Characteristics of Volatile Organic Compounds Pollution and Risk Assessment of Nansi Lake in Huaihe River Basin

Abstract

This study aimed to investigate the pollution characteristics of the volatile organic compounds in Nansi Lake and evaluate the ecological and health risks. In November 2017, water samples collected from 25 sampling points in Nansi Lake using the purge and trap technique and GC-MS detected 52 types of VOCs. The detection rate of ethylbenzene, m-/p-xylene, o-xylene, 1,2-dichlorobenzene, and naphthalene reached 100%, and cis-1,3-dichloropropene and toluene reached 96%. The detection rate of 1,2,4-trimethyl benzene was the lowest, at only 12%, the average concentration of 1,2-dichlorobenzene was the highest, reaching 3.49 μg·L-1, and 1,2,4-trimethyl benzene was only 0.02 μg·L-1. The concentration of 1,2-dichlorobenzene in Nansi Lake was generally higher than that of other VOCs. Meanwhile, the concentrations of m-/p-xylene and ethylbenzene at point NSH-24 far exceeded the other VOCs, but the median value of all VOCs did not exceed 4 μg·L-1. The spatial distribution of the VOCs concentrations in Nansi Lake presented high values in the northwest and southeast, and low in the middle. The leading cause of VOCs pollution in Nansi Lake may be the exhaust gas emitted by shipping vessels during navigation, and the secondary cause is the collection of VOCs in the upstream and downstream tributaries and the influence of human factors. The health risk assessment of Nansi Lake found that, overall, there was no carcinogenic or non-carcinogenic health risk, but the risk value of individual points was relatively high, even exceeding the risk threshold set by the US EPA. There were 12 points in Nansi Lake where the ecological risk quotient exceeded 1, indicating an ecological risk to aquatic organisms.