Statistical theory of the Marshall-Palmer distribution of raindrops

A statistical model is developed for the large-sample-averaged raindrop size spectrum. Under the condition that the “instant” spectrum can be fitted with a gamma distribution, n(D) = N₀D^μe^−λD, it is proven that the averaged spectrum approaches the Marshall-Palmer distribution, n(D) = N₀e^−λD, with the sample number increasing.     

An investigation of three-dimensional characteristics of flow regimes within the urban canyon

Canyon geometry is an important determinant characteristic airflow regimes observed within urban canyons. Three principal flow regimes are: “skimming” flow, “wake interference” flow and “isolated roughness” flow, following the nomenclature of Oke (1987, Boundary Layer Climates, 2nd edn, Methuen, London). The transition between flows is determined by canyon geometry and can be described in terms of threshold height/width (H/W) ratios for an arbitrary length/height (L/H) ratio.The determination of threshold H/W ratios has previously relied on repeated wind tunnel experiments or repeated runs of a numerical model, with canyon geometry altered until the observed flow regime changes. The present numerical investigation of typical three-dimensional flows within urban canyons identifies the key parameters which mark transition between flow regimes. On this basis it is possible to establish the geometric thresholds between regimes with analysis of a horizontal cross-section of a few simulated flows.     

The Hirudo medicinalis species complex

Recently, Hildebrandt and Lemke (Naturwissenschaften 98:995–1008, 2011) argued that the taxonomic status of the three European medicinal leeches, Hirudo medicinalis Linnaeus 1758, Hirudo verbana Carena 1820, and Hirudo orientalis Utevsky and Trontelj (Parasitol Res 98:61?66, 2005) is “questionable” since “all three species interbreed in the laboratory”. This statement is in conflict with data published by Elliott and Kutschera (Freshwater Reviews 4:21?41, 2011), indicating that these leeches, which are reciprocally copulating hermaphrodites, represent reproductively isolated biospecies. Here, I summarize evidence indicating that these three European taxa, plus the North African “dragon leech” (Hirudo troctina Johnson 1816), must be interpreted as a complex of closely related species, and that the economically most important taxon H. verbana is polymorphic.     

Optimising yield and resource utilisation of summer maize under the conditions of increasing density and reducing nitrogen fertilization

The inefficient use of resources always poses risks of maize (Zea mays L.) yield reduction in China. We performed this research to monitor the effects of increasing plant density and reducing nitrogen (N) rate on radiation-use efficiency (RUE), N efficiency traits, grain yield (GY) and their inter-relationships. Besides, whether GY and resource-use efficiency can both be maximized was examined. Hence, a 2-year field experiment was conducted using a widely grown variety “Denghai 618” in Shandong, China. Treatments contained two different plant densities [67,500 (D₁) and 97,500 (D₂) plant ha^?1] and three N levels [0 (N_?2), 180 (N_?1), 360 (N_ck) kg ha^?1], set D₁N_ck as control. Significant increases in grain yield, biomass, RUE, above-ground N uptake (AGN) and N efficiency were observed when density increased from D₁ to D₂. Declining N application was accompanied by reductions in yield, RUE and AGN especially under high density, yet an obvious improvement in N recovery efficiency (NRE), agronomic N efficiency and N partial factor productivity. The increased GY was positive related with population biomass (r = 0.895**), RUE (r = 0.769**) and AGN (r = 0.923**), whereas it has no significant correlation with N efficiency. In this study, D₂N_ck obtained 18.8, 17.9, 24.8 and 29.7% higher grain yield, RUE, AGN and NRE respectively, compared to control, optimizing both yield and the efficiencies of radiation and N use. Furthermore, higher yield and RUE with more desirable N efficiency may be possible via optimizing density and N rate combination.     

Nitrous oxide reductase gene (nosZ) and N2O reduction along the littoral gradient of a eutrophic freshwater lake

Lake littoral zones are characterized by heterogeneity in the biogeochemistry of nutrient elements. This study aimed to explore the relationship between the nitrous oxide reductase gene (nosZ)-encoding denitrifier community composition/abundance and N2O reduction. Five samples (deep sediment, near-transition sediment, transition site, near-transition land and land soil) were collected along a littoral gradient of eutrophic Baiyangdian Lake, North China. To investigate the relationship between the nosZ-encoding denitrifier community structure and N2O reduction, the nosZ-encoding denitrifier community composition/abundance, potential denitrification rate (DNR) and potential N2O production rate (pN2O) were investigated using molecular biological technologies and laboratory incubation experiments. The results showed that the average DNR of sediments was about 25 times higher than that of land soils, reaching 282.5 nmol N/(g dry weight (dw)·hr) and that the average pN2O of sediments was about 3.5 times higher than that of land soils, reaching 15.7 nmol N/(g dw·hr). In the land area, the nosZ gene abundance showed a negative correlation with the N2O/(N2O+N2) ratio, indicating that nosZ gene abundance dominated N2O reduction both in the surface soils of the land area and in the soil core of the transition site.Phylogenetic analysis showed that all the nosZ sequences recovered from sediment clustered closely with the isolates Azospirillum largimobile and Azospirillum irakense affiliated to Rhodospirillaceae in alpha-Proteobacteria, while about 92.3% (12/13) of the nosZ sequences recovered from land soil affiliated to Rhizobiaceae and Bradyrhizobiaceae in α-Proteobacteria. The community composition of nosZ gene-encoding denitrifiers appeared to be coupled with N2O reduction along the littoral gradient.     

Simulation based life cycle assessment of airborne emissions of biomass-based ethanol products from different feedstock planting areas in China

Oil shortage and environmental deterioration urge people to pay more and more attention to Biomass-based Fuel Ethanol (BFE), because it is renewable and apparently environmentally friendly. This paper aims to assess and compare the air emissions of three BEF products from different feedstock planting areas in China. For the purpose of a “cradle to grave” study of biomass-based ethanol fuel as a substitute transportation fuel, the authors chose “vehicle fueled by biomass-based E10 (a blend of 10% ethanol and 90% gasoline, v/v)” as the subject. Then, life cycle emission models of Wheat-based E10 from central China, Corn-based E10 from northeast China, and Cassava-based E10 from southwest China were set up based on surveys; life cycle emission functions of CO₂, CO, N₂O, NO_x, SO₂, CH₄, VOC, and PM₁₀ were constructed and value of each emission category was calculated based on Monte Carlo simulation of the life cycle emission models. The calculation results showed that compared with gasoline-fueled vehicles, biomass-based E10-fueled vehicles release less CO₂ and VOC in their lifecycles, but wheat-based E10-fueled and cassava-based E10-fueled ones have more emissions of CO, CH₄, N₂O, NO_x, SO₂, PM₁₀ and corn-based E10-fueled ones have more emissions of CH₄, N₂O, NO_x, SO₂, PM₁₀. Suggestions on reducing the emissions have been proposed for future actions.     

猪粪化肥配施对双季稻田CH4和N2O排放及其全球增温潜势的影响

以湖南典型红壤双季稻田系统为研究对象,采用静态箱-气相色谱法研究了水稻生长季基肥配施猪粪条件下CH4和N2O的排放特征,并估算了排放的CH4和N2O的全球增温潜势(GWP).结果表明,与施用化肥处理相比,猪粪化肥配施对稻田CH4和N2O排放的季节变化模式无明显影响,但影响其排放量大小.两个稻季,猪粪替代50%化学氮肥处理(1/2N+PM)CH4累积排放量较不施氮肥处理(0N)、50%化学氮肥处理(1/2N)、100%化学氮肥处理(N)分别提高54.83%、33.85%和43.30%(P<0.05);1/2N+PM处理N2O累积排放量较N处理显著降低67.50%,较0N处理、1/2N处理分别提高129.43%、119.23%(P<0.05).水稻生长季CH4是GWP的主要贡献者,占CH4和N2O综合GWP的99%以上.1/2N+PM处理的GWP显著高于其他处理(P<0.05),且1/2N+PM处理单位产量GWP最高,较N处理、1/2N处理、0N处理分别提高58.21%、26.82%、20.63%.因此,双季稻田猪粪替代部分化学氮肥较全部施用化学氮肥增加了双季稻田CH4和N2O排放的综合温室效应,其对温室气体排放的影响需在区域温室气体排放清单中加以考虑.     

Oxidation of organic substances in aqueous solutions over Ru catalysts by oxygen

The catalytic performance of supported Ru catalysts has been studied in the reactions of wet oxidation of acetonitrile, N,N-dimethyl formamide and carbamide at T=433–533 K and P=2.0–4.6 MPa, and wet oxidation of real sewage from an alcohol plant (so-called Luther water) at T=403–473 K and P=1.5–3.6 MPa. The Luther water contained a mixture of low-boiling (C₁–C₅) aldehydes and alcohols. The experiments were carried out in a perfectly mixed batch autoclave reactor. The conversion of alcohols and aldehydes contained in the Luther water and selectivity of the process towards CO₂ and water as well as the selectivity of the oxidation of acetonitrile, N,N-dimethyl formamide and carbamide towards CO₂, N₂ and water were determined at various temperatures and reaction times. Ru (4.8 wt.%)/graphite-like carbon was effective in the oxidation of Luther water (ΔTOC=97.5% at T=423 K for 1 h), carbamide (X_CO(NH2)2=100%, S_{CO(NH2)2→CO2}=100%, S_{CO(NH2)2→N2}=71% at 473 K, 2 h) and acetonitrile (X_CH3CN=100%, S_CH3CN→CO2=100%, S_CH3CN→N2=75% at 493 K, 1 h). Ru/active carbon/γ-Al₂O₃ was effective in the oxidation of N,N-dimethyl formamide (X_HCON(CH3)2=100%, S_{HCON(CH3)2→CO2}=61%, S_{HCON(CH3)2→N2}=100% at 493 K).     

N,N’-二(2-羟丙基)哌嗪-H2SO4水溶液吸收SO2动力学

在鼓泡式反应器中,以N,N’-二(2-羟丙基)哌嗪(HPP)-硫酸水溶液为吸收剂,利用初始速率法探讨了SO2吸收反应动力学.结果表明:HPP-H2SO4水溶液吸收SO2为快速反应;吸收速率NA随着SO2进口体积浓度yA和吸收剂浓度CN的增大而增大,随着吸收温度T的升高而降低;吸收速率对CN是0.5级反应,对yA为0.85级反应.同时,建立了HPP-H2 SO4水溶液吸收SO2的吸收速率NA与CN、yA及T之间的经验关系式,发现该经验关系式的预测值与实验值符合较好,可用于工程设计计算.     

生物炭和有机肥对菜地土壤N2O排放及硝化、反硝化微生物功能基因丰度的影响

通过室内培养试验和实时荧光定量PCR技术,研究了田间施用生物炭和有机肥对菜地土壤氧化亚氮(N_2O)排放、氨单加氧酶(amo A)和亚硝酸盐还原酶(nir S、nir K)、氧化亚氮还原酶(nos Z)基因丰度的影响,并探讨功能基因丰度对N_2O排放的影响.试验设置5个处理:CK(对照)、N(尿素)、N+BC(尿素和生物炭)、N+M(尿素和有机肥)和N+BC+M(尿素、生物炭和有机肥).结果表明,与CK处理相比,各施肥处理均降低了土壤氨氧化细菌(AOB)和氨氧化古菌(AOA)丰度,增加了nir K、nir S和nos Z基因丰度,并提高了培养期间N_2O累积排放量.与N处理相比,N+BC处理的土壤p H值提高了11.1%,并增加了AOB、AOA、nir S、nir K和nos Z基因丰度,增幅分别为105.8%、57.3%、22.0%、176.2%和204.9%,同时显著降低了培养期间N_2O累积排放量,降幅为58.1%;N+M处理增加了nir K和nir S基因丰度,增幅分别为58.8%和7.1%,对N_2O排放的影响不显著;N+BC+M处理增加了AOB、nir K、nir S和nos Z基因丰度,增幅分别为30.7%、68.7%、6.5%和84.5%,降低了N_2O累积排放量,降幅为14.4%.生物炭通过增加amo A、nir S和nir K基因丰度间接增加N_2O排放,同时通过增加nos Z基因丰度促进N_2O还原,综合效应表现为降低了菜地土壤N_2O排放.因此,通过施用生物炭改善土壤性质,增加功能基因丰度,降低土壤N_2O排放,是一种较好的N_2O减排措施.施用有机肥可以增加反硝化作用功能基因丰度,但对N_2O减排效果不显著.     

农田土壤施用系列新型氮肥后气态氮(NH3和N2O)减排效果比较:以夏玉米季为例

为了解不同品种新型氮肥相对常规施肥其氨(NH3)和氧化亚氮(N_2O)的减排效果,本文通过田间原位试验同步研究了夏玉米生长季氮肥施用后的农田NH_3挥发和N_2O排放及其主要驱动因子.以常规施肥(复合肥+尿素,CK)为对照,设置了5个肥料处理,分别为脲铵氮肥(UA)、稳定性复合肥料(UHD)、硫包衣氮肥(SCU)、脲甲醛复合肥(UF)和有机肥(OF),施氮量(以N计)均为300 kg·hm~(-2).相关分析结果表明,氨挥发和N_2O排放受环境因子影响,均与土壤WFPS呈显著负相关(P0.05),N_2O排放还与土壤硝态氮呈极显著正相关(P0.01).进一步回归分析表明,N_2O排放(F_(N_2O))主要取决于土壤硝态氮(x)含量的变化,而氨挥发(F_(NH_3))主要取决于土壤铵态氮(x)含量的变化.与CK相比,除了UA,其它肥料处理都降低了土壤的氨挥发,尤其是UF和OF处理减少了37%~43%.但对于N_2O排放,所有处理与CK皆无显著差异.进一步计算每种处理氨挥发和N_2O的气态氮损失总量,与CK相比,UHD、SCU、UF和OF分别减排了9%、5%、30%和23%,而UA增加了3%.     

Attractants from Bartlett pear for codling moth, Cydia pomonella (L.), larvae

The alkyl ethyl and methyl esters of (2E,4Z)-2,4-decadienoic acid found in head-space samples of ripe Bartlett pear (Pyrus communis L.) stimulated a response from neonate larvae of the codling moth (CM), Cydia pomonella (L.), in both static-air Petri-plate and in upwind Y-tube and straight-tube olfactometer bioassays. In comparison with the known CM neonate attractant, (E,E)-!-farnesene, ethyl (2E,4Z)-2,4-decadienoate was attractive at 10-fold and 1,000-fold lower threshold dosages in the Petri-plate and in the Y-tube bioassays, respectively. Methyl (2E,4Z)-2,4-decadienoate was attractive to CM neonates in these bioassays at much higher doses than ethyl (2E,4Z)-2,4-decadienoate. Other principal head-space volatiles from ripe pear fruit and pear leaves, including butyl acetate, hexyl acetate, (Z)-3-hexenyl acetate, and (E)-#-ocimene, were not attractive to CM neonates. The potential uses of these pear kairomones for monitoring and control of CM in walnuts and apple are discussed.     

Sex pheromone chemistry and field trapping studies of the elm spanworm Ennomos subsignaria (Hübner) (Lepidoptera:Geometridae)

The elm spanworm, Ennomos subsignaria (Hübner), occurs throughout Canada and the eastern United States and can be a destructive forest pest on a wide range of deciduous trees. Gas chromatography/mass spectrometry (GC/MS) and coupled gas chromatographic–electroantennographic detection (GC/EAD) analysis of pheromone gland extracts, in combination with chemical synthesis and field trapping studies have identified (2S, 3R)-2-((Z)-oct-2′-enyl)-3-nonyl oxirane (hereafter Z6-9S, 10R-epoxy-19:H) as the female-produced sex pheromone. Significantly more male moths were captured between 1–100 μg loadings of this compound on red rubber septa in sticky traps compared to blank (unbaited) traps; catches then declined at higher dosages (500–1000 μg). The other isomeric enantiomer, (2R, 3S)-2-[(Z)-oct-2′-enyl]-3-nonyl oxirane (Z6-9R, 10S-epoxy-19:H), at a 10-μg dosage did not elicit trap capture. The likely precursor to the active epoxide, (Z, Z)-6, 9-nonadecadiene ((Z, Z)-6, 9-19:H), identified in virgin female sex pheromone glands, did not elicit trap capture either, and inhibited trap capture when combined with the active epoxide. Racemic 2-((Z)-oct-2′-enyl)-3-nonyl oxirane showed no significant difference in trap capture compared with Z6-9S, 10R-epoxy-19:H, indicating that the opposite enantiomer was not antagonistic. The addition of the EAD-active diene epoxide enantiomers (2S, 3R)-2-[(Z, Z)-octa-2′, 5′-dienyl]-3-nonyl oxirane or (2R, 3S)-2-[(Z, Z)-octa-2′, 5′-dienyl]-3-nonyl oxirane in admixture with Z6-9S, 10R-epoxy-19:H (at 10% of the latter) did not enhance or decrease trap capture compared to Z6-9S, 10R-epoxy-19:H oxirane alone, so they are not likely pheromone components. This pheromone, impregnated in rubber septa at less than 100-μg dosage, can now be used as a trap bait to develop detection and monitoring strategies for this insect.     

Ecological modernisation: new perspectives

“Ecological modernisation” – understood as systematic eco-innovation and its diffusion – has by far the largest potential to achieve environmental improvements. In general, the market logic of modernisation and competition for innovation combined with the market potential of global environmental needs serve as important driving forces behind “ecological modernisation”. In recent times, however, additional factors like rising energy prices or fears from climate change have favoured the rise of this innovation-based approach to environmental policy. The article deals with two special driving forces: first, there is growing evidence for the importance of “smart” environmental regulation. Secondly, the increasingly complex actor constellation of global environmental governance leads to mounting business risks for polluters and thereby exerts pressure for eco-innovation.Despite these favourable framework conditions, the strategy of “ecological modernisation” nonetheless faces a number of inherent limitations. These include the unavailability of marketable technological solutions for relevant environmental problems like the loss of species, the rebound effect neutralising the incremental environmental improvements through economic growth (the dilemma of the “N-curve”) as well as resistance by “modernisation losers”. Against this background, structural solutions seem indispensable. Here, eco-innovations should be supported by transition management or ecological structural policy.     

Methane,nitrous oxide and ammonia emissions during storage and after application of dairy cattle slurry and influence of slurry treatment

Slurries are a significant source of CH₄, NH₃ and N₂O emissions to the atmosphere. The research project aimed at quantifying CH₄, NH₃ and N₂O emissions from liquid manure stores and after manure application under field conditions. The influence of the manure treatment options “no treatment”, “slurry separation”, “anaerobic digestion”, “slurry aeration” and “straw cover” on the emission level was investigated. Approximately 10 m³ of differently treated slurry were stored in pilot scale slurry tanks. Emissions were followed for c. 80 days. After the storage period, slurries were applied to permanent grassland. Greenhouse gas emissions from slurry were mainly caused by methane emissions during storage and by nitrous oxide emissions after field application of manures. Mitigation of GHG emissions can be achieved by a reduction in slurry dry matter and easily degradable organic matter content. Ammonia emissions mainly occurred after field application. Untreated slurry emitted 226.8 g NH₃ m⁻³ and 92.4 kg CO₂ eq. m⁻³ (storage and field application). Slurry separation (liquid fraction and composting of the solid fraction) resulted in NH₃ losses of 402.9 g m⁻³ and GHG losses of 58.5 kg CO₂ eq. m⁻³. Anaerobic digestion was a very effective means to reduce GHG emissions. 37.9 kg CO₂ eq. m⁻³ were lost. NH₃ emissions were similar to those from untreated slurry. Covering the slurry store with a layer of chopped straw instead of a wooden cover increased NH₃ emissions to 320.4 g m⁻³ and GHG emissions to 119.7 kg CO₂ eq. m⁻³. Slurry aeration nearly doubled NH₃ emissions compared to untreated slurry. GHG emissions were reduced to 53.3 kg CO₂ eq. m⁻³.     

Evidence for contact sex recognition pheromone of the Asian longhorned beetle,<Emphasis Type="Italic"> Anoplophora glabripennis</Emphasis> (Coleoptera: Cerambycidae)

Field observations of the Asian longhorned beetle (Anoplophora glabripennis) mating behavior in China suggested that a female-produced contact pheromone was almost certainly involved in sex recognition. Gas chromatography–mass spectrometry (GC-MS) analysis of A. glabripennis adults' whole body cuticular extracts indicates that a series of long-chain hydrocarbons comprise the cuticular waxes of both sexes. Although for the most part the GC profiles are similar for the two sexes, five monounsaturated compounds were consistently more abundant in samples from females than in those from males. These compounds were identified as (Z)-9-tricosene, (Z)-9-pentacosene, (Z)-7-pentacosene, (Z)-9-heptacosene, and (Z)-7-heptacosene in the approximate ratio of 1:2:2:8:1, respectively. Antennal and palpi contact to a polypropylene micro-centrifuge tube coated with a synthetic mixture of the five compounds stimulated copulatory behavior in males.Electronic Supplementary Material  Supplementary material is available for this article if you access the article at . A link in the frame on the left on that page takes you directly to the supplementary material.     

Unusual pheromone chemistry in the navel orangeworm: novel sex attractants and a behavioral antagonist

Using molecular- and sensory physiology-based approaches, three novel natural products, a simple ester, and a behavioral antagonist have been identified from the pheromone gland of the navel orangeworm, Amyelois transitella Walker (Lepidoptera: Pyralidae). In addition to the previously identified (Z,Z)-11,13-hexadecadienal, the pheromone blend is composed of (Z,Z,Z,Z,Z)-3,6,9,12,15-tricosapentaene, (Z,Z,Z,Z,Z)-3,6,9,12,15-pentacosapentaene, ethyl palmitate, ethyl-(Z,Z)-11,13-hexadecadienoate, and (Z,Z)-11,13-hexadecadien-1-yl acetate. The C₂₃ and C₂₅ pentaenes are not only novel sex pheromones, but also new natural products. In field tests, catches of A. transitella males in traps baited with the full mixture of pheromones were as high as those in traps with virgin females, whereas control and traps baited only with the previously known constituent did not capture any moths at all. The navel orangeworm sex pheromone is also an attractant for the meal moth, Pyralis farinalis L. (Pyralidae), but (Z,Z)-11,13-hexadecadien-1-yl acetate is a behavioral antagonist. The new pheromone blend may be highly effective in mating disruption and monitoring programs.     

Sulfide-driven nitrous oxide recovery during the mixotrophic denitrification process

We propose a novel sulfide-driven process to recover N₂O during the traditional denitrification process. The optimum initial sulfide concentration was 120 mg/L, and the N₂O percentage in the gaseous products (N₂O+N₂) was up to 82.9%. Moreover, sulfide involved in denitrification processes could substitute for organic carbon as an electron donor, e.g., 1 g sulfide was equivalent to 0.5-2 g COD when sulfide was oxidized to sulfur and sulfate. The accumulation of N₂O was mainly due to the inhibiting effect of sulfide on nitrous oxide reductase (N₂OR), which was induced by the supply insufficiency of electrons from cytochrome c (cyt c) to N₂OR. When the initial sulfide concentration was 120 mg/L, the N₂OR activity was only 36.8% of its original level. According to the results of cyclic voltammetry, circular dichroism spectra and fluorescence spectra, significant changes in the conformations and protein structures of cyt c were caused by sulfide, and cyt c completely lost its electron transport capacity. This study provides a new concept for N₂O recovery driven by sulfide in the denitrification process. In addition, the findings regarding the mechanism of the inhibition of N₂OR activity have important implications both for reducing emissions of N₂O and recovering N₂O in the sulfide-driven denitrification process.     

Isolines as a new tool to assess the energy costs of the production and distribution of multiple sources of seafood

Consumer-based ocean conservation efforts focus attention on seafood that is produced in an “eco-friendly” manner. However, many species can be produced either in aquaculture operations or harvested within wild capture fisheries, and each mode of production differs in their environmental impacts as well as their energy requirements. Complicating the assessment of eco-friendly seafood is the fact that seafood is a global commodity, the suppliers of which utilize a variety of methods to distribute the product from producer to consumer (e.g. ship, truck, airplane). Like the modes of production, these various modes of distribution differ in their energy intensity. This analysis assesses the overall energy requirements of production and distribution (E_P&D) of seafood to evaluate how the energy costs of distribution influence the total energy cost of seafood produced by different methods. This paper develops the concept of energy isolines as a tool to assess E_P&D. Isolines are a graphical method to succinctly integrate multiple distance assessments so that the best sourcing option can be determined. The isolines are then used to assess how the energy cost of distribution functions as a component of the overall energy cost, and how this influences the E_P&D of a product originating from two different sources with inherently different energy costs of production. Using scallops and salmon as examples, this analysis has revealed that an “eco-friendly” seafood commodity (one produced with less energy) produced far from its destination market could have a higher total E_P&D compared to a local, less “eco-friendly” product (that takes more energy to produce). Finally, this paper evaluates strategies to minimize the overall E_P&D of seafood. Overall, further work on energy audits of seafood focused the need to maintain a global perspective to determine seafood with the lowest overall energy cost of production and distribution.     

Biogenic volatile organic compound analyses by PTR-TOF-MS: Calibration, humidity effect and reduced electric field dependency

Green leaf volatiles(GLVs) emitted by plants after stress or damage induction are a major part of biogenic volatile organic compounds(BVOCs). Proton transfer reaction time-of-flight mass spectrometry(PTR-TOF-MS) is a high-resolution and sensitive technique for in situ GLV analyses, while its performance is dramatically influenced by humidity, electric field,etc. In this study the influence of gas humidity and the effect of reduced field(E/N) were examined in addition to measuring calibration curves for the GLVs. Calibration curves measured for seven of the GLVs in dry air were linear, with sensitivities ranging from 5 to10 ncps/ppbv(normalized counts per second/parts per billion by volume). The sensitivities for most GLV analyses were found to increase by between 20% and 35% when the humidity of the sample gas was raised from 0% to 70% relative humidity(RH) at 21°C, with the exception of(E)-2-hexenol. Product ion branching ratios were also affected by humidity,with the relative abundance of the protonated molecular ions and higher mass fragment ions increasing with humidity. The effect of reduced field(E/N) on the fragmentation of GLVs was examined in the drift tube of the PTR-TOF-MS. The structurally similar GLVs are acutely susceptible to fragmentation following ionization and the fragmentation patterns are highly dependent on E/N. Overall the measured fragmentation patterns contain sufficient information to permit at least partial separation and identification of the isomeric GLVs by looking at differences in their fragmentation patterns at high and low E/N.