Investigation the heavy metal contents in surface water and sediment collected in thadluang marsh lao PDR

VIETNAM NATIONAL UNIVERSITY, HANOI VNU UNIVERSITY OF SCIENCE PHETDALAPHONE BOUTTAVONG INVESTIGATION THE HEAVY METAL CONTENTS IN SURFACE WATER AND SEDIMENT COLLECTED IN THADLUANG MASTE

VIETNAM NATIONAL UNIVERSITY, HANOI

VNU UNIVERSITY OF SCIENCE

PHETDALAPHONE BOUTTAVONG

INVESTIGATION THE HEAVY METAL CONTENTS IN SURFACE WATER AND SEDIMENT COLLECTED IN THADLUANG

MASTER THESIS

HANOI, 2011

VIETNAM NATIONAL UNIVERSITY, HANOI

VNU UNIVERSITY OF SCIENCE

PHETDALAPHONE BOUTTAVONG

INVESTIGATION THE HEAVY METAL

CONTENTS IN SURFACE WATER AND SEDIMENT

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

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

Contents

List of Figures 7

List of Tables 8

List of Abbreviations 9

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

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

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

Figure 3.4: The Map of water quality of Thadluang Marsh

Figure 3.5: The Map of sediment quality of Thadluang Marsh

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

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

List of abbreviations

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

[April 2005] The rivers outside the Mekong Basin flow through Viet Nam into the South China Sea These rivers are Nam Ma, Nam Sam, and Nam Neune The limited information on these rivers restricts assessment of their potential

Most of the water use occurs in the agricultural sector such as irrigation, fisheries, plantations and livestock watering In addition the water is used for hydro-power; the country has the potential to produce 23,000 megawatts of electricity Currently 5% of that capacity has been exploited [Would Back, 2007] The plenteous supply of water

in Lao PDR, especially in the rainy season, provides good condition for water transport, industrial development and water supply Sixty percent of urban population and 51 % of rural population has access to clean water

Currently there are some problems related to waste and polluted water in major urban areas from varied community use (residential density, hotels, hospitals and entertainments centers) In addition there is water pollution from agricultural and industrial sectors, including mineral exploitation This is not a major problem now, but the problem could escalate The degradation of natural water and water catchments from sedimentation, land erosion and drying out continues

However, as continued development takes place in all of these areas, increasing scarcity and competition for water can be expected Increasing impacts of development on water quality and on human health and the natural environment will also take place Finally, floods and drought can have serious negative impacts and may, in fact, increase as climate change takes place

Vientiane Capital is located on an alluvial plain along the left bank of Mekong River east to west The area of Vientiane is about 3,920 km2 and the elevation of the ground ranges from 160 m to 170 m above the sea level The city comprises 9 districts; Chanthabuly, Hadxayfong, Meungparkngum, Naxaithong Sangthong, Sikhottabong, Sisattanak, Saysettha and Xaythany The population is around 672,912 people The area designated for urbanization extends along the left bank of Mekong River and occupies an area of 210 km2 [JICA, 2009] For Thadluang wetland, its water quality

is a part of the water quality-monitoring project of Mekong Secretariat, in the vicinity

of Vientiane Capital City Main problems found are wastewater and sewage (from the city area) discharged into the marsh

Especially, no sooner do many factories appear and develop increasing fast than water is polluted by heavy metals is over allowable limit Owing to not taking part in

biochemical process, heavy metals such as Cd, Pb, Zn, Cu … are accumulated in human body, which leads to harmfulness for organism The fact that water is polluted

by heavy metal is often seen in rivers near industrial area, big cities and minerals exploiting area The main reason leading to heavy metals pollution is pouring into water environment a large amount of industrial and untreated wastewater Pollution

by heavy metals accumulated through foods directly into organism has negative effects on life environment In order to reduce consequence of this problem, it is necessary to cultivate measures of water treatment

CHAPTER 1: OVERVIEW OF WATER AND SEDIMENT

POLLUTION IN THADLUANG MARSH

1.1 Topography of Thad Luang marsh

The ThadLuang Marshland is the largest remaining wetland in Vientiane Municipality, located on the eastern edge of the capital city of Lao PDR The marsh itself is approximately 20 km2 and is a part of the ThadLuang Basin drained from Vientiane City and surrounding areas A large portion of the wetland has been converted to rice cultivation although changes in water regimes have resulted in annual floods and cultivation has been limited to between 700 - 1000 ha (approximately half of the wetland area) in recent years The remaining area is covered with permanent and seasonal aquaculture ponds, shrub and grassland, and peat land [NUOL, March, 2002] Water draining into the ThadLuang Marshland comes primarily from irrigation canal at the Donnokkoom rice field, Hong Ke and Hong Xeng stream, which collects its water from drainage canals running throughout Vientiane Water running out of the marsh follows Houay Mak Hiao River dumping into the Mekong 64 km south east of Vientiane

Based on a recent government survey in the That Lung area, about 90 percent

of households around ThadLuang Marsh are classified as poor and only 10 percent of households as relatively better off category Because of the structure of rural employment, the livelihoods of households around ThadLuang Marsh are highly depended upon the ThadLuang marsh, and the water resources availability at the marsh This is because agriculture and sale of agriculture produce are the primary income generating activity for over 70 % of households living around the ThadLuang marsh About 7 percent of the total households there are without a primary form of income from agriculture (farming), and it is likely that they rely heavily on collecting fish and aquatic produce from the marsh area [STO, 2009] Therefore, being one of main reasons leading to poverty, water and sediment pollution in ThadLuang marsh affect significantly on life of people here

Figure 1.1.Villages around ThadLuang Marsh

1.2 Present status of water and sediment pollution in ThadLuang marsh

ThadLuang Marsh receives domestic sewage discharge from a large proportion of Vientiane city by way of several canals While Vientiane has a sewerage system, there is currently no functioning waste treatment facility near the urban area Sewage is either hauled to a waste treatment plant 17 km outside of the city limits or, more commonly, discharged into natural water bodies, either as raw wastes or as seepage from septic tanks Sewerage and sanitation systems rely on the infiltration of wastewater into the ground However due to the low soil permeability and the high groundwater table in Vientiane, many soak ways fail to operate efficiently meaning that sewage is discharged from tanks and drains directly into urban wetlands As a result of considerable quantity of household waste and sewage

is discharged into Nong Chang, and then flows into ThadLuang Marsh before entering the Mekong Textile, detergent and paper plants discharge directly into open drains without any treatment, and contribute wastewaters into ThadLuang Marsh

There are two tanneries although the larger of these has sophisticated treatment facilities, in practice wastes bypass these and are discharged untreated The brewery

on the southern shore of ThadLuang passes waste through an oxidation pond

Because of the importance of ThadLuang with issues directly relating to Vientiane environment, it is irrefutable that researching water pollution in ThadLuang is necessary and must be done immediately Some data published on pollution in ThadLuang marsh is shown in table 1.1

Table 1.1: Some data published on pollution in ThadLuang marsh

(STEA, 2000)

to this table, pH, BOD, Ammonia nitrogen (NH3-N) and PO

4-P parameters are much higher than standard while Dissolve Oxygen (DO) and Nitrate-Nitrogen (NO

3-N) are

lower There is sound that water pollution appears compared to Surface Water Quality Standard in Lao PDR Also, by the fact that it exist wastewater and sewage (from the city area) discharged into the marsh Especially, no sooner do many factories appear and develop increasing fast than water is polluted by heavy metals is over allowable limit

1.3 Toxicity of Cadmium Cd, Copper Cu, Lead Pb, Zinc Zn

1.3.1 Cadmium Cd

The most dangerous form of occupational exposure to cadmium is inhalation

of fine dust and fumes, or ingestion of highly soluble cadmium compounds Inhalation of cadmium-containing fumes can result initially in metal fume fever but may progress to chemical pneumonitis, pulmonary edema, and death [Ayres, Robert

U, 2003]

Cadmium is also an environmental hazard Human exposures to environmental cadmium are primarily the result of fossil fuel combustion, phosphate fertilizers, natural sources, iron and steel production, cement production and related activities, nonferrous metals production, and municipal solid waste incineration However, there have been a few instances of general population toxicity as the result of long-term exposure to cadmium in contaminated food and water In the decades leading up

to World War II, Japanese mining operations contaminated the Jinzū River with cadmium and traces of other toxic metals.[National Research Council (U.S.), 1969) ]

As a consequence, cadmium accumulated in the rice crops growing along the riverbanks downstream of the mines Some members of the local agricultural communities consuming the contaminated rice developed itai-itai disease and renal abnormalities, including proteinuria and glucosuria

The victims of this poisoning were almost exclusively post-menopausal women with low iron and other mineral body stores Similar general population cadmium exposures in other parts of the world have not resulted in the same health problems because the populations maintained sufficient iron and other mineral levels Thus, while cadmium is a major factor in the itai-itai disease in Japan, most researchers have concluded that it was one of several factors Cadmium is one of six substances banned by the European Union's Restriction on Hazardous Substances (RoHS) directive, which bans certain hazardous substances in electrical and

electronic equipment but allows for certain exemptions and exclusions from the scope of the law

Although some studies linked exposure to cadmium with lung and prostate cancer, there is still a substantial controversy about the carcinogenicity of cadmium More recent studies suggest that arsenic rather than cadmium may lead to the increased lung cancer mortality rates Furthermore, most data regarding the carcinogenicity of cadmium rely on research confounded by the presence of other carcinogenic substances

Tobacco smoking is the most important single source of cadmium exposure in the general population It has been estimated that about 10% of the cadmium content

of a cigarette is inhaled through smoking The absorption of cadmium from the lungs

is much more effective than that from the gut, and as much as 50% of the cadmium inhaled via cigarette smoke may be absorbed [Jarup, L (1998)]

On average, smokers have 4-5 times higher blood cadmium concentrations and 2 - 3 times higher kidney cadmium concentrations than non - smokers Despite the high cadmium content in cigarette smoke, there seems to be little exposure to cadmium from passive smoking No significant effect on blood cadmium concentrations has been detected in children exposed to environmental tobacco smoke

Cadmium exposure is a risk factor associated with early atherosclerosis and hypertension, which can both lead to cardiovascular disease

1.3.2 Copper Cu

Copper toxicity refers to the consequences of an excess of copper in the body Copper toxicity can occur from eating acid food that has been cooked in un-coated copper cookware, or from exposure to excess copper in drinking water or other environmental sources

Copper in the blood exist in two forms: bound to ceruloplasmin (85–95%) and the rest "free" loosely bound to albumin and small molecules Free copper causes toxicity as it generates reactive oxygen species such as superoxide, hydrogen peroxide, the hydroxyl radical These damage proteins, lipids and DNA [Federal Register, 1976]

Acute symptoms of copper poisoning by ingestion include vomiting, hematemesis (vomiting of blood), hypotension (low blood pressure), melena (black

"tarry" feces), coma, jaundice (yellowish pigmentation of the skin), and gastrointestinal distress Individuals with glucose-6-phosphate deficiency may be at increased risk of hematologic effects of copper Hemolytic anemia resulting from the treatment of burns with copper compounds is infrequent

Chronic (long-term exposure) effects of copper exposure can damage the liver and kidneys Mammals have efficient mechanisms to regulate copper stores such that they are generally protected from excess dietary copper levels

The U.S Environmental Protection Agency's Maximum Contaminate Level (MCL)

in drinking water is 1.3 milligrams per Liter The MCL for copper is based on the expectation that a lifetime of consuming copper in water at this level is without adverse effect (gastrointestinal effect) The U.S EPA lists evidence that copper causes testicular cancer as "most adequate" according to the latest research at Sanford-Burnham Medical Research Institute The Occupational Safety and Health Administration (OSHA) has set a limit of 0.1 mg/m3 for copper fumes (vapor generated from heating copper) and 1 mg/m3 for copper dusts (fine metallic copper particles) and mists (aerosol of soluble copper) in workroom air during an 8-hour work shift, 40-hour workweek [Curtis D Klassen, Ph.D., McGraw-Hill]

1.3.3 Lead Pb

Lead is a poisonous metal that can damage nervous connections (especially in young children) and cause blood and brain disorders Lead poisoning typically results from ingestion of food or water contaminated with lead; but may also occur after accidental ingestion of contaminated soil, dust, or lead based paint Long-term exposure to lead or its salts (especially soluble salts or the strong oxidant PbO2) can cause nephropathy, and colic-like abdominal pains The effects of lead are the same whether it enters the body through breathing or swallowing Lead can affect almost every organ and system in the body The main target for lead toxicity is the nervous system, both in adults and children Long-term exposure of adults can result in decreased performance in some tests that measure functions of the nervous system It may also cause weakness in fingers, wrists, or ankles Lead exposure also causes small increases in blood pressure, particularly in middle-aged and older people and can cause anemia Exposure to high lead levels can severely damage the brain and

kidneys in adults or children and ultimately cause death In pregnant women, high levels of exposure to lead may cause miscarriage Chronic, high-level exposure has shown to reduce fertility in males The antidote/treatment for lead poisoning consists

of dimercaprol and succimer

The concern about lead's role in cognitive deficits in children has brought about widespread reduction in its use (lead exposure has been linked to learning disabilities) Most cases of adult elevated blood lead levels are workplace-related High blood levels are associated with delayed puberty in girls Lead has been shown many times to permanently reduce the cognitive capacity of children at extremely low levels of exposure

During the 20th century, the use of lead in paint pigments was sharply reduced because of the danger of lead poisoning, especially to children By the mid-1980s, a significant shift in lead end-use patterns had taken place Much of this shift was a result of the U.S lead consumers' compliance with environmental regulations that significantly reduced or eliminated the use of lead in non-battery products, including gasoline, paints, solders, and water systems Lead use is being further curtailed by the European Union's RoHS directive Lead may still be found in harmful quantities in stoneware, vinyl (such as that used for tubing and the insulation

of electrical cords), and brass manufactured in China Between 2006 and 2007 many children's toys made in China were recalled, primarily due to lead in paint used to color the product [Stellman, Jeanne Mager (1998).]

Older houses may still contain substantial amounts of lead paint White lead paint has been withdrawn from sale in industrialized countries, but the yellow lead chromate is still in use; for example, Holland Colours Holcolan Yellow Old paint should not be stripped by sanding, as this produces inhalable dust

Lead salts used in pottery glazes have on occasion caused poisoning, when acidic drinks, such as fruit juices, have leached lead ions out of the glaze It has been suggested that what was known as "Devon colic" arose from the use of lead-lined presses to extract apple juice in the manufacture of cider Lead is considered to be particularly harmful for women's ability to reproduce Lead (II) acetate (also known

as sugar of lead) was used by the Roman Empire as a sweetener for wine, and some

consider this to be the cause of the dementia that affected many of the Roman Emperors

Lead as a soil contaminant is a widespread issue, since lead is present in natural deposits and may also enter soil through (leaded) gasoline leaks from underground storage tanks or through a waste stream of lead paint or lead grindings from certain industrial operations

Lead can also be found listed as a criteria pollutant in the United States Clean Air Act section 108 Lead that is emitted into the atmosphere can be inhaled, or it can

be ingested after it settles out of the air It is rapidly absorbed into the bloodstream and is believed to have adverse effects on the central nervous system, the cardiovascular system, kidneys, and the immune system [Hong, Youlian and Bartlett, Roger, ed (2008)]

In the human body, lead inhibits porphobilinogen synthase and ferrochelatase, preventing both porphobilinogen formation and the incorporation of iron into protoporphyrin IX, the final step in hemi synthesis This causes ineffective hemi synthesis and subsequent microcytic anemia At lower levels, it acts as a calcium analog, interfering with ion channels during nerve conduction This is one of the mechanisms by which it interferes with cognition Acute lead poisoning is treated using disodium calcium edentate: the calcium chelae of the disodium salt of ethylene-diamine-tetracetic acid (EDTA) This chelating agent has a greater affinity for lead than for calcium and so the lead chelae is formed by exchange This is then excreted in the urine leaving behind harmless calcium

1.3.4 Zinc Zn

Although zinc is an essential requirement for good health, excess zinc can be harmful Excessive absorption of zinc suppresses copper and iron absorption The free zinc ion in solution is highly toxic to plants, invertebrates, and even vertebrate fish The Free Ion Activity Model is well-established in the literature, and shows that just micro molar amounts of the free ion kills some organisms A recent example

showed 6 micro molar killing 93% of all Daphnia in water [Barceloux, Donald G.;

(1999)]

The free zinc ion is a powerful Lewis acid up to the point of being corrosive Stomach acid contains hydrochloric acid, in which metallic zinc dissolves readily to give corrosive zinc chloride Swallowing a post-1982 American one cent piece (97.5% of zinc) can cause damage to the stomach lining due to the high solubility of the zinc ion in the acidic stomach

There is evidence of induced copper deficiency at low intakes of 100–300 mg Zn/day; a recent trial had higher hospitalizations for urinary complications compared

to placebo among elderly men taking 80 mg/day [Fosmire GJ (1990)] The USDA RDA is 11 and 8 mg Zn/day for men and women, respectively Even lower levels, closer to the RDA, may interfere with the utilization of copper and iron or adversely affect cholesterol Levels of zinc in excess of 500 ppm in soil interfere with the ability of plants to absorb other essential metals, such as iron and manganese There

is also a condition called the zinc shakes or "zinc chills" that can be induced by the inhalation of freshly formed zinc oxide formed during the welding of galvanized materials

The U.S Food and Drug Administration (FDA) has stated that zinc damages nerve receptors in the nose, which can cause anomies Reports of anomies were also observed in the 1930s when zinc preparations were used in a failed attempt to prevent polio infections On June 16, 2009, the FDA said that consumers should stop using zinc-based intranasal cold products and ordered their removal from store shelves The FDA said the loss of smell can be life-threatening because people with impaired smell cannot detect leaking gas or smoke and cannot tell if food has spoiled before they eat it Recent research suggests that the topical antimicrobial zinc pyrithione is a potent heat shock response inducer that may impair genomic integrity with induction of PARP-dependent energy crisis in cultured human keratinocytes and melanocytes

In 1982, the United States Mint began minting pennies coated in copper but made primarily of zinc With the new zinc pennies, there is the potential for zinc toxic sis, which can be fatal One reported case of chronic ingestion of 425 pennies (over 1 kg of zinc) resulted in death due to gastrointestinal bacterial and fungal sepsis, while another patient, who ingested 12 grams of zinc, only showed lethargy and ataxia (gross lack of coordination of muscle movements) Several other cases have been reported of humans suffering zinc intoxication by the ingestion of zinc coins

Pennies and other small coins are sometimes ingested by dogs, resulting in the need for medical treatment to remove the foreign body The zinc content of some coins can cause zinc toxicity, which is commonly fatal in dogs, where it causes a severe hemolytic anemia, and also liver or kidney damage; vomiting and diarrhea are

possible symptoms Zinc is highly toxic in parrots and poisoning can often be fatal The consumption of fruit juices stored in galvanized cans has resulted in mass parrot poisonings with zinc

1.4 Analytical methods for determination of heavy metals in water and sediment samples

1.4.1 Electrochemical methods

1.4.1.1 Polarography

Polarography is a subclass of voltammetry where the working electrode is

a dropping mercury electrode (DME) or a static mercury drop electrode (SMDE) useful for its wide cathodic range and renewable surface It was invented by Jaroslav Heyrovský, who was for this invention awarded by Nobel’s prize in 1959

Polarography is an voltammetric measurement whose response is determined

by combined diffusion/convection mass transport Polarography is a specific type of measurement that falls into the general category of linear-sweep voltammetry where the electrode potential is altered in a linear fashion from the initial potential to the final potential As a linear sweep method controlled by convection/diffusion mass transport, the current vs potential response of a polarographic experiment has the typical sigmoidal shape What makes polarography different from other linear sweep voltammetry measurements is that polarography makes use of the dropping mercury electrode (DME) or the static mercury dropping electrode

A plot of the current vs potential in a polarography experiment shows the current oscillations corresponding to the drops of Hg falling from the capillary If one connected the maximum current of each drop, a sigmoidal shape would result The limiting current (the plateau on the sigmoid), called the diffusion current because diffusion is the principal contribution to the flux of electro active material at this point of the Hg drop life

The method has been used for the determination of heavy metals In Vietnam,

Tu Van Mac and Tran Thi Sau has studied about determination of copper, lead and cadmium in beer in Hanoi by alternating current differential pulse polarography with sensitivity accounting for 1ppb [Tu Van Mac, Tran Thi Sau]

Thanh Thuc Trinh, Nguyen Xuan Lang and their colleagues has applied polarimetry on determination of Zinc, Cadmium, Lead and Copper in some kinds of

food and agricultural soil It is experimented in environment of acetate buffer with system of 3 polars: hanging mercury drop electrode, reference electrode Ag/AgCl, auxiliary electrode Pt and electrodeionization potential accounting for -1.05V in 60 seconds [Thanh Thuc trinh, Nguyen Xuan Lang]

= f(E) are called voltammograms The potential is varied arbitrarily either step by step or continuously and the actual current value is measured as the dependent variable The opposite, i.e., amperometry, is also possible but not common The shape of the curves depends on the speed of potential variation (nature of driving force) and on whether the solution is stirred or quiescent (mass transfer) Most experiments control the potential (volts) of an electrode in contact with the analyte while measuring the resulting current (amperes) [Zoski, Cynthia G (2007-02-07)] Professor Petrovic and his colleagues used Differential pulse stripping voltametry to determine Cd and Pb in water after separating them from humic acid

by thin layer chromatographic method [Petrovic and Dewal, 1998]

Selehattin Yilmaz, Sultan Yagmur, Gulsen Saglikoglu, Murat Sadikoglu studied about direct determination of zinc heavy metal in the tap water carried out by differential pulse anodic stripping voltammetry technique at the glassy carbon electrode (GCE) The zinc ions were deposited by reduction at -1.5 V on a bare glassy carbon surface Then, the deposited metal was oxidized by scanning the potential of the electrode surface from -1.5 to -0.8 volt using a differential puls mode The stripping current arising from the oxidation of metal was connected with the concentration the metal in the sample The concentration of zinc heavy metal found

in tap water sample was determined to be 180 mg L-1 using 0.2 mol L-1 acetate buffer (pH: 3.50) [Selehattin Yilmaz, 2009]

1.4.2 Spectrophotometric methods

1.4.2.1 Ultraviolet-visible spectrophotometer

Ultraviolet-visible spectroscopy or ultraviolet-visible spectrophotometer Vis or UV/Vis) refers to absorption spectroscopy or reflectance spectroscopy in the ultraviolet-visible spectral region This means it uses light in the visible and adjacent (near-UV and near-infrared (NIR)) ranges The absorption or reflectance in the visible range directly affects the perceived color of the chemicals involved In this region of the electromagnetic spectrum, molecules undergo electronic transitions [ Prabhakar, Dubinskii, Editors and Dekker (2002)] This technique is complementary to fluorescence spectroscopy, in that fluorescence deals with transitions from the excited state to the ground state, while absorption measures transitions from the ground state to the excited state UV/Vis spectroscopy is routinely used in analytical chemistry for the quantitative determination of different analytes, such as transition metal ions, highly conjugated organic compounds, and biological macromolecules Determination is usually carried out in solutions

(UV-Gao Hong – Wen (China) used dithizone combining with Cd separation cells filter to determination of Cd (II) in sea water by UV/Vis spectroscopy with LOD is 0.006 ppm [Gao Hong – Wen (1995),]

A.M Garcia Rodriguez, A Garcia de Torres and J.M Cano Pavon studied about simultaneous determination of iron, cobalt, nickel and copper by UV-visible spectrophotometry with multivariate calibration Linear determination ranges of Co,

Ni, Fe and Cu are 0.2–1.3 mg/ml, 0.1–1.2 mg/ml, 0.1–1.1 mg/ml and 0.2–1.2 mg/ml respectively.A method for the simultaneous spectrophotometric determination of the divalent ions of iron, cobalt, nickel and copper based on the formation of their complexes with 1,5-bis(di-2-pyridylmethylene) thiocarbonohydrazide (DPTH) is proposed.[A.M Garcia, A Garcia and J.M Cano (1998)]

1.4.2.2 Atomic emission spectroscopy (AES)

Atomic emission spectroscopy (AES) is a method of chemical analysis that uses the intensity of light emitted from a flame, plasma, arc, or spark at a particular wavelength to determine the quantity of an element in a sample The wavelength of the atomic spectral line gives the identity of the element while the intensity of the emitted light is proportional to the number of atoms of the element A sample of a

material (analyte) is brought into the flame as a gas or sprayed solution [Stefánsson

A, Gunnarsson I, Giroud N (2007)] The heat from the flame evaporates the solvent and breaks chemical bonds to create free atoms The thermal energy also excites the atoms into excited electronic states that subsequently emit light when they return to the ground electronic state Each element emits light at a characteristic wavelength, which is dispersed by a grating or prism and detected in the spectrometer A frequent application of the emission measurement with the flame is the regulation of alkali metals for pharmaceutical analytics

Krzysztof Jankowski, Jun Yao, Krzysztof Kasiura, Adrianna Jackowska,

Anna Sieradzka studied about multielement determination of heavy metals in

water samples by continuous powder introduction microwave-induced plasma atomic mission spectrometry after preconcentration on activated carbon The experimental setup consisted of integrated rectangular cavity TE and vertically positioned plasma torch The satisfactory signal stability required for sequential analysis was attained owing to the vertical plasma configuration, as well as the plasma gas flow rate

compatibility with sample introduction flow rate The elements of interest (Cd, Cu,

Cr, Fe, Mn, Pb, Zn) were preconcentrated in a batch procedure at pH 8–8.5 after addition of activated carbon and then, after filtering and drying of the activated

carbon suspension, introduced to the MIP by the CPI system [Krzysztof Jankowski, Jun Yao, Krzysztof Kasiura, Adrianna Jackowska, Anna Sieradzka (2004)]

1.4.2.3 Atomic absorption spectroscopy (AAS)

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 AAS can be used to determine over

70 different elements in solution or directly in solid samples The technique makes use of absorption spectrometry to assess the concentration of an analyte in a sample

It requires standards with known analyte content to establish the relation between the measured absorbance and the analyte concentration and relies therefore on Beer-Lambert Law In short, the electrons of the atoms in the atomizer can be promoted to higher orbitals (excited state) for a short period of time (nanoseconds) by absorbing a defined quantity of energy (radiation of a given wavelength) [B.V L’vov (2005)] This amount of energy, i.e., wavelength, is specific to a particular electron transition

in a particular element In general, each wavelength corresponds to only one element, and the width of an absorption line is only of the order of a few picometers (pm), which gives the technique its elemental selectivity The radiation flux without a sample and with a sample in the atomizer is measured using a detector, and the ratio between the two values (the absorbance) is converted to analyte concentration or mass using Beer-Lambert Law

Hüseyin Bağ, A.Rehber Türker, Ramazan Coşkun, Mehmet Saçak, Mustafa Yiğitoğlu studied about determination of zinc, cadmium, cobalt and nikel by flame atomic absorption spectrometry after preconcentration by poly(ethylene

terephthalate) fibers grafted with methacrylic acid The batch adsorption method was

used for the preconcentration studies Effect of pH, amount of adsorbent, concentration and volume of elution solution, shaking time and interfering ions on the recovery of the analytes have been investigated Recoveries of Zn, Cd, Co and Ni were 97.3±0.4%, 98.3±0.2%, 94.1±0.3% and 96.5±0.6% at 95% confidence level, respectively, at optimum conditions Langmuir adsorption isotherm curves were also studied for the analytes The adsorption capacity of the adsorbent was found as 298,

412, 325 and 456 mg/g for Zn, Cd, Co and Ni, respectively [Hüseyin Bağ, 2000]

Nakashima and his colleagues in Okayama University (Japan) studied about determination of Cadmium in water by using AAS after separating Cd out of samples

by zirconi oxide [M.C Yebra , N Carro, A Moreno-Cid (2002)]

In addition, M.C Yebra , N Carro, A Moreno-Cid studied about

determination of copper in sea water by flow-injection- atomic absorption spectrometry By using the optimized flow systems, seawater samples were collected

and pre-concentrated in situ by passing them with a peristaltic pump through a column packed with Amberlite XAD-4 impregnated with the complexing agent 4-(2-pyridylazo) resorcinol Thus, copper is pre-concentrated without the interference of the saline matrix Once in the laboratory, the mini-columns loaded with copper are incorporated into a flow injection system and eluted with a small volume of a 40% (v/v) ethanolic solution of 3 mol l−1 hydrochloric acid into the nebulizer-burner system of a flame atomic absorption spectrometer Analysis of certified reference materials (SLEW-3 and NASS-5) showed good agreement with the certified value [Susumu, Masakazu (1983)]

Conclusion: Because the objects of our research are surface water and sediment samples containing heavy metals as Cd, Cu, Pb, Zn… the amount of heavy metals must be determined exactly in order to evaluate the quality of water Modern analytical methods such as GF-AAS, ICP-MS… require expensive equipments and costly fees In this case, using F-AAS is a reasonable choice with high sensitivity and the capability to analyze many elements in complex matrices, providing a good accuracy and precision result, short time for analyzing and cheap price The referenced results obtained by ICP-MS will be also included to recognize the ultra trace of heavy metal contents in some environmental samples

CHAPTER 2: EXPERIMENTS

2.1 Research Objects and research contents

2.1.1 Research objects

At present, the environmental impact is still poorly understood in Lao PDR It is lack

of information for herbicide and pesticide management The may be some problems have occurred as:

- People are unaware of dangers of heavy metals content in water and sediment

- High residue levels in water and sediment

- Threat to farmers’ health and aquatic ecosystems due to misuse and

misunderstand

- Using polluted surface water for agricultural purpose leads to accumulate heavy metals

This research aims to get quantitative determination of four main heavy metals (such

as Pb, Cd, Zn, Cu) in water and sediment samples in the ThadLuang Marsh and assessments the distribution these heavy metals contents in environmental samples of studied mash No sooner do many factories appear and develop increasing fast than water is polluted by heavy metals is over allowable limit Owing to not taking part in biochemical process, heavy metals such as Cd, Pb, Zn, Cu… are accumulated in human body, which leads to harmfulness for organism The fact that water is polluted

by heavy metal is often seen in rivers near industrial area, big cities and minerals exploiting area The main reason leading to heavy metals pollution is pouring into water environment a large amount of industrial and untreated wastewater Pollution

by heavy metals accumulated through foods directly into organism has negative effects on life environment In order to reduce consequence of this problem, it is necessary to cultivate measures of water treatment

2.1.2 Research contents

In order to gain a completely process, it is necessary to study systematically the following issues:

- Investigation of optimal conditions for determination of Pb, Cd, Zn, and Cu

in water and sediment using F-AAS

- Investigation of sample matrix’s effects

- Investigation of other interferences to analytical results

- Determination of Cd, Cu, Pb, Zn content in water and sediment samples

collected in ThadLuang marsh in May, 2011

2.2 Chemicals and Apparatus

2.2.1 Chemicals

All reagents were of Merck analytical grade or ultra-pure grade for ICP-MS

measurement Working solutions of analysed ions were prepared by dilution of

standard solutions of 1000 ppm standard solutions of Zn 2+, Cu2 +, Pb+2, Cd2 +

- 2% solutions of HNO3, HCl, CH3COONH4 were prepared from 65% solution

of HNO3 , 36% solution of HCl and 99% solution of CH3COONH4,

respectively

- 10% solution of HCl, HNO3 was prepared from con.HNO3 68%

- Super pure water (Resistance >=18.2 MΩ) and Argon, super pure grade

(>=99.999) for ICP-MS measurement

All standard reagent solutions were stored in low density polyethylene bottles

2.2.2 Apparatus

- Beaker25, 50, 100ml capacity

- Pipettes 1, 2, 5, 10, 25 ml capicity

- Pipetteman 20, 100, 200, 1000, 5000 μl capicity

- Hopper glass, filter paper, pH indicator

- Elementary flasks 50, 100, 250 ml capacity

- Glass volumetric flasks: 25, 50, 100 and 25 ml capacity

All laboratory glassware and plastic ware, polyethylene sample and reagent bottles

were cleaned by soaking in a detergent solution, rinsed with ultra pure water from a

Millipore Q50 system and soaking in a HNO3 ( 2%), v/v) bath overnight This was

followed by thorough rinsing with pure and dried before use

- Calculations: MINITB release 14 for window

2.2.3 Equipments

- AAS- novAA spectrometer with pneumatic nebulisation and mono- element lamps with hollow cathode made by Analytikjena (Fig 3)

Figure 2.1: Spectrometer atomic absorption novAA 6800, Shimazhu

2.3 Sampling and Sample Preparation

2.3.1 Study Area

2.3.1.1 Water samples

Eight sampling points were located within marsh were shown in Figure 2.2 The description of the characteristics of water sampling points is given in table 2.1

Table 2.1: Characteristics of the water sampling points in Thadluang marsh

Figure 2.2: The map of Thadluang marsh showing water sampling sites

Figure 2.3: The map of Thadluang marsh showing sediment sampling sites