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171.
Ning B  Graham NJ  Zhang Y 《Chemosphere》2007,68(6):1173-1179
The indirect reaction of octylphenol (OP) and nonylphenol (NP) with hydroxyl radicals (*OH) during ozonation was investigated at pH values ranging from 6 to 9. A parameter Rct, representing the ratio of the *OH-exposure to the ozone-exposure, was measured using a method involving a low concentration of p-chlorobenzoic acid as a *OH-probe compound during the ozonation. By assuming that Rct is a constant value at a given pH, the second order rate constants of the alkylphenol reaction with hydroxyl radicals were determined as 1.4(+/-0.2) x 10(10) and 1.1(+/-0.2) x 10(10) M(-1) s(-1) for OP and NP, respectively. The proportions of each alkylphenol degraded by direct molecular ozone reaction and indirect hydroxyl radical reaction were predicted at different pH values. The contribution of indirect *OH reactions with each AP was found to represent over 50% of the total degradation for pH approximately 7, and the contribution increases substantially with pH>7.  相似文献   
172.
The major inorganic and organic osmolytes responsible for hydrating the oocytes during pre-ovulatory meiotic maturation in autumn- and spring-spawning stocks of Atlantic herring are examined. Despite the ovulated eggs of spring-spawning herring being 1.6- to 2-fold larger than the autumn-spawning stock, the GSI (27 ± 3%) and degree of oocyte hydration (70–72% water) were similar. Normalising the data with respect to dry mass revealed that the physiological mechanisms underlying the maturational influx of water were the same for both classes of egg. Cl, K+ and Pi together with a small pool of free amino acids (FAA) represented the driving forces for oocyte hydration. K+ (autumn and spring) and Pi (spring) maintained their concentrations in the ovulated eggs, while all other ions, including Cl, Na+, NH4 + and Mg2+ were significantly diluted. In contrast the FAA concentration increased during the hydration process. Amongst the inorganic ions, Cl showed the greatest increase in the ovulated eggs. The FAA content doubled from 1.5 to 3.3% of dry mass during oocyte hydration and accounted for 29% of the calculated ovoplasmic osmolality in the ovulated eggs from both autumn- and spring-spawners. This significant osmotic effect of the small pool of FAA was due to the low water content of the benthic eggs. The differential movement of the inorganic and organic osmolytes that underly oocyte hydration in Atlantic herring are discussed in relation to current models of transmembrane ion flux.  相似文献   
173.
To investigate how bumblebees (Bombus terrestris) learn the complex motor skills involved in pollen foraging, we observed naïve workers foraging on arrays of nectarless poppy flowers (Papaver rhoeas) in a greenhouse. Foraging skills were quantified by measuring the pollen load collected during each foraging bout and relating this to the number of flowers visited and bout duration on two consecutive days. The pollen standing crop (PSC) in each flower decreased drastically from 0530 to 0900 hours. Therefore, we related foraging performance to the changing levels of pollen available (per flower) and found that collection rate increased over the course of four consecutive foraging bouts (comprising between 277 and 354 individual flower visits), suggesting that learning to forage for pollen represents a substantial time investment for individual foragers. The pollen collection rate and size of pollen loads collected at the start of day 2 were markedly lower than at the end of day 1, suggesting that components of pollen foraging behaviour could be subject to imperfect overnight retention. Our results suggest that learning the necessary motor skills to collect pollen effectively from morphologically simple flowers takes three times as many visits as learning how to handle the most morphologically complex flowers to extract nectar, potentially explaining why bees are more specialised in their choice of pollen flowers.  相似文献   
174.
In the HYENA study (HYpertension and Exposure to Noise near Airports) noise annoyances due to aircraft and road traffic noise were assessed in subjects that lived in the vicinity of 6 major European airports using the 11-point ICBEN scale (International Commission on Biological Effects of Noise). A distinction was made between the annoyance during the day and during the night. Lden and Lnight were considered as indicators of noise exposure. Pooled data analyses showed clear exposure–response relationships between the noise level and the noise annoyance for both exposures. The exposure–response curves for road noise were congruent with the EU standard curves used for predicting the number of highly noise annoyed subjects in European communities. Annoyance ratings due to aircraft noise, however, were higher than predicted by the EU standard curves. The data supports other findings suggesting that the people's attitude towards aircraft noise has changed over the years, and that the EU standard curve for aircraft noise should be modified.  相似文献   
175.
MTBE, a fuel oxygenate added to gasoline in parts of the USA, appears to have imposed significant adverse impacts on groundwater. In the UK, the impacts of MTBE are not well known in part because insufficient data has been presented to allow an accurate assessment. With the recognition of urban groundwater as a potentially valuable resource due to the growing pressure on rural groundwater, there is need for pollution risks to urban groundwater to be evaluated for contaminants such as MTBE. This paper presents the application of a risk-based water management tool called Borehole Optimisation System (BOS) in the evaluation of the risk of MTBE to urban groundwater at city scale using Nottingham city as our case study. The risk model was validated by comparison of its predictions with observations of MTBE detections for about 1100 boreholes in England and Wales. The output of the risk analysis was the production of a map showing the predicted MTBE concentration at all locations in the city. The results indicate that MTBE does not currently pose a major risk to urban groundwater although there may be a potential risk to groundwater in the southern part of the city where most industries are concentrated.  相似文献   
176.
This paper summarises the methodology and results of work involved in the investigation of energy demand in six Chinese villages included in the SUCCESS Project. The procedures used to collect data associated with local energy demand are explained and the approach to data analysis is explained. Results are provided in terms for delivered energy consumption, as an indicator of energy demand; primary energy consumption, as an indicator of energy resource depletion; and carbon dioxide emissions, as an indicator of global climate change. Similarities and differences between results for this sample of villages are considered. The important causes of differences in results are investigated.  相似文献   
177.
The emergence of problems such as nitrate pollution has drawn attention to the need for integrated management of land and water resources. Integrated management approaches require appropriate institutional arrangements. Unfortunately, in many countries, land and water resources are managed on a sectoral basis and institutions were not designed to deal with complex environmental problems. Institutional arrangements for management of nitrate pollution are evaluated on the basis of seven criteria. Results indicate that some progress was made after 1985 regarding inter-agency co-ordination, public participation, the mix of strategies and adaptive capacity. Nevertheless, key substantive issues involving equity, efficiency and effectiveness were not adequately resolved. Policy referral, catchment management planning, bargaining and negotiation are recommended as key processes and mechanisms for improved management of the nitrate problem.  相似文献   
178.
Night-time OH levels have been determined for UK urban surface environments using two methods,the decay and steady state approximation methods.Measurement data from the UK National Environmental Technology Centre archive for four urban sites(Bristol,Harwell,London Eltham and Edinburgh) over the time period of 1996 to 2000 have been used in this study.Three reactive alkenes,namely isoprene,1,3-butadiene and trans-2-pentene were chosen for the calculation of OH levels by the decay method.Hourly measurements o...  相似文献   
179.
ABSTRACT: Fecal contamination and organic pollution of an agricultural drainage in northeast Indiana was high. Bacterial counts (total coliform, TC; fecal coliform, FC; and fecal streptococcus, FS) and biochemical oxygen demand (BOD) were used to assess waste concentrations. Coliform counts indicated that sections of the drainage receiving septic effluent had waste concentrations far in excess of public health standards (mean FC = 550,000/100 ml). Areas of drainage remote from septic tank pollution were found to occasionally meet federal public health standards for whole body contact recreation but generally these areas had twice the allowable limit of 200 FC/100 ml. Bacterial contamination was highest during runoff events when the median values for TC, FC, and FS were 5, 3, and 17 times greater, respectively, than the median values during low stream discharge. Surface flows carried contaminants from unconfined livestock operations and fecally contaminated sediment was transported by high waters. During one runoff event a BOD loading of 36.7 kg/km2 was recorded and the peak BOD concentration observed was 16 mg/l. A discharge of liquid manure from a confined livestock operation caused a major fish kill. Pollution from septic tanks and unconfined livestock is greatest at high stream discharge when dilution reduces the impact on aquatic life.  相似文献   
180.
This paper is concerned with the effects of advanced manufacturing technology on shopfloor operator jobs and work attitudes. A strong line of argument from labour process theory suggests that such technology will simplify and deskill jobs, and reduce the quality or working life. This proposition was explored within a large electronics company which assembles computer boards, where two different applications of information technology have been experienced. These were compared with two traditional manual assembly jobs. Assessment of job content, perceived job characteristics and operator work attitudes, showed no uniform deskilling effects of advanced manufacturing technologies. Much larger differences existed both between the different new technology applications and between the traditional jobs. This demonstrates that choice of technology is important to skill use and employees' attitudes, as are the choices for the organization of work around it. These are not uniform processes even within a single organization. Experience of operating advanced manufacturing technology was also accompanied by more positive views concerning its impact on the shopfloor.  相似文献   
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