膜生物反应器活性污泥酶活与磷脂脂肪酸分析

分析了不同污染负荷下膜生物反应器的运行效率,并运用酶活表征污泥活性,用磷脂脂肪酸(PLFAs)分析微生物种群结构及其分布特征.结果表明,膜生物反应器对COD,TP,TN,NH4+-N 保持着高而稳定的去除率,不同有机负荷下去除率差异不大(P>0.05);磷酸酶活性在低污染负荷下最高,脱氢酶、β-糖苷酶在中低污染负荷时的活性比高污染负荷时高,脲酶及蛋白酶活性随负荷增加而升高;活性污泥PLFAs 组成以单不饱和脂肪酸、饱和脂肪酸和支链脂肪酸为主,而多不饱和脂肪酸与环丙烷脂肪酸含量较少,特征脂肪酸的比值表明在反应器中好氧细菌占绝对优势;微生物的群落结构分析显示,活性污泥中好氧原核微生物为优势类群,其次是革兰氏阳性细菌及其他厌氧细菌,而真核微生物所占比例最低.     

Marine-derived nutrients, bioturbation, and ecosystem metabolism: reconsidering the role of salmon in streams

In coastal areas of the North Pacific Ocean, annual returns of spawning salmon provide a substantial influx of nutrients and organic matter to streams and are generally believed to enhance the productivity of recipient ecosystems. Loss of this subsidy from areas with diminished salmon runs has been hypothesized to limit ecosystem productivity in juvenile salmon rearing habitats (lakes and streams), thereby reinforcing population declines. Using five to seven years of data from an Alaskan stream supporting moderate salmon densities, we show that salmon predictably increased stream water nutrient concentrations, which were on average 190% (nitrogen) and 390% (phosphorus) pre-salmon values, and that primary producers incorporated some of these nutrients into tissues. However, benthic algal biomass declined by an order of magnitude despite increased nutrients. We also measured changes in stream ecosystem metabolic properties, including gross primary productivity (GPP) and ecosystem respiration (ER), from three salmon streams by analyzing diel measurements of oxygen concentrations and stable isotopic ratios (delta O-O2) within a Bayesian statistical model of oxygen dynamics. Our results do not support a shift toward higher primary productivity with the return of salmon, as is expected from a nutrient fertilization mechanism. Rather, net ecosystem metabolism switched from approximately net autotrophic (GPP > or = ER) to a strongly net heterotrophic state (GPP < ER) in response to bioturbation of benthic habitats by salmon. Following the seasonal arrival of salmon, GPP declined to <12% of pre-salmon rates, while ER increased by over threefold. Metabolism by live salmon could not account for the observed increase in ER early in the salmon run, suggesting salmon nutrients and disturbance enhanced in situ heterotrophic respiration. Salmon also changed the physical properties of the stream, increasing air-water gas exchange by nearly 10-fold during peak spawning. We suggest that management efforts to restore salmon ecosystems should consider effects on ecosystem metabolic properties and how salmon disturbance affects the incorporation of marine-derived nutrients into food webs.     

Social Contract and Deterring Famine: First Thoughts

The links between certain kinds of political systems and protection against famine are investigated in this paper. The starting-point is a critique of Amartya Sen's observation that famines are unknown in countries with a free press and competitive elections. This holds true only in India because of a unique political history in which freedom from famine became a right, upon which political legitimacy was founded: an anti-famine 'social contract'.
The rise and decline of anti-famine systems in Africa is charted. Major reasons for decay include neo-liberalism and the international humanitarian system, both of which undermine relationships of domestic political accountability that underpin effective famine prevention. A number of politically regressive tendencies in 'actually existing humanitarianism' are identified that work against any nascent anti-famine social contracts in Africa. This is possible because famine prevention has not been established as a right in Africa.     

北京雾霾天气期间气溶胶光学特性

为了解北京地区雾霾天气条件下大气气溶胶的光学特性,利用2002～2008年AERONET资料分析了雾霾天气期间气溶胶光学厚度、Angstrom波长指数、粒子尺度谱分布和单次散射反照率等气溶胶光学特性参数.结果表明,北京地区雾霾天气期间气溶胶光学厚度表现出较高值,且随波长增大而减小,440 nm时平均气溶胶光学厚度达到1.34.Angstrom波长指数在雾霾天气时也表现出较高值,平均值达到1.11;其中高于0.9的波长指数出现频率达到94%,说明北京雾霾天气期间气溶胶粒子主要以细粒子为主.气溶胶体积尺度谱分布表现出双峰型结构,细模态的平均峰值半径随光学厚度增大而增大,而粗模态的平均峰值半径却随光学厚度增大表现出减小趋势;气溶胶粒子尺度谱中的主模态峰与光学厚度有关.雾霾天气期间平均单次散射反照率达到0.89,且随光学厚度增大表现出依次增大趋势,但对波长变化表现不敏感.     

Parent cultural control through organizational acculturation: HCN employees learning new work values in foreign business subsidiaries

Local employees in foreign business subsidiaries could learn new work values from the parent organizational culture through a process of organizational acculturation. As this is a new concept in academic research, it is important to explore organizational acculturation and its ramifications, especially since it may be used as a strategy of cultural control applied by the parent organization. Following a discussion of the theoretical foundation of this concept, the consequences of organizational acculturation are exemplified by an investigation of middle managers in Singapore. The study was undertaken in two stages. The first stage included a comparison of work values of Singaporean managers, employed by Swedish companies in Singapore, and those of a control group of Singaporean managers, not employed by Swedish companies. In the second stage, work values of managers in Singapore and Sweden were compared. Our results imply that some Swedish work values had been adopted, suggesting that the local managers had experienced organizational acculturation. Practical implications and possible further research are discussed.     

Land-Use Change and Carbon Flux Between 1970s and 1990s in Central Highlands of Chiapas, Mexico

6 tons C were released to the atmosphere during the period of time covered by our study, equal to approximately 34% of the 1975 vegetation C pool. The Chiapas highlands, while comprising just 0.3% of Mexico's surface area, contributed 3% of the net national C emissions.     

Using simulated rainfall to evaluate field and indoor surface runoff phosphorus relationships

While numerous studies have evaluated the efficacy of outdoor rainfall simulations to predict P concentrations in surface runoff, few studies have linked indoor rainfall simulations to P concentrations in surface runoff from agricultural fields. The objective of this study was to evaluate the capacity of indoor rainfall simulation to predict total dissolved P concentrations [TP(<0.45)] in field runoff for four dominant agricultural soils in South Dakota. Surface runoff from 10 residue-free field plots (2 m wide by 2 m long, 2-3% slope) and packed soil boxes (1 m long by 20 cm wide by 7.5 cm high, 2-3% slope) was compared. Surface runoff was generated via rainfall simulation at an intensity of 65 mm h(-1) and was collected for 30 min. Packed boxes produced approximately 24% more runoff (range = 2.8-3.4 cm) than field plots (range = 2.3-2.7 cm) among all soils. No statistical differences in either TP(<0.45) concentration or TP(<0.45) loss was observed in runoff from packed boxes and field plots among soil series (0.17 < P < 0.83). Three of four soils showed significantly more total P lost from packed boxes than field plots. The TP(<0.45) concentration in surface runoff from field plots can be predicted from TP(<0.45) concentration in surface runoff from the packed boxes (0.68 < r(2) < 0.94). A single relationship was derived to predict field TP(<0.45) concentration in surface runoff using surface runoff TP(<0.45) concentration from packed boxes. Evidence is provided that indoor runoff can adequately predict TP(<0.45) concentration in field surface runoff for select soils.     

Analysis of Organophosphorus Pesticides in Whole Milk by Solid Phase Microextraction Gas Chromatography Method

Solid phase microextraction (SPME) was used for the extraction of residual coumaphos and dichlorvos in whole milk. The residues were analyzed by capillary gas chromatography equipped with nitrogen phosphorus detector (GC-NPD). A manual SPME holder with a 100-μm polyacrylate fiber was used. The optimized conditions for extraction by SPME method were: sample agitation, absorption temperature of 30°C, absorption time of 40 min, desorption time of 10 min, and sample volume was 16.0 mL in the vial. Under these conditions, the calibration graphs were linear in the range of 0.17 μgL^?1 to 1.75 μgL^?1 for coumaphos and 0.69 μgL^?1 to 6.90 μgL^?1 for dichlorvos. Precision was good with RSD values of 13% for coumaphos and 14% for dichlorvos. The detection limits (LOD) were 0.060 μgL^?1 for dichlorvos and 0.052 for coumaphos. The quantification limits (LOQ) were 0.086 μgL^?1 for dichlorvos and 0.066 μgL^?1 for coumaphos. The results obtained in this study suggest that SPME is a suitable technique for residual pesticide analysis of milk. The data demonstrate that particular OP pesticides used in dairy farming in the region of Minas Gerais were found to contaminate cow whole milk, and the residues are not removed by treating the milk by boiling.