriousness of the status of pollution in the lake.