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AOX POLLUTION IN the Hangzhou Bay: levels and sources
1  Rui Liu, Yangtze Delta Region Institute of Tsinghua University, Zhejiang. Chuangxin Building 501, Yatai Road 705, Nanhu District, Jiaxing, 314006, China. Email:


Organic halogens were closely watched in the marine for their persistence and ecotoxicological risk. The adsorbable organic halogens (AOX), as a sum indicator for the variety of organic halogens, was studied the concentration in seawater and sediment samples at 12 sites in the Hangzhou Bay (Fig.1). The results showed that the AOX concentrations in the sea water of Hangzhou Bay varied from 140.6±45.6 μg/L to 716.1±62.3 μg/L, much higher than the reported data in many other water bodies (Fig.2). However, the AOX concentration in the sediment of the Hangzhou Bay was relatively low, only 11.3±2.4 to 112.7±7.2 mg/kg, as probably resulted from the influence of the Yangtze River. Eleven WWTPs, the capacity of which covered 64.7% of the total capacity of all 141 WWTPs around the Hangzhou Bay, were with annually discharged amount of no more than 3.2% of the AOX concentration in the Hangzhou Bay. However, their impact was still inneglectible considering the accumulative and refractory nature of the AOX compounds.

The AOX in the Hangzhou Bay was predominantly artificial rather than nature produced. It was reported that naturally produced AOX significantly dependent on water quality indicators such as pH, Cl- and TOC, while the above correlation could be broken when suffered the artificial wastewater. The Pearson correlation coefficients r in the seawater of the Hangzhou Bay were 0.190 (p=0.553), -0.423 (p=0.170), -0.222 (p=0.487) and -0.540 (p=0.07) between AOX and COD, pH, salinity and TOC, respectively, all insignificant at 5% level. In addition, the AOX /TOC ratio in the seawater of the Hangzhou Bay varied from 21.7 to 628.2 g/kg, one order of magnitude higher than those reported in literature.

Keywords: Adsorbable organic halogens (AOX) pollution ; Hangzhou Bay;Levels; Sources