Differential predator escape performance contributes to a latitudinal sex ratio cline in a migratory shorebird

Sexual segregation outside the mating season is common in vertebrates, and has been attributed to sexual differences in predator escape performance in ungulates and fish, but not in birds. Here, we tested the hypothesis that sex- and latitude-specific predator escape performance underlies the differential nonbreeding distribution of western sandpipers (Calidris mauri), a migratory shorebird. Females overwinter further south along the American Pacific coast, creating a latitudinal cline in sex ratio. Escape performance is reduced with increasing body mass, and birds generally carry less fat further south. Western sandpipers with poor escape performance were therefore predicted to prefer southern sites to reduce the risk of mortality posed by predators. Data from four nonbreeding latitudes showed that wing loading, used as an index of escape performance, was overall higher for females, and that it decreased with latitude in both sexes. Within latitudes, wing loading was lower at smaller, and presumably more dangerous, sites. Flight response to a predatory attack was longer in the south. Mortality risk offers a novel and candidate explanation for differential distribution patterns in western sandpipers and possibly other avian migrants.     

THE EFFECTS OF DEICING SALTS ON WATER CHEMISTRY IN PINHOOK BOG,INDIANA1

ABSTRACT: A five-year study was conducted to identify the effects of road salt intrusion on the water chemistry of Pinhook Bog following operation of an uncovered salt storage pile adjacent to the bog for ten years. A distinct pattern of elevated salt concentrations was observed in the interstitial waters of the surface peat that corresponded to observed alterations in the bog vegetation. Yearly mean salt concentrations as high as 468 mg/l sodium and 1215 mg/l chloride were recorded in the plant root zone of the peat mat. The salt concentrations decreased significantly each year from 1979 to 1981 throughout the impacted area. Some increases of a lesser magnitude occurred in 1982 and 1983. Analysis of salt movements suggested that vertical transport by water movement was responsible for concentration changes. The major declines in salt levels occurred in the spring following snowmelt and heavy precipitation events. Evapotranspiration during periods of drought resulted in the gradual increases in surface peat salt concentrations. Diverted highway runoff was shown to be the major continuing source of sodium chloride contamination and was the likely source of the elevated calcium, magnesium, potassium, bicarbonate, and pH levels also observed in the impacted area.     

有关1556年关中大地震几个问题的探讨

本文讨论了1556年关中大地震震中位置、震级和人口伤亡等几个问题。认为震中应在潼关、蒲州之间,震级高于8级,人口伤亡数字无夸大的可能。     

URBANIZATION AND STREAM QUALITY IMPAIRMENT1

ABSTRACT: A study was conducted in the Piedmont province of Maryland to determine if a relationship exists between stream quality and the extent of watershed urbanization. During the first phase of the study 27 small watersheds, having similar characteristics but varied according to land use, were investigated. Using these controlled conditions, eliminating as many interferences as possible, this first phase was intended to determine if a definite relationship did exist between the two factors. Finding that the first phase was successful the second was initiated which consisted of a comparison of biological sampling data, from other studies, with degree of watershed urbanization. The purpose of this second phase was to ascertain if the relationship between degrees of urbanization and decline in stream quality was linear as watershed area increased and in streams spread throughout the Maryland Piedmont. The principal finding of this study was that stream quality impairment is first evidenced when watershed imperviousness reaches 12%, but does not become severe until imperviousness reaches 30%.     

垃圾焚烧重金属迁移特性及其影响因素

综述了城市固体垃圾(MSW)焚烧过程中的Hg、Cd、Pb、Cu、Zn、As和Cr等几种主要重金属污染源在焚烧过程中的迁移特性及其主要影响因素。将重金属在焚烧过程中的迁变归结为:蒸发、气相和表面反应、冷凝成核团聚和飞灰吸附等4个主要过程;而垃圾中重金属的初始浓度、原始垃圾的基体盐分(如A l、S i和K、Na等的存在形式)、垃圾中的C l(PVC和NaC l)和S的含量、垃圾的含水量以及焚烧过程中的运行参数(温度、滞留时间、氧化-还原气氛)等都会对焚烧过程的迁移规律产生影响。     

超重力旋转填料床在燃煤尾气处理上的应用进展

本文指出了我国燃煤尾气脱硫进展缓慢的原因 ,介绍了一种新型的燃煤尾气脱硫设备———超重力旋转脱硫床的工作原理、传质特性及在低浓度的废气处理上的广阔应用前景     

黄土性土壤对砷的净化作用及迁移规律研究

通过土柱淋滤试验,从动态角度研究了黄土性土壤对砷的净化作用及迁移规律。研究结果表明,黄土性土壤对砷是一次性的吸附净化并达到饱和状态。土壤对砷净化吸附分为3个阶段:全吸附段、部分吸附段和吸附饱和段。受土壤粘粒和钙影响,黄土性土壤中砷运移的速度不同,其顺序为v(粘化层)相似文献   

Orientation in captive migratory and sedentary Australian silvereyes <Emphasis Type="Italic">Zosterops lateralis</Emphasis> (Zosteropidae)

The orientation of two closely related subspecies of Australian silvereye Zosterops lateralis was studied in captivity over 14 months. Migratory silvereyes Z. lateralis lateralis showed significant directional preferences during the spring and autumn migration periods and also displayed orientated behaviour during the breeding period. In contrast, the non-migratory subspecies Z. lateralis familiaris did not display any significant directional preferences at any time. This is the first time that the orientation behaviour of a migratory and non-migratory subspecies has been compared over the duration of an annual cycle, both during and outside the migratory periods. The results suggest that migratory silvereyes possess an endogenous program determining the timing and direction of autumn and spring migration and that this program is unique to the migratory subspecies. This is also the first comparison of this nature on southern hemisphere birds and demonstrates that the migratory behaviour of southern hemisphere migrants may be more similar to that of northern hemisphere migrants than previously thought.Submitted to Behavioral Ecology and Sociobiology: 23 Jan 2006.     

Modelling asymmetrically distributed circular data using the wrapped skew-normal distribution

We consider problems of inference for the wrapped skew-normal distribution on the circle. A centered parametrization of the distribution is introduced, and simulation used to compare the performance of method of moments and maximum likelihood estimation for its parameters. Maximum likelihood estimation is shown, in general, to be superior. The operating characteristics of two moment based tests, for wrapped normal and wrapped half-normal parent populations, respectively, are also explored. The former test is easy to apply, maintains the nominal significance level well and is generally highly powerful. The latter test does not hold the nominal significance level so well, although it is very powerful against negatively skew alternatives. Likelihood based tests for the two distributions are also discussed. A real data set from the ornithological literature is used to illustrate the application of the developed methodology and its extension to finite mixture modelling. Received: September 2003/ Revised: April 2005     

加油站泄漏污染物的迁移分布规律

选择某废弃加油站场地为研究对象,通过采集分析土壤和地下水样品中的铅（Pb）、总石油烃（TPH）、多环芳烃（PAHs）、苯系物（BTEX）、甲基叔丁基醚（MTBE）,分析了污染物在该区域地下环境中的迁移和分布特征.测试结果表明：场地包气带和含水层介质岩性以砂质粉土、粘质粉土和粉质粘土为主,土壤样品中总石油烃（C < 16）和苯均存在超标现象;垂向污染物高浓度值多出现在地下水面附近,其中上层滞水区总石油烃和苯大面积超标,潜水中总石油烃（C < 16）、苯及MTBE超标,承压水尚未被污染.在分析目前石油类污染场地修复技术的基础上,结合场地的实际条件,建议土壤和地下水的修复主要采用异位修复技术.