A statistical approach to estimate O3 uptake of ponderosa pine in a mediterranean climate

In highly polluted sites, stomatal behavior is sluggish with respect to light, vapor pressure deficit, and internal CO2 concentration (Ci) and poorly described by existing models. Statistical models were developed to estimate stomatal conductance (gs) of 40-year-old ponderosa pine at three sites differing in pollutant exposure for the purpose of calculating O3 uptake. Gs was estimated using julian day, hour of day, pre-dawn xylem potential and photosynthetic photon flux density (PPFD). The median difference between estimated and observed field gs did not exceed 10 mmol H2O m(-2) s(-1), and estimated gs within 95% confidence intervals. 03 uptake was calculated from hourly estimated gs, hourly O3 concentration, and a constant to correct for the difference in diffusivity between water vapor and 03. The simulation model TREGRO was also used to calculate the cumulative 03 uptake at all three sites. 03 uptake estimated by the statistical model was higher than that simulated by TREGRO because gas exchange rates were proportionally higher. O3 exposure and uptake were significantly correlated (r2>0.92), because O3 exposure and gs were highly correlated in both statistical and simulation models.     

Externalities, Floating Population and Spatial Agglomeration

With the further development of socialist market economy, the mobility of factor markets in China, especially the labor market, is strengthened. Externalities interacts with the agglomeration of productive factors. Under the framework of new economic geography, this article presents a theoretical model involving the endogenous population density affected by urban externalities. Results show that the population density is more concentrated around the center because the degree and extent of interaction between individuals intensifies when the distance from the center decreases. When there are several externalities resources, the aggregation of externalities changes the configuration of spatial factor allocation. These results fit well with the empirical facts about the decreasing density of floating population along the cities of Guangzhou, Dongguan and Shenzhen in Guangdong Province which is situated in the eastern coast of the Pearl River Delta. We fred that under the impacts of externalities released from Hong Kong into the coast, floating population was more concentrated around Shenzhen and Dongguan, which are more adjacent to Hong Kong compared with Guangzhou City.     

High Environmental Cost behind Low China Price

China has won the name of the world factory being famous for exporting a great deal of and various kinds of low-price merchandise. However, most of Chinese exports are primary goods or manufactured products that create heavy pollution and require intensive use of resources. Chinese products go abroad, but their following harms stay behind. The article analyzes many obvious low-price facts in China and their concomitant terrible environmental results in detail, and points out that there are huge hidden troubles in the way of China＇s sustainable development behind her seemingly flourishing economy.     

我国核电站对渔业资源的影响及其对策

本文主要介绍核电站废热水进入鱼体后引起的致死率的预评价和预防对策。     

Effects of artificially induced complete mixing on dissolved organic matter in a stratified source water reservoir

Naturally complete mixing promotes the spontaneous redistribution of dissolved oxygen(DO), representing an ideal state for maintaining good water quality, and conducive to the biomineralization of organic matter. Water lifting aerators(WLAs) can extend the periods of complete mixing and increase the initial mixing temperature. To evaluate the influence of artificial-induced continuously mixing on dissolved organic matter(DOM) removal performance, the variations of DOM concentrations, optical cha...     

An Experimental Study on the Treating River Sewage with New Bioreactor

A new bioreactor on the basis of a dynamic fluidized bed was designed, which combines advantages of the fluidized bed and a biological contactor. The experiments of start up, normal operation and parameter adjustment are carried out. The results show that the bioreactor can be quickly started up in the condition that the fill is 50%, the hydraulic retention time is 72 min, aerate speed is 2.5 m3/h, rotation-cage rotated speed is 1.5 r/min, and the removal rates of chemical oxygen demand （CODcr） and Ammonia nitrogen （NH3-N） are 75.34% and 80.98% respectively. The influence of the operation parameter on removal rates of the bioreactor is analyzed, and an appropriate operation parameter is provided.     

Ammonium-dependent regulation of aerobic methane-consuming bacteria in landfill cover soil by leachate irrigation

The impacts of landfill leachate irrigation on methane oxidation activities and methane-consuming bacteria populations were studied by incubation of landfill cover soils with leachate and (NH₄)₂SO₄ solution at different ammonium concentrations. The community structures and abundances of methane-oxidizing bacteria (MOB) and ammonia-oxidizing bacteria (AOB) were examined by PCRDGGE and real-time PCR. Compared with the pure (NH₄)₂SO₄ solution, leachate addition was found to have a positive effect on methane oxidation activity. In terms of the irrigation amount, ammonium in leachate was responsible for the actual inhibition of leachate. The extent of inhibitory effect mainly depended on its ammonium concentration. The suppression of the predominant methaneconsuming bacteria, type I MOB, was responsible for the decreased methane oxidation activity by ammonium inhibition. Methaneconsuming bacteria responded diversely in abundance to ammonium. The abundance of type I MOB decreased by fivefold; type II MOB showed stimulation response of fivefold magnification upon the first addition but lessened to be lower than the original level after the second addition; the amount of AOB was stimulated to increase for 20-30 times gradually. Accumulated nitrate from nitrification strengthened the ammonium inhibition on type I and type II MOB, as a result, repetitive irrigation was unfavorable for methane oxidation.     

氨对鱼类的毒性影响试验

早在本世纪上叶,国外学者就曾研究过氨对鱼类的毒性影响。1956年,Chipman 曾认为其毒性作用主要由 pH 值决定,NH_4~ 低毒或无毒。这一研究结果后来为 WuhrmannWoker(1948)、Merkeas(1955)及 Wilber(1971)等所证实。为了深入了解氨对鱼类及其它水生生物的毒性影响,我们于1980年—1982年,选择几种淡水鱼作为试验生物,分别研究了急性毒性,鱼类回避反应以及对呼吸率、肝体指数及血液酶活性的影响。     

鱼类对水污染回避反应的机制及实验装置

含毒工业废水引起鱼类的回避,这是鱼类对外界环境刺激的一种保护性反应。这种反应很敏感。使鱼类产生回避反应的化学物质,有时为现代化学分析仪器所不能胜任。尤其在自然条件下,水污染的成分往往十分复杂,难以用单一的理化指标所能表示其污染程度,但通过鱼类试验能够在一定程度上反映出水体的混合污染状况和污染的实     

英国渔业环保考察

英国环境问题,早在十八世纪就因煤烟污染而有黑国之称。随着工业发展,污染逐渐加重,水源供应不足。据英国供水工程学会资料:那时供应英格兰和威尔士的水,约占四分之一是受过污染的。但是,自六十年代以来,英国政府对环境问题开始重视,采取重大的改革和防治措施,使环境得到很大的改善,受到世界各国的好评。一、泰晤士河的治理经验泰晤士河是英国著名的河流。全长402公里,流域面积为一万三千平方公里。该流域的人口达1200万人,占英国总人口的四分之一。其中伦敦为800万人。这条河流横贯英国首都伦敦与十一个工业、文化城市