[Source and distribution characteristic of atmospheric organochlorine pesticides in the Pearl River Estuary and adjacent South China Sea].

Ship-board air samples were collected during the winter and spring cruise to the Pearl River Estuary (PRE) and adjacent South China Sea (SCS) in 2003 and were analyzed for organochlorine pesticides (OCPs). Meanwhile, air samples were collected at land-based sites in Guangzhou and Zhongshan for comparison. Results indicated that the detected OCPs were mainly of HCHs, DDTs and chlordane, its concentration ranged between 13-99, 73-390, 63-224 pg/m3 and 10-106, 429-1003, 1724-9638 pg/m3 during the winter and spring cruise, respectively. In general, the concentrations of OCPs were higher during spring cruise than in winter cruise. The measured OCPs concentration in the atmosphere over the PRE and adjacent SCS were found higher at sites close to continent and lower in outer sea, it is suggested that land-based source were to play a key role in the delivery of atmospheric OCPs. The alpha-HCH concentrations had significantly declined, higher gamma-HCH level may attribute to the present usage of lindane. Dicofol application and antifouling paints for fishing ships was suggested to be the important current "fresh" DDT source. The observed high level of chlordane during spring cruise could be related to the large amount usage of chlordane for termite control, as well as the long range transport from the west pacific region.

[Occurrence, distribution and fate of antibiotics in sewage treatment plants].

Occurrence and distribution of eight selected antibiotics were screened at four sewage treatment plants (STPs). Individual concentrations in raw influent and final effluent from the four STPs ranged from 16 to 1987 ng x L(-1) and from 16 to 2054 ng x L(-1), respectively. The other analytes were only detected in a few samples with lower concentrations. Antibiotics can not be removed completely at the four STPs with the highest removal efficiency reaching to 81%. Remarkable differences of the daily environmental loads (the sum of the amount in the final effluent and sludge) of the five most frequently detected compounds at the four STPs were found with mass data ranging from 0.5 to 828 g. The daily consumption per person in the charged area of selected STPs showed that more compounds, especially the erythromycin-H2O, were consumed each day in Guangzhou than in Hong Kong.

Characterizing ionic species in PM2.5 and PM10 in four Pearl River Delta cities, south China.

PM2.5 and PM10 samples were collected at four major cities in the Pearl River Delta (PRD), South China, during winter and summer in 2002. Six water-soluble ions, Na+, NH4+, K+, Cl-, NO3- and SO4(2-) were measured using ion chromatography. On average, ionic species accounted for 53.3% and 40.5% for PM2.5 and PM10, respectively in winter and 39.4% and 35.2%, respectively in summer. Secondary ions such as sulfate, nitrate and ammonium accounted for the major part of the total ionic species. Sulfate was the most abundant species followed by nitrate. Overall, a regional pollution tendency was shown that there were higher concentrations of sulfate, nitrate and ammonium in Guangzhou City than those in the other PRD cities. Significant seasonal variations were also observed with higher levels of species in winter but lower in summer. The Asian monsoon system was favorable for removal and diffusion of air pollutants in PRD in summer while highly loading of local industrial emissions tended to deteriorate the air quality as well. NO3-/SO4(2-) ratio indicated that mobile sources have considerably contribution to the urban aerosol, and stationary sources should not be neglected. Besides the primary emissions, complex atmospheric reactions under favorable weather conditions should be paid more attention for the control of primary emission in the PRD region.

Determination of selected antibiotics in the Victoria Harbour and the Pearl River, South China using high-performance liquid chromatography-electrospray ionization tandem mass spectrometry.

Nine selected antibiotics in the Victoria Harbour of Hong Kong and the Pearl River at Guangzhou, South China, were analyzed using high-performance liquid chromatography-electrospray ionization tandem mass spectrometry. The results showed that the concentrations of antibiotics were mainly below the limit of quantification (LOQ) in the marine water of Victoria Harbour. However, except for amoxicillin, all of the antibiotics were detected in the Pearl River during high and low water seasons with the median concentrations ranging from 11 to 67 ng/L, and from 66 to 460 ng/L, respectively; and the concentrations in early spring were about 2-15 times higher than that in summer with clearer diurnal variations. It was suggested that the concentrations of antibiotics in the high water season were more affected by wastewater production cycles due to quick refreshing rate, while those in the low water season may be more sensitive to the water column dynamics controlled by tidal processes in the river.

[Occurrence and seasonal changes of antibiotics in the Victoria Harbour and the Pearl River, South China].

The occurrence and seasonal changes of antibiotics in the Victoria Harbour and the Pearl River were studied using high-performance liquid chromatography-electrospray ionization tandem mass spectrometry with multiple reaction monitoring (MRM). The results showed that the concentrations of antibiotics were mainly below the limit of quantification (LOQ) in the ambient marine water of Victoria Harbour. However, except for amoxicillin, all the target antibiotics were detected in the Pearl River during high (summer) and low (early spring) water seasons with the concentrations ranging from 13 to 69 ng x L(-1) and from 70 to 489 ng x L(-1), respectively. The concentrations of antibiotics in the Pearl River are all higher than that in America and other western developed countries, no matter in spring or summer. The concentrations of antibiotics showed sensitive daily changes in the high water season.