Yongyu Li

Occurrence of polycyclic aromatic hydrocarbons (PAHs) in seawater from the Western Taiwan Strait, China

Seawater samples (including surface water and bottom water) were collected from the Western Taiwan Strait (WTS) during June 24-25, 2009; polycyclic aromatic hydrocarbons (PAHs) in dissolved phase and particulate phase were analyzed, respectively. The results showed that the total concentrations of PAHs in the dissolved phase and particulate phase were ranged from 12.3 to 58.0 ng L(-1), and 10.3-45.5 ng L(-1), which showed a low-middle contamination level in the China Seas. The spatial variability of PAHs may be related to the complicated currents of WTS, especially the Min-Zhe coastal current. PAHs diagnostic ratios suggested that PAHs mainly originated from the inputs of pyrolytic (combustion) sources, which might be contributed to land-based atmospheric deposition. The particle-water partition coefficients of individual PAH showed that partitions were not correlated with suspended particulate matter content, dissolved organic carbon or salinity, similar to the Yangtze coastal area.

Occurrence and distribution of conventional and new classes of per- and polyfluoroalkyl substances (PFASs) in the South China Sea.

Concentrations of 23 per- and polyfluoroalkyl substances (PFASs), including new classes of PFASs, in seawater samples were investigated for their occurrence and the interaction of the ocean currents with the distribution of PFASs in the South China Sea. This study revealed that socio-economic development was associated with the PFAS contamination in coastal regions of South China. Significant correlations between concentration of total PFASs with gross domestic product (GDP) per capita and population density were found in the areas, suggesting that the influence of intense human activities in these areas may have resulted in higher PFAS contamination to the adjacent environment. Di-substituted polyfluoroalkyl phosphate (diPAP), one of the potential replacements for PFASs, was only detected in the heavily developed region, namely Pearl River Delta (PRD). Total PFAS concentrations, ranging from 195 to 4925 pg/L, were detected at 51 sampling stations of the South China Sea. The results also confirmed that PFAS contamination in the South China Sea is strongly affected by the ocean currents. In comparison to perfluoroactane sulfonate (PFOS) concentrations measured nine years ago at the same locations, the concentrations in this study were found to be two times higher. This indicated that the use and production of perfluoroalkyl sulfonates (PFSAs) has been continuing in the region.

Enrichment and partitioning of polycyclic aromatic hydrocarbons in the sea surface microlayer and subsurface water along the coast of Xiamen Island, China

Sea microlayer (SML) and subsurface water (SSW) samples were collected around Xiamen Island to study the enrichment and partitioning of polycyclic aromatic hydrocarbons (PAHs). Total PAH concentrations ranged from 93.43 to 411.05 ng L(-1) in the SML and 49.29-279.42 ng L(-1) in the SSW. Compared with the results of previous studies before pollution control measurements, PAHs levels decreased significantly. The enrichment factors (EFs) of dissolved and particulate PAHs varied from 0.68 to 2.71 and 0.43-3.56. EFs showed the consistent enrichment trends with sites and exhibited different enrichment characteristics between 2 and 3 ring PAHs and 4 ring PAHs. Furthermore, the much higher concentrations of BaP (strong carcinogenicity) were accompanied by higher EFs in the SML samples from the Western Xiamen Harbour, which together indicated the risk of impacts to the fish eggs that usually float on the SML water after exposure to oil spills and combustion, contributed directly by the port and shipping activities.

Levels of endocrine disrupting compounds in South China Sea

The occurrence of estrogens in the aquatic environment has become a major concern worldwide because of their strong endocrine disrupting potency. In this study, concentrations of four estrogenic compounds, estrone (E1), 17β-estradiol (E2), 17α-ethynylestradiol (EE2), estriol (E3) were determined with liquid chromatography-tandem mass spectrometry analyses in surface water from South China Sea, and distributions and potential risks of their estrogenic activity were assessed. The estrogenic compounds E1, E2 and E3 were detected in most of the samples, with their concentrations up to 11.16, 3.71 and 21.63 ng L(-1). However, EE2 was only detected in 3 samples. Causality analysis, EEQ values from chemical analysis identified E2 as the main responsible compounds. Based on the EEQ values in the surface water, high estrogenic risks were in the coastal water, and low estrogenic risks in the open sea.

Seasonal Variation of Terrigenous Polycyclic Aromatic Hydrocarbons along the Marginal Seas of China: Input, Phase Partitioning, and Ocean-Current Transport

To study the spatial distributions and seasonal differences of concentrations, source identification, and phase partitioning of polycyclic aromatic hydrocarbons (PAHs) in surface water, intensive sampling was carried out along the marginal seas of China in four seasons. In the northern South China Sea (SCS), the highest PAH levels occurred in the summer (July to August) and autumn (October to November). In the East China Sea (ECS) and the Yellow Sea, the highest occurred in the summer (August) and winter (December). In all areas, the lowest PAH levels were found in the spring (May to June). The estimated mass inventory of PAHs in the surface water (0-5 m) of the northern SCS and ECS accounted for less than 8% of PAHs outflow into the offshore environment. That showed the consistent seasonal variation with PAHs levels. Land- and ocean-based emissions, surface runoff, and the open seawater dilution were the most important environmental factors influencing the seasonal heterogeneity and the spatial distributions of PAH in the surface water. The decline of observed organic carbon normalized partition coefficients in the four seasons was probably affected by the presence of submicrometer-sized soot particles accompanying the PAH outflow from China.

Temporal trends and transport of perfluoroalkyl substances (PFASs) in a subtropical estuary: Jiulong River Estuary, Fujian, China

The seasonal variations and spatial distributions of fifteen perfluoroalkyl substances (PFASs) were investigated in the water of the subtropical Jiulong River Estuary (JRE) in Fujian, China. The concentrations and composition profiles of PFASs showed significant seasonal variations. ∑PFASs concentrations ranged from 4.8 to 37.6 ng L-1, 12.2 to 110 ng L-1 and 3.3 to 43.0 ng L-1 in the dry, medium and wet seasons, respectively. Perfluorooctane sulfonate (PFOS) was found to be the most abundant PFAS in the dry season, with a composition of 33% ± 5%, Perfluorohexanoic acid PFHxA (47% ± 13%) and perfluoropentanoic acid (PFPeA) (52% ± 15%) were the dominant compounds in the medium and wet seasons, respectively. Seasonal and spatial distributions of ∑PFASs were different in the upstream and downstream sections. High concentration of PFHxA occurred in the medium season, and showed a linear decreasing trend from upstream to downstream. The majority of other PFASs did not show clear seasonal variation. Composition profiles indicated that the JRE was mainly contaminated by short-chain perfluoroalkyl carboxylic acids (PFCAs), shipbuilding industry, multiple wastewater and river runoff were identified as major potential sources.

Fossil Fuel-Derived Polycyclic Aromatic Hydrocarbons in the Taiwan Strait, China, and Fluxes across the Air-Water Interface

On the basis of the application of compound-specific radiocarbon analysis (CSRA) and air-water exchange models, the contributions of fossil fuel and biomass burning derived polycyclic aromatic hydrocarbons (PAHs) as well as their air-water transport were elucidated. The results showed that fossil fuel-derived PAHs (an average contribution of 89%) presented the net volatilization process at the air-water interface of the Taiwan Strait in summer. Net volatile fluxes of the dominant fluorene and phenanthrene (>58% of the total PAHs) were 27 ± 2.8 μg m-2 day-1, significantly higher than the dry deposition fluxes (average 0.43 μg m-2 day-1). The Δ14C contents of selected PAHs (fluorene, phenanthrene plus anthracene, fluoranthene, and pyrene) determined by CSRA in the dissolved seawater ranged from -997 ± 4‰ to -873 ± 6‰, indicating that 89-100% (95 ± 4%) of PAHs were supplied by fossil fuels. The South China Sea warm current originating from the southwest China in summer (98%) and the Min-Zhe coastal current originating from the north China in winter (97%) input more fossil fuel PAHs than the Jiulong River estuary (90%) and Xiamen harbor water (93%). The more radioactive decayed 14C of fluoranthene (a 4-ring PAH) than that of phenanthrene and anthracene (3-ring PAHs) represented a greater fossil fuel contribution to the former in dissolved seawater.