Investigation the heavy metal contents in surface water and sediment collected in ThadLuang Marsh (Lao PDR)

Phetdalaphone BOUTTAVONG 2009-2011 VIETNAM NATIONAL UNIVERSITY, HANOI VNU UNIVERSITY OF SCIENCE PHETDALAPHONE BOUTTAVONG INVESTIGATION THE HEAVY METAL CONTENTS IN SURFACE WATER AND SEDIMENT COLLECTED IN THADLUANG MARSH (LAO PDR) MASTER THESIS HANOI, 2011 Phetdalaphone BOUTTAVONG 2009-2011 VIETNAM NATIONAL UNIVERSITY, HANOI VNU UNIVERSITY OF SCIENCE PHETDALAPHONE BOUTTAVONG INVESTIGATION THE HEAVY METAL CONTENTS IN SURFACE WATER AND SEDIMENT COLLECTED IN THADLUANG MARSH (LAO PDR) MASTER THESIS Supervisor: Assoc Prof PhD Ta Thi Thao HANOI, 2011 Phetdalaphone BOUTTAVONG 2009-2011 Abstract In Vientiane, water and sanitation management in the urban area is experiencing stagnant pollution Unsanitary conditions and threat of seasonal pollution in selected spots is likely to occur and increase with the growing urban population The sanitation system entails an on-site disposal of human waste without introduction of full water-borne sewerage with treatment facility and safe disposal arrangement The majorities of households relies on water flush latrines and are connected to a pit or chamber for containment of excreta However, due to the low permeability of the soil and the high groundwater table around Vientiane, many soak-a-ways fail to operate effectively resulting in discharge of sewage from tanks into drainage channels or low lying areas This pollution leads to effluent overflows, environmental degradation and health hazards For the sake of assessment in what extent is water polluted, an analytical method with high sensitivity and the capability and providing a good accuracy and precision should be used Atomic absorption spectroscopy (AAS) is a spectroanalytical procedure for the qualitative and quantitative determination of chemical elements employing the absorption of optical radiation (light) by free atoms in the gaseous state In analytical chemistry the technique is used for determining the concentration of a particular element (the analyte) in a sample to be analyzed The technique makes use of absorption spectrometry to assess the concentration of an analyte in a sample My study focuses on heavy metals content in surface water and sediment collected in ThadLuang Marsh in Vientiane Capital City Providing an overview about alarmingly polluted situation, this research based on determination of Copper, Lead, Cadmium and Zinc by Flame – Atomic absorption spectroscopy Phetdalaphone BOUTTAVONG 2009-2011 Acknowledgements I would like to thank, DAAD, Deutscher Akademischer Austauschdienst (German Academic Exchange Service) and Technich University Dresden for providing the scholarship of the Master’s program My sincere thanks also due to the Dean of faculty Environmental of sciences in National University of Lao P.D.R for the kind permission offered me to study Thank Assoc Prof Dr Ta Thi Thao - my supervisors for encouragement, constructive guidance's I would like to express the profound gratitude and the great appreciation to my advisor Prof Bernd Bilitewski for his excellent guidance, excellent encouragement and valuable suggestions throughout this study Special appreciation is extended to Prof Dr Nguyen Thi Diem Trang and Prof Dr Do Quang Trung committee members for their valuable recommendation and dedicated the valuable time to evaluate my work and my study during being in Vietnam During studying in Hanoi University of Science, I felt very lucky, it give me the opportunity to have lots of good friends, good memories, so I would like to say thanks and pleasure to meet all of you Even though we came from different countries, we can make friend together I hope and wish that I would work together and meet each other again in some conferment Finally I would like to express deep appreciation to my lovely family and relatives for their love, kind support, and encouragement for the success of this study This thesis is dedicated for you Phetdalaphone BOUTTAVONG 2009-2011 Contents List of Figures List of Tables List of Abbreviations INTRODUCTION 10 CHAPTER 1: OVERVIEW OF WATER AND SEDIMENT POLLUTION IN THADLUANG MARSH 10 1.1 Topography of ThadLuang marsh 13 1.2 Present status of water and sediment pollution in ThadLuang marsh 14 1.3 Toxicity of Cadmium Cd, Copper Cu, Lead Pb, Zinc Zn 16 1.3.1 Cadmium Cd 16 1.3.2 Copper Cu 17 1.3.3 Lead Pb 18 1.3.4 Zinc Zn 20 1.4 Analytical methods for determination of heavy metals in water and sediment samples 22 1.4.1 Electrochemical methods 22 1.4.2 Spectrophotometric methods 24 CHAPTER 2: EXPERIMENTS 28 2.1 Research Objects and research contents 28 2.1.1 Research objects 28 2.1.2 Research contents 28 2.2 Chemicals and Apparatus 29 2.2.1 Chemicals 29 Phetdalaphone BOUTTAVONG 2009-2011 2.2.2 Apparatus 29 2.2.3 Equipments 30 2.3 Sampling and Sample Preparation 30 2.3.1 Study Area 30 2.3.2 Sampling and sample preparation 35 2.3.3 Sediment samples 35 2.4 Analytical methods for determination of Cu, Pb, Cd, Zn 36 2.4.1 Flame atomic absorption spectroscopy method (F-AAS): determination of heavy metal content in sediment samples 36 2.4.2 Inductive couple plasma – mass spectrophotometry (ICP-Ms) for the determination of heavy metal contents in surface water samples 40 2.4.3 Quality control of analytical methods 43 CHAPTER 3: RESULTS AND DISCUSSION 45 3.1 Optimizations of some chemical factors influencing to absorbance in F- AAS method 45 3.1.1 Study the effects of sample matrix and matrix modifier to F-AAS 45 3.1.2 Calibration curves of Pb, Cd, Zn and Cu measurements 49 3.1.3 Limit of detection (LOD) and Limit of quantitation (LOQ) 53 3.1.4 Effect of interferences to the determination of Pb, Cd and Cu, Zn by FAAS 54 3.2 Determination of Pb, Cu, Zn, Cd in surface water samples using ICP-MS 57 3.2.1 Calibration curves for the determination of Cu, Zn, Pb and Cd in water samples 57 3.2.2 Method validation 59 3.3 Total concentrations of Cu, Pb, Cd, Zn in surface water and sediment of ThadLuang marsh 60 3.3.1 Water sample: 60 3.3.2 Sediment sample 60 3.4 Application of GIS to find out spartial distribution of heavy metals 64 Phetdalaphone BOUTTAVONG 2009-2011 CHAPTER 4: CONCLUSION ….66 REFERENCE 65 List of figures Figure 1.1: Target Villages around ThadLuang Marsh Figure 2.1: Spectrometer atomic absorption novAA 6800, Shimazhu Figure 2.2: The map of Thatluang marsh showing water sampling sites Figure 2.3: The map of Thadluang marsh showing sediment sampling sites Figure 2.4: Operation principle of an atomic absorption spectrometer Figure 2.5: Block diagram of atomic absorption spectrometer Figure 2.6: Instrumentation for low-resolution ICP-MS Figure 3.1: The investigation of linear ranges for the determination of Pb, Cd, Zn and Cu using F-AAS Figure 3.2: The calibration curves for the determinations of Pb, Cd, Zn and Cu in standard solutions Figure 3.3: Calibration curves for the determination of Cu, Cd, Pb and Zn using ICPMS Figure 3.4: The Map of water quality of Thadluang Marsh Figure 3.5: The Map of sediment quality of Thadluang Marsh Phetdalaphone BOUTTAVONG 2009-2011 List of tables Table 1.1: Some data published on pollution in ThadLuang marsh Table 2.1: Characteristics of the sampling points in Thadluang marsh Table 2.2: Characteristics of the sediment points in Thadluang marsh Table 2.3: The optimal conditions of F-AAS for measuring Pb, Cd, Zn, Cu Table 2.4: The experimental conditions for determination of Cu, Pb, Cd and Zn using ICP- MS techniques Table 3.1: Investigation of HNO3 and NH4CH3COO effects on analysis of Pb, Cd, Cu and Zn Table 3.2: Two - way ANOVA table for evaluating effects of HNO3 and NH4CH3COO Table 3.3: Influence of types of acid media HCl, HNO3 and H2SO4 effects on Cu2+ and Pb2+ analysis Table 3.4: The absorbance of each metal atom (after subtracting the absorbance of the blank solution) vs their concentrations Table 3.5: The absorbance of each heavy metal standard solutions in the linear range of concentrations Table 3.6: LOD and LOQ of the determination of Pb, Cd, Zn and Cu using F-AAS method Table 3.7: Result of errors and repeatability of the measurements Table 3.8: Accuracy and recovery of CRM using FAAS and ICP-MS Table 3.9: The concentration of Pb, Cd, Zn, Cu in surface water samples of ThadLuang Marsh (g/L) Table 3.10: Heavy metal content (mg/kg) in sediment collected in Thadluang marsh Table 3.11: Proposed Surface Water Quality standard Phetdalaphone BOUTTAVONG 2009-2011 List of abbreviations Lao PDR The Lao People’s Democratic Republic EDTA Ethylene-diamine-tetracetic acid DME Dropping mercury electrode SMDE Static mercury drop electrode AES Atomic emission spectroscopy F-AAS Flame Atomic absorption spectroscopy ICP-Ms Inductive couple plasma – mass spectrophotometry ANOVA The analysis of variance LOL The limit of linearity LOD Limit of detection LOQ Limit of quantitation Phetdalaphone BOUTTAVONG 2009-2011 INTRODUCTION The Lao People’s Democratic Republic (Lao PDR) is a small landlocked and sparsely populated country in the South East Asia Laos is characterized by two main geographical zones: the central plains along the Mekong River and the mountainous regions to the north, east and south Lao PDR has a land area of 236,800 square kilometers (sq km.) It is long and slender, the length from north to south is nearly 1,000 kilometers and the width has only 150 kilometers to 400 kilometers [STEA, 2004] The total population is approximately 5,621,982 people, in which women accounted for 51%, according to the 2005 population and housing census The population density of the country is around 24 people per hectare which is the lowest population densities in Asia 39% of Lao population is classified as poor and 36% are under poverty line [MRC, 2006] Their living condition depends on nature, hunting wildlife, foraging for forest products and practicing slash and burn cultivation for their crops with a low profit in order to survive Lao PDR has rich water resources, mainly good quality fresh water The amount of average water flow in the Mekong and its tributaries amount to about 8,500 m3/s Currently most of the water occurs in the agricultural sector, for instance, irrigation, fisheries, plantations and livestock watering 60 percent of urban population and 51 percent of rural population has access to clean water [Draft Agreement, March 2009] The total of annual water flow in Lao PDR is estimated at 270 billion cubic meters, equivalent to 35% of the average annual flow of the whole Mekong Basin The monthly distribution of the flow of the rivers in Lao PDR closely follows the pattern of rainfall: about 80% during the rainy season (May-October) and 20% in the dry season, from November to April For some rivers in the central and southern parts of the country (particularly Se Bang Fai, Se Bang Hieng and Se Done) the flow in the dry season is less: around 10 to 15% of the annual flow [Agricultural Statistics 10 Phetdalaphone BOUTTAVONG 2009-2011 + Ai: The value of the measured intensity of absorption when on interference present (Abs) + At: Absorption intensity value found when the other analytes being exist (Abs) The precision of measurements was determined by the quantity of S2 and value of RSD (%) and were calculated as follows: (𝐴 𝑡 −𝐴 𝑖 )2 𝑆 = 𝑆 = 𝑆2 𝑛 −1 %𝑅𝑆𝐷 = 𝑆 𝐴 𝑡𝑏 100 Where: + Atb: The average absorbance + n: number of measurements + S or SD: standard deviation + %RSD : relative standard deviation The experimental results is illustrated in table 3.7 Table 3.7: Result of errors and repeatability of the measurements Pb (2ppm) Abs %X Ai = Pb Other element (1ppm) At = Pb + Cd Abs 0.02786 %X 0.02895 3.9 AtA= Pb + Zn = Cd 0.02819 0.3681 1.2 At == Pb Cu A Cd++ Pb t 0.02984 0.3988 3.9 8.3 At = Cd + Zn 0.4164 Element Cd (2ppm) (1ppm) i 13.1 55 RSD % RSD % 3.07 6.13 Phetdalaphone BOUTTAVONG 2009-2011 At = Cd+ Cu 0.4232 14.9 Abs %X Zn (2ppm) Other RSD % element (1ppm) Ai Zn 0.09381 0.92 At = Zn + Pb 0.09548 1.8 At = Zn + Cd 0.09500 1.2 At = Zn + Cu 0.0958 2.1 Cu (2ppm) Other element RSD % Abs %X (1ppm) 56 Phetdalaphone BOUTTAVONG 2009-2011 Ai = Cu 0.02143 At = Cu + Pb 0.02214 3.3 At = Cu + Cd 0.02391 11.6 At = Cu + Zn 0.02226 3.8 4.69 The obtained results showed that the relative error followed the Gaussian distribution law The beginning and the end of the linear error of greater suffering in the concentration between the baseline errors is minimal But all these errors are less than the allowable limit of the analysis of ultra-traces is 15% In addition, many other cations not have any affects on the absorbance of Cu, Pb, Zn and Cd The fact shows that the samples contain these cations’ concentration much smaller than the concentration of the elements investigated In a word, there is no other cation in the samples effects directly on the analytic results 3.2 Determination of Pb, Cu, Zn, Cd in surface water samples using ICPMS In river water samples, the concentrations of four heavy metals (Pb, Cu, Zn, Cd) are usually lower than the limit of detection of F-AAS method Therefore, ICPMS techniques with very low limit of detection, and high selective and simultaneous determination need to be applied to analyze All the experimental conditions of ICPMS method were followed by instructors and manufacturer and were applicable as the previous studies at Chemical Faculty, HUS 3.2.1 Calibration curves for the determination of Cu, Zn, Pb and Cd in water samples Four standard solutions of each analyte including Cu, Zn, Pd and Cd in 1% HNO3 media were prepared and the analytical signal (cps) were obtained at experimental conditions (part 2.4.2.2) Because of the large dynamic range with the range of concentration changing from ppt to ppm, it is not necessary to investigate Based on the experimental results, the calibration curves of four metals were investigated and illustrated in figure 3.3 57 Phetdalaphone BOUTTAVONG 2009-2011 60000 180000 160000 50000 140000 40000 100000 Parameter Value Error -B 843.71621 7.29638 80000 60000 40000 Intensity (cps) Intensity(cps) 120000 R SD N P -0.99979 1647.21236