Plutonium isotopes concentration in seawater and bottom sediment off the Pacific coast of Aomori sea area during 1991-2005

A radioactivity survey was launched in 1991 to determine the background levels of ^239+240Pu in the marine environment off a commercial spent nuclear fuel reprocessing plant before full operation of the facility. Particular attention was focused on the ²⁴⁰Pu/²³⁹Pu atom ratio in seawater and bottom sediment to identify the origins of Pu isotopes. The concentration of ^239+240Pu was almost uniform in surface water, decreasing slowly over time. Conversely, the ^239+240Pu concentration varied markedly in the bottom water and was dependent upon the sampling point, with higher concentrations of ^239+240Pu observed in the bottom water sample at sampling points having greater depth. The ²⁴⁰Pu/²³⁹Pu atom ratio in the seawater and sediment samples was higher than that of global fallout Pu, and comparable with the data in the other sea area around Japan which has likely been affected by close-in fallout Pu originating from the Pacific Proving Grounds. The ²⁴⁰Pu/²³⁹Pu atom ratio in bottom sediment samples decreased with sea depth. The land-originated Pu is not considered as the reason of the increasing ^239+240Pu concentration and also decreasing the ²⁴⁰Pu/²³⁹Pu atom ratio with sea depth, and further study is required to clarify it.     

草地生态系统的生物地球化学循环

引言在一个生态系统内,如果没有遭受象耕种、生产农作物和施用肥料这样的周期性干扰,那么我们就把这个生态系统看成一个无干扰系统,象天然草地。由此也就利用这样有益环境,研究这种生态系统中包括N和P循环在内的许多过程的相互影响。对于热带生态系统,人们进行过上述研究,但可参阅的论文很少。目前的研究是要在印度占西(Jhansi)Aif Field牧场的Sehima村落对植物N和P的含量进行竹算。     

煤气化废水的生物除氮

对于经活性碳生物流化床处理去除有机物后的煤气化废水,采用硝化-反硝化处理系统和反硝化-硝化处理系统,进行了生物除氮试验研究。试验结果表明,必须添加甲醇作为反硝化处理过程的外来碳源,甲醇与NO_3~--N的最小投加比应为2.7:1。在适当的处理条件下,当进水NH_3-N为500毫克/升时,NH_3-N去除率可达98％,出水NH_3-N、NO_2~--N和NO_3~--N分别小于10、1和5毫克/升。     

美国的地震危险性

<正> 1 地震危险性评定历史早期地震建筑规范的技术要求是根据Algermieecn(1969)的初步工作——总结本国最大历史烈度,而Cornell(1968)的工作则是确立了对点源的概率地震危险性分析演绎法。该方法要求定义震源,震级分布和衰减函数,然后对所有可能的地震震级和距离进行积分来计算地震危险性。Merz和Cornell(1973),McGuire(1976,1978),Der Kiureghian和Aug(1977)将该方法推广到能包括非指数震级分布和断层源的研究。美国地质调查局也采纳了该演绎法,并将其应用到全国范围(Algermissen和Rerhins,1976),同时合并震源和最大震级的输入范围。McGuire(1974,1977)采用谱参数(而不是峰值运动参数)第一个示范了地震危险性方法。该方法以TAC—3(1987)模型建筑规范格式应用于全国。     

约旦的地震危险性

<正> 1 地震危险性评定历史约旦位于阿拉伯板块,它与长达1000km的死海地震活动带相邻,死海裂谷带为左旋走滑断层系。死海裂谷带为左旋滑动板块边界,起自亚喀巴湾东北,沿死海—约旦裂谷进入黎巴嫩中部直到叙利亚西北。过去曾发生过大地震(图1),图2表示1903～1983年仪器震中分布,1983～1992年由约旦地震台(JSO)记录到的地震如图3所示。自1983年以来,约旦建立了由26个地震台组成的台网,1990年又建了一个强震台网。1990年约旦出版了一部建筑规范,其中有一章为抗震设计规范。     

Bioproduction strategies for rare hexose sugars

A new strategy for the bioproduction of all ketohexoses was developed using hexitols as intermediates. Biocatalysts used to employ the strategy were D-tagatose 3-epimerase, which epimerizes ketohexoses at the C-3 position, and oxidoreductases, which catalyze oxidation-reduction reactions between ketohexoses and the corresponding hexitols. Arranging all the ketohexoses and hexitols in a symmetric ring and connecting them with 20 biochemical reactions, I was able to construct a design for the bioproduction of all the rare ketohexoses. Various aldose isomerases transform ketohexoses into the corresponding aldohexoses, so the strategy is useful for the bioproduction of all the rare hexose sugars. Furthermore, the design revealed that there are four routes to the L-hexose world from the D-hexose one.     

A research on dioxin generation from the industrial waste incineration

By using fluidized-bed furnace and rotary-kiln+stoker furnace and four different kinds of industrial wastes such as waste wood, coffee mill, waste oils and waste plastics, we have drawn the following conclusions:

(1) A relationship between H6CBz and DXN is acquired, which is DXN=0.34×H6CBz^1.1.

(2) The following means of emission reduction can be considered. (a) Reduction of DXN and Cl accumulation within the furnace, (b) control by the incinerated object, (c) control through the precursors of H6CBz, (d) improvement through operational control, (e) ammonia injection into the high-temperature zone of the furnace seems to be effective in reducing DXN and (f) DXN concentration is high with CO above 1800 ppm, though it decreases with CO below ≈10 ppm.     

C3-C14-alkyl nitrates in remote South Atlantic air

Alkyl nitrates with chain lengths up to fourteen carbons have been detected in the remote troposphere of the South Atlantic Ocean. The concentrations of numerous iso- and n-alkyl nitrates in the range of C3-C12 have been measured. Tenax-GC analysis was applied to determine short chain alkyl nitrates (< C6), while the novel detection of long chain iso- and n-alkyl nitrates was achieved with a high volume sampling technique using silica gel. C3-C12-alkyl nitrates show the lowest concentrations in the trade wind region (3.5 pptv). Higher concentrations in the west wind belt (11.1 pptv) reveal the influence of the South American continent as the source for the alkyl nitrates after long range transport. The concentrations of alkyl nitrates increase in proximity to South America. Measurements of long chain alkyl nitrates in rural air near the city of Ulm (Germany) are given for comparison. In addition, pattern analysis of long chain alkyl nitrates reveal this complex mixture of new compounds to be useful as trace indicators to distinguish continental and marine air masses. Despite the lower photochemical formation yields of primary n-alkyl nitrates compared to secondary n-alkyl nitrates, the primary n-alkyl nitrates are relatively increased in marine air. The reason for this finding cannot be explained so far, but the correlation of secondary/primary n-alkyl nitrates shows a significant differentiation of air samples with continental or marine character.