[Selective Inhibition of Rice Straw Extract on Growth of Cyanobacteria and Chlorophyta].

Rice straw is supposed to be an environment-friendly biomaterial for inhibiting the growth of harmful blooms of the cyanobacterium Microcystis aeruginosa. The effects of rice straw extract(RSE) on algal growth, morphologic parameters(cell size), and physiological parameters(in vivo Chl-a fluorescence) were investigated using flow cytometry. We examined the selective inhibitory potential of rice straw on four cyanobacterial strains(toxic and non-toxic Microcystis aeruginosa, toxic Anabaena flos-aquae, and Microcystis ichthyoblabe), in comparison with inhibitory effects on three common freshwater green algae(Selenastrum capricornutum, Chlorella pyrenoidosa, and Scenedesmus obliqnus). Concentrations from 2.0 to 10.0 g·L-1 of RSE were found to efficiently inhibit the growth of cyanobacteria in a dose-dependent manner, simultaneously modifying the in vivo Chl-a fluorescence and cell size. The 50% growth-inhibition concentration(7 d) of A. flos-aquae, M. ichthyoblabe, M. aeruginosa(toxic strain), M. aeruginosa(non-toxic strain) was 1.72, 2.21, 2.92 and 5.72 g·L-1, respectively. Interestingly, the growth and cell size of C. pyrenoidosa and S. obliqnus increased with the addition of RSE and colony formation was observed. In the case of S. capricornutum, the inhibitory effect of RSE on growth and in vivo Chl-a fluorescence occurred at 1.0-4.0 g·L-1, while RSE induced a stimulatory effect on algal growth at 8.0-10.0 g·L-1. Taken together, the sensitivity of cyanobacteria to RSE was significantly higher than that of S. capricornutum, C. pyrenoidosa and S. obliqnus. The higher sensitivity of PSⅡ reaction center of cyanobacteria and the ability to form colonies of green algae may have important implications for the species-specific allelopathic antialgal activity of rice straw.

Optimum dredging time for inhibition and prevention of algae-induced black blooms in Lake Taihu, China.

Dredging, which is the removal of polluted surface sediments from a water body, is an effective means of preventing the formation of algae-induced black blooms. However, an inappropriate dredging time may contribute to rather than inhibit the formation of black blooms. To determine the optimum dredging time, four treatments were simulated with sediment samples collected from Lake Taihu: dredging in January 2014 (DW), April 2014 (DA), July 2014 (DS), and no dredging (UD). Results showed that typical characteristics associated with black blooms, such as high levels of nutrients (NH4 (+)-N and PO4 (3-)-P), Fe(2+), ∑S(2-) ([HS(-)] + [S(2-)]), and volatile organic sulfur compounds (VOSCs), including dimethyl sulfide (DMS), dimethyl disulfide (DMDS), and dimethyl trisulfide (DMTS), were more effectively suppressed in the water column by DW treatment than by UD treatment and the other two dredging treatments. The highest concentrations of NH4 (+)-N and PO4 (3-)-P in the UD water column were 4.09 and 4.03 times, respectively, those in the DW water column. DMS levels in the UD and DS water columns were significantly higher (p < 0.05) than those in the DW water column, but DMDS and DMTS levels were not significantly different between the treatments. After several months of dredging, surface sediments of the DW and DA treatments were well oxidized, and concentrations of Fe(2+) and ∑S(2-) were lower than those in UD and DS treatments because of material circulation between sediments and the water column. Water content, which is important for the transport of matter to the overlying water, was lower in the dredged sediments than in the undredged sediments. These factors can suppress the release of Fe(2+) and ∑S(2-) into the water column, thereby inhibiting the formation of black blooms. Black coloration occurred in the UD water column on the seventh day, 2 days later, and earlier, respectively, than the DW and DS water columns and almost on the same day as in the DA water column. This phenomenon is mainly attributed to the oxidation of the new sediment surface in the DW and DA water columns, suppressing the release of sulfur into the water column, because of a long incubation period. Thus, dredging in the winter can prevent the formation of black blooms, while dredging in summer may contribute to them.

[Sources of dissolved organic carbon and the bioavailability of dissolved carbohydrates in the tributaries of Lake Taihu].

Surface water samples of Yincungang and Chendonggang Rivers were collected from September 2012 to August 2013 in Lake Taihu. Water temperature, Chlorophyll a and bacterial abundance were analyzed, as well as dissolved organic carbon (DOC) concentrations, stable carbon isotope of DOC (Δ13C(DOC)), specific UV absorbance (SUVA254 ) and dissolved carbohydrates concentrations. Δ13C(DOC) ranged from -27.03% per thousand ± 0.30% per thousand to -23.38%per thousand ± 0.20% per thousand, indicating a terrestrial source. Both the autochthonous and allochthonous sources contributed to the carbohydrates pool in the tributaries. Significant differences in PCHO (polysaccharides) and MCHO (monosaccharides) concentrations were observed between spring-summer and autumn-winter (P < 0.01, n = 12; P < 0.01, n = 12), which might be caused by the variation in the sources and bioavailability of carbohydrates. PCHO contributed a major fraction to TCHO (total dissolved carbohydrates) in autumn and winter, which could be explained by the accumulation of undegradable PCHO limited by the low water temperature; MCHO contributed a major fraction to TCHO in spring and summer, which might be caused by the transformation from PCHO by microbes at high water temperature.

[Genetic diversity of picoeukaryotic phytoplankton in the lakes along the middle-lower reaches of the Yangtze River].

The genetic diversity of picoeukaryotic phytoplankton in the 30 lakes along the middle-lower reaches of the Yangtze River was studied using flow cytometry combined with terminal restriction fragment length polymorphism (T-RFLP). The objectives of this study were to confirm the variance in the genetic diversity of picoeukaryotic phytoplankton among the lakes and to reveal its main affecting factors. Though the lakes investigated tended to or already were eutrophic, T-RFLP profiles of 18S rRNA gene fragments from picoeukaryotic phytoplankton showed high diversity. There were altogether 197 T-RFs detected from the lakes that we investigated, with 89 of them obtained in less than 3 lakes. Cluster analysis indicated their similarity was lower than 80%. Shannon-wiener diversity index showed that mesotrophic lakes contained more diverse picoeukaryotic phytoplankton community than eutrophic lakes. The canonical correspondence analysis revealed that the concentration of the total nitrogen had the most important impact on the picoeukaryotic phytoplankton communities (P =0. 006). The results showed that the genetic diversity of picoeukaryotic phytoplankton in the lakes were of great environmental heterogeneity and closely related to the trophic status. Two CCA axes can only explain 10.0% of the total variance in picoeukaryotic phytoplankton composition, suggesting that the evolution of picoeukaryotic phytoplankton was probably connected to the top-down manipulation as well.

[Effects of simulated elevation of atmospheric CO2 concentration on the physiological features of spring phytoplankton in Taihu Lake].

To disclose the impact of different CO2 concentrations (270 x 10(-6), 380 x 10(-6), 750 x 10(-6)) on physiological features of spring phytoplankton, an in situ simulated experiment was carried out in Meiliang Bay of Taihu Lake from 29 April to 26 May in 2012. The results showed that atmospheric CO2 elevation would significantly alter the pH value and carbonate chemical environments of Taihu Lake, resulting in weakening the advantages of carbon concentrating mechanism (CCM) of phytoplankton. Phytoplankton in Taihu Lake tended to use more dissolved CO2 (CO2, aq) due to the deliberate CO2 sequestration under the high CO2 level treatment. When atmospheric CO2 concentration doubles at the end of century, the maximum growth rate constant of phytoplankton (U(max)), NPP, chlorophyll a (Chl-a)-specific NPP would increase by 63.1%, 69.6% and 33.8%, respectively. Atmospheric CO2 elevation promoted the maximum photosynthetic efficiency of chlorophyta and bacillariophyta in Taihu Lake and its promotion effect on bacillariophyta was more notable than that on chlorophyta. However, it did not change the photosynthetic efficiency of cyanobacteria which was very low in spring. Meanwhile, the stoichiometry value of phytoplankton changed significantly due to the CO2 elevation, as phytoplankton cells assimilated more C and N, but less P under the treatment of high CO2 level. Our results indicated the enhanced CO2 level could dramatically change the physiological features of phytoplankton. This information would help us to understand and predict the response of phytoplankton in Taihu Lake to the future climate change.

[Use of flow cytometric sorting to assess the diversity of eukaryotic picophytoplankton of lakes].

A novel approach based on flow cytometric sorting followed by construction of 18S rRNA clone libraries was used to study the diversity of eukaryotic picophytoplankton of lakes. The composition of eukaryotic picophytoplankton community appeared highly variable in three lakes. Eukaryotic picophytoplankton was dominated by Cryptophyta in the Lake Xuanwu, and was mainly composed of Cryptophyta and Chrysophyta in the Lake Zixia. In the Lake Taihu, four phyla were discovered, including Cryptophyta, Chrysophyta, Bacillariophyta and Chlorophyta. Meanwhile, the diversity of eukaryotic picophytoplankton differed in various lake regions. In the Meiliang Bay, Chrysophyta was the dominant, and the other three phyla were found in the Gonghu Bay. In the central lake, all of those four phyla were discovered, implying this region contained the highest diversity. The canonical correspondence analysis between the diversity of eukaryotic picophytoplankton and environmental factors revealed the concentration of total phosphorus had the highest important impact on the eukaryotic picophytoplankton communities.

[Effects of the rice straw on Microcystis aeraginosa analyzed by different physiological parameters].

The growth and physiology of bloom-forming cyanobacterium Microcystis aeruginosa were determined by the flow cytometry when exposed to rice straw extract for 15 d. The cell growth, cell integrity, mitochondrial transmembrane potential, and esterase activity were used to evaluate the physiological response in Microcystis aeruginosa. Rice straw extract stored for 5 days significantly inhibited the growth of Microcystis aeruginosa in a concentration-dependent way; Most of the algae cells (> 98%) remained complete membranes in all the concentration treatments; Compared with the control cultures, the rice straw induced both negative and positive effects on the esterase activity for each test within 4 days, while the inhibition exceeded the stimulation effect. After a 7 d exposure, only the inhibition effect was found. Neither the inhibited nor stimulated effects was observed after algae exposure from 10 d to 15 d. Evident changes was found in the membrane potential during 7 d experiment, whereas inhibition effect became weaker after 10 d and 15 d exposure, in consistent with the result of esterase activity. These results confirmed that the rice straw extract might provide both dominant inhibition and relatively weak stimulation effects. After a long time exposure, inhibition effect became limited while stimulation effect disappeared. The action of rice straw may be algistatic (preventing algal growth) but not algicidal (killing algae).

[Analysis of meteorological factors of forming feculent and anaerobic water aggregation induced by algal bloom in Taihu Lake].

The water quality pollution problem about feculent and anaerobic water aggregation (FAWA) induced by algal bloom in Taihu Lake, which is often called 'hufan' in Chinese, was studied. Its forming process is divided into 3 phases, i. e., material elements forming of FAWA, anaerobic products to be brought to the water surface and the maintaining of FAWA in the water surface. The conventional observational data from Wuxi meteorological station was analyzed. The result shows that there are similar meteorological characteristics of two FAWA phenomena in Taihu Lake in May, 2007 and May, 2008. A numerical simulation was performed to prove the analysis results. It indicates that propitious meteorological condition is one of the necessary forming factors of FAWA, which provides thermal and dynamical environment for FAWA. During the first phase, the weather conditions, such as high air temperature, gentle breeze and nearly invariable wind direction, maintain for more than 3 days and cause algal bloom to aggregate, then die, sink and anaerobic decay near lake bank. All these provide the precondition for FAWA. During the second phase, when the cold air mass passes across the Taihu basin, almost counter-direction wind, which maintains for more than 1 day with higher speed and lower air temperature, makes anaerobic products to be brought to the water surface by uplifted current. This is the trigger mechanism of FAWA. During the last phase, continual high air temperature and gentle breeze is favorable for FAWA in the water surface. Because meteorological factors are predictable, this research provides a way and basis for the further study of warning and controlling approaches of FAWA.

[Correlation analysis among characters of gas vesicle in Microcystis strains].

In order to explore the roles of gvpA copies and repeated sequences of gvpC, three Microcystis strains including M. aeruginosa FACHB910, M. aeruginosa FACHB930 and M. wesenbergii FACHB929 were used in this research. The length and diameter of gas vesicle, relative gas vesicle volume, appear pressure values, critical pressure values, cell turgor values were measured, and the correlations among these characters, gvpA copies, and repeated sequences of gvpC were analyzed. The results indicate that there are a significant positive linear correlation between gvpA copies and relative gas vesicle volume (r = 0.999); gvpA copies are negatively correlated with diameter of gas vesicle (r = -0.861). However, repeated sequences of gvpC have a significant positive correlation with diameter of gas vesicle (r = 0.911), and have significant negative correlations with relative gas vesicle volume, appear pressure values and critical pressure values, with the correlation coefficient of -0.851, - 0.999, - 0.928 respectively. So we presume that gvpA copies are probably the primary impact factor for relative gas vesicle volume. The diameter of gas vesicle is not only regulated by repeated sequences of gvpC, but also regulated by gvpA copies.

Assessing the combination effects of environmental estrogens in fish.

The method on combined effects of environmental estrogens and mixture environmental risk assessment was discussed. Batch tests were conducted to assess the in vivo potency of mixtures of estrogens using plasma vitellogenin concentrations in male crucian carp (Carassius carassius) as the endpoint. A nonlinear regression was determined on the concentration response relationship for the single chemical of 17ß-estradiol (E(2)), 17α-ethynylestradiol (EE(2)), 4-tert-octylphenol (OP), bisphenol A (BPA), and that of the mixed compounds at equipotent concentrations (E(2)-EE(2), E(2)-EE(2)-OP-BPA), the mixture was tested using a fixed-ratio design. On the basis of statistical selection criteria, the best-fit model is chosen individually for each set of data. Furthermore, the bootstrap methodology is applied for constructing confidence intervals for the estimated effect concentrations. The combined effects of the mixture can be predicted using biomathematical models based on the concentration and potency of the individual mixture components. The finding of non-monotonic dose-response relationship and the combined effects can be accurately predicted in whole range of exposure concentration by the reference models, whereas the outcome of simple effect summation with a great deal of indetermination. Results suggested that there can be a risk of mixture effects. The potential impact of components on mixture would depend predominantly on its concentration, the mixture ratio, and its relative potency. Existing environmental risk assessment procedures are limited in their ability to evaluate the combined effects of chemical mixtures, therefore further improvement is needed.

[Quantitative retrieval of chlorophyll a concentration in Taihu Lake using machine learning methods].

We evaluated the performance of two machine learning methods, artificial neural net (ANN) and support vector machine (SVM), for estimation of chlorophyll a in Taihu Lake from remote sensing data. The theoretical analysis has been done from basic theory and learning target of these two methods first. Then two empirical algorithms have been developed to relate reflectance of MODIS to in situ concentrations of chlorophyll a. The performance of ANN and SVM is comparatively analyzed in terms of validation, stability and robustness assessment and chlorophyll a distribution of Taihu Lake from two algorithms. The root of mean square deviation (RMSE) and average relative error (ARE) of validation data is only 5.85 and 26.5% of SVM retrieval model, however, RMSE and ARE of ANN model is 13.04 and 46.8%. Stability and robustness assessment suggest that SVM provides the better performance than ANN. And the retrieval results show that the chlorophyll a distribution of the whole lake from two algorithms is similar, however, the chlorophyll a concentration in the eastern region and central region of Taihu Lake is distorted by ANN model because of the limitations, such as learning target setting and over-learning in net construction.

Vitellogenin induction by a mixture of steroidal estrogens in freshwater fishes and relevant risk assessment.

The study method on combined effects of environmental contaminant mixture and ecological risk assessment was discussed. Batch tests were conducted to assess the in vivo potency of binary mixtures of estrogens using plasma vitellogenin concentrations in male crucian carp as the endpoint. The estrogenic potencies of 17beta-estradiol (E(2)) and 17alpha-ethynylestradiol (EE(2)) were determined following 14 day exposure to the individual chemicals and equipotent binary mixtures. A Nonlinear regression was obtained and 95% confidence limits of effect concentration were achieved using the bootstrap method. Concentration-response curve for fixed ratio binary mixtures of E(2) and EE(2) was compared with those for individual chemicals, using the biomathematical models of concentration addition (CA) and independent action (IA). A complete overlap was found for the CA predictions with the 95% confidence interval of the best-fit regression line of the observed responses, and the IA predictions was shown lower than the observations. The observed mixture effects were considerably higher than those of the hormone alone and far exceeded the 95% confidence interval of the estrogen regression lines. The predicted effects of binary mixtures at different mixture ratios indicated that the potential impact of components on mixture would depend predominantly on its concentration, the mixture ratio and its relative potency. Results suggested that E(2) and EE(2) acted together in an additive manner and the combined effects can be accurately predicted in whole range of exposure concentration by the models of CA and IA, the model of CA might be realistic, but more useful for ecological risk assessment.

[Ammonia-oxidizing bacteria community composition at the root zones of aquatic plants after ecological restoration].

To investigate the effects of aquatic plants on ammonia-oxidizing bacteria (AOB) at their root zones, four species of aquatic plants were selected, Phragmites communis, Typha angustifolia L., Potamogeton crispus L., and Limnanthemun nymphoides, which were widely used in ecological restorations. AOB in the samples were enumerated by most-probable-number (MPN) method. Nested polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) procedures were performed with ammonia oxidizer-selective primers. Main DGGE bands were excised from the gel and sequenced for phylogenetic affiliation. Results indicate that AOB densities are always higher at the root zones of emergent plants (Phragmites communis 2.8 x 10(5) cells/g and Typha angustifolia L.4.3 x 10(5) cells/g) than those of submerged and floating-leaved plant (Potamogeton crispus L. 9.3 x 10(4) cells/g and Limnanthemun nymphoides 7.7 x 10(4) cells/g). At the root zones, the oxidation-reduction potential is above zero and NH4+ concentration is lower than it in the bare surface sediment. Fourteen major bands were recovered from the DGGE gel, re-amplified and sequenced. Although the identified bands have their respective similar sequences in GenBank, most of them are related to Nitrosomonas-like. This type of bacteria would play an important role of nitrogen cycle in lake sediment after ecological restoration.

[Mixture effects to vitellogenin induction by four environmental estrogens in freshwater fish].

Combined effects of estrogenic compounds to high risk life-form were demonstrated, and the study method on combined effects of environmental contaminant mixture and environmental risk assessment were also discussed. A nonlinear aggression was determined on the changes of plasma vitellogenin concentration in crucian carp via the environmental pollutant exposure concentration, and the concentration-response relationship was determined for the single chemical of estradiol, ethynylestradiol, bisphenol A, and octylphenol, and that of the mixed compounds at equipotent concentrations. The combined effects of the four xenoestrogens were tested using indices of mixture toxicity and the biomathematical models of concentration addition or independent action. Weibull function was indicated as the best-fit function (R2 > or = 0.92) with curve estimation, the 95% confidence limits of effect concentration was achieved using the bootstrap method, the media effective concentration (EC50) with 95% confidence interval was 0.007 9 (0.006 8-0.010 0), 0.098 7 (0.090 0-0.111 0), 63.50 (56.58-70.62) and 250.59 (228.46-271.99) Mg x L(-1) respectively. Results suggested that estrogenic chemicals acted together in an additive manner and the combined effects can be accurately predicted in whole range of exposure concentration by the concept of similar joint action or concentration addition.It is proved as a scientific and feasible method to apply the model of joint action whereas the outcome of indices with a great deal of indetermination.

[Genetic diversity of eukarytic microplankton in different areas of Lake Taihu].

The methods of DGGE and cloning/sequencing were used to study the diversity and community structures of small planktons (0.8 - 20 microm) in different areas of Lake Taihu. DGGE indicated that there were markly various fingerprints in different areas and the diversities were higher in areas with low trophic status than those with relatively high trophic status. There were 23, 24 DGGE bands in East Taihu and Gonghu Bay, respectively (Shannon index were 3.135 and 3.178) and 18 bands in both Meiliang Bay and Wuli Bay (Both shannon index were 2.890). The result of cloning/sequencing indicated that there was a high diversity of small planktons in Lake Taihu and most of them phototrophic flagellate, heterotrophic flagellate, ciliate and fungi. There were various community structures in the three different clone libraries. In Meilang Bay, 28.6% OTUs(operational taxonomic unit)belonged to heterotrophic flagellate, followed by Cryptophyta (22.9%) and Chrysophyta (14.3%). In Central Lake, 25.7% OTUs belonged to Chrysophyta, followed by heterotrophic flagellate (20.0%) and Cryptophyta (14.3 %). In East Taihu, ciliates were the dominant group and only a few heterotrophic flagellates (40.9%) were detected. In addition, fungi were relatively abundant (12.2%) in this area.

[Comparison of overwintering and rrecruitment of cyanobacteria in Taihu Lake and Chaohn Lake].

Dynamics of overwintering and recruitment of cyanobacteria were studied in Taihu Lake and Chaohu Lake. The results demonstrated that cyanobacteria sank to the sediment in autumn (November) and recruited to water column in May in Taihu Lake. From November to next May, the cyanobacteria kept growing with an increased growth rate from March to May in the sediment. A similar pattern of overwintering and recruitment of cyanobacteria was found in Chaohu Lake, which showed the cyanobacteria sinking in November and recruitment in spring with the cyanobacteria growing in the sediment, while the cyanobacteria recruited to water column from March to April. Our results showed there was typical overwintering and recruitment of cyanobacteria in Taihu Lake and Chaohu Lake. The numbers of cyanobacteria in sediment represented by the almost same pigments content in different lake areas of Taihu Lake according to nutrient levels probably implied the little relationships of the numbers in sediments with the summer bloomed biomass of cyanobacteria.

[Effects of anthropogenic organic matter inputs on stable carbon and nitrogen isotopes in organisms from microbial food chain in Taihu Lake].

Stable isotope analyses of carbon and nitrogen were used to evaluate autochthonous versus allochthonous contribution to the main microbial food loop components in the four sampling sites based on different trophic status in Taihu Lake. On average, the delta13 C and delta15 N values of organic matter (OM) sources (bacteria, cladocera, particulate and sedimentary organic matter) and the delta13 C of dissolved inorganic carbon (DIC), which are the main components in microbial food chain, showed the lowest values at estuary location compared with the other three sites, reflecting a strong influence by terrestrially derived nutrients and organic matter. The mean delta13 C value of dissolved organic matter (DOM) that we measured was close to the estimated terrestrial delta13 C - 26 per thousandd, suggesting an allochthonous-derived organic C pool. Particulate organic matter (POM) was supposed to be mainly dominated by algae under the assumption of a constant fractionation from DIC to phytoplankton of 22 per thousand. Cladocera had a lower delta13 C than the average delta13 C of POM (0.2 per thousand) and bacteria (2.5 per thousand), supposing a lipid accumulation or selective feeding a more delta13 C-depleted algal fraction (pico- and nano-plankton, < 50 microm) of POM. The contribution of autochthonous versus allochthonous carbon to the bacterial biomass was estimated by applying a two-member mixing model using a delta13 C of - 26 per thousand as the allochthonous end member. The bacterial biomass consisted of 61.2% allochthonous carbon at estuary point with large terrestrial effluents, while in the large open lake area, bacteria was mainly supported by autochthonous OM (58.5% - 92.9%). The results substantiate the finding that the analysis of carbon and nitrogen stable isotopes can help to elucidate sources and sinks of organic matter in Taihu Lake, which are characterized by a great spatial variability and complexity.

[Relationship of heterogeneous sensitivity to metal ion and its cell cycle in Scenedesmus obliquus].

It is important to investigate the effect of contamination on the heterogeneous cells characteristically observed within single algae species, which can be helpful to understand the sensitivity of organism and the toxicity mechanism. Flow cytometry was used to assess sensitivity to metal ion (Cd2+ and Ni2+) in Scenedesmus obliquus. By determination of esterase activity in cell fractions gated by FSC (an indicator of the cell volume), it was shown that the resistance to metal ion was improved as the cell volume increased. By simultaneously examining FSC and DNA content, a relationship between the cell volume and the cell cycle stage was observed: as the cell volume increased, the S. obliquus cells changed from G1 phase to G2/M phase. The cells in G2/M phase had more resistance to metal ion. Thus, this observation indicate that the difference of cell cycle may be the important cause of heterogeneous sensitivity to metal ion in S. obliquus.

[Water quality risk assessment for sediment dredging operations, Wulihu in Taihu Lake].

To assess impacts and risks of sediments dredging on water environmental quality of Wulihu Lake, the principal components analysis method and the Monte Carlo romantic sampling model were used. Five principal constituents of Wulihu Lake were generalized and defined by using sixteen water quality index data, and it was studied the characteristics of the variation of every principal component and the comprehensive component with sediment dredging. The result show that during sediment dredging the water quality of Wulihu Lake were more serious, and the values of the comprehensive component and the principal component F1 increased to the highest level, were 1.15 and 5.0, respectively. This indicated that sediment dredging had great impacts on the water environment of Wulihu Lake, including sediment re-suspension, water transparency decrease, release of the internal nutrients and heavy metal ions etc. The risk of heavy metal release from re-suspended sediments and its certainty level were assessed and forecasted with the equilibrium partitioning model and the Monte Carlo romantic sampling method. The results also suggested that during sediment dredging, most of heavy metal ions have a great risk of release from re-suspended sediments with the certainty level over 90%; especially for Ni2+ and As, the release levels of which were 28.6% to approximately +infinity of EQS and 34% to approximately +infinity of EQS, respectively. Thus, sediment dredging would cause a temporary risk of water quality deterioration in Wulihu Lake. Others, the application of Monte Carlo sampling model may offer a new tool to assess a potential risk of deteriorations in water environment with sedimentsdredging.

[The application of the gene-recombinated cell in the detection of PCBs compounds in environmental samples].

To develop novel and rapid bioassay systems for detection of PCBs in environmental and biological samples, two lines of gene-recombinated cells containing reporter gene, green fluorescent protein (GFP) and luciferase (Luc), were be chosen to detect the PCBs in the water, sediment and biological samples from environment. The result showed that the correlation between RFU of GFP and Luc activity and PCBs standard sample concentration was fine, r was 0.99188 and 0.98239 respectively. Compared with the instrument analysis with GC-ECD, the correlation between RFU of GFP and Luc activity and PCBs concentration in environmental and biological extracts was also fine. The method offered a new way of screening and semi-quantitative bioassay for PCBs compounds in environmental and biological samples.