Intergenerational Impartiality: Replacing Discounting by Probability Weighting

Intergenerational impartiality requires putting the welfare of future generations at par with that of our own. However, rational choice requires weighting all welfare values by the respective probabilities of realization. As the risk of non-survival of mankind is strictly positive for all time periods and as the probability of non-survival is cumulative, the probability weights operate like discount factors, though justified on a morally justifiable and completely different ground. Impartial intertemporal welfare maximization is acceptable, though the welfare of people in the very far future has lower effects as the probabilities of their existence are also lower. However, the effective discount rate on future welfare values (distinct from monetary values) justified on this ground is likely to be less than 0.1 per annum. Such discounting does not compromise environmental protection and sustainability unduly. The finiteness of our universe implies that the sum of our expected welfare to infinity remains finite, solving the paradox of having to compare different infinite values in optimal growth/conservation theories.     

Bioaccumulation of platinum group metals on some fish species ( Oreochromis niloticus,Penaeus laspisulcates,Scylla serrate,Galaxias brevipinnis and Mollusc ) in the Pra estuary of Ghana

Catalytic converters have been designed to solve the problem of pollution from automobiles. However, recent studies have shown that the platinum group metals (PGMs) that are used in the design are being deposited alongside highways. The objective of this study was to measure the levels of PGMs that bioaccumulate in Oreochromis niloticus, Penaeus laspisulcates, Scylla serrate, Galaxias brevipinnis and Mollusc in the river Pra estuary along a major highway in Ghana. Chemical analysis using neutron activation analysis showed accumulation of the PGMs in all the biota species analysed. The S. serrate and mollusc showed higher accumulation than the other species. The mollusc and the other fish species in the estuary are consumed in Ghana, and therefore there is the need to educate the population on the effect of the PGMs on their health.     

Experimental investigation of the effect of sediment transport patterns on the adsorption of cadmium ions onto sediment particles

The mechanism of flow turbulence, sediment supply conditions, and sediment transport patterns that affect the adsorption of cadmium ions onto sediment particles in natural waters are experimentally simulated and studied in this study both in batch reactors and in a turbulence simulation tank. By changing the agitation conditions, the sediment transport in batch reactors can be categorized into bottom sediment-dominated sediment and suspended sediment-dominated sediment. It is found that the adsorption rate of bottom sediment is much less than that of suspended sediment, but the sediment transport pattern does not affect the final (equilibrium) concentration of dissolved cadmium. This result indicates that the parameters of an adsorption isotherm are the same regardless of the sediment transport pattern. In the turbulence simulation tank, the turbulence is generated by harmonic grid-stirred motions, and the turbulence intensity is quantified in terms of eddy diffusivity, which is equal to 9.84F(F is the harmonic vibration frequency) and is comparable to natural surface water conditions.When the turbulence intensity of flow is low and sediment particles stay as bottom sediment, the adsorption rate is significantly low, and the adsorption quantity compared with that of suspended sediment is negligible in the 6 h duration of the experiment. This result greatly favors the simplification of the numerical modeling of heavy metal pollutant transformation in natural rivers. When the turbulence intensity is high but bottom sediment persists, the rate and extent of descent of the dissolved cadmium concentration in the tank noticeably increase, and the time that is required to reach adsorption equilibrium also increases considerably due to the continuous exchange that occurs between the suspended sediment and the bottom sediment.A comparison of the results of the experiments in the batch reactor and those in the turbulence simulation tank reveals that the adsorption ability of the sediment, and in particular the adsorption rate, is greatly over-estimated in the batch reactor.     

EFFECTS OF BUILDING CONSTRUCTION NOISE ON RESIDENTS: A QUASI-EXPERIMENT

Noise pollution is an environmental problem in cities. Although recent field research has focused on transportation noises, the effects of exposure to building construction noise have not been studied. In a quasi-experiment, residents of a three-wing residence hall for female students located near a construction site served as subjects in three comparison groups. Information about their personal characteristics and perceived effects of construction noise on studying and other behaviours were gathered in a questionnaire (n=94) and an activity log (n=14). In addition, sound level measurements and records of resident turnover and systematic observations of windows open or closed were analysed. As expected, the results of chi-square tests, one-way ANOVAs and MANOVAs show significant wing effects (p<0·05) on frequency heard, distractability, and several perceived behavioural effects, such as being awakened, difficulty with relaxation and studying-related activities, and interference with conversation and television-watching. These effects were significantly more severe for residents closest to the construction site than those further away. Residents coped with noise by speaking louder, keeping windows closed, and leaving the room.     

碳源对含盐废水短程硝化反硝化的影响

分别采用醋酸钠、甘油、乙醇和葡萄糖作为外加碳源,研究不同碳源对含盐废水短程硝化反硝化的影响.结果表明:(1)利用醋酸钠作为碳源,逐步增加NaCl盐度可以实现短程硝化反硝化,TN平均去除率高于95％.当NaCl盐度为14.2 g/L时,采用醋酸钠、甘油、乙醇和葡萄糖作为碳源时,NO2- -N的累积率分别为98.7％、86...     

广州市大气中过氧化物的研究

采用高效液相色谱(HPLC)荧光法于1998年7月和10月测定了广州市大气中的5种过氧化 物:过氧化氢(H₂O₂)、羟甲基过氧化氢(HMHP)、甲基过氧化氢(MHP)、1-羟乙基过氧化氢(1-H EHP)及乙基过氧化氢(EHP).其中主要过氧化物是H₂O₂、HMHP和MHP,其最高浓度分别为1.6(10 ^-9、0.67(10^-9和0.54(10^-9(V/V).在光照强,相对湿度低的情况下,H₂O₂和MHP呈现明显的日 变化规律,早晚浓度低,最大值多出现在14:00～16:00.同时测定了大气温度,湿度和紫外辐射U VB及大气中O₃, NO_X和SO₂,发现H₂O₂和MHP与O₃、温度和UVB具有一定的正相关关系,而与NO_X, SO₂ 和相对湿度具有一定的负相关关系.     

吸气式感烟火灾探测系统采样管网模拟仿真

通过对吸气式感烟火灾探测系统采样管网进行流体力学分析,建立了采样管网系统力学数学模型,采用了面向对象的编程技术,编制了工程管网设计模拟仿真软件,实现各采样点的探测灵敏度及探测响应时间的计算和对采样孔径的优化调整,在实际应用中取得良好效果。