Occurrence and Source Identification of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans and Polychlorinated Biphenyls in Surface Sediments from Liangshui River in Beijing, China

Abstract

Polychlorinated dibenzo-p-dioxins and dibenzofurans and polychlorinated biphenyls were measured in the surface sediments of Liangshui River, the second largest drainage river in Beijing, China. The sum concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans and polychlorinated biphenyls ranged from 3.5 to 3019 (mean value: 184) pg g^-1 dry weight and from 319 to 5949 (mean value: 1958) pg g^-1 dry weight, and the corresponding World Health Organization toxic equivalent quantity values were 0.0011-5.1 pg TEQ g^-1 dry weight and 0.0074-1.4 pg TEQ g^-1 dry weight, respectively. The spatial distributions of polychlorinated dibenzo-p-dioxins and dibenzofurans and polychlorinated biphenyls showed increasing trends from urban area and development area to suburb. Principal component analysis revealed that polychlorinated dibenzo-p-dioxins and dibenzofurans contamination in the sediments may originate from pentachlorophenol and sodium pentachlorophenate and municipal solid waste incineration. Regarding polychlorinated biphenyls, the steel industry, combustion processes and usage of some commercial polychlorinated biphenyl products were identified as the major sources. The emission from a former steel plant could be the main contributor to polychlorinated biphenyls in urban areas. The mean value of the total toxic equivalent quantities in the sediment samples exceeded the Canadian interim sediment quality guidelines. Long-term wastewater irrigation increases the load of sediment-bound pollutants in agricultural soil and may pose potential ecological risks to crops and human health.

Keywords: Liangshui River; PCBs; PCDD/Fs; sediment.

Figure 1

Sampling sites for the surface sediments from Liangshui River (LSR) in Beijing, China.

Figure 2

Spatial distribution of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) (a) and polychlorinated biphenyls (PCBs) (b) in the three functional urban areas in Beijing. Urban area included 5 sites, L01–L05; development area included 5 sites, L06 and L22–L25; suburb included 17 sites, L07–L21 and L26–L27.

Figure 3

Percentage composition of PCDD/F (a) and PCB (b) congeners in the sediments from LSR.

Figure 4

Principal component analysis (PCA) score plot of the 2,3,7,8-substituted PCDD/F congeners in the sediments of LSR and the samples from the typical sources. Abbreviations: PCP, pentachlorophenol [44]; PCP-Na, sodium pentachlorophenate [44]; STEEL, ambient air around a steel plant [45]; Al, gaseous emission from secondary Al metallurgy [20]; Cu, gaseous emission from secondary Cu metallurgy [20]; IOS, gaseous emission from iron ore sintering plants [20]; MSWI-FS, fluvo-aquic soil near to a municipal solid waste incineration (MSWI) plant [46]; MSWI-PS, paddy soil near to a MSWI plant [46]; MSWI-F, flue gas from an MSWI plant [46]; MSWI-FA, fly ash from a MSWI plant [46]; WWPM, waste water from a pulp mill [47]; HCB, housecoal burning [48]; ASOB, agricultural straw open burning [49].

Figure 5

PCA score plot of the dioxin-like PCB (dl-PCB) congeners in the sediments of LSR and the samples from the typical sources; (a) PC1 and PC2 score plot; (b), PC1 and PC3 score plot. Abbreviations: HCB, housecoal burning [48]; HWB, hardwood burning [48]; KC, brand name of commercial PCB formulations, Kanechlor [51]; Ar, brand name of commercial PCB formulations, Aroclor [52]; Al, gaseous emission from secondary Al metallurgy [20]; Cu, gaseous emission from secondary Cu metallurgy [20]; IOS, gaseous emission from iron ore sintering plants [20]; WWTP, sewage sludge of urban wastewater treatment plants [39]; STEEL, ambient air around a steel plant [45]; MSW, municipal solid waste [53].

Figure 6

Comparison between the total toxic equivalent quantity (TEQ) of PCDD/Fs and PCBs in the sediments from LSR and the Canadian interim sediment quality guidelines (ISQGs).