贵州遵义牛蹄塘组黑色岩系的硒同位素变化及其环境指示初探

西南早寒武世牛蹄塘组是分布在中国南方扬子地台的一套黑色岩系,区域上发育有典型富集多金属元素的硫化物矿化层.选取遵义松林小竹牛蹄塘组下部富硒、钼、镍等元素的黑色岩系剖面,利用Se同位素初步探讨了该剖面岩石的沉积环境和硒的可能来源.结果表明,小竹牛蹄塘组下部剖面黑色岩系的δ82/76SeSRM3149比值变化较大,下部底层含碳斑脱岩与磷块岩的变化范围在-4.35‰～ 4.11‰之间;中间镍钼层及碳质页岩、碳质碳酸盐岩的δ82/76SeSRM3149变化范围窄,平均值为0.9‰±0.23‰(n=4);上层碳质页岩为-1.24‰.结合已发表的钼同位素数据,认为中间岩石沉积于缺氧/无氧环境,但存在盆地海水与热液或充氧水团的混合;下层的岩石曾一度位于充氧与贫氧环境的边界面,局部岩石曾暴露地表经历了较强的风化和蚀变作用,海水中硒有可能来自底部富硒斑脱岩的氧化淋滤或海底热液.据此推测遵义松林小竹牛蹄塘组下部岩石的沉积环境极可能处在局限盆地靠近陆地的边缘部分,经历了充氧→贫氧→缺氧/无氧→贫氧的演化阶段.     

胶东-朝鲜半岛中朝扬子碰撞带初析

根据对胶东半岛北缘的栖霞陡崖剖面、胶莱盆地南缘的诸城皇华店剖面以及朝鲜半岛临津江群的野外露头地层、古生物、岩性等特征的研究,推论中朝与扬子碰撞带的南部界线位于皇华店至朝鲜军事分界线之南。     

SEDIMENT DAMAGES AND RECENT TRENDS IN THE UNITED STATES

lINTRODUCTIONWeoftenhavethepercepti0nthatsedimentisthebr0wnishoryell0wishcoloringinrunoffwater,thatlooksunpleasant,buteventually"g0esaway,"downstream,unseen.Butsedimentisn0tonlyaestheticallyunpleasant,itisalsoacarrierofpotentialchemicalc0ntaminants,fillsupwaterb0dies,andcausesphysicaldamaget0farmland,wildlife,andwatertreatmentsystemsandpowergenefat0rs.ThepurposeofthispaPeristoprovidean0verallperspectiveonthemagnitudeandtrendsofsedimelltasap0llutritintheUnitedStates.2CURRENTKNOWLEDG…     

The ethics of population control in rural China, 1979-92

This article identifies some issues of importance in understanding China's policy of population control. This article presents evidence of trends in fertility, population policy, family planning, and socioeconomic change; and then discusses the conflict between fertility preferences and policy that is evident from studies of ideal family size and sex ratios. Some issues that are identified as "uncertain" include the extent of spread of family planning service delivery and its associated insurance schemes, local family planning policies and cadre responsibility systems, the demand for children, the demand for female children, the economic and environmental consequences of population growth, the fairness of reproductive restrictions and their application, and the extent of coercion in the later-longer-fewer policy era. It is argued that an ethical framework for analyzing China's population policy should include answers to questions about the harm to welfare from population growth, the government's right to demand voluntary reproductive sacrifice or to impose demographic or reproductive restrictions and punishment, and the government's right to impose coercion. If it is accepted that population growth in China has adverse consequences and its control would be beneficial to all, then it must be determined what the nature of the relationship should be between the state and the individual. The author refers to Walzer's (1983) position that the legitimacy of Chinese state power depends in part on whether political leaders at all levels are competent and not corrupt. The rights and duties of the government and individuals must be understood not just in terms of political legitimacy but also in terms of social justice. Social justice is dependent upon the degree of horizontal and vertical consultation and accountability, utilitarian consequences, and protected spheres of individual judgement. Utilitarian theories justify the one-child policy, while deontological theories support reproductive freedom as an absolute right.     

南非于2004年5月颁布新矿业法

南非矿产和能源部长PhumzileMlambo Ngcuka女士在开普敦召开的非洲矿业投资大会上说 ,倍受争议的南非新矿业法———《矿产和石油资源开发法》计划于 ( 2 0 0 4年 ) 5月颁布。Mlambo Ngcuka部长谈到了新矿业法中的关键举措之一 :“由于历史原因而处于劣势的南非人”(HDSA)要在     

多区域海洋M3分潮的观测与验证

M₃海洋分潮(三阶潮或一日三次周期潮汐)经常受到忽视,因而对M₃分潮进行更精确的分析研究,可以提高潮汐预测、海洋数值模拟、大地测量的准确度.尽管M₃分潮在整体潮汐所占比例较小,但由于陆架共振及其他影响,某些沿海地区M₃潮可大大增强.本文使用157个验潮站的数据,以及9年时间窗口,对水位变化进行了潮汐谐波分析.本文还分析了太阴M₃潮,将这些结果与全球同化的模型数据(TPXO9v5a)进行了比较,重点研究了西太平洋和欧洲陆架地区.与验潮站数据相比,大部分区域TPXO9v5a导出的M₃潮振幅和相位滞后表现良好,但在沿海和地形复杂的区域,其结果误差较大.在欧洲陆架海域使用了一个浅水数值模型(MARS),该模型在某些地区优于TPXO的结果.在欧洲陆架海域的五个子区域中, TPXO在三个地点的M₃振幅及相位滞后预测的均方根误差(RMSE)更小.而在其他子区域, MARS模拟结果更为准确.本文发现一些地点的M₃振幅有着显著长周...     

A grain-size correction for metal pollution indexes in river sediments

According to the List of Hazardous Substances of the Agency of the Toxic Substances and Disease Registry(ATSDR 2017),some metallic elements such as Pb or Cd are still considered as the most polluting elements in the world.These elements accumulate in sediments,and there are various methods available that differentiate lithogenic sources from anthropogenic sources.For that,the natural geochemical background is required,however,its definition is far from unanimous:it can be a global or local value,single or statistically estimated value,depending on the studies.Our study is focused on the Suba
e River in the state of Bahia,Northeastern Brazil,which was historically contaminated by lead metallurgy.The river sediments were sampled at 21 locations:one at the discharge point of the plant's rainwater basin,ten upstream,and ten downstream.The total contents of Fe,Ti,Mn,Pb,Zn,Cu,Cr,particle-size distribution,and organic matter were analyzed.The conventional geochemical indexes,i.e.,the pollution degree(mCd),pollution load index,and enrichment factor indicated contamination by Zn,Pb,Cr,and Cu.Then,a new enrichment factor is introduced,assuming that the sediments come from erosion of soils in the watershed.After obtaining the natural concentrations of metals in the clay,silt,and sand fractions of uncontaminated reference soils,we corrected the pollution indexes by calculating a new individual background in each sediment sample,according to its grain size distribution.This new approach provided more precise indexes in the assessment of sediment pollution,by highlighting higher contamination of Zn and Pb(around 50%)and at the same time the absence of Cr and Cu contamination,two metals not involved with the metallurgical activity.     

Multi-scale distribution and dynamics of bivalve larvae in a deep atoll lagoon (Ahe, French Polynesia)

Bivalve larvae and hydrographic parameters were sampled over a range of spatio-temporal scales in a deep atoll lagoon. Bivalve larvae abundances were very high throughout the year: 18,550 m(-3) in average. Larvae were (i) concentrated at mid-depth with nocturnal ascent and diurnal descent, (ii) heterogeneously dispersed at the lagoon scale, (iii) subject to day-to-day variation in abundance and (iv) transferred between different parts of the lagoon providing evidence of intra-lagoonal connectivity. The primacy of physical factors was seen on large spatial scale with the diluting effect of water renewal and transfers by hydrodynamics. On smaller spatial scale, the primacy of biological processes was recognised, with larval swimming activity leading to dial vertical migration correlated with food concentration. Variations in larval abundance were driven by bivalve reproductive activity correlated with meteorological conditions (i.e. windy periods). Finally, relationship between bivalve larvae patterns and pearl oyster (Pinctada margaritifera) settlement structuring is discussed.     

Atmospheric Corrections Using MODTRAN for TOA and Surface BRDF Characteristics from High Resolution Spectroradiometric/ Angular Measurements from a Helicopter Platform

l. IntroductionThe cIassicaI definition of bi--directional reflectance--distribution function (BRDF) is aderivative, distribution function, relatlng the irradiance incident from one given direction tolts contribution to the radiance renected in another direct1on (N1codemus et al., l977).f r (0,, rp,; 0,, rp, )= dL, (0,, P,; 0,, 9,; E, )/ dE, (0,, 9,) [sr-- 1 ], (l)where 0 (zenith angle) and 9 (azimuth angle) together indicate a direction, the subscr1pt i indi-cates quantities associated wi…