Seasonal variation and spatial transport of polycyclic aromatic hydrocarbons in water of the subtropical Jiulong River watershed and estuary, Southeast China.

Riverine runoff is one of the most important pathways of pollutants entering the oceans. To study the seasonal variations, spatial transports, sources and mass fluxes of polycyclic aromatic hydrocarbons (PAHs) from the subtropical Jiulong River watershed to estuary, water samples were collected in wet and dry seasons. PAH concentrations showed significant temporal-spatial variations (ANOVA, p < 0.05). In the watershed, PAH concentrations in wet season (48.6 ±â€¯18.2 ng L-1) were significantly lower than in dry season (90.3 ±â€¯18.5 ng L-1). In contrast, estuarine PAH concentrations in wet season (67.1 ±â€¯24.6 ng L-1) were significantly higher than in dry season (27.4 ±â€¯10.6 ng L-1) (p < 0.0001). The spatial variations of PAH concentrations in wet and dry seasons reflected positive and restricted transport processes occurred in the river. These findings might be subjected to seasonal changes in precipitation, water discharge, hydrodynamic conditions, and human activities. The compositional patterns of PAHs illustrated that fluorene and phenanthrene were the dominant compounds in the watershed, while phenanthrene was predominant in the estuary. Source analysis by molecular diagnostic ratios and PMF model indicated that fossil fuel and biomass combustion and petroleum both contributed to the presence of PAHs, and the high contributions of pyrogenic PAHs might be related to urban rainstorm runoff in winter and atmospheric inputs in winter. Although the estimated flux of PAHs from watershed to estuary was about 676 kg yr-1 with a low level by comparing the data obtained in the worldwide, continue concern of PAHs in the Jiulong River is recommended due to the intense human activities.

Storm induced estuarine turbidity maxima and controls on nutrient fluxes across river-estuary-coast continuum.

Climate change is likely to increase the frequency and intensity of tropical storms. However, the impacts of major storms on nutrient cycling processes in the river-estuary-coast continuum are poorly understood. Continuous observations were made at lower river stations and on a transect down the Jiulong River Estuary in south east China for three storms in 2013-2014. There were major increases in both dissolved nutrients and suspended particulate matter (SPM) brought down the river during storms. Strong Estuarine Turbidity Maxima (ETM) were observed during major storms and were the result of SPM brought down rivers augmented by sediment scoured within the Upper Estuary (salinity=0psu) and possibly also from behind the dikes opened for flood control. There were major increases in dissolved nutrients (nitrate, ammonium and phosphate) in the Upper Estuary particularly during major Storms C (July 2013) and D (May 2014). These increases were probably due to river inflows with surrounding runoff, pore water supply and nutrients desorbed from scoured sediment. During major Storm D there were greater nutrient fluxes through the estuary-coast interface compared to the nutrients supplied through the river-estuary interface while the opposite pattern was observed during normal flow. The increased supply of ammonium and phosphate to the coastal region caused increased chlorophyll a once the light inhibiting SPM had been removed from the water column. This is likely to increase the potential of eutrophication. Storm induced increases in N:P:Si supplied from the estuary to the coastal region increased the degree of P limitation.

Metaproteomics of marine viral concentrates reveals key viral populations and abundant periplasmic proteins in the oligotrophic deep chlorophyll maximum of the South China Sea.

Viral concentrates (VCs), containing bioinformative DNA and proteins, have been used to study viral diversity, viral metagenomics and virus-host interactions in natural ecosystems. Besides viruses, VCs also contain many noncellular biological components including diverse functional proteins. Here, we used a shotgun proteomic approach to characterize the proteins of VCs collected from the oligotrophic deep chlorophyll maximum (DCM) of the South China Sea. Proteins of viruses infecting picophytoplankton, that is, cyanobacteria and prasinophytes, and heterotrophic bacterioplankton, such as SAR11 and SAR116, dominated the viral proteome. Almost no proteins from RNA viruses or known gene transfer agents were detected, suggesting that they were not abundant at the sampling site. Remarkably, nonviral proteins made up about two thirds of VC proteins, including overwhelmingly abundant periplasmic transporters for nutrient acquisition and proteins for diverse cellular processes, that is, translation, energy metabolism and one carbon metabolism. Interestingly, three 56 kDa selenium-binding proteins putatively involved in peroxide reduction from gammaproteobacteria were abundant in the VCs, suggesting active removal of peroxide compounds at DCM. Our study demonstrated that metaproteomics provides a valuable avenue to explore the diversity and structure of the viral community and also the pivotal biological functions affiliated with microbes in the natural environment.

Modeling nutrient sources, transport and management strategies in a coastal watershed, Southeast China.

Integrated watershed management requires an analytical model capable of revealing the full range of impacts that would be caused by the uses and developments in the watershed. The SPAtially Referenced Regressions On Watershed Attributes (SPARROW) model was developed in this study to provide empirical estimates of the sources, transport of total nitrogen (TN) and total phosphorus (TP) and to develop nutrient management strategies in the Jiulong River Watershed, southeast China that has enormous influence on the region's ecological safety. We calibrated the model using data related to daily streamflow, monthly TN and TP concentrations in 2014 at 30 locations. The model produced R2 values for TN with 0.95 and TP with 0.94. It was found that for the entire watershed, TN came from fertilizer application (43%), livestock breeding (39%) and sewage discharge (18%), while TP came from livestock breeding (46%), fertilizer application (46%), and industrial discharge (8%). Fifty-eight percent of the TN and 80% of the TP in upstream reaches are delivered to the outlets of North and West rivers. A scenario analysis with SPARROW was coupled to develop suitable management strategies. Results revealed that controlling nutrient sources was effective in improving water quality. Normally sharp reduction in nutrient sources is not operational feasible. Hence, it is recommended that preventing nutrient on land from entering into the river as a suitable strategy in watershed management.

Polybrominated diphenyl ethers, organochlorine pesticides, and polycyclic aromatic hydrocarbons in water from the Jiulong River Estuary, China: levels, distributions, influencing factors, and risk assessment.

Estuarine systems play an important role in the transportation and transformation of organic pollutants from rivers. Polybrominated diphenyl ether (PBDE), organochlorine pesticide (OCP), and polycyclic aromatic hydrocarbon (PAH) concentrations in water of the Jiulong River Estuary (JRE), China, were investigated to characterize their distribution, possible source, and potential ecological risk as well as the influencing factors. The total concentrations of PBDEs, OCPs, and PAHs varied from 5.2 to 12.3 pg L-1, from 29.1 to 96.4 ng L-1, and from 28.6 to 48.5 ng L-1, respectively. Their compositions were all consistent at different stations; even the input pathways were multifarious. A source analysis showed that PBDEs may come from the flame retardant usages of penta-BDE and deca-BDE; hexachlorocyclohexane isomers (HCHs) were from the use of technical HCHs, while DDTs were attributed to early residuals of industrial sources, and PAHs were mainly from pyrolytic sources. The spatial distributions of PBDEs and OCPs were quite similar with their concentrations, decreasing along the estuary and then increasing when passing the Xiamen Harbor. PAH concentrations were similar along the whole estuary, suggesting that local sources and hydrological conditions might be the influencing factors. The concentrations of these pollutants changed with tidal conditions and were positively correlated with SPM, DOC, and chlorophyll a but negatively correlated with salinity. The ecological risk assessment revealed that OCPs and PAHs posed slightly higher potential risks to aquatic organism in the study area.

Distributions of organochlorine compounds in sediments from Jiulong River Estuary and adjacent Western Taiwan Strait: Implications of transport, sources and inventories.

Estuaries and coastal areas strongly influenced by terrestrial inputs resulted from anthropogenic activities. To study the distributions, origins, potential transport and burden of organochlorine compounds (OCs) from river to marginal sea, organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were investigated in surface sediments collected from a subtropical estuary (Jiulong River Estuary, JRE) and the inner shelf of adjacent Western Taiwan Strait (WTS). The concentrations of OCPs and PCBs were from 5.2 to 551.7 and 1.0-8.1 ng g-1 (dry weight), respectively. OCP concentrations in the JRE were higher than in adjacent WTS, and a decreasing trend with the ascending distance from the estuary to the open sea was observed. Concentrations of DDTs were quite high in the upper reach of the estuary, inferred from antifouling paint on fishing boats of a local shipping company. According to established sediment quality guidelines, DDTs in the JRE posed potential ecological risk. HCHs in the estuary were mainly derived from the weathered HCHs preserved in the agriculture soils via local major river runoffs. OCPs patterns showed that OCPs in the south coast of WTS were resulted from local sources via river input, while OCPs in the north coast attributed to the long-range transport derived by the Fujian-Zhejiang Coastal Current. Minor variations of PCB concentrations and homologs indicated that PCBs were not the main pollutant in the agricultural region, consistent lighter PCBs reflected industrial PCBs were transported via atmospheric deposition derived by East Asia Monsoon. Moreover, the primary distribution pattern founded for DDTs and the considerable mass inventories and burdens calculated (258.1 ng cm-2 and 10.4 tones for OCPs) that higher than Pearl River Delta and Yangtze River Delta, together suggested that the contaminated sediments in the study area may be a potential source of OCPs to the global ocean.

New insight into the correlations between land use and water quality in a coastal watershed of China: Does point source pollution weaken it?

Uncovering the associations between land use and river water quality is useful for managing land-based pollution in the catchment-coast continuum. However, it is not clear how land use affects water quality in the context of simultaneous point source (PS) pollution. In this study, we develop a self-organizing map (SOM)-based approach to explore the relationship between land use and water quality in the Minjiang River Watershed, Southeast China. Water samples from 139 headwater sub-watersheds were associated with six land use categories, namely, Woodland, Agriculture, Orchard, Built-up, Unused land and Water. Sampling sites are delineated into six clusters based on six water quality parameters: ammonium-N, nitrate-N, total nitrogen, soluble reactive phosphate, total phosphate and potassium permanganate index. Local relationships between land use and water quality among four clusters that have sufficient sample sizes are further identified. There is no significant land use-water quality correlation in one of the four clusters (including 37 sub-watersheds). And the greater the PS pollution is, the less significant the land use-water quality correlations are in clusters. The results demonstrate how PS pollution weakens the land use-water quality correlation. Our method can help to determine whether non-point source or PS pollution exerts greater influence on the quality of the water coming from watershed.

Modeling increased riverine nitrogen export: Source tracking and integrated watershed-coast management.

The global NEWS model was calibrated and then used to quantify the long term trend of dissolved inorganic nitrogen (DIN) export from two tributaries of Jiulong River (SE China). Anthropogenic N inputs contributed 61-92% of river DIN yield which increased from 337 in 1980s to 1662 kg N km(-2) yr(-1) in 2000s for the North River, and from 653 to 3097 kg N km(-2) yr(-1) for the West River. North River and West River contributed 55% and 45% respectively of DIN loading to the estuary. Rapid development and poor management driven by national policies were responsible for increasing riverine N export. Scenario analysis and source tracking suggest that reductions of anthropogenic N inputs of at least 30% in the North River (emphasis on fertilizer and manure) and 50% in the West River (emphasis on fertilizer) could significantly improve water quality and mitigate eutrophication in both river and coastal waters.

Land classification and change intensity analysis in a coastal watershed of Southeast China.

The aim of this study is to improve the understanding of land changes in the Jiulong River watershed, a coastal watershed of Southeast China. We developed a stratified classification methodology for land mapping, which combines linear stretching, an Iterative Self-Organizing Data Analysis (ISODATA) clustering algorithm, and spatial reclassification. The stratified classification for 2002 generated less overall error than an unstratified classification. The stratified classifications were then used to examine temporal differences at 1986, 1996, 2002, 2007 and 2010. Intensity Analysis was applied to analyze land changes at three levels: time interval, category, and transition. Results showed that land use transformation has been accelerating. Woodland's gains and losses were dormant while the gains and losses of Agriculture, Orchard, Built-up and Bare land were active during all time intervals. Water's losses were active and stationary. The transitions from Agriculture, Orchard, and Water to Built-up were systematically targeting and stationary, while the transition from Woodland to Built-up was systematically avoiding and stationary.

Comparative embryotoxicity of phenanthrene and alkyl-phenanthrene to marine medaka (Oryzias melastigma).

Alkylated polycyclic aromatic hydrocarbons (alkyl-PAHs) are the predominant form of PAHs in oil, comprising 85-95% of total PAHs. However, little attention has been paid to these chemicals in ecological risk assessment of marine oil spill. A comparative study of the toxic effects of phenanthrene and retene (7-isopropyl-1-methylphenanthrene, an alkyl-phenanthrene) on the early life stage of marine medaka (Oryzias melastigma) was conducted. Results showed that retene was significantly more toxic than phenanthrene, and marine medaka could be more sensitive to retene than some freshwater fishes. Retene had a higher excretion rate than phenanthrene during the larvae stage. Both of compounds resulted in developmental malformation of marine medaka embryos, with phenanthrene affecting on peripheral vascular system and yolk sac, while retene affecting on cardiac tissues. The toxicity of phenanthrene might be mainly related to its anesthetic effects, and that of retene might be related to the CYP1A-mediated toxicity of its metabolites.

Quantitative proteomic analysis of cell cycle of the dinoflagellate Prorocentrum donghaiense (Dinophyceae).

Dinoflagellates are the major causative agents of harmful algal blooms in the coastal zone, which has resulted in adverse effects on the marine ecosystem and public health, and has become a global concern. Knowledge of cell cycle regulation in proliferating cells is essential for understanding bloom dynamics, and so this study compared the protein profiles of Prorocentrum donghaiense at different cell cycle phases and identified differentially expressed proteins using 2-D fluorescence difference gel electrophoresis combined with MALDI-TOF-TOF mass spectrometry. The results showed that the synchronized cells of P. donghaiense completed a cell cycle within 24 hours and cell division was phased with the diurnal cycle. Comparison of the protein profiles at four cell cycle phases (G1, S, early and late G2/M) showed that 53 protein spots altered significantly in abundance. Among them, 41 were identified to be involved in a variety of biological processes, e.g. cell cycle and division, RNA metabolism, protein and amino acid metabolism, energy and carbon metabolism, oxidation-reduction processes, and ABC transport. The periodic expression of these proteins was critical to maintain the proper order and function of the cell cycle. This study, to our knowledge, for the first time revealed the major biological processes occurring at different cell cycle phases which provided new insights into the mechanisms regulating the cell cycle and growth of dinoflagellates.

Quantitative proteomic analysis reveals the mode-of-action for chronic mercury hepatotoxicity to marine medaka (Oryzias melastigma).

Mercury (Hg) is a widespread persistent pollutant in aquatic ecosystems. We investigated the protein profiles of medaka (Oryzias melastigma) liver chronically exposed to different mercuric chloride (HgCl2) concentrations (1 or 10 µg/L) for 60 d using two-dimensional difference gel electrophoresis (2D-DIGE), as well as cell ultrastructure and Hg content analysis of the hepatic tissue. The results showed that Hg exposure significantly increased metal accumulation in the liver, and subsequently damaged liver ultrastructure. Comparison of the 2D-DIGE protein profiles of the exposed and control groups revealed that the abundance of 45 protein spots was remarkably altered in response to Hg treatment. The altered spots were subjected to matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry analysis, with the resultant identification of 33 spots. These proteins were mainly involved in cytoskeleton assembly, oxidative stress, and energy production. Among them, several proteins related to mitochondrial function (e.g. respiratory metabolism) were significantly altered in the treated hepatocytes, implying that this organelle might be the primary target for Hg attack in the cells. This study provided new insights into the molecular mechanisms and/or toxic pathways by which chronic Hg hepatotoxicity affects aquatic organisms, and also provided basic information for screening potential biomarkers for aquatic Hg monitoring.

Comparative proteomic analysis reveals proteins putatively involved in toxin biosynthesis in the marine dinoflagellate Alexandrium catenella.

Alexandrium is a neurotoxin-producing dinoflagellate genus resulting in paralytic shellfish poisonings around the world. However, little is known about the toxin biosynthesis mechanism in Alexandrium. This study compared protein profiles of A. catenella collected at different toxin biosynthesis stages (non-toxin synthesis, initial toxin synthesis and toxin synthesizing) coupled with the cell cycle, and identified differentially expressed proteins using 2-DE and MALDI-TOF-TOF mass spectrometry. The results showed that toxin biosynthesis of A. catenella occurred within a defined time frame in the G1 phase of the cell cycle. Proteomic analysis indicated that 102 protein spots altered significantly in abundance (P < 0.05), and 53 proteins were identified using database searching. These proteins were involved in a variety of biological processes, i.e., protein modification and biosynthesis, metabolism, cell division, oxidative stress, transport, signal transduction, and translation. Among them, nine proteins with known functions in paralytic shellfish toxin-producing cyanobacteria, i.e., methionine S-adenosyltransferase, chloroplast ferredoxin-NADP+ reductase, S-adenosylhomocysteinase, adenosylhomocysteinase, ornithine carbamoyltransferase, inorganic pyrophosphatase, sulfotransferase (similar to), alcohol dehydrogenase and arginine deiminase, varied significantly at different toxin biosynthesis stages and formed an interaction network, indicating that they might be involved in toxin biosynthesis in A. catenella. This study is the first step in the dissection of the behavior of the A. catenella proteome during different toxin biosynthesis stages and provides new insights into toxin biosynthesis in dinoflagellates.

Direct measurement of dissolved N2 and denitrification along a subtropical river-estuary gradient, China.

The spatial pattern and seasonal variation of denitrification were investigated during 2010-2011 in the Jiulong River Estuary (JRE) in southeast China. Dissolved N2 was directly measured by changes in the N2:Ar ratio. The results showed that excess dissolved N2 ranged from -9.9 to 76.4 µmol L⁻¹. Tidal mixing leads to a seaward decline of dissolved gaseous concentrations and water-air fluxes along the river-estuary gradient. Denitrification at freshwater sites varied between seasons, associated with changes in N input and water temperature. The denitrification process was controlled by the nitrate level at freshwater sites, and the excess dissolved N2 observed at the tidal zone largely originated from upstream water transport. Compared to other estuaries, JRE has a relative low gaseous removal efficiency (E(d)=12% of [DIN]; annual N removal=24% of DIN load), a fact ascribed to strong tidal mixing, coarse-textured sediment with shallow depth before bedrock and high riverine DIN input.

Detecting the dynamic linkage between landscape characteristics and water quality in a subtropical coastal watershed, Southeast China.

Geospatial analysis and statistical analysis are coupled in this study to determine the dynamic linkage between landscape characteristics and water quality for the years 1996, 2002, and 2007 in a subtropical coastal watershed of Southeast China. The landscape characteristics include Percent of Built (%BL), Percent of Agriculture, Percent of Natural, Patch Density and Shannon's Diversity Index (SHDI), with water quality expressed in terms of COD(Mn) and NH(4)(+)-N. The %BL was consistently positively correlated with NH(4)(+)-N and COD(Mn) at time three points. SHDI is significantly positively correlated with COD(Mn) in 2002. The relationship between NH(4)(+)-N, COD(Mn) and landscape variables in the wet precipitation year 2007 is stronger, with R(2) = 0.892, than that in the dry precipitation years 1996 and 2002, which had R(2) values of 0.712 and 0.455, respectively. Two empirical regression models constructed in this study proved more suitable for predicting COD(Mn) than for predicting NH(4)(+)-N concentration in the unmonitored watersheds that do not have wastewater treatment plants. The calibrated regression equations have a better predictive ability over space within the wet precipitation year of 2007 than over time during the dry precipitation years from 1996 to 2002. Results show clearly that climatic variability influences the linkage of water quality-landscape characteristics and the fit of empirical regression models.

Quantitative proteomic analysis of differentially expressed proteins in the toxicity-lost mutant of Alexandrium catenella (Dinophyceae) in the exponential phase.

Alexandrium catenella is a widely spread dinoflagellate species which can produce potent neurotoxins and result in paralytic shellfish poisoning. To date, the molecular mechanisms regulating toxin biosynthesis remain unclear. This study compared protein profiles of a toxicity-lost mutant of A. catenella, ACHK-NT and its wild-type, ACHK-T in the exponential phase, using two dimensional differential gel electrophoresis and MALDI-TOF-TOF mass spectrometry. Morphological analysis showed that both subcultures were morphologically identical with the distinctive taxonomic characteristics of A. catenella. Sequence analyses of ITS1, 5.8S, ITS2 and 18S demonstrated that the mutant and wild subcultures were genetically identical for these markers. 90 differentially expressed protein spots were identified from ACHK-NT, of which 34 were down-regulated and 56 were up-regulated. Using a multilayered strategy for de novo protein sequence analysis, 67 proteins assigned to different functional categories were identified. Among them, 25 involved in bioluminescence, secondary metabolite biosynthesis, protein modification and toxin biosynthesis were down-regulated, while 42 participating in carbon fixation, stress response, transporter and protein folding were up-regulated. This study indicated that the strengthening of certain biological processes coupled with the depression of essential reactions upstream or downstream of the toxin biosynthetic pathway might have blocked toxin production and resulted in the loss of toxicity in the mutant A. catenella.

Effect of storm events on riverine nitrogen dynamics in a subtropical watershed, southeastern China.

Rain storms are predicted to increase in the subtropical region due to climate change. However, the effects of storm events on riverine nitrogen (N) dynamics are poorly understood. In this study, the riverine N dynamics and storm effects in a large subtropical river (North Jiulong River, southeastern China) were investigated through continuous sampling of two storm events which occurred in June 2010 and June 2011. The results disclosed a strong linkage between N dynamics and hydrological controls and watershed characteristics. The extreme storm in June 2010 resulted in more fluctuations in N concentrations, loads, and composition, compared with the moderate storm in June 2011. There were contrasting patterns (e.g., the hysteresis effect) between nitrate and ammonium behavior in storm runoff, reflecting their different supply source and transport mechanism. Overall, nitrate supply originated from subsurface runoff and was dominated by within-channel mobilization, while ammonium was mainly from over-land sources and flushed by surface runoff. Extreme storm runoff (2010) caused a four-fold increase in dissolved inorganic N fluxes (DIN), with a greater fraction of ammonium (up to 30% of DIN) compared with the moderate storm and background flow condition (less than 15%). Storm-driven sharp increases of N loads and changes in nutrient stoichiometry (more ammonium) might have been connected with algal blooms in the adjacent estuary and Xiamen Bay. Combined with the background flow measurement of N gradients along the main river and a stream together with anthropogenic N load information, the interactive effect of hydrological and biogeochemical process on riverine N was preliminarily revealed. Current results suggested that storm runoff N was controlled by rainfall, hydrological condition, antecedent soil moisture, spatial variability of land-based N source, and damming. These findings could be used as a reference for future water quality monitoring programs and the development of a pollution mitigation strategy.

The role of cytochrome P4501A activity inhibition in three- to five-ringed polycyclic aromatic hydrocarbons embryotoxicity of marine medaka (Oryzias melastigma).

The mode of action of PAHs that causes fish developmental malformations is unclear. The embryotoxicity of marine medaka (Oryzias melastigma) was investigated after individual exposure to three- to five-ring PAHs Phe, Py, and BaP or co-exposure with α-ANF for 18 days. We found that the relationships between EROD induction and developmental deformities of embryos showed a various pattern under different exposure scenarios of Phe, Py, and BaP, which suggested possibly different modes of action in determining the developmental toxicities. As for co-exposure scenarios of each PAH combined with ANF, it showed potentially synergistic effects. The inhibited CYP1A mediated enzyme activity by ANF after co-exposure did not effectively alleviate developmental toxicity of embryo. It showed potentially synergistic effects after co-exposure of marine fish embryos to CYP1A inhibitors and PAH-type CYP1A inducers. Heart deformities in the early life stages of marine medaka were recommended as a biomarker for indicating the extent of PAH pollution.

Seasonal variation for the ratio of BaP to BeP at different sites in Great Xiamen Bay.

From March 2008 to February 2009, PM(10) samples were collected and analyzed for polycyclic aromatic hydrocarbons (PAHs) at eight sampling sites in Great Xiamen Bay, China. Analyses of the seasonal and spatial variations of these compounds revealed the following results. Significantly high levels of PAHs were found in the winter compared to the summer, sometimes exceeding 100 ng m(-3), and the spatial variations were influenced most by the sampling site surroundings. Composition profiles of PAHs of an urban and a rural site were shown to be very similar with a positive correlation coefficient larger than 0.9 at the 0.01 level of significance for the same season. Diagnostic ratios, together with principal component and multiple linear regression analysis, showed that more PAHs were from grass/wood/coal combustion in winter than in other seasons. The ratios of benzo[a]pyrene to benzo[e]pyrene (BaP-BeP) in winter and fall were 0.6-1.7 times higher than those in spring and summer, suggesting the importance of local emissions of PAHs. The BaP-BeP ratios in Kinmen were generally lower than those in Xiamen, indicating that the aging degree of PAHs was higher in Kinmen than in Xiamen. The external input of PAHs from upwind urban and industrial areas was one of the key factors causing high levels of PAHs in PM(10) in Great Xiamen Bay in winter.

Quantitative proteomic analysis of okadaic acid treated mouse small intestines reveals differentially expressed proteins involved in diarrhetic shellfish poisoning.

Okadaic acid (OA) is a principal diarrhetic shellfish poisoning toxin produced by marine dinoflagellates. This study compared protein profiles of mice small intestines at four time points (0, 3, 6 and 24 h) after a single oral administration of 750 µg/kg OA, and identified the differentially expressed proteins using 2-D DIGE and MALDI-TOF-TOF mass spectrometry. The results showed that the toxin content of the intestines reached its peak 3h after oral administration and then decreased rapidly. OA remarkably inhibited the intestinal PP activity but it recovered to the normal levels within 6 to 24 h. Electron microscope revealed the collapse of the villous architecture and the intestinal microvilli fell off at 3 h, but were repaired within 24h. Notable damage to the intestinal ultrastructure was observed after oral administration. Comparison of the small intestine protein profiles at four time points revealed that 58 proteins were remarkably altered in abundance, and these proteins were involved in macromolecular metabolism, cytoskeleton reorganization, signal transduction, molecular chaperoning and oxidative stress, suggesting that OA toxicity in mouse intestines was complex and diverse, and that multiple proteins other than PP were involved in the diarrhetic process. Villin 1 and hnRNP F might be the key triggers inducing diarrhea in the mouse small intestines.