湖南早前寒武纪变质结晶基底的Sm-Nd同位素年龄

出露在湘东北益阳一浏阳，呈近东西向断续分布，经角闪岩相一绿片岩相变质结晶片岩、层状、似层状超镁铁质岩的sm—Nd全岩等时线年龄为2．6—3．028Ga、2．2—1．9Ga，应属湖南早前寒纪结晶基底岩片。     

长江中下游地区变质基底及地壳形成时间

本文根据长江中下游地区中生代侵入岩长石Pb同位素组成和Nd同位素模式年龄研究，提出长江中下游地区是由几个晚太古-早元古代和中元古代块体组成的变质基底；其地壳的形成具有多阶段演化的特点，大致是：晚太古代（＞2500Ma）形成古陆核，早元古代（2500－1900Ma）陆壳初步形成，中元古代（1800－1200Ma）陆壳快速增长，晚元古代（1000Ma）以后区内陆壳增生基本趋于停止。     

Aquifer Transmissivity and Basement Structure Determination Using Resistivity Sounding at Jos Plateau State Nigeria

A geoelectric investigation involving twenty-six vertical electrical soundings was carried out at Jos, Plateau State, North Central Nigeria. The survey was aimed at determining the structure of the underlying bedrock, as well as computing the transmissivity for the aquifer in the area. The basement geometrymapproduced from the results of the survey indicates that the bedrock is undulating lying at depths between 30 m to 6.5 m. There is evidence of faulting and fracturing within the area. Computation of aquifer transmissivity values based on the results obtained made it possible to demarcate regions with good ground water potential in the area.     

GROUND WATER YIELDS AND INVENTORY FOR LAND-USE PLANNING IN CRYSTALLINE ROCK AREAS OF WAKE COUNTY,NORTH CAROLINA1

In urbanizing areas underlain by crystalline rocks an inventory of the usable ground water should form an important element in the land-use planning process. Land-use decisions are most often made upon water-well yield data alone, but these data do not address the inventory question. A method utilizing local geology, stream lowflow characteristics, and pumping test data permitted outlining portions of Wake County, North Carolina, which are more favorable and those which are less favorable for ground water supply development. Information from state-required 24-hour pumping tests on 232 wells was supplemented by information from an additional 100 wells whose initial yields were determined by shorter pumping tests. Comparison of the ground water inventory values on a per acre or per square mile basis with average water use at various residential densities provides information useful to the responsible political body as it decides about population density distribution and the need for surface water supplies. For Wake Country an average density of one residential unit per acre appears generally permissible before overdraft of the ground water supplies becomes a significant risk. By utilizing the ground water inventory and patterns of ground water yields from various rock types, county officials can maximize the effectiveness of public facilities funds. The technique appears useful for other parts of the Piedmont region of the southeastern United States.     

影响经济与环境协调发展的经济根源

环境污染作为一种经济行为,必然受到经济运行规律的制约,它的产生有着深刻的经济根源。影响经济环境协调的因素有市场失效、政策失效等。市场在分配和有效利用环境资源上失效,使得政府通过经济政策进行干预成为必要,但政府政策有强化环境资源市场失真而非纠正的趋势。只有采取各项政策和手段的组合运用才可能促进经济与环境持续发展。     

Effect of Crystalline and Amorphous Structures on Biodegradability of Poly(Tetramethylene Succinate)

The effect of orientation in the amorphous and crystalline regions on the biodegradability of PTMS [poly(tetramethylene succinate)] was studied using the amorphous orientation function, birefringence, and crystallinity. The crystalline and amorphous intrinsic lateral sonic moduli, E _t,c ⁰ and E _t,am ⁰ , were 2.61 × 10³ and 0.41 × 10³ MPa, respectively. Using the data on birefringence, crystalline and amorphous orientation function (f and f _am), crystallinity, and sonic modulus of the oriented PTMS fibers, the intrinsic birefringence of the crystalline ( _c ⁰ ) and amorphous ( _am ⁰ ) regions were evaluated to be 0.0561 and 0.0634, respectively. The biodegradabilities of oriented PTMS films were reduced as the elongation increased, i.e., the amorphous orientation increased. At low elongation (100 and 150%), however, biodegradabilities remained unchanged when the degradation test was performed in activated sludge, which was attributed to the amorphous orientation occurring even at 100% elongation, though the amorphous orientation direction was perpendicular to the fiber axis.