Studies on the adsorption equilibrium and kinetics of pentachlorophenol on suspended particulate matter of Donghu Lake water

In this paper, the adsorption equilibrium and kinetic behaviors of pentachlorophenol (PCP) on suspended particulate matter (SPM) in Donghu Lake water were investigated. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms and their constants were evaluated. The results indicated that the adsorption of PCP on Donghu Lake SPM followed the Freundlich isotherm. Furthermore, the first order Lagergren rate equation and the pseudo-second order rate equation were used to describe the kinetic behaviors of PCP adsorption on Donghu Lake SPM, the rate constants were determined, and the kinetic process of the adsorption of PCP on Donghu Lake SPM followed the second order kinetic model.

Bioaccumulation of the hepatotoxic microcystins in various organs of a freshwater snail from a subtropical Chinese lake, Taihu lake, with dense toxic microcystis blooms

In this paper, we describe the seasonal dynamics of three common microcystins (MCs MC-RR, MC-YR, and MC-LR) in the whole body, hepatopancreas, intestine, gonad, foot, remaining tissue, and offspring of a freshwater snail, Bellamya aeruginosa, from Gonghu Bay of Lake Taihu, China, where dense toxic Microcystis blooms occur in the warm seasons. Microcystins were determined by liquid chromatography electrospray ionization mass spectrum. Microcystin (MC-RR + MC-YR + MC-LR) content of the offspring and gonad showed high positive correlation, indicating that microcystins could transfer from adult females to their young with physiological connection. This study is the first to report the presence of microcystins in the offspring of the adult snail. The majority of the toxins were present in the intestine (53.6%) and hepatopancreas (29.9%), whereas other tissues contained only 16.5%. If intestines are excluded, up to 64.3% of the toxin burden was allocated in the hepatopancreas. The microcystin content in the intestine, hepatopancreas, and gonad were correlated with the biomass of Microcystis and intracellular and extracellular toxins. Of the analyzed foot samples, 18.2% were above the tolerable daily microcystin intake recommended by the World Health Organization (WHO) for human consumption. This result indicates that public health warnings regarding human ingestion of snails from Taihu Lake are warranted. In addition, further studies are needed to evaluate the occurrence by Microcystis in relation to spatial and temporal changes in water quality.

In situ studies on the bioaccumulation of microcystins in the phytoplanktivorous silver carp (Hypophthalmichthys molitrix) stocked in Lake Taihu with dense toxic Microcystis blooms

The phytoplanktivorous silver carp is an important biomanipulation fish to control cyanobacterial blooms and is also a food fish with the greatest production in China. The accumulation of the hepatotoxic microcystins (MCs) determined by LC-MS in various organs of silver carp was studied monthly in Lake Taihu dominated by toxic Microcystis aeruginosa. Average recoveries of spiked fish samples were 78% for MC-RR and 81% for MC-LR. The highest content of MCs was found in the intestine (97.48 mu g g(-1) DW), followed by liver (6.84 mu g g(-1) DW), kidney (4.8 8 mu g g(-1) DW) and blood (1.54 mu g g(-1) DW), and the annual mean MC content was in the order of intestine > liver > kidney > blood > muscle > spleen > gallbladder > gill. Silver carp could effectively ingest toxic Microcystis cells (up to 84.4% of total phytoplankton in gut contents), but showed fast growth (from 141 g to 1759 g in I year in mean weight). Silver carp accumulated less microcystins in liver than other animals in the same site or other fish from different water bodies at similar level of toxin ingestion. There was possible inhibition of the transportation of the most toxic MC-LR across the gutwall. Muscle of silver carp in Lake Taihu should not be consumed during period of dense Microcystis blooms while viscera were risky for consumption in more months. (c) 2006 Elsevier B.V. All rights reserved.

Effects of dissolved organic matter on the growth and pigments synthesis of Spirulina platensis (Arthrospira)

Excessive accumulation of dissolved organic matter (DOM) in the culture ponds of Spirulina platensis is usually considered to be one of the potential factors affecting the production of S. platensis, however, we are not quite aware of effects of DOM on the growth and pigments synthesis of S. platensis. In the present study, S. platensis was grown in batch or semi-continuous cultures using the filtrate in the culture ponds that had not been renewed for years. It was found that disssolved organic carbon up to 60 mg/L did not bring about an inhibitory effect on the growth of S. platensis, but increased the contents of chlorophyll a and phycocyanin instead. However, further accumulation of dissolved organic matter could decrease the content of chlorophyll a.

Attenuation of photosynthetically available radiation by chlorophyll, chromophoric dissolved organic matter, and tripton in lake Donghu, China

The attenuation coefficient of photosynthetically available radiation [K-d(PAR)] and three water quality parameters [chlorophyll a (chl a)], chromophoric dissolved organic matter (CDOM) and tripton] were measured at three stations in shallow, subtropical Lake Donghu from April 2003 to March 2004. The multiple regression equation of K-d(PAR) versus chl a, CDOM, and tripton was: K-d(PAR) = 0.44 + 0.019 chl a + 1.88 CDOM + 0.016 tripton, which revealed the relative contributions of the three parameters to K-d(PAR). The effects of water and CDOM on K-d(PAR) were of minor importance (19-26%), while chl a and tripton were the two greatest contributors, accounting collectively for 74-81%.

Differing estrogen activities in the organic phase of air particulate matter collected during sunny and foggy weather in a Chinese city detected by a recombinant yeast bioassay

Total air suspended particles (PM 100) collected from an urban location near a traffic line in Wuhan, China, were examined for estrogen using a recombinant yeast bioassay. Wuhan, located at the central part of China, is the fourth biggest city in China with 7 million populations. Today, Wuhan has developed into the biggest city and the largest traveling center of central China, becoming one of the important bases of industry, education and research. Wuhan is right at the confluent point of Yangzi River, the third longest river in the world, and its largest distributary Hanjiang, with mountains and more than 100 takes in downtown area. Therefore, by its unique landscape, Wuhan has formed clear four seasons with relatively long winter and summer and short spring and autumn. Foggy weather usually happen in early spring. The yeast line used in this assay stably expresses human estrogen receptor-alpha. Weak but clear estrogenic activities were detected in the organic phase of crude extracts of air particle materials (APM) in both sunny and foggy weather by 0.19-0.79 mug E2/gPM(100) which were statistically significantly elevated relative to the blank control responding from 20% to 50% of the maximum E2 response, and the estrogenic activity was much higher in foggy weather than in sunny weather. The estrogenic activities in the sub-fractions from chromatographic separation of APM sampled in foggy days were also determined. The results indicated that the responses of the fractions were obviously higher than the crude extracts. Since there is no other large pollution source nearby, the estrogenic material was most likely from vehicle emissions, house heating sources and oil fumes of house cooking. The GC/MS analysis of the PM100 collected under foggy weather showed that there were many phenol derivatives, oxy-PAHs and resin acids which have been reported as environmental estrogens. These results of the analysis of estrogenic potency in sunny and foggy weather in a subtropical city of China indicate that further studies are required to investigate the actual risks for the associated health and atmospheric system. (C) 2004 Elsevier Ltd. All rights reserved.

The vertical microdistribution of cyanobacteria and green algae within desert crusts and the development of the algal crusts

Substantial amounts of algal crusts were collected from five different desert experimental sites aged 42, 34, 17, 8 and 4 years, respectively, at Shapotou ( China) and analyzed at a 0.1 mm microscale of depth. It was found that the vertical distribution of cyanobacteria and microalgae in the crusts was distinctly laminated into an inorganic-layer (ca. 0.00 - 0.02 mm, with few algae), an algae-dense-layer ( ca. 0.02 - 1.0 mm) and an algae-sparse-layer ( ca. 1.0 - 5.0 mm). It was interesting to note that in all crusts Scytonema javanicum Born et Flah ( or Nostoc sp., cyanobacterium), Desmococcus olivaceus (Pers ex Ach., green alga) Laundon and Microcoleus vaginatus Gom. ( cyanobacterium) dominated at the depth of 0.02 - 0.05, 0.05 - 0.1 and 0.1 - 1.0 mm, respectively, from the surface. Phormidium tenue Gom. ( or Lyngbya cryptovaginatus Schk., cyanobacterium) and Navicula cryptocephala Kutz.( or Hantzschia amphioxys (Ehr.) Grun. and N. cryptocephala together, diatom) dominated at the depth of 1.0 - 3.0 and 3.5 - 4.0 mm, respectively, of the crusts from the 42 and 34 year old sites. It was apparent that in more developed crusts there were more green algae and the niches of Nostoc sp., Chlorella vulgaris Beij., M. vaginatus, N. cryptocephala and fungi were nearer to the surface. If lichens and mosses accounted for less than 41.5% of the crust surface, algal biovolume was bigger when the crust was older, but the opposite was true when the cryptogams other than algae covered more than 70%. In addition to detailed species composition and biovolume, analyses of soil physicochemical properties, micromorphologies and mineral components were also performed. It was found that the concentration of organic matter and nutrients, electric conductivity, silt, clay, secondary minerals were higher and there were more micro-beddings in the older crusts than the less developed ones. Possible mechanisms for the algal vertical microdistribtion at different stages and the impact of soil topography on crust development are discussed. It is concluded that biomethods ( such as fine species distribution and biovolume) were more precise than mineralogical approaches in judging algal crust development and thus could be a better means to measure the potentiality of algal crusts in desert amelioration.

Enhancement of planktonic rotifers by Microcystis aeruginosa blooms: An enclosure experiment in a shallow eutrophic lake

Enclosure experiments with three treatments (sediment addition, sediment + nitrogen enrichment, sediment + phosphorus enrichment) and unfertilized controls were performed in shallow hypereutrophic Lake Donghu during the summer of 2000. Dense Microcystis aeruginosa blooms occurred in all the enclosures during the experimental period but not in the surrounding lake water. Generally, the dominant rotifers were Polyarthra vulgalis, Filinia longiseta, Proales sp. and Asplanchna sp. at the beginning of the experiment, followed by a shift to Brachionus calyciflorus, Trichocerca similis, Cephalodella catellina and Anuraeopsis fissa, and finally to F. longiseta, Proales sp. and Keratella cochleris. M. aeruginosa blooms strongly suppressed the larger Diaphanosoma brachyurum but enhanced the development of the smaller cladocerans and rotifers that probably efficiently utilized organic matter from M. aeruginosa through the detritus food chain. The smaller cladoceran and rotifers coexisted successfully throughout the experimental period.

Radiation-matter oscillations in attosecond polarization beats using twin color-locked noisy lights

Based on the phase-conjugate polarization interference between two one-photon processes. When the laser has broadband linewidth, the sum-frequency polarization beat (SFPB) signal shows the autocorrelation of SFPB exhibits hybrid radiation-matter detuning terahertz damping oscillation. As an attosecond ultrafast modulation process, it can be extended intrinsically to any sum-frequency of energy-levels. It hits been also found that the asymmetric behaviors of the polarization beat signals result from the unbalanced dispersion effects, (c) 2005 Elsevier B.V. All rights reserved.