P507萃淋树脂吸附稀土的性能研究和应用   总被引：5，自引：0，他引：5  

宋金如  龚治湘  余锴纯 《华东地质学院学报》2000,23(4):351-355

采用静动态两种方法较系统地研究了Ｐ５０７萃淋权脂吸附稀土的性能,并选择了分离稀土总量的最佳条件。用于标准矿样中稀土总量的测定,分析结果与标准值相近。  相似文献   

Detecting nutrient deficiency in spruce forests using multispectral satellite imagery     

《International Journal of Applied Earth Observation and Geoinformation》2020

Nutrient deficiency in forest stands has a negative impact on timber production. Although there are numerous studies investigating nutrient deficiency in forests using remote sensing, research has usually focused on extracting nutrient/pigment concentrations using hyperspectral imagery. Results of studies using this method of assessment are uncertain at the canopy level. This study proposes using freely available multispectral imagery to identify nutrient deficiency in commercially managed forest plantations. A classification map of nutrient deficient, healthy, and a third class, other, for State spruce forests in the Republic of Ireland was constructed using multispectral Sentinel 2 images from Spring and a Random Forest model. The forest area of interest (AOI) was Sitka spruce or Norway spruce plantations greater than 12 years old. Results showed that the overall accuracy was 89% and the associated Kappa Index of agreement was 79%. An unbiased area estimator was vital for an accurate estimate of the scale of nutrient deficiency, which concluded that 23% of the AOI was nutrient deficient. Early detection of nutrient deficiency is crucial to mitigate negative impacts on productivity so a time series analysis of the spectral response of healthy and nutrient deficient classes using Google Earth Engine's Landsat 5, 7, and 8 archive was carried out. A control of known nutrient deficient sites, as identified through foliar analysis, was used for comparison with the nutrient deficient and healthy training data. The spectral response showed a decrease through time for all of the foliar analysis and training data using the green (520–600 nm), red (630–690 nm), and SWIR spectra (1550–1700 nm) during Spring. This decreasing trend is due to the growth of foliage, with the difference in spectral response between nutrient deficient and healthy stands being attributed to the presence of chlorosis in stands suffering from nutrient deficiency. Spectral thresholds using digital numbers for nutrient deficient stands were identified for an operational optimum age cohort of between 10–12 years old which will be used for early detection.  相似文献   

Diapycnal nutrient fluxes on the northern boundary of Cape Ghir upwelling region     

《Deep Sea Research Part I: Oceanographic Research Papers》2014

In this study we estimate diffusive nutrient fluxes in the northern region of Cape Ghir upwelling system (Northwest Africa) during autumn 2010. The contribution of two co-existing vertical mixing processes (turbulence and salt fingers) is estimated through micro- and fine-structure scale observations. The boundary between coastal upwelling and open ocean waters becomes apparent when nitrate is used as a tracer. Below the mixed layer (56.15±15.56 m), the water column is favorable to the occurrence of a salt finger regime. Vertical eddy diffusivity for salt (K_s) at the reference layer (57.86±8.51 m, CI 95%) was 3×10⁻⁵ (±1.89×10⁻⁹, CI 95%) m² s⁻¹. Average diapycnal fluxes indicate that there was a deficit in phosphate supply to the surface layer (6.61×10⁻⁴ mmol m⁻² d⁻¹), while these fluxes were 0.09 and 0.03 mmol m⁻² d⁻¹ for nitrate and silicate, respectively. There is a need to conduct more studies to obtain accurate estimations of vertical eddy diffusivity and nutrient supply in complex transitional zones, like Cape Ghir. This will provide us with information about salt and nutrients exchange in onshore–offshore zones.  相似文献   

随枣北部地区燕山期花岗岩体构造环境探讨     

王春梅  李丰硕  周永涛  蔡丽娟 《国土资源情报》2014,(4):51-55

随枣北部地区发育大量燕山期花岗岩体,以新黄断裂为界,南西侧主要为二长花岗岩,北东侧为钾长花岗岩。主要造岩矿物为钾长石、斜长石、黑云母和石英。岩浆岩总体酸度较高,高铝、相对富钾,以准铝质到过铝质钙碱性岩为主,属高钾一钾玄质系列。根据岩石化学参数判别为造山晚期花岗岩,属构造转折时期的岩石组合;微量元素蛛网图识别为同碰撞花岗岩和碰撞后花岗岩;微量元素对判别为同碰撞花岗岩（syn-COLG）和火山弧花岗岩（VAG）;采用巴尔巴林构造环境识别为富钾钙碱性花岗岩类（KCG）;Maniar和Piccoli构造环境判别属造山环境下的花岗岩。通过综合评判,结合区域大地构造演化规律,其构造环境应属于后碰撞阶段,地球动力学环境应为构造体制转换期。  相似文献   

Effects of anthropogenic disturbance on the abundance and size of epibenthic jellyfish Cassiopea spp     

Stoner EW  Layman CA  Yeager LA  Hassett HM 《Marine pollution bulletin》2011,62(5):1109-1114

Jellyfish blooms in pelagic systems appear to be increasing on a global scale because of anthropogenic impacts, but much less is known about the link between human activities and epibenthic jellyfish abundance. The aim of this study was to investigate whether the epibenthic jellyfish, Cassiopea spp., were found in greater abundance, and attained larger sizes, in coastal habitats adjacent to high human population densities compared to sites adjacent to uninhabited areas on Abaco Island, Bahamas. Cassiopea spp. were found to be significantly more dense and larger in areas with high human population densities. Ambient nutrient levels and nutrient content of seagrass were elevated in high human population density sites, and may be one mechanism driving higher abundance and size of Cassiopea spp. Cassiopea spp. may have important effects on community structure and ecosystem function in critical coastal ecosystems (e.g., seagrass beds), and their impacts warrant further study.  相似文献   

云南省中西部红色风化壳中铂族元素分布特征   总被引：1，自引：0，他引：1  

刘英超  杨竹森  田世洪  于玉帅 《地质学报》2011,85(2):272-281

近年来,铂族元素以其广泛的地质活动环境受到越来越多的关注,人们对铂族元素的研究也从其在硫化物熔体、硅酸盐熔体和热液流体中的富集成矿行为逐渐延展到其在表生风化过程中的地球化学迁移行为.本文通过对我国云南省中西部潞西菲红、元谋朱布和弥渡金宝山3个具有铂族元素矿化的超基性岩体形成的红色风化壳研究发现,三地风化壳化学风化程度远...  相似文献   

Mussel farming as a nutrient reduction measure in the Baltic Sea: consideration of nutrient biogeochemical cycles   总被引：1，自引：0，他引：1  

Stadmark J  Conley DJ 《Marine pollution bulletin》2011,62(7):1385-1388

Nutrient loads from the land to the sea must be reduced to combat coastal eutrophication. It has been suggested that further mitigation efforts are needed in the brackish Baltic Sea to decrease nutrients, especially in eutrophic coastal areas. Mussel farming is a potential measure to remove nutrients directly from the sea. Mussels consume phytoplankton containing nitrogen (N) and phosphorus (P); when the mussels are harvested these nutrients are removed from the aquatic system. However, sedimentation of organic material in faeces and pseudo-faeces below a mussel farm consumes oxygen and can lead to hypoxic or even anoxic sediments causing an increased sediment release of ammonium and phosphate. Moreover, N losses from denitrification can be reduced due to low oxygen and reduced numbers of bioturbating organisms. To reveal if mussel farming is a cost-effective mitigation measure in the Baltic Sea the potential for enhanced sediment nutrient release must be assessed.  相似文献   

Ecology and functional roles of biological soil crusts in semi-arid ecosystems of Spain   总被引：1，自引：0，他引：1  

F.T. Maestre  M.A. Bowker  Y. Cantón  A.P. Castillo-Monroy  J. Cortina  C. Escolar  A. Escudero  R. Lázaro  I. Martínez 《Journal of Arid Environments》2011,75(12):1282-1291

Biological soil crusts (BSCs), composed of lichens, cyanobacteria, mosses, liverworts and microorganisms, are key biotic components of arid and semi-arid ecosystems worldwide. Despite they are widespread in Spain, these organisms have been historically understudied in this country. This trend is beginning to change as a recent wave of research has been identifying BSCs as a model ecological system. Many studies and research projects carried out in Spain have explored the role of BSCs on water, carbon and nitrogen fluxes, the interactions between BSCs and vascular plants, their dynamics after disturbances, and their response to global change, among other topics. In this article we review the growing body of research on BSCs available from semi-arid areas of Spain, highlighting its importance for increasing our knowledge on this group of organisms. We also discuss how it is breaking new ground in emerging research areas on the ecology of BSCs, and how it can be use to guide management and restoration efforts. Finally, we provide directions for future research on the ecology of BSCs in Spain and abroad.  相似文献   

黄海大海洋生态系区域监测体系建设的对策建议          下载免费PDF全文

王孝程  贾川  张怡  靳青青  王紫竹  刘永健  王燕  邵魁双  王守强  关春江  郭皓 《海洋开发与管理》2022,39(2):88-94

为促进黄海生态环境保护和生态灾害治理工作,文章基于历史资料的收集和整理,分析黄海大海洋生态系的生态环境背景及其存在的问题,并提出区域监测体系建设的对策建议。研究结果表明:黄海大海洋生态系的气候变化和营养盐变化是浮游生物群落的重要影响因素,赤潮、绿潮和水母暴发是黄海大海洋生态系的主要生态灾害;应通过加强各种形式的监测和合作,不断构建黄海大海洋生态系区域监测体系。  相似文献   

How EU policies could reduce nutrient pollution in European inland and coastal waters     

《Global Environmental Change》2021

Intensive agriculture and densely populated areas represent major sources of nutrient pollution for European inland and coastal waters, altering the aquatic ecosystems and affecting their capacity to provide ecosystem services and support economic activities. Ambitious water policies are in place in the European Union (EU) for protecting and restoring aquatic ecosystems under the Water Framework Directive and the Marine Strategy Framework Directive. This research quantified the current pressures of point and diffuse nitrogen and phosphorus emissions to European fresh and coastal waters (2005–2012), and analysed the effects of three policy scenarios of nutrient reduction: 1) the application of measures currently planned in the Rural Development Programmes and under the Urban Waste Water Treatment Directive (UWWTD); 2) the full implementation of the UWWTD and the absence of derogations in the Nitrates Directive; 3) high reduction of nutrient, using best technologies in wastewaters treatment and optimal fertilisation in agriculture. The results of the study show that for the period 2005–2012, the nitrogen load to European seas was 3.3–4.1 TgN/y and the phosphorus load was 0.26–0.30 TgP/y. Policy measures supporting technological improvements (third scenario) could decrease the nutrient export to the seas up to 14% for nitrogen and 20% for phosphorus, improving the ecological status of rivers and lakes, but widening the nutrient imbalance in coastal ecosystems (i.e. increasing nitrogen availability with respect to phosphorus), affecting eutrophication. Further nutrient reductions could be possible by a combination of measures especially in the agricultural sector. However, without tackling current agricultural production and consumption system, the reduction might not be sufficient for achieving the goals of EU water policy in some regions. The study analysed the expected changes and the source contribution in different European regional seas, and highlights the advantages of addressing the land-sea dynamics, checking the coherence of measures taken under different policies.  相似文献