Effect and its time lags of water level fluctuations in Three Gorges Reservoir on the macroinvertebrates in a tributary bay北大核心CSCD

In order to study how water level fluctuations (WLF) of reservoir influence the macroinvertebrate in tributary bay, we studied the effect of WLF of the Three Gorges Reservior on macroinvertebrate communities in Xiangxi Bay, and the time lags of such effect, based on the surveys in spring and summer from 2005 to 2010. In this research, WLF was represented by water level drawdown (WLD) and the sum of absolute values of rate of water level fluctuations (RWlf). Pearson correlation analysis was used to analyze the relationship between WLF and macroinvertebrates. No significant correlation was found between macroinvertebrates and sum of absolute values of RWLF, while WLD showed significant influence on some biotic parameters. In spring, WLD did not cause significant effect to macroinvertebrates (P > 0.05). In summer, however, the influence was significant, especially in the area of the downstream (XX01 - XX02) of the Xiangxi Bay (P < 0.05). The middle reach of the bay (XX05), located in the conjunction area between Xiangxi Bay and a secondary tributary of the TGR, was also affected significantly (P < 0.05). The relative abundance of Tubificidae declined with the increase of the WLF, while abundance of Chironomidae increased. The time lags of the influence to macroinvertebrates were about 15 days. This analysis indicated that WLF in the mainstream of the reservoir mainly influences the downstream of the tributary bay, and also affects the conjunction area of the secondary tributary. Chironomidae are more tolerant than Tubificidae in water-body with dramatic disturbance, therefore can be considered as the indicator of the effect of summer WLF on macroinvertebrates.     

Growth promotion and disease prevention effects of streptomyces on Amorphophallus konjac K. Koch ex N.E.Br北大核心CSCD

This study aimed to evaluate the disease antagonism and seed growth promotion effects of streptomyces on Amorphophallus konjac by agar block and axenic fermentation extract experiments. Pot experiments were taken to assess relative biocontrol effiency and effect of streptomyce preparation M (mixture of S. carnosus and S. pactum in solid-state fermentation with 1:1 ratio) on biomass, photosynthetic rate, yield and corm quality of A. konjac K. Koch ex N.E.Br. Results showed that: 1 Streptomyces Act12 had obvious antagonistic activity against six soft rot pathogens, and the diameter of growth inhibition zones ranged from 19.4 to 31.6 mm. Fermentation filtrate of streptomyces exhibited growth-promoting activity on melon seed germination and seedling growth. 2 Streptomyce-derived viable preparations had biocontrol effect on A. konjac regarding soft rot-disease prevention. In the pot experiment, individual inoculation of preparations achieved 65.0% relative biocontrol effect on A. konjac during the harvest stage. After 10 and 20 days of inoculation combined with Pectobacterium chrysanthemi (a bacterial pathogen), the relative biocontrol effiency of streptomyces were 100.0% and 58.4%, respectively. 3 Streptomyces showed obvious growth-promoting effect on growth and yield of A. konjac. In the pot experiment, combined inoculation of streptomyces and Pectobacterium chrysanthemi significantly increased the petiole diameter by 11.1%, net photosynthetic rate by 111.7%, fresh weight of corm by 54.8%, fresh weight of rhizome by 304.2%, and the number of rhizomes by 200.0%, compared with individual inoculation of Pectobacterium chrysanthemi. 4 Individual inoculation with streptomyces improved corm quality of A. konjac. The contents of glucomannan, starch and cellulose significantly increased by 14.0%, 8.1% and 27.7%, respectively compared with control (P < 0.05) . This study indicates that streptomyces promotes the growth of A. konjac, enhances the yield and the content of glucomannan, and at the same time helps disease prevention of A. konjac.     

Effects of cyclodextrin on the stereoselectivity inhibition of acetylcholinesterase by isomalathion

ABSTRACT

In attempt to evaluate the effects of cyclodextrins (CDs) on enantioselectivity of chiral pesticides toxicity, this study investigated effects of three kinds of cyclodextrins including α-CD, β-CD and randomly methylated β-CD (RAMEB) on toxicity of four enantiomers of isomalathion including (1R, 3R)-isomalathion, (1S, 3S)-isomalathion, (1S, 3R)-isomalathion and (1R, 3S)-isomalathion. Generally, the addition of α-CD and RAMEB (1.5 g/L to 3.5 g/L concentration) could lead to reduction of isomalathion toxicity in most cases, while the presence of β-CD (0.3 g/L to 1.5 g/L concentration) enhanced the toxicity of isomalathion. It was speculated that higher electronic cloud density and lower water solubility of β-CD than α-CD and RAMEB might favor to combination between acetylcholinesterase (AChE) and isomalathion included by β-CD. With respect for α-CD and RAMEB, isomalathion included by them could be easily dissolved in water because of high water solubility of the two CDs. Therefore, α-CD and RAMEB can be used as remediation regent for the pollution of isomalathion, and β-CD can act as an additive in improving bioactivity of such pesticides. In addition, the presence of CDs can alter enantioselectivity of chiral pesticides. The differences on the extent of enantioselectivity variation of isomalathion induced by α-CD, RAMEB and β-CD might be ascribe to the different cavity, electron cloud density and solubility among the three CDs. In conclusion, the above results gave researchers a possibility to change enantioselectivity of chiral pesticides from undesirable outcomes to desirable ones.     

Effects of temperature on the release of nutrient elements of solid organic materials under conditions of oversaturation

The effects of temperature on the release of chemical components of six solid organic materials under conditions of oversaturation were investigated in this paper. The six materials were peat moss (PM), weathered coals (WC), charred rice husks (CRH), sawdust (Sd), turfgrass clippings (TC), and chicken manure (CM). Significant differences were observed in the available nitrogen and phosphorus content of the aqueous extracts of organic materials at different temperatures. The available nitrogen content in aqueous extracts of PM and WC at 25 °C was higher than that registered at 15 °C and 35 °C. Available nitrogen content in the aqueous extracts of CRH, Sd, TC, and WC at 35 °C was higher than at 15 °C and 25 °C. The available phosphorus content in the aqueous extracts of organic materials at 35 °C was higher than that available at 15 °C and 25 °C, with the exception of Sd. In addition, the release of available phosphorus in the aqueous solution of organic materials at different temperatures varied constantly for 108 h. The release of potassium (K⁺) and sodium (Na⁺) ions in the aqueous extracts of organic materials was basically steady over time, with the exception of CM. High temperature (35 °C) may significantly hasten the release of K⁺ from organic substrates (except for WC) with low temperatures significantly inhibiting release of K⁺ in Sd and CRH. High temperatures (35 °C) might significantly facilitate the release of Na⁺ in CM and TC. However, no significant differences were manifested in the release of Na⁺ from organic substrates at different temperatures, with the exception of CM and TC. Moreover, no significant differences were observed in the release of calcium, magnesium and iron ions with time, nor were there any significant differences in the contents of iron ions in the aqueous extracts of organic materials at different temperatures. The results indicate that multiple mediums should be pretreated in water for a week before being used for planting. They should be used when all mineral elements of organic materials are steady and ignoring the effect of organic mediums.     

Study on the quality and stability of compost through a Demo Compost Plant

This study is concerned with the performance of a Demo Compost Plant for the development of acceptable composting technology in Bangladesh. The Demo Compost Plant was setup at the adjacent area of an existing compost plant located at Khulna city in Bangladesh. Four different composting technologies were considered, where Municipal Solid Waste (MSW) were used as a raw material for composting, collected from the adjacent areas of the plant. Initially the whole composting system was conducted through two experimental setups. In the 1st setup three different types of aerators (horizontal and vertical passively aerator and forced aerator) were selected. For a necessary observation four piles, using only MSW as the input materials in the first three compost pile, the fourth one was the existing Samadhan’s compost pile. Based on the analysis of the experimental findings, the horizontal passively aerated composting technique is suitable for Bangladesh as it had better performance for reducing composting period than that of the others. It was being observed from the quality parameters of compost in the both 1st and 2nd setup that as the waste directly come from kitchen, degradation rate of waste shows a positive result for reducing this waste and there is no possibility of toxic contamination, when it would be used as a soil conditioner. Though there is no significant improvement in the quality of the final product in the 2nd setup as comparing with the 1st setup but it fulfills one of the main objectives of this study is to reduce the whole composting period as well as immediate management of the increasing amount of waste and reducing load on landfill. Selfheating tests reveal that degree of stability of compost with respect to maturation period was remained in the acceptable level, which was further accelerated due to the use of organic additives.     

Online update of model state and parameters of a Monte Carlo atmospheric dispersion model by using ensemble Kalman filter

For an atmospheric dispersion model designed for the assessment of nuclear accident consequences, some uncertain model parameters, such as source term and weather conditions, may influence the reliability of model predictions. In this respect, good estimations of both model state and uncertain parameters are required. In this paper, an ensemble Kalman filter (EnKF) based method for simultaneous state and parameter estimation, using off-site radiation monitoring data, is presented. This method is based on a stochastic state space model, which resembles the parameter errors with stochastic quantities. Three imperfect parameters, including the source release rate, wind direction and turbulence intensity were perturbed simultaneously, and multiple parameter estimation were performed. Having been tested against both simulated and real radiation monitoring data, the method was found to be able to realistically reconstruct the real scene of dispersion, as well as the uncertain parameters. The estimated parameters given by EnKF nicely converge to the true values, and the method also tracks the temporal variation of those parameters.     

Organochlorine pesticide residuals in chickens and eggs at a poultry farm in Beijing, China

Chicken organs, animal feed, droppings, and ambient air were sampled at a farm in Beijing to determine the concentrations of hexachlorocyclohexane isomers (HCHs) and dichlorodiphenyltrichloroethane and metabolites (DDTs). Mean fresh weight concentrations of HCHs and DDTs were 0.122 ± 0.061 ng/g and 0.051 ± 0.038 ng/g in the muscles. These values are 1-2 orders of magnitude lower than those reported in China in 1980. Contaminated feed was the main source of HCHs and DDTs. Only 12.8% of HCH and 3.3% of DDT of the amount consumed were excreted. Accumulated quantities of HCHs and DDTs increased during growth. However, concentrations of HCHs and DDTs did not increase because of dilution from rapid growth. Based on the observed residual levels in mature chicken and the average diet of residents of China, the contributions from chicken and egg consumption to per capita daily intake of HCHs and DDTs were 487% and 88% of those of fish consumption.     

Stoichiometric and molecular evidence for the enrichment of anaerobic ammonium oxidizing bacteria from wastewater treatment plant sludge samples

Anammox enrichments were readily developed from seven municipal wastewater treatment plants (WWTPs) sludge, but not with methanogenic granular sludge from two agro-industrial WWTPs. Only 50 d was required for the first evidence of anammox activity from a return activated sludge obtained from a WWTP operated for nutrient removal. The molar ratios of nitrite and ammonium consumption of approximately 1.32 as well as nitrate and dinitrogen gas product ratios of approximately 0.095 provided evidence of the anammox reaction. The presence of anammox was confirmed by polymerase chain reaction (PCR) using primer sets (PLA46F and AMX820R) specific for anammox bacteria. The 16S rRNA gene fragment of anammox bacteria was detected in seven enrichment cultures (ECs) with demonstrated anammox activity but not in the original inocula from which the ECs were derived and also not in the two methanogenic sludge samples, which indicates the PCR predicted the anammox activity. Two genera, Brocadia and Kuenenia, were successfully identified as the Planctomycetes occurring in the clone libraries of successful anammox enrichments. Brocadia dominated in cultures that were respiked extensively; whereas Kuenenia predominated in cultures that were less aggressively respiked. These findings indicate that respiking management may play an important role on selecting the genus of anammox bacteria. The batch enrichment results clearly illustrate that anammox can be readily enriched from municipal sludge from a wide variety of process operations at WWTPs.     

Characteristics and provenance of dustfall during an unusual floating dust event

This study aims to investigate the characteristics, provenance, and particle-related pollution of an intense dustfall event that occurred in Beijing on 16–17 April 2006. Satellite images reveal that the aeolian dust originated in northeastern Alxa League of Inner Mongolia and passed southeastward across northern Ningxia, middle Inner Mongolia, northern Shaanxi, Shanxi, and Hebei provinces. The dust then moved out of continental China in the vicinity of Beijing and Tianjin. The floating dust led to severe air pollution in Huhhot, Datong, and Beijing. We measured dustfall by collecting dust samples, investigated particle morphology, and calculated the mass medium diameter (MMD) of the dustfall using a scanning electron microscope (SEM). Major elements and mineral content of the dust particles were determined by electron probe and powder X-ray diffractometer, respectively. The relative abundance of dustfall during this event was 12.5–15.0 g m^?2, making up about 10% of the total annual dustfall in Beijing. Dustfall amounted to 205 thousand tons in Beijing, the largest amount observed in recent years. The dust particles were mostly angular, subangular and subrounded in morphology, and the MMD was nearly 12 μm. Particles <10 μm accounted for 54.7% by number, but fine sand particles (larger than 50 μm) made up 53.7% by volume. Particles with diameters larger than 20 μm made up of the predominant volume of the samples (90.35%). Hence, this dustfall event was characterized by a high content of fine sand and coarse silt particles. The principal elements in the dust particles were C, O, Si, Al, Fe, and Ca, whereas the major minerals were quartz, Na-feldspar, calcite, and clay minerals.