Coastal Water Quality Assessment by Self-Organizing Map

A new approach to coastal water quality assessment was put forward through study on self-organizing map （ SOM ）. Firstly, the water quality data of Bohai Bay from 1999 to 2002 were prepared. Then, a set of software for coastal water quality assessment was developed based on the batch version algorithm of SOM and SOM toolbox in MATLAB environment. Furthermore. the training results of SOM could be analyzed with single water quality indexes, the value of N ： PC atomic ratio） and the eutrophication index E so that the data were clustered into five different pollution types using k-means clustering method. Finally, it was realized that the monitoring data serial trajectory could be tracked and the new data be classified and assessed automatically. Through application it is found that this study helps to analyze and assess the coastal water quality by several kinds of graphics, which offers an easy decision support for recognizing pollution status and taking corresponding measures.

Characteristics of bioaerosols under high-ozone periods,haze episodes,dust storms,and normal days in Xi'an,China

The characteristics of bioaerosols and their effects on human beings'health have become a major public concern in the recent years.This study compared the characteristics of bioaerosols under different types of pollution(high-ozone[HO]episodes,haze episodes,and dust storms[DSs]),with those of bioaerosols on normal days(NDs)in Xi'an,China.The concentrations,diurnal variations,and size distribution of bacteria,fungi,and total airborne microbes(TAMs)were investigated.The results showed that the bacterial and fungal concentrations were the highest during DSs and on NDs,reaching 425.2 and 956.9 colony-forming units/m^(3),respectively.The concentration of TAMs was the highest during HO episodes,reaching 10.7×10^(6)cells/m^(3),which was significantly higher than that during the other events.The maximum concentrations of bacteria and fungi during HO episodes were observed in the morning,while they appeared separately in the morning and evening during haze episodes.Bacteria and TAMs during DSs reached peak concentrations in the morning and evening,which is opposite to the particulate matter(PM)distribution pattern.On NDs,temperature and relative humidity had significant effects on bioaerosols.The size distributions of airborne bacteria exhibited bimodal patterns,whereas unimodal distributions were observed for fungi.Fungi mainly attached in fine particles(<2.1μm)with proportions of 67.4%and 60.5%during haze episodes and DSs,respectively,which means that fungi were easily penetrated into the human respiratory system.The evaluation of influence factors revealed that PM_(2.5) and PM10 had negative effects on fungal concentration during DSs,and ozone concentration and temperature were inversely correlated with fungal concentration during HO episodes.These results provide valuable reference data for elucidating the formation and evolution of bioaerosols under different types of pollution.