9 102

Introduction Groundwater The present research project

• Objectives

• Experimental

• Results and Discussion

References

Introduction

• Water as a Natural Resource

Occurrence of Groundwater

The Present Research Project

• Highly populated.

• U.S.J.P.

• Nawinna garbage

dumping site.

• Agricultural

activities.

U.S.J.P.

Dumping Site

Paddy Fields

Objectives

• Determination of the quality of groundwater in the

land area around University of Sri Jayewardenepura

and Nawinna garbage dumping site.

• Investigate how the geology and human activities of

the area affect to the quality of groundwater.

• To make suggestion to avoid possible contamination

of groundwater.

Procedure Adopted in the Investigation

• Randomly selected 96 domestic wells.

• 14 water quality parameters.

• Interpretation of the results.

• Statistical analysis - ANOVA

Physical Parameters

1. Temperature

2. Conductivity

3. Turbidity

4. Total solids

5. Dissolved oxygen

Chemical Parameters1. pH

2. NO3- concentration

3. NO2- concentration

4. Total hardness5. Total iron concentration6. Zn concentration7. Pb concentration 8. Cr concentration9. Mn concentration10. Chemical oxygen demand

Biological Parameters

1. Biochemical oxygen demand

2. Coliform and E.coli test

MethodsParameter Method

Nitrite concentration Colorimetric method

Nitrate concentration UV spectrometric screening method

Total iron concentration Phenanthroline method

Total hardness EDTA titrimetric method

Dissolved oxygen Winkler method

Total solids Gravimetric method

Heavy metals Atomic absorption spectrometry

Chemical oxygen demand Open reflux method

Biochemical oxygen demand 5-day BOD test

Total Coiform and E.coli Multiple fermentation tube method

1. 0 Interpretation of the pH value

Comparatively low pH in cluster A.

Hydrolysis of heavy metal ions.

2.0 Interpretation of the Conductivity

Low conductivity values.

3.0 Interpretation of the Turbidity

Turbidity has a significant effect on microbial growth.

4.0 Interpretation of the Total Solids

TS and conductivity are high in cluster D.

5.0 Interpretation of the Total Hardness

The land is free from carbonate rocks.

5.1 Results Obtained from the Statistical Analysis

Analysis of Variance Source DF SS MS F PRegression 1 208489 208489 41.67 0.000

The regression equation isConductivity/µS cm-1 = 165 + 1.54 Hardness/ppm  

Hardness/ ppm

Conduct

ivit

y/µScm

-1

250200150100500

500

400

300

200

100

0

S 70.7314R-Sq 53.0%R-Sq(adj) 51.7%

Fitted Line PlotConductivity/µScm-1 = 164.8 + 1.544 Hardness/ppm

R2 = 51.7%Moderately positive correlation

6.0 Interpretation of the NO2-

concentration

About 22% of the samples.

Low DO level.

6.1 Results Obtained from the Statistical Analysis

One-way ANOVA: Nitrite versus Clusters

Source DF SS MS F PClusters_3 3 0.0008772 0.0002924 22.72 0.000

Clusters_3 -------+---------+---------+---------+--B (----*-----)C (-----*-----)D (-----*-----) -------+---------+---------+---------+-- -0.0050 0.0000 0.0050 0.0100

p< 0.05

There is a significant difference among the mean nitrite

concentrations of the clusters.

7.0 Interpretation of the NO3-

concentration

All the values are below the maximum permissible level.

7.1 Results Obtained from the Statistical Analysis

One-way ANOVA: Nitrate versus Clusters Source DF SS MS F PClusters 3 7.417 2.472 3.13 0.030Clusters = A subtracted from:Clusters Lower Center Upper ---------+---------+---------+---------+B -0.6635 -0.0117 0.6401 (--------*--------)C -1.0504 -0.3523 0.3458 (---------*---------)D -1.3165 -0.6584 -0.0003 (---------*--------) ---------+---------+---------+---------+ -0.70 0.00 0.70

p< 0.05

There is a significant difference among the mean nitrate

concentrations of the clusters.

8.0 Interpretation of Total Iron

Iron is present in laterite soil.Deposition of soft soil.

9.0 Interpretation of the Dissolved Oxygen

In fresh water DO level at 25°C is 8.4 mg dm-3 .Groundwater contamination by organic waste.

10. Interpretation of the Chemical Oxygen Demand

Organic and oxidizable inorganic substances.

11. Interpretation of the Manganese Concentration

50% of the samples are above the maximum desirable level.

Low pH.

12. Interpretation of the Zinc Concentration

High concentrations in cluster A.Low pH.

13. Interpretation of the BOD Values

About 40% of the samples. Presence of organic materials.

14. Interpretation of the Results of Coliform and E.coli Test

The maximum permissible level is10 coliform organisms per 100 cm3.

Out of 6 samples, 4 samples showed high MPN values.2 samples in clusters C and D were detected as

contaminated with E.coli bacteria.

Considering the pH value, water of 95.8% of

wells is not suitable for drinking.

With respect to conductivity and turbidity ,

well water is safe to drink.

Total solids were moderately low.

The NO2- concentrations were found to be

rather high.

Moderately high concentrations of NO3- were

found around the university.

The iron concentration and total hardness

were found to be low.

When considering the DO, COD, and BOD

values, the groundwater is polluted.

Zn and Mn concentrations were significant in

the area around the university.

Pb and Cr were found to be absent.

Groundwater contamination by Coliform and

E.coli bacteria was significant around the

garbage dumping site.

Some wells located in the direction of natural

water flow from the dumping site have been

affected adversely.

Human activities have been adversely affected

on the groundwater quality.

The deterioration of the quality of groundwater

takes time because undesirable products take

time to penetrate through the soil layers.

In general, groundwater in the area is not suitable

to be considered as potable water.

Suggestions for further workCarrying out investigations during both dry and

wet seasons.

Identification of the variation of the contamination

level with the distance from any significant

location by GPS measurements.

The wells that were highly polluted can be studied

separately.

Sanitary landfill sites should be designed.

3R concept.

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