Identification and ranking of the risky organic contaminants in the source water of the Danjiangkou reservoir

Abstract

The Danjiangkou reservoir was selected to provide the source water for the middle routes of the South to North Water Transfer Project, which has provoked many environmental concerns. To date, investigations of water contamination of the source water of the Danjiangkou reservoir with organic micro-pollutants have been limited. This study was conducted to identify and rank organic contaminants that pose risks in the Danjiangkou reservoir. To this end, the Chemical Hazard Evaluation and Management Strategies (CHEMS-1) approach was adapted to integrate the deconvolution technology of qualitative identifying contaminants for site-specific environmental matrices. The samples were screened for the presence of 1093 contaminants using deconvolution technologies and the hazard values of the identified contaminants were calculated using the adapted CHEMS-1 approach according to their hazardous properties and occurrence in source water. The results showed that 46 contaminants from 1093 targets were present in Danjiangkou water, 23 of which appeared at frequencies higher than 50%, and 15 of which were identified as priorities. Over half (53%) of the highranked contaminants were polycyclic aromatic hydrocarbons (PAHs), with chrysene ranked highest on the list. Health risk assessment of the top-ranked PAHs was conducted and revealed that cancer risks of PAHs detected in the source water of Danjiangkou to different populations ranged from 10 -7 to 10 -6, indicating a low cancer risk to consumers. The results of this study indicated that the adapted CHEMS-1 approach was feasible for site-specific screening of organic contaminants to identify and rank potential priority pollutants.

Screening for over 1000 organic micropollutants in surface water and sediments in the Liaohe River watershed

“…A total of 81 OMs belonging to 23 chemical classes were identified at least once in surface water, 18 of which were detected at frequencies over 50%. This number of detection was larger than those (46 OMs in 17 chemical classes) detected in the Danjiangkou reservoir using the same method (Bu et al, 2014a), as the Danjiangkou reservoir was designated as a drinking water source by strict protection. Great variety of OMs was identified from samples extracted from sampling sites, including pesticides and their metabolites, intermediates in organic synthesis, pharmaceuticals and personal care products.…”

“…The analytical procedures for surface water samples were performed according to Bu et al (2014a) and Zhong et al (2010). Briefly, two liter of water was extracted by solid phase extraction with C18 (500 mg, 6 ml; Supelco, Bellefonte, PA, USA) coupled with Oasis Ò hydrophilic-lipophilic balance (HLB, 500 mg, 6 ml; Waters, Milford, MA, USA) cartridges.…”

“…Data acquisition and processing were based on retention time locking and deconvolution technologies, which was accessed in ChemStation Software (version E.0200.493; Agilent Technologies, USA). One complete run lasted 48 min, details of the GC-MSD method was described in previous studies (Bu et al, 2014b;Bu et al, 2014a).…”

“…terbucarb, Tables S4 and S5). Terbucarb is a frequently detected contaminant in China in our previous studies for sediments in Haihe River watershed (Bu et al, 2014b) and surface water in Danjiangkou reservoir (Bu et al, 2014a). Terbucarb is used as an insecticide and an herbicide Table 2 Comparison of concentrations of PAHs in surface water and sediment from different studies.…”

“…In our previous study, a method for screening 50 phenols in water was established and applied in the case of Taihu Lake (Zhong et al, 2010). Further, this method was modified for qualitative screening of 1093 OMs in water of the Danjiangkou reservoir (Bu et al, 2014a). More recently, we introduced a set of quantification internal standards (QISs) to improve the quantification ability of the method, and results showed that the high throughout semi-quantification method was feasible for comprehensive analysis of OMs in sediments quantitatively (Bu et al, 2014b).…”