A reevaluation of carbon monoxide: past trends,future concentrations,and implications for conformity "hot-spot" policies

Control of CO is one of the great air-quality management success stories of the past 20 years. This paper evaluates whether past progress will continue into the future and whether changes in microscale CO concentrations are comparable to reductions observed at the regional scale. Neighborhood and microscale CO concentrations were evaluated at six northern and southern California monitoring sites. The study also included a review of CO emission, concentration, and exposure trends and on-road motor vehicle-based CO emission control programs for California and the United States. Consistent with California and national trends, CO concentrations declined at each of the six study locations from 1988 through 1998. Microscale concentrations declined at the same rate as did neighborhood-scale concentrations. Rollback analyses demonstrated that microscale concentrations will continue to decline through at least 2010-2020. Within a few years, microscale violations of the CO National Ambient Air Quality Standards (NAAQS) will be unlikely in California except under extraordinary circumstances.     

Synergistic interactions between chemical alarm cues and the presence of conspecific and heterospecific fish shoals

Chemical and visual sources of information are used by aquatic prey during risk assessment. Here, we test the behavioral response of littoral prey fish to combinations of chemical alarm cues (skin extract) and the visual presence of a fish shoal. We scented minnow traps with either alarm cues or water (control) placed inside the trap, a jar that contained either a fish shoal or nothing (control), and recorded the number and species of fish captured. We predicted that chemical alarm cues would reduce the number of fish captured and that a fish shoal would increase the number of fish captured. The predicted effect of chemical and visual cues combined depended on the nature of the interaction. We found that the lowest catch rate was for the combination of alarm cue + no shoal, but the highest catch rate occurred for the combination of alarm cue + shoal. Fish shoal + water had the second highest catch rate and no shoal + water had the second lowest catch rate. We conclude that chemical alarm cues induce area avoidance in the absence of a shoal, but a strong behavioral proclivity to increase shoal cohesion in the presence of a shoal. The presence of a shoal in the traps induced alarmed fish to shoal with them and thus, enter the traps. This occurred even though traps were the source of the alarm cue.Communicated by A. Mathis     

The paradox of risk assessment: comparing responses of fathead minnows to capture-released and diet-released alarm cues from two different predators

Summary. Many aquatic prey are known to use chemical alarm cues to assess their risk of predation. In fishes, such alarm cues can be released either through damage of the epidermis during a predatory attack (capture-released) or through release from the predator feces (diet-released). In our study, we compared the importance of capture- versus diet-released alarm cues in risk assessment by fathead minnows (Pimephales promelas) that were na?ve to fish predators. We utilized two different fish predators: a specialized piscivore, the northern pike (Esox lucius) and a generalist predator, the brook trout (Salvelinus fontinalis). Handling time of pike consuming minnows was much shorter than for trout consuming minnows, likely resulting in less epidermal damage to the minnows during attacks by pike. In accordance with this, minnows showed a less intense antipredator response to capture-released cues from pike than capture-released cues from trout. This represents a paradox in risk assessment for the minnows as they respond to the specialized piscivore, the more dangerous predator, with a less intense antipredator response. In contrast, the minnows showed a stronger antipredator response to the specialized piscivore than to the generalist when given diet cues. This work highlights the need for researchers to carefully consider the nature of the information available to prey in risk assessment.     

Mate guarding,copulation strategies and paternity in the sex-role reversed,socially polyandrous red-necked phalarope<Emphasis Type="Italic"> Phalaropus lobatus</Emphasis>

In a recent review, Westneat and Stewart (2003) compiled evidence that extra-pair paternity results from a three-player interaction in which sexual conflict is a potent force. Sequentially polyandrous species of birds appear to fit this idea well. Earlier breeding males may attempt to use sperm storage by females to obtain paternity in their mates subsequent clutches. Later-breeding males may consequently attempt to avoid sperm competition by preferring to pair with previously unmated females. Females may bias events one way or the other. We examined the applicability of these hypotheses by studying mating behavior and paternity in red-necked phalaropes (Phalaropus lobatus), a sex-role reversed, socially polyandrous shorebird. Male red-necked phalaropes guarded mates more strongly than other shorebirds. Males increased within-pair copulation attempts during their mates fertile period, and maintained or further increased attempts towards the end of laying, suggesting an attempt to fertilize the females next clutch; these attempts were usually thwarted by the female. Paired males sought extra-pair copulations with females about to re-enter the breeding pool. Multilocus DNA fingerprinting showed that 6% of clutches (4/63) each contained one chick sired by a male other than the incubator, producing a population rate of these events of 1.7% (n=226 chicks). Male mates had full paternity in all first clutches (n=25) and 15 of 16 monogamous replacement clutches. In contrast, 3 of 6 clutches of second males contained extra-pair young likely fathered by the females previous mate. Previously mated female phalaropes may employ counter-strategies that prevent later mating males from discriminating against them. The stability of this polyandrous system, in which males provide all parental care, ultimately may depend on females providing males with eggs containing primarily genes of the incubating male, and not a previous mate.Communicated by M. Webster     

Positive perceptions of green and open space as predictors of neighbourhood quality of life: implications for urban planning across the city region

The provision of green and open space in the face of wider development pressure is a key urban challenge. Despite this, few studies have critically investigated the quality of life implications of such provision. This paper focuses on perceptions of built environment factors and their influence on neighbourhood quality of life. Data are drawn from a household survey questionnaire completed by 483 residents living in three neighbourhoods in Dublin, Ireland – an inner city neighbourhood, a suburb and a peri-urban settlement. Positive perceptions of green and open space were identified as important predictors of high levels of neighbourhood satisfaction, surpassed only by dwelling characteristics. This suggests that development strategies which fail to provide for properly planned green and open spaces may be detrimental to neighbourhood quality of life. Furthermore, the results suggest a need for design solutions which consider neighbourhood typology in achieving improved neighbourhood quality of life.     

三峡库区澎溪河回水区溶解态金属离子来源和时空分布特征分析

以三峡库区北岸最大支流澎溪河的高阳平湖段为例,探讨随着调水方式导致的水位变化,三峡库区支流金属离子Ca、Zn、Fe、Cr、Pb、Cu和Hg等在时间、水平和垂直空间维度上的分布和动态.在2013年6月5日~2014年5月29日为期1 a的采样周期内于澎溪河长年回水区高阳平湖的4个采样点采样共21次,平均每17.3 d采集一次.水体样品分别采自水体表层(0~0.5 m)、中层和底层(底泥以上0.5 m).冬季水体不分层期间,中层样品采自水深1/2处,分层时则采自温跃层.应用RBR-80220型水质自动分析仪监测各样点水温、电导率、水深等数据.水样采用冷原子吸收法和电感耦合等离子体原子发射光谱法(ICP-AES)测定各金属质量浓度.运用Excel、SPSS软件进行数据统计分析;以Hg离子为例,利用Matlab软件构建各水位时期金属离子质量浓度分布三维柱状图.结果表明:(1)从水体可溶性金属离子质量浓度角度,澎溪河水质总体较好,Cr、Pb、Cu、Zn和Hg等离子均低于地表水环境质量标准(GB3838-2002)Ⅲ类水质标准相应离子质量浓度;(2)在来源上,Cr、Pb和Cu等离子来源于干流回水;Fe和Zn离子来源于澎溪河内源;Hg离子来源受干流回水和内源影响.金属离子随着温度分层出现质量浓度分层现象;(3)影响高阳平湖电导率的主要物质是非金属离子.     

Theoretical and Observational Assessments of Flare Efficiencies

ABSTRACT

Flaring of waste gases is a common practice in the processing of hydrocarbon (HC) materials. It is assumed that flaring achieves complete combustion with relatively innocuous byproducts such as CO₂ and H₂O. However, flaring is rarely successful in the attainment of complete combustion, because entrainment of air into the region of combusting gases restricts flame sizes to less than optimum values. The resulting flames are too small to dissipate the amount of heat associated with 100% combustion efficiency.

Equations were employed to estimate flame lengths, areas, and volumes as functions of flare stack exit velocity, stoichiometric mixing ratio, and wind speed. Heats released as part of the combustion process were then estimated from a knowledge of the flame dimensions together with an assumed flame temperature of 1200 K. Combustion efficiencies were subsequently obtained by taking the ratio of estimated actual heat release values to those associated with 100% complete combustion.

Results of the calculations showed that combustion efficiencies decreased rapidly as wind speed increased from 1 to 6 m/sec. As wind speeds increased beyond 6 m/sec,combustion efficiencies tended to level off at values between 10 and 15%. Propane and ethane tend to burn more efficiently than do methane or hydrogen sulfide because of their lower stoichiometric mixing ratios.

Results of theoretical predictions were compared to nine values of local combustion efficiencies obtained as part of an observational study into flaring activity conducted by the Alberta Research Council (ARC). All values were obtained during wind speed conditions of less than 4 m/sec. There was generally good agreement between predicted and observed values. The mean and standard deviation of observed combustion efficiencies were 68 ± 7%. Comparable predicted values were 69 ± 7%.     

Variation of cholinergic biomarkers in brain regions and blood components of captive mink

Studies are increasingly using cholinergic parameters as biomarkers of early neurotoxicity, but few have characterized this system in ecologically relevant model organisms. In the present study, key neurochemicals in the cholinergic pathway were measured and analyzed from discrete parts of brain and blood from captive mink (Mustela vison). Similar to other mammals, the regional distribution of cholinergic parameters in the brain could be ranked from highest to lowest as: basal ganglia > occipital cortex > brain stem > cerebellum (F _3,192?=?172.1, p?<?0.001). Higher variation in cholinergic parameters was found in the cerebellum (coefficient of variation = 34.9%), and the least variation was measured in the brain stem (19.7%). Variation was also assessed by calculating the difference between the lowest and highest measures among individual animals: choline acetyltransferase (1.6× fold difference), cholinesterase (2.0×), muscarinic receptor levels (2.4×), acetylcholine (3.7×), nicotinic receptor levels (3.9×), and choline transporter (5.0×). In blood samples, activity and inter-individual variation of cholinesterase was highest in whole blood and lowest in plasma and serum. By using captive mink of a common genetic source, age, gender, and rearing conditions, these data help establish normal levels, ranges, and variations of cholinergic biomarkers among brain regions, blood components, and individual animals. Such information may better enable the utility of cholinergic biomarkers in environmental assessments.     

Predicting categories of drugs used by suspected drug-impaired drivers using the Drug Evaluation and Classification Program tests

Objective: The purpose of this study was to statistically determine which combination(s) of drug-related signs and symptoms from the Drug Evaluation and Classification (DEC) protocol best predict the drug category used by the suspected drug-impaired driver.

Methods: Data from 1,512 completed DEC evaluations of suspected impaired drivers subsequently found to have ingested central nervous system (CNS) depressants, CNS stimulants, narcotic analgesics, and cannabis were analyzed using a multinomial logistic regression procedure. A set of evaluations completed on drug-free subjects was also included. The relative importance of clinical, behavioral, and observational measures in predicting drug categories responsible for impairment was also examined.

Results: Thirteen drug-related indicators were found to significantly contribute to the prediction of drug category, including being under the care of a doctor or dentist, condition of the eyes, condition of the eyelids, mean pulse rate, assessment of horizontal gaze nystagmus (HGN), convergence, performance on the One Leg Stand (OLS) Test, eyelid tremors, pupil size in darkness, reaction to light, presence of visible injection sites, systolic blood pressure, and muscle tone. Indicators related to the appearance and physiological response of the eye contributed the most to the prediction of drug category, followed closely by clinical indicators and performance on the psychophysical tests.

Conclusions: The findings from this study suggest that drug recognition experts (DREs) should be careful to review a set of key signs and symptoms when determining the category of drug used by suspected drug-impaired drivers. Drug use indicators related to the appearance and physiological response of the eye were found to contribute the most to the prediction of the drug category responsible for the impairment. These results could help form the basis of a core set of indicators that DREs could initially consult to form their opinion of drug influence. This in turn may enhance the validity, effectiveness, and efficiency of drug detection and identification by DREs and lead to a more effective and efficient DEC program, improved enforcement of drug-impaired driving, and greater acceptance of the DEC program by the courts.