Abstract: To identify the major pollutants in the surface waters along the riverbank of the Yangtze River middle mainstream and explore their temporal and spatial distribution, we conducted a survey on five typical types of riverbanks which have been exploited for agriculture and fishery, industrial production, port logistics, river crossing transportation, and urban living. We selected Yichang, Wuhan, and Huangshi in the middle mainstream of the Yangtze River as three representative segments. According to the Environmental Quality Standard for Surface Water (GB 3838—2002) and the Standard for Drinking Water Quality (GB 5749—2006), we found that the main pollutants were total nitrogen (TN), total phosphorus (TP), ammonia nitrogen (NH₃-N), iron (Fe) and manganese (Mn). All the monitored pollutants presented a similar pattern of spatial variation, with the lowest annual mean concentration in Wuhan and the highest in Yichang. However, the temporal variations in conventional pollutants and heavy metals were different. For the conventional pollutants, the lowest mean concentration was found in summer while the highest value was in autumn. For heavy metals, the relatively higher concentrations were observed in autumn and winter, whereas the lower value was in spring. Along the middle mainstream of the Yangtze River, the riverbank exploited for urban living suffered from the most severe pollution, with annual mean concentrations of TN, TP, NH₃-N, Fe and Mn across the three segments amounting to 11.58, 0.83, 5.83 mg/L, 351.67 , 147.66 μ g/L respectively, which exceeded the standard by 11.58, 4.15, 5.85, 1.17, and 1.48 folds. A total of 8 kinds of pyrethroid pesticides, 33 kinds of organophosphorus pesticides and 12 kinds of organochlorine pesticides were detected in the surface water along the agriculture and fishery riverbank. Besides, 13 polycyclic aromatic hydrocarbons (PAHs) were detected along the riverbank exploited for industrial production, with tetramethrin, tetraethyl pyrophosphate (TEPP), 4.4′- dichlorodiphenyltrichloroethane (DDT), and indeno (1, 2, 3-cd) pyrene as the major compositions, yet all lower than standard. The results of sources apportionment of PAHs showed that the PAHs stemmed from wood, coal and a small amount of oil. These research findings would contribute to the rational development and structural optimization of riverbanks, and better protecting the Yangtze River with providing useful data.

Key words: mainstream of the Yangtze River, riverbank type, pollutants, heavy metal, pesticide, polycyclic aromatic hydrocarbons, Yangtze River Protection