石油地化中测定痕量元素的仪器中子活化分析法与感应耦合等离子体…

本文对测定原油、石油馏分和源岩沥青中痕量元素的ＩＮＡＡ法与ＩＣＰ－ＭＳ法进行了比较。多种原油测定结果表明，对许多有重要地球化学意义的元素，两种方法都能测定，且测定结果有良好的一致性。对于另外一些元素两种方法可互为补充。本文还对地化勘探程序中的ＩＮＡＡ和ＩＣＰ－ＭＳ法的优缺点进行了比较，并举出了应用实例。     

夏初雨多旱象缓 盛夏无雨伏旱重

1989年是我省继1987 1988连续两年干旱的又一大旱之年沈阳地区遭到百年未遇旱灾。其他地区旱情也是建国以来所少见的由于长期持续高温少雨,全省相继发生大范围的伏旱和“秋吊”,导致我省农业全面严重受灾。据有关部门统计,全省粮豆作物受灾面积达3800万亩,受旱果树7070万株。     

The Orbital Period of the Be/Neutron Star Binary RX J0812.4-3114

We present the results of Rossi X-Ray Timing Explorer (RXTE) observations of the Be star X-ray binary system RX J0812.4-3114. A light curve obtained with the RXTE All-Sky Monitor (ASM) shows that the source is currently in an active state with outbursts occurring at approximately 80 day intervals. The source underwent a transition from an inactive state to this regular outburst state early in 1998. An observation of RX J0812.4-3114 was obtained with the RXTE Proportional Counter Array (PCA) close to the time of a predicted maximum in 1999 March, and strong pulsations were detected at a period of 31.88 s. This confirms the result of an earlier PCA observation by Reig & Roche that was also obtained serendipitously near the predicted maximum flux of the 80 day period and also near the start of the current active state. We interpret the periodicity in the ASM light curve as indicating the orbital period of RX J0812.4-3114 with outbursts occurring around periastron passage.     

Achieving environmentally relevant organochlorine pesticide concentrations in eggs through maternal exposure in Alligator mississippiensis

Alligator mississippiensis eggs from organochlorine pesticide (OCP) contaminated sites in Florida exhibit high rates of embryonic mortality compared to reference sites (P < 0.05). The objective of the present study was to use captive adult alligators to test the hypotheses that maternal exposure to OCPs results in increased OCP concentrations in eggs, and that increased exposure is associated with increased embryonic mortality. A total of 24 adult alligators (8 males and 16 females) were housed in eight pens. Eight females in four pens were dosed with a mixture of p,p'-DDE, toxaphene, dieldrin, and chlordane at a rate of 0.2+/-0.01 mg/kg/day for 274+/-8 days. Treated females produced eggs containing higher OCP concentrations (12,814+/-813 ng/g yolk) than controls (38+/-4 ng/g yolk). Eggs of treated females exhibited decreased viability (13+/-22%) as compared to controls (45+/-20%). Results indicated that 0.6% of administered OCPs were maternally transferred to the eggs of American alligators, and that maternal exposure is associated with decreased egg/embryo viability in this species.     

Economics of transboundary aquifer management

This paper presents a general model of optimal water management for a transboundary aquifer under three different management approaches: cooperative, noncooperative, and myopic. Comparing the results from the approaches, we find the cooperative solution, where a single management plan is executed for all parts of the aquifer, results in the highest level of net social welfare, followed by the noncooperative and then the myopic. The trade-offs we find for the higher levels of welfare are lower use levels in the earlier periods. We present a short discussion of factors that can increase the inefficiencies of the models and suggest directions for future research.     

火山侵蚀和塌陷——以侵入体为中心的矿床叠生的成因

叠生作用是早期深部斑岩型矿化与晚期浅部贵金属和贱金属低温热液型矿化并置和叠覆的过程，叠生作用被认为是由于火山机制在洪积条件下受到迅速侵蚀或扇形（及不太可能的在皮火山口）塌陷引起的火山古地表同热液剥蚀造成的，在热液系统１Ｍａ的时间间隔内，古地表可下降１ｋｍ，使所含各类矿床至少在７ｋｍ的垂向范围内密集，由同矿化侵入作用造成的火山膨胀可以引发扇形塌陷，而火山机构的水热活动减弱使塌陷更容易。扇形塌陷引起大