几种牺牲阳极在干湿交替条件下的自放电行为比较

模拟海水与空气的干湿交替条件,对四种海船常用牺牲阳极的自放电行为进行了研究。通过测定工作电位、发生电流、溶解性能、溶解产物成分,分析了四种牺牲阳极在经历不同间浸工作周期后的电化学性能,特别是再活化性能。结果表明:在干湿交替条件下,Zn-Al-Cd阳极的电化学性能降低幅度最大,Al-Zn-In-Cd阳极次之,它们均不适合在此环境中使用;Al-Zn-In-Mg-Ti的电化学性能比前两者好,Al-Zn-In-Mg-Ga-Mn则最适合作为干湿交替环境中的牺牲阳极。     

非潮汐淹水对白骨壤膜脂过氧化系统的影响

通过室内模拟非潮汐淹水,探索不同淹水水位条件下,红树植物白骨壤(A.marina(Forsk.)Vierh).超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、丙二醛(MDA)随时间的变化情况。结果表明,经历第二个淹水周期后,较第一个周期各梯度,白骨壤超氧化物歧化酶活性(SOD)从高到低排序不变,过氧化氢酶活性(CAT)、丙二醛的量(MDA)也表现出相同的规律。本研究结论为红树植物在人工非潮汐生境下,红树林造林的关键技术之一——淹水水位的控制提供了数据参考。     

非职业性一氧化碳中毒事件成因分析

通过对燃煤量的调查结果和呼和浩特CO浓度值监测结果分析了CO排放源的分布特征和CO浓度的变化特征,得出高燃煤地区和采暖期CO浓度值较高但低于标准值。对CO中毒事件案例与气象条件关系进行了分析得出逆温、高湿、小风和低气压时不利于一氧化碳浓度扩散,容易引起一氧化碳中毒事件的发生。     

Does safety climate moderate the influence of staffing adequacy and work conditions on nurse injuries?

PROBLEM: Hospital nurses have one of the highest work-related injury rates in the United States. Yet, approaches to improving employee safety have generally focused on attempts to modify individual behavior through enforced compliance with safety rules and mandatory participation in safety training. We examined a theoretical model that investigated the impact on nurse injuries (back injuries and needlesticks) of critical structural variables (staffing adequacy, work engagement, and work conditions) and further tested whether safety climate moderated these effects. METHOD: A longitudinal, non-experimental, organizational study, conducted in 281 medical-surgical units in 143 general acute care hospitals in the United States. RESULTS: Work engagement and work conditions were positively related to safety climate, but not directly to nurse back injuries or needlesticks. Safety climate moderated the relationship between work engagement and needlesticks, while safety climate moderated the effect of work conditions on both needlesticks and back injuries, although in unexpected ways. DISCUSSION AND IMPACT ON INDUSTRY: Our findings suggest that positive work engagement and work conditions contribute to enhanced safety climate and can reduce nurse injuries.     

Emissions of SO2, NO and N2O in a circulating fluidized bed combustor during co-firing coal and biomass

This paper presents the experimental investigations of the emissions of SO2, NO and N2O in a bench scale circulating fluidized bed combustor for coal combustion and co-firing coal and biomass. The thermal capacity of the combustor is 30 kW. The setup is electrically heated during startup. The influence of the excess air, the degree of the air staging, the biomass share and the feeding position of the fuels on the emissions of SO2, NO and N2O were studied. The results showed that an increase in the biomass shares resulted in an increase of the CO concentration in the flue gas, probably due to the high volatile content of the biomass. In co-firing, the emission of SO2 increased with increasing biomass share slightly, however, non-linear increase relationship between SO2 emission and fuel sulfur content was observed. Air staging significantly decreased the NO emission without raising the SO2 level. Although the change of the fuel feeding position from riser to downer resulted in a decrease in the NO emission level, no obvious change was observed for the SO2 level. Taking the coal feeding position R as a reference, the relative NO emission could significantly decrease during co-firing coal and biomass when feeding fuel at position D and keeping the first stage stoichiometry greater than 0.95. The possible mechanisms of the sulfur and nitrogen chemistry at these conditions were discussed and the ways of simultaneous reduction of SO2, NO and N2O were proposed.     

Characterizing ionic species in PM2:5 and PM10 in four Pearl River Delta cities, South China

PM_(2.5)and PM_(10)samples were collected at four major cities in the Pearl River Delta(PRD),South China,during winter and summer in 2002.Six water-soluble ions,Na~ ,NH_4~ ,K~ ,Cl~-,NO_3~- and SO_4~(2-)were measured using ion chromatography.On average,ionic species accounted for 53.3% and 40.5% for PM_(2.5)and PM_(10),respectively in winter and 39.4% and 35.2%,respectively in summer. Secondary ions such as sulfate,nitrate and ammonium accounted for the major part of the total ionic species.Sulfate was the most abundant species followed by nitrate.Overall,a regional pollution tendency was shown that there were higher concentrations of sulfate, nitrate and ammonium in Guangzhou City than those in the other PRD cities.Significant seasonal variations were also observed with higher levels of species in winter but lower in summer.The Asian monsoon system was favorable for removal and diffusion of air pollutants in PRD in summer while highly loading of local industrial emissions tended to deteriorate the air quality as well.NO_3~-/SO_4~(2-) ratio indicated that mobile sources have considerably contribution to the urban aerosol,and stationary sources should not be neglected. Besides the primary emissions,complex atmospheric reactions under favorable weather conditions should be paid more attention for the control of primary emission in the PRD region.     

Nitrogen cycling of atmosphere-plant-soil system in the typical Calamagrostis angustifolia wetland in the Sanjiang Plain, Northeast China

The nitrogen (N) distribution and cycling of atmosphere-plant-soil system in the typical meadow Calamagrostis angustifolia wetland (TMCW) and marsh meadow Calamagrostis angustifolia wetland (MMCW) in the Sanjiang plain were studied by a compartment model. The results showed that the N wet deposition amount was 0.757 gN/(m2·a), and total inorganic N (TIN) was the main body (0.640 gN/(m2·a)). The ammonia volatilization amounts of TMCW and MMCW soils in growing season were 0.635 and 0.687 gN/m2, and the denitrification gaseous lost amounts were 0.617 and 0.405 gN/m2, respectively. In plant subsystem, the N was mainly stored in root and litter. Soil organic N was the main N storage of the two plant-soil systems and the proportions of it were 93.98% and 92.16%, respectively. The calculation results of N turnovers among compartments of TMCW and MMCW showed that the uptake amounts of root were 23.02 and 28.18 gN/(m2·a) and the values of aboveground were 11.31 and 6.08 gN/(m2·a), the re-translocation amounts from aboveground to root were 5.96 and 2.70 gN/(m2·a), the translocation amounts from aboveground living body to litter were 5.35 and 3.38 gN/(m2·a), the translocation amounts from litter to soil were larger than 1.55 and 3.01 gN/(m2·a), the translocation amounts from root to soil were 14.90 and 13.17 gN/(m2·a), and the soil (0-15cm) N net mineralization amounts were 1.94 and 0.55 gN/(m2·a), respectively. The study of N balance indicated that the two plant-soil systems might be situated in the status of lacking N, and the status might induce the degradation of C. angustifolia wetland.     

枯草芽孢杆菌对微污染水体的净化作用

采用投加枯草芽孢杆菌的水质净化方法,系统考察了在典型南方夏季气温下,封闭的模拟微污染水枯草芽孢杆菌净化体系中,投菌浓度、主要环境条件（pH和溶解氧）及其冲击对净化效果的影响.结果表明,枯草芽孢杆菌的最佳投菌浓度为3.2×105cfu·mL-1,适宜的环境条件为：pH5～7,溶解氧4～6mg·L-1.投菌9d后,CODM...     

城镇污水处理排放标准改革的费效分析

从费用效果角度对提高城镇污水处理排放标准的科学性和可实施性进行探讨,利用污染源普查数据,通过城镇污水治理投资和运行函数的构建,计算不同处理规模和排放标准下的污水处理投资和运行费用,在全国层面上计算提高污水处理排放标准所需费用和污染物的减排效果.研究表明：污水处理厂的投资和运行费用的增加随着污水处理规模的增加而递减.以污...     

Effect of nutrient conditions on the toxicity of naphthalene to Chlorella pyrenoidosa

The toxicity of naphthalene to a freshwater microalga, Chlorella pyrenoidosa, and the subsequent recovery of algae from the damage were investigated under two nutrient conditions, either enriched with nitrogen (N) and phosphorus (P), or starved of N and P. Results showed that C. pyrenoidosa was more sensitive to naphthalene under N,P-enriched condition, and the inhibitory rate generally increased at first and then decreased gradually with the evaporation of naphthalene under both nutrient conditions. Enriched N, P reduced the inhibitory rate at initial naphthalene concentration of 5 and 10 mg/L, but enhanced it at 100 mg/L, at which more severe ultrastructure damages were found than those under N,P-starved condition. Observed damages included partly or totally disappearance of nucleolus, nuclear, and plasma membranes. According to the chlorophyll content and cell density measurements, C. pyrenoidosa could recover from naphthalene damage with initial concentrations 6 50 mg/L in 7 days under both nutrient conditions, while they could not recover if the initial concentration of naphthalene was at 100 mg/L. Under the N,P-starved condition, the inability of C. pyrenoidosa to recover from the naphthalene damage was consistent with the results of high inhibitory rate, low value of specific growth rate (SGR, 0.05 day??1), and the severe destruction of cell structure. However, under the N,P-enriched conditions, the observed lower inhibitory rate, higher value of SGR (0.55 day??1), and the intact cell structure of most cells suggested that algae could potentially recover from the naphthalene damage.