Heavy metal pollution of water and sediments in the rivers of hanoi, vietnam, and its effections on the quality of agricultural soil and crops

HEAVY METAL POLLUTION OF WATER AND SEDIMENTS IN THE RIVERS OF HANOI, VIETNAM, AND ITS EFFECTS ON THE QUALITY OF AGRICULTURAL SOIL AND CROPS Nguyen Thi Lan Huong 2008... HEAVY METAL POL

HEAVY METAL POLLUTION OF WATER AND SEDIMENTS IN THE RIVERS OF HANOI, VIETNAM, AND ITS EFFECTS ON THE QUALITY OF AGRICULTURAL SOIL AND CROPS

Nguyen Thi Lan Huong

2008

HEAVY METAL POLLUTION OF WATER AND SEDIMENTS IN THE RIVERS OF HANOI, VIETNAM, AND ITS EFFECTS ON THE QUALITY OF AGRICULTURAL SOIL AND CROPS

By

Nguyen Thi Lan Huong

A dissertation submitted in partial fulfillment of

the requirements for the degree of

Acknowledgements

First of all, I am extremely grateful to my advisor Prof Masami Ohtsubo for

accepting me as his PhD student and his patience, guidance and support during my study

I am deeply thankful to thanks Associate Prof Loretta Li (University of British

Columbia, Canada) for her counsel and many valuable suggestions towards accomplishing this dissertation

I would also like to Associate Prof Shin-Ichiro Wada and Associate Prof Takahiro Higashi (Kyushu University, Japan) for their many helpful comments

towards the writing of this thesis

I also wish to express my gratitude to Dr Motohei Kanayama and Ms Akiko Nakano for their assistance with ordering supplies and helping me in the laboratory procedures

I am very grateful to Ministry of education, culture, sports, science and technology, Government of Japan for providing the scholarship for this study

At last but above all, I am greatly indebted to my parents, husband, son and friends for their love, encouragement, and endless support

TABLE OF CONTENTS

ABSTRACT X LIST OF FIGURES V LIST OF TABLES VII CHAPTER 1

INTRODUCTION 1

1.1 STATEMENT OF THE PROBLEM 1

1.2 SCOPE OF OBJECTIVES 8

1.3 RESEARCH CONTRIBUTIONS 9

1.4 ORGANIZATION OF THESIS 9

1.5 REFERENCES 10

CHAPTER 2 ASSESSMENT OF WATER QUALITY AND ITS SUITABILITY FOR THE TO LICH AND KIM NGUU RIVERS IN HANOI CITY 14

2.1 INTRODUCTION 15

2.2 METHODOLOGY 16

2.2.1 Materials 16

2.2.2 Methods 17

2.3 RESULTS AND DISCUSSION 17

2.3.1 Chemical properties of water 17

2.3.2 Heavy metal pollution assessment 19

2.3.3 Suitability for Irrigation Water 23

2.4 CONCLUSIONS AND RECOMMENDATION 24

2 5 REFERENCES 25

CHAPTER 3 HEAVY METAL CONTAMINATION OF RIVER SEDIMENTS IN HANOI, VIETNAM 27

3.1 INTRODUCTION 29

3.2 MATERIALS AND METHODS 31

3.2.1 Materials and Field Sampling 31

3.2.2 Methodology 31

3.2.2.1 Chemical and Physical Properties of Sediment 31

3.2.2.2 Semi-quantitative estimates of mineralogical composition 32

3.2.2.3 Total heavy metal concentration 34

3.2.2.4 Selective Sequential Extraction 35

3.2.2.5 Batch leaching test 36

3.3 RESULTS AND DISCUSSION 37

3.3.1 Sediment Quality 37

3.3.2 Mineral Identification 37

3.3.3 Clay Mineralogical Characterization 39

3.3.4 Impact of Industrial Activities on the Quality of Sediment 40

3.3.5 Correlation between Organic Matter and Heavy Metal Concentration in Sediment 42

3.3.5 Distribution of Heavy Metal in Sediment Fractions 44

3.3.6 Leachibility and Mobility of Heavy Metals in the Sediments 48

3.4 CONCLUSIONS AND RECOMMENDATION 55

3.5 REFERENCES 56

CHAPTER 4 IMPACT OF RIVER POLLUTION ON AGRICULTURAL SOILS AND VEGETABLES IN A SUBURBAN AREA OF HANOI, VIETNAM 60

4.1 INTRODUCTION 62

4.2 MATERIALS AND METHODS 64

4.2.1 Irrigation Water, Sampling Site and Soil Samples 64

4.2.2 Methods 66

4.2.2.1 Chemical and Physical Properties of Agricultural Soils 66

4.2.2.2 Heavy Metal Concentration 66

4.2.2.4 Absorption Isotherm 66

4.2.2.5 Batch Leaching Test 67

4.3 RESULTS AND DISCUSSION 68

4.3.1 Properties of Agricultural Soil 68

4.3.2 Heavy Metal Concentration of Soil 70

4.3.3 Mobility of Heavy Metal 71

4.3.4 Adsorption Isotherm 75

4.3.5 Leaching Heavy Metals from Contaminated Soils 82

4.3.6 Fractionated Heavy Metals and Potential Leachability 85

4.3.7 Heavy Metal Concentration in Vegetable 87

4.3.8 Soil Plant Transfer Coefficients 89

4.4 CONCLUSIONS 91

4.5 REFERENCES 93

CHAPTER 5 HEAVY METAL CONTAMINATION OF SOIL AND RICE IN WASTEWATER-IRRIGATED PADDY FIELD IN A SUBURBAN AREA OF HANOI VIETNAM 97

5 1 INTRODUCTION 99

5 2 MATERIALS AND METHODS 101

5.2.1 Materials and Sampling Site 101

5.2.2 Methodology 101

5.2.2.1 Chemical and Physical Properties of Soil 101

5.2.2.2 Determination of Total Metal Concentration 102

5.2.2.3 Selective Sequential Extraction (SSE) of Heavy Metals 102

5.2.2.4 Absorption Isotherm 102

5.2.2.5 Leaching Test 102

5.3 RESULTS AND DISCUSSION 103

5.3.1 Properties of the Paddy Soil 103

5.3.2 Heavy Metal Concentration in the Soil 105

5.3.3 Heavy Metal Association with Soil Fractions 108

5.3.4 Heavy Metal Adsorption Capacity of Paddy Soils 111

5.3.5 Potential Leachability of Heavy Metals 117

5.3.6 Fractionated Heavy Metals and Potential Leachability 120

5.4 CONCLUSIONS 127

5.5 REFERENCES 128

CHAPTER 6 CONCLUSIONS AND RECOMMENDATIONS 133

6.1 CONCLUSIONS 133

6.2 RECOMMENDATIONS FOR THE FUTURE WORK 136

APPENDIX 138

LIST OF FIGURES

Figure 1.1 Study area 7

Figure 2.1 Location of sampling sites and factories 16

Figure 2.2 Relationship between total and water-soluble concentration and metal retained in suspended solid 20

Figure 3.2 The XRD patterns of the <2µm clay fraction of SD10, representing sediment sample of the To Lich and Kim Nguu Rivers in Hanoi Spacing is in nm Treatments: a, Mg-saturation and glycerol-solvation; b, Mg-saturation and air-drying; c, K-saturation and air-air-drying; d, K-saturation and heating at 5000C 39

Figure 3.3 Correlation between organic matter content and total heavy metal concentration organic fraction concentration 43

Figure 3.4 Heavy metal extracted via SSE from sediment samples 46

Figure 3.5 Average percentage of the respective heavy metal concentrations for each fraction of the sediments at all sampling sites, the variation of metal concentration due to the sampling sites is also indicated 47

Figure 3.6 Changes in the concentration of leached heavy metals by repeated washings with de-ionized water and the solutions of nitric acid, acetic acid and EDTA 49

Figure 3.7 Correlation between leached metal concentration and total metal concentration for the sediment samples subjected to leaching with water, acid and EDTA 51

Figure 3.8 Average of the ratio of leached metal concentration to total metal concentration for the sediment samples subjected to leaching with water, acid and EDTA Variation in the ratio from average is also indicated for the respective metal types and leaching solutions 51

Figure 3 9 Relationship between metal concentration of fraction and leached metal concentration of using different leaching solutions of sediment samples 53

Figure 3.10 Correlation between organic matter content and the ratio of leached metal concentration to total metal concentration for the sediment samples subjected to leaching with different types of solution 54

Figure 4 2 Heavy metal extracted via SSE from soil samples 73

Figure 4.3 Average percentage of the respective heavy metal concentrations for each fraction of the soil samples, the variation of metal concentration due to the sampling sites is also indicated 74

Figure 4.4 (a) Characteristics of Cd, Cr and Cu adsorption of Agricultural soil 76

Figure 4.4 (b) Characteristics of Ni Pb and Zn adsorption of Agricultural soil 77

Figure 4.5 (a) Freundlich and Langmuir adsorption isotherm models 80

for Cd, Cr and Ni of agricultural soil 80

Figure 4.5 (b) Freundlich and Langmuir adsorption isotherm models 81

for Ni, Pb and Zn of agricultural soil 81

Figure 4.6 Changes in the concentration of leached heavy metals by repeated washings with

de-ionized water and the solutions of nitric acid, acetic acid and EDTA 83

Figure 4.7 Correlation between leached metal concentration and total metal concentration for the soil samples subjected to leaching with water, acid and EDTA 84

Figure 4.8 Average of the ratio of leached metal concentration to total metal concentration for the soil samples subjected to leaching with water, acid and EDTA 84

Figure 4.9 Comparison of leached metal concentration for different treatments with sequentially fractionated heavy metal concentration in soil samples 86

Figure 4.10 Correlation between total heavy metal concentrations in the soils and vegetables 90

Figure 5.1 Location of soil and rice grain sampling 102

Figure 5.2 XRD patterns for the < 2µm clay fractions of the soil sample (S8) Spacing is in nm; Treatments a: Mg-saturation and glycerol – solvation, b: Mg-saturation and air-drying, c: K-saturation and air-drying, d: K-saturation and heating at 500oC 106

Figure 5.3 The metal concentration of soil samples following by distances from the road 106

Figure 5.4 Heavy metal extracted via SSE from soil samples 109

Figure 5.5 Average percentage of the respective heavy metal concentrations for each fraction of the soil samples, the variation of metal concentration due to the sampling sites is also indicated 110

Figure 5.6 (a) Characteristics of Cd, Cr and Cu adsorption of paddy soil 113

Figure 5.6 (b) Characteristics of Ni, Pb and Zn adsorption of paddy soil 114

Figure 5.7(a) Freundlich and Langmuir adsorption isotherm models 115

for Cd, Cr and Cu of paddy soil 115

Figure 5.7(b) Freundlich and Langmuir adsorption isotherm models 116

for Ni, Pb and Zn of paddy soil 116

Figure 5.8 Changes in the concentration of leached heavy metals by repeated washings with de-ionized water and the solutions of nitric acid, acetic acid and EDTA 118

Figure 5.9 Correlation between leached metal concentration and total metal concentration for the soil samples subjected to leaching with water, acid and EDTA 119

Figure 5.10 The average of the ratio of leached metal concentration to total metal concentration for soil samples subjected to leaching with water, acid and EDTA 119

Figure 5.11 Comparison of leached metal concentration for different treatments with sequentially fractionated heavy metal concentration in soil samples 121

Figure 5.12 Comparing between heavy metals leaching capacity by different solutions of sediment and soils 124

Figure 5.13 Comparing between leaching capacity of heavy metals of different solutions of sediment and soils 125

Figure 5.14 Correlation between heavy metal concentration in soil and rice grain 126

LIST OF TABLES

Table 2.1 Chemical properties in the water of the To Lich and Kim Nguu Rivers 18

Table 2.2 Correlation coefficient between chemical properties of water 18

Table 2.3 Heavy metal concentration in water from the To Lich and Kim Nguu Rivers 20

Table 2.4 Heavy metal concentration in suspended solid (g/kg) 22

Table 2.5 Information on the industry in the areas of the water sampling sites and the total heavy metal concentrations of water 23

Table 3.1 Sediment sample location and relationship between the types of industry and metal concentration in the sediment 33

Table 3 2 Chemical and physical properties of sediment samples 38

Table 3.3 Mineral contents (%) in the <2 µm clay fraction of sediment samples 40

Table 4.1 Chemical and physical properties of soil samples taken at different from the canal 69

Table 4.2 Mineral contents (%) in the <2 mm clay fraction of soil samples 70

Table 4.3 Total heavy metal concentration of soil samples (mg/kg) 71

Table 4.4 Distribution coefficient Kd (ml/g) for agricultural soil 78

Table 4.5 Total heavy metal concentration in vegetable (mg/kg) 88

Table 4.6 The range of transfer coefficients of metals and their suggested coefficient range 88

Table 5.1 Chemical and physical properties of soil samples 104

Table 5.2 Relative mineral contents in the <2µm clay fractions 104

Table 5.3 Total heavy metal concentration in soil samples 107

Table 5.4 Distribution coefficient Kd (ml/g) for soil 112

Table 5 5 Total heavy metal concentration of rice grain (mg kg-1) and transfer coefficient 126

Appendix Table 1 Concentration of sequentially fractionated Cd of Sediments (mg kg-1) 138

Table 2 Concentration of sequentially fractionated Cr of Sediments (mg kg-1) 138

Table 3 Concentration of sequentially fractionated Cu of Sediments (mg kg-1) 138

Table 4 Concentration of sequentially fractionated Ni of Sediments (mg kg-1) 139

Table 5 Concentration of sequentially fractionated Pb of Sediments (mg kg-1) 139

Table 6 Concentration of sequentially fractionated Zn of Sediments (mg kg-1) 139

Table 7 Concentration of sequentially fractionated Cd of Agricultural soil (mg kg-1) 140

Table 8 Concentration of sequentially fractionated Cr of Agricultural soil (mg kg-1) 140

Table 9 Concentration of sequentially fractionated Cu of Agricultural soil (mg kg-1) 140

Table 10 Concentration of sequentially fractionated Ni of Agricultural soil (mg kg-1) 141

Table 11 Concentration of sequentially fractionated Pb of Agricultural soil (mg kg-1) 141

Table 12 Concentration of sequentially fractionated Zn of Agricultural soil (mg kg-1) 141

Table 13 Concentration of sequentially fractionated Cd of Paddy soil (mg kg-1) 142

Table 14 Concentration of sequentially fractionated Cr of Paddy soil (mg kg-1) 142

Table 15 Concentration of sequentially fractionated Cu of Paddy soil (mg kg-1) 142

Table 16 Concentration of sequentially fractionated Ni of Paddy soil (mg kg-1) 143

Table 17 Concentration of sequentially fractionated Pb of Paddy soil (mg kg-1) 143

Table 18 Concentration of sequentially fractionated Zn of Paddy soil (mg kg-1) 143

Table 19 Adoption Isotherm of Cd of Sediment 144

Table 20 Adoption Isotherm of Cr of Sediment 145

Table 21 Adoption Isotherm of Cu of Sediment 146

Table 22 Adoption Isotherm of Ni of Sediment 147

Table 23 Adoption Isotherm of Pb of Sediment 148

Table 24 Adoption Isotherm of Zn of Sediment 149

Table 25 Adoption Isotherm of Cd of Agricultural soil 150

Table 26 Adoption Isotherm of Cr of Agricultural soil 150

Table 27 Adoption Isotherm of Cu of Agricultural soil 151

Table 28 Adoption Isotherm of Ni of Agricultural soil 151

Table 29 Adoption Isotherm of Pb of Agricultural soil 152

Table 30 Adoption Isotherm of Zn of Agricultural soil 152

Table 31 Adoption Isotherm of Cd of Paddy soil 153

Table 32 Adoption Isotherm of Cr of Paddy soil 154

Table 33 Adoption Isotherm of Cu of Paddy soil 155

Table 34 Adoption Isotherm of Ni of Paddy soil 156

Table 35 Adoption Isotherm of Pb of Paddy soil 157

Table 36 Adoption Isotherm of Zn of Paddy soil 158

Table 37 Leached concentration of Cd by different solutions of 5 times washing of Sediment (mg kg-1) 159

Table 38 Leached concentration of Cr by different solutions of 5 times washing of Sediment (mg kg-1) 159

Table 39 Leached concentration of Cu by different solutions of 5 times washing of Sediment (mg kg-1) 160

Table 40 Leached concentration of Ni by different solutions of 5 times washing of Sediment (mg kg-1) 160

Table 41 Leached concentration of Pb by different solutions of 5 times washing of Sediment (mg kg-1) 161

Table 42 Leached concentration of Zn by different solutions of 5 times washing of Sediment (mg kg-1) 161

Table 43 Leached concentration of Cd by different solutions of 5 times washing of

Agricultural soil (mg kg-1) 162 Table 44 Leached concentration of Cr by different solutions of 5 times washing of

Agricultural soil (mg kg-1) 162 Table 45 Leached concentration of Cu by different solutions of 5 times washing of

Agricultural soil (mg kg-1) 163 Table 46 Leached concentration of Ni by different solutions of 5 times washing of

Agricultural soil (mg kg-1) 163 Table 47 Leached concentration of Pb by different solutions of 5 times washing of

Agricultural soil (mg kg-1) 164 Table 48 Leached concentration of Zn by different solutions of 5 times washing of

Agricultural soil (mg kg-1) 164 Table 49 Leached concentration of Cd by different solutions of 5 times washing of Paddy

soil (mg kg-1) 165 Table 50 Leached concentration of Cr by different solutions of 5 times washing of Paddy soil

(mg kg-1) 165 Table 51 Leached concentration of Cu by different solutions of 5 times washing of Paddy

soil (mg kg-1) 166 Table 52 Leached concentration of Ni by different solutions of 5 times washing of Paddy soil

(mg kg-1) 166 Table 53 Leached concentration of Pb by different solutions of 5 times washing of Paddy soil

(mg kg-1) 167 Table 54 Leached concentration of Zn by different solutions of 5 times washing of Paddy

soil (mg kg-1) 167

ABSTRACT

Heavy metal pollution is one of the most topical environmental problems Many communities have become increasingly aware of and concerned by heavy metal pollution in relation to their everyday lives Industrial, agricultural and domestic wastes are continuously discharged heavy metals into water-bodies Encouraging wastewater reuse in agricultural has important economic and environmental benefits, such as conserving water and utilizing nutrients However, using untreated wastewater also poses certain environmental and health risks, including environmental health risks to users and consumers of products utilizing wastewater

Hanoi has experienced rapid economical growth and urban expansion in the last decades Wastewater from households and industries are discharged into the To Lich and Kim Nguu Rivers which today function mainly as the sewage and drainage systems

of Hanoi In peri-urban areas of Hanoi, water from those rivers also serves as the source

of water and nutrients for food production in lakes, ponds and heavily irrigated fields However, inappropriate city planning and wastewater management for both industry and household has caused various environmental problems including the heavy metal pollution of surface water, sediments, soils and crops This research work has concentrated to evaluate heavy metal pollution of the water and sediment in the To Lich and Kim Nguu Rivers and its effects on the quality of agricultural soil and crops in Hanoi, Vietnam

The To Lich and Kim Nguu Rivers, laden with untreated waste from industrial sources, serves as a source of water for irrigating vegetable farm In order to assess the water quality of stream water in the To Lich and Kim Nguu Rivers and the suitability of water quality for irrigation, the chemical properties and heavy metal concentrations of the eight surface water samples were determined The results showed that water from

the rivers was heavily polluted with organic matter and heavy metals such as Pb, Cu,

Zn, Cr, Cd and Ni Dissolved oxygen, chemical oxygen demand, and total suspended solids, and the concentrations of all heavy metals exceeded the Vietnamese standard for surface water quality in all investigated sites The concentrations of some heavy metals such as Cu, Cd, Cr and Ni were over the internationally recommended WHO maximum limits for irrigation water A wide variation in heavy metal concentration of water due

to metal types is the result of wastewater discharged from different industrial sources

In order to assess the heavy metal contamination in the To Lich and Kim Nguu Rivers, twelve sediment samples from above river system were taken and analyzed the chemical, physical, heavy metal concentration, selective sequential extraction and leaching test The present study shows that sediments in the To Lich and Kim Nguu Rivers are heavily polluted with heavy metals (220 to 475 mg/kg for Cu, 260 to 665 mg/kg for Pb, 250 to 535 mg/kg for Zn, 2.5 to 40 mg/kg for Cd, 505 to 655 mg/kg for

Cr, and 48 to 165 mg/kg for Ni) Metal concentrations in sediments were indicated to

be closely related to the type of manufacturing plants located along the rivers The heavy metals were bound with sediment particles through phases such as exchangeable, carbonate, oxide, organic matter and residual The percentage of each phase was different among metal types; the organic matter and the oxide were predominant for the group of Cu, Pb and Ni and the group of Zn and Cd, respectively, and each phase was almost equal for Cr Total heavy metal concentration in the sediment was correlated with organic matter content for Cu, Pb and Ni while no correlation was found for Cd,

Zn and Cr The EDTA caused high heavy metal leachability compared to water, acetic acid and nitric acid Average potential leachability decreased in the order: Cd > Ni > Cr

> Cu = Zn > Pb The leachability exhibited a tendency of decreasing with increasing organic matter for heavy metals other than Cr and Zn

In order to identify the impact of waste-water irrigation on the level of heavy metals in the agricultural soils and vegetables, and to predict their potential mobility and bioavailability, eight soil samples were collected from the locations of different distance from the canal at agricultural field in Tam Hiep, Thanh Tri, Hanoi The concentrations of all heavy metals in the study site was much higher than the background level in that area, and exceeded the permissible level of the Vietnamese standard for Cd, Cu, Ni, Pb and Zn The concentrations of Zn, Ni and Pb in the surface soil exhibited marked decreases with distance from the road The results of selective sequential extraction procedure indicated that dominant fractions were oxide, organic and residual for Ni, Pb and Zn, organic and oxide for Cr, oxide for Cd, and organic for

Cu The different heavy metals had different adsorption isotherms The q (metal

sorption concentration) value was 121 times for Cd, 12 times for Cr, 22 times for Cu,

59 times for Ni, 26 times for Pb and 21 times for Zn concentration found on the site The absorption capacity of heavy metals in soil followed the order of Cu > Cr > Ni >

Pb > Zn > Cd Leaching tests for water and acid indicated that the ratio of leached metal concentration to total metal concentration in the soil decreased in the order: Cd >

Ni > Cr > Pb > Cu > Zn, and for the EDTA treatment was in the order: Cd > Ni > Cr >

Zn > Cu > Pb The EDTA treatment gave higher leaching than other treatments By leaching with water and acid, all heavy metals were released fully from exchangeable fraction, and some heavy metals were fully from carbonate and oxide fractions The concentrations of Cd, Cu, Ni, Pb and Zn in the vegetables exceeded the Vietnamese standard The transfer coefficient for the metals was in the order: Zn > Ni > Cu > Cd =

Cr > Pb

The present study also deals with the heavy metal contamination of paddy soil and rice grain subjected to the irrigation water polluted with wastes from various

industrial plants in Hanoi The retention and potential mobility of heavy metals were assessed based on the contents of total and fractionated heavy metals in the soil and their leachability Heavy metal contents in rice grain were also determined Eleven soil samples were collected from the locations of different distance from the edge of road in Hoang Liet, Thanh Tri, Hanoi The concentrations of all heavy metals in the study site was much higher than the background level in that area, and exceeded the permissible level of the Vietnamese standard for Cd, Cu, Pb and Zn The concentrations of Zn, Ni and Pb in the surface soil exhibited marked decreases with distance from the road The results of selective sequential extraction procedure indicated that dominant fractions were oxide, organic and residual for Cd, Ni, Pb and Zn, and organic and residual for Cr, and organic for Cu The different heavy metals had different adsorption isotherms The

q (metal sorption concentration) value was 121 times for Cd, 12 times for Cr, 22 times

for Cu, 59 times for Ni, 26 times for Pb and 21 times for Zn concentration found on the site The absorption capacity of heavy metals in soil followed the order of Cu > Cr > Ni

> Pb > Zn > Cd Leaching tests for water and acid indicated that the ratio of leached metal concentration to total metal concentration in the soil decreased in the order: Cd >

Ni > Cr > Pb > Cu > Zn, and for the EDTA treatment was in the order: Cd > Ni > Cr >

Zn > Cu > Pb The EDTA treatment gave higher leaching than other treatments By leaching with water and acid, all heavy metals were released fully from exchangeable fraction, and some heavy metals were fully from carbonate and oxide fractions The concentrations of Cu, Ni, Zn in the rice grain met the WHO standard while those of Cr and Pb exceeded the permissible level of the standard The transfer coefficient for the metals was in the order: Zn > Ni > Cu > Cd = Cr > Pb

To reduce the pollutants discharged from plants, countermeasures by the government and the technological improvement of wastewater treatment in

manufacturing processes are needed In these cases, EDTA should be used to remove or minimize heavy metals from contaminated sediments and soils

Key words: Heavy metal, Water quality, Sediment, Agricultural soil, Vegetable,

Rice grain, Selective Sequent Fraction, Leachability, Industrial effluent

CHAPTER 1 INTRODUCTION

1.1 STATEMENT OF THE PROBLEM

Heavy metal pollution is one of the most topical environmental problems Many communities have become increasingly aware of and concerned by heavy metal pollution in relation to their everyday lives Industrial, agricultural and domestic wastes are continuously discharged heavy metals into water-bodies Encouraging wastewater reuse in agricultural has important economic and environmental benefits, such as conserving water and utilizing nutrients However, using untreated wastewater also poses certain environmental and health risks, including environmental health

risks to users and consumers of products utilizing wastewater (Venditti et al., 2000)

Sediment is the result of deposition of solid material from the water Under certain hydrodynamic conditions, suspended solids settle along the bottom of watercourses or lake to form sediment Sediment may act as sources as well as sinks for certain heavy metals, and have the capacity to accumulate heavy metals and other

contaminants over time (Rickert et al., 1977) Forstner and Muller (1981) showed that

sediments in coastal regions near industrial and urban areas are typically polluted by heavy metals, which are usually present in amounts several times higher than their natural background levels The accumulation of heavy metals in the sediment is mainly a result of biogenuos and lithogenuos formations Contaminated sediments are soils, sand, organic matter, or minerals that accumulate on the bottom of a water body and contain toxic hazardous materials that may adversely affect human health by

being incorporated in to food chain (Klank et al., 2006)

The associations of heavy metals with suspended solid and bed sediment, and the dynamic nature of the stream environment, have generated interest in the past three decades in determining the accumulation and concentrations of the key heavy

metals in sediments (Yousef et al., 1994) Most of the heavy metals are absorbed on

suspended particulate matter that can be transported into the sediment by flocculation and sedimentation Sediments are an integral but ambiguous part of water systems At the sediment-water interface, particularly with the oxide zone, enhanced mineralization processes occur These microbial catalyzed reactions may change both the minerals on which heavy metals are bound and their speciation and therefore also

the mobility of the heavy metals (Mark et al., 1982) By providing the substrate for

organisms and interacting with the overlying water; sediments play an essential role to

the aquatic ecosystem and highly accumulate heavy metals concentrations (Rickert et al., 1977; Klank et al., 2006)

Heavy metal pollution in soils has attracted an increasing attention around the world in past decades Soil may be contaminated by heavy metals from both natural and anthropogenic sources Sources of anthropogenic metal contamination in soils include urban and industrial wastes; mining and smelting of non ferrous metals and metallurgical industries (Bermond, 2001) Regulatory authorities’ emphasized aspects

of water quality, government agencies have recently given greater attention to soil, recognizing its role as a repository of much pollution, as a transmitter of undesirable

materials to the groundwater and a supplier of contaminants to crops (Salemaa et al.,

2001) There is a growing concern that many soils in Japan and central Europe either have become or will soon be overloaded with toxic metals at the current anthropogenic input (Olive, 1997)

Although heavy metals naturally occur in the earth’s crust, they tend to accumulate in soil at toxic level because of irrigation application of sewage sludge that contains heavy metal as well as contamination caused by industry, fast growing populations and increasing urbanization, and often non-existent or ineffective

wastewater treatment facility (Bohn et al., 1985; Chen et al., 2007) Heavy metals are

highly persistent in soil with residence time in the order of thousands of years The main mechanisms by which heavy metals are retained in soil are adsorption including

ion exchange, precipitation, co-precipitation and organic biding (Nolan et al., 2005)

Once on the soil, heavy metals will undergo streaming over the soil and retention or leaching through floor horizons In this case, they may be more or less mobile and then either become more soluble or carried by water into the soil Excessive accumulation of heavy metals can have deleterious effects on soil fertility, affect ecosystem functions and constitute a health risk to animals and human beings (Mc Grath, 1987)

Plants are importance component of ecosystems as they transfer heavy metals from a biotic into biotic environments In polluted areas, the effect of industrial effluents on soils and the use of municipal and industrial wastewater for irrigation crops are well documented, and also the transfer of toxic heavy metals from soils to

plants is of great concern (Chojnacka et al., 2005; Nolan et al., 2005) One important

dietary uptake pathway could be through plants irrigated with contaminated wastewater The primary sources of heavy metals from the environment to plants are: air, water and the soil (Hamilton, 1995) Soils irrigated by wastewater accumulate heavy metals in the surface soil When the capacity of the soil to retain heavy metals

is reduced due to repeated use of wastewater, soil can release heavy metals into ground water and soil solution available for plant uptake (Alloway, 1995)

Many studies have shown that soil significantly affected the uptake of heavy metals by many varieties of plants in different sites and the concentrations of heavy metals in the plants were correlated with the total metal concentrations in the soils Furthermore, many physicochemical characteristics of soils such as pH, organic matter content, and cation exchange capacity, can impact the heavy metal accumulation and affect the availability of heavy metals for uptake by plants

(Mandaokar et al., 1994; Alloway, 1995) Moreover, the uptake and accumulation of

heavy metal by plants are dominantly dependent on the available rather total heavy

metal in the soil

The consumption of polluted plants is one of the major pathways for heavy metals entering the human bodies It is known that serious systemic health problems can develop as a result of excessive accumulation of dietary heavy metals in human body (Olive, 1997) Heavy metals are extremely persistent in the environment; they are nonbiodegradable and nonthermo-degradable and thus readily accumulated to toxic levels (Brigden and Santillo, 2004) Heavy metals are harmful to human health because

of their toxicity Cadmium (Cd) is highly toxic and accumulative, and kidney in human and animals is targeted by cadmium toxicity Other diseases include skeletal disorders

such as osteoporosis or osteomalacia (softening of the bones) as well as the

development of hypertension (high blood pressure) and heart disease (Brigden and Santillo, 2004) Lead (Pb) is one of the most toxic elements naturally occurring on Earth High concentration of lead can cause irreversible brain damage, seizure and coma, and death if not treated immediately The kidney is also targeted by Lead toxicity and impaired at moderate to high level of lead concentrations Other signs/symptoms of lead toxicity include gastrointestinal disturbances-abdominal pain cramps constipation anorexia, weight loss-immunosuppression (Brigden and Santillo, 2004)

Hanoi City, Vietnam, lies in the Red River Delta, borders the hilly provinces

of Vinh Phu and Bac Thai to the north, the provinces of Ha Bac and Hai Hung to the east, and the province of Ha Tay to the south and the province of Ha Tay and Vinh Phu to the west The city of Hanoi is situated from longitude 20o25' to 21o2'north and from latitude 105o15' to 106o03' east It is situated in a tropical area having a strong monsoon influence Hanoi is endowed with all the four seasons: spring, summer, autumn and winter Climate in Hanoi can be divided into two distinct seasons: the dry and the rainy seasons The dry season starts from October to April This is the period characterized by spells of cold wind and drizzles The rainy season starts in May and ends in September, there are many torrential rains and fierce sunshine in this period

Currently, Vietnam is going through a period of industrialization and modernization and according to the economic development strategy up to 2020, and Hanoi, as the capital city, is a central part of this development During this period of high economic growth, the process of transforming a rural economy into an industrialized one will impose pressure on the exploitation of natural resources and increase the amount of environmental hazards It is well known that in low-income countries with insufficient resources for investment in wastewater treatment and a lack of capacity to enforce legislation, the farmers should use the untreated wastewater for their agri- and aqua cultural production

In Hanoi City, there are a great number of industries which could be the source of pollution for the city’s atmospheric, aquatic and terrestrial: 274 enterprises and factories, 540 service establishments, 450 production cooperation and 3,350 production establishments Most of them are concentrated in Thuong-Dinh industrial

zone, and Van-Dien and Hai-Ba-Trung area (Marcussen et al., 2006), and some are

located in residential areas Most manufacturers were established in the 1950s with

assistance from China and the former Soviet Union Their plants are old, and do not equip with appropriate wastewater treatment facilities Exhaust emissions from motor vehicles are also a major source of pollutants There are various environmental regulations and standards in Vietnam, but the implementation of these is lacking (Environmental Information Office, Hanoi, 2001)

There are two rivers in Hanoi City (Fig 1.1), the To-Lich and Kim-Nguu Rivers The To-Lich River with 17 km in length originating in West Lake flows through Thuong-Dinh industrial zone to Van-Dien, joining to the Kim-Nguu River Industrial and non-industrial urban wastewater flowing into the To-Lich River amounts to 290,000 m3/day, which accounts for two third of the wastewater produced

in the city (Marcussen et al., 2006) The industry that discharges the wastewater

includes 33 plants, and major ones are Gold-Star rubber, Thanh-Long cigarette, Thanh-Long cigarette, Dai-Kim plastic, and a soap plant The wastewater from these plants is being discharged without any appropriate treatment The irrigation water from the To-Lich River covers 1,361 ha agricultural land in Yen-Hoa, Lang-Ha, and Nhan-Chinh (Cau-Giay) communes, My-Dinh (Tu-Liem), Thanh-Liet (Thanh-Xuan) and Dai-Kim (Thanh-Tri) communes

The Kim-Nguu River with 11 km in length also flows through the densely populated area of Hanoi City The wastewater from the area of 6 km2 is flowing into this river, which amounts 139,000 m3/day, being one third of the wastewater produced

in the city (Marcussen et al., 2006) The main industry that discharges wastewater is

March-8 textile, Mai-Dong mechanical engineering and Hanoi-Win The irrigation water from the Kim-Nguu River covers the agricultural land in Tran-Phu commune (Hai–Ba-Trung) and Yen-So commune (Thanh-Tri); Tu-Hiep and Lien-Minh communes (Thanh- Tri)

y so

l a

:f a c t o r y

w a r t e r , se d i me n t sa mpl e l o c a t i o n

:so i l sa mpl i n g:

Wastewater from households and industries is discharged into the To Lich and Kim Nguu Rivers which today function mainly as the sewage and drainage systems of Hanoi In peri-urban areas of Hanoi, water from those rivers also serves as the source

of water and nutrients for food production in lakes, ponds and heavily irrigated fields However, inappropriate city planning and wastewater management for both industry and household have caused various environmental problems including the heavy metal pollution of surface water, sediments, soils and crops

1.2 SCOPE OF OBJECTIVES

Numerous studies have been made on the heavy metal pollution of water and

sediment in different river systems in over the world (Ricker et al., 1977; Forstner and Muller, 1981; Mark et al., 1982; Yousef et al., 1994; Birch et al., 1996; Fukue et al.,

2006) However, there are very few empirical data for heavy metal contamination of water and river sediment in Hanoi City, Vietnam (Ho and Egashira, 2000) Ho and Egashira (2000) had carried out research only on heavy metal pollution of river sediments while heavy metal pollution of water and the effects of using polluted irrigation water to the quality of soils and crops would not have been mentioned

The objective of this study is to evaluate heavy metal pollution of the water and sediment in the To Lich and Kim Nguu Rivers and its effects on the quality of soils and crops in Hanoi, Vietnam The specific objectives of this study are as follows: (i) To assess the water quality of the To Lich and Kim Nguu Rivers in Hanoi City and its suitability for irrigation water

(ii) To evaluate the heavy metal pollution of sediment in the To Lich and Kim Nguu Rivers

(iii) To evaluate the effects of using polluted irrigation water on the quality of soils and crops in Hanoi, City

(iv) To find out the suitable chemical leaching solutions to eliminate heavy metals from contaminated sediments and soils

1.3 RESEARCH CONTRIBUTIONS

The following list identifies some benefits from research:

(i) Provide obtaining information the heavy metal pollution of the water and sediments in the To Lich and Kim Nguu Rivers Base on these results, we could provide some recommendations to Vietnamese government to set up some policies to reduce discharge of waste water from factories by appropriated wastewater treatment

(ii) Provide a complete evaluation on the effects of using polluted irrigation water from the To Lich and Kim Nguu Rivers on the quality of soil and crops

(iii) Using the suitable chemical leaching solutions to eliminate heavy metals from contaminated sediments and soils

1.4 ORGANIZATION OF THESIS

The thesis consists of six chapters, all of them under the form of scientific papers have already published or submitted

Chapter 1: Presents the scope and objectives of research

Chapter 2: Presents the results from research program to assessment the water quality

of two rivers in Hanoi City and its suitability for irrigation water

Chapter 3: Presents the results from research program to evaluate the heavy metal

pollution from contaminated river sediment in Hanoi City

Chapter 4: Presents the results from the research program to evaluate the impacts of

river pollution on the quality of agricultural soil and vegetables

Chapter 5: Presents the results from research program to evaluate the impacts of

wastewater-irrigated on the quality of paddy soil and rice grain

Chapter 6: Presents the conclusions, research contributions and recommendations for

the future work

1.5 REFERENCES

Alloway, B.J (1995) Cadmium In B.J Alloway (ed.) Heavy metal in soils Blackie

Academic and Professional

Bemond, A (2001) Limits of sequential extraction procedures reexamined with

emphasis on the role of H+ ion reactivity Analytica Chimica Acta, 445: 79-88

Birch, G.F., Evenden, D and Teutsch, M.E (1996) Dominance point source in heavy

metal distributions in sediment of a major Sydney estuary (Australia)

Environmental Geology, 28: 169-74

Bohn, H.L., Mc Neal., B.L and O’Connor, A.G (1985) Soil Chemistry, second ed

Wiley-Inter Science Publications, New York, USA

Brigden, K and Santillo, D (2004) Environment heavy metal concentration arising

from the Xianjin and GP Ni, Cd battery manufacturing facilities Huishou,

Guangdong, China Green Research Laboratories, Department of Biological

Sciences, University of Exeter, UK

Chen, Z., He, M., Sakurai, K., Kang, Y and Iwasaki, K (2007) Concentration and

chemical forms of heavy metals in urban soils of Shanghai, China Soil

Science and Plant Nutrition, 53: 517-529

Chojnacka, K., Chojnacki, A., Gorecka, H and Gorecki, H (2005) Bioavailability of heavy

metal from polluted soils to plants Science of the Total Environment, 337: 175-182

Environmental Information Office, Hanoi 2001 Industrial wastes management in Hanoi,

Vietnam http://www.utoronto.ca/env/ies/ap

Forstner, U and Muller, G (1981) Concentration of heavy metals and polycyclic

aromatic hydrocarbons in rivers sediments Geochemical background, man’s

influence and environmental impact Geojournal, 5(5): 417-432

Fukue, M., Sato, Y., Uehara, K., Kato, Y and Furukawa, Y (2006) Contamination of sediment

and proposed containment technique in a Wood Pool in Shimuzu, Japan In:

Contaminated sediments: evaluation and remediation techniques STP, 1482: 32-43

Hamilton, E.I (1995) State of the art of trace element determinations in plant

matrices; determination of the chemical elements in plant matrices, an

overview Science of the Total Environment, 176: 3-14

Ho, T.L.T and Egashira, K (2000) Heavy metal characterization of river sediment in Hanoi,

Vietnam Communication in Soil Science and Plant Analysis, 31: 2901-2916

Klank, L.T., Vuong, T A., Phung, D C and Dalsgaard, A (2006) KVL and NIHE

partner food quality report for Hanoi and Phnom Penh microbiological part In

“Food safety of aquatic plants and fish raised in wastewater-fed ponds”

Production in Aquatic Peri - Urband Systems in Southeast Asia INCO:

International Scientific Cooperation projects (1998-2002)

Marcussen, H., Jorgensen, K., Holm, P.E., Brocca, D., Simmons, R W and

Dalsgaard A (2006) Elemental content and food safety of water spinach

(Ipomoea aquatica Forssk.) cultivated with waster in Hanoi, Vietnam In

“Food safety of aquatic plants and fish raised in wastewater-fed ponds”

Production in Aquatic Peri urban Systems in Southeast Asia, INCO: International Scientific Cooperation Projects

Mark, E., Hart, B.T and Beckett, R (1982) Trace metals in sediment from the Yarra

River Australia Freshwater Resources, 33: 761-778

Mc Grath, S P (1987) Long term studies of metals transfers following applications

of sewage sludge In P J Coughtrey, M.H Martin, and M H Unsworth

(Eds.), Pollutant transport and fate in ecosystems Special Publication No 6

of the British Ecological society (pp 301-317) Oxford: Blackwell

Nolan, A L., Zhang, H and Mc Laughlin, M J (2005) Prediction of Zn, cadmium,

lead, and copper availability to wheat in contaminated soils using chemical speciation, diffusive gradients in thin films, extraction, and isotopic dilution

techniques Journal of Environmental Quality, 34: 496-507

Mandaokar, S S., Dharmadhikari, D M and Dara, S S (1994) Retrieval of heavy metal ions

from solution via fertilization Environmental Pollution, 83: 277-282

Oliver, M.B (1997) Soil and human health: a review European Journal of Soil

Sciences, 48: 573-592

Rickert, D.A., Kennedy, V C., Mckenzie, S.W and Hines, W.G (1977) A synoptic

survey of trace metals in bottom sediments of the Willamette River, Oregon, U.S Geol Surv Circ, 715-F

Salemaa, M., Vanha, M I and Derome, J (2001) Understudy vegetation along a heavy metal

pollution gradient in SW Finland Environmental Pollution, 112: 339-350

Venditti, D., Durecu, S and Berthelin, J (2000) A multidisciplinary approach to

assess history, environmental risks, and remediation feasibility of soils contaminated by metallurgical activities-part A: chemical and physical

properties of metals and leaching ability Archives of Environmental

Contamination and Toxicology, 38: 411-420

Yousef, Y.A., Lin, L.Y., Lindeman, W and Jacobsen, T H (1994) Transport of

heavy metal through accumulated sediment in wet ponds Science of the Total

Environment, 146/147: 485- 491

CHAPTER 2 ASSESSMENT OF THE WATER QUALITY OF TWO RIVERS IN HANOI CITY AND ITS SUITABILITY FOR IRRIGATION WATER

Abstract

This chapter describes the chemical properties of waters from the To Lich and Kim Nguu Rivers focusing on heavy metal pollution and the suitability of water quality for irrigation Waters from the rivers were heavily polluted with organic matter and heavy metals such as Pb, Cu, Zn, Cr, Cd and Ni Dissolved oxygen, chemical oxygen demand, and total suspended solids, and the concentrations of all heavy metals exceeded the Vietnamese standard for surface water quality in all investigated sites The concentrations of some heavy metals such as Cu, Cd, Cr and

Ni were over the internationally recommended WHO maximum limits for irrigation water A wide variation in heavy metal concentrations of waters due to metal types is the result of wastewater discharged from different industrial sources

Key words Heavy metals, Stream water, Irrigation, Industry

- This chapter was published as an article in the Journal of the International Society

of Paddy and Water Environment Engineering under the reference:

Nguyen Thi Lan Huong, Masami Ohtsubo, Loretta Li and Takahiro Higashi and Motohei Kanayama 2008 6(3) (Received 14 May 2007; accepted 11 March 2008, published online 20 march, 2008)

- A part of this chapter was published as an article in the Journal of Agricultural Faculty,

Kyushu University under the reference:

Nguyen Thi Lan Huong, Masami Ohtsubo, Loretta Li and Takahiro Higashi 2007 52 (1): 141-146

et al., 2003; Nguyen et al., 2007)

Water pollution is harmful not only to fish breeding and agricultural products, but also to public health in surrounding areas Of the pollutants, heavy metals can endanger public health by being incorporated into food chain Heavy metals are not biodegradable and tend to accumulate in the sediments of waterways in association with organic and inorganic matter in the sediments In the present study, we examined the chemical properties of stream waters to assess mainly heavy metal pollution and its suitability for irrigation water

2.2 METHODOLOGY

2.2.1 Materials

Eight surface water samples were collected at 8 locations on December 3 to 6

of 2005 (Fig 2.1 and Table 2.5) There are two seasons (rainy and dried seasons) in the Hanoi, Vietnam The time for taking samples is dried season, with lower level water in the river than other one

KIM NGUU RIVER

BUOI MARKET

WATER SAMPLING FACTORY

AGRICULTURAL LAND

2 km

Yen Hoa

Lang Ha Nhan Chinh

Tran Phu

23

sit es Fact or y

Figure 2.1 Location of sampling sites and factories

2.2.2 Methods

The pH of water was measured with a pH meter (HM 30 G Horiba) Electric conductivity (EC) was determined using conductivity meter (CM 20S TOA) Dissolved oxygen (DO) was measured with Yellow Spring YS1 58 Chemical oxygen demand (COD) was determined by Kali Manganese methods (KMnO4) For total suspended solid (TSS), the original water samples were filtered using glass filtering paper, and then the solid was dried at 1000C and the mass of the solid was measured Cation and anion concentrations in water were measured for filtered water samples with ion chromatograph (DIONEX DX-100) Water-soluble and total heavy metal concentrations were determined for filtered and non-filtered water samples, respectively Heavy metals in the water samples were analyzed with atomic absorption spectrophotometer (AAS – Solar S2 Thermo electronic cooperation) The determinations were made in duplicate and the relative deviations of the duplicate values were usually less than 5%

2.3 RESULTS AND DISCUSSION

2.3.1 Chemical properties of water

The water qualities determined are summarized in Table 2.1 The pH ranged between 6.8 and 11 The pH for WS 2, 3 and 6 was much higher than the Vietnamese standard (pH 5.5-9) for surface water (TCVN 5942-1995; MOSTE of Vietnam, 2002) The EC ranged from 0.66 to 0.78 mS/cm The DO exhibited extremely low values of 0.1- 0.7 mg/L, which does not meet the Vietnamese requirement (≥2 mg/L) for surface water The COD and TSS were in the range of 106- 184 mg/L and 200 - 350 mg/L, respectively, which exceed the standard TCVN (5942-1995) (MOSTE of Vietnam, 2002) by 3-5 times

Table 2.1 Chemical properties in the waters of the To Lich and Kim Nguu Rivers

** TCVN 5942-1995 B (MOSTE of Vietnam, 2002): Category B: applied to the surface water used for the purpose other than domestic

water supply, including irrigation water

Table 2.2 Correlation coefficient between chemical properties of waters

Cation concentrations were similar among the samples for cation types, while anion concentrations were fairly different among the samples for all anion types Fluorine was detected only for WS 6, 7 and 8 The concentrations of F for these samples and the NO3 concentrations for WS 1 and WS 2 exceeded the standard of surface water

Table 2.2 shows the correlation coefficients between the chemical properties

of the water samples The correlation coefficient was significant between DO and COD at 1 % level, but was not significant for other combinations of the chemical properties

2.3.2 Heavy metal pollution assessment

Table 2.3 shows the water soluble and total heavy metal concentrations in the water samples The averages of the water soluble metal concentrations for the water samples subjected to filtering to remove suspended solid were in the order of Cr > Cu

> Pb > Zn > Ni > Cd The average total metal concentrations of the samples containing suspended solids were in the order Cr > Pb > Cu > Zn > Ni > Cd

The total heavy metal concentrations for Cd, Cr and Pb exceeded the permissible level of the surface water standard (TCVN 5942-1995B: MOSTE of Vietnam, 2002) The concentrations of Cu for WS 2, 3, 5 and 7 were also over the level of the standard in all samples The concentrations of Ni and Zn were well within the permissible level

To compare the total and water-soluble metal concentrations, the relationships between the two parameters are shown in Fig 2.2 For the metals other than Cd, the total metal concentrations were higher than the water-soluble metal concentrations respectively The mass of heavy metal, equivalent to the difference between the total and water-soluble metal concentrations, is retained by suspended solid The averages

Table 2.3 Heavy metal concentrations in waters from the To Lich and Kim Nguu Rivers

* pH was measured at lab

** TCVN 5942-1995 B (MOSTE of Vietnam, 2002): Category B: applied to surface water used for purpose other than domestic

water supply, including irrigation water

Figure 2.2 Relationships among total, water-soluble concentrations and metal retained by suspended solid

Ni Pb Zn

massed of heavy metals retained by suspended solids in the samples are as follows: Cu = 2.61 g/kg, Zn = 2.87 g/kg, Pb = 2.49 g/kg, Cd = 0.03 g/kg, Cr = 4.13 g/kg, Ni = 0.22 g/kg (Table 2.4) The retention of the heavy metals by suspended solid would be due to the complexation of metals with organic and inorganic ligands The mechanisms proposed for the immobilization of metals by organic matter include the enhanced metal adsorption through increased surface charge, increase in the formation of organic and inorganic metals complexes, the precipitation of metals and the reduction

of metals from mobile forms which higher valence to immobile form with lower valence (Bolan and Duraisamy, 2003)

To assess how the effluents from industrial plants located in the areas of the sampling sites affect water quality of the To Lich and Kim Nguu Rivers, information

on the plants in each area is presented in Table 2.5 along with the total heavy metal concentrations of the water samples cited from Table 2.3 The extremely high Cd concentration of 1.1 mg/L was found for WS 3, which would be due to effluents from plastic and machine plants in Thuong Dinh industrial zone The Cr concentrations were in high in all water samples, and the highest concentration (5.96 mg/L) was found in WS 7, this would be attributed to effluents from the machine plant in Hai Ba Trung industrial zone The high concentration of Cr in WS 1 would have been caused

by discharged wastewater from the leather factory, because Cr is present as a component in leather products (Brigden and Santillo, 2004)

The high concentrations of Cu and Pb were found in WS 2 (Cu = 1.66 mg/L) and WS 7 (Cu = 1.07 mg/L and Pb = 1.74 mg/L) Wastewater from the plants in Thuong Dinh and Hai Ba Trung industrial zones is flowing into these sites The Cu that accumulated in sediment is mainly derived from textile and shoes industrial

sectors (Marcussen et al., 2006)

Table 2.4 Heavy metal concentrations in suspended solids (g/kg)

The source of Pb in all sites would be due to the pollutants derived from transportation activities as well as manufacturing processes The particulates on the stress contaminated with Pb due to emission from increasing motor vehicle are still the main source of Pb in Hanoi City, through emission has been reduced drastically

by phasing out of tetra-ethyl lead as a fuel additive The dominant source for the Pb in

stream water was shown to emission of Pb aerosol from gasoline vehicles (Turer et al.,

2000; Preciado and Li, 2005)

Brigden and Santillo (2006) indicated that Cd, Ni and Zn are used in a battery manufacturing process, and water and sediment in a drain are heavily contaminated with those heavy metals The highest Zn concentrations for WS 6 (1.87 mg/L) can be ascribed to effluents from battery plant in Van Dien industrial zone The concentrations of Cd and Ni were rather low for most water samples other than WS 3

Table 2.5 Information on the industry in the areas of the water sampling sites

and the total heavy metal concentrations of water

2.3.3 Suitability for Irrigation Water

Currently water streams from the To Lich and Kim Nguu Rivers are being supplied to the agricultural land of various communes: Yen Hoa, Lang Ha and Nhan Chinh Communes in Cau Giay; My Dinh Commune in Tu Liem; Thanh Liet, Dai Kim,

Yen So, Tu Hiep, Tam Hiep and Lien Minh Communes in Thanh Tri; and Tran Phu Commune in Hai Ba Trung

The irrigation water standard for heavy metals (WHO, 1989) is shown in Table 2.3 The total heavy metal concentration in water was compared with the irrigation water standard The total heavy metal concentrations in all sites exceeded the permissible level for Cd, Cr, Cu and Ni while were within the permissible level for Pb and Zn Particularly the total Cr concentration in the water samples was 4 ÷ 50 times as high as the permissible concentration (0.1 mg/L)

The excess as high trace elements in irrigation water can restart the growth and metabolic activities of crop plants The primary routes of exposure of humans to trace elements in soil are through food chain transfer and by direct ingestion of soil particles Documented cases of chronic adverse health effects due to trace element exposure through food chain transfer or direct ingestion of soil are more numerous Toxic elements, which accumulated in the soil, move into edible parts of crops,

posing considerable health risk to humans and animals (Pillay et al., 2003)

2.4 CONCLUSIONS AND RECOMMENDATION

Stream waters in the To Lich and Kim Nguu Rivers are heavily polluted with organic mater and heavy metals such as Pb, Cu, Zn, Cr, Cd and Ni The DO, COD and TSS of the water as organic matter indexes and the concentrations of all heavy metals exceed the Vietnamese standard for surface water quality (TCVN 5942-1995 B: MOSTE of Vietnam, 2002) in all investigation sites The concentrations of some of the heavy metals such as Cu, Cd, Cr and Ni exceed the WHO maximum acceptable limits for irrigation water A wide variation in heavy metal concentration due to metal types is result from wastewater discharged from different industrial sources