Biomedical subjects

Zhi-shi Wang

Publications and source records attributed to Zhi-shi Wang.

4 recordsLinked to original sources

PubMed2006

[Choice experiment method and its application to solid waste management in Macao].

Economic valuation of environmental goods or services has been becoming a research frontier and hotspot of environmental economics in the world. Choice experiment (CE) is a relatively new method that can be used to value the economic benefits of environmental goods or services. This paper reports an attempt to apply the CE method in Macao that aimed to understand Macao residents' preferences for solid waste management programs. A random sample survey of 260 respondents in Macao was conducted during the summer in 2004. Survey data was analyzed using multinomial logit models. Results from 260 in-person interviews indicate that Macao residents preferred waste segregation and recycling at source and noise reduction during waste collection and transportation. The study concludes that CE is a reliable tool in the analysis of respondents' preferences for the development of suitable solid waste management programs in Macao.

Costs and Cost Analysis↗

PubMed2006

[Characterization of urban surface runoff in two urban catchments in Macau].

Characteristics of pollutants from urban surface runoff were investigated. Two catchments with a seperated system in Macau were selected for sampling on rainfall events during the period of August to November, 2005. Water quality parameters such as pH, turbidity, TSS, COD, TOC, TN, TP, Zn, Pb, and Cu were analyzed. The results show that the commercial-residential urban catchment shows high level of COD, TN, TP, and the park urban catchment has high TN and TP concentration. From the pollutograph analysis, the peak of TSS, TN, TP concentration appears in the first and the third sample respectively in ELH and YLF catchments, and then the pollutants concentration tend to decrease. Regression analysis between TSS and TN & TP in two urban catchments resulted in a high value (R2 > 0.95) of the coefficient of determination R2 indicating a close relationship between soil losses and nitrogen & phosphorus discharged from surface runoff. The profile of TSS and COD discharged from surface runoff relates greatly to the surface flow change, whereas the surface flow change has little influence on the profile of TN and TP. The heavy metals such as Zn, Pb and Cu fluctuate with the continuous input of vehicles during rainfall events. Pollutants such as TSS, TN, COD discharged from surface runoff depend greatly on the dry periods and storms intensity in such two urban catchments.

Cities↗

PubMed2004

[Study on on-board measurements and modeling of vehicular emissions].

It's a basic work to study the characteristics of vehicular emissions and give emission factors for development of vehicular emission inventory and decision-making of the control strategies. On-board emission measurements of on-road vehicles are regarded as important complementary to emission laboratory dynamometer tests. On-board exhaust emission measurements were conducted on seven samples of gasoline cars in a typical road in Macao, using AVL DiGas 4000 light five-gas analyzer. It was found that there was an obvious reduction of gaseous pollutant emissions from cars equipped with electronic fuel injection and three-way catalytic converter system (referred to as EFI cars in the following), compared to old carburetor cars. The average volume concentrations of CO, HC and NO of carburetor cars were 227 x 10(-6), 1.57% and 1477 x 10(-6), respectively, while those of EFI cars were 33 x 10(-6), 0.21% and 131 x 10(-6), which were about 1/11 through 1/7 of the former. However, there were high emissions during the cold start of EFI cars. The arithmetical mean concentrations of CO and NO emissions of EFI cars were calculated and their absolute values were predominantly contributed by high concentrations with low frequency. Furthermore, the emission factors of gasoline cars were estimated by test data, and at the same time, MOBILES model was used to calculate average emission factors of gasoline cars in Macao in 2000. The ratios between the results calculated by model and estimated by experiment data were in the range of 59%-139%, which would narrow into 68%-132% if only annual average emission factors were compared. The results suggest that EFI + TWC systems equipped in vehicles have good effect on the emission reduction, but catalytic converters are not activated during the cold start. Technical improvement of EFI cars, which could reduce the occurrence of high emissions with low frequency during the operation, would decrease their average level on exhaust emissions a lot. Furthermore, it's reliable that the emission factors of gasoline cars in Macao calculated by modified MOBILES model.

Air Pollutants↗

PubMed2004

[Primarily study of alkylphenols in sediment core from Nam Van artificial lake of Macao].

Alkylphenols, nonylphenols (NPs), octylphenol (OP), are known to have estrogenic effects. In a sediment core from Nam Van artificial lake of Macao, the concentrations of NPs ranged from 2.17 to 5.91 microg/g, with mean value of 3.66 microg/g during the estuarine sedimentary environment from 1970s-1980s and from 0.69 to 3.04 microg/g, with mean value of 2.08 microg/g during lagoon sedimentary environment in 1990s. The concentrations of OP during the initial stages of lagoon environment in the early 1990s were similar to that in the estuarine environment, and ranged from 14.33 to 39.11 ng/g. Subsequently, the concentration of OP was rapidly decreasing from 6.52 to 2.58 ng/g. Sources of APs in the estuarine condition included the urban runoffs from the upstream waters of Pearl River Delta and Macao city, but just from Macao in the lagoon condition. Consequently, concentration of APs in estuary condition was higher than that in lagoon condition. The vertical profile of concentration of APs in the sediment core, to some degree, was correlated with the development degree of regional economy and the proceeding of wastewater treatment. The results also showed that the alkylphenols in overlapping silty layer preferred to transfer downward to filling sandy layer.

Geologic Sediments↗