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

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.

[Characteristics of Nitrogen and Phosphorus Formation in Atmospheric Deposition in Dianchi Lake and Their Contributions to Lake Loading].

To examine the effects of seasonal changes and precipitation on the concentrations of various nitrogen and phosphorus forms in Dianchi Lake, the concentrations of various nitrogen and phosphorus forms of atmospheric deposition were determined by UV spectrophotometry. Additionally, the contributions of nitrogen and phosphorus to water pollution in Dianchi Lake were discussed. The results showed that the atmospheric depositional nitrogen concentration in Dianchi Lake is generally consistent with the characteristics of the low rainy season and high dry season. The nitrogen and phosphorus load of atmospheric deposition was positively correlated with rainfall. Seasonal changes were mainly characterized by low dry season and high rainy season. The atmospheric depositional nitrogen load was dominated by dissolved inorganic nitrogen, which accounted for 63.70% of the total nitrogen deposition load. The phosphorus load was mainly PP, which accounted for 45.54% of the total phosphorus precipitation load. Excessive fertilization and loss of nitrogen and phosphorus from fertilizers are the major sources of nitrogen and phosphorus in atmospheric wet deposition. Combined with data from rivers entering the lake, the settlements of TN and TP in the atmospheric deposition of Dianchi Lake were 6.14% and 12.76% of the river load, respectively. Therefore, the primary source of pollution in Dianchi Lake was still the load brought by the river into the lake. However, the nitrogen and phosphorus fluxes in the atmospheric deposition of Dianchi Lake were at intermediate levels compared with other regions, so this contribution requires further investigation.

[Occurrence and Ecological Risk Assessment of Typical Persistent Organic Pollutants in Baiyangdian Lake].

A comprehensive survey of the pollution characteristics of persistent organic pollutants (POPs) in the surface water and surface sediment of Baiyangdian Lake was carried out. The survey showed that:① The concentrations of the polycyclic aromatic hydrocarbons(PAHs), organic chlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs) in the surface water of Baiyangdian Lake were 71.32-228.27 ng·L-1, 2.62-6.13 ng·L-1, and 0-6.5 ng·L-1, respectively, and those in the surface sediment were 163.20-861.43 ng·g-1, 2.25-6.07 ng·g-1, and 230.96-1224.13 pg·g-1, respectively. On comparison with historical data, the concentrations of PAHs and OCPs in both the surface water and surface sediment were found to be decreasing, while compared with the domestic and foreign lakes, the concentration of PBDEs in the surface sediment was at a low level. ② The main source of PAHs, both in the surface water and surface sediment in Baiyangdian Lake, originated from fuel discharge and combustion sources. HCHs compose the main part of OCPs in both the surface water (93.76%) and surface sediment (63.10%). In the surface water body, HCHs mainly originated from the degradation of industrial HCHs; in some sites HCHs originated from atmospheric long-distance transmission and the usage of Lindane, while DDTs originated from historical residues. In surface sediment, HCHs mainly originated from the usage of new Lindane, with little industrial HCHs, and DDTs mainly originated from historical residues, while new DDTs may have been used in some sites. BDE-2 (65.80%) composed the main part of PBEDs in the surface water, and it mainly originated from atmospheric long-distance transmission and degradation of high brominated diphenyl ethers; BDE-209 (63.82%) constituted the main part of PBDEs in the surface sediment, and it mainly originated from the commercial Deca-BDEs.③ Ecological Risk Assessment show that there was no obvious ecological risks in Baiyangdian Lake, but in some sites POPs may cause ecological risks; these sites should be monitored more frequently.

[Pollution Characteristics and Health Risk Assessment of Volatile Organic Compounds in Baiyangdian Lake].

In order to survey the present pollution from volatile organic compounds in Baiyangdian Lake, 15 water samples were collected in March 2016, and analyzed for 54 VOCs by purge and trap gas chromatography-mass spectrometry. The distribution characteristics and health risk assessments were investigated, and the pollution from the VOCs was evaluated by a comprehensive pollution index. The survey showed that:① a total of 14 VOCs were detected in Baiyangdian water, with a 100% detection rate for dichloromethane, benzene, toluene, ethylbenzene, xylene, and 1,3,5-trimethylbenzene; xylene had the highest concentration with an average concentration of 564.9 ng ·L-1; and trichloroethylene had the lowest concentration with an average concentration of 3.3 ng ·L-1 and a detection rate of only 13.3%; ② the total concentration of VOCs in Baiyangdian water was between 423.0 and 4207.8 ng ·L-1, and benzene was the main pollutant, with its main source coming from the effluent from the upstream sewage treatment plant, the industrial wastewater, and the exhaust emissions of motor vehicles in the city; and ③the health risk assessment showed that VOCs in Baiyangdian Lake did not produce carcinogenic and non-carcinogenic risks to humans, and the VOC comprehensive pollution index shows that the VOCs in the Baiyangdian Lake were at a clean level.

[Temporal and Spatial Variation Characteristics of Nitrogen and Phosphorus in Sediment Pore Water and Overlying Water of Dianchi Caohai Lake].

The vertical variation in the contents of nitrogen and phosphorus with different forms in pore water and overlying water was continuously measured for twelve months in Dianchi Caohai Lake. The research revealed the difference of N or P concentration between pore water and overlying water and the contribution of nitrogen and phosphorus forms. It is significant to understand the formation of N and P and the ratio of N/P in pore water in the fields of lake eutrophication and the control of internal nutrient-loading. The results demonstrated that:①Sediment pore water ρ(NH4+-N) was significantly higher than that in overlying water. But for NO3--N, it obeyed the opposite rule. From Feb. to Nov., ρ(SRP) was higher than that in overlying water, while the opposite rule was found in Dec. and Jan.. ②In sediment pore water, ρ(NH4+-N) or ρ(SRP) presented the maximum contribution ratio of DTN (78%) or DTP (61%), respectively. While, in overlying water, the maximum contribution ratio was DON(44%) or DOP(81%), respectively. Compared to those in spring and winter, the contribution of ρ(NH4+-N) and ρ(SRP) increased distinctly and the contribution of ρ(NO3--N), ρ(DON) and ρ(DOP) dropped obviously in summer and autumn. ③The temporal variations for the ratios of DTN/DTP, (NH4+-N+NO3--N)/SRP and DON/DOP in pore water were all in the following sequence:spring> winter> summer> autumn. In overlying water, the N/P ratio in spring was relatively higher than that in the other three seasons.