Xiaohui Pan

Occurrence and distribution of antibiotics in the Beibu Gulf, China: Impacts of river discharge and aquaculture activities

The occurrence and distribution of eleven selected antibiotics belonging to three groups were investigated in the Beibu Gulf. In addition, the potential effects of water discharged from four rivers and aquaculture activities were analyzed. Erythromycin-H₂O, sulfamethoxazole and trimethoprim were the most frequently detected compounds, with mean concentrations ranging from 0.51 to 6.30 ng L⁻¹. The concentrations of the rivers were generally higher than those of the gulf, implying that river discharge has an important effect on the Beibu Gulf. The concentrations of erythromycin-H₂O, sulfamethoxazole and sulfadimidine in the vicinity of aquaculture activities were higher, suggesting that a higher intensity of aquaculture activities could contribute to increasing levels of antibiotics in the environment. According to MEC (measured environmental concentration)/PNEC (predicted no-effect concentration), erythromycin, sulfamethoxazole and clarithromycin may present possible environmental risk to Pseudokirchneriella subcapitata, Synechococcus leopoliensis and P. subcapitata, respectively; therefore, attention should be given to the long-term ecological effects caused by the continuous discharge of antibiotics in the Beibu Gulf.

Occurrence and spatial distribution of organophosphate ester flame retardants and plasticizers in 40 rivers draining into the Bohai Sea, north China.

Organophosphate esters (OPEs) are alternatives to polybrominated diphenyl ethers, often used as flame-retardants and plasticizers. There are few reports of OPEs in river water. This study focused on the occurrence and spatial distribution of 11 OPE congeners and one synthetic intermediate triphenylphosphine oxide (TPPO) in 40 major rivers entering into the Bohai Sea. Total OPEs ranged from 9.6 to 1549 ng L(-1), with an average of 300 ng L(-1). Tris(1-chloro-2-propyl) phosphate (TCPP) (4.6-921 ng L(-1), mean: 186 ng L(-1)) and tris(2-choroethyl) phosphate (TCEP) (1.3-268 ng L(-1), mean: 80.2 ng L(-1)) were the most abundant OPEs and their distribution patterns are similar, indicating the same source (r = 0.61, P < 0.05) and the influence of large production and consumption of chlorinated OPEs in the region. Priority should be given to TCPP, PCEP and TPPO due to their high concentrations in the rivers and potential threat to aquatic organisms.

Short- and Medium-Chain Chlorinated Paraffins in Air and Soil of Subtropical Terrestrial Environment in the Pearl River Delta, South China: Distribution, Composition, Atmospheric Deposition Fluxes, and Environmental Fate

Research on the environmental fate of short- and medium-chain chlorinated paraffins (SCCPs and MCCPs) in highly industrialized subtropical areas is still scarce. Air, soil, and atmospheric deposition process in the Pearl River Delta of South China were investigated, and the average SCCP and MCCP concentrations were 5.2 μg/sampler (17.69 ng/m(3)) and 4.1 μg/sampler for passive air samples, 18.3 and 59.3 ng/g for soil samples, and 5.0 and 5.3 μg/(m(2)d) for deposition samples, respectively. Influenced by primary sources and the properties of chlorinated paraffins (CPs), a gradient trend of concentrations and a fractionation of composition from more to less industrialized areas were discovered. Intense seasonal variations with high levels in summer air and winter deposition samples indicated that the air and deposition CP levels were controlled mainly by the vapor and particle phase, respectively. Complex environmental processes like volatilization and fractionation resulted in different CP profiles in different environment matrixes and sampling locations, with C(10-11) C(l6-7) and C(14) C(l6-7), C(10-12) C(l6-7) and C(14) C(l6-8), and C(11-12) C(l6-8) and C(14) C(l7-8) dominating in air, soil, and atmospheric deposition, respectively. Shorter-chain and less chlorinated congeners were enriched in air in the less industrialized areas, while longer-chain and higher chlorinated congeners were concentrated in soil in the more industrialized areas. This is suggesting that the gaseous transport of CPs is the dominant mechanism responsible for the higher concentrations of lighter and likely more mobile CPs in the rural areas.

Atmospheric Short-Chain Chlorinated Paraffins in China, Japan, and South Korea

This study presents the first investigation of concentrations and congener group patterns of atmospheric short-chain chlorinated paraffins (SCCPs) throughout East Asia. Based on an absorption rate calibration experiment, a spatial survey of SCCPs was performed using passive air samplers in China, Japan, and South Korea during two separate periods in 2008. The atmospheric concentrations of SCCPs in China were clearly greater than those in Japan and South Korea, both of which exceed the levels determined for other regions of the world. C(10) components were the most abundant type of SCCPs in China, whereas C(11) components were dominant in Japan and South Korea. With respect to the total chlorine content, Cl(6) and Cl(5) were the predominant compounds in China and Japan; however, Cl(6) and Cl(7) were predominant in South Korea. A similar pattern was also found for remote sites within China, Japan, and South Korea, respectively. Together with the back-trajectories calculated for the remote sites, the results indicate that the SCCPs in the air of East Asia were mainly influenced by local sources due to their relatively low long-range atmospheric transport potential compared to other POPs.

Perfluoroalkyl acids (PFAAs) in riverine and coastal sediments of Laizhou Bay, North China

This study investigates the concentrations and distributions of perfluoroalkyl acids (PFAAs), including perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkane sulphonates (PFSAs), in surface sediments from Laizhou Bay and its adjacent rivers. ∑PFAAs showed much higher levels in the river sediment (with a mean of 5.25 ng/g dw) than in the coastal sediment (with a mean of 0.76 ng/g dw). Perfluorooctanoic acid (PFOA) was the predominant compound, accounting for 50% to 97% of ∑PFAA concentrations in 70% of the samples. The highest concentrations were detected in the Xiaoqing River, possibly due to the rapid development of the nearby fluorochemical industry. Hydrodynamics strongly influenced the distribution of PFAAs in Laizhou Bay. The hydrophilic property of shorter-chained PFAAs (C≤8) allowed them to be transported to the inner bay via currents, to adsorb onto suspended sediment and then to be deposited. The Xiaoqing River showed the highest PFOA concentration (76.9 ng/g dw) among the bodies of sediment that had been studied worldwide, which might pose a potential threat for the benthic organisms of this river.

Polybrominated diphenyl ethers (PBDEs) in the riverine and marine sediments of the Laizhou Bay area, North China

62 riverine and marine sediments were collected from the Laizhou Bay area, where the largest manufacturing base of brominated flame retardants (BFRs) in Asia is located. Eight polybrominated diphenyl ethers (PBDEs) were analyzed to investigate the impact of rapidly-developed bromine industries on the regional aquatic system. PBDE concentrations varied largely in riverine sediments. Σ(7)PBDEs (including BDE 28, 47, 99, 100, 153, 154 and 183) and BDE 209 ranged from 0.01 to 53 ng g(-1) dw and from 0.74 to 285 ng g(-1) dw with a mean value of 4.5 ng g(-1) dw and 54 ng g(-1) dw, respectively, indicating a strong influence of direct pollution discharges from local factories. In marine sediments, Σ(7)PBDEs and BDE 209 ranged from not detected (nd) to 0.66 ng g(-1) dw and from 0.66 to 12 ng g(-1) dw with a mean value of 0.32 ng g(-1) dw and 5.1 ng g(-1) dw, respectively. PBDE concentrations were mostly <10 ng g(-1) dw for Σ(7)PBDEs and <50 ng g(-1) dw for BDE 209, which are at a relatively low level for monitored riverine and coastal sediments around the world. Even at the most contaminated sites in Laizhou Bay area, PBDE concentrations were not among the highest concentrations reported in the literature. Congener compositions were dominated by BDE 209 (57.2-99.9% of the sum of BDE congeners), with minor contributions from penta- and octa-BDE products. Tri- to octa-BDE congeners were well correlated among each other (r > 0.75) and thus sources from similar mixing of penta- and octa-BDE products were suggested in this area. Compared with riverine sediments, a much better correlation between PBDE concentrations with TOC was observed in marine environment. The congener pattern changed and their correlation coefficients among each other were remarkably reduced. Contributions of BDE 28, 47 and 99 to Σ(7)PBDEs were generally the same in almost all the marine sites, while it was distinctively higher for BDE 153. These are probably attributable to several reasons, such as contributions by atmospheric deposition and/or redistribution between particles of various sizes during and/or after fluvial transportation combined with the difference of physiochemical properties of BDE congeners.

Polychlorinated naphthalenes (PCNs) in riverine and marine sediments of the Laizhou Bay area, North China.

PCN congeners were analyzed in marine and riverine sediments of the Laizhou Bay area, North China. Concentrations of PCNs ranged from 0.12 to 5.1 ng g(-)(1) dry weight (dw) with a mean value of 1.1 ng g(-)(1) dw. The levels of PCNs varied largely, with industrial group approximately ten folds higher than those of the rural in riverine sediment. A strong impact by direct discharge from local factories was suggested. Similar compositional profiles were found within groups. High resemblance of compositional profiles between industrial samples and Halowax 1014 was observed. It was indicated that PCNs in riverine sediments were mainly from release of industrial usage, with additional contributions from industrial thermal process at certain sites. In marine sediments, it was suggested that PCNs along the coast of Laizhou Bay were mainly controlled by riverine input. While in the central bay, PCN distributions were possibly impacted by combined multiple factors.

Selected current-use and historic-use pesticides in air and seawater of the Bohai and Yellow Seas, China

Consumption of pesticides in China has increased rapidly in recent years; however, occurrence and fate of current-use pesticides (CUPs) in China coastal waters are poorly understood. Globally banned pesticides, so-called historic-use pesticides (HUPs), are still commonly observed in the environment. In this work, air and surface seawater samples taken from the Bohai and Yellow Seas in May 2012 were analyzed for CUPs including trifluralin, quintozene, chlorothalonil, dicofol, chlorpyrifos, and dacthal, as well as HUPs (hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), and endosulfan). CUP profile in both air and seawater samples generally reflected their consumption patterns in China. HUPs in the air and seawater samples were in comparable levels as those of CUPs with high concentrations. alpha-Endosulfan, dicofol, and chlorothalonil showed strong net deposition likely resulting from their intensive use in recent years, while CUPs with low consumption amount (quintozene and dacthal) were close to equilibrium at most samplings sites. Another CUP with high usage amout (i.e., chlorpyrifos) underwent volatilization possibly due to its longer half-life in seawater than that in air. alpha-HCH and gamma-HCH were close to equilibrium in the Bohai Sea, but mainly underwent net deposition in the Yellow Sea. The net deposition of alpha-HCH could be attributed to polluted air pulses from the East China identified by air mass back trajectories. beta-HCH showed net volatilization in the Bohai Sea, which was driven by its relative enrichment in seawater. HCB either slightly favored net volatilization or was close to equilibrium in the Bohai and Yellow Seas.

Sources and preservation of sedimentary organic matter in the Southern Bohai Sea and the Yellow Sea: Evidence from lipid biomarkers

The region of Southern Bohai Sea (SBS) and Yellow Sea (YS) represents one of the best examples of large river-dominated ocean margins. The transport and accumulation of sediments played a primary role in distribution of the lipids in the region and could lead to a preferential accumulation of these more refractory land-based lipids. The spatial distribution of total organic carbon (TOC) matched with the lipid distributions over the shelf, and high TOC presented in the central YS, but TOC burial fluxes decreased from 110 ton/km(2)/yr of SBS to 25-32 ton/km(2)/yr of YS. Good correlations were observed between terrestrial n-alkanes and TOC in the sediments of SBS and northern YS, but they were poor for southern YS, meanwhile higher ratios of nC27+nC29+nC31/nC15+nC17+nC19 (12±6) were observed in SBS, and lower in YS (2.2±1.0), suggesting the Yellow River discharge was an important source of terrestrial organic matter to the shelf.