川西前陆盆地流体的跨层流动

本文讨论了川西前陆盆地气田区上三叠统和侏罗系地层水K+ +Na+ 、Ca2 + 、Mg2 + 、Br-与Cl-离子、矿物 (胶结物和充填物 )碳氧同位素和水的氢氧同位素成分组成以及相互关系。气田区上三叠统流体来源以地层海陆相沉积物质为主 ,并与渗流水混合 ,形成“下部流体”。有气藏的侏罗系内流体 (称“上部流体”)与“下部流体”的水化学和同位素组成相近 ,且具有同一演化趋势 ,表明它来源于下部流体并与侏罗系层内的渗流水发生过混合作用。本文提出该气田流体具跨层流动、二次混合演化特征 ,认为大规模的流体对流混合促进了上三叠统内天然气的运移聚积 ,在三叠系内有利构造圈闭中形成原生或残留气藏并向上运移 ,在侏罗系内有利圈闭中形成“次生”气藏。     

青藏高原东北部气候变化的异质性及其成因

利用1961-2016年西宁等青藏高原东北部13个气象台站气温、降水等气象资料以及国家气候中心发布的南海季风指数、西伯利亚高压指数等大气环流特征量数据,分析近56年来气候变化与高原主体的差异性及其可能的气候成因。研究表明：近56年来青藏高原东北部气候变暖趋势十分显著,年平均气温气候倾向率高达0.39 ℃/10 a,呈现出三次明显的阶梯性增高态势,并于1994年前后发生了由冷到暖的突变,同时具有明显的空间差异性;年降水量及四季降水量均没有明显变化趋势,虽然经历了2002年左右由少到多的变化,但并未出现明显突变,年降水量具有3年、5年的准周期,而年降水日数微弱减少,降水强度呈增加趋势;该区域气候变化的年际波动主要受到东亚季风、高原季风和南海季风的年际振荡及其相互作用的影响,而西风环流的作用并不明显,植被覆盖的恢复既是对2002年以来降水量增加的具体反应,同时也对于气候变暖趋势起到了一定的缓和作用。     

“中国南方喀斯特”世界自然遗产申报战略研究

中国南方喀斯特地区面积大,自然资源丰富,生态环境脆弱,在世界喀斯特地区中极具代表性。文章依据中国南方喀斯特地区独特的自然特征和社会、经济功能,借助申报自然遗产机遇,为实现该区人口、资源、环境与社会的可持续发展,提出了一系列针对中国南方喀斯特地区的保护策略及措施。     

中国南方工业开发策略

根据已有工业基础及其资源开发环境因素,以及国内外经济发展态势,为实现中长期工业实力达到与其人口规模相适应的战略目标,中国南方工业开发应以市场为导向,以效益型经济为核心,以技术进步与产业结构调整为基础,建立内外向结合型工业结构;实行以轻型工业为主导部门,以基础工业为整体工业的推进部门的产业倾斜策略,和以沿海、沿江、沿铁路干线为主轴线,以大中城市(含沿海港口开发区)为极点的点轴开发的非均衡发展策略;强化地域间、产业或部门间的分工与协作,推进包括原料-加工中心在内的工业综合体的开发模式,形成面向国内外市场的优势产业与地方性产业等多层次、不同类型的综合工业基地,以求振兴全区工业,井增强其在全国经济中应有的地位。     

川西南阿什及尔期地层中的Ce异常及其古海洋学意义

川西南阿什及尔期地层中的全岩REE分配模式显示 ,含有浮游笔石和小型无铰纲腕足类的黑色页岩具有较低的Ce异常值 (0 .6 2～ 0 .74) ,而含有底栖三叶虫、有铰纲腕足类和藻类的非黑色页岩则具有较高的Ce异常值 (0 .92～ 1.30 )。Ce与其他元素的相关分析进一步揭示 ,Ce与Fe的相关性最好 (r =0 .85 ) ,与P的相关性次之 (r =0 .6 1) ,与Al的相关性较差 (r =0 .2 9) ,而与Mn和Ca几乎不相关 (r =0 .14,r =- 0 .0 2 )。实际观察可能表明 ,研究区底层水体在氧化和碱性条件下 ,Ce氧化为Ce4 + 并进入Fe的氢氧化物和磷酸盐的晶格中 ,或者被吸附到它们的表面 ,造成Ce在氧化水体中呈现负异常而在同期氧化沉积物中呈现正异常或负异常不明显 ;相反 ,在还原和酸性条件下 ,Ce在水体中以 +3价状态富集 ,引起Ce在同期缺氧沉积物中呈现明显负异常。作为古海水氧化还原指示的全岩Ce异常 ,通常限定于解释远洋细粒沉积物的沉积环境。我们的研究结果说明 ,移去化石骨骼 (通常是磷酸盐化石骨骼 )的浅海细粒沉积物同样可以用于全岩REE分析 ,以获得可靠的能够指示古海水氧化还原条件变化的Ce异常     

四川人地关系日趋紧张的原因及对策

本文分四个阶段分析了四川人地关系的变化情况及人地关系的现状；以量化的方式重点分析了四川人地关系变化的原因；简要分析了人地关系的变化给农业生产所带来的影响；针对人地关系变化的主要原因,提出了缓解人地矛盾的对策。本文的重点是对四川人地关系变化原因,尤其是近期人地关系变化原因的分析,其目的是让人们认识近期四川人地关系变化的主要原因,以对症下药,采取有效的措施,缓解四川的人地矛盾。     

南水北调中线水源区浮游植物与水质研究

2003~2005年对南水北调中线水源区水体浮游植物的调查结果表明,该水域共有浮游植物96种及变种,隶属于8门63属,其中种类最多的藻类植物依次是硅藻、绿藻和蓝藻.藻类的细胞密度表现出夏季最高、冬季最低的明显季节变化.运用Margalef和Menkinick多样性指数对该水域的水质进行评价,结果显示,水体为寡污型,基本处于中营养状态.图3表3参14     

川中半自然型防护林演替过程中的物种多样性

四川中部绵阳官司河流域的半自然型林是长江中上游地区防护林的一个较典型类型。本文以它为研究对象，对群落的物种多样性及其在次生演替过程中的动态变化趋势进行了初步研究，并结合影响多样性的几个主要环境因子进行了相关性分析。结果表明：（1）现阶段该防护林的植物种类组成和群落结构均较简单，松、柏、栎混交的针阔叶林占绝对优势，其物种多样性较小，但随着群落次生演替的进展，各层次的多样性趋于增加；（2）用灰色系统理论的关联度分析方法研究群落的物种多样性与主要环境因子的相关性是可行的。经测定，研究区的土壤pH值，外界干扰度和土壤含水量等指标对防护林的物种多样性有显著的影响。图2表3参16     

Response of Savanna Fire Regimes to Changing Fire-Management Policies in a Large African National Park

Abstract:  Approaches to fire management in the savanna ecosystems of the 2-million ha Kruger National Park, South Africa, have changed several times over the past six decades. These approaches have included regular and flexible prescribed burning on fixed areas and a policy that sought to establish a lightning-dominated fire regime. We sought to establish whether changes in management induced the desired variability in fire regimes over a large area. We used a spatial database of information on all fires in the park between 1957 and 2002 to determine elements of the fire regime associated with each management policy. The area that burned in any given year was independent of the management approach and was strongly related to rainfall (and therefore grass fuels) in the preceding 2 years. On the other hand, management did affect the spatial heterogeneity of fires and their seasonal distribution. Heterogeneity was higher at all scales during the era of prescribed burning, compared with the lightning-fire interval. The lightning-fire interval also resulted in a greater proportion (72% vs. 38%) of the area burning in the dry season. Mean fire-return intervals varied between 5.6 and 7.3 years, and variability in fire-return intervals was strongly influenced by the sequencing of annual rainfall rather than by management. The attempt at creating a lightning-dominated fire regime failed because most fires were ignited by humans, and the policy has been replaced by a more pragmatic approach that combines flexible prescribed burning with lightning-ignited fires.     

High genetic diversity of the symbiotic dinoflagellates in the coral Pocillopora meandrina from the South Pacific

Symbioses between dinoflagellates in the genus Symbiodinium (commonly referred to as zooxanthellae) and scleractinian corals are an essential feature for the maintenance of coral reefs. The fine-scale diversity and population structure of the zooxanthellae inhabiting the coral Pocillopora meandrina, a major reef building species in Polynesia, was examined. We used two polymorphic microsatellites to study seven populations from the South Pacific, whose host structuring has been previously investigated. The symbionts of P. meandrina showed high levels of diversity, with more than one zooxanthella genotype being identified in most of the host individuals. Genetic differentiation between symbiont populations was detected at a large scale (2,000 km) between the Tonga and the Society Archipelagos. Within the Society Archipelago, the two most remote populations (Tahiti and Bora-Bora; 200 km apart) were only weakly differentiated from each other. Statistical tests demonstrated that the symbiont genetic structure was not correlated with that of its host, suggesting that dispersal of the symbionts, whether they are transported within a host larva or free in the water, depends mainly on distance and water currents. In addition, the data suggests that hosts may acquire new symbionts after maternal transmission, possibly following a disturbance event. Lastly, the weak differentiation between symbiont populations of P. verrucosa and P. meandrina, both from Moorea, indicated that there was some host-symbiont fine-scale specificity detectable at the genetic resolution offered by microsatellites.