Pollutant transport in the world’s third longest river

The Yangtze river (Source: http://www.britannica.com/EBchecked/topic/651857/Yangtze-River)
The Yangtze river (Source: http://www.britannica.com/EBchecked/topic/651857/Yangtze-River)

For the past year, VTSuN has had the pleasure to host Dr. Yi Yang. She is a professor at East China Normal University in Shanghai, China and she is spending a 2-year sabbatical at Virginia Tech, working in Dr. Michael Hochella’s group and CEINT, the Center for the Environmental Implications for Nanotechnology.

A collaboration between Dr. Hochella’s group at Virginia Tech and Dr. Yang own group at East China Normal University brought new understanding on the transport of emerging organic contaminants in the Yangtze River estuary (near Shanghai, China) and adjacent East China Sea coastal areas.

For an environmental engineer or scientist, the Yangtze is is an incredibly interesting river. With a length of 3,915 miles (6,300 kilometers), it is the longest river in Asia and the third longest in the world, only shorter than the Nile and the Amazon rivers. In fact, the Yangtze is only 59 miles shorter than the Amazon. The Yangtze has a few special characteristics that are not shared with their top-3 podium counterparts:

First, although the Nile and the Amazon flow through many countries, the Yangtze is a one-country guy, flowing only through China.

Second, although the Nile and the Amazon are also top-3 in terms of drainage area, the Yangtze is not even top-10. It drains an area of 1,800,000 km², 4 times smaller than the Amazon’s 7,050,000 km².

Third, although the Yangtze basin area is 4 times smaller than the Amazon’s, it is home to one third of China’s population (roughly 452 million people!), versus only the Amazon’s 10 million people.

The Yangtze River
The Yangtze River

We can expect the presence of over 450 million people centered around a relatively small area drained by one single river to heavily affect the presence, concentration, and transport of pollutants in this river and subsequently in the estuary and the ocean and thus we can’t help but be extremely curious about what’s going on there.

Dr. Yang’s and Dr. Hochella’s groups investigated the presence and distribution of 42 emerging organic compounds (EOCs) in the Yangtze River Estuary and adjacent East China Sea coastal areas. The EOCs studied were mainly pharmaceuticals, including antibiotics, hormones and sterols, and also two industrial endocrine disruptors. These pharmaceuticals are organic components commonly found in personal care products, food additives, medications, etc. In this work, the EOCs we found to be associated with colloids, which are small, 1-1000 nm particles, suspended in the river water. Colloids can be nano-sized or larger. They can be man-made but are more commonly naturally occurring in rivers. Physical-chemical properties of these colloids, including their size, surface charge, and chemical composition, were found to be the main factors controlling their association to EOCs. Moreover, these colloidal properties were all significantly related to salinity, indicating the critical role played by increasing salinity in EOCs-colloid interaction in an estuarine system, as the Yangtze river reaches the East China Sea in Shanghai. This work provided significant data for understanding the interaction between EOCs and colloids in a highly complex estuarine aquatic environment.

For more information on this study, please read their recently published paper:

Yan, C.X., Yang, Y.*, Zhou, J.L., Nei, M.H., Liu, M., Hochella Jr., M.F. (2015) Selected emerging organic contaminants in the Yangtze Estuary,China: A comprehensive treatment of their association with aquatic colloids. Journal of Hazardous Materials. 283: 14-23. 


About the Author:  Marina Vance is the Associate Director for VTSuN: Virginia Tech’s Center for Sustainable Nanotechnology and a research scientist of the Institute for Critical Technology and Applied Science (ICTAS) at Virginia Tech.

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