An optimized approach for estimating benzene in ambient air within an air quality monitoring network

Benzene is a carcinogenic air pollutant for which European legislation has set an annual limit and criteria for the number of fixed monitoring sites within air quality networks（AQMN）. However, due to the limited number of fixed sites for benzene measurement, exposure data are lacking. Considering the relationship between benzene levels and other variables monitored within an AQMN, such as NO₂, O₃, temperature, solar radiation, and accumulated precipitation, this study propo...     

Breeding Periodicity for Male Sea Turtles,Operational Sex Ratios,and Implications in the Face of Climate Change

Abstract: Species that have temperature‐dependent sex determination (TSD) often produce highly skewed offspring sex ratios contrary to long‐standing theoretical predictions. This ecological enigma has provoked concern that climate change may induce the production of single‐sex generations and hence lead to population extirpation. All species of sea turtles exhibit TSD, many are already endangered, and most already produce sex ratios skewed to the sex produced at warmer temperatures (females). We tracked male loggerhead turtles (Caretta caretta) from Zakynthos, Greece, throughout the entire interval between successive breeding seasons and identified individuals on their breeding grounds, using photoidentification, to determine breeding periodicity and operational sex ratios. Males returned to breed at least twice as frequently as females. We estimated that the hatchling sex ratio of 70:30 female to male for this rookery will translate into an overall operational sex ratio (OSR) (i.e., ratio of total number of males vs females breeding each year) of close to 50:50 female to male. We followed three male turtles for between 10 and 12 months during which time they all traveled back to the breeding grounds. Flipper tagging revealed the proportion of females returning to nest after intervals of 1, 2, 3, and 4 years were 0.21, 0.38, 0.29, and 0.12, respectively (mean interval 2.3 years). A further nine male turtles were tracked for short periods to determine their departure date from the breeding grounds. These departure dates were combined with a photoidentification data set of 165 individuals identified on in‐water transect surveys at the start of the breeding season to develop a statistical model of the population dynamics. This model produced a maximum likelihood estimate that males visit the breeding site 2.6 times more often than females (95%CI 2.1, 3.1), which was consistent with the data from satellite tracking and flipper tagging. Increased frequency of male breeding will help ameliorate female‐biased hatchling sex ratios. Combined with the ability of males to fertilize the eggs of many females and for females to store sperm to fertilize many clutches, our results imply that effects of climate change on the viability of sea turtle populations are likely to be less acute than previously suspected.     

川牛膝种子保存技术初探

对川牛膝种子开展室温常规贮藏、室温湿沙贮藏、室温超干燥贮藏、4℃低温贮藏、冷冻贮藏等5种贮藏试验,结果表明：①室温湿沙贮藏是川牛膝种子短期保存的最优方法,能显著提高种子发芽率,其值较常规保存高14.5％;其次为4℃低温贮藏.②冷冻贮藏是川牛膝种子长期保存的最佳方法,保存3年后当其他保存方式的种子寿命几乎丧失时,其生活力及发芽率仍保持在较高水平,分别为60.3％和49.9％;其次为超干燥贮藏,种子生活力和发芽率分别为51.3％和41.2％.     

基于数字锁相技术的飞机货舱火灾烟雾光学参数方法研究*

为解决飞机货舱火灾光学探测易受环境杂光和空气中灰尘、水汽干扰,误报率高的问题,提出1种基于数字锁相的双波长火灾烟雾探测方法。利用数字锁相技术调制双波长光源,选择性地提取微弱光散射信号,并设计前、后双向散射光探测光路。采用常见火灾材料及干扰源进行真假火源实验,依据米氏散射理论及不同粒径气溶胶颗粒对不同波长光的散射效应差异,以不对称比（AR）和双波长光强比（DWIR）作为火灾检测参数对不同粒径颗粒进行区分,根据2种火灾检测参数建立数据样本,利用BP神经网络进行分析,并加入复合式传感器实验作为对比。研究结果表明:基于数字锁相技术的火灾烟雾光学探测方法能够在一定程度上区分火灾烟雾和干扰源,误报率小于3.5%。     

超音速气动液滴荷电雾化及降尘性能试验研究*

为探究煤炭生产过程中呼吸性粉尘难以捕捉且对人体造成伤害的问题,提出超音速水雾荷电降尘技术。基于荷电雾化机理,研究电极环直径、电极间距、电压3因素对超音速气动液滴荷电、雾化效果的影响。利用网状目标法测量雾滴群电流并计算荷质比,采用SPSS软件分析3因素与雾滴荷质比之间的相关性,并用激光粒度仪测量雾滴粒径。最后,采用最优荷电雾化参数进行喷雾降尘试验。研究结果表明:各因素对荷电效果的影响次序为:电压>电极间距>电极环直径;雾滴粒径随电压的升高而减小,随电极间距的增大先增大后减小,随电极环直径的增大先减小后增大;当电压12 kV,电极间距2.5 cm,电极环直径6 cm时,超音速荷电水雾降尘效果最佳,与普通水雾降尘相比,全尘降尘效率提高12.4%,呼尘降尘效率提高49.6%。     

Biased primary sex ratio in the bushcricket Poecilimon veluchianus,an insect with sex chromosomes

Offspring sex ratio at hatching was examined in the bushcricket Poecilimon veluchianus. Offspring sex ratios varied significantly between females (Fig. 1). Low mortality prior to sex determination established that this heterogeneity was already present in the primary offspring sex ratio. Sperm age and female age had no influence on offspring sex ratio (Fig. 2). Male age at copulation, however, correlated significantly with offspring sex ratio (Fig. 3). There were two types of males: one type produced predominantly daughters when young and an increasing proportion of sons with age. The other type produced, independent of age, 1:1 offspring sex ratios (Fig. 4). The two types of males seem to occur in approximately equal numbers. Sex ratio variation (1) may adaptively compensate for local sex ratio biases caused by sex-specific motility, or (2) it may be adaptive if there is a sex-differential effect of laying date on offspring fitness. Received: 14 March 1996/Accepted after revision: 24 June 1996     

Recognition of water masses according to geochemical signatures in the Central Mediterranean sea: Y/Ho ratio and rare earth element behaviour

This study reports the results of geochemical investigations carried out in the Strait of Sicily (Central Mediterranean Sea) during the oceanographic cruise BANSIC 2000, focusing on the area around the Pantelleria Island. We evaluate the interface processes between dissolved phase and suspended particulate matter in the water columns on the basis of Y/Ho ratio and rare earth elements and yttrium distributions that are suitable to trace the occurrence of different water layers in Central Mediterranean Area. The main source of trace elements to the sea water system was recognized in the atmospheric fallout, while different scavenging mechanisms among Y and rare earth elements occur. Cation exchange at the dissolved phase-suspended media interface is driven by their external electronic configurations as monitored through the Y/Ho ratios, shape, and amplitude of the tetrad effects calculated along the water columns. The shape and amplitude of the tetrad effects in bottom waters suggest that the preferential Y scavenging from deep water layers depends on the hydrothermal activity in the seafloor. Here, Y is surface-complexed through the formation of inner-sphere complexes; Ho and other heavy rare earth elements are sorbed onto suspended particulate matter surfaces as weak outer-sphere complexes; these materials have a montmorillonite like nature; and preferential incorporation medium rare earth elements in crystal structures of biogenic carbonates is suggested by the relationship between the Eu anomaly and the nutrient contents of water masses.     

Independent effects of male and female density on sexual harassment, female fitness, and male competition for mates in the western mosquitofish Gambusia affinis

Operational sex ratio (the ratio of sexually active males to fertilizable females) has a major influence on male competition for mates and male–female interactions. The contributions of male and female density per se to mating system dynamics, however, are rarely examined, and the fitness consequences are often inferred rather than quantified. Male mosquitofish (Gambusia affinis) compete aggressively and frequently harass females for copulations, a behavior thought to reduce female fitness. Female fitness can also be reduced by increases in female density, which may affect food availability, cannibalism rates, and chemical interactions between females. I manipulated male and female densities of G. affinis to measure their effects on male–male aggression, male harassment toward females, and female fitness. I found that males chased rivals more often and attempted fewer copulations when female density decreased, but surprisingly male density had no significant effect on the frequency of these male behaviors. In contrast, males’ agonistic displays toward other males increased with male density, but display behavior was unaffected by female density. These results suggest that male and female density do not always contribute equally or at all to the patterns of behavior we observe. Female fitness declined as female density increased, the opposite pattern expected if male harassment is costly to females. This suggests that a strong, negative effect of female density overwhelmed any potential costs of male harassment. Sources of female density dependence and the consequences of changes in male and female density to patterns of male behavior are discussed.     

积分比值法计算室内火灾烟气层分界面高度值的研究

在室内火灾双区域模型中,对火灾烟气层分界面高度值的判定具有重要意义,对其计算方法进行了研究。鉴于烟熏痕迹法和N百分比法存在的主观性和经验性的局限,介绍了一种积分比值法,给出了计算公式并采用Fortran95实现了编程计算。通过FDS5.0模拟了一种火灾场景,根据模拟得到的不同高度处的温度均值,应用积分比值法计算出了烟气层高度值,并将其与模拟得到的烟气层高度值进行了比较,结果表明两者较为吻合,应用积分比值法计算烟气层高度是可行的、准确的。     

A comparison on the phytoremediation ability of triazophos by different macrophytes

The strategy of choosing suitable plants should receive great performance in phytoremediation of surface water polluted by triazophos(O,O-diethyl-O-(1-phenyl-1,2,4-triazol-3-base) sulfur phosphate, TAP), which is an organophosphorus pesticide widespread applied for agriculture in China and moderately toxic to higher animal and fish. The tolerance, uptake, transformation and removal of TAP by twelve species of macrophytes were examined in a hydroponic system and a comprehensive score(CS) of five parameters(relative growth rate(RGR), biomass, root/shoot ratio, removal capacity(RC), and bio-concentration factor(BCF)) by factor analysis was employed to screen the potential macrophyte species for TAP phytoremediation. The results showed that Thalia dealbata, Cyperus alternifolius, Canna indica and Acorus calamus had higher RGR values, indicating these four species having stronger growth capacity under TAP stress. The higher RC loading in Iris pseudacorus and Cyperus rotundus were 42.11 and 24.63 μg/(g fw·day), respectively. The highest values of BCF occurred in A. calamus(1.17), and TF occurred in Eichhornia crassipes(2.14). Biomass and root/shoot ratio of plant showed significant positive correlation with first-order kinetic constant of TAP removal in the hydroponic system, indicating that plant biomass and root system play important roles in remediation of TAP. Five plant species including C. alternifolius, A. calamus, T. dealbata, C. indica and Typha orientalis, which owned higher CS, would be potential species for TAP phytoremediation of contaminated water bodies.