[Pollution Characteristics and Health Risk Assessment of Polycyclic Aromatic Hydrocarbons in the Surface Soils of a Large Steel enterprise in the North of China].

16 priority control polycyclic aromatic hydrocarbons (PAHs) were analyzed by GC-MS in 22 surface soil (0-20 cm) samples collected from a large steel enterprise in the north of China. The concentrations of Σ16PAHs ranged from 22.0 µg·kg-1 to 20062.0 µg·kg-1. 4 to 5 aromatic rings were the dominant, typically fluorene(Flu) and pyrene(Pyr). Compared with related domestic research, PAH pollution in the steel enterprise reached medium level, with fifty percent of the soil points were at moderate and severe pollution levels, mainly in the coking and pellet plant area. The concentrations of 10 PAHs in 20 soil samples exceeded the Dutch target reference values. Compared with soil screening value of Beijing contaminated industrial sites, only part of the sample points exceeded the standard, typically benzo[a]anthracene(BaA) and benzo[a]pyrene(BaP). The source apportionment showed that soil PAHs mainly originated from combustion products of coal and other fossil fuels with only a small portion contributed by oil combustion and spill. The health risk assessment showed that the carcinogenic risks of benzo[a]pyrene(BaP), benzo[a]anthracene(BaA), dibenz(a,h)anthracene(DBA), benzo[b]fluoranthene(BbF), indeno[1,2,3-cd]pyrene(InP) exceeded the threshold of 1×10-6 under residential land condition, the carcinogenic risks of benzo[a]pyrene(BaP), benzo[a]anthracene(BaA), dibenz(a,h)anthracene(DBA) also exceeded the threshold of 1×10-6 under industrial land condition. The carcinogenic risk value of benzo[a]pyrene(BaP) was the biggest among the 16 PAHs. The soil PAHs in the steel enterprise already caused harm to human health and the soil restoration project must be carried out.

[Speciation and Risk Assessment of Heavy Metals in Surface Sediments from the Heavily Polluted Area of Xiaoqing River].

Th concentrations of Cu, As, Pb, Zn, Cr, Cd, Ni in interstitial water were analyzed by ICP-MS from the heavily polluted area of Xiaoqing River. A modified BCR's sequential extraction procedure was used to investigate the fraction of the heavy metals in the surface sediments. The aquatic toxicity of heavy metals in interstitial water was assessed by US Water Quality Criteria (CCC, CMC). Based on the speciation of the metals in the surface sediments, the ecological risk of heavy metals was assessed with methods of risk assessment code (RAC) and potential ecological risk index. The results showed that: The tested heavy metals would not pose chronic toxicity for aquatic ecosystem. The contents of heavy metals (Cu, Pb, Zn, Cr, Cd, Ni) in the surface sediments were higher than the background values of the local soils, indicating enrichment of heavy metals. Cu, As and Ni were mainly composed with residual fractions, Pb and Cr were mainly constituted of residual and oxidizable fractions, and mass fractions of Zn and Cd existed mainly in acid soluble and reducible factions. The contents of bio-available fractions of Cd, Zn, Cr and Pb in the sediments were higher those of residual fractions, indicating high potential for secondary release. Based on calculation of RAC method, Cu, Pb, Cr and As posed extremely low to low risk to the environment. Accordingly, Ni was of low to medium risk, Cd was of medium to high risk, and Zn was of medium to extremely high risk to the environment. The potential ecological risk of heavy metals in the sediments was in the descending order of Cd > Zn > Ni > As > Cu > Cr > Pb. Cd had high to very high potential ecological risk comparing with the other heavy metals. The potential ecological risk indexes (RI) of the heavy metals in the sediments were in the range of 136.83-264.83, and posed medium to high potential ecological risks for Xiaoqing River.

[Study on removal rule of endosulfan in surface flow constructed wetland].

Endosulfan is a kind of widespread organochlorine pollutant in the environment. The removal rule of three different concentrations of endosulfan in different parts of a surface flow constructed wetland was investigated. The concentrations of endosulfan in water, plants, non-rhizosphere sediments and rhizosphere sediments were determined by the Soxhlet extraction-GC method. The results showed that constructed wetland was efficient in endosulfan removal. The removal rate of endousulfan in water, non-rhizosphere sediments and rhizosphere sediments was 87.9%, 63.0% and 70.9%, respectively. In this system, alpha-endosulfan was removed faster than beta-endosulfan and the metabolite accumulated was mainly endosulfan sulfate. The adsorption of sediments played an important role in the removal of endosulfan. About 80.0% of endosulfan in water could be adsorbed by sediments within three days. The removal rate of endosulfan could be enhanced by plants. Because of the effect of plants, the average removal rate of endosulfan in rhizosphere sediments was 7.9% higher than that in non-rhizosphere sediments.