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The distribution, pollution level and health risk of Cu, Pb, Zn, Mn, Co, Ni, Cr and Cd in urban street dust are investigated. The average concentration of heavy metals is 246.47, 329.89, 511.16, 620.26, 9.57, 80.55, 97.16 and 2.50mg/kg for Cu, Pb, Zn, Mn, Co, Ni, Cr and Cd, respectively. Compared with background values of Chengdu and Chinese soils, the heavy metal contents of street dust in Chengdu were all much higher except Co. The enrichment factor results reveal the following order: Cd>Pb >Cu>Zn >Ni>Cr>Co. Cu and Zn of street dusts is mainly moderate contamination. Pb and Cd is significant contamination. Co, Ni and Cr is the lack of contamination as a whole, expecially Co. Non-carcinogenic effects and carcinogenic effects due to exposure to urban street dusts were assessed for both children and adults. For non-carcinogenic effects, ingestion was the main route of exposure to street dusts for these metals, followed by dermal contact and inhalation except Co (ingestion>inhalation> dermal contact). Hazard index (HI) values for all studied metals were lower than the safe level of 1. The carcinogenic risk for Co, Ni, Cr and Cd were all below the acceptable level (<10-6). [ABSTRACT FROM AUTHOR]

Street dusts of different functional areas from Chengdu, SW China are analyzed for Cu, Pb, Zn, Mn, Co, Ni, Cr and Cd. The results show that, in comparison with the background values of Chengdu and Chinese soils, the mean concentrations of all heavy metals are all higher than their corresponding background values of Chengdu soil and Chinese soil except Co and the street dusts from seven functional areas have different cumulative characteristics. Meanwhile, the value of Igeo, PI, IPI and RI are calculated. The results indicate that the order of Igeo is Cd>Pb>Cu>Zn>Ni>Cr>Mn>Co and the Igeo of heavy metals in the dust from TD and ID is higher than in other functional areas. The high Igeo for Cu, Pb, Zn, Ni and Cd in street dusts indicate that there is a moderate or strong Cu, Pb, Zn, Ni and Cd pollution. Igeo for Mn, Co and Cr are less than 0, indicating that the urban environment was scarcely contaminated by Mn, Co and Cr. The assessment results of PI also support Cu, Pb, Zn, Ni and Cd in street dusts presented serious pollution, and IPI indicates heavy metals of street dust polluted seriously. the RI values of heavy metals indicate the heavy metals of street dusts are considerable ecological risk or very high ecological risk and Cu, Pb and Cd are the main contributors to the potential ecological risk, especially Cd. [ABSTRACT FROM AUTHOR]

The phosphorus fractions and phosphate sorption and release characteristics of the street dusts from Chengdu City were investigated. The results indicated that the total phosphorus (TP) contents in the street dusts varied from 0.58mg/g to 0.84mg/g; inorganic phosphorus (IP) was the major fraction of TP; Calcium bound phosphorus (Ca-P) was the main fraction of IP. For all the street dusts samples, the rank order P-fractions was Ca-P> organic phosphorus (OP)>Phosphorus bound to Al, Fe, and Mn oxides and oxyhydroxides (Fe/Al-P). Phosphate sorption on the street dusts mainly occurred within 3h and then reached to equilibrium in 14h. The phosphate sorption capacity ranged from 194.78mg/kg to 945.81mg/kg and the phos-phate sorption efficiency ranged from 57.17 L/kg to 330.86L/kg; there was no significant correlation between street dust compositions and the maximum phosphate sorption capacity, phosphate sorption efficiency. The amounts of P released from the street dusts were strongly in positive correlations with the contents of Fe/Al-P and OP. It indicated that Fe/Al-P and OP were main released fractions, and it can release P easily. [ABSTRACT FROM AUTHOR]

Abstract: Based on the 24-hour monitoring results of quality and quantity of wastewater discharged from the expressway service area, a three-step feeding A/O biological contact oxidation process was employed to treat the expressway service area wastewater which was of high-strength COD and total Kjeldahl nitrogen (TKN). By two stages continuous experiment, the treatment effect of the process to the high-strength COD and TKN wastewater was studied. The experiment results indicated, when the three-step feeding A/O biological contact oxidation process employed to treat the high-strength COD and TKN wastewater, alkalinity was a decisive factor for the treatment effect of the process. When COD, TKN, ammonia nitrogen and total nitrogen (TN) concentrations of the influent were 1030mg/L, 212mg/L, 153mg/L and 213mg/L respectively, and HRT was 36hours, the removal efficiencies of the process to COD, TKN, ammonia nitrogen and total nitrogen were higher than 95%, 98%, 98% and 80% respectively. The effluent quality was superior to the first discharge standard of integrated wastewater discharge standard (GB8978-1996). [Copyright &y& Elsevier]