Distribution characteristics and source of BTEX in groundwater in Guangzhou,Guangdong Province,P.R.China

In order to find out the distribution characteristics of BTEX in groundwater, which include Benzene, Toluene, Ethylbenzene, p-Xylene, m-Xylene, and o-Xylene, 82 groups of groundwater samples and 10 surface water samples collected from Guangzhou in Guangdong during 2005 to 2008 were tested by gas chromatography and mass spectrum(GC/MS). The result showed that the BTEX concentration in groundwater does not exceed the standard. The detection rate of BTEX is 14.63% in groundwater, and the total BTEX concentration is lower than 9.5 μg/L. Of 6 kinds of BTEX, toluene had the highest detection rate(12.20%) and detection value(9.5 μg/L), which was followed by Benzene, with the detection rate of 3.65%, and detection value of 4.9 μg/L respectively; most of samples with BTEX are distributed in Huangpu district, Baiyun district, Huadu district and other industrialized areas; this spatial distribution and urban distribution have obvious consistency. With economic development, plant expansion and population growth led to a large amount of waste water discharge, and infrastructure construction is lagging behind, indicating that rapid urbanization is a major driving force of BTEX in groundwater, and through the analysis of a typical area, it is found that benzene system surface water infiltration was an important source of BTEX in groundwater of Guangzhou.

An analysis of vehicular exhaust derived nanoparticles and historical Belgium fortress building interfaces

Air pollution monitoring is one of the most important features in contamination risk management.This is because many of the compounds contained within air pollution present a serious risk both for the preservation of open air cultural heritage and for human health.New particle formation is a major contributor to urban pollution,but how it occurs in cities is often puzzling.As more and more people enjoy an increased quality of life through outdoor activity,managing outdoor air quality is vital.This study presents the application of a low-cost system for monitoring the current level of road traffic passengers’exposure to particulate air contamination.The global rise in tourism also leads to apprehension about its probable destructive influence on various aspects of global preservation.One of the major risks encountered by tourists,stemming from modes of transport,are nanoparticles(NPs)(<100 nm)and ultra-fine particles(UFPs)(100-1000 nm)consisting of potentially hazardous elements(PHEs).This study examines Steen Castle,a medieval fortress located in Antwerp,Belgium.Significant NPs with PHEs,were found in the air sampled in this area.The self-made passive sampler(LSPS)described in this study,consisting of retainers specially designed for advanced microscopic analysis,is used for the first time as a simple way to characterize the surrounding atmospheric contamination caused by NPs and UFPs,without the need of other commonly employed more expensive particulate focused active samplers such as cascade impactors.This study aims to assess the result of the utilization of a low-cost,LSPS,to determine outdoor NPs and UFPs in a Belgian urban(Steen Castle)and rural area(Fort van Schoten).This work is the first to detail the usefulness of LSPS for the evaluation of Belgium’s outdoor air for NPs and UFPs,which contain PHEs.

Experim ental investigation of sound propagation from an impulsive source near rigid wedges

The acoustic signal from an impulsive source near an ideal rigid wedge consists of the reflected waves from the inclined plane and the diffracted waves from the apex of the wedge. There are two theoretical solutions of the problem. The first was obtained by Biot-Tolstoy using normal coordinates. The second was Trorey's Helmholtz-Kirchhoff solution. So far the experimental measurements have concentrated on the diffracted wave from the wedge apex and ignored the rest of the solution. The Biot-Tolstoy exact wedge solution is used in this paper to study the sound transmission in wedges of angle 12 °and 52 °approximately. The theory and the experiments are consistent. Also studied is the behaviour of the reflected and diffracted waves from a 270 °wedge. Both theories predicted the existence a specular ' image ' reflection when a coincident source and receiver are over a half plane. The experimental results showed that the Biot-Tolstoy theory was accurate and the Trorey solution produced quite large errors.