Assessment of the relative agronomic effectiveness of phosphate rocks under glasshouse conditions

Six phosphate rocks (PRs) of varying reactivities were compared with monocalcium phosphate (MCP) in a glasshouse experiment growing perennial ryegrass (Lolium perenne cv. Nui) as the test plant on four soils of contrasting P sorption capacity and exchangeable Ca. The cumulative dry matter yield over 10 harvests showed a significant response to P application in all soils. Based on relative yield and P uptake, MCP was the most effective P fertilizer followed by the reactive phosphate rocks, which were superior to the unreactive rocks in all soils. The relative agronomic effectiveness (RAE) and substitution ratio (SR) of individual PR fertilizers, calculated with respect to MCP using the methods of vertical and horizontal comparison, respectively, were similar over a range of fertilizer rate. There was a decline or slight increase in the performance of PRs with time in the low P sorption soils but a consistent increase in the high P sorption soils. Some initial influence of exchangeable Ca content of the soils on the relative performance of PRs was also observed. Generally the PRs performed better in high P sorption soils than low P sorption soils and in low exchangeable Ca soils than high exchangeable Ca soils.     

Evaluation of the performance of tight-UF membranes with respect to NOM removal using effective MWCO, molecular weight, and apparent diffusivity of NOM

Concepts for the effective MWCO of tight-UF membranes, and apparent diffusion coefficients for NOM, were introduced to determine the mechanisms influencing NOM removal and to explain the various behaviors of NOM removal by UF membranes with different hydrophobicities, permeability, and surface charges. Colloidal NOM (COM) and non-colloidal hydrophobic NOM (NCD HP) constituents were chosen for the evaluation of two different UF membranes. For a relatively hydrophobic, relatively high permeability, and less negatively charged UF membrane, the hydrophobic fractions of COM were preferentially removed and were also removed by a size exclusion mechanism (i.e., both hydrophobic interaction and size exclusion mechanisms). The NCD HP exhibited no such preferential removal of the hydrophobic fractions, but could be removed by a size exclusion mechanism (i.e., only size exclusion mechanism). With a relatively hydrophilic, relatively low permeability, and more negatively charged UF membrane, COM exhibited no preferential removal of the hydrophobic fractions, but could be removed by a size exclusion mechanism (i.e., only size exclusion mechanism). Whereas the hydrophobic fractions of the NCD HP were preferentially removed, these could not be removed by a size exclusion mechanism (i.e., only hydrophobic interaction mechanism). The apparent diffusion coefficients of NOM, as determined from NOM diffusion experiments using a diffusion cell equipped with a regenerated cellulose membrane, were much lower than those calculated by the Stokes-Einstein relation. The diffusion coefficient of NOM is expected to be used to predict and explain NOM transport behaviors in tight-UF membranes.     

微生物转化法合成L-酪氨酸

以对羟基苯甲醛、海因、氢氧化钠为原料 ,化学合成底物对羟基苯丙酮酸。采用来自大肠杆菌的天冬氨酸转氨酶对对羟基苯丙酮酸进行生物转化 ,并对转化条件进行了初步的研究 ,最终得到L-酪氨酸 ,转化率 75 %。     

Coupling of dry matter and nitrogen accumulation in ryegrass

The logistic model has proven very useful in relating dry matter production of warm season perennial forage grasses to applied nitrogen. A recent extension of the model coupled dry matter and plant N accumulation through a common response coefficient c. The objective of this analysis was to apply the extended logistic model to cool season Gulf annual ryegrass (Lolium multiflorum Lam.) and to establish a common response coefficient c between accumulation of dry matter and plant N. Analysis of variance established the validity of this hypothesis. The model accurately described response of dry matter, plant N removal, and plant N concentration to applied N, with an overall correlation coefficient of 0.9954. Furthermore, the model closely described the relationship between yield and plant N removal, as well as between plant N concentration and plant N removal. The logistic equation is well-behaved and simple to use on a pocket calculator. It can be used to estimate yields and plant N removal in evaluation of agricultural production and environmental quality.     

基于模糊物元法的黑龙江干流区生态健康评价

针对受堤防建设影响的黑龙江干流地区,基于压力-状态-响应(PSR)模型构建了流域生态健康评价体系;利用层次分析法和模糊物元理论建立了流域生态健康模糊物元评价模型,并应用到黑龙江干流行政区的生态健康评价中。结果表明,漠河县、黑河市区、同江市区和抚远县干扰前的生态健康评价值为0.679 3,0.728 3,0.731 4,0.755 8,干扰后为0.602 3,0.580 5,0.611 7,0.722 6;漠河县生态健康等级保持"亚健康",黑河市区和同江市区的生态健康等级降为"亚健康",抚远县生态健康等级保持"健康"。同时,4个评价单元对应的生态受损程度分别为11.34%,20.29%,16.37%和4.39%。此外,根据评价指标体系综合分析了4个县市存在的生态健康问题,提出了4县市生态环境保护应采取的措施。     

Biodesulfurization of dibenzothiophene sulfone by Arthrobacter sp. and studies with oxidized Illinois No. 6 coal

A bacterium identified as Arthrobacter sp. was grown on dibenzothiophene (DBT) sulfone as a sole source of sulfur, producing sulfite and sulfate. Sulfur in DBT sulfone (1.0 mM) was nearly quantitatively converted to sulfate by the organism. The organism could also use DBT sulfone as a sole source of carbon and energy. There was evidence for transient accumulation of benzoic acid in the culture medium after growth of the cells slowed. The DBT sulfoxide analogue 9-fluorenone was converted by resting cells to a product identified as 1,10-dihydroxy-1,10-dihydrofluoren-9-one, suggesting that DBT sulfone may be metabolized via an angular hydroxylation resulting in carbon- sulfur bond cleavage. This strain of Arthrobacter showed no ability to desulfurize oxidized Illinois No. 6 coal.     

微生物絮凝剂的研究及发展前景

对微生物絮凝剂的现状与发展趋势做了全面综述,包括合成絮凝剂的微生物种类,微生物絮凝剂的絮凝机理及其影响因素,微生物絮凝剂的提取方法等,并阐述了微生物絮凝剂的性质、特点等.     

Determination of residual organic matter in extracted oil sands using a low temperature ashing method

The application of a low temperature ashing method for estimating total residual organic matter (toluene insolubles) in oil sands is described. A linear correlation exists between organic carbon content and loss on ignition at 400 ± 10 °C of solvent extracted oil sands. The ratio between total organic carbon and the weight loss on ignition (CT/LOl) owing to the removal of residual organic matter is much lower than that obtained for toluene soluble bitumen fractions, indicating very different chemical composition for the residual organic matter. The measured carbon content of the residual organic matter in oil sands suggests that this material could be a mixture of various fractions contained in resins, asphaltenes, asphaltic acids and humic acids.     

Chemical control of colloidal fouling of reverse osmosis systems

Fouling of membranes by colloidal organic and inorganic particles continues to be documented as the most common and challenging obstacle in attaining stable continuous operation of reverse osmosis (RO) and ultrafiltration (UF) systems. Much current research is being conducted on physical parameters to mitigate such fouling. The focus has been on membrane synthesis and element design; microfiltration and ultrafiltration pretreatment; electromagnetic devices; correlation with physical factors such as Silt Density Index, zeta potential and critical flux; technique of direct observation of fouling process through a membrane; and classification of macromolecular organics for correlation with fouling characteristics. We report initial successes with chemical control of colloidal fouling. Through screening with a large number of observable coagulations of natural colloids, we have developed a group of proprietary anticoagulants and dispersants that would, at less than 10 ppm dosage to the RO feedwater, control various classes of colloidal foulants. Case studies of the control of humic matter, elemental sulfur and colloidal silicate in problematic RO systems that became stabilized are briefly presented. We conclude that a great need and potential exists in economically controlling the myriads of fouling interactions of colloidal particles during concentration within the brine channels of RO membrane elements. Low dosages of antifoulants can in many cases obviate the need for installation and maintenance of pretreatment unit or operations designed to remove such colloidal foulants from the process stream.     

污泥调理剂

综述了污泥调理中常用的化学调理剂及其各自的优缺点,着重介绍了因具有安全、无毒、可生物降解、无二次污染等独特的性质而倍受人们的关注的生物絮凝剂。