[Fluorescence Spectral Characteristics of Dissolved Organic Matter in Songhua Lake Sediment].

Dissolved organic matter (DOM) has a significant impact on the main pollution indicators of the lake (e.g., COD), and sediment is the main source of pollution in the lake. Research on the fluorescence spectral characteristics of DOM in sediments is important to reveal the mechanism of lake pollution. In this study, sediments were collected from 20 sites in Songhua Lake. The DOM components in the sediment were analyzed using the excitation emission matrix-parallel factor analysis (EEM-PARAFAC) technique, and the properties of the sediment DOM were clarified via spectroscopy. Additionally, the relationship between DOM and eutrophication of the water column was explored. The results showed that four components were identified from the sediment DOM of Songhua Lake:humic-like C1 (330/415 nm), C2 (255/440 nm), C3 (365/470 nm), and protein-like C4 (280/355 nm). The high HIX and low BIX indicated that the source of sediment DOM was mainly terrestrial and included some biological sources. The spatial distribution of the fluorescence intensity of the four components was relatively similar, showing that the fluorescence intensity was higher in the upstream (S1-S7) than that in the downstream (S8-S20). The massive deposition of suspended particulate matter (SPM) carried by the three rivers (Huifa River, Songhua River, and Jiao River) was the main reason for this spatial distribution. Eutrophication status in the water column of Songhua Lake was similar to the fluorescence intensity distribution of sediment DOM. Meanwhile, there was a strong correlation between eutrophication level and sediment DOM fluorescence intensity in the downstream water column of Songhua Lake.

[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 and Ecological Risk Assessment of POPs Pollution in Sediments of Xiaoxingkai Lake in the Northeast China].

The pollution characteristics of polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), and phthalate esters (PAEs) in the surface sediments of Xiaoxingkai Lake were analyzed by GC-MS, and the main sources and biological toxicity risks of the pollutants were discussed. The results show that:① The content of PAHs in the sediments of xiaoxingkai lake ranged from 82.1 to 534.6 ng·g-1, and the concentration of PAHs in the northwestern port of the lake was higher. The content of OCPs and PAEs in the sediments ranged from 4.8 to 50.4 ng·g-1 and 33.3 to 401.6 ng·g-1, respectively. The concentration was higher in the southeastern lakes. ② PAHs in the sediments were dominated by 3-5-ring compounds (accounting for more than 85%), which were mainly combustion sources, among which the combustion of coal and firewood contributed 47%, the combustion of gasoline and diesel contributed 39%, and the oil product leakage contributed 14%. The OCPs were mainly HCHs (78%) from the use of new lindane and the input of a small amount of industrial HCHs. The PAEs were mainly dibutyl phthalate (DBP) and diethyl phthalate (2-ethyl hexyl) ester (DEHP; 94%), which were mainly derived from household garbage and common human articles. ③ Compared with other lakes in China, PAHs and PAEs in the sediments of Xiaoxingkai Lake are at a low pollution level, and there is no ecological risk at present, but some OCPs at some points present a moderate ecological risk.

[PAHs Pollution Characteristics and Source Analysis of Typical Lake and Reservoir Sediments in Jin-Ji-Liao Area].

In this research, 29 surface sediments samples of three typical lake reservoirs (in Yuqiao Reservoir, Hengshui Lake, and Dahuofang Reservoir) in the Jin-Ji-Liao area were collected and investigated, and the contents of 16 polycyclic aromatic hydrocarbons were detected using GC-MS. The results show that the Sigma PAHs (ng·g-1) in the sediments were 337.3-1604.1 (mean value 820.0), 461.1-1497.5 (mean value 932.3), and 102.3-2240.5 (mean value 564.9), respectively. Compared with other domestic rivers and lakes, the pollution levels of the PAHs in the three typical lakes were all at a medium level. The three lakes and reservoirs had consistency in the ratio of the number of rings, which is primarily high. PAHs source analyses were carried out by the characteristic ratio and primary component analysis method, and the results show that three lakes reservoirs pollution were caused mostly by combustion sources (including petroleum, coal, and biomass combustion), with a few petroleum sources. Additionally, the pollution contribution ratio of incomplete combustion of gasoline and diesel oil was 51.4%, and the pollution contribution ratio of combustion of coal and firewood were 22.3%. The risk evaluation results indicate that PAHs in the surface sediments of Yuqiao Reservoir, Hengshui Lake, and Dahuofang Reservoir are generally at a medium and low level, but the monitoring of three types of substances, Flu, InP, and DahA, should be strengthened, and corresponding emergency measures should be taken.