Pollution assessment of heavy metals along the Mekong River and dam effects

doi:10.1007/s11442-012-0969-3

Abstract

Abstract:

The resource development and changes of hydrological regime, sediment and water quality in the Mekong River basin have attracted great attentions. This research aimed to enhance the study on transboundary pollution of heavy metals in this international river. In this study, eight sampling sites were selected to collect the bed sand samples along the mainstream of the Mekong River. In addition, the contents of 5 heavy metal elements and their spatial variability along the mainstream of the river were analyzed. The geoaccumulation index (I_geo) and potential ecological risk analysis were employed to assess heavy metal pollution status in the mainstream of the Mekong River. The results show that the average content of the heavy metal elements Zn is 91.43 mg/kg, Pb is 41.85 mg/kg, and As is 21.84 mg/kg in the bed sands of the Upper Mekong River, which are higher than those (Zn 68.17 mg/kg, Pb 28.22 mg/kg, As 14.97 mg/kg) in the Lower Mekong. The average content of Cr in the Lower Mekong is 418.86 mg/kg, higher than that in the Upper Mekong (42.19 mg/kg). Luang Prabang has a very high Cr concentration with 762.93 mg/kg and Pakse with 422.90 mg/kg. The concentration of Cu in all of the 8 sampling sites is similar, except for in Jiajiu with 11.70 mg/kg and Jiebei with 7.00 mg/kg. The results of the geoaccumulation index reveal that contaminations caused by Zn and Pb while Pb and As are more than those by Zn in Upper Mekong. Cr is the primary pollutant in the Lower Mekong, especially at Luang Prabang and Pakse. Slight pollution with As also occurs in Pakse. The potential ecological risk index indicates that the potential ecological risk of heavy metals in the mainstream of the Mekong River is low. We argue that the pollution of water quality and contamination of heavy metals in bed sediment caused by mining of mineral resources or geochemical background values in the Mekong is not transmitted from the Upper to the Lower Mekong because of the reservoir sedimentation and dilution along the river.

Key words: Mekong River basin, heavy metal pollution, geoaccumulation index, potential ecological risk index

FU Kaidao, SU Bin, HE Daming, LU Xixi, SONG Jingyi, HUANG Jiangcheng. Pollution assessment of heavy metals along the Mekong River and dam effects[J].Journal of Geographical Sciences, 2012, 22(5): 874-884.

References

Anna F, Claudio E, Luigi V, 2007. Assessment of the environmental significance of heavy metal pollution in surficial sediments of the River Po. Chemosphere, 68: 761-768.
Bettinetti R, Giarei C, Provini A, 2003. A chemical analysis and sediment toxicity bioassays to assess the contamination of the River Lambro (Northern Italy). Archives of Environmental Contamination and Toxicology, 45: 72-80.
Chapman P M, 2000. The sediment quality triad: Then, now and tomorrow. International Journal of Environment and Pollution, 13: 351-360.
Chen F, 1999. Status quo and influence of water quality in the basin of Lancang River. Yunnan Environmental Science, 18(1): 47-49. (in Chinese)
Chen J S, Zhou J Y, 1992. The Research of Heavy Metals in Water Environment of China. Beijing: China Environmental Science Press, 168-170. (in Chinese)
Chen Q, Kong X S, 2000. Lancang-Mekong River Basin Basic Data Collection. Kunming: Yunnan Scientific and Technical Publishers, 1-8. (in Chinese)
Chris S, Coleen F, 2006. Rethinking transboundary waters: A critical hydropolitics of the Mekong basin. Political Geography, 25: 181-202.
Corinna K, Jürgen W E, 2006. Modern chemometric data analysis: Methods for the objective evaluation of load in river systems. Acta Hydrochem. Hydrobiol., 34: 425-435.
Ding Z H, Jia H W, Li C E, 2006. Pollution and assessment of heavy metals in Huangpu River sediments. Environmental Science and Technology, 29(2): 64-66. (in Chinese)
Edwin D Ongley, 2009. Water quality of the lower Mekong River. In: Ian C Campbell (eds.). The Mekong Biophysical Environment of an International River Basin. New York: Elsevier Academic Press, 297-319.
Fu K D, He D M, 2007. Analysis and prediction of sediment trapping efficiencies by dams on mainstream of Lancang River. Chinese Science Bulletin, 52: 134-140
Fu K D, He D M, Lu X X, 2008. Sedimentation in the Manwan Reservoir in the Upper Mekong and its downstream impacts. Quaternary International, 186, 91-99.
Forstner U, 1989. Lecture Notes in Earth Sciences (Contaminated Sediments). Berlin: Springer Verlag, 107-109
Gerard K, Bertil V O, 2007. Influence of hydropower dams on the composition of the suspended and riverbank sediments in the Danube. Environmental Pollution 148, 718-728.
Gibbs R J, 1972.Water chemistry of the Amazon River. Geochimicaet Cosmochimica Acta, 36: 1061-1066.
Habes G, Nigem Y, 2006. Assessing Mn, Fe, Cu, Zn, and Cd pollution in bottom sediments of Wadi Al-Arab Dam, Jordan. Chemosphere, 65: 2114-2121.
H?kanson L, 1980. An ecological risk index for aquatic pollution control of sediment ecological approach. Water Research, 14: 975-1000.
He D M, Feng Y, 2006. Rational Utilization and Coordination Management of Transboundary Water Resources in the International River. Beijing: Science Press, 20-47.
He D M, Wu S H, Peng H, 2005. A study of ecosystem changes in longitudinal range-gorge region and transboundary eco-security in Southwest China. Advances in Earth Science, 20(3): 338-344. (in Chinese)
He G J, Li J F, Gu L P, 2007. Pollution situation and control progress of heavy mental in the bottom sediment of the river. Reservoir Fisheries, 27(5): 60-62. (in Chinese)
Hilton D W, Ochsenbein U A, 1985. Mathematical model for analysis of sediment core data: Implications for enrichment factor calculation and trace metal transport mechanisms. Chemical Geology, 48: 281-291.
Hollert H, Keiter S, Konig N et al., 2003. A new sediment contact assay to assess particulate-bound pollutants using Zebrafish (Daniorerio) embryos. Journal of Soils and Sediments, 3: 197-207.
Horst M F, 1997. Heavy metal distribution in sediments and ecological risk assessment: The role of diagenetic processes in reducing metal toxicity in bottom sediments. Environmental Pollution, 3: 317-325.
Hu G H, Zhao P L, Xiao X Q, 2004. Sediment characteristics of Yellow River and their influence on water environment. Water Resources and Hydropower Engineering, 35(8): 17-20. (in Chinese)
Huang J C, Fu K D, He D M, 2010. Analysis on the characteristics of sediment in the middle and lower parts of the Lancang River. Journal of Sichuan University (Engineering Science Edition), 42(3): 112-119. (in Chinese)
Ian C Campbell, 2009. Introduction. In: Ian C Campbell (eds.). The Mekong Biophysical Environment of an International River Basin. New York: Elsevier Academic Press, 1-9.
Jia Z B, Yu P T, 1995. Using Excess after Regression Analysis (ERA) method to evaluate heavy metal pollution in the Taizi River of Benxi City. Acta Scientiarum Naturalium Universitatis Pekinensis, 31(4): 451-458. (in Chinese)
Jiang B Y, Wang L L, 2009. Research status of heavy mental pollution in the sediment in water system of China. Science and Technology Information, 9: 383. (in Chinese)
Li L J, 1999.Water quality status assessment and causal analysis of Lancang River. Acta Geographica Sinica, 54(suppl.): 127-131. (in Chinese)
Lokeshwari H, Chandrappa G T, 2007. Effects of heavy metal contamination from anthropogenic sources on Dasarahallitank, India. Research and Management, 12: 121-128.
Luoma S N, Bryan G W, 1981. A statistical assessment of the form of trace metals in oxidized estuarine sediments employing chemical extractants. The Science of the Total Environment, 17: 165-196.
MacFarlane G R, Burchett M D, 2000. Cellular distribution of Cu, Pb and Zn in the Grey Mangrove Avicennia marina (Forsk) Vierh. Aqume Botany, 68: 45-59.
Memet V, 2011. Assessment of heavy metal contamination in sediments of the Tigris River (Turkey) using pollution indices and multivariate statistical techniques. Journal of Hazardous Materials, 195: 355-364.
Muller G, 1969. Index of geoaccumulation in sediments of the Rhine River. Geological Journal, 2: 109-118.
Rodríguez-Barroso M R, García-Morales J L, Coello Oviedo M D et al., 2010. An assessment of heavy metal contamination in surface sediment using statistical analysis. Environ. Monit. Assess., 163: 489-501.
Schuurmann G, Market B, 1997. Ecotoxicology, Ecological Fundamentals, Chemical Exposure, and Biological Effects. John Wiley & Sons Inc, and Spektrum Akademischer Verlag, 936.
Su Y L, 2004. Initial exploration of overall prevention and control countermeasures for pollution and danger in Bi Jiang River. Yunnan Environmental Science, 23: 118-119. (in Chinese)
Takahiro H, Chih-Chieh S, Kei O et al., 2010. Historical record of heavy metal pollution deduced by lead isotope ratios in core sediments from the Osaka Bay, Japan. Journal of Geochemical Exploration, 107: 1-8.
Tomlinson D C, Wilson J G, Harris CR et al., 1980. Problems in the assessment of heavy metals levels in estuaries and the formation of a pollution index. Helgolander Meeresunters, 33: 566-575.
Turekian K K, Wedepohl K H, 1961. Distribution of the elements in some major units of the earth’s crust. Geological Society of America Bulletin, 72: 175-192.
Van de Guchte C, 1992. The sediment quality triad: An integrated approach to assess contaminated sediments. In: Newman P J, Piavaux M A, Sweeting R A (eds.), River Water Quality. Ecological Assessment and Control. Brussels: ECSC-EEC-EAEC, 417-423.
Wang Y J, Lu W Y, Liu G G, 2009. Progress in research on heavy metal speciation and bioavailability in sediment. Safety and Environmental Engineering, 16(4): 27-29. (in Chinese)
Wei F S, 1990. Background Values of Elements in Soils of China. Beijing: China Environmental Science Press, 330-482. (in Chinese)
Xu Z Q, Ni S J, Tuo X G, 2008. Calculation of heavy metals’ toxicity coefficient in the evaluation of potential ecological risk index. Environmental Science and Technology, 31(2): 112-114. (in Chinese)
Yi Y J, Yang Z F, Zhang S H, 2011. Ecological risk assessment of heavy metals in sediment and human health risk assessment of heavy metals in fishes in the middle and lower reaches of the Yangtze River Basin. Environmental Pollution, 159: 2575-2585.
Zhou X Y, Wang E D, 2004, Method on how to apply index of geoaccumulation to evaluate heavy metal pollution as result of index of inter-tidal sediment in Liaodong Bay. Journal of Safety and Environment, 4(2): 22-23. (in Chinese)
Zhu L Y, Deng B L, Liu N N, 2009. Application of equilibrium partitioning approach to derive sediment quality criteria for heavy metals. Research of Environmental Sciences, 22(7): 763-766. (in Chinese)