Objective To investigate the contamination of Cd,Pb,Cu and Cr in the sediment of Guangzhou reach in Pearl River.Methods The sediments were collected in Yagang spot in April,2006.The content of heavy metals were determined,the heavy metals in the sediment were extracted with Tessier five stage sequential extraction procedure,and AAS was applied to determine the concentration of heavy metals in the sediment and extracts.Results The level of Cd,Pb,Cu,Cr were 2.29 mg/kg,217.97 mg/kg,320.60 mg/kg and 124.44 mg/kg respectively in the sediment in Yagang spot.They were higher than the background values of soil of Guangdong,and different heavy metals had different values of five forms.Cd existed as exchanged form mainly,and Cr,Pb existed as stable form mainly,so,Cd was easy to be resolved into water,Cr,Pb were relatively stable in the sediment.Conclusion The ecological risk of the four heavy metals is assessed with Hakanson potential ecological harmful index,the ecological risk of Cd is high,Cr,Pb is lower,Cu is moderate.

OBJECTIVE To understand the disinfection,use and management of ventilator for the sake of regulation.METHODS By interviewing and on-site survey,we understanded the method and the process of disinfection and found out the using cycle of the ventilator system and the conditions of its management.RESULTS Among 44 ventilators 7 models were found:the management of 18 ventilators was irregular;the other 26 ventilators were disinfected by 2 kind and 4 types disinfect methods.their using cycles were unsure,their processes of disinfection were irregular.The responsibilities for the disinfection were unclear,lacking of monitoring the effect of disinfection and their management was irregular.CONCLUSIONS The disinfection of ventilator using and management must be regulated.