[Driving Factors Analyze of Phytoplankton Community by Comparison of Population and Functional Groups and Water Quality Evaluation in Dongting Lake].

Phytoplankton is the most important component of water ecosystems, which could indicate the state of the water environment owing to its sensitivity to water environment variation. However, its response to the environment is influenced by classification methods. To understand the phytoplankton population(phyla and genera) and functional groups(FG) for driving response characteristics and applicability to the environment in Dongting Lake, a total of four samples were collected from the lake from March to December 2019, and the distribution characteristics of the phytoplankton population and functional groups and their responses to environmental factors were compared and analyzed. Meanwhile, the applicability of the TLI index, Shannon-Wiener index, and Q index was compared in Dongting Lake. The results showed that a total of 61 genera belonging to six phyla of phytoplankton were detected in Dongting Lake, which could be divided into 23 functional groups and nine dominant functional groups. The succession trend of functional groups was P/MP/D(March)→MP/P/J(June)→MP/H1(September)→Y/P/MP(December). The results of hierarchical segmentation showed that the population distribution and change in phytoplankton were driven by environmental factors more than the area in Dongting Lake. The main environmental factors affecting phytoplankton population and functional groups were water temperature(WT), permanganate index, dissolved oxygen(DO), conductivity(Cond), water level(WL), and total phosphorus(TP). RDA analysis showed that phytoplankton functional groups identified phytoplankton response to environmental factors better than phytoplankton population. It was shown that using the Q index to evaluate water quality had better applicability in Dongting Lake.

Coagulation-flocculation: a potential application for mosquito Larval Source Management (LSM).

Larval mosquitoes have a more limited home range and lower resistance to adverse environment than adults, thus can be ideal targets for vector control in some cases. Coagulation-flocculation technology, which could be used for water treatment in breeding sites of several vector mosquito species, can significantly change both the distribution of organic particles and surface sediment characteristics in water environment. The aim of this study was to explore the effect, principle and possibility of using coagulation-flocculation technology in immature mosquitoes killing. In this study, dechlorinated water was treated with Poly Aluminum Chloride (PACl, sewage treatment using), and we observed the impacts of PACl treatment on the development and survival of immature Culex pipiens pallens mosquitoes. When exposed to PACl treatment, physical effect is believed to be a main reason of coagulation-flocculation caused high larvae mortality: Ⅰ) alum floc layer increases the difficulty of larvae foraging, leads larvae starving to death; (Ⅱ) the little floc particles could attach to the lateral hair of larvae, which impede floatation process and then surface respiration by larval mosquitoes. The alum floc layer had a good killing effect on the mosquito larvae, presented the half lethal time (LT50) of 2d, the 90% lethal time (LT90) of 8.7±7.3 ∼ 14±4.5 d, and the pupation rate of 0 ∼ (6.5±0.5)%, respectively. Our results indicates alum floc, produced by PACl coagulation-flocculation, was shown to be highly active against 1st∼2nd instar larvae, the high mortality rate of immature mosquitoes as a result of physical effect. The observations suggest that coagulation-flocculation technology offers a novel potential approach to a sustainable and low-impact mosquito control method.

[Research on Remediation of Heavy Metals in Sediment with Lotus and Water Lily].

The aquatic landscape plants lotus and water lily were selected to repair the heavy metal in black odorous river sediments. With ICP-AES inductively coupled full spectrum of direct reading plasma emission spectrometry, the total and forms of content of heavy metals Cd, Cr, Cu, Ni, Pb in sediment and plants, the distribution of heavy metals in plants to were determined .The results showed that the average removal rate of the lotus in terms of the removal of heavy metals in the sediments was 20.42% while that of water lily was 18.23%; after lotus and water lilies were planted, the forms of content of heavy metals in sediments were decreased, the phytoremediation of main forms of Cr, Pb, Ni in sediments were theresidual state; the main forms of Cd, Cu were extractable. The distribution of Cu, Ni among the water lilies was stem

[Optical signatures of chromophoric dissolved organic matter in water body of Tien Lake].

The water samples of the Tien Lake were collected for the three-dimensional fluorescence spectrum detected. And parallel factor analysis (PARAFAC) and principal component analysis (PCA) were used for the spectra analyzing to know the main factor and relative contribution of the chromophoric dissolved organic matter (CDOM). PARAFAC decomposed CDOM into four components, the humic-like: C1 (240, 415), C3 (265, 525), C4 (255, 505) and the protein-like: C2(230/280, 330). The fluorescence intensity of CDOM components was high in north and estuary of the lake, but low in the other region. All the four components show significant positive correlations (p < 0.01), this result means they may have the same sources. Principal component analysis shows that these four components of the Tien Lake are all from terrestrial organic matter, meanwhile its DTN, DTP, DON may also come with the terrestrial substance. These components of Tien Lake can well be connected with dissolved nutrient salts by nonlinear multiple regression, which means we can use the three-dimensional fluorescence spectrum results of CDOM to indicate the eutrophication degree of Tien Lake.

Molecular phylogenetic analysis of dominant microbial populations in aged refuse.

The phylogenetic analysis of dominant microbial populations in 8-year-old refuse samples was done in terms of the whole Bacterial and Archaeal domains. The results indicated that the Bacterial 16S rRNA genes sequences from the aged refuse were largely affiliated with the genus Bacillus, and that more than 60 % of the Archaeal sequences were closely related to the methanogenic archaeon. Some inferentially identified extremophilic organisms, particularly alkaliphiles and/or halophiles, were noted to be present in the aged refuse. Moreover, molecular evidence for the occurrence of ammonia-oxidizing Archaea in aged refuse was reported, which opens up avenues for elucidating its role in ammonia transformation in landfill systems. It seems reasonable to assume that the highly complex environment within the landfill systems may select for microbial populations with versatile metabolism and strong adaptation. These findings underline the need for further biochemical and ecological study of these organisms in aged refuse.

Seasonal variations and aeration effects on water quality improvements and physiological responses of Nymphaea tetragona Georgi.

Seasonal variations and aeration effects on water quality improvements and the physiological responses of Nymphaea tetragona Georgi were investigated with mesocosm experiments. Plants were hydroponically cultivated in six purifying tanks (aerated, non-aerated) and the characteristics of the plants were measured. Water quality improvements in purifying tanks were evaluated by comparing to the control tanks. The results showed that continuous aeration affected the plant morphology and physiology. The lengths of the roots, petioles and leaf limbs in aeration conditions were shorter than in non-aeration conditions. Chlorophyll and soluble protein contents of the leaf limbs in aerated tanks decreased, while peroxidase and catalase activities of roots tissues increased. In spring and summer, effects of aeration on the plants were less than in autumn. Total nitrogen (TN) and ammonia nitrogen (NH4(+)-N) in aerated tanks were lower than in non-aerated tanks, while total phosphorus (TP) and dissolved phosphorus (DP) increased in spring and summer. In autumn, effects of aeration on the plants became more significant. TN, NH4(+)-N, TP and DP became higher in aerated tanks than in non-aerated tanks in autumn. This work provided evidences for regulating aeration techniques based on seasonal variations of the plant physiology in restoring polluted stagnant water.

[Spatial distribution and contamination assessments of heavy metals in sediments of Wenzhou River network].

In order to investigate the spatial distribution pattern and degree of heavy metal pollution in river network sediments of Wenzhou, 29 sediment samples were collected, and using atomic fluorescence spectrometry (AFS) and inductively coupled plasma-optical emission spectrometry (ICP-OES) heavy metal concentration in the samples were analyzed. The Kriging interpolation map reflected the spatial distribution of heavy metal. Comprehensive geo-accumulation index based on the Nemerow index method was established to assess the pollution degree. Pearson correlation analysis method and principal component analysis method were employed in sources analysis. Results show that heavy metal concentration varies significantly at different sites. The area with highest Cd and Zn concentrations is the centralized urban and industrial area of the main stream of this river network, while the highest concentrations of As, Pb, Hg, Cu, Ni and Cr were found to be in machinery industrial park. Sediments are contaminated by Hg, Cd, Cu, Zn, Ni and Cr. The order of degree of contamination is as follows: machinery industrial park > urban areas of the main stream > Sanyang Wetland>outskirt and rural area > drinking water source area. Hg, Cd, Cu, Zn, Ni and Cr have similar pollution sources which are mainly anthropogenic sources.

[Influence of disturbance intensity on nitrogen, phosphorus and permanganate index release of Potamogeton crispus during soaking in water].

Influence of various disturbance intensities on nitrogen, phosphorus and permanganate index (PI) release of Potamogeton crispus were investigated during the plant soaking in water, and the plant materials were collected in an urban lake of Beijing. Results showed that more rapid release of TP and PI from Potamogeton crispus were caused by disturbance, NH4(+) -N and TN in water were significantly increased (ANOVA, p < 0.05) under the condition of high disturbance (120 r/min) for 240 h. However, PI and TP were significantly decreased (ANOVA, p < 0.05) after 240 h disturbance in all treatments. When the release equilibrium of 2.13 g dry mass Potamogeton crispus in one liter of water was reached, the PI, TN, and TP released from unit mass Potamogeton crispus were 35, 5.1 and 4.1 mg x g(-1), respectively. The release ratio of TP from Potamogeton crispus was the highest, while the release ratio of PI was the lowest. The simulated experiment results showed that the highest pollution load to water released from Potamogeton crispus was the TP among the three nutrients. Phosphorus is one of the key factors which causing water eutrophication in lake, thus after submerged plants declining in lake, the field research of phosphorus release and migration from submerged plants into water is the focus of future research work.

[Exploration of relationships between phytoplankton and related environmental factors in the Daning River during sensitive period of algal blooms].

To elucidate relationships between phytoplankton and related environmental factors, phytoplankton and environmental parameters of water quality in the Daning River were conducted using multivariate statistical analysis. Most of the investigated physico chemical parameters [water temperature, total nitrogen, nitrate-N (NO3(-) -N), pH and dissolved oxygen concentration (DO)] in Daning River are significantly different among those sampling sites (ANOVA, p < 0.05). The results indicate that the Daning River has a comparatively high spatial and temporal heterogeneity in the phytoplankton community composition (ANOVA, p < 0.05). The maximum cell density was recorded in Dachang and the minimum density was found at Wuxia-kou sites. Multi-algal species blooms were observed in the same time and place with the maximum density appeared. Correlation analysis was performed to illuminate the relationships between algae density and environmental variables, TN (r = - 0.789, p < 0.05), NO3(-) -N (r = - 0.825, p < 0.05) and NO2(-) -N (r = -0.803, p < 0.05) were negatively correlated with algae density. The results indicate that nitrogen soluble nutrients are key regulatory factors for phytoplankton abundance. The results of redundancy analysis (RDA) indicate that main soluble nutrients (TN, TP, NO3(-)-N and NO2(-)-N), suspended substance (SS) and transparency contributed significantly to phytoplankton community composition. Phytoplankton growth could enhance the pH value. The environmental characterizations and sample sites adjacency contributed significantly to phytoplankton community composition.

[TTC-ETS activity monitoring of A2/O process for combined sewage treatment].

The influences of variations of temperature and F/M on the TTC-ETS activity have been experimentally studied. The correlation between TTC-ETS activity and COD degradation was also analyzed. Comparing TTC-ETS activities with physical and chemical indexes when high C/N ratio impacted A2/O process, the advantages and disadvantages of using TTC-ETS activity to characterize the status of A2/O process were illustrated. The results showed that both temperature and F/M were positively correlated with TTC-ETS activity. TC-ETS activity was in the range of 13.2-48.3 mg/(g x h) and the maximum value was 60 mg/(g x h) which had a significant relationship with COD removal rate. In this system, abnormal state was pre-warned by TTC-ETS activity. The highest removal rate of COD appeared when TTC-ETS activity was 41.0 mg/(g x h).