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911.
基于深地勘探的化探新方法发展现状分析   总被引:1,自引:0,他引:1  
矿产资源是人类社会经济发展的重要物质基础,我国目前处于经济大发展时期,对矿产资源的需求量日益增大。然而随着已知矿、露头矿及浅部矿的日渐枯竭,未来的勘探工作重点势必将由地表浅部转向地下深部的隐伏矿勘查。国内外找矿实践证明,化探在寻找深部及隐伏矿床方面是一种直接、快速、有效的方法技术,而且随着"深穿透地球化学"概念的提出及发展,通过对穿透能力很强的气体、纳米级微粒、离子提取技术和植物地球化学测量技术的研究,提出了相关的深穿透地球化学勘探方法技术,本文对其异常形成机制进行了分析,并就其在寻找深部及隐伏矿床中的成效进行了探讨。  相似文献   
912.
拉萨河源头水域中浮游生物、鱼类资源调查与分析   总被引:1,自引:0,他引:1  
拉萨河是西藏重要的河流之一,流经多个县市,拉萨河的生态性调查和环境保护对西藏的社会和经济发展重要意义。本调查在拉萨河上游11个乡镇分别进行断面取点调查,对各乡镇境内拉萨河段进行浮游生物与鱼类取样统计分析。本次调查中,共检出浮游植物76个种类,其中硅藻门48种,占总种类数的63.2%;绿藻门12种,占总种类数的15.8%;蓝藻门6种,占总种类数的7.9%;金藻门4种,占总种类数的5.3%;隐藻门3种,占总种类数的3.9%;黄藻门和裸藻门各1种,分别占总种类数的1.3%;共检出浮游动物4大类50种,其中原生动物24种,占总种数的48%;轮虫12种,占总种数的24%;枝角类10种,占总种数的20%;桡足类4种,占总种数的8%;共发现1目2科5属的鱼类5种,均为鲤形目,本地鱼类有3种,占总数的60%,外来种有2种,占到总数的40%,其中拉萨裸裂尻鱼(Schizopygopsis younghusbandi Regan)和双须叶须鱼[Ptychobarbus dipogon(Regan)]为雅鲁藏布江特有鱼类。本次调查采集到的外来鱼种有棒花鱼和鳅鱼两种。经本次调查,西藏拉萨河源头流域,生物多样性略贫乏,尤其是鱼类种类较少。而鱼类保护工作面临的两大挑战就是外来鱼种入侵以及过度捕捞而造成的鱼类资源减少。  相似文献   
913.
The sea star Asterina stellifera has declined during the last decade and is currently abundant only in the southern limit of its former range. We surveyed this population over 5 years to model individual growth and explore the relationship of changes in local abundance with variation in environmental factors and the reproductive status of individuals. Our results show that A. stellifera is a species with slow growth and a relatively long lifespan. Contrary to expectations for temperate species, growth rates were fairly constant through the year and therefore models including seasonal oscillations were inappropriate. The abundance of this species increased significantly from early spring to early summer, likely due to augmented activity and small‐scale aggregation during the reproductive season that affected our estimates of abundance. No significant recruitment occurred during the 5 years studied. The lack of recruitment during long periods and the slow individual growth rates make A. stellifera particularly vulnerable to local extinction. This study was performed prior to the arrival in the study area of the invasive kelp Undaria pinnatifida and side‐gilled sea slug Pleurobranchaea maculata, species that threaten the community structure where A. stellifera lives. Therefore, the information reported here will be essential to assessing the impacts of these exotic species on this sea star population.  相似文献   
914.
The aim of this study was to investigate the dynamics of abundance, population structure and reproductive variables of the invasive Ponto‐Caspian amphipod Pontogammarus robustoides in its northernmost population, located in the Baltic Sea. Pontogammarus robustoides population variables were studied every month from May to October over 7 years (2002–2008) at two locations in the eastern part of the Gulf of Finland, one site in the north and one in the south. Observations of macrozoobenthos were also conducted once per year in July at 12 sites in this gulf during 2002–2014. This was to monitor the distribution area of P. robustoides and its abundance/biomass in different parts of the Gulf. The results showed that P. robustoides is a widely spread species in the Gulf, preferring to colonize stone‐sandy, vegetated and littoral habitats, from the shore to a depth of 5 m, with water salinity of 0.2–3 ppt. This species co‐exists with other amphipods, such as the Baikalian Gmelinoides fasciatus, the North Atlantic Gammarus tigrinus and the native Gammarus spp. The abundance of P. robustoides varied between the two study sites and among years (2002–2008), reaching a maximum level of 1000 ind.·m?2 for adults and 3000 ind.·m?2 for juveniles. The temperature‐dependent duration of egg development (embryogenesis) in the amphipod and the annual number of generations in P. robustoides populations varied among years. Three generations were recorded in most years and two generations in the coldest years. Clutch size (or fecundity) was dependent on the body length of female and averaged between 33 and 43 eggs per clutch for females ranging in body length from 11.2 to 12.2 mm. A maximum of 75 eggs were observed in a female with a body length of 16 mm. This paper concludes that life‐cycle variables change when P. robustoides spreads from the southern (Ponto‐Caspian region) to northern (Baltic Sea) range areas. In the studied northernmost location, the fecundity and number of generations of this amphipod were 1.5–2‐fold lower compared with the more southern locations. In addition, these variables and P. robustoides abundance were different between the coldest and warmest years at study sites that testify about their distinct dependence on local environmental conditions; further changes in life cycle of this species may be expected together with current climate warming.  相似文献   
915.
我国氨氮海水质量基准的探讨   总被引:2,自引:0,他引:2  
郑磊  张娟  闫振广  刘征涛 《海洋学报》2016,38(4):109-119
我国现行的氨氮海水质量标准参照国外基准与标准制定,未考虑是否能够有效保护中国海洋物种,科学性欠缺。对我国海水氨氮质量基准进行研究,采用美国EPA推荐的物种敏感度排序(SSR)技术,结合美国海水氨氮水质基准数学模型,搜集利用我国15种海水水生生物的非离子氨毒性数据,根据非离子氨氮和总氨氮转换公式,得出水体在不同pH值、温度和盐度条件下的总氨氮水质基准在pH为7.0~9.0、温度为0~30℃的范围内,盐度为10时,基准最大浓度(CMC)和基准连续浓度(CCC)的范围分别为0.089~57.141 mg/L与0.007~4.365 mg/L;盐度为20时,CMC和CCC的范围分别为0.092~61.152 mg/L与0.007~4.671 mg/L;盐度为30时,CMC和CCC的范围分别为0.095~65.446 mg/L与0.007~4.999 mg/L;3个环境因子,对CCC和CMC的影响程度由大到小依次为:pH、温度、盐度。相对于美国,我国急性基准的取值区间收缩了5倍,慢性基准的取值区间收缩了10倍。研究结果认为,现行的非离子氨数值应修正为0.007 mg/L才能有效保护我国海洋生物,同时建议使用总氨氮的基准来管理海水中氨氮变化。为修订我国氨氮海水质量标准提供了科学依据。  相似文献   
916.
互花米草在20世纪70年代后期作为海岸带生态防护工程物种引入我国,由于其超强的繁殖能力,目前已经对我国的滨海湿地生态环境健康与安全造成了严重的威胁,成为生长在中国沿海的一种典型生态入侵植物,引起了相关部门的高度重视。文章选择浙江象山港为重点研究区,通过遥感技术手段,基于2003年,2009年和2014年中分辨率Landsat系列遥感卫星数据,采用空间与光谱特征相结合的综合判读,提出了生境空间环境支持下的植物群落遥感自动识别方法,动态监测了互花米草在象山港的繁衍和入侵过程已经空间格局变化。研究结果表明:过去10年余年,互花米草在象山港呈现指数模型的爆炸性增长。2003年,整个象山港互花米草的分布面积约为590 hm2;2009年其分布面积达到1745 hm2;2014年互花米草在象山港的分布面积超过5715 hm2。2003-1014年10年间互花米草在该区域分布面积翻了近10倍,几乎占据了海岸带所有的泥质海滩,成为象山港滨海湿地区的主导型盐生植被和区域优势种,对附近农田,尤其是淡水水域构成巨大的威胁。而在快速扩张的驱动要素方面,研究认为强劲的自我繁殖性能是互米花草在区域能够快速扩张的主要原因;人类围垦活动促进了这一快速扩张进程。以上研究结论可为区域互花米草的综合治理提供数据支持和遥感监测提供技术参考。  相似文献   
917.
为适应国土资源管理工作新常态的要求,本文在分析增城国土信息化成果的基础上,借助物联网、互联网+、3S等新技术,建立增城国土资源动态监管系统。系统是对增城国土部门信息化建设成果的集成整合和综合应用,本文对系统的总体规划思路、业务架构规划、系统框架设计和主要功能进行介绍。  相似文献   
918.
为探索中国典型城市群新增制造业用地结构与布局状况、发展及功能分工特征,本文基于中国土地市场网2009-2013年制造业用地出让数据,通过区位熵、耦合分析、相关分析等方法,分析了长三角、珠三角、京津冀、长江中游和成渝5个典型城市群新增制造业用地分布特征以及城镇体系耦合特征差异。结果表明:①各城市群新增制造业用地差异显著。长三角、珠三角城市群新增制造业发展较为均衡;京津冀、长江中游和成渝城市群发展协调性仍有待提升。②新增制造业各行业用地在5个城市群中均呈现出一定的集聚特征,其中原材料等传统产业倾向布局在城市群边缘区及城市低等级区;电子信息产业等新兴产业多集中在核心城市及高等级区。③各城市群内部新增制造业用地市场化机制作用较为充分,地价呈现随等级提升而递增的趋势;城市群核心区市场活跃度较低而骨干区较高。相关结论可为城市群产业布局调整、优化以及制定不同等级区域协调发展战略提供参考。  相似文献   
919.
This article is based on my own experiences in the field and the stories of queer Latina immigrant vendors collected from 2004 to 2014. I argue that through an onto-epistemological relational framework, we can further elucidate how entangled social worlds provide new ways of understanding the world we live in. I propose reading the materiality and embodied street vending practices as not separate from, but constitutive with, ideologies about sexuality, gender, and nationality that shape, restrict, and reproduce informal street vending practices in Latino barrios. Particularly, I analyze the embodied entanglements of culturally conservative ideologies about sexuality within immigrant Latino communities across borders, individual experiences with transmigration journeys, and context of reception in Los Angeles.  相似文献   
920.
Resilience is an increasingly important concept within urban studies, economic geography, and evolutionary economics for measuring the capacity of city-regions to respond to economic shocks. In this article, we provide a sympathetic critique of the resilience metaphor in urban studies, which we explicate through an analysis of the recent history of the Vancouver economy. On the surface, Vancouver seemingly showed resilience when it overcame the abrupt decline of its resource-based economy in the 1980s, and established an alternative flourishing “new economy” by the 1990s. But over the last five years, the key local “creative” industries such as video game development and film production have suffered, with a number of large firms leaving Vancouver, and industry employment declining sharply. Drawing on more than 40 interviews conducted over a five-year period with members of the local video game community, our paper documents the rise and more recent decline of Vancouver’s “new economy” sector. Our research raises questions about the value of the resilience metaphor in urban studies and highlights the difficulties facing city-regions reliant on highly mobile “new economy” industries.  相似文献   
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