Environ Sci Pollut Res DOI 10.1007/s11356-014-2995-4
RESEARCH ARTICLE
Heavy metals and polycyclic aromatic hydrocarbons in sediments from the Shenzhen River, South China Guoping Deng & Wenqing Yang & Guanye Zhou & Yun Li & Shili Liu
Received: 15 August 2013 / Accepted: 30 April 2014 # Springer-Verlag Berlin Heidelberg 2014
Abstract With the analysis of eight heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) and sixteen polycyclic aromatic hydrocarbons (PAHs) in sediments from the Shenzhen River, South China, the ecological risks associated were evaluated using Hakanson’s method (for the metals) and the Effect Range Low/Effect Range Median (ERL/ERM) method (for the PAHs). The result shows concentrations of heavy metal in the order Zn>Cu>Cr>Ni>Pb>As>Cd>Hg, and among which the Zn, Cu, Ni, and Pb are exceeding the maximum contaminant level for sediments while those of PAHs are far below. The potential ecological risk index value for the heavy metals in the sediment samples was 261.90, which is in the moderate risk category. Total PAH concentrations in the sediments ranged from 1,028 to 1,120 ng/g, which are all far lower than the sediment guideline concentration of 4,022 ng/g, indicating that the risks of biological impacts caused by PAHs in Shenzhen River sediments are, therefore, relatively low. Besides, the fluorene concentration was above the ERL, and would potentially cause negative biological effects in the Shenzhen River. Heavy metals risks are suggested among the most important concerns that the environmental recover measures pay attention to. Keywords Heavy metal . PAH . Ecological risk . Sediment . Shenzhen River
Introduction Heavy metals and polycyclic aromatic hydrocarbons (PAHs) pollution in sediments has become an important environmental Responsible editor: Roland Kallenborn G. Deng (*) : W. Yang : G. Zhou : Y. Li : S. Liu Research and Development Center, Dongjiang Environmental Company Limited, Shenzhen 518104, China e-mail: [email protected]
issue in many countries (Heikens et al. 2001; Yang et al. 2009). During the past decades of fast growth, large quantity of industrial effluent entered the Shenzhen River. Heavy metals emitted into the aquatic environment are usually first dissolved in the water, then they adsorb to particles through relatively weak physical and chemical bonds, the particles finally sink and accumulate in the water sediments (Pempkowiase et al. 1999). The distribution of heavy metals in the bottom sediment is affected by the mineralogical and chemical composition of the suspended material, anthropogenic influences, and situational processes such as deposition, sorption, and enrichment in organisms (Jain et al. 2005). Most studies of contaminants in sediments have been focused on heavy metals, and only a few studies have focused on PAHs, which are toxic to aquatic organisms, and some of which are carcinogenic to humans (Bihari et al. 2007). Sediments are important reservoirs for many persistent organic pollutants (POPs), including PAHs, and are one of the media through which POPs enter aquaculture and wildlife food chains (Baumard et al. 1998; Hu et al. 2011). The Shenzhen River serves as the natural administrative border between Hong Kong and Shenzhen City, and locates in one of the most developed regions in China. The river is suffering from deteriorating water and sediment quality because of the increasing amounts of pollution emitted into it, as the tributaries of fast growing city of Shenzhen. Till the time of writing, the source-root-up project against pollution to the Shenzhen River Region has achieved its accomplishment, the government is moving onto the evaluation sediments contamination and corresponding recovery measures. According to recent studies, As, Cd, Cr, Cu, Hg, Ni, Pb, Zn, and PAHs often accumulate in sediments because of the effects of industrial, municipal, and mining activities (Heath et al. 2010; Milačič et al. 2010; Sharmin et al. 2009; Varol 2011). Investigation of heavy metals and PAHs in sediments can provide useful information to further our understanding of their environment fate and behavior. The normal evaluation measures are on the
Environ Sci Pollut Res
pollutant values of sample sediment in comparison to the background values and/or the authoritative standard value. However, it is now widely accepted that the roles of aquatic sediments as sinks and sources of pollutants, especially heavy metals, cannot be fully assessed by measuring the total heavy metal concentrations (Jain et al. 2004). Researchers adopt the Hakanson’s method and Effect Range Low/Effect Range Median (ERL/ERM) method in the evaluation of ecological risks of heavy metals and PAHs in the water sediments (Fu et al. 2009; Hartmann et al. 2004). The objective of the study presented here was to evaluate the quality of the sediments in the Shenzhen River, and to provide valuable reference in the planning of remediation actions. The concentrations of heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) and sixteen PAH compounds were analyzed in sediment samples, and an ecological risk assessment was performed for each chemical.
Materials and methods Site description and sediment sampling The locations of the sampling sites are shown in Fig. 1. Sample S1 was collected at the Luohu check port in the
Fig. 1 Map of the sediment sampling sites in the Shenzhen River
Shenzhen River, upstream of Shenzhen, at 114.1140° E 22.5302° N. Sample S2 was collected near the Shangbu loading area, at 114.0563° E 22.5042° N, where the sediment is alternately affected by freshwater and seawater with the changing tide. The Shenzhen and Hong Kong governments had accomplished three phases of remediation work including widening the river channel, cleaning sediment, and clearing pollution source. This study is part of the basic investigations for the fourth phase. The sediment from those spots has the best representativeness, which are the same spot of previous there phase of recover measures, and the hydrologic monitoring section of local authoritative. Sediment samples (500 L, from 0–0.5 m deep) were collected from the river bed using a clamshell sediment collector on 7 August 2012, and were stored in PTFE bags, frozen to and stored at−20 °C, until they were analyzed. The sampling procedures are in conformance with the Chinese national standard GB 17378.3-2007 (General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China 2007). Sample analysis The sediment samples analysis were carried out by a third part with China Metrology Certification, SGSC S T C S t a n d a r d s Te c h n i c a l S e r v i c e s C o . , L t d (Guangzhou, China). The sample for heavy metal concentration values is prepared according to the US Environmental Protection Agency (US EPA) Method 3050B (US EPA 1996): dispelling with HNO3-H2O2, and an amount of solid sediment 10 g was analyzed; the sample for PAHs was processed in the supersonic wave dispelling US EPA method 3550B (US EPA 1998). Cd, Cr, Cu, Ni, Pb, and Zn were determined by atomic absorption spectrometry, and As and Hg were determined by atomic fluorescence spectrometry, after acid digestion, in the appropriate China national standard methods GB/T 17138–1997, GB/T 17139–1997, GB/T 17141–2007, and HJ 491–2009 (Ministry of Environmental Protection, the People’s Republic of China 1997a; b; c; 2009) and GB/T 22105.1-2008 and 22105.2-2008 (General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China 2008a; b). The PAHs were determined by gas chromatography/mass spectrometry (GC/ MS), following China national standard method GB 5085.3-2007 (Ministry of Environmental Protection, the People’s Republic of China 2007) for semivolatile organic compounds. All data were subjected to strict quality control procedures, including analysis of method blanks, spiked blanks, and matrix spikes.
Environ Sci Pollut Res Table 1 Heavy metal concentration values (mg/kg, dry weight) in the sediment from different estuaries and comparison with quality standards
(1) (2) (3) (4) (5) (6) (7) (8) (8) (9)
Cd
Cr
Cu
Ni
Pb
Zn
Hg
As
0.81 0.88 1.5 1.5/4 1 0.1–0.5 0.08–0.64 6–14 3–10 –
129 139 80 80/160 52.3 26–54 55–802
162 194 100 65/110 18.7 24–86 4–23 28–104 20–57 110.55
107 133 – 40/40 15.9 15–35 16–45 28–40 21–39 91.12
102 82 130 75/110 30.2 35–70 5.9–21.3 281–406 125–334 11.67
659 723 350 200/270 124 88–285 39–188 105–792 91–650 87.94
0.20 0.30 0.5 0.5/1 0.13 0.09–0.18 –
11.8 12.2 65 12/42 7.24 16–20 –
– –
– –
48–91 254.52
(1) Present study S1 average concentration, (2) present study S2 average concentration, (3) marine sediment quality. China (General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China 2008a, b), (4) Technical Circular NO.34/2002. Hong Kong (Environment and Works Bureau 2002), (5) ecological screening values (U.S. EOP 1999), (6) Deep Bay. China (Environmental Protection Department 2000), (7) coastal sediments from Baja California (Mexico) and California (USA) (Villaescusa-Celaya et al. 2000), (8) Kaoping River, Tungkang River, and Lingbeng River in southwestern Taiwan (Chung et al. 2011), (9) Kabini River in Karnataka, India (Taghinia Hejabi et al. 2011)
Results and discussion Heavy metal concentrations The sediment samples from each site were divided into three subsamples for analysis, and the average concentration of the eight heavy metals in each of the samples are presented in Table 1. It can be seen that the values were fairly similar in the two samples; the highest heavy metal concentration was for Zn, at a mean of 659–723 mg/kg, Hg was found at the lowest concentrations. The values in comparison with the similar studies and corresponding quality standards indicated that Cr, Cu, Ni, Pb, and Zn in the present study exceeded the standard values of GB 18668–2002 (Ministry of Environmental Protection, the People's Republic of China 2002), Lower/Upper Chemical Exceedance Level (Hong Kong), and Ecological Screening Values (USA), which means the region’s potential ecological risk. All of the heavy metals density values were found higher than those of Shenzhen Deep Bay (China) and California coastal, investigated in 2000 and 2011, respectively. Meanwhile, Cu, Ni, Pb, and Zn values were higher than in rivers neighboring Dapeng Bay (Taiwan)
Table 2 The relationships between the integrated pollution index and the pollution degrees
and Kabini River in Karnataka (India). The results are obvious: sediments in Shenzhen Rive have higher density values than the level of the local background and other similar rivers in the world, which is suggested to have great attention. Evaluation of heavy metal pollution in sediments Hakanson’s ecological risk assessment method (Lars 1980) was adopted in evaluation of the potential ecological risks associated with the metal contaminant concentrations found in the sediment samples. The potential ecological risk index method, which uses the characteristics of the heavy metal and its environmental behavior, is an approach for evaluating heavy metal contamination from the perspective of sedimentology. It not only considers heavy metal concentrations in the soil, but also includes ecological toxicological effects, and is used to evaluate pollution in comparable and equivalentproperty-index grading methods. The potential ecological risk index is related to the individual pollution coefficient, the heavy metal toxic response coefficient, and the individual potential ecological risk coefficient, and it is calculated using the formulae:
C if
Pollution degree
E if
RI
Potential ecological risk degree
C if
RESEARCH ARTICLE
Heavy metals and polycyclic aromatic hydrocarbons in sediments from the Shenzhen River, South China Guoping Deng & Wenqing Yang & Guanye Zhou & Yun Li & Shili Liu
Received: 15 August 2013 / Accepted: 30 April 2014 # Springer-Verlag Berlin Heidelberg 2014
Abstract With the analysis of eight heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) and sixteen polycyclic aromatic hydrocarbons (PAHs) in sediments from the Shenzhen River, South China, the ecological risks associated were evaluated using Hakanson’s method (for the metals) and the Effect Range Low/Effect Range Median (ERL/ERM) method (for the PAHs). The result shows concentrations of heavy metal in the order Zn>Cu>Cr>Ni>Pb>As>Cd>Hg, and among which the Zn, Cu, Ni, and Pb are exceeding the maximum contaminant level for sediments while those of PAHs are far below. The potential ecological risk index value for the heavy metals in the sediment samples was 261.90, which is in the moderate risk category. Total PAH concentrations in the sediments ranged from 1,028 to 1,120 ng/g, which are all far lower than the sediment guideline concentration of 4,022 ng/g, indicating that the risks of biological impacts caused by PAHs in Shenzhen River sediments are, therefore, relatively low. Besides, the fluorene concentration was above the ERL, and would potentially cause negative biological effects in the Shenzhen River. Heavy metals risks are suggested among the most important concerns that the environmental recover measures pay attention to. Keywords Heavy metal . PAH . Ecological risk . Sediment . Shenzhen River
Introduction Heavy metals and polycyclic aromatic hydrocarbons (PAHs) pollution in sediments has become an important environmental Responsible editor: Roland Kallenborn G. Deng (*) : W. Yang : G. Zhou : Y. Li : S. Liu Research and Development Center, Dongjiang Environmental Company Limited, Shenzhen 518104, China e-mail: [email protected]
issue in many countries (Heikens et al. 2001; Yang et al. 2009). During the past decades of fast growth, large quantity of industrial effluent entered the Shenzhen River. Heavy metals emitted into the aquatic environment are usually first dissolved in the water, then they adsorb to particles through relatively weak physical and chemical bonds, the particles finally sink and accumulate in the water sediments (Pempkowiase et al. 1999). The distribution of heavy metals in the bottom sediment is affected by the mineralogical and chemical composition of the suspended material, anthropogenic influences, and situational processes such as deposition, sorption, and enrichment in organisms (Jain et al. 2005). Most studies of contaminants in sediments have been focused on heavy metals, and only a few studies have focused on PAHs, which are toxic to aquatic organisms, and some of which are carcinogenic to humans (Bihari et al. 2007). Sediments are important reservoirs for many persistent organic pollutants (POPs), including PAHs, and are one of the media through which POPs enter aquaculture and wildlife food chains (Baumard et al. 1998; Hu et al. 2011). The Shenzhen River serves as the natural administrative border between Hong Kong and Shenzhen City, and locates in one of the most developed regions in China. The river is suffering from deteriorating water and sediment quality because of the increasing amounts of pollution emitted into it, as the tributaries of fast growing city of Shenzhen. Till the time of writing, the source-root-up project against pollution to the Shenzhen River Region has achieved its accomplishment, the government is moving onto the evaluation sediments contamination and corresponding recovery measures. According to recent studies, As, Cd, Cr, Cu, Hg, Ni, Pb, Zn, and PAHs often accumulate in sediments because of the effects of industrial, municipal, and mining activities (Heath et al. 2010; Milačič et al. 2010; Sharmin et al. 2009; Varol 2011). Investigation of heavy metals and PAHs in sediments can provide useful information to further our understanding of their environment fate and behavior. The normal evaluation measures are on the
Environ Sci Pollut Res
pollutant values of sample sediment in comparison to the background values and/or the authoritative standard value. However, it is now widely accepted that the roles of aquatic sediments as sinks and sources of pollutants, especially heavy metals, cannot be fully assessed by measuring the total heavy metal concentrations (Jain et al. 2004). Researchers adopt the Hakanson’s method and Effect Range Low/Effect Range Median (ERL/ERM) method in the evaluation of ecological risks of heavy metals and PAHs in the water sediments (Fu et al. 2009; Hartmann et al. 2004). The objective of the study presented here was to evaluate the quality of the sediments in the Shenzhen River, and to provide valuable reference in the planning of remediation actions. The concentrations of heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) and sixteen PAH compounds were analyzed in sediment samples, and an ecological risk assessment was performed for each chemical.
Materials and methods Site description and sediment sampling The locations of the sampling sites are shown in Fig. 1. Sample S1 was collected at the Luohu check port in the
Fig. 1 Map of the sediment sampling sites in the Shenzhen River
Shenzhen River, upstream of Shenzhen, at 114.1140° E 22.5302° N. Sample S2 was collected near the Shangbu loading area, at 114.0563° E 22.5042° N, where the sediment is alternately affected by freshwater and seawater with the changing tide. The Shenzhen and Hong Kong governments had accomplished three phases of remediation work including widening the river channel, cleaning sediment, and clearing pollution source. This study is part of the basic investigations for the fourth phase. The sediment from those spots has the best representativeness, which are the same spot of previous there phase of recover measures, and the hydrologic monitoring section of local authoritative. Sediment samples (500 L, from 0–0.5 m deep) were collected from the river bed using a clamshell sediment collector on 7 August 2012, and were stored in PTFE bags, frozen to and stored at−20 °C, until they were analyzed. The sampling procedures are in conformance with the Chinese national standard GB 17378.3-2007 (General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China 2007). Sample analysis The sediment samples analysis were carried out by a third part with China Metrology Certification, SGSC S T C S t a n d a r d s Te c h n i c a l S e r v i c e s C o . , L t d (Guangzhou, China). The sample for heavy metal concentration values is prepared according to the US Environmental Protection Agency (US EPA) Method 3050B (US EPA 1996): dispelling with HNO3-H2O2, and an amount of solid sediment 10 g was analyzed; the sample for PAHs was processed in the supersonic wave dispelling US EPA method 3550B (US EPA 1998). Cd, Cr, Cu, Ni, Pb, and Zn were determined by atomic absorption spectrometry, and As and Hg were determined by atomic fluorescence spectrometry, after acid digestion, in the appropriate China national standard methods GB/T 17138–1997, GB/T 17139–1997, GB/T 17141–2007, and HJ 491–2009 (Ministry of Environmental Protection, the People’s Republic of China 1997a; b; c; 2009) and GB/T 22105.1-2008 and 22105.2-2008 (General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China 2008a; b). The PAHs were determined by gas chromatography/mass spectrometry (GC/ MS), following China national standard method GB 5085.3-2007 (Ministry of Environmental Protection, the People’s Republic of China 2007) for semivolatile organic compounds. All data were subjected to strict quality control procedures, including analysis of method blanks, spiked blanks, and matrix spikes.
Environ Sci Pollut Res Table 1 Heavy metal concentration values (mg/kg, dry weight) in the sediment from different estuaries and comparison with quality standards
(1) (2) (3) (4) (5) (6) (7) (8) (8) (9)
Cd
Cr
Cu
Ni
Pb
Zn
Hg
As
0.81 0.88 1.5 1.5/4 1 0.1–0.5 0.08–0.64 6–14 3–10 –
129 139 80 80/160 52.3 26–54 55–802
162 194 100 65/110 18.7 24–86 4–23 28–104 20–57 110.55
107 133 – 40/40 15.9 15–35 16–45 28–40 21–39 91.12
102 82 130 75/110 30.2 35–70 5.9–21.3 281–406 125–334 11.67
659 723 350 200/270 124 88–285 39–188 105–792 91–650 87.94
0.20 0.30 0.5 0.5/1 0.13 0.09–0.18 –
11.8 12.2 65 12/42 7.24 16–20 –
– –
– –
48–91 254.52
(1) Present study S1 average concentration, (2) present study S2 average concentration, (3) marine sediment quality. China (General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China 2008a, b), (4) Technical Circular NO.34/2002. Hong Kong (Environment and Works Bureau 2002), (5) ecological screening values (U.S. EOP 1999), (6) Deep Bay. China (Environmental Protection Department 2000), (7) coastal sediments from Baja California (Mexico) and California (USA) (Villaescusa-Celaya et al. 2000), (8) Kaoping River, Tungkang River, and Lingbeng River in southwestern Taiwan (Chung et al. 2011), (9) Kabini River in Karnataka, India (Taghinia Hejabi et al. 2011)
Results and discussion Heavy metal concentrations The sediment samples from each site were divided into three subsamples for analysis, and the average concentration of the eight heavy metals in each of the samples are presented in Table 1. It can be seen that the values were fairly similar in the two samples; the highest heavy metal concentration was for Zn, at a mean of 659–723 mg/kg, Hg was found at the lowest concentrations. The values in comparison with the similar studies and corresponding quality standards indicated that Cr, Cu, Ni, Pb, and Zn in the present study exceeded the standard values of GB 18668–2002 (Ministry of Environmental Protection, the People's Republic of China 2002), Lower/Upper Chemical Exceedance Level (Hong Kong), and Ecological Screening Values (USA), which means the region’s potential ecological risk. All of the heavy metals density values were found higher than those of Shenzhen Deep Bay (China) and California coastal, investigated in 2000 and 2011, respectively. Meanwhile, Cu, Ni, Pb, and Zn values were higher than in rivers neighboring Dapeng Bay (Taiwan)
Table 2 The relationships between the integrated pollution index and the pollution degrees
and Kabini River in Karnataka (India). The results are obvious: sediments in Shenzhen Rive have higher density values than the level of the local background and other similar rivers in the world, which is suggested to have great attention. Evaluation of heavy metal pollution in sediments Hakanson’s ecological risk assessment method (Lars 1980) was adopted in evaluation of the potential ecological risks associated with the metal contaminant concentrations found in the sediment samples. The potential ecological risk index method, which uses the characteristics of the heavy metal and its environmental behavior, is an approach for evaluating heavy metal contamination from the perspective of sedimentology. It not only considers heavy metal concentrations in the soil, but also includes ecological toxicological effects, and is used to evaluate pollution in comparable and equivalentproperty-index grading methods. The potential ecological risk index is related to the individual pollution coefficient, the heavy metal toxic response coefficient, and the individual potential ecological risk coefficient, and it is calculated using the formulae:
C if
Pollution degree
E if
RI
Potential ecological risk degree
C if
