Multi-criteria ranking and receptor modelling of airborne fine particles at three sites in the Pearl River Delta region of China

The multi-criteria decision making methods, Preference METHods for Enrichment Evaluation (PROMETHEE) and Graphical Analysis for Interactive Assistance (GAIA), and the two-way Positive Matrix Factorization (PMF) receptor model were applied to airborne fine particle compositional data collected at three sites in Hong Kong during two monitoring campaigns held from November 2000 to October 2001 and November 2004 to October 2005. PROMETHEE/GAIA indicated that the three sites were worse during the later monitoring campaign, and that the order of the air quality at the sites during each campaign was: rural site > urban site > roadside site. The PMF analysis on the other hand, identified 6 common sources at all of the sites (diesel vehicle, fresh sea salt, secondary sulphate, soil, aged sea salt and oil combustion) which accounted for approximately 68.8 ± 8.7% of the fine particle mass at the sites. In addition, road dust, gasoline vehicle, biomass burning, secondary nitrate, and metal processing were identified at some of the sites. Secondary sulphate was found to be the highest contributor to the fine particle mass at the rural and urban sites with vehicle emission as a high contributor to the roadside site. The PMF results are broadly similar to those obtained in a previous analysis by PCA/APCS. However, the PMF analysis resolved more factors at each site than the PCA/APCS. In addition, the study demonstrated that combined results from multi-criteria decision making analysis and receptor modelling can provide more detailed information that can be used to formulate the scientific basis for mitigating air pollution in the region.

Multifractal analyses of daily rainfall time series in Pearl River basin of China

The multifractal properties of daily rainfall time series at the stations in Pearl River basin of China over periods of up to 45 years are examined using the universal multifractal approach based on the multiplicative cascade model and the multifractal detrended fluctuation analysis (MF-DFA). The results from these two kinds of multifractal analyses show that the daily rainfall time series in this basin have multifractal behavior in two different time scale ranges. It is found that the empirical multifractal moment function K(q)K(q) of the daily rainfall time series can be fitted very well by the universal multifractal model (UMM). The estimated values of the conservation parameter HH from UMM for these daily rainfall data are close to zero indicating that they correspond to conserved fields. After removing the seasonal trend in the rainfall data, the estimated values of the exponent h(2)h(2) from MF-DFA indicate that the daily rainfall time series in Pearl River basin exhibit no long-term correlations. It is also found that K(2)K(2) and elevation series are negatively correlated. It shows a relationship between topography and rainfall variability.

Acoustic Observation of the Spawning Aggregation of Megalobrama hoffmanni in the Pearl River

Using the Simrad EY60 split-beam echosounder, the spawning aggregation of Megalobrama hoffmanni was observed at the Luopang spawning grounds in the Pearl River, China, from April 19 to 22 2006. With the boat anchored, the transducer was stationary and was aimed horizontally to monitor the migration of the fish. Using fishery information, the echoes of M. hoffmanni were identified. The results showed that the spawning aggregation of M. hoffmanni at Luopang was obvious and easy to discriminate. The target strength of M hoffmanni in situ ranged from -33.8 dB to -52.3 dB (average 42.2dB). The aggregation of M. hoffmanni was obviously affected by light. With a speed of -0.31 m/s, 88.9% of the spawning stocks migrated upstream. Most M hoffmanni were recorded moving near the bottom. Their distinctive acoustic signature demonstrated the suitability of the stationary acoustic observation for M. hoffmanni identification and discrimination.

Metzia longinasus, a new cyprinid species (Teleostei: Cypriniformes) from the Pearl River drainage in Guangxi Province, South China

Metzia longinasus, a new cultrine cyprinid species from the Hongshui-He River of the Pearl River drainage in Guangxi Province, southern China, is described here. It can be distinguished from all other congeners by having a combination of the following characters: a superior mouth, 43 or 44 lateral-line scales, a long head (length 27.2-30.8% of standard length), a long snout (length 31.7-37.0% of head length), 10 or 11 branched anal-fin rays, and no longitudinal black band extending along each side of body from the extremity of the gill opening to caudal-fin base.

Perfluorinated compounds in the Pearl River and Yangtze River of China

A total of 14 perfluorinated compounds (PFCs) were quantified in river water samples collected from tributaries of the Pearl River (Guangzhou Province, south China) and the Yangtze River (central China). Among the PFCs analyzed, perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) were the two compounds with the highest concentrations. PFOS concentrations ranged from 0.90 to 99 ng/1 and < 0.01-14 ng/1 in samples from the Pearl River and Yangtze River, respectively; whereas those for PFOA ranged from 0.85 to 13 ng/l and 2.0-260 ng/l. Lower concentrations were measured for perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS), perfluorooctanesulfoamide (PFOSA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorononaoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUnDA). Concentrations of several perfluorocarboxylic acids, including perfluorododecanoic acid (PFDoDA), perfluorotetradecanoic acid (PFTeDA), perfluorohexadecanoic acid (PFHxDA) and perfluorooctadecanoic acid (PFOcDA) were lower than the limits of quantification in all the samples analyzed. The highest concentrations of most PFCs were observed in water samples from the Yangtze River near Shanghai, the major industrial and financial centre in China. In addition, sampling locations in the lower reaches of the Yangtze River with a reduced flow rate might serve as a final sink for contaminants from the upstream river runoffs. Generally, PFOS was the dominant PFC found in samples from the Pearl River, while PFOA was the predominant PFC in water from the Yangtze River. Specifically, a considerable amount of PFBS (22.9-26.1% of total PFC analyzed) was measured in water collected near Nanjing, which indicates the presence of potential sources of PFBS in this part of China. Completely different PFC composition profiles were observed for samples from the Pearl River and the Yangtze River. This indicates the presence of dissimilar sources in these two regions. (c) 2007 Elsevier Ltd. All rights reserved.

Acid volatile sulfide and simultaneously extracted metals in the sediment cores of the Pearl River Estuary, South China

The acid-volatile sulfide (AVS), simultaneously extracted metals (SEM), total metals, and chemical partitioning in the sediment cores of the Pearl River Estuary (PRE) were studied. The concentrations of total metals, AVS, and SEM in the sediment cores were generally low in the river outlet area, increased along the seaward direction, and decreased again at the seaward boundary of the estuary. The amounts of AVS were generally greater in deeper sediments than in surface sediments. SEM/AVS was > 1 in the surface sediments and in the river outlet cores. The ratio was < 1 in the sediments down the profiles, suggesting that AVS might play a major role in binding heavy metals in the deep sediments of the PRE. The SEM may contain different chemical forms of trace metals in the sediments, depending on the metal reaction with 1 M cold HCl in the AVS procedure compared with the results of the sequential chemical extraction. The SEM/AVS ratio prediction may overestimate trace metal availability even in the sediments with high AVS concentrations. (c) 2004 Elsevier Inc. All rights reserved.