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An understanding of regulating factors and early warning of Ulva prolifera biomass increase may reduce harm or prevent bloom disasters in the Yellow Sea. We investigated the minimum nutrient concentration and light-limiting depth (Zlim) for the growth of floating U. prolifera thalli. Bioavailable dissolved nitrogen (BDN) concentrations in most parts of the study area were almost always higher than the minimum N concentrations required for the growth of floating thalli, indicating no N limitation for the growth of floating thalli. However, the minimum N concentration required for the development of germlings into thalli was higher than BDN in the majority of the area north of 35°N. This indicated that germlings floating out of Subei Shoal were unable to grow into thalli because of N limitation. The minimum P concentration required for germling development was higher than the total dissolved P north of 35°N. This suggested that P limitation occurred for germlings floating out of Subei Shoal. The Zlim for the floating thalli was U. prolifera drifted northward following different trajectories. The predicted AcMp values in 2017, 2010, and 2009 were close to the ratio of the coverage area from remote sensing data. Such a grid pattern facilitates quick decisions in disaster prevention and reduction.

It's a new perspective to explore the influences of chromophoric dissolved organic matter (CDOM) components and environmental factors on the removal of sulfisoxazole (SIX) from the water matrix. Reactive intermediates (RIs) trapping experiments demonstrated that excited triplet-state CDOM (

Dissolved heavy metal pollution in the ocean is becoming an environmental concern. Their distribution patterns are complex and influenced by multiple factors in the coastal ocean. Therefore, more investigations are needed to understand their behavior in the seawater. This study systematically investigated the distribution of Cu, Pb, Cd, As, Zn and seawater properties in the surface and bottom water off the Yangtze River Estuary, East China Sea in spring, summer and autumn, 2019. The results showed significant spatiotemporal distribution that three-zone-pattern of estuary, nearshore, and offshore can be divided. While sources, hydrodynamics, biological uptake and sediment resuspension affected the overall distribution, dissolved oxygen and pH dominantly influenced the estuary and offshore respectively, with more complex factors in the nearshore. Low ecological risks were assessed during the study, but global warming, ocean acidification and hypoxia are essential concerns to understand the biogeochemistry of dissolved heavy metals in the ocean.

The components, sources, and seasonal and spatial changes of fluorescent dissolved organic matter (FDOM) in the continental shelf area of the East China Sea (ECS), were determined by excitation and...

The Ulva prolifera green tides in the Yellow Sea, China, which have been occurring since 2007, are a serious environmental problem attracting worldwide attention. Despite extensive research, the outbreak mechanisms have not been fully understood. Comprehensive analysis of anthropogenic and natural biotic and abiotic factors reveals that human activities, regional physicochemical conditions and algal physiological characteristics as well as ocean warming and biological interactions (with microorganism or other macroalgae) are closely related to the occurrence of green tides. Dynamics of these factors and their interactions could explain why green tides suddenly occurred in 2007 and decreased abruptly in 2017. Moreover, the consequence of green tides is serious. The decay of macroalgal biomass could result in hypoxia and acidification, possibly induce red tide and even have a long-lasting impact on coastal carbon cycles and the ecosystem. Accordingly, corresponding countermeasures have been proposed in our study for future reference in ecosystem management strategies and sustainable development policy.

Large-scale floating green tides in the Southern Yellow Sea (SYS) caused by the macroalgal species Ulva prolifera have been recurring for 13 years and have become one of the greatest marine ecological disasters in the world. In this study, we attempt to explore the development pattern of green tides and find its key environmental influencing factors. The satellite remote sensing data of the development process of green tides fit the logistic growth curve (R2 = 0.93, P

Dissolved organic nitrogen (DON) from terrestrial input exacerbates eutrophication and induces harmful algal blooms. We investigated the effects of hydrophilic (Hic) and low molecular weight (LMW) DON on the phytoplankton community in Jiaozhou Bay during autumn (October 2017) and spring (May 2018). Our results showed DON additions significantly increased algal growth while decreasing community biodiversity and provide a competitive advantage for Skeletonema costatum. These situations were further intensified by increasing temperature in autumn. Additionally, Hic DON had a higher bioavailability than LMW DON. Based on emission-excitation matrix spectra, we identified protein-like components as the main components of Hic DON whereas humus-like components were the principal components of LMW. Correlation analysis confirmed a positive correlation between DON bioavailability and protein-like components. Therefore, our results indicate DON from terrestrial input disrupts the structural stability of the phytoplankton community and increases the risk of harmful algal blooms, which in turn threaten coastal ecosystems.

We investigated the remineralization of sedimentary organic carbon (SOC) at 12 sites in East China Sea mobile-muds (ECSMMs) and South Yellow Sea central mud deposits (SYSMDs) - using a time-sequence sediment incubation experiment. We examined pore-water dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), fluorescent dissolved organic matter (FDOM), dissolved inorganic nitrogen (DIN) nutrients (NH4+, NO3−, and NO2−), redox sensitive elements (Fe2+ and Mn2+), and major anions (SO42− and Cl−) in incubated sediments, to better constrain controlling mechanisms of SOC remineralization under different sedimentary regimes. Lower DIC production rates in SYSMDs (2.36–3.13 mmol m−2 d−1) than those in ECSMMs (2.94–13.5 mmol m−2 d−1), were mainly attributed to cold bottom water masses and a relatively stable sedimentary environment in SYS. Higher DIC production rates were observed mostly at offshore sites of ECSMMs that had relatively enriched 13C of SOC - which indicated preferential degradation of labile SOC of marine origin. When compared with tropical mobile-muds, higher bottom-water temperatures, thicker mobile-muds, and large inputs of reactive terrestrial OC resulted in more intense remineralization of SOC in Amazon mobile-muds than in ECSMMs. Lower ratios of DOC/DIC production rates in ECSMMs (0.11–0.72) were likely indicative of efficient transformation of OC, and largely due to sulfate reduction. A rapid increase in marine protein-like FDOM components during the incubation indicated that less stable marine SOC was preferentially converted to DOC - and then to DIC. Our SOC budget indicates that 16.8% of SOC was decomposed in sediments of ECSMMs, but only about 5.4% of SOC was decomposed in SYSMDs, suggesting lower SOC preservation efficiency in mobile-muds than distal muds.

The largest-scale green tides in the world caused by Ulva prolifera have been recurring annually in the Southern Yellow Sea since 2007. In this study, spatio-temporal variations of green tides and nutrients were investigated in the spring and summer of 2017, and the roles of different nutrients in the development of green tides are discussed. The results showed that the development of green tides could be divided into two parts according to the distinct growth phases of green tides: (1) the development area (DA), which was located south of 35°N and characterised by the quick expansion of green tide and high-content nutrient; (2) the accumulation area (AA), which was located north of 35°N and characterised by high U. prolifera coverage area and low-content inorganic nutrients. Through calculation of nutrient reductions, we found that DA provided 96% of nitrogen and 87% of phosphorus for the development of green tides in 2017, and the dominant nutrient species were dissolved inorganic nitrogen and dissolved organic phosphorus. Regarding AA, the dominant nitrogen component was dissolved organic nitrogen. Thus, we conclude that reducing the level of nutrient input in order to alleviate the eutrophication of seawater in the Jiangsu coastal area may be an important measure for reducing the scale of green tides.

Seaweeds are one of the largest producers of biomass in the marine environment. It has been well known that marine algae, especially brown algae was a rich source of biogenic compounds with antifouling potential that could be ideal alternatives of tributyltin (TBT). In this paper, antifouling potential of the brown algae Laminaria ‘sanhai’ was explored. Firstly, the dried alga was extracted and the antialgal and antilarval activities were investigated. The EC50 and LC50 values of crude extract of Laminaria ‘sanhai’ against diatom (Skeletonema costatum) and barnacle larval (Chthamalus challengeri) were 8.9 μg mL−1 and 12.0 μg mL−1 respectively. Then, guided by bioassay, the bioactive substances were isolated by liquid-liquid extraction. The antialgal and antilarval activities of isolated fraction were improved with the EC50 value of 7.4 μg mL−1 against S. costatum and LC50 value of 9.7 μg mL−1 against C. challengeri larvae. Identification by IR, Q-TOFMS and GC-MS of the isolated bioactive substances revealed the abundance of fatty acids. These fatty acids, most with 16, 18 or 20 carbon atoms, contained myristic, hexadecanoic, oleic, linolenic, arachidonic and eicosapentaenoic acids. The results indicated that both the crude extract and the isolated bioactive substances had high antialgal and antilarval activities with no highlighted cytotoxicity which made the brown algae Laminaria ‘sanhai’ a promising source of the environmentally friendly antifoulants.

The indirect photodegradation behaviors of acetaminophen (APAP) were investigated in the presence of four kinds of dissolved organic matter (DOM) and were also assessed in the presence of seawater components and conditions such as salinity, pH, nitrate and bicarbonate. The results showed three important findings: firstly, in the indirect photolysis of APAP, the contributions of 3DOM*, ·OH and 1O2 were >85.0%, 2.3–9.9% and 0.8–2.6% at pH 8.0. Secondly, DOM was divided into four terrestrial humic-like components by Excitation–emission matrix spectroscopy (EEMs) combined with parallel factor analysis (PARAFAC). This study showed a good linearity between DOM fluorescence components and the indirect photodegradation of APAP (R2 = 0.92) and the differences in photodegradation rates of APAP among various DOM solutions were due to the diverse compositions of DOM. Finally, salinity was an important factor influencing the removal of APAP, and the APAP photodegradation rate constants increased from (3.33 ± 0.07) × 10−5 s−1 to (1.25 ± 0.05) × 10−4 s−1 with increasing salinity. The increased pseudo-first-order rate constants for photolysis of APAP with increasing salinity, pH and nitrate were attributed to the enhanced generation of reactive intermediates (RI) and easier reactions between RI and APAP. The increased APAP removal rate constant with increasing bicarbonate was likely ascribed to the yield of ∙CO3−. This is the first report of the roles of DOM components and salinity on the indirect photolysis of APAP. These findings would be essential to predict the photochemical fate of APAP and would also allow for a better understanding of the environmental fate of other phenolic contaminants.

Increasing human activities have caused the accumulation of dissolved organic nitrogen (DON) in the ocean, which can alter dominant coastal phytoplankton species. However, insights into DON's effects on marine phytoplankton growth are insufficient compared with those of dissolved inorganic nitrogen (DIN), especially regarding the role of specific DON components. Therefore, in this study, the effects of the hydrophilic (Hic) and low molecular weight (LMW) components of two anthropogenic DON sources on the growth and bioavailable nitrogen uptake of phytoplankton were studied using in situ cultural experiments conducted in Jiaozhou Bay, China. Animal-derived DON from domestic and livestock breeding showed a higher bioavailability compared with that of vegetal DON derived from agricultural sources, with bioavailable component proportions of 76% ± 4% and 66% ± 3%, respectively. Both forms of DON could be absorbed by Skeletonema costatum, stimulating it to become the dominant species in the mesocosm ecosystem; the hydrophilic components of DON contributed approximately 75% of the uptake of DON by S. costatum. The bioavailability of LMW DON was significantly (p 0.05) lower than that of the Hic DON. The high bioavailability of the Hic DON was mainly associated with its protein-like T1 and T2 components, identified using parallel factor analysis on the excitation-emission-matrix spectra, while the low bioavailability of LMW DON was mainly associated with the humus-like A component. The protein-like T2 components may be directly absorbed by algae, while T1 may be transformed through mineralization and algal absorption. Understanding the impacts of anthropogenic DON and its components on phytoplankton will help improve coastal environmental management. More knowledge of the effect of anthropogenic DON on the phytoplankton community structure in coastal waters should be accumulated in the future.

To realize potential cost savings in coastal monitoring programs and provide timely advice for marine management, there is an urgent need for efficient evaluation tools based on easily measured variables for the rapid and timely assessment of estuarine and offshore eutrophication. In this study, using parallel factor analysis (PARAFAC), principal component analysis (PCA), and discriminant function analysis (DFA) with the trophic index (TRIX) for reference, we developed an approach for rapidly assessing the eutrophication status of coastal waters using easy-to-measure parameters, including chromophoric dissolved organic matter (CDOM), fluorescence excitation–emission matrices, CDOM UV-Vis absorbance, and other water-quality parameters (turbidity, chlorophyll a, and dissolved oxygen). First, we decomposed CDOM excitation-emission matrices (EEMs) by PARAFAC to identify three components. Then, we applied PCA to simplify the complexity of the relationships between the water-quality parameters. Finally, we used the PCA score values as independent variables in DFA to develop a eutrophication assessment model. The developed model yielded classification accuracy rates of 97.1%, 80.5%, 90.3%, and 89.1% for good, moderate, and poor water qualities, and for the overall data sets, respectively. Our results suggest that these easy-to-measure parameters could be used to develop a simple approach for rapid in-situ assessment and monitoring of the eutrophication of estuarine and offshore areas.

There is an urgent need to develop efficient evaluation tools that use easily measured variables to make rapid and timely eutrophication assessments, which are important for marine health management, and to implement eutrophication monitoring programs. In this study, an approach for rapidly assessing the eutrophication status of coastal waters with three easily measured parameters (turbidity, chlorophyll a and dissolved oxygen) was developed by the grid search (GS) optimized support vector machine (SVM), with trophic index TRIX classification results as the reference. With the optimized penalty parameter C =64 and the kernel parameter γ =1, the classification accuracy rates reached 89.3% for the training data, 88.3% for the cross-validation, and 88.5% for the validation dataset. Because the developed approach only used three easy-to-measure variables, its application could facilitate the rapid assessment of the eutrophication status of coastal waters, resulting in potential cost savings in marine monitoring programs and assisting in the provision of timely advice for marine management.

Compositions and concentrations of chromophoric dissolved organic matter (CDOM) have been determined in the Bohai Sea (BS) and the Yellow Sea (YS) in the summer and autumn in 2013 by excitation and emission matrix spectroscopy (EEMs) and parallel factor analysis (PARAFAC). The PARAFAC model identified three humic-like components (C1, C2, and C3) and one protein-like component (C4). CDOM exhibited higher fluorescence intensities in the coastal areas in both the summer and autumn. However, its distribution patterns were different in the two seasons. Based on spatial and seasonal distributions of four components, as well as correlations with salinity, chlorophyll a (Chl-a), and apparent oxygen utilization (AOU), the following assignments were made. The C1, C2, and C3 components were mainly dominated by terrestrial inputs and influenced by the primary productivity of phytoplankton in the summer as well. C4 was assigned to terrestrial and autochthonous origins and most likely represented a biologically labile component. Terrestrial inputs were the dominant source of CDOM in the BS and YS. The humification index (HIX) and biological index (BIX) suggested that CDOM in the BS was more stable than that in the YS, which had an increase in autochthonous production, and in the summer, CDOM was less stable with a higher CDOM autochthonous production compared with that in the autumn.

Seawater samples were collected from April 6 to September 6, 2017 in the Southern Yellow Sea, China where green tides often occurred, and analyzed for nutrients, dissolved organic carbon (DOC), and fluorescent dissolved organic matter (FDOM). The DOC concentrations increased significantly in the green tide areas by approximately 1.2 times compared to those in the non-green tide areas. From the large-scale outbreak to the complete dissipation of the green tide, the fluorescence intensities of the four FDOM fluorescent components identified in the green tide areas were significantly higher than those in the non-green tide areas. During the extinction period, the fluorescence intensities of the three humus-like components and one protein-like component were approximately 1.8 and 1.3 times higher than those in the non-green tide areas, respectively. These findings suggested that the outbreak of green tide could release DOM into water and affect the biogeochemical cycle in green tide regions.

One of the largest “green tide” (Ulva prolifera) outbreaks in the world has occurred every year from 2007 to present in the Southern Yellow Sea, China. Currently, the coastal area around Jiangsu Province (Subei Shoal region) is thought to be the origination point of these giant green tide blooms. The combination of high nutrient demand but low river discharge and other inputs suggests that there is a significant flux of submarine groundwater discharge (SGD) in this area. By using a radium mass balance model, we estimated the SGD flux in the area to be (0.7–1.4) × 109 m3 d−1 (6.1–12 cm d−1), at the high end of SGD fluxes worldwide. Geographically, Subei Shoal is less than 5% of the entire Southern Yellow Sea area, while our calculated SGD flux just for the shoal area is ~3 times larger than previously documented for the whole Southern Yellow Sea. Therefore, Subei Shoal may be considered a SGD hotspot that plays an important role in SGD associated material fluxes. Compared to inputs from local rivers, atmospheric deposition, and anthropogenic activities, SGD-derived nutrients are the main source term that can support the growth of macroalgae. We specifically highlight that this type of areas that are shallow, intensively mixed, anthropogenically polluted, sandy or muddy with heavy bio-irrigation, may have a higher risk of suffering harmful ecological problems, even with limited terrestrial runoff.

The presence of pharmaceuticals and personal care products in coastal waters has caused concern over the past decade. Sulfadiazine (SD) is a very common antibiotic widely used as human and fishery medicine, and dissolved organic matter (DOM) plays a significant role in the indirect photodegradation of SD; however, the influence of DOM compositions on SD indirect photodegradation is poorly understood. The roles of reactive intermediates (RIs) in the indirect photolysis of SD were assessed in this study. The reactive triplet states of DOM (3DOM∗) played a major role, whereas HO· and 1O2 played insignificant roles. DOM was divided into four components using excitation-emission matrix spectroscopy combined with parallel factor analysis. The components included three allochthonous humic-like components and one autochthonous humic-like component. The allochthonous humic-like components contributed more to RIs generation and SD indirect photolysis than the autochthonous humic-like component. A significant relationship between the indirect photodegradation of SD and the decay of DOM fluorescent components was found (correlation coefficient, 0.99), and the different indirect photodegradation of SD in various DOM solutions might be ascribed to the different components of DOM. The indirect photolysis rate of SD first increased and then decreased with increasing pH. SD photolysis was enhanced by low salinity but remained stable at high salinity. The increased carbonate concentration inhibited SD photolysis, whereas nitrate showed almost no effect in this study.

Sulfonamides (SAs) are ubiquitous antibiotics that are increasingly detected in the aquatic environment, and may cause potential harm to the environment and humans. Indirect photodegradation has been considered to be a promising natural degradation process for antibiotics in the environment. Chromophoric dissolved organic matter (CDOM) is an important participant in the indirect photodegradation of antibiotics. Indirect photodegradation of sulfathiazole (ST) and sulfamerazine (SM) were studied in the presence of CDOM and marine factors (salinity, pH, nitrate (NO3-) and bicarbonate (HCO3-)) to simulate photodegradation of these compounds in the coastal seawater environment. The main findings are as follows. First, the indirect photodegradation rates of ST and SM in the presence of CDOM were significantly increased and followed the pseudofirst order kinetics. Second, 1O2 played a critical role in the indirect photodegradation of ST and its contribution rate was 54.2%; 3CDOM⁎ performed similarly in the case of SM with a 58.0% contribution rate. Third, CDOM was divided into four fluorescent components by excitation-emission matrix spectroscopy and parallel factor analysis (EEMs-PARAFAC), including three exogenous components and an autochthonous component. The exogenous components with high molecular weight and higher number of aromatic groups played a decisive role in the indirect photodegradation of ST and SM due to their ability to generate higher levels of reactive intermediates (RIs). Finally, seawater factors (salinity, pH, NO3- and HCO3-) influenced the indirect photodegradation of ST and SM by influencing the steady-state concentrations of RIs. This report is the first study of indirect photodegradation of ST and SM from the perspective of the CDOM components and simulated coastal waters.

This paper presents an initial inquiry into model-based numeric nitrogen and phosphorus criteria for estuaries based on stressor-response models between nutrients and algal biomass (Chl-a concentration) and further studies the effect of salinity (S) on nutrient criteria. Field data collection and associated indoor modeling were conducted in Daliaohe Estuary. Dissolved inorganic nitrogen (DIN), total nitrogen (TN), phosphate ( P O 4 3 − ) and total phosphorus (TP) eco-criteria of Daliaohe Estuary in China were calculated at salinities of 15, 25 and 31. The results suggested that the variation in S had significant influence on the DIN and TN eco-criteria and no obvious effect on the P O 4 3 − and TP eco-criteria. The values of DIN and TN eco-criteria increased with either higher or lower salinity concentrations, and were strongly linked to the effects of salinity on algal nutrient absorption and utilization, growth, metabolism, and osmotic pressure.

With the global ban on the application of organotin-based marine coatings by the International Maritime Organization, the development of environmentally friendly, low-toxic and nontoxic antifouling compounds for marine industries has become an urgent need. Marine microorganisms have been considered as a potential source of natural antifoulants. In this study, the antifouling potential of marine dinoflagellate Amphidinium carterae, the toxic and red-tide microalgae, was investigated. We performed a series of operations to extract the bioactive substances from Amphidinium carterae and tested their antialgal and antilarval activities. The crude extract of Amphidinium carterae showed significant antialgal activity and the EC50 value against Skeletonema costatum was 55.4 μg mL−1. After purification, the isolated bioactive substances (the organic extract C) exhibited much higher antialgal and antilarval activities with EC50 of 12.9 μg mL−1 against Skeletonema costatum and LC50 of 15.1 μg mL−1 against Amphibalanus amphitrite larvae. Subsequently, IR, Q-TOFMS, and GC-MS were utilized for the structural elucidation of the bioactive compounds, and a series of unsaturated and saturated 16- to 22-carbon fatty acids were detected. The data suggested the bioactive compounds isolated from Amphidinium carterae exhibited a significant inhibiting effect against the diatom Skeletonema costatum and Amphibalanus amphitrite larvae, and could be substitutes for persistent, toxic antifouling compounds.

In this study, the extraction, identification, and antialgal activity of toxic organic substances from decaying green alga Ulva prolifera, a disaster-causing alga on green tides in the Yellow Sea, were investigated. The toxic organic substances of U. prolifera were isolated by a sequence of procedures, namely, liquid-liquid extraction (LLE), silica gel chromatography column separation (SGCC), C18 solid phase extraction (C18 SPE), and acid-alkali separation (AAS) and their antialgal activities were tested against diatom Skeletonema costatum. The results showed that the 96h-EC50 value in each procedure was 57.00 mg•L−1, 12.14 mg•L−1, 11.70 mg•L−1, and 6.31 mg•L−1 in turn. Additionally, the initial (ethyl acetate extract in LLE) and final (Organic phase A in AAS) yield of toxic organics were 318 mg•kg−1 and 9 mg•kg−1 (the wet weight of U. prolifera). The final active fractions were preliminary identified as five 16- and 18-carbon fatty acids and four enols using GC–MS. The study may further evaluate the effect of bioactive substances on marine life after U. prolifera green tides bloom.

An unprecedented bi-macroalgal bloom caused by Ulva prolifera and Sargassum horneri occurred from spring to summer of 2017 in the western Yellow Sea (YS) of China, where annual large-scale green tides have prevailed for a decade. The distinct genesis and blooming dynamics of the two seaweed species were detected and described. Unlike the consistent raft-origin of the floating Ulva biomass, the massive pelagic S. horneri was derived from multiple sources (residual seaweeds from the previous winter bloom and those drifting from offshore water in the south). The scale of the green tide in 2017 was found smaller than the previous four years. We then discussed a number of hypotheses attributing to this reduction, including reduced epiphytic green algae from aquaculture rafts and the influences of the massive pelagic S. horneri. However, further research is needed to identify the origin of the pelagic S. horneri in the western YS and any affiliations with the benthic populations, and to elucidate the interactions of this species with the annual green tides and the ensuing consequences.

Samples of chromophoric dissolved organic matter (CDOM) from the Southern Yellow Sea (SYS) and the East China Sea (ECS) were evaluated by fluorescent Excitation Emission Matrix (EEM) combined with Parallel Factorial Analysis (PARAFAC). Three terrestrial humic-like components (C1, C2 and C3) and one autochthonous protein-like component (C4) were identified. As for seasonal variations, CDOM displayed the following order on the whole: summer>spring>autumn. The C1, C2 and C3 components were mainly dominated by terrestrial inputs and their spatial distributions and temporal variations also can be influenced by primary productivity of phytoplankton, microbial activities and photobleaching. C4 was produced by phytoplankton and microorganisms and consumed by marine bacteria, and besides its distribution was attributed to the influence of riverine inputs. Terrestrial inputs were the dominant sources of CDOM in the SYS and ECS.

The southern Changjiang River Estuary has attracted considerable attention from marine scientists because it is a highly biologically active area and is biogeochemically significant. Moreover, land-ocean interactions strongly impact the estuary, and harmful algal blooms (HABs) frequently occur in the area. In October 2010 and May 2011, water samples of chromophoric dissolved organic matter (CDOM) were collected from the southern Changjiang River Estuary. Parallel factor analysis (PARAFAC) was used to assess the samples’ CDOM composition using excitation-emission matrix (EEM) spectroscopy. Four components were identified: three were humic-like (C1, C2 and C3) and one was protein-like (C4). Analysis based on spatial and seasonal distributions, as well as relationships with salinity, Chl a and apparent oxygen utilization (AOU), revealed that terrestrial inputs had the most significant effect on the three humic-like Components C1, C2 and C3 in autumn. In spring, microbial processes and phytoplankton blooms were also important factors that impacted the three components. The protein-like Component C4 had autochthonous and allochthonous origins and likely represented a biologically labile component. CDOM in the southern Changjiang River Estuary was mostly affected by terrestrial inputs. Microbial processes and phytoplankton blooms were also important sources of CDOM, especially in spring. The fluorescence intensities of the four components were significantly higher in spring than in autumn. On average, C1, C2, C3, C4 and the total fluorescence intensity (TFI) in the surface, middle and bottom layers increased by 123%–242%, 105%–195%, 167%–665%, 483%–567% and 184%–245% in spring than in autumn, respectively. This finding corresponded with a Chl a concentration that was 16–20 times higher in spring than in autumn and an AOU that was two to four times lower in spring than in autumn. The humification index (HIX) was lower in spring that in autumn, and the fluorescence index (FI) was higher in spring than in autumn. This result indicated that the CDOM was labile and the biological activity was intense in spring.

The feasibility of using fluorescence excitation-emission matrix (EEM) along with parallel factor analysis (PARAFAC) and nonnegative least squares (NNLS) method for the differentiation of phytoplankton taxonomic groups was investigated. Forty-one phytoplankton species belonging to 28 genera of five divisions were studied. First, the PARAFAC model was applied to EEMs, and 15 fluorescence components were generated. Second, 15 fluorescence components were found to have a strong discriminating capability based on Bayesian discriminant analysis (BDA). Third, all spectra of the fluorescence component compositions for the 41 phytoplankton species were spectrographically sorted into 61 reference spectra using hierarchical cluster analysis (HCA), and then, the reference spectra were used to establish a database. Finally, the phytoplankton taxonomic groups was differentiated by the reference spectra database using the NNLS method. The five phytoplankton groups were differentiated with the correct discrimination ratios (CDRs) of 100% for single-species samples at the division level. The CDRs for the mixtures were above 91% for the dominant phytoplankton species and above 73% for the subdominant phytoplankton species. Sixteen of the 85 field samples collected from the Changjiang River estuary were analyzed by both HPLC-CHEMTAX and the fluorometric technique developed. The results of both methods reveal that Bacillariophyta was the dominant algal group in these 16 samples and that the subdominant algal groups comprised Dinophyta, Chlorophyta and Cryptophyta. The differentiation results by the fluorometric technique were in good agreement with those from HPLC-CHEMTAX. The results indicate that the fluorometric technique could differentiate algal taxonomic groups accurately at the division level.

An in vivo three-dimensional fluorescence method for the determination of algae community structure was developed by parallel factor analysis (PARAFAC) and CHEMTAX. The PARAFAC model was applied to fluorescence excitation-emission matrix (EEM) of 60 algae species belonging to five divisions and 11 fluorescent components were identified according to the residual sum of squares and specificity of the composition profiles of fluorescent. By the 11 fluorescent components, the algae species at different growth stages were classified correctly at the division level using Bayesian discriminant analysis (BDA). Then the reference fluorescent component ratio matrix was constructed for CHEMTAX, and the EEM-PARAFAC-CHEMTAX method was developed to differentiate algae taxonomic groups. The correct discrimination ratios (CDRs) when the fluorometric method was used for single-species samples were 100% at the division level, except for Bacillariophyta with a CDR of 95.6%. The CDRs for the mixtures were above 94.0% for the dominant algae species and above 87.0% for the subdominant algae species. However, the CDRs of the subdominant algae species were too low to be unreliable when the relative abundance estimated was less than 15.0%. The fluorometric method was tested using the samples from the Jiaozhou Bay and the mesocosm experiments in the Xiaomai Island Bay in August 2007. The discrimination results of the dominant algae groups agreed with microscopy cell counts, as well as the subdominant algae groups of which the estimated relative abundance was above 15.0%. This technique would be of great aid when low-cost and rapid analysis is needed for samples in a large batch. The fluorometric technique has the ability to correctly identify dominant species with proper abundance both in vivo and in situ.

The ecotoxicological effects of Ciprofloxacin hydrochloride (CIP) were tested on population densities of plankton assemblages consisting of two algae (Isochrysis galbana and Platymonas subcordiformis) and a rotifer (Brachionus plicatilis). The I. galbana showed a significant decrease in densities when concentrations of CIP were above 2.0 mg L−1 in single-species tests, while P. subcordiformis and B. plicatilis were stable in densities when CIP were less than10.0 mg L−1. The equilibrium densities of I. galbana in community test increased with CIP concentrations after falling to a trough at 5.0 mg L−1, showed a completely different pattern of P. subcordiformis which decreased with CIP concentrations after reaching a peak at 30.0 mg L−1. The observed beneficial effect was a result of interspecies interactions of trophic cascade that buffered for more severe direct effects of toxicants. The community test-based NOEC of CIP (2.0 mg L−1), embodying the indirect effects, was different from the extrapolated one derived by single-species tests (0.5 mg L−1), but all lacked confidence interval. A CIP threshold concentration of obvious relevance to ecological interaction was calculated with a simplified plankton ecological model, achieving a value of 1.26 mg L−1 with a 95% bootstrapping confidence interval from 1.18 to 1.31 mg L−1.

Samples of chromophoric dissolved organic matter (CDOM) that were collected from the southern Yellow Sea (SYS) in spring (March in 2011) and autumn (October in 2011) were analyzed by excitation–emission matrix spectroscopy (EEMs) in combination with parallel factor analysis (PARAFAC). This method identified three terrestrial humic-like (C1, C2 and C3) and one protein-like (C4) substances. The distribution patterns of the four components were different in spring and autumn. The impact of the circulation of the Yellow Sea Warm Current in spring and the Yellow Sea Cold Water Mass in autumn in the central Yellow Sea (YS) could be important physical factors in explaining the variability of CDOM in seasonal patterns. The contributions of the humic-like components C1 and C2 increased from 33% and 12% (in spring) to 35% and 15% (in autumn) and that of the protein-like component C4 decreased from 20% (in spring) to 15% (in autumn), the contributions of C3 was not changed between the two seasons. Based on spatial and seasonal distributions, as well as correlations with salinity, the following assignments were made. The two terrestrial humic-like components C1 and C2 were assigned to a terrestrial origin. The other terrestrial humic-like component C3 was assigned to terrestrial and autochthonous origins. The protein-like component C4 was assigned to a combination of autochthonous production and terrestrial sources and most likely represented a biologically labile component. The lower HIX and higher FI in spring indicated CDOM was less stable and biological activity was higher than that in autumn. These results indicated that the CDOM in the SYS was primarily affected by terrestrial inputs, microbial processes and primary productivity of phytoplankton were also important sources.

Marine microorganisms are a new source of natural antifouling compounds. In this study, two bacterial strains, Kytococcus sedentarius QDG-B506 and Bacillus cereus QDG-B509, were isolated from a marine biofilm and identified. The bacteria fermentation broth could exert inhibitory effects on the growth of Skeletonema costatum and barnacle larvae. A procedure was employed to extract and identify the antifouling compounds. Firstly, a toxicity test was conducted by graduated pH and liquid-liquid extraction to determine the optimal extraction conditions. The best extraction conditions were found to be pH 2 and 100% petroleum ether. The EC 50 value of the crude extract of K. sedentarius against the test microalgae was 236.7 ± 14.08 μg mL−1, and that of B. cereus was 290.6 ± 27.11 μg mL−1. Secondly, HLB SPE columns were used to purify the two crude extracts. After purification, the antifouling activities of the two extracts significantly increased: the EC 50 of the K. sedentarius extract against the test microalgae was 86.4 ± 3.71 μg mL−1, and that of B. cereus was 92.6 ± 1.47 μg mL−1. These results suggest that the metabolites produced by the two bacterial strains are with high antifouling activities and they should be fatty acid compounds. Lastly, GC-MS was used for the structural elucidation of the compounds. The results show that the antifouling compounds produced by the two bacterial strains are myristic, palmitic and octadecanoic acids.

Nutrient pollution and algal blooms in coastal waters have long been a major concern, and understanding the response of algae to nutrient dynamics is thus essential. The minimum concentration under which Ulva prolifera will not grow, estimated from a nutrient-alga coupling model developed in this study, was 6.5 μmol L−1 for nitrate and 0.27 μmol L−1 for phosphate. The model was parameterized with cultural experiments to examine the effects of nitrate and phosphate on the growth of Ulva prolifera and the development of green tide. The cultural experiments showed that flux of nitrate absorbed by Ulva prolifera increased significantly with the concentration of nitrate or phosphate, which followed the Michaelis-Menten equation, while the flux of phosphate linearly increased with its concentrations. Nitrate concentrations at >25 μmol L−1 had little influence on the absorption of phosphate, but compensating absorption of phosphate occurred when the nitrate concentration was below 15 μmol L−1. Phosphate concentrations had a remarkable enhancement to the absorption of nitrate when phosphate concentration was

A fungus, Aureobasidium pullulans, was isolated from marine biofilm and identified. A bioassay-guided fractionation procedure was developed to isolate and purify antifouling compounds from A. pullulans HN. The procedure was: fermentation broth-aeration and addition of sodium thiosulfate-graduated pH and liquid-liquid extraction-SPE purification-GC-MS analysis. Firstly, the fermentation broth was tested for its toxicity. Then it was treated with aeration and addition of sodium thiosulfate, and its toxicity was almost not changed. Lastly, antifouling compounds were extracted at different pH, the extract had high toxicity at pH 2 but almost no toxicity at pH 10, which suggested the toxicants should be fatty acids. The EC50 of the extract against Skeletonema costatum was 90.9 μg ml(-1), and its LC50 against Balanus amphitrete larvae was 22.2 μg ml(-1). After purified by HLB SPE column, the EC50 of the extract against S. costatum was 49.4 μg ml(-1). The myristic and palmitic acids were found as the main toxicants by GC-MS.

Samples of chromophoric dissolved organic matter (CDOM) in the East China Sea in autumn (October in 2011) were analyzed by excitation emission matrix (EEM) fluorescence spectroscopy combined with parallel factor analysis (PARAFAC). Three terrestrial humic-like components (C1, C2 and C3) and one protein-like component (C4) were identified. Based on spatial distributions, as well as relationships with salinity, the following assignments were made. The three humic-like components (C1, C2 and C3) showed conservative mixing behavior and came mainly from riverine input. The protein-like component (C4) was considered a combination of autochthonous production and terrestrial inputs and a biologically labile component. Path analysis of samples from the middle and bottom layers revealed that the causal effects on C1 were −78.46% for salinity, and −21.54% for apparent oxygen utilization (AOU); those on C2 were −76.43% for salinity, and −23.57% for AOU; those on C3 were −70.49% for salinity, 7.01% for Chl-a, and −22.50% for AOU; those on C4 were −55.54% for salinity, 14.6% for Chl-a, and −29.86% for AOU in middle layer; and those on C4 were −57.37% for salinity, 29.02% for Chl-a, and −13.61% for AOU in bottom layer. Results indicated that CDOM in the East China Sea was mainly affected by terrestrial inputs, and microbial activities also played a key role in biogeochemical processes of CDOM. The application of the EEM-PARAFAC model presented a unique opportunity to observe compositional changes in CDOM in the East China Sea. In addition, the humification index (HIX) suggested that CDOM from the East China Sea was less stable and stayed shorter in the environment.

An in vivo fluorescence discrimination technique for phytoplankton population was developed by using Wavelet packet transform, cluster analysis and non-negative least squares. The technique was used to analyze water samples from different sea regions. For simulative mixtures, when dominant species account for 60%, 70%, 80%, 90% at the division level, the correct discrimination ratios (CDRs) are 83.0%, 99.1%, 99.7% and 99.9% with the relative contents of 58.5%, 68.4%, 77.7% and 86.3%, respectively; when the algae dominance are 60%, 70%, 80%, 90%, 100% at the genus level, the CDRs are 86.1%, 94.9%, 95.2%, 96.8% and 96.7%, respectively. For laboratory mixtures, the CDRs are 88.1% and 78.4% at the division and genus level, respectively. For field samples, the CDRs were 91.7% and 80% at the division and genus level, respectively (mesocosm experiments), and the CDRs were 100% and 66.7% at the division and genus level, respectively (Jiaozhou Bay). The fluorometric technique was used to estimate the phytoplankton community composition and relative abundance of different classes for the April 2010 cruise in the Yellow Sea with the results agreeing with those in published papers by other authors.

The development of techniques for real-time monitoring of the eutrophication status of coastal waters is of great importance for realizing potential cost savings in coastal monitoring programs and providing timely advice for marine health management. In this study, a GS optimized SVM was proposed to model relationships between 6 easily measured parameters (DO, Chl-a, C1, C2, C3 and C4) and the TRIX index for rapidly assessing marine eutrophication states of coastal waters. The good predictive performance of the developed method was indicated by the R2 between the measured and predicted values (0.92 for the training dataset and 0.91 for the validation dataset) at a 95% confidence level. The classification accuracy of the eutrophication status was 86.5% for the training dataset and 85.6% for the validation dataset. The results indicated that it is feasible to develop an SVM technique for timely evaluation of the eutrophication status by easily measured parameters.

In this study, we developed a method to quantify and link the toxic effects in community-level ecosystems with concentrations of petroleum hydrocarbons. The densities of Platymonas helgolandica var. tsingtaoensis, Isochrysis galbana, and Brachionus plicatilis in single-species tests and customized ecosystems were examined in response to a concentration gradient of petroleum hydrocarbons ranging from 0 to 8.0 mg L− 1. A three-population ecological model with interspecies competition-grazing relationships was used to characterize population sizes with concentrations of petroleum hydrocarbons. A threshold concentration of the simplified plankton ecosystem of 0.376 mg L− 1 for petroleum hydrocarbons was calculated from the proposed model, which was higher than the no-effect concentration of 0.056 mg L− 1 derived from the single-species toxicity tests and the predicted no-effect concentration of 0.076 mg L− 1 calculated from the species sensitivity distribution. This finding indicates that interspecies competition and grazing reduced the toxic effect of petroleum hydrocarbons at the community level. The sensitivity analysis for model parameters demonstrates that plankton population biomasses are highly sensitive to filtration rates. Antagonism between interspecies interactions and petroleum hydrocarbon toxicity was attributed to the reduced filtration rate and zooplankton grazing pressure. The proposed method is a simple means to address the concern regarding the impacts of ecological interactions on ecological risk assessments of pollutants.

The 3D fluorescence discrimination of phytoplankton classes was investigated by SA4 multiwavelet, GHM multiwavelet, and coifman-2(coif2) wavelet analysis. Belonging to 35 genera of 7 major phytoplankton divisions in the inshore area of China Sea, Single species cultures of 51 phytoplankton species were employed. The second scale vector (Ca2) of SA4, Ca2 of GHM and the third scale vector (Ca3) of coif2 were selected as feature spectra by Bayesian discriminate analysis (BDA). The reference spectra were obtained via hierarchical cluster analysis (HCA). With average high correct discrimination ratios (CDRs), reference spectra were representative to phytoplankton species. For one-algae samples, the average CDRs were 95.6% at genus level and 86.7% at division level. For the laboratory mixed samples, the average CDRs (one division accounted for 25%, 75% or 100% of the total biomass) were 86.6%, 91.4% and 100% at division level. Moreover, the average CDRs of the dominant species (accounted for 75%) was 79.8% at genus level. Results for the in situ samples were coincided with the microscopic ones at division level with the relative contents of 54.3%–96.5%. The fluorometric discriminating technique was further tested during the cruise in Bohai Sea recently.

In this study we have successfully characterized the fluorescent components of chromophoric dissolved organic matter (CDOM) in the Yellow Sea and the East China Sea in autumn using excitation-emission matrix fluorescence spectroscopy (EEMs) combined with parallel factor analysis (PARAFAC). PARAFAC aids the characterization of fluorescence CDOM by decomposing the fluorescence matrices into individual components. Four humic-like components (C1, C2, C3, and C4), one marine biological production component (C6), and two protein-like components (C5 and C7) were identified by PARAFAC. We researched the distributional patterns of fluorescence intensity, regression analyses between salinity, chlorophyll a concentration and fluorescence intensities of individual fluorophore, and regression analysis between salinity and fluorescence intensities percent of individual fluorophore. The results revealed that C2 and C4 showed conservative mixing behavior, while C1 and C3 possessed conservative mixing behavior in high salinity region and additional behavior in low and middle salinity region, which were considered to be derived from riverine and degradation of organic matter from resuspended and/or sinking particles and show non-conservative mixing behavior. In addition to riverine sources, the tryptophan-like C5 may receive widespread addition (likely from photo-degradation or biodegradation), while the most likely sources for the one marine humic-like C6 and tyrosine-like C7 were biological activity and microbial processing of plankton-derived CDOM, which were suggested to be of autochthonous origin and biologically labile. The application of EEM-PARAFAC modeling presents a unique opportunity to observe compositional changes, different mixing behavior and temporal variability in CDOM in the Yellow Sea and the East China Sea.

The discrete excitation-emission-matrix fluorescence spectra (EEMS) at 12 excitation wavelengths (400, 430, 450, 460, 470, 490, 500, 510, 525, 550, 570, and 590 nm) and emission wavelengths ranging from 600–750 nm were determined for 43 phytoplankton species. A two-rank fluorescence spectra database was established by wavelet analysis and a fluorometric discrimination technique for determining phytoplankton population was developed. For laboratory simulatively mixed samples, the samples mixed from 43 algal species (the algae of one division accounted for 25%, 50%, 75%, 85%, and 100% of the gross biomass, respectively), the average discrimination rates at the level of division were 65.0%, 87.5%, 98.6%, 99.0%, and 99.1%, with average relative contents of 18.9%, 44.5%, 68.9%, 73.4%, and 82.9%, respectively; the samples mixed from 32 red tide algal species (the dominant species accounted for 60%, 70%, 80%, 90%, and 100% of the gross biomass, respectively), the average correct discrimination rates of the dominant species at the level of genus were 63.3%, 74.2%, 78.8%, 83.4%, and 79.4%, respectively. For the 81 laboratory mixed samples with the dominant species accounting for 75% of the gross biomass (chlorophyll), the discrimination rates of the dominant species were 95.1% and 72.8% at the level of division and genus, respectively. For the 12 samples collected from the mesocosm experiment in Maidao Bay of Qingdao in August 2007, the dominant species of the 11 samples were recognized at the division level and the dominant species of four of the five samples in which the dominant species accounted for more than 80% of the gross biomass were discriminated at the genus level; for the 12 samples obtained from Jiaozhou Bay in August 2007, the dominant species of all the 12 samples were recognized at the division level. The technique can be directly applied to fluorescence spectrophotometers and to the developing of an in situ algae fluorescence auto-analyzer for phytoplankton population.

A newly proposed three-dimensional model for the effects of heavy metals on the growth of batch cultures of algae that allows the estimation of the no detected toxic effect concentration (NDEC) is presented. Two batch assays with exposure to copper were investigated in situ. As an endpoint in the in situ studies of ecotoxicology, the carrying capacity, a parameter of the logistic growth model, possesses higher sensitivity and reliability than the routine ecotoxicological endpoints in terms of the analysis based on the theoretical arguments and experimental results. Using the carrying capacity (Bf) as the ecotoxicological endpoint, the NDEC from the proposed model is compared to the NOEC and EC05 on the basis of field derived data. The results indicate that the NDEC is a promising possible alternative parameter to the NOEC.

The feasibility of using a two-rank database of reference spectra based on in vivo fluorescence excitation-emission matrix (EEMs) spectra to assess dominant groups of phytoplankton was explored. Twenty-six species belonging to 20 genera of seven divisions were studied. First, fluorescent characteristics of these EEMs were extracted using Daubechies-7 wavelet analysis. Second, the optimal characteristic spectra of scale vectors (SOCS) and time-series vectors (TOCS) were selected; phytoplankton of different genera were classified using Fisher linear discriminant analysis. Third, SOCS and TOCS reference spectra databases were obtained by hierarchical cluster analysis. Using non-negative least squares as the method to assess the phytoplankton, a two-rank reference spectra database was established according to their respective ability to identify the 2818 single-species samples. Using this fluorimetric technique, the correct identification rates (CIRs) for single-species samples were 88.8–100% at the genus level and 98.8–100% at the division level. Dominant species in the 465 laboratory mixtures had corresponding CIRs of 85.6% and 96.1%. Moreover, 15 of the 19 species used as dominants were correctly identified at the genus level. In 27 natural seawater samples, Prorocentrum donghaiense, Thalassiosira nordenskioldi, and Chaetoceros socialis (bloom-forming species with a density of about 107 cell L−1), and Alexandrium sp. (dominant species with abundance of about 106 cell L−1) were qualitatively identified at the genus level; other dominant species, with densities of 105 to 106 cell L−1, were identified at the division level. The quantitative identification was relatively poor in the natural water samples, and several potential resolutions, including trying both new measuring methods and calculating methods, for future study are given.

The excitation spectra of chlorophyll (Chl) fluorescence can be used to differentiate phytoplankton populations at phylum level in vivo and in situ within a few minutes. The investigated phytoplankton divisions (Dinophyta, Bacillariophyta, Chrysophyta, Cyanophyta, Cryptophyta, Chlorophyta) are each characterized by a specific composition of photosynthetic antenna pigments and, consequently, by a specific excitation spectrum of the Chl fluorescence. Norm excitation spectra (emission of 680 nm and excitation of 400–600 nm) of every division were obtained from several species per division by a F4500 fluorescence spectrophotometer. Fisher’s linear discriminant analysis of the norm spectra shows that the divisions could be discriminated. The discrimination method, established by multivariate linear regression and weighted least squares, was used to differentiate the phytoplankton samples cultured in the laboratory and samples collected from the Jiaozhao Bay at division level. The correctly discriminated samples were more than 94% for single algal species ones, more than 84% for simulatively mixed ones, more than 83% for real mixed ones and 100% for samples collected from the Jiaozhou Bay for the dominant species. The method for phytoplankton differentiation described here can be applied to routine checking by fluorescence spectrophotometer, and benefit the monitoring and supervision tasks related to phytoplankton populations in the marine environments.

The feasibility of utilizing discrete excitation-emission spectra (DEEMs) to identify dominant groups of phytoplankton at both the genus and division levels was investigated. First, the characteristics of in vivo DEEMs were extracted using Coif2 wavelet. Second, optimal characteristic spectra of scale vectors (SOCS) and time-series vectors (TOCS) were selected by Fisher linear discriminant analysis (FLDA). Third, the SOCS and TOCS were sorted using hierarchical cluster analysis (HCA), and a two-rank database was established according to their discrimination ability. Fourth, the discrimination of phytoplankton was established by nonnegative least squares (NNLS). For single-species samples, the correct identification ratios (CIRs) were 62.9%–100% at the genus level and 95.1%–100% at the division level. The dominant species in the mixtures had corresponding CIRs of 87.5% and 97.9%, and 23 dominant species were correctly identified. Prorocentrum donghaiense D. Lu, Thalassiosira nordenskioeldi Cleve, Chaetoceros socialis Lauder (bloom-forming species with a density of about 107 cell·L−1), and Skeletonema costatum (Grev.) Cleve (a dominant species with a density of 104–106 cell·L−1 in seawater) were identified at the genus level. Other dominant species in seawater were identified at the division level if their density was 105–106 cell·L−1.

In vivo fluorescence methods are efficient tools for studying the distribution of phytoplankton in nature. Different algae species usually have different pigments with different ratios, which results in different fluorescence emission spectra. Based on multiple excitation wavelength fluorescence emission spectra, a discrimination technique is established in this study. The discrimination method, established by multivariate linear regression and weighted least-squares, was used to differentiate the samples cultured in the laboratory and collected from Jiaozhou Bay near Qingdao at the division level. The correctly discriminated samples were ≥ 86% for single algae samples, ≥ 88% for simulatively mixed ones, ≥ 91% for physically mixed ones and 100% for samples collected from Jiaozhou Bay. The result in this research is more definite for the physically mixed samples in the laboratory. The method described here can be employed to monitor the phytoplankton population in the marine environment.

An in vivo 3D fluorescence discrimination technique for ten harmful algal bloom (HAB) species that belong to eight genera of four divisions was developed by wavelet analysis. Daubechies-7 (db7) was employed as the mother wavelet. The fifth scale domains were selected as the discriminant characteristic spectra (DCS). Based on the DCS, The phytoplankton species at different growth stages were classified correctly at both the division and the genus level by Bayesian discriminant analysis (BDA). Based on the reference spectra of the DCS, the discrimination method of the phytoplankton species was established by the nonnegative least squares (NNLS) method. The correct discrimination ratios (CDRs) for samples of the single species were 96.1% with 0% blank noise and 93.3% with 10% noise at the genus level, while the CDRs were both 100% with 0% or 10% blank noise at the division level. When blank noise was up to 20%, the CDRs were down to 85.2% at the genus level and 98.0% at the division level. For the mixture samples, the CDRs of the dominant species were 98.3% and 96.3%, respectively, at the division level and at the genus level. As dominant species, Prorocentrum minimum (Pm), Gymnodinium simplex (Gs), Scrippsiella trochoidea (Sc), Skeletonema costatuma (Sk), Chaetoceros (Cu and De), Phaeocystis globosa (Cg) and Chlorella pynnoidosa (Ch) can be correctly discriminated at both the division level and the genus level.

A glass electrophoresis microchip integrated a flow-type chemluminescence (CL) detection cell has been developed and evaluated. The chip pattern is a double-T-type electrophoretic sample injection and separation combining with a Y-type chemiluminecent detector. The double-T geometry allows for high-efficiency sample injection and geometric definition of sample plug size. The branch of Y was used as CL reagent channel, and the CL reagent was delivered by a tab-made micropump. Bis[(2,4,6-trichlorophenyl)]oxalate-H2O2 CL system was employed to detect dansyl amino acids. On this microchip, dansyl-phenylalanine and -sarcosine were successfully separated by electrophoresis and detected within 250 s. The detection limits (S/N = 3) of dansyl-phenylalanine and -sarcosine could reach to 2.8 and 3.2 muM, respectively, due to the vigorous dilution of sample with CL reagent and timely removal of the waste solution from reaction area. (C) 2004 Elsevier B.V. All rights reserved.