Study on fluorescence emission and synchronous-scan fluorescence spectrea of Nitzschia hantzschiana solution with FE(III)

The characterization of the algal Nitzschia hantzschiana solution with (or without) Fe(III) was carried out using fluorescence emission and synchronous-scan spectroscopy. An emission peak (excited at 440 nm) was observed at 675 nm for Nitzschia hantzschiana solution. The effective characterization method used was synchronous-scan fluorescence spectroscopy (SFS). A wavelength difference (Delta lambda) of 90 nm was maintained between excitation and emission wavelengths. The peak was observed at about 236(ex) nm (326(em) nm) for synchronous fluorescence spectroscopy. Fe(III) was an effective quencher. The relationship between I-0/I (quenching efficiency) and c (concentration of Fe (III) added) was a linear correlation for the algal solution with Fe(III). Effects of pH on synchronous-scan fluorescence intensity were evident.

Selective control of toxic Microcystis water blooms using lysine and malonic acid: An enclosure experiment

Three enclosures (10 x 10 x 1.5-1.3 m in depth) were set beside Dianch Lake, Kunming, People's Republic of China, for the period from July 28 to August 26, 2002. The enclosures were filled with cyanobacterial (Microcystis aeruginosa) water bloom-containing lake water. Lake sediment that contained macrophytes and water chestnut seeds was spread over the entire bottom of each enclosure. Initially, 10 g/m(2) of lysine was sprayed in Enclosure B, and 10 g/m(2) each of lysine and malonic acid were sprayed together in Enclosure C. Enclosure A remained untreated and was used as a control. The concentrations of lysine, malonic acid, chlorophyll a, and microcystin as well as the cell numbers of phytoplankton such as cyanobacteria, diatom, and euglena were monitored. On day 1 of the treatment, formation of cyanobacterial blooms almost ceased in Enclosures B and C, although Microcystis cells in the control still formed blooms. On day 7 Microcystis cells in Enclosure B that had been treated with lysine started growing again, whereas growth was not observed in Microcystis cells in Enclosure C, which had been treated with lysine and malonic acid. On day 28 the surface of Enclosure B was covered with water chestnut (Trapa spp.) and the Microcystis blooms again increased. In contrast, growth of macrophytes (Myriophllum spicatum and Potamogeton crispus) was observed in Enclosure C; however, no cyanobacterial blooms were observed. Lysine and malonic acid had completely decomposed. The microcystin concentration on day 28 decreased to 25% of the initial value, and the pH shifted from the initial value of 9.2 to 7.8. We concluded that combined treatment with lysine and malonic acid selectively controlled toxic Microcystis water blooms and induced the growth of macrophytes. (c) 2005 Wiley Periodicals, Inc.

Nonylphenol, bisphenol-A and DDTs in Lake Donghu, China

A preliminary survey was carried out in April 2003 to estimate the levels of nonylphenol (NP), bisphenol-A (BPA) and residual DDTs in Lake Donghu. After then, the sediments of some areas of the lake were moved out for clearing the lake by the local government. Therefore, the variance of NP and BPA after the clearance of sediment in the surface water was determined from December 2003 to May 2004. Sediments, surface water and fish were collected from four sub-lake areas and the analytes were qualified by GC/MS in SIM mode after concentration onto an Oasis solid phase extraction cartridge. NP and BPA values ranged between 5.46-119.10 and 0.9913.42 mg/kg dw, respectively, in sediments, 75.2-179.6 and 15.1-62.5 mu g/L in surface water. Meanwhile, the bioaccumulation factors (BCFs) of NP and BPA were calculated in fish livers. Plasma vitellogenin (VTG), a sensitive biomarker showing oestrogenicity was detected in the captured male Wuchang bream (Megalobrama amblycephala Yih) and common carp (Cyprinus carpio). After sediment clearance, the concentrations of NP and BPA decreased to 0.65-25.04 and 0.04-21.32 mu g/L. The results indicate the presence of high-dose xenoestrogenic NP and BPA, probably major contributors which associate with VTG induction in Lake Donghu male fish.

Biomarker responses and reproductive toxicity of the effluent from a Chinese large sewage treatment plant in Japanese medaka (Oryzias latipes)

The present study was conducted to assess the potential toxicity of the effluent from a large sewage treatment plant (GBD-STP) in Beijing. Japanese medakas (Oryzias latipes) at reproduction active period were exposed to a serial of graded concentrations of the effluent or 100 ng l(-1) of 17-alpha-ethinylestradiol (EE2, positive control). Growth, gonadosomatic index (GSI), hepatosomatic index (HSI), reproductive success, induction potency of vitellogenin (VTG) in male fish and that of 7-ethoxyresorufin-o-deethylase activity (EROD) in male fish liver were used as test endpoints. The growth suppression of fish was observed in a dose-dependent manner, resulting in significant differences in both body length and body weight of medaka above 5% effluent. This effluent can inhibit the growth of gonad of medakas and are more sensitive to male than to female. At exposure concentration of 40% and higher, there was an unexpected decrease of HSI values, which may be resulted from sub-lethal toxicity of effluent to fish liver. VTG of plasma in males were induced in all exposure concentration levels, but not in a dose-dependent manner. The concentration of 5% effluent would be the lowest observed adverse effect level (LOAEL) affecting reproductive success when examining fertile individuals, fecundity and fertilization rate. The overt CYP1A response and higher reproductive toxicity may be indicative of low process efficiency of this STP. (c) 2004 Elsevier Ltd. All rights reserved.