["Load-Unload" Effect of Manganese Oxides on Phosphorus in Surface Water of the Pearl River Estuary].

Phosphorus (P) conveyed by surface runoff plays an essential role in regulating nutrient balance and primary production in estuarine waters. In this study, basic physiochemical properties, total phosphorus (TP, including speciation), particulate iron (PFe), particulate manganese (PMn), and particulate aluminum (PAl) of the surface water in the Pearl River Estuary (PRE) in different seasons were determined to investigate the spatiotemporal distribution characteristics of P and to identify the crucial factor controlling P migration and transformation in the freshwater-saltwater interaction zone. TP concentrations (28.

[Impact of Urbanization on the Sources of Dissolved -alkane in Underground River].

To investigate the influence of urbanization on the component features of dissolved -alkanes (D-ALK) in the underground river in the dry season, water samples were collected respectively at the outlet of the two underground rivers. Components of D-ALK in these samples were quantitatively analyzed by gas chromatography-mass spectrometry (GC-MS). The results showed that the distribution of D-ALK carbon number at the two sites ranged from nC to nC in dry season.

[Sources and Variation Characteristics of Dissolved Lipid Biomarkers in a Typical Karst Underground River].

Water samples in Qingmuguan underground river were collected to determine the concentration of dissolved lipids, and their sources, composition and migration characteristics in underground river were studied. The results were obtained as follows. (1) The average content of various dissolved lipids decreased with increasing distance of migration in Qingmuguan underground river, and the most distinctive was dissolved saturated straight chain fatty acids with its content decreasing by about 81.

[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 from May to July, respectively, and followed the order of SFA> MUFA> BrFA> PUFA.

[Fecal Contamination in Laolongdong Underground River as Measured by the Sterol Biomarkers].

To investigate whether the underground river was polluted or not, and trace the source of fecal sterols, the particulate water samples were collected from typical karst underground river named Laolongdong in Nan'an District, Chongqing Municipality in October, 2014, January, March and May, 2015. Ten prior steroids in the underground river were quantitatively analyzed by the gas chromatography-mass spectrometer (GC-MS). The results showed ten steroids including 9 sterols and 1 ketone were detected.

[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 and 3302 to 45254 ng·L, respectively.

[Distribution and Transportation Characteristics of Heavy Metals in Nanshan Laolongdong Subterranean River System and Its Capacity of Self-Purification in Chongqing].

For figuring out the distribution and transportation characteristics of heavy metals Mn, Pb, Cu and As among overlying water-pore water-surface sediments so as to offer a scientific basis for the development of urban construction and protection of karst groundwater, overlying water, pore water and surface sediment samples were collected in December 2013 ( winter) and June 2014 (summer) respectively. Results show that the detection rates of Mn, Pb, Cu and As are 100% both in overlying water and pore water with the concentration Mn > Pb > Cu > As, summer > winter, pore water > overlying water, respectively, and the groundwater could not be a source of drinking water because of the excessive content of Mn and Pb. In addition, the concentration of heavy metals Mn, Pb, Cu and As in pore water are higher than that in overlying water, indicating that heavy metals could diffuse into overlying water from pore water because of concentration gradient, especially in summertime.

[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.

[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.

[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.

[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).

[Vertical Migration Characteristics of Organochlorine Pesticides in Overlying Soil in Karst Terranes and Its Impact on Groundwater].

Five soil profiles and four typical epikarst springs were selected in Nanchuan District, Chongqing Municipality as objects of the study on vertical migration of organochlorine pesticides (OCPs) in the soils and its impact on groundwater. OCPs in soil and epikarst spring water samples were quantitatively analyzed by gas chromatography. The results showed that HCHs and DDTs were detected in all the 5 soil profiles, varying in the range of 0.

[Difference of Karst Carbon Sink Under Different Land Use and Land Cover Areas in Dry Season].

In order to identify the distinction of soil CO2 consumed by carbonate rock dissolution, Baishuwan spring, Lanhuagou spring and Hougou spring were selected as objects to monitor the hydrochemistry from November 2013 to May 2014. The results showed that the highest HCO3- concentration was observed in Baishuwan spring which is covered by pine forest, while the lowest HCO3- concentration was observed in Hougou spring which is mainly covered by cultivated land. In Baishuwan spring, HCO3- was mainly derived from carbonic acid dissolving carbonate rock and the molar ratio between Ca(2+) + Mg2+ and HCO3- was close to 0.

[Altitudinal Gradient Distribution and Source Analysis of PAHs Content of Topsoil in Jinfo Mountain, Chongqing].

The condensation effect has made high mountains the storage vault of durable organic pollutants. This research measured the content and constitutes of polycyclic aromatic hydrocarbons (PAHs) in 10 topsoil samples collected at different altitudes from the south slope of Chongqing Jinfo Mountain by gas chromatograph-mass spectrometer (GC/MC). And the pollution source of PAHs was analyzed by ratio method and principal component regression.

[Contamination and ecological risk assessment of polycyclic aromatic hydrocarbons in surface sediment in karst underground river].

In order to understand pollution characteristics and ecological risk of polycyclic aromatic hydrocarbons (PAHs) in surface sediment from Laolongdong underground river, the concentration and composition of 16 priority PAHs were analyzed. The results showed that the total concentrations of PAHs ranged from 58.2 to 3 598 ng x g(-1), and most of the values were between 100 and 5 000 ng x g(-1).

[Formation of geochemistry in underground river under rainfall conditions: an examule for underground river at Xueyu Cave, Chongqing].

Through the monitoring of geochemical indexes in underground river of Xueyu Cave in Chongqing under rainfall conditions, we found that all indexes responded quickly to rainfall, and there was a correlation among them. Each index was analyzed with the principal component analysis, three main components were extracted which can represent 82.761% of the information to reflect the formation of geochemistry in underground river under rainfall conditions.