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101.
2019年春、秋两季,对江西省76个湖泊的底栖动物进行了调查,在分析其群落结构和多样性的基础上,探讨了多样性与环境因子间的关系,旨在确定影响大型底栖无脊椎动物多样性的重要环境因子,以期为江西省湖泊的精准化管理提供科学依据和技术支持。两次调查共检出140个分类单元,以水生昆虫和软体动物为主,摇蚊类物种数占水生昆虫物种数的53.62%。富营养指示种(长足摇蚊属一种和摇蚊属一种)为春、秋两季的优势分类单元,湖沼典型种(长足摇蚊属一种、摇蚊属一种、石田螺属一种、苏氏尾鳃蚓和霍甫水丝蚓)的丰度变化导致了群落结构的季节变化。大型底栖无脊椎动物α多样性水平较低,基于PLSR和PLS-SEM的分析结果表明,影响大型底栖无脊椎动物多样性指标的环境因子既与藻类种群动态密切相关,也与水质状态有关。大型底栖无脊椎动物多样性与藻类种群状态存在稳定的联系,不受季节因素的影响,过高的藻类丰度不利于大型底栖无脊椎动物多样性的提高,而较好的水质状况有利于大型底栖无脊椎动物多样性的提高。为保护江西省湖泊大型底栖无脊椎动物资源,应在具有渔业养殖功能的湖泊和城镇湖泊中进行水生植物的修复工作,使藻型湖泊向草型湖泊方向演化;对一... 相似文献
102.
Recent data from exposures of terrestrial Pleistocene sediments in the Fraser Lowland of southwestern British Columbia reveal at least two ‘Bond cycles’ within Oxygen Isotope Stage 2. The maximum of the Coquitlam Stade coincides with the timing of Heinrich event H2, the Port Moody Interstade with Dansgaard–Oeschger (D–O) interstade 2, the maximum of the Vashon Stade with H1, and the Fort Langley interval with D–O interstade 1. The Sumas Stade apparently preceded H0 (Younger Dryas) but could have been in response to the same climatic signal. The timing of Sumas advances may be explained by a combination of glacio-isostatic rebound, destabilisation of the ice margin, and rapid movement over a short distance on soft muddy beds of a rising sea floor, thereby leading the timing of North Atlantic events by hundreds of years. In contrast, Coquitlam and Vashon advances were mainly over permeable glaciofluvial sediments and because of this their maxima probably did not precede the timing of H2 and H1. The Port Moody Interstade coincided with the global Last Glacial Maximum, due in part to the moderating effect of moist summer storms in a southward-shifted jet stream that influenced the Fraser Lowland at that time. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
103.
地图代数的符号化方法 总被引:2,自引:0,他引:2
根据地学数据库中符号的定位数据和符号码,使用点阵符号库中的符号数据进行符号化,由此得出的图形美观,生动,河流具有粗细变化,该方法简洁通用,具备数据独立性和程序独立性。 相似文献
104.
The karst mountain areas of Southwest China contain barren farmland soils and suffer from nutritional and water deficiencies that affect crop productivity. Hence,it is imperative to apply suitable fertilizers to restore soil fertility and maintain crop yield. The aim of this study is to investigate the effects of mineral-organic fertilizer(MOF)made of potassic rock and organic waste on the growth of crops. For this purpose, green Chinese cabbage grown using three different fertilization methods including MOF,inorganic fertilizer(IF), and a control was evaluated. We determined soil water content, agronomic characteristics,and biomass of green Chinese cabbage in different treatments. Furthermore, surface runoff from the pot experiments and soil leachate from pot experiments were collected to determine water temperature, pH, and cation and anion concentrations. The results demonstrate thatMOF can improve the soil water-holding capacity of soil,and the basic agronomic characteristics of the cabbage treated with MOF were superior to those with IF. Using MOF can promote the increase in cabbage biomass.Additionally, the concentration of inorganic carbon(largely in the form of HCO_3^-) in surface runoff water treated by MOF was higher than the other treatments, establishing carbon sequestration potential. This work provides a novel and environmentally friendly fertilization pattern in karst areas, which will improve crop yield and also increase the carbon sequestration potential of crops. 相似文献
105.
Extreme learning machine for the displacement prediction of landslide under rainfall and reservoir level 总被引:2,自引:1,他引:2
Cheng Lian Zhigang Zeng Wei Yao Huiming Tang 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(8):1957-1972
Landslide prediction is always the emphasis of landslide research. Using global positioning system GPS technologies to monitor the superficial displacements of landslide is a very useful and direct method in landslide evolution analysis. In this paper, an EEMD–ELM model [ensemble empirical mode decomposition (EEMD) based extreme learning machine (ELM) ensemble learning paradigm] is proposed to analysis the monitoring data for landslide displacement prediction. The rainfall data and reservoir level fluctuation data are also integrated into the study. The rainfall series, reservoir level fluctuation series and landslide accumulative displacement series are all decomposed into the residual series and a limited number of intrinsic mode functions with different frequencies from high to low using EEMD technique. A novel neural network technique, ELM, is employed to study the interactions of these sub-series at different frequency affecting landslide occurrence. Each sub-series extracted from accumulative displacement of landslide is forecasted respectively by establishing appropriate ELM model. The final prediction result is obtained by summing up the calculated predictive displacement value of each sub. The EEMD–ELM model shows the best accuracy comparing with basic artificial neural network models through forecasting the displacement of Baishuihe landslide in the Three Gorges reservoir area of China. 相似文献
106.
A strain of thermophilic fungus Aspergillus fumigatus was cultured with K-bearing minerals to determine if microbe-mineral interactions enhance the release of mineralic potassium. Experiments were carried out in two settings, one with the mineral grains and the fungal cells in direct contact, and the other employing a membrane (pore size 0.22 μm) to separate the two. Measurements over a period of 30 days showed that, irrespective of the experimental setup, the concentration of free K in the culture was drastically higher than those in any of the control experiments where no living organism was present. Moreover, the occurrence of mineral-cell physical contact enhanced potassium release by an additional factor of 3 to 4 in comparison to the separation experiments. For contact experiments, Electron Probe Microanalysis revealed the formation of mycelium-mineral aggregates, and Atomic Force Microscopy imaging further indicated the possible ingestion of mineral particles by the fungus cells. Contrasting to what was observed and expected in control experiments, the potassium solubilization rate showed a positive dependence upon pH when fungi and minerals were mixed directly, and exhibited no correlations with solution acidity if cell-rock contact was restrained. These results appear to suggest that A. fumigatus promoted potassium release by means of at least three likely routes, one through the complexation of soluble organic ligands, another appealing to the immobile biopolymers such as the insoluble components of secretion, and the third related to the mechanical forces in association with the direct physical contact between cells and mineral particles. 相似文献
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