Natural Estrogens in the Surface Water of Shenzhen and the Sewage Discharge of Hong Kong

ABSTRACT

Despite the fact that estrogens cause hormonal disturbances in aquatic organisms, few studies on the estrogen contamination in our surface waters have been conducted. This study was thus conducted (1) to investigate the level of estrogens in the surface waters in Shenzhen and (2) to examine the estrogen levels in the sewage discharges in Hong Kong. Total estrogens (estrone E1, estradiol E2, and estriol E3) in the samples taken from two reservoirs, five rivers, and thirty sampling locations of the seawater in Shenzhen were measured by using ELISA kits. The preliminary results have revealed that the level of estrogens in the surface waters of Shenzhen is generally higher than that in the similar water bodies in well-developed nations. Sewage could be the major source of the estrogen contamination in these waters. The total estrogens levels in the Xili and Shenzhen Reservoirs were in a range of 3–11 ng/L with a mean value of 7 ng/L, where that in four rivers in Shenzhen were found to be 47–90 ng/L and 60.25 ng/L, respectively. In the seawater near the sewage discharge points they were 260–300 ng/L and 287 ng/L, respectively. The estradiol levels in the influent and effluent of three sewage treatment works (STWs) in Hong Kong were also monitored. The activated sludge process used in these STWs removed more than 80% whereas the chemical coagulation processed used at the Stonecutters Island STW removed less estrogens. Biological treatment appears to play a significant role in removing estrogens from wastewater.

Key Words:

• activated sludge
• estrogens
• sewage treatment works
• sewage discharge
• surface waters
• wastewater.

ACKNOWLEDGMENTS

Financial support for this work was provided by a Faculty Research Grant from the Hong Kong University of Science and Technology. Cooperation by the Shenzhen Entry-Exit Inspection and Quarantine Bureau of P. R. China and Environmental Protection Bureau of Nanshan District, Shenzhen, is gratefully acknowledged. We also greatly appreciate Takeda Chemical Industries Ltd for offering us free ELISA kits for the analysis. Last but not least, we also thank the cooperation of the Shatin, Shek Wu Hui, and Stonecutters Island STWs in Hong Kong for allowing us to collect sewage samples.