Nature Environment and Pollution Technology

B. Anupama ¹, Aboud S. Jumbe ¹, N. Nandini ¹

Affiliations
1 Department of Environmental Science, Bangalore University, Bangalore-560 056, Karnataka, IN

Abstract

Tanks in and around urban areas of Bangalore receive considerable amount of sewage, which has caused a severe and persistent microbial pollution. The main objective of this study was to measure level of faecal contamination in Madiwala lake using different techniques of E. coli estimation. Results show that the golden green colonies of coliforms with metallic sheen showed a luxuriant growth at 35°C with M-Endo Agar (M1106) at incubation time of 24-48 hrs. The growth of both E. coli and Enterobacter aerogens using M-Endo Agar plate was also luxuriant at 35°C temperature. But E. aerogens colonies were pink and mucoid while that of E. coli varied from pink to rose-red with metallic sheen. The confirmatory test using Agar M-392 confirmed the presence of Enterococcus fecalis in yellow colour colonies at luxuriant growth of 35°C temperature. The presumptive test results of different volumes of the lake samples after 24 and 48 hours using lauryl tryptose broth indicated significant colour change, gas production, and turbidity. Confirmed results showed gas production in brilliant green using lactose bile broth at 37°C in 48 hrs. The completed result with EMB agar inoculated with positively confirmed test tube incubated at for 24 hrs at 35°C showed greenish metallic sheen colonies while the coliform colonies inoculated on Nutrient Agar slant and a broth tube incubated for 48 hrs at 35°C showed growth as observed on slant with gas production in the broth tube. Moreover, Gram staining results showed Gram negative with sporing rods in the tested samples. The MPN Index of the lake sample was found to be 38/100mL. Water is generally considered safe for drinking if it contains fewer than 4 coliforms/100 mL. It is also considered safe if it contains less than 2 Enterococcus bacteria colonies/100mL of a sample. These observations indicate that environmental status of Madiwala lake with respect to microbial pollution is continuing to deteriorate.

Keywords

Madiwala Lake, Water Quality, Faecal Contamination, E. coli, Enterococcus fecalis, Enterobacter aerogens.

Full Text

   

C. Bindiya ¹, Ashok D. Hanjagi ², N. Nandini ¹, Aboud S. Jumbe ¹

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

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.

Full Text