Contamination of Clams with Human Norovirus and a Novel Hepatitis A Virus in Cameroon

Food and Environmental Virology - Shellfish constitute an important protein source but may be contaminated by viruses from various origins. A study performed on clams collected in Cameroon showed a...     

Are politicians office or policy motivated? The case of U.S. governors' environmental policies

Are elected politicians primarily motivated by holding office, thus choosing environmental policies accordingly? Or are they motivated by the chance to implement their preferred environmental policies? Do governors have character, in the sense that they promise and implement environmental policies consistent with their own preferences? To answer these questions, we study the differences in environmental spending across both re-electable and lame duck governors from the two main political parties. In our empirical analysis, we make use of parametric and non-parametric regression-discontinuity approaches. While re-electable governors do not set significantly different policies, lame duck governors do. We argue that in the area of environmental policy governors appear to be primarily office motivated and lack character.     

Biological treatment process of air loaded with an ammonia and hydrogen sulfide mixture

The physico-chemical characteristics of granulated sludge lead us to develop its use as a packing material in air biofiltration. Then, the aim of this study is to investigate the potential of unit systems packed with this support in terms of ammonia and hydrogen sulfide emissions treatment. Two laboratory scale pilot biofilters were used. A volumetric load of 680 g H2S m(-3) empty bed day(-1) and 85 g NH3 m(-3) empty bed day(-1) was applied for eight weeks to a unit called BGSn (column packed with granulated sludge and mainly supplied with hydrogen sulfide); a volumetric load of 170 g H2S m(-3) empty bed day(-1) and 340 g NH3 m(-3) empty bed day(-1) was applied for eight weeks to the other called BGNs (column packed with granulated sludge and mainly supplied with ammonia). Ammonia and hydrogen sulfide elimination occur in the biofilters simultaneously. The hydrogen sulphide and ammonia removal efficiencies reached are very high: 100% and 80% for BGSn; 100% and 80% for BGNs respectively. Hydrogen sulfide is oxidized into sulphate and sulfur. The ammonia oxidation products are nitrite and nitrate. The nitrogen error mass balance is high for BGSn (60%) and BGNs (36%). This result could be explained by the denitrification process which would have occurred in anaerobic zones. High percentages of ammonia or hydrogen sulfide are oxidized on the first half of the column. The oxidation of high amounts of hydrogen sulfide would involve some environmental stress on nitrifying bacterial growth and activity.     

Automatic continuous river monitoring of nitrate using a novel ion-selective electrode

On-site continuous measurement of nitrate in the River Taw situated in Devon (UK) was performed automatically for two months using a recently developed ion-selective electrode (ISE). A non-submersible electrode support system was developed and a field instrument was constructed comprising the nitrate-ISEs, a reference electrode and a temperature probe connected through a pre-amplifier to a data-logger and battery supply. The nitrate-ISE was constructed using a commercially available electrode body with a membrane incorporated into the tip. This rubbery membrane contained the sensor molecule (N,N,N-triallylleucine betaine chloride, 6.5% m/m) covalently bound to polystyrene-block-polybutadiene-block-polystyrene, SBS, (43.5% m/m), with 2-nitrophenyloctyl ether (2-NPOE) as mediator (40% m/m). The Nernstian slope was -59.1 mV per decade over a linear range of 1400-0.07 mg L(-1) nitrate-N. The limit of detection was 0.007 mg L(-1) nitrate-N with a selectivity coefficient for nitrate against chloride (k(pot)NO3-, Cl-) of 3.4 x 10(-3). The speed of response was less than a minute over the linear Nernstian range. The lifetime in the laboratory exceeded 5 months with no potentiometric drift over the linear Nernstian range. A temperature correction algorithm was also used to accomodate the temperature changes encountered in the river. The river nitrate results obtained with the ISEs at hourly intervals compared very favourably (R2 = 0.9) with those obtained with laboratory automated chemical determinations made on contemporaneous river samples over a concentration range 0.55-2.00 mg L(-1) nitrate-N. The ISEs did not require re-calibration and no deterioration in performance or fouling of the membrane surface was observed during 40 days.     

Metal concentrations in deciduous tree leaves from urban areas in Poland

Accumulation of metals in deciduous tree foliage fromurban areas in western-south Poland was monitored duringthe vegetation season of 2000 year. Concentrations of Al,Ba, Ca, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sr, Ti and Znwere measured in birch, willow, linden and maple leavesusing the ICP-AES method. Seasonal variations of metalconcentrations and their relations with sampling sitewere investigated. The most dynamic accumulation of Al,Cd, Cr, Ni and Pb was observed for examined species. Thehighest differences in element concentrations forinvestigated sites were found for Ba, Cd, Mn and Ni.Interelement correlations were investigated. In allfoliar samples synergistic relationships between Al–Crand Ca-Sr were found. Statistically significant negativecorrelations were observed only for Cd and Ti in birch leaves.     

运用能见度因子对大气稳定度参数的计算及和国标分类法的对比

分析了国际分类法的不足，引入能见度因子对大气稳定度参数进行计算，分别利用两种分类计算方法计算上海市市某气象站１９９６年逐时气象资料，再对比分析不同分类结果后，得出能见度因子对大气稳定度数的计算比国际分类法更接近实际情况。     

碳纳米管界面改性超滤膜的抗污机理解析

以碳纳米管(CNT)为核心改性材料,采用喷涂法对聚醚砜(PES)超滤膜进行界面改性,研究改性膜的抗污染性能.结果表明:改性膜经聚乙烯醇交联稳定后,呈现微弱的通透性降低和明显的亲水性提升,CNT交织网状层提高了界面粗糙度;在牛血清白蛋白(BSA)污染试验中,CNT-10改性膜的抗污性能最好,在20mg/L BSA试验后,...