International Summer Water Resources Research School Dept. of Water Resources Engineering, Lund University

Transcription

1 International Summer Water Resources Research School Dept. of Water Resources Engineering, Lund University Determination of Arsenic in water and sediment samples in Jiulongjiang estuary By Anna Pärsdotter 2012

2 Abstract Arsenic occurs naturally in sulfide minerals, as for example in pyrite. However, human activities such as manufacture of pesticides, mining, combustion of fossil fuels, and preservative of timber also contribute to its occurring in environment. Drinking water containing high levels of arsenic can cause human health problems such as neurological diseases, cancers etc. This has been reported from countries such as China, USA, Chile and Bangladesh, and can be today considered as a worldwide problem. The aim of this project is to analyze arsenic in water and sediment samples to observe the distribution of arsenic in the study area; Jiulongjiang estuary near Xiamen. Various water and sediment samples were collected and analyzed with Hydride Generation- Atomic Fluorescence Spectrometry method (HG-AFS). The analytical results of the water and sediment samples show that the arsenic distribution in the estuary is normal, the area is not polluted. The water sample does not exceed WHO s limitation for drinking water. All the samples, both sediment and water, are also placed in the best level in Quality Standards of Marine Sediment/Water in China. The concentration of arsenic in the water samples was too low to perform the speciation with Ion exchange liquid Chromatography- HG-AFS method (IC-HG- AFS) thus the different arsenic species was unidentified. The speciation analysis of sediment samples was though carried out with IC-HG-AFS and two inorganic species, As(III) and As(V), were detected. Keywords: arsenic, estuary, water samples, sediment samples, HG-AFS, speciation 1

3 Table of Contents 1. Introduction Background Limitations Aim and scope Toxicity of Arsenic Analyzing methods Theory Ion exchange liquid Chromatography and Hydride Generation Atomic Fluorescence Spectroscopy (IC-HG-AFS) Methodology for experiment Sampling and sampling site Procedure Materials and reagents Cleaning Instrumentation Water sample preparation Sediment sample preparation Sediment sample preparation for speciation Calibration curves Result and discussion Water sample Sediment sample Sediment and Water samples Speciation analysis of sediment samples...16 Measured value (mg/kg)

4 4.5 Sources of error Conclusion Acknowledgement Bibliography Appendix

5 1. Introduction 1.1 Background Arsenic is a semimetal and the twentieth most abundant element in Earth's crust, with a presence close to 2 mg / kg (Mohana & Pittman, 2007). Arsenic occurs naturally in sulfide minerals, as for example in pyrite. However, human activities such as manufacture of pesticides, mining, combustion of fossil fuels and preservative of timber also contribute to its occurring in environment (Duker, Carranza, & Hale, 2005). People are exposed for inorganic arsenic via drinking water, air, soil, and organic arsenic mainly through fish and shellfish. Drinking water containing high levels of arsenic can cause human health problems such as neurological diseases, cancers etc. This has been reported from countries such as China, USA, Chile and Bangladesh, and can be today considered as a worldwide problem (Mohana & Pittman, 2007). Compounds of organic arsenic can be found in food, but their rapid passage through the body makes them relatively harmless. Inorganic arsenic accumulates in the body and concentrated with time and can thus cause damage over time (Health and Human Services Department, 2006). 1.2 Limitations The time period for the study had a limitation of four weeks. The sampling was carried out once during these weeks. For a more complete distribution of arsenic in the area more sampling occasions are needed. Due to the time limitation there has been difficult to understand the equipment completely. The author has never worked with IC-HG-AFS method before and is therefore not as skilled as the other members of the lab group. 1.3 Aim and scope The aim of this project is to analyze arsenic in water and soil samples to observe the distribution of arsenic in the studied area. The studied area is the Jiulongjiang estuary near Xiamen. Various water and soil sediment samples will be collected and the samples will be analyzed with Hydride Generation- Atomic Fluorescence Spectrometry (HG-AFS). If the concentration is high enough, speciation of the samples will be done, using separation of Ion exchange liquid Chromatography and Hydride Generation- Atomic Fluorescence Spectrometry (IC-HG-AFS). The analytical results will be summarized and compared, thus the distributions of arsenic in the study areas will be pictured. 1.4 Toxicity of Arsenic Limitation for arsenic in drinking water is 0.01 mg /L which is based on cancer risk. WHO recommended value for the maximum tolerable weekly intake of inorganic arsenic is set at 15 micrograms/kg body weight, which translated into daily intake is about 150 mcg/day for an adult (Mohana & Pittman, 2007). Unpolluted seawater usually contains a total concentration that varies from 1 to 3 mg/l. The seawater can have higher values, depending on the geochemical and anthropogenic activity associated the specified region (Correia, Gonçalves, Azevedo, Vieira, & Campos, 2009). Toxicity of arsenic differs a great deal with its forms. Compounds such as arsenite (As(III)) and arsenate (As(V)) are extremely toxic, both are inorganic. The organic compounds, such as monomethylarsonic (MMA) and dimethylarsinic acid (DMA), are less toxic (Wei & Liu, 2007). Arsenic is considered to be about four times as toxic as mercury, and As (III) is about 60 times 4

6 more toxic than the As(V). It is possible to remove the As(V) with an existing water treatment, but difficult to remove the As(III) (Health and Human Services Department, 2006). 1.5 Analyzing methods When analyzing the species of arsenic, one analyzes the different organic or inorganic arsenic compounds, not the total arsenic amount in a sample. This is usually performed by using a separation procedure before the sample is placed in a detection system. Most commonly, different types of chromatography or chelation-extraction techniques are employed in combination with atomic absorption spectrometry (AAS), inductively coupled plasma atomic emission spectrometry (ICP-AES), or inductively coupled plasma mass spectrometry (ICP-MS) detection methods. For chromatographic separation, the most generally used methods are cation exchange, anion exchange and reversed-phase chromatography or a combination of these methods (Wei & Liu, 2007). There are different methods of analysis to determine the concentration of arsenic, for example AAS, which is useful for arsenic in biological material, ICP-AES that are used for analysis of arsenic with higher concentrations, and at low levels ICP-MS is the better choice (EPA, 1999). However, it is complicated for analytical instrument to distinguish As(III) and As(V). It is also complicated to separate analytically organic and inorganic arsenic. When performing an AAS analysis, the sample solution is heated in a flame or in a graphite furnace and this is done until the element atomizes. The atomic vapor, in its ground state, absorbs monochromatic radiation from a source and after this a photoelectric detector measures the intensity of transmitted radiation. The samples are prepared by digestion with nitric, sulfuric, and/or perchloric acids (Arsenic, analytical methods). ICP-MS is a fast and high sensitive measure. On the other hand, the cost of ICP-MS instruments and their maintenance are expensive which limits the applications for everyday analysis (Wei & Liu, 2007). 2. Theory 2.1 Ion exchange liquid Chromatography and Hydride Generation Atomic Fluorescence Spectroscopy (IC-HG-AFS) Arsenic occurs in different forms, for example as arsenite (As(III)), arsenate (As(V)) monomethylarsonic (MMA) and dimethylarsinic acid (DMA). Since the different forms wary in toxicity it is important to both confirm the total amount of arsenic and distinguish different forms. To be able to distinguish different forms chromatography separation coupled to atomic spectrometry is often used (Wei & Liu, 2007). Atomic spectrometric methods like AAS, AFS, ICP OES and ICP-MS, are the most popular for the determination of arsenic in a sample. They all often use HG technique in a combination. In the AFS method, the usage of HG is unavoidably, this because the full detection potential from AFS will only be reached in connection to HG (Correia, Gonçalves, Azevedo, Vieira, & Campos, 2009). The recent decades a new method has been developed, that is, HG combined with atomic fluorescence spectroscopy (HG-AFS) to determine the total quantity of arsenic in a 5

7 sample. This method has sensitivity better than 20 parts per trillion (Arsenic, analytical methods). In AFS one analyzes the fluorescence from molecules in a solution. The molecules, which one wants to analyze, emit light spontaneously when, for example, UV light induce the electrons to excites and causes them to emit light. The emitted light intensity and amplitude are studied by a spectrometer which identifies the atoms in the solution (Hof, Fidler, & Hutterer, 2005). Obtaining the instrument and its maintenance for HG-AFS method is cheaper compared to ICP-MS (Wei & Liu, 2007). In chromatography, separation of ions takes place based on their charge. Ion chromatography (IC) consists of an ion-exchange column. In IC, either anion or cation exchange columns can be used, but today, columns of mixed both anion and cation exchangers are accessible. Mixed columns have better separation efficiency (Ali & Jain, 2004). In HG-AFS detection tetrahydroborate is used to change the hydride forming elements into hydride. The hydride is separated from the reaction mixture; this is done by with a gas liquid separator (GLS), and after this the hydride together with a carrier gas is directed into an atomizer. The GLS, in HG system, influences the separation of the hydride gas, background noise and the interference (Wei & Liu, 2007). The capability of removing moist from the gas-liquid separation system is important, this because during gas liquid separation, moisture can cause problems such as the loss of sensitivity or a blockage of the transfer line (Wei & Liu, 2007). 3. Methodology for experiment 3.1 Sampling and sampling site The sampling site, Jiulongjiang estuary, is located near Xiamen city in Fujian Province. Figure 1. Location of the sampling point, Jiulongjiang estuary and Xiamen. Firstly various water and sediment samples were collected. In total there were 14 water samples collected at high tide (more sea water) and low tide (more river water), whereof 2 6

8 samples were in parallel which led to 12 different sample points. There were in total 6 sediment sampling points from the estuary area. The samples include: waste seawater samples soil samples from a coal-fired power plant equipped with a seawater flue gas desulfurization system seawater samples from two waste discharging outlets seawater and sediment samples from Xiamen western harbor areas. Figure 2. The sampling points in Jiulongjiang estuary near Xiamen. The longitude and latitude coordinates for the sampling points are attached in appendix. A coal fired power plants is situated near sapling points: 7, 8, 9 and 13. Sampling point 13 is used only for sediment, that s why it got the last number. The sampling point 1 is far away from the power plant. 3.2 Procedure In the experiment hydrochloric acid (HCl) together with potassium borohydride (KBH 4 ) and Thiourea reduces As(IV) to As(III) and then As(III) to Arsine (AsH 3 ) during the hydride generation. HCl and KBH 4 react and produce hydrogen gas. As (III) is reduced to Arsine gas by reacting with the hydrogen gas. After the preparation steps, the measuring solutions were submitted to the instrumental analysis, which can be seen in Figure 3. Arsine and together with the carrier gas, Argon, then flows through two gas-liquid separators (GLS). In the flame atomizer, the hydrogen gas burn together with argon gas and the molecules are dissociated into free atoms, its elemental form. By driving this gas and argon through the flame, the AFS can determine the fluorescence intensity of the arsenic in the sample. 7

9 Figure 3. Flow-chart for the AFS. The reaction process of the experiment is shown below in Figure 4. Figure 4. Reaction process for arsenic. To determine the different species, the samples were analyzed in an ion chromatography instrument, where separation of ions takes place based on their charge. Then AFS determine the concentration of different species by analyzing their specific light intensity. 3.3 Materials and reagents Reagents used in the experiment are shown in table 1 below. Table 1. Reagents used. Reagent Chemical formula Concentration/Purity Thiourea SC(NH 2 ) 2 99 % L-Ascorbic acid C 6 H 8 O 6 99,7 % Potassium Hydroxide KOH 85 % Potassium Borohydride KBH 4 95 % 8

10 Hydrochloric acid HCl % Nitric acid HNO 3 65 % Diammonium hydrogen (NH 4 ) 2 HPO 4 99 % phosphate Phosphoric acid H 3 PO 4 85 % Formic acid HCOOH 10 % 3.4 Cleaning All beakers and colorimeter tubes were cleaned before using them for the samples. Before the sample preparation the tubes were washed three times with deionized water. After using the tubes they were also washed three times in tap water and then three times in deionized water. During the night the tubes were stored in a plastic box containing HCl acid. 3.5 Instrumentation In the table 2 below a list of equipments and instruments used in this experiment is shown. Table 2. Instruments used. Instrument Model Parameters Atomic Fluorescence Spectroscopy AFS-820 Negative high voltage of multiplier: -280 V Hollow cathode lamp current: 60 ma Speed of peristaltic pump: 25 rpm Partial pressure of argon: 0.2 MPa Flow rate of carrier gas: 150 ml/min Flow rate of shield gas: 1000 ml/min Frozen-dry Labconco Freezone 4,5/Freeze Dry System Heater HH1 Ion-Chromatography Hamilton PRP-X100 Anion exchange column Guard column: PRP-X100 Mobile Phase: 12 mmol/l (NH 4 ) 2 HPO 4 Injection volume: 100 μl Flow rate: 1.25 ml/min Ultra sonic extraction KQ-300DA Centrifuge Anke TDL80-2B Rotation per minute:

11 3.6 Water sample preparation In the first reagent preparation, 25 g of Thiourea (SC(NH 2 ) 2 ) and 15 g of L-Ascorbic (C 6 H 8 O 6 ) acid were mixed with 500 ml of deionized water. In the second reagent, 20 g of potassium borohydride (KBH 4 ) were mixed with 2, 5 g potassium hydroxide (KOH) in 1 liter of deionized water. KOH is added because KBH 4 is unstable and KOH decompose KBH 4. Then the first regent, 5 ml, was added to a colorimeter tube together with 2.5 ml of HCl and 17.5 ml of the water sample. 3.7 Sediment sample preparation A regent was first prepared, which consisted of 25 ml nitric acid (HNO 3 ) and 75 ml of HCl, these were mixed together with 100 ml of deionized water. The sediments were frozen-dried before analysis. The sediment samples were placed in a freeze-dry instrument, in -40 and vacuum for2 days. After 2 days the samples were grinded (200 mesh) into smaller pieces in a moratorium, and filtered in a sieve. Then 0.2 gram of the filtered samples was placed in a tube together with 10 ml reagent. After this the tube was placed in a heater and boiled for one hour, during this hour the samples digested into a liquid which could be prepared in the same way as the water samples. 3.8 Sediment sample preparation for speciation The mobile phase reagent was first mixed, by adding 1, 5848 g of ammonium hydrogen phosphate ((NH4) 2 HPO 4 ) into 1 L of deionized water. To adjust the ph to 6 of the reagent, HCOOH was added. Ultra sonic extraction: A reagent for the extraction was mixed, 3.4 g of phosphoric acid (H 3 PO 4 ) added together with deionized water into a 100 ml tube. There after 4 ml of the reagent and 0.1 g of sediment were added into a tube. The tubes with sample and reagent were placed inside the ultra sonic instrument for 10 minutes and then centrifuged for 20 minutes. The liquid, not the sediment deposit, was placed in new tubes and then placed in the ultra sonic instrument for another 10 minutes and at last centrifuged for 20 minutes again. The ion chromatography separation requires no particles in sample solution, thus the samples were filtered through a membrane (0.22 μm) and into a new tube. The tubes were placed in the IC-HG-AFS instrument and 100 μl of the sample were injected. To control the data quality, three parallel samples at two sampling points, F and M, were analyzed. 3.9 Calibration curves In the experiment, a standard curve of arsenic was created using the standard solution 100 ng/ml. With the calibration curves the concentration of arsenic in the samples can be determined. Two curves were obtained for two types of sample analysis i.e. water samples and sediment samples. The concentrations used in the curve were 0 ng/ml, 0.5 ng/ml, 1 ng/ml, 2 ng/ml, 4 ng/ml and 10 ng/ml. The final total volume should be 25 ml and to get the wanted concentrations, 0, ml, 0.25 ml, 0.5 ml, 1 ml and 2.5 ml of standard arsenic (As(III)) solution was added to a colorimeter tube and then filled with ultra pure water until the total volume reached 25 ml. 10

12 Area Area Intensity (mv) Intensity Anna Pärsdotter y = 220,55x + 335,15 R² = 0, Concentration As(III) μg/l Figure 5. Calibration curve for water samples y = 213,65x + 326,26 R² = 0, Concentration As(III) μg/l Figure 6. Calibration curve for sediment samples. The R 2 value is in water curve and for the sediment curve; both were close to 1, which indicated that the result from the instrument was reliable. For the speciation of sediment, four calibration curves were made, one for each species investigated. The species investigates included arsenite (As(III)) and arsenate (As(V)), both are inorganic and organic compounds, such as monomethylarsonic (MMA) and dimethylarsinic acid (DMA). As(III) As (V) y = 58,6x + 56,41 R² = 0, y = 7,4997x - 4,7088 R² = 0, Concentration (μg/l) Concentration (μg/l) Figure 7. Calibration curves for As(III) and As(V). 11

13 Area Area Anna Pärsdotter DMA y = 24,834x + 62,418 R² = 0, Concentration (μg/l) MMA y = 17,965x + 54,227 R² = 0, Concentration (μg/l) Figure 8. Calibration curves for DMA and MMA. 3. Result and discussion 4.1 Water sample The concentration in the water samples are shown in table 3 below. These values are calculated from the calibration curve and the fluorescence value. During high tide, the samples contained mostly seawater and during low tide river water. Table 3. Concentration in water samples at low and high tide. Station Concentration, high tide, (μg/l) Concentration, low tide, (μg/l) Mean value, (μg/l) 1 1,583 1,459 1, ,333 1,205 1, ,473 1,324 1, ,385 1,301 1, ,267 1,464 1, ,485 1,589 1, ,587 1,481 1, ,529 1,174 1, ,414 1,232 1, ,4010 1,379 1, ,617 1,523 1, ,502 1,523 1,512 Mean: 1,465 1,388 The sampling points with the highest concentrations were 7 (1.587 μg/l), 11 (1.617 μg/l) and 1 (1.583 μg/l) during high tide. Low tide gave the highest values at 11 (1.523 μg/l) and 6 (

14 Concentration (μg/l) Anna Pärsdotter μg/l). The seawater in high tide had a mean concentration of 1.47 μg/l and low tide, 1.38 μg/l. Table 4. Four levels of the Quality Standards of Marine Water (Chinese Standard, 2007). Quality Standards of Marine Water in China (mg/l) Level I II III IV Concentration of arsenic China has four levels of marine water quality standards, showing in Table 4. All the samples from the estuary had concentration in the level one, i.e mg/l. The highest value at 11 has μg/l, is a great deal lower than the limit 20 μg/l. This indicates that the arsenic concentration is normal. The European guideline for arsenic in drinking water is in accordance with the WHO guideline of 10 μg/l (Halem, Bakker, Amy, & Dijk, 2009). All the samples from the estuary had a lower concentration than the limitation. This shows that no arsenic source pollution site is situated along the rivers catchment area or close to the estuary. Unpolluted seawater usually contains a total concentration that varies from 1 to 3 mg/l, which is the case for the samples here (Correia, Gonçalves, Azevedo, Vieira, & Campos, 2009) 1,8 1,6 1,4 1,2 1 0,8 0,6 0,4 0, Sampling point High tide Low tide Figure 9. Concentration of arsenic at low and high tide. After using statistics method of paired samples test, it was found that p-value was which was close to limit value of If the p-value is below 0.05, a significant difference between samples exists. Since p-value is above 0.05, the sets of data (high tide and low tide) had small differences, bit not significant. Sampling points 11, 7 and 1 had the highest value in Figure 9 above, and only 7 is situated close the coal fired power plant. Sampling point 1 is far away from the power plant, but still had a high value; this indicates that the plant does not affect the arsenic concentration. The concentration of arsenic in the water samples was too low to determine the species. 13

15 Concentration (μg/g) Anna Pärsdotter Sediment sample The concentration of arsenic in sediment is best shown in μg/g, so firstly a recalculation from μg/l was made from this equation: This equation is originates from the fact that 0.2 gram of sediment was put in a 25 ml tubes. Thereafter 2 ml of the mix was added in a 50 ml tube. The concentration of arsenic in sediment samples are shown in table 5 below. Table 5. Concentration of arsenic in sediment. At six of the sampling points sediment samples was taken. Station Concentration (μg/g) 1 11, , , , , ,65 The concentration was relatively evenly distributed among the sediment samples as can be seen in Table 5 and Figure 10. The highest value at C1 has μg/g and the lowest at C2 has μg/g Sampling point Figure 10. Concentration of arsenic in sediment. Table 6. Three levels of Quality Standards of Marine Sediment (Chinese Standard, 2007). Quality Standards of Marine Sediment in China (μg/g) Level I II III Concentration of arsenic The concentration in all the sediments samples are placed in level one of Quality Standards of 14

16 Marine Sediment in China. The highest value at 3, μg/g, is almost half of the limit for level one, 20 μg/g. Therefore, the sediment does not seem to be polluted by arsenic and the surrounding activity does not seem to contribute to contamination of the investigated area. Arsenic in soil, for areas that are planned for residential use, the standards and guidelines vary within the European countries; the concentration ranges from 2 in Norway to 110 μg/g in Belgium. If the areas will be utilized by industries, the standards are usually higher. For Sweden, the soil standard for industrial applications is 15 μg/g if the groundwater at the site will be used and 40 μg/g if it is not (Henke, 2009). 4.3 Sediment and Water samples To see the differences in concentration between sediment and water sample at the same sampling point, the values are shown in Figure 9 below. Figure 11. Concentration of arsenic in sediment and water samples at the same sampling point. Both for the sediment and the water samples, the result was relatively evenly distributed, but this applied for sediment more than water. The sediment samples had a bit higher concentration compared to the water samples. In sediment, arsenic was transported to estuary and accumulated there. Sampling point 1 had high value both for sediment and water, which is situated far from the coal fired power plant and more out in the sea. This indicates that the coal fired power plants does not affect the arsenic concentration in the estuary. The concentration in both water and sediment samples are normal and both are in the level one in Quality Standards of Marine Sediment in China, which shows that the water and sediment is clean and not polluted. Although the concentration of arsenic is normal in the sediment and water, human activities in the nearby surroundings can increase the arsenic concentration in the estuary. Arsenic can for example originate from land run off. Example of activities in the surrounding area that can 15

17 increase the concentration are; waste disposal, use of fertilizers, pesticides, herbicides in agriculture and industries. In 1979 in the U.S, the total amount of arsenic released into the environment as a result of anthropogenic activities 81% was deposited on land. (Duker, Carranza, & Hale, 2005) 4.4 Speciation analysis of sediment samples Speciation in water samples could not be done since the samples had very low concentration, but it was possible for the sediment samples. The resulting data from the IC-HG-AFS instrument were analyzed in software OriginPro 8 to get more understandable data. The software integrated the peaks of the fluorescence curves from the analysis, and the area for the species was gained. The result from the speciation is shown in Table 7 below. To get the concentration in μg/g the following calculations were made: Table 7. Species in sediment samples. Sample As(III) (μg/g) As(V) (μg/g) 1 1,568 12,33 3 1,734 11,39 9 1,342 12, ,575 14, ,345 13, ,710 10,99 As it can be seen in Table 7 and Figure 12, only two species existed in the sediment, i.e., As(III) and As(V). As(V) existed in higher concentration, but still below level one in Quality Standards of Marine Sediment in China. 16

18 Concentration (μg/g) Anna Pärsdotter Species in sediment sampling point As(III) As(V) Figure 12. Species in sediment at different sampling points. In sample from sampling points 1 and 13 a standard solution was added and the recoveries from the samples are shown in Table 8 below. Table 8. Recovery from sample point 1 and 13. Sample point 1 As(Ⅲ) DMA MMA As(V) Background level (mg/kg) 19,61 154,1 Spiked with (ng/ml) ,438 95, ,62 436,56 Measured value (mg/kg) Recovery (%) 63,67 95,01 120,6 141,2 Sample point 13 As(Ⅲ) DMA MMA As(V) Background level (mg/kg) 21, ,36 Spiked with (ng/ml) Measured value (mg/kg) 48,041 82, ,91 389,04 Recovery (%) 53,327 82, ,91 125,84 To be able to see if the speciation data were accurate and reliable, the parallelity and RSD (relative standard deviation) should be investigated. Most of the RSDs in this study were below 5 %, which means the data were trustworthy. Parallelity was calculated from two parallel samples taken; at sampling point 1 and 13 The parallelity for 1: and 13: 1.388, which also indicates accuracy. Detection limits for the species were also calculated: 17

19 Table 9. Detection limit. Detection Limit As(Ⅲ) DMA MMA As(V) 0,4750 1,121 1,550 3, Sources of error The main source of error is the sampling. During the sampling a lot of things could have affected the samples: pollution, movements of the boats, the water current affected the boat s position and thereby the location of each sampling point etc. Since we only took samples one time, this means the data are probably no representative enough to get a good distribution. Another factor contributing to errors can be the reagent used in HG-AFS; if they are not exactly mixed the reduction to Arsine is perhaps not complete. There can also be pollution in the AFS instrument and tubes which can affect the fluorescence. 5 Conclusion Analysis of the water and sediment samples shows that the arsenic distribution in the estuary was normal, i.e. the area is not polluted. The water sample did not exceed WHO s limitation for drinking water (10μg/L). All the samples, both sediment and water, are also placed in the best level in Quality Standards of Marine Sediment/Water in China. The mean value for the water samples at high tide was 1,465 μg/l and low rides μg/l. Even though there was a small difference between high and low tide, the statistics method of paired samples shows that there was no significant difference between the two sets of data. The sediment samples had a higher concentration compared to the water samples; the highest value was μg/g. The result show that the water and sediment is clean, and no arsenic pollution source exists in the surroundings. The concentration of arsenic in the water samples was too low to perform the IC- analyze, i.e., the different arsenic species was unidentified. The speciation analysis of sediment samples was though carried out with IC-instrument and two species was detected; arsenite As(III) and arsenate As(V), both inorganic. The dominant form of arsenic in sediment samples was arsenate As(V). The presence of As(V) was ten times higher compared to As (III). 6. Acknowledgement The author would like to thank Professor. Dongxing Yuan for valuable instruction about the project, and also information about China and its culture. The author would also like to thank research assistant Shanshan Lin for all the help during this four weeks and of course the undergraduate students Bingyan Lu and Zhaoying Chen. 7. Bibliography Ali, I., & Jain, C. K. (2004). ADVANCES IN ARSENIC SPECIATION TECHNIQUES. Intern. J. Environ. Anal. Chem, Vol. 84, No. 12, pp ,. 18

20 Arsenic, analytical methods. Retrived from Lab assitanct Chinese Standard, G. (2007). The speciation for marine montoring- Part 5: Sediment analysis. GB Correia, C. L., Gonçalves, R. A., Azevedo, M. S., Vieira, M. A., & Campos, R. C. (2009). Determination of total arsenic in seawater by hydride generation atomic fluorescence spectrometry. Microchemical Journal 96 (2010), Duker, A. A., Carranza, E., & Hale, M. (2005). Review article, Arsenic geochemistry and health. Enviroment International, EPA, U. S. (1999). Analytical Methods Support Document For Arsenic In Drinking Water. Washington. Halem, D. v., Bakker, S. A., Amy, G. L., & Dijk, J. C. (2009). Arsenic in drinking water: not just a problem for Bangladesh. Delft, The Netherlands: Copernicus Publications on behalf of the Delft University of Technology. Health and Human Services Department. (2006, october). Retrieved march 29, 2012, from Socialstyrelsen: Dricksvatten med avseende på arsenik: Henke, K. (2009). Arsenic: Environmental Chemistry, Health Threats and Waste Treatment. Online. Hof, M., Fidler, V., & Hutterer, R. (2005). Fluorescence Spectroscopy in Biology Advanced Methods and their Applications to Membranes, Proteins, DNA, and Cells. Germany: Springer Berlin Heidelber. Lenntech. (2011). Lenntech, Water treatment solutions.. Retrieved july 1, 2012, from Mohana, D., & Pittman, C. U. (2007). Arsenic removal from water/wastewater using adsorbents A critical review. Journal of Hazardous Materials, Wei, C., & Liu, J. (2007). A new hydride generation system applied in determination of arsenic species with ion chromatography hydride generation-atomic fluorescence spectrometry (IC HG-AFS). Talanta,

21 8. Appendix Table 10. Longitude and latitude for the sampling points. station longitude and latitude '19.06"N '9.57"E '43.94"N 118 0'3.85"E '16.56"N 118 0'4.02"E '23.25"N 118 0'41.34"E '40.80"N 118 0'55.44"E '2.12"N 118 1'54.26""E '26.46"N 118 1'57.90""E station longitude and latitude '27.60"N 118 2'7.32"E '21.54"N 118 1'58.62"E '41.78"N 118 2'41.03"E '17.42"N 118 3'5.10"E '44.07"N 118 3'15.08"E '26.7"N 118 2'3"E 20