Organic micropollutants in the Yangtze River: Seasonal occurrence and annual loads

Abstract

• The Yangtze River drains 40% of China's mainland with 400 million inhabitants • Monthly concentrations and annual loads of organic pollutants were determined • Seasonality of loads of PAHs, most pesticides, and antiinfectives were concise • In spite of low concentrations due to high water discharge, pollutant loads are considerable a b s t r a c t a r t i c l e i n f o Twenty percent of the water run-off from China's land surface drains into the Yangtze River and carries the sewage of approximately 400 million people out to sea. The lower stretch of the Yangtze therefore offers the opportunity to assess the pollutant discharge of a huge population. To establish a comprehensive assessment of micropollutants, river water samples were collected monthly from May 2009 to June 2010 along a crosssection at the lowermost hydrological station of the Yangtze River not influenced by the tide (Datong Station, Anhui province). Following a prescreening of 268 target compounds, we examined the occurrence, seasonal variation, and annual loads of 117 organic micropollutants, including 51 pesticides, 43 pharmaceuticals, 7 household and industrial chemicals, and 16 polycyclic aromatic hydrocarbons (PAHs). During the 14-month study, the maximum concentrations of particulate PAHs (1-5 μg/g), pesticides (11-284 ng/L), pharmaceuticals (5-224 ng/L), and household and industrial chemicals (4-430 ng/L) were generally lower than in other Chinese rivers due to the dilution caused of the Yangtze River's average water discharge of approximately 30,000 m 3 /s. The loads of most pesticides, anti-infectives, and PAHs were higher in the wet season compared to the dry season, which was attributed to the increased agricultural application of chemicals in the summer, an elevated water discharge through the sewer systems and wastewater treatment plants (WWTP) as a result of high hydraulic loads and the related lower treatment efficiency, and seasonally increased deposition from the atmosphere and runoff from the catchment. The estimated annual load of PAHs in the river accounted for some 4% of the total emission of PAHs in the whole Yangtze Basin. Furthermore, by using sucralose as a tracer for domestic wastewater, we estimate a daily disposal of approximately 47 million m 3 of sewage into the river, corresponding to 1.8% of its average hydraulic load. In summary, the annual amounts flushed by the Yangtze River into the East China Sea were 2.9 × 10 6 tons of dissolved and particulate organic carbon (DOC and POC), 369 tons of PAHs, 98 tons of pesticides, 152 tons of pharmaceuticals, and 273 tons of household and industrial chemicals. While the concentrations seem comparably moderate, the pollutant loads are considerable and pose an increasing burden to the health of the marine coastal ecosystem.

Depth profile of persistent and emerging organic pollutants upstream of the Three Gorges Dam gathered in 2012/2013

“…High dilution and fast metabolism of these compounds in the environment may explain the lower concentrations observed in surface water. All other pharmaceutical active compounds observed in this study have already been reported either in surface waters or in the influent/effluent of wastewater treatment plants in China (Bu et al 2013;Heeb et al 2012;Liu and Wong 2013;Qi et al 2014). Values for carbamazepine and diclofenac which were determined in this study with higher mean abundance have been reported in surface water in China with concentration ranges from nondetection to 675 and nondetection to 843 ng L −1 , respectively (Bu et al 2013).…”

“…Pharmaceuticals were detected between 2009 and 2010 near Datong (600 km from the East China Sea) at concentrations usually below 50 ng L −1 . Furthermore, other household chemicals were detected, especially the sweetener sucralose which occurred at an average concentration of 217 ng L −1 (Qi et al 2014). The distribution pattern of PPCPs within the TGR is comparable to PFCs which are emitted by point sources.…”

“…We already demonstrated in our recent study that low concentrations of polycyclic aromatic hydrocarbons (PAHs) in the reservoir correspond to high total mass fluxes in the large water body (Deyerling et al 2014). Qi et al applied this principle (among other analytes) on PPCPs (Qi et al 2014). We applied our method for determination of a depth profile at Maoping in front of the Three Gorges Dam (TGD) by sampling in three different water depths for investigating the homogeneity of the water body.…”

“…Pharmaceuticals and personal care products (PPCPs) found as ubiquitous residues in the aquatic environment have drawn increasing attention over the last years (Campbell et al 2006;Daughton 2004;Qi et al 2014). The broad application of these chemicals in daily life and high prescription numbers of pharmaceuticals lead to a high burden of nonmetabolized PPCPs in wastewater treatment plants, where many of them show high persistence (Müller et al 2011;Wode et al 2012).…”

“…Thus, typically, the influents and effluents of wastewater treatment plants were targets of deeper investigation (Chang et al 2010;Duan et al 2013;Gao et al 2012;Yan et al 2014). Depending on the type and location of sampling as well as on stability of the single compounds, the detected concentrations vary over a large scale (approximately between lower micrograms per liter and lower nanograms per liter scale) (Chang et al 2010;Qi et al 2014;Wolf et al 2013;Yan et al 2014).…”