Comparative analysis of water quality and toxicity assessment methods for urban highway runoff.

In this study, comparative analyses of highway runoff samples obtained from seventeen storm events have been conducted between the traditional water quality assessment method and biotoxicity tests, using zebrafish (Danio rerio) embryos and luminous bacteria (Vibrio qinghaiensis. Q67) to provide useful information for ecotoxicity assessment of urban highway runoff. The study results showed that the Nemerow pollution index based on US EPA recommended Criteria Maximum Concentrations (CMC) (as traditional water quality assessment method) had no significant correlation with luminous bacteria acute toxicity test results, while significant correlation has been observed with two indicators of 72 hpf (hours post fertilization) hour hatching rate and 96 hpf abnormality rate from the toxicity test with zebrafish embryos. It is therefore concluded that the level of mixture toxicity of highway runoff could not be adequately measured by the Nemerow assessment method. Moreover, the key pollutants identified from the water quality assessment and from the biotoxicity evaluation were not consistent. For biotoxic effect evaluation of highway runoff, three indexes were found to be sensitive, i.e. 24 hpf lethality and 96 hpf abnormality of zebrafish embryos, as well as the inhibition rate for luminous bacteria Q67. It is therefore recommended that these indexes could be incorporated into the traditional Nemerow method to provide a more reasonable evaluation of the highway runoff quality and ecotoxicity.

Effects of dissolved organic matter from a eutrophic lake on the freely dissolved concentrations of emerging organic contaminants.

The authors studied the effects of dissolved organic matter (DOM) on the bioavailability of bisphenol A (BPA) and chloramphenicol by measuring the freely dissolved concentrations of the contaminants in solutions containing DOM that had been isolated from a mesocosm in a eutrophic lake. The abundance and aromaticity of the chromophoric DOM increased over the 25-d mesocosm experiment. The BPA freely dissolved concentration was 72.3% lower and the chloramphenicol freely dissolved concentration was 56.2% lower using DOM collected on day 25 than using DOM collected on day 1 of the mesocosm experiment. The freely dissolved concentrations negatively correlated with the ultraviolent absorption coefficient at 254 nm and positively correlated with the spectral slope of chromophoric DOM, suggesting that the bioavailability of these emerging organic contaminants depends on the characteristics of the DOM present. The DOM-water partition coefficients (log KOC ) for the emerging organic contaminants positively correlated with the aromaticity of the DOM, measured as humic acid-like fluorescent components C1 (excitation/emission=250[313]/412 nm) and C2 (excitation/emission=268[379]/456 nm). The authors conclude that the bioavailability of emerging organic contaminants in eutrophic lakes can be affected by changes in the DOM.

[Temporal and spatial distribution of environmental factors and chlorophyll-a and their correlation analysis in a small enclosed lake].

About four year's field observation was conducted from July 2007 to September 2011, in a small enclosed eutrophic lake located in Qianwei Village, Chongming Island. The temporal and spatial distribution of environmental factors (including physical-chemical factors and hydrodynamic condition) and chlorophyll-a (Chl-a) were studied and their correlation was analyzed. Results indicated that there were significant differences in the spatial and temporal distribution of Chl-a in the lake. Significantly positive correlation was found between Chl-a and water temperature, turbidity, TN and TP. Water temperature and nutrients were the main limited factors of seasonal changes of phytoplankton. It could be the result of phytoplankton growth that caused the seasonal change of turbidity. It was found that hydrological changes were the primary factor affecting the spatial difference of Chl-a concentration. Lower average Chl-a concentration (35. 30 microg.L-1) was recorded in the north watercourse, in condition with higher wind driven flow velocity ranging from 0. 08 m.s- 1 to 0. 22 m.s -1. A strong negative correlation was found between Chl-a concentration and flow velocity. Higher average Chl-a concentration (53. 11 microg.L-1) was frequently found under flow conditions ranged from 0 m.s-1 to 0. 10 m.s-1. These findings indicated that increasing hydrodynamic condition would significantly inhibit the growth of phytoplankton and reduce the risk of algae blooming in summer in these eutrophic water bodies.

[Study on the spiral CT reconstruction in the diagnosis and treatment of pelvic ring fractures].

OBJECTIVE: To investigate the clinical value of spiral CT with multi-planar reconstruction (MPR) and three diamensions reconstruction (3D) in the diagnosis and treatment of pelvic ring fractures. METHODS: Fifty-seven patients with pelvic ring fractures were examined with digital radiography and spiral CT in our hospital from April 2004 to April 2009. According to Tile classification, there were thirty-eight cases in type A, twelve in type B and seven in type C. Expectant treatment was used in type A, while surgery, open reduction internal fixation or percutaneous lag screw internal fixation technique for sacroiliac joint due to the displacement of fractures, for type B and C. Three days to twenty-seven months after operation, spiral CT examinations were used to evaluate the location of internal fixation. Cross-check analysis of images of digital radiography and spiral CT was performed before and after operation. RESULTS: Five posterior and three anterior pelvic ring fractures were diagnosed as suspected fractures. Nine posterior and three anterior pelvic ring fractures were missdiagnosed according to plain radiographs, which were corrected by spiral CT examination. According to the postoperative imageology evaluation, the results were excellent in 15, good in 3 and bad in 1. According to clinical evaluation, 16 cases were excellent, 3 good. CONCLUSION: Spiral CT with multi-planar reconstruction (MPR) and three diamensions reconstruction (3D) has clinical values for precise diagnosis and treatment for the complex pelvic ring fractures.

[Enclosure experiments about the hydrodynamics effects on the plankton].

To explore the effects of hydrodynamics on plankton, four kinds of surface flow enclosure experiments were done from August, 2007 to July, 2008. The flow velocity were 0.002, 0.10, 0.15 and 0.30 m x s(-1) respectively. Under 0.15 and 0.30 m x s(-1) surface velocity conditions, it was revealed that Spirogyra biomasses were 2.3 times and 31.3 times of the ones under static state respectively. Under 0.10, 0.15 and 0.30 m x s(-1) conditions, Chl-a concentrations were 45%, 54% and 26% of the ones under statistic state while zooplankton biomasses were 38%, 27% and 6% respectively. The mechanism is that a certain flow velocity stimulates Spirogyra growth may be for the shear stress generated by the surface flow can help the vegetative reproduction. Shear stress and turbulence may also bring the phytoplankton to the light limited area by force. Besides, as Spirogyra grows well, it can inhibit the phytoplankton growth by excretion or some symbiotic microorganism. When shear stress or water turbulence exceeds a certain value, crustacean zooplankton successful grazing rate may also be depressed.