Hong-Gang Ni

Organochlorine pesticides and polychlorinated biphenyls in riverine runoff of the Pearl River Delta, China: assessment of mass loading, input source and environmental fate.

A large-scale sampling program was conducted to simultaneously collect water samples at the eight major riverine runoff outlets of the Pearl River Delta (PRD), South China to assess the importance of riverine runoff in transporting anthropogenic pollutants from terrestrial sources to the coastal ocean. The concentrations of Sigma21OCPs (sum of 21 OCP components) and Sigma20PCBs (sum of 20 PCB congeners) were 2.57-41.2 and 0.12-1.47 ng/L, respectively. Compositional distributions of DDTs suggested the possibility of new input sources in the study area, but contributions from dicofol seemed considerably low. The annual inputs of Sigma21OCPs and Sigma20PCBs were 3090 and 215 kg, with those of total HCHs and DDTs being 1110 and 1020 kg, respectively. A mass balance consideration indicated that riverine runoff is the major mode carrying OCPs from the PRD to the coastal ocean, and the majority of OCPs is further dissipated to open seas.

ENVIRONMENTAL AND HUMAN EXPOSURE TO PERSISTENT HALOGENATED COMPOUNDS DERIVED FROM E-WASTE IN CHINA

Various classes of persistent halogenated compounds (PHCs) can be released into the environment due to improper handling and disposal of electronic waste (e-waste), which creates severe environmental problems and poses hazards to human health as well. In this review, polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs), tetrabromobisphenol A (TBBPA), polybrominated phenols (PBPs), polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs), and chlorinated polycyclic aromatic hydrocarbons (ClPAHs) are the main target contaminants for examination. As the worlds largest importer and recycler of e-waste, China has been under tremendous pressure to deal with this huge e-waste situation. This review assesses the magnitude of the e-waste problems in China based on data obtained from the last several years, during which many significant investigations have been conducted. Comparative analyses of the concentrations of several classes of toxic compounds, in which e-waste recycling sites are compared with reference sites in China, have indicated that improper e-waste handling affects the environment of dismantling sites more than that of control sites. An assessment of the annual mass loadings of PBDEs, PBBs, TBBPA, PBPs, PCDD/Fs, and ClPAHs from e-waste in China has shown that PBDEs are the dominant components of PHCs in e-waste, followed by ClPAHs and PCDD/Fs. The annual loadings of PBDEs, ClPAHs, and PCDD/Fs emission were estimated to range from 76,200 to 182,000, 900 to 2,000 and 3 to 8 kg/year, respectively. However, PCDD/Fs and ClPAHs should not be neglected because they are also primarily released from e-waste recycling processes. Overall, the magnitude of human exposure to these toxics in e-waste sites in China is at the high end of the global range.

Riverine inputs of total organic carbon and suspended particulate matter from the Pearl River Delta to the coastal ocean off South China

A total of 1008 samples were collected from the eight major riverine runoff outlets in the Pearl River Delta (PRD) during 2005-2006 to estimate the fluxes of total organic carbon (TOC) to the coastal ocean off South China. The average dissolved organic carbon (DOC) concentration was 1.67 mg/L with a range of 1.38-2.13 mg/L. Concentrations of particulate organic carbon (POC) ranged from 2.66-4.12% of total suspended particulate matter (SPM). The fluxes of TOC and SPM from the PRD via the eight outlets were 9.2 x 10(5) and 2.5 x 10(7)tons/yr, respectively. Temporal variations in POC and DOC were observed at all outlets due to the large variability in runoff levels because of the seasonality of rainfall, and the riverine discharge amount was an important factor controlling TOC flux. The net contribution of organic carbon from the PRD to the coastal ocean represented approximately 0.1-0.2% of total organic carbon transported by rivers worldwide.

Halogenated polycyclic aromatic hydrocarbons in the environment.

Halogenated polycyclic aromatic hydrocarbons (HPAHs) have been reported to occur in air, sediment, fly ash, and biota samples. This review summarized current existing data on the environmental occurrence, behavior, physicochemical properties, emission sources, and toxic equivalents of HPAHs. Firstly, the physicochemical properties of HPAHs were summarized. Then, an overview of environmental occurrence of HPAHs in ambient matrices including biological samples was reviewed. Meanwhile, the emission sources and possible formation mechanisms of HPAHs were discussed. Apart from that, the aryl hydrocarbon receptor (AhR)-mediated activities were summarized, which indicated that the position and number of halogen atoms on the parent PAHs molecule were important determinant factors affecting the AhR-mediated activity of individual HPAHs congeners. Finally, some research recommendations on HPAHs were given.

Parent and halogenated polycyclic aromatic hydrocarbons in rice and implications for human health in China.

Rice is the staple food for approximate two thirds of the Chinese population. However, human exposure to parent and halogenated polycyclic aromatic hydrocarbons (PAHs) via rice consumption is still not clear for Chinese people so far. The goals of this work are to assess human exposure to PAHs and halogenated PAHs (HPAHs) via rice ingestion and the cancer risk for Chinese population. 16 PAHs and eight HPAHs were determined in rice samples collected from 18 provinces in China. In general terms, the general population in China was exposed to higher levels of PAHs via rice ingestion in comparison to that via cereals for other countries. The cancer risk values induced by exposure to PAHs and HPAHs for male and female on each age group were between the priority risk level (10(-4)) and the acceptable risk level (10(-6)). Children faced the highest cancer risk, followed by adolescents and adults.

Incidence of polybrominated diphenyl ethers in central air conditioner filter dust from a new office building.

This study examined polybrominated diphenyl ethers (PBDEs) in central air conditioner filter (CACF) dust from a new office building in Shenzhen, China. Human exposure to PBDE via dust inhalation and ingestion were also estimated. PBDEs level in CACF dust was lower than those in the other countries and regions. Approximately 0.671 pg/kg bw/day PM(2.5) (Particulate Matter up to 2.5 μm in size) bounded Σ(15)PBDEs can be inhaled deep into the lungs and 4.123 pg/kg bw/day PM(10) (Particulate Matter up to 10 μm in size) bounded Σ(15)PBDEs tend to be deposited in the upper parts of the respiratory system. The average total intake of Σ(15)PBDEs via dust inhalation and ingestion for adults reached ∼ 141 pg/kg bw/day in this building. This value was far below the reference dose (RfD) recommended by United States Environmental Protection Agency. Human exposure to PBDEs via dust inhalation and ingestion in the new building is less than the old ones.

Occurrence, bioaccumulation and potential sources of polybrominated diphenyl ethers in typical freshwater cultured fish ponds of South China

To determine the potential input sources of polybrominated diphenyl ethers (PBDEs) to fish farming environments in South China, samples of seven various environmental matrices were collected from October 2006-September 2007. Tri- to deca-BDEs were detected in all samples analyzed, with mean concentrations (+ or - standard deviations) at 5.7 + or - 3.6 ng/L in pond water, 15 + or - 11 ng/g dry wt. in pond sediment, 12 + or - 3.8 ng/g dry wt. in bank soil, 21 + or - 20 ng/g lipid wt. in fish, and 93 + or - 62 ng/g lipid wt. in fish feeds. In addition, BDE-209 was the major constituent in all samples except fish and BDE-47 was predominant in fish samples. Relatively high abundances of BDE-49 were detected in all the samples compared to those in the penta-BDE technical products. Several bioaccumulation factors were evaluated. Finally, statistical analyses suggested that fish feed, as well as pond water at a lesser degree, may have been the major source of PBDEs in freshwater farmed fish.

Human exposure to parent and halogenated polycyclic aromatic hydrocarbons via food consumption in Shenzhen, China

Human exposure to polycyclic aromatic hydrocarbons (PAHs) and halogenated PAHs (HPAHs) via food consumption is still not clear in south China so far. The goals of this work are to assess human exposure to parent and halogenated PAHs via food ingestion and the cancer risk for population in Shenzhen, a new urban center in south China. Sixteen PAHs and nine HPAHs were determined in vegetable, pork and rice samples collected from Shenzhen. In general, the population in Shenzhen was exposed to higher levels of PAHs via food ingestion in comparison to that reported for other countries in recent years, but lower than that estimated for two northern cities in China. The cancer risk values induced by exposure to PAHs and HPAHs for male and female on each subgroup were between the serious risk level (10(-4)) and the acceptable risk level (10(-6)). Children faced the highest cancer risk, followed by adolescents, seniors and adults.

Occurrence and human non-dietary exposure of polycyclic aromatic hydrocarbons in soils from Shenzhen, China

Twenty eight polycyclic aromatic hydrocarbons (PAHs) were determined for a total of 203 top soil samples collected from eight different land categories in Shenzhen, China during the winter of 2007. The concentrations, compositional profile, and the potential sources of PAHs in soil were discussed. Overall, PAH pollution in the soil of Shenzhen is still in the low-end of the world after 30 years rapid urbanization. Based on that, human exposure to soil PAHs via inhalation and soil particle intake were estimated as well. The concentrations of Sigma(28)PAHs in Shenzhen soil ranged from 2.68 to 17,767 ng g(-1) (average: 546 ng g(-1)). The highest levels of PAHs were found in the traffic land (average: 2104 ng g(-1)) and the lowest concentrations were detected in forest land (average: 144 ng g(-1)) in eight land categories. PAH isomeric ratios indicated that PAHs in Shenzhen soil were mainly derived from combustion. In the current pollution levels in Shenzhen, children aged 0 to 8 were the most sensitive sub-group of exposure to PAHs (59.2 ng (kg d)(-1)), and the exposure to PAHs for males (36.2 ng (kg d)(-1)) was more serious than for females (32.7 ng (kg d)(-1)). Inhalation was the major way of non-dietary exposure (over 96%).

Environmental and human exposure to soil chlorinated and brominated polycyclic aromatic hydrocarbons in an urbanized region

Nine chlorinated and brominated polycyclic aromatic hydrocarbons (Cl/BrPAHs) and five parent polycyclic aromatic hydrocarbons (PAHs) were measured in urban surface soil and fly ash samples collected from Shenzhen, south China in winter 2010. The concentrations of total Cl/BrPAHs and PAHs in soil ranged from below the reporting limit to 142 ng/g and from 4.34 to 158 µg/g, respectively, and in fly ash they ranged from 17.7 to 19.5 ng/g and 26.1 to 28.3 µg/g, respectively. Concentrations of Cl/BrPAHs and parent PAHs were not significantly correlated with each other in soil or in fly ash, suggesting that Cl/BrPAHs were formed mainly by mechanisms other than direct halogenation of parent PAHs. Estimated mass inventories of 2-BrFlu varied from 68.1 kg in commercial land to 669 kg in countryside land, the highest among all Cl/BrPAHs. Loss fluxes via soil erosion accounted for only small proportions of total soil mass inventories of Cl/BrPAHs. Average daily human intake via soil ingestion decreased with increasing age, with 2-BrFlu as the main contributor. Children of 0 to 8 years old were the most sensitive subgroup (13.7 pg/kg body wt/d for total Cl/BrPAHs), and females were more sensitive than males in the same age group. The mean dioxin-like toxic equivalency quotient (TEQ) concentration of total Cl/BrPAHs (0.008 ng-TEQ/g) was lower in soil than in fly ash (0.06 ng-TEQ/g). Conversely, the mean TEQ concentration of total parent PAHs (2.23 ng-TEQ/g) was higher in soil than in fly ash.