Abstract
To investigate the potential health risk of trace elements in the Tonle Sap Great Lake system, lake (n = 37) and river (n = 14) water samples were collected and analyzed for 19 trace elements (Ag, Al, As, B, Ba, Cd, Co, Cr, Cu, Fe, Ga, Mn, Mo, Ni, Pb, Se, Tl, U and Zn) using inductively coupled plasma mass spectrometry. As a result, Cd was not detected in any river and lake water samples. Al, Fe and Mn in lake water exceeded the regulation limits of Cambodia, USEPA and WHO. Health risk assessment using the USEPA model indicated that male and female Cambodian residents are at minimal risk of non-carcinogenic effects from single and mixed trace elements through lake and river water consumption. Nevertheless, As, Tl, Co, Ba, Mn and Cr might pose high potential health risks to consumers which requires more attention. Therefore, regular monitoring and further studies are required to investigate the pollution trends and toxic behavior of these trace elements in the Tonle Sap Great Lake system.
HIGHLIGHTS
We investigated the distribution of 19 trace elements in the Tonle Sap Great Lake system.
As, B, Cu, Mo, Ni, Se and U in the Great Lake were higher than those in the river.
Ag, As, B, Ba, Cu, Ga, Mn and Se were significantly different among the five provinces.
Residents did not have the non-carcinogenic effect of trace elements through lake and river water consumption.
INTRODUCTION
Contamination by trace elements has created substantial concern among environmental scientists. Although some trace elements are essential for the normal growth of humans and animals, high intake and low intake of essential trace elements can lead to toxicity and nutritional deficiency, respectively (Goldhaber 2003). For instance, trace elements in drinking water (Kavcar et al. 2009) and food grains grown in contaminated soils (Huang et al. 2008) can pose significant non-carcinogenic effects on their consumers. Ecological communities and living organisms in receiving water are also affected by the direct discharge of effluents from various industries into aquatic systems (Krishna et al. 2009). The Tonle Sap Great Lake is the largest freshwater lake in SE Asia, and hosts one of the most productive inland fisheries in the world, accounting for more than 75% of Cambodia's inland fish catch and 60% of the country's protein needs (Burnett et al. 2013). The temperature in Cambodia is likely to rise by between 0.13 and 0.36 °C per decade while rainfall patterns are not clear with some increase in average rainfall in hilly areas in the wet season and a decrease in the dry season (NCCC 2013). The rainfall distribution in Cambodia is strongly influenced by her topography and seasonal monsoons resulted in the highest rainfall (2,000–3,400 mm) occurring in the southwest in coastal areas followed by the northeast plateau area (1,800 to >2,200 mm) and the stretches from the northwest to the southeast which receives annual rainfall of <1,400 mm (Sok & Chuop 2017). Recently, many food industries and factories have been located on the bank of the Tonle Sap River. Industrialization and population growth along the river are believed to be major distributors of trace elements in the Tonle Sap River (Chanpiwat & Sthiannopkao 2014). In general, Cambodian residents living along the Tonle Sap River downstream of Phnom Penh rely on the river water, whereas those living around the Tonle Sap Great Lake rely on the lake water as a main source of their water supply. Although conventional water quality parameters had been continuously monitored (Irvine et al. 2011), a few assessments of trace element contaminations in the Tonle Sap River (Chanpiwat & Sthiannopkao 2014) and Tonle Sap Great Lake (Ki et al. 2009) of Cambodia have been conducted to date. On the other hand, health risk assessment of trace elements of residents who drink the river and lake water has not yet been conducted. The overall objective of the present project was to investigate the distribution of trace elements in the Tonle Sap Great Lake and the Tonle Sap River in Cambodia and assess the health risks of residents who drink these waters. Specifically, it was to (1) determine the distribution of trace elements in the five surrounding provinces of the Tonle Sap Great Lake of Cambodia, (2) compare the concentration of trace elements among the five surrounding provinces, (3) compare the concentrations of trace elements in the Great Lake and its tributary and (4) assess the human health risk of trace elements through drinking water from the Tonle Sap River and the Tonle Sap Great Lake.
MATERIALS AND METHODS
Field work
Sample analyses
All chemical measurements were employed by inductively coupled plasma mass spectroscopy (ICP-MS, Agilent 7500 ce) using an external calibration method. Working standard solutions were prepared in a proper range of ICP-MS (0, 0.1, 1, 5, 10, 20, 50, 100 μg L−1). For the solvent to use in solution preparation, and analytical procedures, 2% HNO3 (percent by volume) was prepared from 18.2 MΩ cm−1 deionized water obtained from a Millipore Milli-Q water purification system. The possibility of trace metal contamination in the 2% HNO3 was also checked and reported as an analytical blank. A standard reference material (Trace Element in Water, SRM 1643e) was analyzed to check the ICP-MS accuracy. If the recovery rate was out of the recommended range (90–110%), samples were reanalyzed with a new calibration curve.
Health risk assessment
HI is a hazard index which indicated the aggregate risk/risk of mixed trace elements. Non-carcinogenic effects of mixed trace elements are considered to occur in a circumstance where HI is greater than one.
Statistical data analyses
All statistical data analyses were performed by SPSS for Windows (Version 16.0). One-Way ANOVA tests and post hoc tests were conducted to certify the difference in trace element concentrations among the five surrounding provinces of the Tonle Sap Great Lake. An independent samples t-test was applied to access the difference in trace element concentrations in the Great Lake and its tributary.
RESULTS AND DISCUSSION
Distribution of trace elements in the Great Lake and its tributary
All chemical measurements of trace elements in the Tonle Sap River and the Tonle Sap Great Lake are presented in Table 1. Cadmium was not detected in any lake (n = 37) and river (n = 14) water samples. Trace elements in the Tonle Sap River ranged from 0.006 μg L−1 (Tl) to 169.80 μg L−1 (Fe), whereas trace elements in the Tonle Sap Great Lake ranged from 0.002 μg L−1 (Ag) to 2,453.00 μg L−1 (Al). As and Zn concentrations in the Tonle Sap River were up to 2.2 and 6.45 times, respectively, higher than the average levels in the world natural rivers. The present findings were consistent with the previous ones reported by Chanpiwat & Sthiannopkao (2014). Likewise, As and Pb concentrations in the Tonle Sap Great Lake were up to 3 and 12.8 times, respectively, greater than the average levels in the world natural rivers. The mean concentrations of other trace elements in both Tonle Sap River and Great Lake were below the average levels of world natural rivers. Another comparison indicated that none of the trace elements in river water exceeded the regulation limits of Cambodia, WHO and USEPA. Likewise, most of the trace elements in lake water were lower than the regulation limits, except Al, Fe and Mn. The concentrations of Al, Fe and Mn in the Tonle Sap Great Lake in the present study were comparable to those reported by Ki et al. (2009). The sources of trace elements in the Tonle Sap River were more likely from the discharge of municipal sewage wastewater into the river (Chanpiwat & Sthiannopkao 2014). Since water flows from the connecting tributary to the Great Lake during the wet monsoon season, trace elements in the Tonle Sap River water can be transported and deposited in the Great Lake. Further investigations on temporal and spatial variations of trace elements in the Great Lake and its tributaries are required to better understand their pollution trends and toxic behaviors which may impact the ecological system of the Tonle Sap Great Lake.
Summary of trace elements (μg L−1) in the Tonle Sap River, Tonle Sap Lake, and world natural river, and their regulation limit by the World Health Organization (WHO), US Environmental Protection Agency (USEPA), and Cambodia
. | Tonle Sap River (n = 14) . | Tonle Sap Lake (n = 37) . | World natural rivera . | Regulation limit . | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Elements . | LOD . | Mean . | Median . | SD . | Min . | Max . | Mean . | Median . | SD . | Min . | Max . | Average . | SD . | WHOb . | USEPAc . | Cambodiad . |
Ag | 0.001 | 0.81 | 0.87 | 0.29 | 0.41 | 1.21 | 0.79 | 0.22 | 1.39 | 0.002 | 5.48 | – | – | – | 100 | – |
Al | 0.261 | 11.26 | 5.92 | 13.07 | 3.59 | 45.55 | 86.23 | 16.59 | 400.23 | 3.91 | 2,453.00 | 32.00 | 179.00 | 200 | 200 | 200 |
As | 0.005 | 0.69 | 0.64 | 0.18 | 0.59 | 1.31 | 1.16 | 1.17 | 0.27 | 0.70 | 1.78 | 0.60 | 0.60 | 10 | 10 | 50 |
B | 0.101 | 5.50 | 5.37 | 0.49 | 5.19 | 7.15 | 10.11 | 12.52 | 3.51 | 5.70 | 14.48 | – | – | 500 | – | – |
Ba | 0.008 | 19.47 | 19.21 | 1.18 | 18.27 | 22.89 | 20.38 | 18.74 | 5.33 | 14.14 | 37.22 | 23.00 | 13.50 | 700 | 200 | 700 |
Cd | 0.011 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | 0.10 | 0.10 | 3 | 5 | 3 |
Co | 0.001 | 0.06 | 0.06 | 0.01 | 0.05 | 0.09 | 0.11 | 0.05 | 0.24 | 0.03 | 1.30 | 0.20 | 0.10 | 40 | – | – |
Cr | 0.013 | 0.08 | 0.05 | 0.08 | 0.01 | 0.27 | 0.19 | 0.11 | 0.42 | 0.01 | 2.32 | 0.90 | 2.80 | 50 | 100 | 50 |
Cu | 0.010 | 0.81 | 0.76 | 0.17 | 0.61 | 1.20 | 1.29 | 1.39 | 0.63 | 0.26 | 3.14 | 1.50 | 0.70 | 2,000 | 1,300 | 1,000 |
Fe | 0.292 | 21.30 | 5.24 | 45.02 | 2.37 | 169.80 | 111.37 | 30.82 | 331.29 | 11.40 | 2,041.00 | 66.00 | 185.90 | 300 | 300 | 300 |
Ga | 0.003 | 4.02 | 3.91 | 0.28 | 3.83 | 4.80 | 3.97 | 3.84 | 0.99 | 2.76 | 7.13 | – | – | – | – | – |
Mn | 0.001 | 9.21 | 8.11 | 3.50 | 5.43 | 17.11 | 13.49 | 2.07 | 37.01 | 0.27 | 220.10 | 34.00 | 12.50 | – | 50 | 100 |
Mo | 0.010 | 0.14 | 0.13 | 0.04 | 0.10 | 0.26 | 0.21 | 0.21 | 0.04 | 0.12 | 0.33 | 0.40 | 0.50 | 70 | – | – |
Ni | 0.021 | 0.19 | 0.15 | 0.07 | 0.13 | 0.36 | 0.38 | 0.33 | 0.30 | 0.14 | 2.02 | 0.80 | 2.20 | 70 | – | 20 |
Pb | 0.004 | 0.10 | 0.07 | 0.09 | 0.01 | 0.30 | 0.13 | 0.08 | 0.21 | 0.02 | 1.28 | 0.10 | 0.90 | 10 | 15 | 10 |
Se | 0.017 | 0.06 | 0.06 | 0.01 | 0.04 | 0.08 | 0.08 | 0.08 | 0.03 | 0.03 | 0.14 | – | – | 10 | 50 | 10 |
Tl | 0.004 | 0.008 | 0.008 | 0.001 | 0.006 | 0.011 | 0.008 | 0.008 | 0.004 | 0.004 | 0.029 | – | – | – | 2 | – |
U | 0.001 | 0.02 | 0.02 | 0.01 | 0.02 | 0.04 | 0.03 | 0.03 | 0.01 | 0.01 | 0.09 | – | – | 15 | 30 | – |
Zn | 0.052 | 3.87 | 1.50 | 6.94 | 0.49 | 26.67 | 1.98 | 1.62 | 1.27 | 0.45 | 5.08 | 0.60 | 4.60 | 3,000 | 5,000 | 3,000 |
. | Tonle Sap River (n = 14) . | Tonle Sap Lake (n = 37) . | World natural rivera . | Regulation limit . | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Elements . | LOD . | Mean . | Median . | SD . | Min . | Max . | Mean . | Median . | SD . | Min . | Max . | Average . | SD . | WHOb . | USEPAc . | Cambodiad . |
Ag | 0.001 | 0.81 | 0.87 | 0.29 | 0.41 | 1.21 | 0.79 | 0.22 | 1.39 | 0.002 | 5.48 | – | – | – | 100 | – |
Al | 0.261 | 11.26 | 5.92 | 13.07 | 3.59 | 45.55 | 86.23 | 16.59 | 400.23 | 3.91 | 2,453.00 | 32.00 | 179.00 | 200 | 200 | 200 |
As | 0.005 | 0.69 | 0.64 | 0.18 | 0.59 | 1.31 | 1.16 | 1.17 | 0.27 | 0.70 | 1.78 | 0.60 | 0.60 | 10 | 10 | 50 |
B | 0.101 | 5.50 | 5.37 | 0.49 | 5.19 | 7.15 | 10.11 | 12.52 | 3.51 | 5.70 | 14.48 | – | – | 500 | – | – |
Ba | 0.008 | 19.47 | 19.21 | 1.18 | 18.27 | 22.89 | 20.38 | 18.74 | 5.33 | 14.14 | 37.22 | 23.00 | 13.50 | 700 | 200 | 700 |
Cd | 0.011 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | 0.10 | 0.10 | 3 | 5 | 3 |
Co | 0.001 | 0.06 | 0.06 | 0.01 | 0.05 | 0.09 | 0.11 | 0.05 | 0.24 | 0.03 | 1.30 | 0.20 | 0.10 | 40 | – | – |
Cr | 0.013 | 0.08 | 0.05 | 0.08 | 0.01 | 0.27 | 0.19 | 0.11 | 0.42 | 0.01 | 2.32 | 0.90 | 2.80 | 50 | 100 | 50 |
Cu | 0.010 | 0.81 | 0.76 | 0.17 | 0.61 | 1.20 | 1.29 | 1.39 | 0.63 | 0.26 | 3.14 | 1.50 | 0.70 | 2,000 | 1,300 | 1,000 |
Fe | 0.292 | 21.30 | 5.24 | 45.02 | 2.37 | 169.80 | 111.37 | 30.82 | 331.29 | 11.40 | 2,041.00 | 66.00 | 185.90 | 300 | 300 | 300 |
Ga | 0.003 | 4.02 | 3.91 | 0.28 | 3.83 | 4.80 | 3.97 | 3.84 | 0.99 | 2.76 | 7.13 | – | – | – | – | – |
Mn | 0.001 | 9.21 | 8.11 | 3.50 | 5.43 | 17.11 | 13.49 | 2.07 | 37.01 | 0.27 | 220.10 | 34.00 | 12.50 | – | 50 | 100 |
Mo | 0.010 | 0.14 | 0.13 | 0.04 | 0.10 | 0.26 | 0.21 | 0.21 | 0.04 | 0.12 | 0.33 | 0.40 | 0.50 | 70 | – | – |
Ni | 0.021 | 0.19 | 0.15 | 0.07 | 0.13 | 0.36 | 0.38 | 0.33 | 0.30 | 0.14 | 2.02 | 0.80 | 2.20 | 70 | – | 20 |
Pb | 0.004 | 0.10 | 0.07 | 0.09 | 0.01 | 0.30 | 0.13 | 0.08 | 0.21 | 0.02 | 1.28 | 0.10 | 0.90 | 10 | 15 | 10 |
Se | 0.017 | 0.06 | 0.06 | 0.01 | 0.04 | 0.08 | 0.08 | 0.08 | 0.03 | 0.03 | 0.14 | – | – | 10 | 50 | 10 |
Tl | 0.004 | 0.008 | 0.008 | 0.001 | 0.006 | 0.011 | 0.008 | 0.008 | 0.004 | 0.004 | 0.029 | – | – | – | 2 | – |
U | 0.001 | 0.02 | 0.02 | 0.01 | 0.02 | 0.04 | 0.03 | 0.03 | 0.01 | 0.01 | 0.09 | – | – | 15 | 30 | – |
Zn | 0.052 | 3.87 | 1.50 | 6.94 | 0.49 | 26.67 | 1.98 | 1.62 | 1.27 | 0.45 | 5.08 | 0.60 | 4.60 | 3,000 | 5,000 | 3,000 |
LOD, limit of detection; N/A, not applicable because it is below LOD; SD, standard deviation; Min, minimum; Max, maximum.
aAdapted from Chanpiwat & Sthiannopkao 2014.
bWHO 2011.
Comparisons of trace elements in the Great Lake and its tributary
The t-tests revealed that there were no significant differences in Ag, Al, Ba, Co, Cr, Fe, Ga, Mn, Pb, Tl and Zn in the Tonle Sap Great Lake and its tributary river (p > 0.05; Table 2). However, As, B, Cu, Mo, Ni, Se and U concentrations in the Great Lake were significantly higher than those in the river (t-test, p < 0.05; Table 2). Ki et al. (2009) revealed that concentrations of trace elements in the Tonle Sap Great Lake were generally higher than those in other water systems because it is the final depository. There were also significant differences in Ag, As, B, Ba, Cu, Ga, Mn and Se among the five surrounding provinces of the Great Lake (one-way ANOVA, p < 0.05; Table 3). Nevertheless, Al, Co, Cr, Fe, Mo, Ni, Pb, Tl, U and Zn were not significantly different among the five provinces (one-way ANOVA, p > 0.05; Table 3). Games–Howell post hoc test indicated there were no significant differences in Ag among Siem Reap, Battambang, Pursat, Kampong Chhnang and Kampong Thom (p > 0.05). There were significant differences in B, Cu and Se between Siem Reap and Pursat, Kampong Chhnang and Kampong Thom, between Battambang and Pursat, and between Kampong Chhnang and Kampong Thom (p < 0.05). Likewise, there were significant differences in Ga among Siem Reap and Pursat and Kampong Chhnang and between Pursat and Kampong Chhnang (p < 0.05). There was a significant difference in Mn between Siem Reap and Pursat (p < 0.05). The Tukey HSD (honestly significant difference) test indicated that As was significantly different among Kampong Chhnang and Battambang and Kampong Thom (p < 0.05). There were significant differences in Ba between Siem Reap and Pursat, Kampong Chhnang and Kampong Thom and between Battambang and Pursat, Kampong Chhnang and Kampong Thom as well as between Pursat and Kampong Thom (p < 0.05). The differences in metal concentrations between sampling locations of the same lake have been found in the literature. For instance, Oyoo-Okoth et al. (2013) reported that the mean concentrations of Cd, Co, Cr, Cu, Ti and Zn in lake water were significantly different in locations of Lake Victoria, Kenya. Concurrently, the mean concentrations of Cu, Zn, Cd, Pb, Co, and Fe in lake water were found significantly different between locations of Lake Titicaca, South America (Monroy et al. 2014). When compared to lakes in other countries (Table 4), it indicated that the mean concentrations of Co, Cr, Cu, Pb and Zn in water of the Tonle Sap Great Lake were lower than those in the Rawal Lake, Pakistan in summer, reported by Iqbal et al. (2013). It was also apparent that mean concentrations of Cu, Pb and Zn in water of the Tonle Sap Great Lake were much lower than those in the Lake Dalinouer, China (Hou et al. 2013) and mean concentrations of As, Cr, Cu, Ni, Pb and Zn were lower than those in the Taihu Lake, China (Jiang et al. 2012). Although Fe and Co concentrations in lake water were similar between the Tonle Sap Great Lake and the Lake Titicaca (Monroy et al. 2014), the concentrations of Cu, Pb and Zn in water of the Tonle Sap Great Lake were relatively lower. The mean concentrations of Pb, Cr and Cu in water of the Tonle Sap Great Lake were much lower than those in Lake Victoria, Kenya, reported by Oyoo-Okoth et al. (2010).
Comparison of trace elements in the Tonle Sap Great lake and Tonle Sap River
Variable . | Mean . | SD . | t . | df . | p . |
---|---|---|---|---|---|
Aga | 0.055 | 31.214 | 0.956 | ||
River | 0.806 | 0.290 | |||
Great lake | 0.790 | 1.392 | |||
Al | −0.696 | 49 | 0.489 | ||
River | 11.26 | 13.07 | |||
Great lake | 86.23 | 400.23 | |||
Asa | −7.084 | 35.265 | <0.01 | ||
River | 0.686 | 0.182 | |||
Great lake | 1.155 | 0.273 | |||
Ba | −7.793 | 39.507 | <0.01 | ||
River | 5.499 | 0.489 | |||
Great lake | 10.107 | 3.508 | |||
Baa | −0.983 | 43.896 | 0.331 | ||
River | 19.469 | 1.181 | |||
Great lake | 20.384 | 5.331 | |||
Co | −0.759 | 49 | 0.451 | ||
River | 0.060 | 0.013 | |||
Great lake | 0.109 | 0.243 | |||
Cr | −0.941 | 41 | 0.352 | ||
River | 0.085 | 0.078 | |||
Great lake | 0.191 | 0.416 | |||
Cua | −4.222 | 46.39 | <0.01 | ||
River | 0.811 | 0.169 | |||
Great lake | 1.286 | 0.627 | |||
Fe | −1.008 | 49 | 0.319 | ||
River | 21.30 | 45.02 | |||
Great lake | 111.37 | 331.29 | |||
Gaa | 0.318 | 46.93 | 0.752 | ||
River | 4.025 | 0.279 | |||
Great lake | 3.968 | 0.995 | |||
Mn | −0.429 | 49 | 0.67 | ||
River | 9.21 | 3.50 | |||
Great lake | 13.49 | 37.01 | |||
Mo | −5.333 | 49 | <0.01 | ||
River | 0.142 | 0.037 | |||
Great lake | 0.205 | 0.038 | |||
Ni | −2.416 | 49 | 0.019 | ||
River | 0.185 | 0.070 | |||
Great lake | 0.384 | 0.303 | |||
Pb | −0.446 | 49 | 0.657 | ||
River | 0.105 | 0.094 | |||
Great lake | 0.131 | 0.207 | |||
Sea | −4.003 | 48.864 | <0.01 | ||
River | 0.056 | 0.011 | |||
Great lake | 0.079 | 0.029 | |||
Tl | −0.564 | 49 | 0.575 | ||
River | 0.008 | 0.001 | |||
Great lake | 0.008 | 0.004 | |||
U | −2.159 | 49 | 0.036 | ||
River | 0.022 | 0.006 | |||
Great lake | 0.029 | 0.012 | |||
Zna | 1.013 | 13.331 | 0.329 | ||
River | 3.867 | 6.939 | |||
Great lake | 1.978 | 1.271 |
Variable . | Mean . | SD . | t . | df . | p . |
---|---|---|---|---|---|
Aga | 0.055 | 31.214 | 0.956 | ||
River | 0.806 | 0.290 | |||
Great lake | 0.790 | 1.392 | |||
Al | −0.696 | 49 | 0.489 | ||
River | 11.26 | 13.07 | |||
Great lake | 86.23 | 400.23 | |||
Asa | −7.084 | 35.265 | <0.01 | ||
River | 0.686 | 0.182 | |||
Great lake | 1.155 | 0.273 | |||
Ba | −7.793 | 39.507 | <0.01 | ||
River | 5.499 | 0.489 | |||
Great lake | 10.107 | 3.508 | |||
Baa | −0.983 | 43.896 | 0.331 | ||
River | 19.469 | 1.181 | |||
Great lake | 20.384 | 5.331 | |||
Co | −0.759 | 49 | 0.451 | ||
River | 0.060 | 0.013 | |||
Great lake | 0.109 | 0.243 | |||
Cr | −0.941 | 41 | 0.352 | ||
River | 0.085 | 0.078 | |||
Great lake | 0.191 | 0.416 | |||
Cua | −4.222 | 46.39 | <0.01 | ||
River | 0.811 | 0.169 | |||
Great lake | 1.286 | 0.627 | |||
Fe | −1.008 | 49 | 0.319 | ||
River | 21.30 | 45.02 | |||
Great lake | 111.37 | 331.29 | |||
Gaa | 0.318 | 46.93 | 0.752 | ||
River | 4.025 | 0.279 | |||
Great lake | 3.968 | 0.995 | |||
Mn | −0.429 | 49 | 0.67 | ||
River | 9.21 | 3.50 | |||
Great lake | 13.49 | 37.01 | |||
Mo | −5.333 | 49 | <0.01 | ||
River | 0.142 | 0.037 | |||
Great lake | 0.205 | 0.038 | |||
Ni | −2.416 | 49 | 0.019 | ||
River | 0.185 | 0.070 | |||
Great lake | 0.384 | 0.303 | |||
Pb | −0.446 | 49 | 0.657 | ||
River | 0.105 | 0.094 | |||
Great lake | 0.131 | 0.207 | |||
Sea | −4.003 | 48.864 | <0.01 | ||
River | 0.056 | 0.011 | |||
Great lake | 0.079 | 0.029 | |||
Tl | −0.564 | 49 | 0.575 | ||
River | 0.008 | 0.001 | |||
Great lake | 0.008 | 0.004 | |||
U | −2.159 | 49 | 0.036 | ||
River | 0.022 | 0.006 | |||
Great lake | 0.029 | 0.012 | |||
Zna | 1.013 | 13.331 | 0.329 | ||
River | 3.867 | 6.939 | |||
Great lake | 1.978 | 1.271 |
SD, standard deviation.
aThe t and df were adjusted because variances were not equal.
One-way analysis of variance comparing regional groups on trace elements in the Tonle Sap Great Lake
Source . | . | df . | SS . | MS . | F . | p . |
---|---|---|---|---|---|---|
Ag | Between groups | 4 | 18.19 | 4.55 | 3.11 | 0.036 |
Within groups | 22 | 32.20 | 1.46 | |||
Total | 26 | 50.39 | ||||
Al | Between groups | 4 | 420,148.80 | 105,037.20 | 0.63 | 0.646 |
Within groups | 32 | 5,346,395.66 | 167,074.86 | |||
Total | 36 | 5,766,544.46 | ||||
As | Between groups | 4 | 0.85 | 0.21 | 3.73 | 0.013 |
Within groups | 32 | 1.83 | 0.06 | |||
Total | 36 | 2.68 | ||||
B | Between groups | 4 | 432.41 | 108.10 | 325.66 | <0.01 |
Within groups | 32 | 10.62 | 0.33 | |||
Total | 36 | 443.03 | ||||
Ba | Between groups | 4 | 630.15 | 157.54 | 12.83 | <0.01 |
Within groups | 32 | 392.85 | 12.28 | |||
Total | 36 | 1,023.00 | ||||
Co | Between groups | 4 | 0.52 | 0.13 | 2.59 | 0.055 |
Within groups | 32 | 1.60 | 0.05 | |||
Total | 36 | 2.12 | ||||
Cr | Between groups | 4 | 0.59 | 0.15 | 0.83 | 0.517 |
Within groups | 24 | 4.25 | 0.18 | |||
Total | 28 | 4.84 | ||||
Cu | Between groups | 4 | 11.44 | 2.86 | 33.80 | <0.01 |
Within groups | 32 | 2.71 | 0.08 | |||
Total | 36 | 14.14 | ||||
Fe | Between groups | 4 | 222,215.21 | 55,553.80 | 0.48 | 0.752 |
Within groups | 32 | 3,728,824.68 | 116,525.77 | |||
Total | 36 | 3,951,039.89 | ||||
Ga | Between groups | 4 | 17.56 | 4.39 | 7.78 | <0.01 |
Within groups | 32 | 18.06 | 0.56 | |||
Total | 36 | 35.62 | ||||
Mn | Between groups | 4 | 25,364.03 | 6,341.01 | 8.47 | <0.01 |
Within groups | 32 | 23,950.16 | 748.44 | |||
Total | 36 | 49,314.20 | ||||
Mo | Between groups | 4 | 0.01 | 0.00 | 1.20 | 0.329 |
Within groups | 32 | 0.05 | 0.00 | |||
Total | 36 | 0.05 | ||||
Ni | Between groups | 4 | 0.62 | 0.16 | 1.84 | 0.145 |
Within groups | 32 | 2.70 | 0.08 | |||
Total | 36 | 3.32 | ||||
Pb | Between groups | 4 | 0.11 | 0.03 | 0.64 | 0.638 |
Within groups | 32 | 1.43 | 0.04 | |||
Total | 36 | 1.54 | ||||
Se | Between groups | 4 | 0.02 | 0.01 | 20.73 | <0.01 |
Within groups | 32 | 0.01 | 0.00 | |||
Total | 36 | 0.03 | ||||
Tl | Between groups | 4 | 0.00 | 0.00 | 0.49 | 0.744 |
Within groups | 32 | 0.00 | 0.00 | |||
Total | 36 | 0.00 | ||||
U | Between groups | 4 | 0.00 | 0.00 | 0.86 | 0.496 |
Within groups | 32 | 0.00 | 0.00 | |||
Total | 36 | 0.01 | ||||
Zn | Between groups | 4 | 8.61 | 2.15 | 1.39 | 0.259 |
Within groups | 32 | 49.52 | 1.55 | |||
Total | 36 | 58.13 |
Source . | . | df . | SS . | MS . | F . | p . |
---|---|---|---|---|---|---|
Ag | Between groups | 4 | 18.19 | 4.55 | 3.11 | 0.036 |
Within groups | 22 | 32.20 | 1.46 | |||
Total | 26 | 50.39 | ||||
Al | Between groups | 4 | 420,148.80 | 105,037.20 | 0.63 | 0.646 |
Within groups | 32 | 5,346,395.66 | 167,074.86 | |||
Total | 36 | 5,766,544.46 | ||||
As | Between groups | 4 | 0.85 | 0.21 | 3.73 | 0.013 |
Within groups | 32 | 1.83 | 0.06 | |||
Total | 36 | 2.68 | ||||
B | Between groups | 4 | 432.41 | 108.10 | 325.66 | <0.01 |
Within groups | 32 | 10.62 | 0.33 | |||
Total | 36 | 443.03 | ||||
Ba | Between groups | 4 | 630.15 | 157.54 | 12.83 | <0.01 |
Within groups | 32 | 392.85 | 12.28 | |||
Total | 36 | 1,023.00 | ||||
Co | Between groups | 4 | 0.52 | 0.13 | 2.59 | 0.055 |
Within groups | 32 | 1.60 | 0.05 | |||
Total | 36 | 2.12 | ||||
Cr | Between groups | 4 | 0.59 | 0.15 | 0.83 | 0.517 |
Within groups | 24 | 4.25 | 0.18 | |||
Total | 28 | 4.84 | ||||
Cu | Between groups | 4 | 11.44 | 2.86 | 33.80 | <0.01 |
Within groups | 32 | 2.71 | 0.08 | |||
Total | 36 | 14.14 | ||||
Fe | Between groups | 4 | 222,215.21 | 55,553.80 | 0.48 | 0.752 |
Within groups | 32 | 3,728,824.68 | 116,525.77 | |||
Total | 36 | 3,951,039.89 | ||||
Ga | Between groups | 4 | 17.56 | 4.39 | 7.78 | <0.01 |
Within groups | 32 | 18.06 | 0.56 | |||
Total | 36 | 35.62 | ||||
Mn | Between groups | 4 | 25,364.03 | 6,341.01 | 8.47 | <0.01 |
Within groups | 32 | 23,950.16 | 748.44 | |||
Total | 36 | 49,314.20 | ||||
Mo | Between groups | 4 | 0.01 | 0.00 | 1.20 | 0.329 |
Within groups | 32 | 0.05 | 0.00 | |||
Total | 36 | 0.05 | ||||
Ni | Between groups | 4 | 0.62 | 0.16 | 1.84 | 0.145 |
Within groups | 32 | 2.70 | 0.08 | |||
Total | 36 | 3.32 | ||||
Pb | Between groups | 4 | 0.11 | 0.03 | 0.64 | 0.638 |
Within groups | 32 | 1.43 | 0.04 | |||
Total | 36 | 1.54 | ||||
Se | Between groups | 4 | 0.02 | 0.01 | 20.73 | <0.01 |
Within groups | 32 | 0.01 | 0.00 | |||
Total | 36 | 0.03 | ||||
Tl | Between groups | 4 | 0.00 | 0.00 | 0.49 | 0.744 |
Within groups | 32 | 0.00 | 0.00 | |||
Total | 36 | 0.00 | ||||
U | Between groups | 4 | 0.00 | 0.00 | 0.86 | 0.496 |
Within groups | 32 | 0.00 | 0.00 | |||
Total | 36 | 0.01 | ||||
Zn | Between groups | 4 | 8.61 | 2.15 | 1.39 | 0.259 |
Within groups | 32 | 49.52 | 1.55 | |||
Total | 36 | 58.13 |
df, degree of freedom; SS, sum of squares; MS, mean square.
Comparisons of trace elements (μg L−1) in the Tonle Sap Great Lake and lakes in other countries
. | Cambodia Tonle Sap Great Lake (present study) . | Chinaa . | Kenyab . | Pakistanc . | New Zealandd . | South Americae . | USAf . | ||||
---|---|---|---|---|---|---|---|---|---|---|---|
Elements . | TSB . | TSS . | TSP . | TSC . | TST . | Taihu Lake . | Victoria . | Rawal Lake . | Lake Hauroko . | Titicaca . | Hough Park Lake . |
Ag | 0.21 | 1.95 | 0.23 | 0.15 | 0.30 | – | – | – | – | – | – |
Al | 27.72 | 261.16 | 19.90 | 12.04 | 18.16 | – | – | – | – | – | 436.00 |
As | 1.14 | 1.28 | 1.15 | 0.77 | 1.33 | 1.86 | – | – | – | – | – |
B | 13.32 | 13.18 | 6.18 | 6.33 | 7.31 | – | – | – | – | – | – |
Ba | 16.44 | 17.53 | 22.58 | 24.82 | 29.80 | – | – | – | – | – | 43.00 |
Cd | N/A | N/A | N/A | N/A | N/A | 0.06 | 0.12 | 6.00 | 0.0013 | 0.06 | – |
Co | 0.048 | 0.143 | 0.050 | 0.045 | 0.483 | – | 0.05 | 11.00 | 0.005 | 0.25 | – |
Cr | 0.109 | 0.383 | 0.032 | 0.130 | 0.057 | 0.99 | 0.13 | 9.00 | – | – | 1.00 |
Cu | 1.57 | 1.98 | 0.76 | 0.80 | 0.45 | 5.81 | 2.20 | 10.00 | 0.235 | 2.45 | – |
Fe | 39.00 | 224.51 | 87.42 | 28.73 | 165.50 | – | – | 93.00 | 0.005 | 111.6 | 298.00 |
Ga | 3.26 | 3.57 | 4.28 | 4.78 | 5.53 | – | – | – | – | – | – |
Mn | 0.71 | 4.92 | 10.12 | 9.85 | 100.72 | – | – | 4.00 | 0.080 | – | 93.00 |
Mo | 0.210 | 0.210 | 0.206 | 0.212 | 0.160 | – | – | – | – | – | – |
Ni | 0.33 | 0.57 | 0.33 | 0.16 | 0.46 | 5.34 | – | – | 0.106 | – | 1.00 |
Pb | 0.109 | 0.220 | 0.095 | 0.075 | 0.095 | 2.74 | – | 162.00 | 0.002 | 3.07 | 0.40 |
Se | 0.100 | 0.101 | 0.059 | 0.046 | 0.043 | – | – | – | – | – | – |
Tl | 0.008 | 0.009 | 0.009 | 0.007 | 0.006 | – | – | – | – | – | – |
U | 0.033 | 0.027 | 0.029 | 0.033 | 0.019 | – | – | – | – | – | – |
Zn | 1.26 | 2.46 | 2.12 | 1.83 | 2.48 | 15.86 | 8.3 | 14.00 | 0.054 | 23.67 | 3.00 |
. | Cambodia Tonle Sap Great Lake (present study) . | Chinaa . | Kenyab . | Pakistanc . | New Zealandd . | South Americae . | USAf . | ||||
---|---|---|---|---|---|---|---|---|---|---|---|
Elements . | TSB . | TSS . | TSP . | TSC . | TST . | Taihu Lake . | Victoria . | Rawal Lake . | Lake Hauroko . | Titicaca . | Hough Park Lake . |
Ag | 0.21 | 1.95 | 0.23 | 0.15 | 0.30 | – | – | – | – | – | – |
Al | 27.72 | 261.16 | 19.90 | 12.04 | 18.16 | – | – | – | – | – | 436.00 |
As | 1.14 | 1.28 | 1.15 | 0.77 | 1.33 | 1.86 | – | – | – | – | – |
B | 13.32 | 13.18 | 6.18 | 6.33 | 7.31 | – | – | – | – | – | – |
Ba | 16.44 | 17.53 | 22.58 | 24.82 | 29.80 | – | – | – | – | – | 43.00 |
Cd | N/A | N/A | N/A | N/A | N/A | 0.06 | 0.12 | 6.00 | 0.0013 | 0.06 | – |
Co | 0.048 | 0.143 | 0.050 | 0.045 | 0.483 | – | 0.05 | 11.00 | 0.005 | 0.25 | – |
Cr | 0.109 | 0.383 | 0.032 | 0.130 | 0.057 | 0.99 | 0.13 | 9.00 | – | – | 1.00 |
Cu | 1.57 | 1.98 | 0.76 | 0.80 | 0.45 | 5.81 | 2.20 | 10.00 | 0.235 | 2.45 | – |
Fe | 39.00 | 224.51 | 87.42 | 28.73 | 165.50 | – | – | 93.00 | 0.005 | 111.6 | 298.00 |
Ga | 3.26 | 3.57 | 4.28 | 4.78 | 5.53 | – | – | – | – | – | – |
Mn | 0.71 | 4.92 | 10.12 | 9.85 | 100.72 | – | – | 4.00 | 0.080 | – | 93.00 |
Mo | 0.210 | 0.210 | 0.206 | 0.212 | 0.160 | – | – | – | – | – | – |
Ni | 0.33 | 0.57 | 0.33 | 0.16 | 0.46 | 5.34 | – | – | 0.106 | – | 1.00 |
Pb | 0.109 | 0.220 | 0.095 | 0.075 | 0.095 | 2.74 | – | 162.00 | 0.002 | 3.07 | 0.40 |
Se | 0.100 | 0.101 | 0.059 | 0.046 | 0.043 | – | – | – | – | – | – |
Tl | 0.008 | 0.009 | 0.009 | 0.007 | 0.006 | – | – | – | – | – | – |
U | 0.033 | 0.027 | 0.029 | 0.033 | 0.019 | – | – | – | – | – | – |
Zn | 1.26 | 2.46 | 2.12 | 1.83 | 2.48 | 15.86 | 8.3 | 14.00 | 0.054 | 23.67 | 3.00 |
TSB, Tonle Sap Battambang; TST, Tonle Sap Siem Reap; TSP, Tonle Sap Pursat; TSC, Tonle Sap Kampong Chhnang; TST, Tonle Sap Kampong Thom.
Assessment of health risks from drinking lake and river water
The average daily doses (ADDs) of single trace elements are provided in Table 5. The HQ of a single trace element and the hazard index (HI) of multiple trace elements are presented in Table 6. In total, 16 trace elements were included in the health risk assessment. Cadmium was excluded because it was not detected in any river and lake water samples. Gallium and lead were excluded because their oral reference doses (RfDs) were not available at the USEPA. Calculations indicated that male and female Cambodian residents ingested less amount of trace elements in water from the Tonle Sap River and the Tonle Sap Great Lake than those in Pakistan (Iqbal et al. 2013) and China (Wu et al. 2009; Li & Zhang 2010). Moreover, risk calculation indicated that all HQs of each single trace element and the HI of the multiple trace elements were less than one, indicating male and female Cambodian residents were at minimal risk of single and multiple trace elements through consumption of the Tonle Sap Great Lake and River water. Health risk assessment of trace metals in freshwater Rawal Lake, Pakistan revealed that Co and Pb were the major pollutants during summer and Cd, Co, Cr and Pb were the major pollutants during winter, which could pose adverse health effects to the local consumers through the water drinking pathway (Iqbal et al. 2013). Recently, a health risk assessment of trace elements in the upper Han River, China indicated that As, Pb, Sb, Se and V were the largest contributor to chronic risk in the dry season while As, Co, Pb, Sb and V in the rainy season (Li & Zhang 2010). Concurrently, a health risk assessment of trace metal in surface water from the Yangtze River in Nanjing section, China suggested trace metals could pose a minimal hazard to local residents (Wu et al. 2009). It is apparent that the Tonle Sap River and the Tonle Sap Great Lake water were substantially safe in trace elements and could be used as drinking water sources, considering the treatments of microbial contaminants and organic pollutants as well as emerging environmental pharmaceuticals. However, Cambodian local residents were at relatively high potential health risks of As, Tl, Ba, Co, Mn and Cr when compared to other trace elements (Table 6). The management and control of the contamination sources should be taken into account. In fact, if industrial and municipal sewages are well managed and controlled prior to discharges to the Tonle Sap River, it might reduce the potential health risks to the consumers who rely on the Tonle Sap Great Lake resources such as water and fishery products. It might also reduce the ecological risks to the aquatic plants and animals in the Great Lake system. Nevertheless, we have not investigated seasonal changes which are believed to influence the concentrations of these trace elements and the water quality of the Great Lake and its tributary due to budget and time constraints. These limitations allowed us to assess the health risks of consumers only in the rainy season (May to November). However, the authors feel that it is substantially informative because a few people would consume lake and river water in the dry season (December to April) due to a long-distance carrier. Our previous study showed that groundwater in the Mekong River basin is the main source of drinking although many people live alongside surface water (Phan et al. 2010). Many people switched from the consumption of surface water to groundwater owing to their concerns about microbial contaminations (Phan et al. 2010). Of course, surface water is consumed during the raising stage of the Mekong River water which results in an overflow and flooding.
Summary of average daily intake (×10−2 μg kg−1 d−1) of trace elements of Cambodian residents through drinking water from the Tonle Sap River and the Tonle Sap Great Lake
. | Tonle Sap River . | Tonle Sap Great Lake . | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
. | Female . | . | Male . | Female . | . | Male . | ||||||||
Elements . | Mean . | Median . | SD . | . | Mean . | Median . | SD . | Mean . | Median . | SD . | . | Mean . | Median . | SD . |
Ag | 1.29 | 1.39 | 0.46 | 1.52 | 1.64 | 0.55 | 1.26 | 0.36 | 2.23 | 1.49 | 0.42 | 2.62 | ||
Al | 18.03 | 9.48 | 20.93 | 21.20 | 11.15 | 24.62 | 138.08 | 26.56 | 640.87 | 162.39 | 31.24 | 753.72 | ||
As | 1.10 | 1.02 | 0.29 | 1.29 | 1.20 | 0.34 | 1.85 | 1.88 | 0.44 | 2.18 | 2.21 | 0.51 | ||
B | 8.80 | 8.60 | 0.78 | 10.35 | 10.11 | 0.92 | 16.18 | 20.05 | 5.62 | 19.03 | 23.58 | 6.61 | ||
Ba | 31.17 | 30.76 | 1.89 | 36.66 | 36.18 | 2.22 | 32.64 | 30.01 | 8.54 | 38.39 | 35.29 | 10.04 | ||
Co | 0.10 | 0.09 | 0.02 | 0.11 | 0.10 | 0.02 | 0.18 | 0.08 | 0.39 | 0.21 | 0.09 | 0.46 | ||
Cr | 0.14 | 0.09 | 0.12 | 0.16 | 0.10 | 0.15 | 0.31 | 0.18 | 0.67 | 0.36 | 0.21 | 0.78 | ||
Cu | 1.30 | 1.22 | 0.27 | 1.53 | 1.44 | 0.32 | 2.06 | 2.23 | 1.00 | 2.42 | 2.62 | 1.18 | ||
Fe | 34.11 | 8.39 | 72.09 | 40.11 | 9.87 | 84.79 | 178.33 | 49.35 | 530.48 | 209.74 | 58.04 | 623.89 | ||
Mn | 14.76 | 12.99 | 5.61 | 17.35 | 15.27 | 6.60 | 21.60 | 3.31 | 59.26 | 25.40 | 3.90 | 69.70 | ||
Mo | 0.23 | 0.21 | 0.06 | 0.27 | 0.25 | 0.07 | 0.33 | 0.33 | 0.06 | 0.39 | 0.39 | 0.07 | ||
Ni | 0.30 | 0.25 | 0.11 | 0.35 | 0.29 | 0.13 | 0.62 | 0.53 | 0.49 | 0.72 | 0.62 | 0.57 | ||
Se | 0.09 | 0.09 | 0.02 | 0.11 | 0.11 | 0.02 | 0.13 | 0.12 | 0.05 | 0.15 | 0.15 | 0.05 | ||
Tl | 0.01 | 0.01 | 0.00 | 0.01 | 0.01 | 0.00 | 0.01 | 0.01 | 0.01 | 0.02 | 0.01 | 0.01 | ||
U | 0.03 | 0.03 | 0.01 | 0.04 | 0.04 | 0.01 | 0.05 | 0.05 | 0.02 | 0.05 | 0.06 | 0.02 | ||
Zn | 6.19 | 2.41 | 11.11 | 7.28 | 2.83 | 13.07 | 3.17 | 2.59 | 2.03 | 3.72 | 3.05 | 2.39 |
. | Tonle Sap River . | Tonle Sap Great Lake . | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
. | Female . | . | Male . | Female . | . | Male . | ||||||||
Elements . | Mean . | Median . | SD . | . | Mean . | Median . | SD . | Mean . | Median . | SD . | . | Mean . | Median . | SD . |
Ag | 1.29 | 1.39 | 0.46 | 1.52 | 1.64 | 0.55 | 1.26 | 0.36 | 2.23 | 1.49 | 0.42 | 2.62 | ||
Al | 18.03 | 9.48 | 20.93 | 21.20 | 11.15 | 24.62 | 138.08 | 26.56 | 640.87 | 162.39 | 31.24 | 753.72 | ||
As | 1.10 | 1.02 | 0.29 | 1.29 | 1.20 | 0.34 | 1.85 | 1.88 | 0.44 | 2.18 | 2.21 | 0.51 | ||
B | 8.80 | 8.60 | 0.78 | 10.35 | 10.11 | 0.92 | 16.18 | 20.05 | 5.62 | 19.03 | 23.58 | 6.61 | ||
Ba | 31.17 | 30.76 | 1.89 | 36.66 | 36.18 | 2.22 | 32.64 | 30.01 | 8.54 | 38.39 | 35.29 | 10.04 | ||
Co | 0.10 | 0.09 | 0.02 | 0.11 | 0.10 | 0.02 | 0.18 | 0.08 | 0.39 | 0.21 | 0.09 | 0.46 | ||
Cr | 0.14 | 0.09 | 0.12 | 0.16 | 0.10 | 0.15 | 0.31 | 0.18 | 0.67 | 0.36 | 0.21 | 0.78 | ||
Cu | 1.30 | 1.22 | 0.27 | 1.53 | 1.44 | 0.32 | 2.06 | 2.23 | 1.00 | 2.42 | 2.62 | 1.18 | ||
Fe | 34.11 | 8.39 | 72.09 | 40.11 | 9.87 | 84.79 | 178.33 | 49.35 | 530.48 | 209.74 | 58.04 | 623.89 | ||
Mn | 14.76 | 12.99 | 5.61 | 17.35 | 15.27 | 6.60 | 21.60 | 3.31 | 59.26 | 25.40 | 3.90 | 69.70 | ||
Mo | 0.23 | 0.21 | 0.06 | 0.27 | 0.25 | 0.07 | 0.33 | 0.33 | 0.06 | 0.39 | 0.39 | 0.07 | ||
Ni | 0.30 | 0.25 | 0.11 | 0.35 | 0.29 | 0.13 | 0.62 | 0.53 | 0.49 | 0.72 | 0.62 | 0.57 | ||
Se | 0.09 | 0.09 | 0.02 | 0.11 | 0.11 | 0.02 | 0.13 | 0.12 | 0.05 | 0.15 | 0.15 | 0.05 | ||
Tl | 0.01 | 0.01 | 0.00 | 0.01 | 0.01 | 0.00 | 0.01 | 0.01 | 0.01 | 0.02 | 0.01 | 0.01 | ||
U | 0.03 | 0.03 | 0.01 | 0.04 | 0.04 | 0.01 | 0.05 | 0.05 | 0.02 | 0.05 | 0.06 | 0.02 | ||
Zn | 6.19 | 2.41 | 11.11 | 7.28 | 2.83 | 13.07 | 3.17 | 2.59 | 2.03 | 3.72 | 3.05 | 2.39 |
SD, standard deviation.
Summary of RfD (μg kg−1 d−1) and non-carcinogenic risks of single (HQ ×10−2) and mixed (HI ×10−2) elements of Cambodian residents through drinking water from the Tonle Sap River and the Tonle Sap Great Lake
. | . | Tonle Sap River . | . | Tonle Sap Great Lake . | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
. | . | Female . | . | Male . | . | Female . | . | Male . | ||||||||
Elements . | RfD . | Mean . | Median . | SD . | . | Mean . | Median . | SD . | . | Mean . | Median . | SD . | . | Mean . | Median . | SD . |
Ag | 5 | 0.26 | 0.28 | 0.09 | 0.30 | 0.33 | 0.11 | 0.25 | 0.07 | 0.45 | 0.30 | 0.08 | 0.52 | |||
Al | 1000 | 0.02 | 0.01 | 0.02 | 0.02 | 0.01 | 0.02 | 0.14 | 0.03 | 0.64 | 0.16 | 0.03 | 0.75 | |||
As | 0.3 | 3.66 | 3.40 | 0.97 | 4.31 | 4.00 | 1.14 | 6.17 | 6.25 | 1.46 | 7.25 | 7.35 | 1.71 | |||
B | 200 | 0.04 | 0.04 | 0.00 | 0.05 | 0.05 | 0.00 | 0.08 | 0.10 | 0.03 | 0.10 | 0.12 | 0.03 | |||
Ba | 200 | 0.16 | 0.15 | 0.01 | 0.18 | 0.18 | 0.01 | 0.16 | 0.15 | 0.04 | 0.19 | 0.18 | 0.05 | |||
Co | 0.3 | 0.32 | 0.30 | 0.07 | 0.38 | 0.35 | 0.08 | 0.58 | 0.27 | 1.29 | 0.69 | 0.31 | 1.52 | |||
Cr | 3 | 0.05 | 0.03 | 0.04 | 0.05 | 0.03 | 0.05 | 0.10 | 0.06 | 0.22 | 0.12 | 0.07 | 0.26 | |||
Cu | 40 | 0.03 | 0.03 | 0.01 | 0.04 | 0.04 | 0.01 | 0.05 | 0.06 | 0.03 | 0.06 | 0.07 | 0.03 | |||
Fe | 700 | 0.05 | 0.01 | 0.10 | 0.06 | 0.01 | 0.12 | 0.25 | 0.07 | 0.76 | 0.30 | 0.08 | 0.89 | |||
Mn | 140 | 0.11 | 0.09 | 0.04 | 0.12 | 0.11 | 0.05 | 0.15 | 0.02 | 0.42 | 0.18 | 0.03 | 0.50 | |||
Mo | 5 | 0.05 | 0.04 | 0.01 | 0.05 | 0.05 | 0.01 | 0.07 | 0.07 | 0.01 | 0.08 | 0.08 | 0.01 | |||
Ni | 20 | 0.01 | 0.01 | 0.01 | 0.02 | 0.01 | 0.01 | 0.03 | 0.03 | 0.02 | 0.04 | 0.03 | 0.03 | |||
Se | 5 | 0.02 | 0.02 | 0.00 | 0.02 | 0.02 | 0.00 | 0.03 | 0.02 | 0.01 | 0.03 | 0.03 | 0.01 | |||
Tl | 0.01 | 1.23 | 1.22 | 0.19 | 1.45 | 1.43 | 0.22 | 1.32 | 1.22 | 0.60 | 1.56 | 1.43 | 0.70 | |||
U | 3 | 0.01 | 0.01 | 0.00 | 0.01 | 0.01 | 0.00 | 0.02 | 0.02 | 0.01 | 0.02 | 0.02 | 0.01 | |||
Zn | 300 | 0.02 | 0.01 | 0.04 | 0.02 | 0.01 | 0.04 | 0.01 | 0.01 | 0.01 | 0.01 | 0.01 | 0.01 | |||
HI | 6.03 | 5.65 | 1.61 | 7.09 | 6.65 | 1.89 | 9.42 | 8.44 | 5.99 | 11.08 | 9.92 | 7.05 |
. | . | Tonle Sap River . | . | Tonle Sap Great Lake . | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
. | . | Female . | . | Male . | . | Female . | . | Male . | ||||||||
Elements . | RfD . | Mean . | Median . | SD . | . | Mean . | Median . | SD . | . | Mean . | Median . | SD . | . | Mean . | Median . | SD . |
Ag | 5 | 0.26 | 0.28 | 0.09 | 0.30 | 0.33 | 0.11 | 0.25 | 0.07 | 0.45 | 0.30 | 0.08 | 0.52 | |||
Al | 1000 | 0.02 | 0.01 | 0.02 | 0.02 | 0.01 | 0.02 | 0.14 | 0.03 | 0.64 | 0.16 | 0.03 | 0.75 | |||
As | 0.3 | 3.66 | 3.40 | 0.97 | 4.31 | 4.00 | 1.14 | 6.17 | 6.25 | 1.46 | 7.25 | 7.35 | 1.71 | |||
B | 200 | 0.04 | 0.04 | 0.00 | 0.05 | 0.05 | 0.00 | 0.08 | 0.10 | 0.03 | 0.10 | 0.12 | 0.03 | |||
Ba | 200 | 0.16 | 0.15 | 0.01 | 0.18 | 0.18 | 0.01 | 0.16 | 0.15 | 0.04 | 0.19 | 0.18 | 0.05 | |||
Co | 0.3 | 0.32 | 0.30 | 0.07 | 0.38 | 0.35 | 0.08 | 0.58 | 0.27 | 1.29 | 0.69 | 0.31 | 1.52 | |||
Cr | 3 | 0.05 | 0.03 | 0.04 | 0.05 | 0.03 | 0.05 | 0.10 | 0.06 | 0.22 | 0.12 | 0.07 | 0.26 | |||
Cu | 40 | 0.03 | 0.03 | 0.01 | 0.04 | 0.04 | 0.01 | 0.05 | 0.06 | 0.03 | 0.06 | 0.07 | 0.03 | |||
Fe | 700 | 0.05 | 0.01 | 0.10 | 0.06 | 0.01 | 0.12 | 0.25 | 0.07 | 0.76 | 0.30 | 0.08 | 0.89 | |||
Mn | 140 | 0.11 | 0.09 | 0.04 | 0.12 | 0.11 | 0.05 | 0.15 | 0.02 | 0.42 | 0.18 | 0.03 | 0.50 | |||
Mo | 5 | 0.05 | 0.04 | 0.01 | 0.05 | 0.05 | 0.01 | 0.07 | 0.07 | 0.01 | 0.08 | 0.08 | 0.01 | |||
Ni | 20 | 0.01 | 0.01 | 0.01 | 0.02 | 0.01 | 0.01 | 0.03 | 0.03 | 0.02 | 0.04 | 0.03 | 0.03 | |||
Se | 5 | 0.02 | 0.02 | 0.00 | 0.02 | 0.02 | 0.00 | 0.03 | 0.02 | 0.01 | 0.03 | 0.03 | 0.01 | |||
Tl | 0.01 | 1.23 | 1.22 | 0.19 | 1.45 | 1.43 | 0.22 | 1.32 | 1.22 | 0.60 | 1.56 | 1.43 | 0.70 | |||
U | 3 | 0.01 | 0.01 | 0.00 | 0.01 | 0.01 | 0.00 | 0.02 | 0.02 | 0.01 | 0.02 | 0.02 | 0.01 | |||
Zn | 300 | 0.02 | 0.01 | 0.04 | 0.02 | 0.01 | 0.04 | 0.01 | 0.01 | 0.01 | 0.01 | 0.01 | 0.01 | |||
HI | 6.03 | 5.65 | 1.61 | 7.09 | 6.65 | 1.89 | 9.42 | 8.44 | 5.99 | 11.08 | 9.92 | 7.05 |
RfD, Reference Dose; SD, standard deviation
CONCLUSIONS
The total number of 19 trace elements (Ag, Al, As, B, Ba, Cd, Co, Cr, Cu, Fe, Ga, Mn, Mo, Ni, Pb, Se, Tl, U and Zn) in the Tonle Sap Great Lake and its tributary were determined. Cadmium was not detected in any river and lake waters. Comparisons did not show significant differences in Ag, Al, Ba, Co, Cr, Fe, Ga, Mn, Pb, Tl and Zn concentrations in the Great Lake and its tributary. However, As, B, Cu, Mo, Ni, Se and U concentrations in the Great Lake were significantly higher than those in the river. Concurrently, there were significant differences in Ag, As, B, Ba, Cu, Ga, Mn and Se among the five surrounding provinces of the Great Lake. Nevertheless, Al, Co, Cr, Fe, Mo, Ni, Pb, Tl, U and Zn were not significantly different among the five provinces. Although a number of river and lake water samples had certain trace elements greater than the average levels in the world natural rivers, only Al, Fe and Mn in lake water exceeded the regulation limits. When compared to lakes in other countries, the Tonle Sap Great Lake was less polluted than the others. Moreover, health risk assessment indicated that male and female Cambodian residents are at minimal risk of non-carcinogenic effects of single and mixed trace elements through lake and river water consumption. However, more attention should be paid to As, Tl, Co, Ba, Mn and Cr because they might pose high potential health risks to local residents. Therefore, regular monitoring and further investigations of temporal and spatial distribution are warranted to advance understanding of the pollution trends and toxic behavior of these trace elements in the Tonle Sap Great Lake system.
ACKNOWLEDGEMENTS
The authors would like to thank Mr Sundeth Say and Mr Rithy Aem for their invaluable field assistance.
FUNDING
This work was supported by GIST Research Institute (GRI) grant funded by the Gwangju Institute of Science and Technology (GIST) in 2023.
CONSENT TO PUBLISH
All authors read and approved the content of the final manuscript.
DATA AVAILABILITY STATEMENT
All relevant data are included in the paper or its Supplementary Information.
CONFLICT OF INTEREST
The authors declare there is no conflict.