The 3rd ISPRS Workshop on Dynamic and Multi-Dimensional GIS & the 10th Annual Conference of CPGIS on Geoinformatics

Chen, Jun

Bibliographic data

Monograph

Persistent identifier:: 856566209

Author:: Chen, Jun

Title:: The 3rd ISPRS Workshop on Dynamic and Multi-Dimensional GIS & the 10th Annual Conference of CPGIS on Geoinformatics

Sub title:: May 23 - 25, 2001, Bangkok, Thailand

Scope:: VI, 434 Seiten

Year of publication:: 2001

Place of publication:: Pathumthani, Thailand

Publisher of the original:: AIT

Identifier (digital):: 856566209

Illustration:: Illustrationen, Diagramme, Karten

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Monograph

Collection:: Earth sciences

Chapter

Title:: CIS AIDED CHARACTERIZATION OF SOIL AND GROUNDWATER ARSENIC CONTAMINATION IN SOUTHERN THAILAND. Jianjun ZHANG, Xiaoyong CHEN, Preeda PARKPIAN, Monthip Sriratana TABUCANON, Janewit WONGSANOON, Kensuke FUKUSHI, Skorn MONGKOLSUK and N.C.THANH

Document type:: Monograph

Structure type:: Chapter

ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS”, Bangkok, May 23-25, 2001 359 This suggests that the arsenic in shallow groundwater may come from the recharge of surface water due to precipitation. 3.2 ARSENIC LEVEL IN DEEP GROUNDWATER The deep groundwater is the water from the lower aquifer, normally from depth 15m to 50m in study area. The map of total arsenic level in deep groundwater was also interpolated. The area with arsenic level higher than 50 ppb is 7,057,125 m 2 that occupies 83.93% of the total interpolated. On the other hand, the area with arsenic level lower than 50 ppb is 1,351,475 m 2 , stands for 16.07%. This showed the contamination situation in deep groundwater was very severe. The mean value of total arsenic was 0.26 ppm, 5.2 times higher than limit. These maps also showed the highest arsenic zone with the highest value 4.01 ppm. (Fig. 3) The map in Fig. 3 shows the hot spots to be mostly in the vicinity of foot hill concentrator, where huge amount of mining waste were dumped along the river bank. The sample with the highest arsenic level is also observed at this site. The other sample sites with higher arsenic level were located among the center of study area, where waste dump sites are present. Comparing with the shallow groundwater arsenic level, this map shows a larger area with arsenic level higher than 50 ppb. In order to testify the relationship between the mining waste sites and arsenic level in deep groundwater, a correlation test shows a slightly correlative relationship between the distance to mining and waste sites and the arsenic level in deep groundwater (R=-0.661, P<0.05, Table 2). This result suggests that the pollution mechanism in varied aquifer may be different. 3.3 ARSENIC LEVEL IN SOIL The total arsenic concentration (soil elution) in surface soil (30cm underground) was displayed in Fig. 4. The area with elution arsenic level higher than 50 ppb was 2,694,675 m 2 , occupied 32.05%. While the area with elution arsenic level lower than 50ppb was 5,713,925 m 2 , the percentage is 67.95% in total area. The mean arsenic elution level was 87.83 ppb, with the highest value 1570ppb. Provided the surface soil in study area is 1-2 meters deep (average 1.5meter), the total contaminated soil would add up to 4,042,012.5 m 3 . Due to the lack of arsenic standard in soil, it was hard to say whether it was polluted or not, so, the elution arsenic level was only used as reference. Correlation test between surface soil elution arsenic level with distance to mining and waste site show a very strong significance within 300 meters range(R=-1,Table 3). However, from the source to 1,000 meters range, a less significance was observed(R=-0.636, P<0.05, Table 3). This strongly suggests that the mining and waste sites are the major pollution source for surface soil arsenic pollution. 3.4 ARSENISM PATIENTS’ DISTRIBUTION AND GEOLOGICAL FEATURES Arsenism patients’ distribution map was displayed in Fig.5. On this map, it is hard to see the relation between mining and waste sites with the location of patients’ occurring. But, after overlay of surface soil type, arsenic level in groundwater, arsenic level in surface soil, it shows that the patients appear only at the area with sandy surface soil and arsenic level in shallow or deep groundwater above 50ppb, arsenic in soil elution above 50 ppb. The arsenic level in shallow and deep groundwater within the zone of arsenism patient is significantly higher than outside zone, while the difference of arsenic level in surface soil elution inside or outside the patients’ zone is not significant (Table 4). This indicates the major pathway of arsenism is through drinking water, while the inhalation and ingestion of soil dust may be less important. 3.5 DYNAMIC CHANGES OF ARSENIC LEVEL IN SHALLOW GROUNDWATER IN DRY AND RAINY SEASON In order to observe the arsenic pollution situation between dry and rainy season, the interpolated map of arsenic level in shallow groundwater in both seasons was compared. In dry season, the mean arsenic level is 1.06 ppm with the highest value 13 ppm. The area with arsenic level higher than 50 ppb is 8,372,075 m 2 occupies 99.57% of the total interpolated area. Comparing with rainy season, the polluted area increases by 2,291,625 m 2 . The reason why the arsenic pollution extends from rainy season to dry season is supposed as: in rainy season, the recharge of groundwater from precipitation is huge, at the mean time, arsenic amount flushed into surface runoff and eventually into groundwater increase simultaneously. But, due to the huge volume of groundwater, the mean arsenic level in groundwater is relatively low. While in the dry season, recharge to groundwater is low and évapotranspiration became huge. This results in the relatively higher arsenic level in groundwater. The extension of arsenic containing aquifer area is contributed to the dispersion of groundwater along its flow direction. Considering the arsenic- increasing location of groundwater, it is found that most of such locations are at the eastern part of study area where is a plain area and the groundwater flow velocity is slow. But the clearer mechanism of pollution extension is far more complex than this, which needs further study later. 3.6 ARSENIC LEVEL IN SURFACE WATER 40 river water samples and 5 pond water samples were taken for the measurement of total arsenic. The arsenic level In river water is from 0.02 to 0.62 ppm, mean value 0.11 ppm, pond arsenic from 0.04 to1.1 ppm, mean value 0.33ppm. Because the exchange between river and groundwater, river may interfere the groundwater arsenic concentration in some extent. Table 5 shows that within 600 meters, groundwater arsenic is decreasing significantly with the increasing of distance to river. 4. CONCLUSIONS The arsenic pollution situation in Ron Phibun district, Nakhorn Si Thammarat Province was depicted with GIS help. The groundwater arsenic concentrations had a large distribution ranging from 0 to 64 ppm throughout the study area. The mappings of the groundwater arsenic concentrations in study area showed that groundwater arsenic concentrations tend to be higher in the vicinity of mining waste and dump sites than the other parts. These were approved to be the arsenic pollution sources in study area. Taking into consideration of all measured environmental media, shallow groundwater, deep groundwater, the pollution situation was rather severe based on the WHO recommended drinking water limit (0.05mg/L). Due to the lack of standard of soil arsenic and background arsenic value in study area, the arsenic level of soil elution in this study is only of reference for arsenic contamination. The GIS database could be used for the local government to guide the action for arsenic alleviating, monitoring of arsenic level, provide support for decision-making. As to the severity of arsenic pollution in groundwater, it is strongly suggested that the groundwater should be treated efficiently to lower the arsenic level in it. Mining waste and dump as well as the contaminated soil should also be removed out in order to get rid of the pollution sources. Alternative drinking water must be found because of the current high arsenic content in groundwater. 5. ACKNOWLEDGES The authors gratefully acknowledge the ERTCTThailand for providing data on arsenic level in surface and groundwater, soil and geological information. We thank the STAR/AIT program for providing GIS process facilities 6. REFERENCES Ahmadul Hassan and Timothy Martin, Spatial information systems for arsenic mitigation programs( International conference on arsenic pollution of ground water in Bangladesh: causes, effects and remedies, Abstracts Date: 8-

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