[Distribution Characteristics and Source Identification of Organochlorine Pesticides in Surface Soil in Karst Underground River Basin].

Six typical surface soil samples were taken in Laolongdong underground river basin, and 20 OCPs were analyzed by gas chromatography equipped with micro-6³Ni electron capture detector. The purpose of this study was to investigate the distribution, composition and source of organochlorine pesticides ( OCPs) in the surface soil of Laolongdong underground river basin, and to further evaluate the pollution level. The results showed that 20 OCPs were inordinately detected in the soil samples and the detection rate of 16 OCPs (except for p,p'-DDE, cis-Chlordane, trans-Chlordane, dieldrin) was 100%. Moreover, the CHLs and DDTs were the main contaminants, and there were obvious differences in the concentrations of organochlorine pesticides between different sampling points. The concentration range of total OCPs was 5.57-2,618.57 ng · g⁻¹ with a mean of 467.28 ng · g⁻¹. Compared with other regions both at home and abroad, the concentrations of HCHs and DDTs in the surface soil samples of the studied area were arranged from high to middle levels. The total concentrations of OCPs, HCHs, DDTs and CHLs had a similar variation tendency in spatial distribution, upstream > midstream > downstream, and the concentrations of OCPs in upstream were obviously higher than those in midstream and downstream. Source analysis indicated that the HCHs mainly came from the use of lindane. DDTs in soil came from not only the early residues but also recently illegal use of industrial DDTs and the input of dicofol. In addition, chlordan was mainly from the early residues and atmospheric deposition. Compared with the Environmental Quality Standard for Soils of China and Netherlands, the level of OCPs in Xinli vilage soil was categorized as highly polluted, but the levels of OCPs in Longjing bay, Xia spit, and Zhao courtyard soils were classified as slightly polluted, while the Longjing adjacency and gaozhong temple soils belonged to unpolluted ones.

[Distribution Characteristics and Source Identification of Polycyclic Aromatic Hydrocarbons, Fatty Acids in Water of Karst Underground River].

In order to explore the contents, composition, distribution characteristics, sources and pollution level of polycyclic aromatic hydrocarbons(PAHs) and fatty acids in water of Qingmuguan karst underground river in Chongqing, water samples were respectively collected from underground river in rainy season and dry season, 2013 and polycyclic aromatic hydrocarbons, fatty acids of the water samples were quantitatively analyzed by Gas Chromatography-Mass Spectrometer(GC-MS). The results showed that the contents of PAHs and fatty acids in water of Qingmuguan karst underground river ranged from 77.3 to 702ng·L-1 and 3302 to 45254 ng·L-1, respectively. In terms of composition, the PAHs profiles were dominated by (2-3) rings PAHs in water samples, which accounted for more than 90% of the total PAHs contents, while the carbon numbers of fatty acids ranged from C10 to C28, and fatty acids profiles were dominated by saturated straight chain fatty acids, followed by mono-unsaturated fatty acids. In terms of the distribution characteristics, the contents of PAHs had minor difference at each sample point in water of underground river in rainy season. At the entrance, exposed and exits, the contents of fatty acids reduced in turn, moreover the contents of fatty acids were close at the exposed and exits. dry season:at the entrance, exposed and exits, the contents of PAHs in water of underground river decreased firstly and then increased. The contents of fatty acids were close at each sample point in water of underground river. As a whole, the contents of PAHs and fatty acids in water of underground river in rainy season were significantly higher than those in dry season. Source analysis indicated that the PAHs in water of Qingmuguan underground river were mainly originated from the combustion of coal and biomass (wood, crop straw, etc) at the underground river catchment. The fatty acids were mainly originated from aquatic algae (diatoms and green alga, etc), and bacteria, with the contribution of aquatic algae dominated. The water of underground river was suffered the middle to mild pollution by PAHs, and compared with the dry season, the rainy season was more severely polluted.

[Impacts of Land Use on the Source of Dissolved Fatty Acids in Epikarst Spring During Rainy Season].

Fatty acids were quantitatively analyzed by gas chromatography-mass spectrometer (GC-MS). Dissolved fatty acids were collected from Nanchuan epikarst spring. The results of BQ, LQ, HQ showed that the average contents of fatty acids were 14870, 12912 and 8801 ng·L-1 from May to July, respectively, and followed the order of SFA> MUFA> BrFA> PUFA. The monomers with highest content were C16:0 and C18:0. From May to July, the fatty acid content increased in BQ , LQ, HQ. The differences in vegetation coverage and bedrock bare rate, as well as the interaction of the dilution effect and soil transfer increase, led to the changes in content and the composition of the fatty acids. Based on the molecular characteristic indices of fatty acids, like H/L, CPIh, TARFA about BQ, LQ, HQ, and contents of fatty acids which were mainly originated from bacteria, phytoplankton or terrigenous higher plant, it was indicated that fatty acids were mainly originated from higher plant in LQ in May, from phytoplankton input in HQ in July, while from bacteria in the other months in LQ, HQ and from May to July in BQ.

[Distribution Characteristics and Source Identification of Organochlorine Pesticides in the Karst Groundwater System].

Chongqing Laolongdong and Qingmuguan karst underground rivers were selected as the research objects, and 21 kinds of OCPs in those two underground rivers were analyzed by gas chromatography (GC-µECD). The results showed that, o,p'-DDE,p,p'-DDE, o,p'-DDD were not detected in Nanshan and Qingmuguan underground rivers; o,p'-DDT and dieldrin were not detected in Qingmugang; but the detection rate of the rest of the OCPs in those two underground rivers was as high as 100%. HCHs and ALDs were the most dominant compounds in Laolongdong underground river, whereas HCHs and methoxychlor were the most dominant compounds in Qingmuguan. The concentration range of total OCPs in Qingmuguan was 145-278 ng·L-1 with a mean value of 213 ng·L-1. The concentration range of total OCPs in Laolongdong was 17.7-40.8 ng·L-1 with a mean value of 32.7 ng·L-1. The OCPs component showed an increasing trend from the entrance to the exit of those two underground rivers. By analyzing the source of OCPs pollution, DDTs in the two underground river basin came from the historical industrial DDTs input; chlordane mainly came from atmospheric deposition. HCHs was the main source of Lin Dan's input, Nanshan underground river was historical pollution, whereas there was a new HCHs input from Ganjiachao in Qingmuguan upstream. Compared with the water bodies at home and abroad, the concentrations of HCHs and DDTs in Nanshan underground river water were at low level, whereas those in Qingmuguan were at medium to high level. Comparing with the hygienic standard of foreign water, it could be observed that Nanshan underground river and Qingmuguan underground river were not able to meet the standard of drinking water safety standard. For the sake of protecting the ecological environment of the underground river, land application of organic chlorine pesticide should be banned in Qingmuguan.

[Comparison Study of the Alkanes in Different Aquifer Medium Under Qingmuguan Underground System].

Dissolved alkanes were collected from Dalv spring and Jiangjia spring from July to November, 2013, and were quantitatively analyzed by the gas chromatography-mass spectrometer (GC-MS). The results show that the total content of dissolved alkanes in Dalv spring is 175-3279 ng x L(-1), with a mean value of 1011 ng x L(-1). In Jiangjia spring, the total content of dissolved alkanes is 282-775 ng x L(-1), with a mean value of 527 ng x L(-1). Ratios of the content of alkanes with high carbon number( C25-C32) to the total alkanes vary from 27.89% to 52.92% in Dalv spring, and 23.66% to 49.73% in Jangjia spring. Combined with CPI and OEP the relative contribution to the dissolved alkanes of higher plants are increasing in Dalv spring, however, it is different in Jiangjia spring. In addition, the values of L/H couldn't reflect different organic contributions to the dissolved alkanes, and the values of TAR may relate with rainfall.

[Sources, Migration and Conversion of Dissolved Alkanes, Dissolved Fatty Acids in a Karst Underground River Water, in Chongqing Area].

Dissolved alkanes and dissolved fatty acids were collected from Qingmuguan underground river in July, October 2013. By gas chromatography-mass spectrometer (GC-MS), alkanes and fatty acids were quantitatively analyzed. The results showed that average contents of alkanes and fatty acids were 1 354 ng.L-1, 24203 ng.L-1 in July, and 667 ng.L-1, 2526 ng.L-1 in October respectively. With the increasing migration distance of dissolved alkanes and dissolved fatty acids in underground river, their contents decreased. Based on the molecular characteristic indices of alkanes, like CPI, OEP, Paq and R, dissolved alkanes were mainly originated from microorganisms in July, and aquatic plants in October. Saturated straight-chain fatty acid had the highest contents in all samples with the dominant peak in C16:0, combined with the characteristics of carbon peak, algae or bacteria might be the dominant source of dissolved fatty acids.

[Sources, Migration and Conversion of Dissolved Sterols in Qingmuguan Underground River].

Water samples were collected from the Qinmuguan underground river from July to November in 2013. By gas chromatography-mass spectrometer (GC-MS), dissolved sterols were quantitatively analyzed. The results show that the average variation content of dissolved sterols ranges from 415 to 629 ng x L(-1), with the increasing migration distance of dissolved sterols in underground river, its contents are decreased. Between the inlet and outlet of Qingmuguan underground river, the average variation contents of dissolved sterol are between 724 and 374 ng x L(-1), and the average variation ratios of the content of stigmasterol with cholesterol range from 0.29 to 0.12. In short, their values are decreased accompanied by the increasing migration distance of underground river. The composing component in dissolved sterols varied differently between July to December, and the main component of dissolved sterols is cholesterin, the ratios of the content of dissolved sterols with cholesterin to the total dissolved sterols range from 37.30% to 94.85%. In addition, the ratios of the content of dissolved sterols with coprostanol to cholesterin, coprostanol to cholesterin are below 0.2 respectively, indicating the water quality of underground river is not contaminated by domestic sewage, but with the passage of time water quality tends to deterioration.

[Variation Characteristics and Sources of Polycyclic Aromatic Hydrocarbons in Karst Subterranean River During Rainfall Events].

The water samples were continuously collected at the outlet of Nanshan Laolongdong subterranean river basin, which is located in Chongqing, during the rainfall event in June 2014. Sixteen priority polycyclic aromatic hydrocarbons (PAHs) in water were quantitatively analyzed by gas chromatography-mass spectrometry (GC-MS). The objectives of this study were to reveal the variation characteristics and sources of PAH16 in karst subterranean river during the rainfall event. The results showed that the subterranean river responded promptly to the rainfall, and there were four peaks of the total concentrations of PAH16, two peaks occurred during the flow rise stage, the others were in the maximum flow and flow decline stages. The total concentrations of PAH16 ranged 101-3 624 ng x L(-1), with a mean of 578 ng x L(-1), the total concentrations of 7 carcinogenic PAHs ranged ND-336 ng x L(-1), with a mean of 31.1 ng x L(-1). The PAH compositional profiles were dominated by 2,3-ring compounds, which accounted for 86.17% of the total concentrations of PAH16. The total concentrations of PAH16 were most influenced by the rainfall, through the cleaning of atmospheric pollutants by the rain and the scouring of the surface contaminants by the rainfall runoff. The PAHs in water mainly originated from the incomplete combustion of petroleum products and fossil fuels such as coal, as well as natural digenetic process. Compared to other areas in the world, the concentrations of PAH16 were generally at moderately polluted and heavily polluted levels.