Concentration level and geographical distribution of nitrobenzene in Chinese surface waters.
Nitrobenzene was reported to occur at relatively high concentrations in some Chinese surface water and to cause an environmental pollution event in 2005. To map the distribution of nitrobenzene in the Chinese surface water throughout China, surface water samples were collected from over 600 sites in the 7 major watersheds and three drainage areas. The samples were analyzed for concentration of nitrobenzene. Overall, nitrobenzene was more frequently detected at higher concentrations in the rivers of North China, including Songhua River, Liaohe River, Haihe River, Yellow River, Huaihe River, and Northwest drainage area rivers, compared with those in the rivers of South China, including Yangtze River, Pearl River, Southeast drainage area rivers and Southwest drainage rivers. The detection rate of nitrobenzene was 83.2% for all the samples, with a mean value of 18.1 ng/L and a range of < 0.3-8450.0 ng/L. The highest mean concentration of nitrobenzene was observed in the Yellow River, followed by Huaihe River. The results of this investigation indicated that nitrobenzene should be of particular concern in China and its ecological and health risk should be assessed.