Spatial distribution and deposition history of nonylphenol and bisphenol A in sediments from the Changjiang River (Yangtze River) Estuary and its adjacent East China Sea

Nonylphenol (NP) and bisphenol A (BPA) are endocrine disruptors causing harmful effects including feminization and carcinogenesis to various organisms, and consequently, their contamination in natural environment has received wide concerns. This study reports the distribution characteristics of NP and BPA in surface sediments and their deposition history based on a dated sediment core in the Changjiang River (Yangtze River) Estuary and its adjacent East China Sea. The contents of NP and BPA in surface sediments ranged from 1.56-35.8 and 0.72-13.2 ng/g (dry mass), respectively, with high values recorded in the two mud zones, the Changjiang River Estuarine Mud Zone and the Zhejiang Coastal Mud Zone. High values in the Zhejiang Coastal Mud Zone suggest the possibility of long distance transport of both contaminants through the Changjiang riverine plume. The contents were not correlated with the distance from the pollution source, indicating other factors including particle deposition rate and sediment grain size obviously affecting the distribution pattern. NP was also detected in a sediment core at layers deposited from the year of 1971 to 2001 with contents of up to 20.9 ng/g (dry mass). The deposition fluxes of NP varied from 0.68 to 17.9 ng/(cm²·a) with peaks and valleys reflecting the traces of economic development history in China during the previous three decades. BPA was detected at sediment layers deposited from 1973 to 2001 with contents of up to 3.66 ng/g. The fluxes of BPA varied from 0.62 to 3.13 ng/(cm²·a) showing a similar pattern as NP. The contents of NP and BPA also indicated potential risks on benthic organisms in the study area.