Study on the Soil Carbon Pool and Potential Capacity of Carbon Sequestration in the Northern Tibetan Plateau     

Yafeng Zhang  Zhen Yao  Qiang Ma  Bingyan Ji  Guowen Miao  Guang Xu  Fengjuan Ma 《地球科学进展》2018,33(2):206-212

It is important to investigate the soil organic carbon reserves of the northern Tibetan Plateau for understanding the global carbon cycle. The surface soil carbon storage is 1.27×10⁸ t, and the surface topsoil organic carbon density is 4.96×10³ t/km² in the study area. Compared with the results of the second National Soil Census, the distribution of organic carbon reserves of chestnut soil, sierozem, alpine steppe soil, swamp soil, sandy soil and ustic cambisols increased gradually, which are mainly distributed in savanes of the northern Qinghai Lake and woodland in middle-high mountain areas of the eastern Qinghai Lake; savanes and woodland are classified as the carbon sink area because this area’s carbon sequestration is greater than the release quantity. By contrast, the distribution of organic carbon reserves of mountain meadow soil, alpine meadow soil, grey cinnamon soil, chernozem and anthropogenic-alluvial soil decreased gradually, which are mainly distributed in the farming areas of eastern Qinghai Province. This area’s carbon sequestration is less than the release quantity because of cultivation effect, and is classified as the carbon source area. The 97.5% of organic carbon storage cumulative frequency is closed to the threshold value of the organic carbon saturation. The carbon sequestration potential of the study area is 241.57×10⁶ t. Take the widely distributed chestnut soil as a case, it will take 18.66 years to reach saturation for the soil organic carbon reserves of chestnut soil.  相似文献   

老挝万象钾盐矿床盐背斜成因与判别标识初步研究          下载免费PDF全文

石国成  朱登贤  张西营  李彦强 《盐湖研究》2022,30(2):128-138

识别盐构造对于研究盐体改造作用、钾盐成矿预测以及钾盐矿山的安全开采利用等方面具有重要作用。本文以老挝万象钾盐矿区为主要研究对象,分析了区域盐背斜成因并尝试构建识别标志。研究表明,重力异常分布可以指示和圈定盐背斜构造位置和分布特征,研究区盐背斜的形成与古河道切割具有密切的成因联系,盐背斜构造在地形地貌上具有明显的响应特征。上述研究结果对于深入认识该区域钾盐矿床的成因与后期改造作用过程具有重要意义。  相似文献   

上海市工业园区土地二次开发的困境与对策     

陈基伟 《上海国土资源》2012,33(1):46-50

上海工业园区土地面临可供增长空间有限的瓶颈制约,必须盘活存量进行二次开发才能实现集约增长。从拓展发展空间与提升产业结构两方面对二次开发进行重新认识。在全面总结全市工业园区以往土地二次开发成效基础上,对所面临困境进行了剖析：创新与成熟模式尚未完全建立;缺乏有效地市场化运作机制;尚未形成整体性政策安排与产业战略层面顶层设计。从规划统筹、土地储备、供地方式以及产业分类等方面对有关困境进行了分析,并提出制定二次开发规划、加强工业园区联动、完善储备与供地机制、积极制订配套政策等相关对策建议。  相似文献   

Setting quotas using provisional data: a case study from the South Australian abalone fisheries     

J Dent  S Mayfield  B Stobart  J Carroll 《新西兰海洋与淡水研究杂志》2016,50(3):371-388

Stock assessments of quota or effort managed fisheries in which the duration of the fishing season is 12 months are invariably delivered well into the subsequent fishing season. As a result, quotas are frequently based on year-old data. This delay is often unavoidable because it may take months to collect, collate and analyse data necessary to assess fishery performance. The South Australian fisheries for blacklip (Haliotis rubra Leach, 1814) and greenlip abalone (H. laevigata Donovan, 1808) have addressed this issue by using provisional data on current stock status to inform application of the harvest strategy decision rules that set the quota for the next year. The primary index of relative abundance for these fisheries is catch per unit effort (CPUE). Our study uses 25 years (1988–2012) of CPUE data to quantify the differences between the provisional and complete-season CPUE estimates at the spatial scales used to assess the fisheries. We demonstrate that, in most cases, there was a strong relationship between the provisional and complete-season CPUE estimates for both species, with little evidence of bias. As the provisional CPUE estimates were a reliable and accurate predictor of the complete-season CPUE estimates, this provides a high degree of confidence in using provisional CPUE estimates to set quotas, thereby overcoming the difficulty of basing decisions on aged data. These findings are likely to be applicable to other fisheries, particularly those where much of the annual catch is obtained (or effort expended) in a short time period at the commencement of the fishing season.  相似文献   

Spawning hoki (Macruronus novaezelandiae Hector) concentrations in Cook Strait and off the east coast of the South Island,New Zealand,August‐September 1987     

Mary E. Livingston 《新西兰海洋与淡水研究杂志》2013,47(4):503-517

Abstract

In September 1986, dense concentrations of freshly spawned hoki (Macruronus novaezelandiae) eggs were located in eastern Cook Strait. A follow‐up exploratory trawl survey of Cook Strait and the east coast of the South Island, in August and September 1987, located concentrations of spawning hoki in canyon features in Cook Strait, off the Kaikoura coast, and off Banks Peninsula. The largest concentration, 14 km long, 4 km wide, and up to 150 m thick occurred in Cook Strait Canyon, with catch rates of hoki up to 48 t h^?1. Gonad conditions of male and female hoki showed they were actively spawning. Catch rates in Cook Strait Canyon were comparable to the main fishery on the west coast of the South Island but were much lower off Kaikoura and Banks Peninsula. Hoki associated with spawning concentrations were not feeding. Bycatch species were mostly ling (Genypterus blacodes) and spiny dogfish (Squalus acanthias), and both were preying on hoki. Spiny dogfish were also feeding on spawned fish eggs. The possible stock structure of hoki is discussed.  相似文献   

Status of the major lobster fisheries in India     

E.V. Radhakrishnan  V.D. Deshmukh  Mary K. Manisseri  M. Rajamani  Joe K. Kizhakudan  R. Thangaraja 《新西兰海洋与淡水研究杂志》2013,47(3):723-732

Commercial exploitation of lobsters from the Indian seas began in the 1950s. Annual landings have been declining from a peak of 4075 t in 1985 to 1364 t in 2002. Major fisheries were located on the north‐west, south‐west, and south‐east coasts. Among the 12 species recorded, only four species of spiny lobsters (three littoral and one deep sea) and one species of slipper lobster are commercially important. At Kayalpattinam and Tharuvaikulam, on the south‐east coast, lobster landings sharply declined for the gill‐net fishery. Of the two species that contributed to the fishery, Panulirus ornatus and Panulirus homarus, the latter has been more affected owing to high vulnerability to fishing activities. Catch composition analysis of the trammel‐net fishery showed that 35% of the landings consisted of P. homarus in the size range of 23–50 mm carapace length. On the north‐west coast, the spiny lobster Panulirus polyphagus and the slipper lobster Thenus orientalis are incidentally caught in trawl nets. However, the fishery for T. orientalis in the waters off Mumbai lasted only up to 1994. Large‐scale exploitation of spawning females, which formed 60% of the total catch, might have been detrimental to the recruitment process resulting in rapid decline and total collapse of the fishery. Abundance of P. polyphagus reached its maximum during September, constituting 23% of the average annual landing during 1988–2002. A high exploitation ratio (>0.7) indicated over‐fishing of the stock. Repeated spawning and high annual egg production are probably responsible for sustaining the stock, despite over‐exploitation. Major problems confronting the resource management of the multi‐gear and multi‐species lobster fisheries in India are discussed. An operational project, involving fisher community, has been taken up for creating awareness of the need for sustainable exploitation of the resource. Regulatory measures, such as closure of the fishery during the peak of the breeding season, ban on trammel‐net, mandatory release of egg‐bearing lobsters, and establishment of lobster sanctuaries are suggested to the State Governments for implementation.  相似文献   

Population dynamics and fishery management of the paua,Haliotis iris     

K. J. Sainsbury 《新西兰海洋与淡水研究杂志》2013,47(2):163-173

A population model is developed and used in conjunction with the results of a study of an unexploited population of paua (Haliotis iris Martyn) to examine the historical pattern of recruitment and yield per recruit. As H. iris cannot yet be aged, the population model uses size rather than age classes, but is structurally similar to the Leslie matrix model. Simulations suggest that the observed population size structure resulted from a short (about 5 year) period of high recruitment, preceded and followed by longer periods of low recruitment. Yield per recruit analysis shows that the present minimum legal size for the fishery (127 mm) provides close to the maximum yield per recruit for most stocks, although yield per recruit could be increased in some areas by a reduction in minimum legal size.  相似文献   

A spatial- and age-structured assessment model to estimate the impact of illegal fishing and ecosystem change on the South African abalone Haliotis midae resource     

《African Journal of Marine Science》2013,35(2):207-236

The management of abalone stocks worldwide is complicated by factors such as illegal fishing combined with the difficulties of assessing a sedentary (but not immobile) resource that is often patchily distributed. The South African abalone Haliotis midae fishery is faced with an additional problem in the form of a relatively recent movement of rock lobsters Jasus lalandii into much of the range of the abalone. The lobsters have heavily reduced sea urchin Parechinus angulosus populations, thereby indirectly negatively impacting juvenile abalone which rely on the urchins for shelter. A model is developed for abalone that is an extension of more standard age-structured assessment models because it explicitly takes spatial effects into account, incorporates the ecosystem change effect described above and estimates the magnitude of substantial illegal (‘poached’) catches. The model is simultaneously fitted to catch per unit effort and Fishery-Independent Abalone Survey abundance data, as well as to several years of catch-at-age (cohort-sliced from catch-at-size) data for the various components of the fishery and different spatial strata. It constitutes the first quantitative approach applied to the management of this commercially valuable resource in South Africa and has provided a basis for management advice over recent years by projecting abundance trends under alternative future catch levels.  相似文献   

The 2004 re-assessment of the South African sardine and anchovy populations to take account of revisions to earlier data and recent record abundances     

《African Journal of Marine Science》2013,35(3):333-348

Hydroacoustic surveys off the coast of South Africa over the early years of the 21st century indicated that both the sardine Sardinops sagax and anchovy Engraulis encrasicolus populations had simultaneously reached record abundances. The South African pelagic fishery is regulated using an Operational Management Procedure (OMP). The OMP in use at that time had been developed using data from the two populations prior to this rapid and substantial increase in abundances. This paper documents the revised assessments that were urgently required to provide a basis to update the OMP. These assessments resulted in a changed perception of the status and productivity of these populations. In particular, estimates of the stock-recruitment relationships and the extent of variation about them, which play a key role in evaluating risk when developing OMPs, altered substantially from estimates derived from earlier assessments.  相似文献   

丹凤地区光石沟铀矿床大毛沟岩株锆石U-Pb同位素定年及其地质意义   总被引：3，自引：0，他引：3  

左文乾  沙亚洲  陈冰  罗忠戍  张展适 《铀矿地质》2010,26(4):222-227

丹凤地区是我国伟晶岩型铀矿床的重要产区,光石沟铀矿床是该区最大的铀矿床之一,大毛沟岩株与光石沟铀矿床有密切的空间关系与成因联系。本文采用锆石LA-ICP-MS定年方法测定了大毛沟岩株的U-Pb同位素年龄,获得了代表大毛沟岩株形成年龄的锆石谐和曲线加权平均值年龄为418.3±8.8 Ma,与光石沟铀矿床的成矿年龄相当,说明光石沟铀矿床的成矿作用在时间上与该岩株的形成时间相当。同时,残留锆石中1980.5±19.47 Ma年龄的发现,说明大毛沟岩株白岗质花岗岩的物源可能与中下地壳秦岭群有关;E颗粒内核465Ma的年龄则可能代表灰池子岩体片麻状二长花岗岩的形成年龄,表明大毛沟岩株与灰池子岩体的形成年龄之间存在约30 Ma的时差。  相似文献