Phytotoxicity of thiourea application on soybean seedlings北大核心CSCD

For a precise evaluation of environmental and eco-toxicology effect of nitrification inhibitor on agroecosystem, the phytotoxicity of nitrification inhibitor should be fully understand. This paper aimed to study the phytotoxicity of thiourea and urea application on soybean seedlings. Effects of thiourea on the biomass, content of metal ions and chlorophyll level were studied in the leaves of soybean, and the effects of thiourea on anti-oxidative system (SOD, POD, and CAT) and content of MDA in the leaves of soybean were also investigated. The results showed that thiourea had great impact on the growth of soybean. Low concentration (1.0 mmol kg-1) of thiourea could slightly inhibit the growth of seedlings, and increase the activities of SOD, POD, CAT. Thiourea treatment of different concentrations had no effect on the content of Cu and Zn ion in soybean seedlings, but could obviously change the content of Mn and Fe ions in soybean seedlings. The content of Mn ion increased with the concentration of thiourea, from 18.58 mg kg-1 in the control to 45.45 mg kg-1 with 5 mmol kg-1 thiourea treatment. On the other hand, the content of Fe ion decreased with the concentration of thiourea, from 20.77 mg kg-1 in the control to 17.63 with 5 mmol kg-1 thiourea treatment. Heave inhibition effects and phytotoxic symptom were found in thriourea treatment of 5.0 mmol kg-1. The growth of seedlings was obviously inhibited; the content of chlorophyll in leaves of soybean decreased to 2.11 mg kg-1 compared to 3.56 mg kg-1 in that of the control. Simultaneously, the activities of SOD, POD, CAT and the content of MDA increased dramatically when thiourea reached 5.0 mmol kg-1. The heave inhibition effects and phytotoxic symptom in the soybean seedling indicated that thiourea could induce environmental stress in the seedlings.     

Chemical composition and physical properties of filter fly ashes from eight grate-fired biomass combustion plants

For the handling, treatment and utilization of fly ash from biomass combustion its chemical composition and physical properties are important. In this study eight filter fly ashes from different grate-fired biomass combustion plants were investigated. In fly ash from straw combustion high concentrations of(K) were found, whereas in the fly ash from wood combustion the concentrations of Ca and Mg were higher. The average concentration of PO3-4was similar in both types of fly ashes. In all wood fly ashes some measured heavy metal concentrations were above the limits for utilization. The straw fly ashes were much less contaminated and can be utilized. For wood fly ash most parameters showed little variation, except from one fly ash where the dust pre-separator is in poor condition. The average values were: mass median diameter 4.3 ± 0.8 μm, spread of particle size distribution19 ± 11, particle density 2620 ± 80 kg/m3 and angle of repose 50°± 1°. The density of the straw fly ashes is lower(2260 ± 80 kg/m3) and the spread of the size distribution is higher(72 ± 24).For one straw combustion fly ash the values of the mass median diameter and the angle of repose were similar to the values of wood combustion fly ash, for the other straw fly ash the values differed considerably. While the particle size of this fly ash was much smaller,surprisingly the angle of repose was also lower. This can be attributed to the formation of small agglomerates in this fly ash, which were not disintegrated without a certain stress.     

Mg2+ improves biomass production from soybean wastewater using purple non-sulfur bacteria

Soybean wastewater was used to generate biomass resource by use of purple non-sulfur bacteria(PNSB). This study investigated the enhancement of PNSB cell accumulation in wastewater by Mg2+under the light-anaerobic condition. Results showed that with the optimal Mg2+dosage of 10 mg/L, biomass production was improved by 70% to 3630 mg/L,and biomass yield also was improved by 60%. Chemical Oxygen Demand(COD) removal reached above 86% and hydraulic retention time was shortened from 96 to 72 hr. The mechanism analysis indicated that Mg2+could promote the content of bacteriochlorophyll in photosynthesis because Mg2+is the bacteriochlorophyll active center, and thus improved adenosine triphosphate(ATP) production. An increase of ATP production enhanced the conversion of organic matter in wastewater into PNSB cell materials(biomass yield) and COD removal, leading to more biomass production. With 10 mg/L Mg2+, bacteriochlorophyll content and ATP production were improved by 60% and 33% respectively.     

Enhancement of Rhodobacter sphaeroides growth and carotenoid production through biostimulation

Bacillus thuringiensis/cereus L2 was added as a biostimulant to enhance the biomass accumulation and carotenoid yield of Rhodobacter sphaeroides using wastewater as the culturing medium. Results showed that biostimulation could significantly enhance the R. sphaeroides biomass production and carotenoid yield. The optimal biostimulant proportion was 40 μL(about 6.4 × 105CFU). Through the use of biostimulation, chemical oxygen demand removal, R. sphaeroides biomass production, carotenoid concentration, and carotenoid yield were improved by 178%, 67%, 214%, and 70%, respectively. Theoretical analysis revealed that there were two possible reasons for such increases. One was that biostimulation enhanced the R. sphaeroides wastewater treatment efficiency. The other was that biostimulation significantly decreased the peroxidase activity in R. sphaeroides. The results showed that the highest peroxidase activity dropped by 87% and the induction ratio of the RSP_3419 gene was 3.1 with the addition of biostimulant. The enhanced carotenoid yield in R. sphaeroides could thus be explained by a decrease in peroxidase activity.     

Effects of temperature and composite alumina on pyrolysis of sewage sludge

An interactive dual-circulating fluidized bed system has been proposed in which the pyrolysis of sewage sludge(SS) and incineration of biomass proceed simultaneously, and alumina is used as the bed material and heat carrier. The alumina coated with biomass ash would mix with sewage sludge in the pyrolysis reactor of this device. It is important to know the influence of composite alumina(CA) on the pyrolysis progress. Sewage sludge was pyrolyzed in a fixed bed reactor from 400 to 600°C using CA as catalyst. The effects of temperature and CA additive ratio on the products were investigated. The product yields and component distribution of non-condensable gas were more sensitive to the change of temperature, and the maximum liquid yield of 48.44 wt.% and maximum Useable Energy of Liquid of 3871 k J/kg sludge were observed at 500°C with 1/5 CA/SS(mass ratio). The gas chromatography–mass spectrometry results showed that the increase of temperature enhanced devolatilization of organic matter and promoted cyclization and aromatization of aliphatics. The presence of CA could strengthen secondary cracking and interaction among primary products from different organic compounds, such as acid–amine condensation,and reduce the content of oxygenated compounds. When the CA additive amount exceeded a certain proportion, the aromatization was clearly strengthened. The effects of CA on decomposition of fatty acids and formation of aromatics were similar to that of temperature. This means that the reaction temperature could be lowered by introducing CA, which has a positive effect on reducing energy consumption.     

Salinity influence on soil microbial respiration rate of wetland in the Yangtze River estuary through changing microbial community

Estuarine wetland, where freshwater mixes with salt water, comprises different regions（rivers and marine ecosystems） with significantly varying tidal salinities. Two sampling areas, ZXS and JS, were selected to investigate the effect of tidal salinity on soil respiration（SR）. ZXS and JS were located in Zhongxia Shoal and Jiangyanan Shoal of Jiuduansha Wetland respectively, with similar elevation and plant species, but significantly different in salinity. The results showed that with almost identical plant biomass, the SR and soil microbial respiration（SMR） of the tidal wetland with lower salinity（JS） were significantly higher than those of the tidal wetland with higher salinity（ZXS）（p 〈 0.05）. However, unlike SMR and SR, the difference in the soil microbial biomass（SMB） was not significant（p 〉 0.05）with the SMB of ZXS a little higher than that of JS. The higher SMR and SR of JS may be closely connected to the soil microbial community structures and amount of dominant bacteria. Abundant β- and γ-Proteobacteria and Actinobacteria in JS soil, which have strong heterotrophic metabolic capabilities, could be the main reason for higher SMR and SR,whereas a high number of ε-Proteobacteria in ZXS, some of which have carbon fixation ability, could be responsible for relatively lower carbon output. Path analysis indicated that soil salinity had the maximum negative total influencing coefficient with SMR among the various soil physical and chemical factors, suggesting that higher soil salinity, restricting highly heterotrophic bacteria, is the principle reason for lower SMR and SR in the ZXS.     

新疆生物质能资源的经济效益分析与评价

生物质能资源具有可再生和环境友好的双重属性,现已成为新疆能源发展的重要组成部分。对新疆生物质能资源进行总量估算,分析其地区分布特点,运用替代价值法分别计算秸秆、牲畜粪便及能源植物三大类生物质能资源的经济效益,并从结果中分析得出,新疆生物质能资源在区域分布上具有资源分布不均、＂西高东低＂以及效益高低与自然条件关联性大等特征。因此,新疆在发展生物质能源产业时应当因地制宜,才能最大限度将区域资源优势转化为经济优势。     

退化梭梭林禁牧封育周期的研究

对阿拉善荒漠地区不同时间（2005年、2002年、1999年和1980年）禁牧围封梭梭生态特征进行了对比研究。生态特征分析表明7年封育梭梭恢复效果最好,梭梭盖度达到了22．6％,密度增加到每公顷594株,生物量提高到每公顷12．01吨。而25年围封梭梭林密度、盖度和生物量均低于7年封育。年龄结构分析表明1年、4年和7年禁牧封育梭梭均发展趋势,而25年禁牧封育梭梭呈现衰退趋势。动态模拟分析表明通过禁牧封育,干旱区退化梭梭林恢复最佳周期14年,生物量达15．3吨／公顷,盖度28％,密度高达770彬公顷。     

Effects of tracked vehicle activity on bird populations

This study was initiated to develop cause and effect relationships between Army training activities and bird populations throughout the continental United States. Installations in Kentucky, Louisiana, Texas, and Washington were selected as representative of diverse ecosystems and of extent of training. Birds were separated into 31 guilds to assist in the analysis between different ecosystems. The results showed that (1) guild theory can be useful in impact analyses within and between ecosystems, (2) tracked vehicles disturb bird populations because of habitat alteration and reduction, (3) the change in biomass ranged from 20.9to–55.3 percent and is dependent on the extent of training and ecosystem type, and (4) species replacement should be a major concern, with nine endemic species being replaced by three endemic and two introduced species. Because of similarities between tracked vehicle training and some construction activities, much of this information may be useful for analysis of civilian activities as well as military.     

Total recycling of CCA treated wood waste by low-temperature pyrolysis

A system to turn a potentially harmful stream of solid waste into a set of substreams with either commercial value or highly concentrated residual streams is presented. The waste which is considered is metal impregnated (in particular Chromated Copper Arsenate (CCA) treated) wood waste and timber, such as telephone poles, railway sleepers, timber from landscape and cooling towers, wooden silos, hop-poles, cable drums and wooden playground equipment. These waste streams sum up to several 100,000 tons of material per year currently to be dumped in every major country of the European Community (EC). Technologies need to be developed to reduce this CCA treated wood waste, such that all of the metals are contained in a marketable product stream, and the pyrolysis gases and/or pyrolysis liquid are used to their maximum potential with respect to energy recuperation. Pyrolysing the CCA treated wood waste may be a good solution to the growing disposal problem since low temperatures and no oxidising agents are used, which result in lower loss of metals compared to combustion. An experimental labscale pyrolysis system has been developed to study the influence of the pyrolysis temperature and the duration of the pyrolysis process on the release of metals and the mass reduction. The macrodistribution and microdistribution of the metals in the solid pyrolysis residue is studied using Inductively Coupled Plasma Mass Spectrometry (ICP–MS) and Scanning Electron Microscopy coupled with Energy Dispersive X-ray Analysis (SEM–EDXA). Furthermore, a complete mass balance is calculated over the pyrolysis system. Based on these results a semi-industrial pyrolysis system (pilot plant scale) has been developed consisting of three stages: grinding, packed bed pyrolysis and metal separation. Special types of equipment have been developed to carry out the three stages. A new grinding system has been developed, based on a crushing mechanism rather than a cutting mechanism. The crushed wood is introduced by means of a screw feeding system into a reaction column. In this pyrolysis reactor the wood is heated by subjecting it to a flow of hot gases. This causes an adiabatic pyrolysis, which results in volatilisation of the volatile compounds whereas the mineral compounds (containing the metals) remain entrapped in a coal-type residue which is very rich in carbon. The condensable compounds in the pyrolysis gas condense while leaving the reaction zone due to the inverse temperature gradient. The pyrolysis gas leaving the reactor is used as fuel for the hot gas generator. The charcoal which is extracted at the bottom of the reactor, is cooled, compressed, removed and stored, ready to feed the subsequent stage. A specially developed grinder is used to remove the metal particles from the charcoal and the separation between metal and charcoal particles is accomplished in a pneumatic centrifuge as a result of the difference in density. Using this system the ultimate waste is less than 3% of the initial wood mass. Results obtained with a semi-industrial scale prototype confirm the effectiveness of the process.