Constructed shallow zones along navigation canals: vegetation establishment and change in relation to environmental characteristics     

Ger Boedeltje  Alfons J.P. Smolders  Jan G.M. Roelofs  Jan M. Van Groenendael 《水产资源保护:海洋与淡水生态系统》2001,11(6):453-471

An Erratum has been published for this article in Aquatic Conservation: Marine and Freshwater Ecosystems 12(2), 2002, 251

• 1. In recent decades shallow zones have been constructed along navigation canals in the Netherlands which form a potential new habitat for aquatic macrophytes and helophytes absent from traditional canals.
• 2. The aim of this study was to examine the relationships between the aquatic plant vegetation that becomes established and the physical and chemical characteristics of water and sediment, in order to find the determinants of species composition and the changes therein. Data were collected in 1998 and 1999 from 80 plots in bank zones at varying stages of development since construction along two navigation canals.
• 3. Plots 3–5 years old were partly dominated by rooting submerged macrophytes such as Potamogeton pectinatus, Elodea nuttallii and Potamogeton pusillus; locally non‐rooting species occurred such as Ceratophyllum demersum, Lemna minor and Spirodela polyrhiza. Older plots contained Phragmites australis, locally mixed with free‐floating species. Hydrological isolation from the eutrophic canals was indicated by the presence of Chara vulgaris.
• 4. Characteristics of both water layer and sediment could explain the variation in vegetation composition. Rooting submerged macrophytes predominantly occurred in sites with a thin (<2 cm) layer of sediment with relatively low concentrations of organic matter; moreover, ammonium concentrations in the water layer and sediment pore water were relatively low. Stands of non‐rooting macrophytes and of Phragmites australis were characterized by a relatively thick sediment layer and high ammonium levels in the pore water. Light limitation in turbid water, associated with navigation and eutrophication, may also play a role.
• 5. Although submerged aquatic macrophytes persist for a relatively short time, shallow zones nevertheless function as a habitat for helophyte communities and contribute to a higher aquatic biodiversity than is associated with traditional banks along navigation canals.

Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

微生物菌剂对厨余垃圾堆肥温室气体减排的影响   总被引：2，自引：2，他引：0  

陈文旭  刘逸飞  蒋思楠  武泽月  王骞旗  李国学  李彦明  宫小燕 《农业工程学报》2022,38(23):181-187

为对厨余垃圾堆肥过程中的温室气体进行减排,在60 L强制通风静态堆肥装置中进行为期35 d的厨余垃圾和园林废弃物的联合好氧堆肥试验。在堆肥原料中分别添加复合微生物菌剂VT1000（VT）、枯草芽孢杆菌（BS）和地衣芽孢杆菌（BL）三种菌剂,并以不加菌剂的堆肥处理（CK）作为对照,监测堆肥过程中的CH4和N2O排放,以研究不同微生物菌剂对于厨余垃圾堆肥温室气体排放的影响。结果表明：微生物菌剂的添加会加快堆体升温和促进腐熟,同时能够实现不同程度的温室气体减排。堆肥过程中N2O的排放量在总温室气体二氧化碳排放当量中占比远高于甲烷,达到总排放当量的76.83%～88.57%,排放高峰期分别出现在堆肥初期和腐熟期。甲烷的排放高峰期出现在堆肥降温期,累计排放量达到温室气体总排放当量的1.65%～2.40%。各处理的总温室气体排放当量分别为95.84 kg·t-1（CK）、52.31 kg·t-1（VT）、42.03 kg·t-1（BS）和62.49 kg·t-1（BL）。与CK处理相比,BS处理的总温室气体的减排效果最好,减排率为56.15%,BL处理的减排率最低,为34.80%,VT处理减排率为45.42%。相较于CH4,菌剂对N2O的减排效果更好,可达35.32%～61.86%。结合堆肥过程的温度及各腐熟度指标,该研究选取的微生物菌剂能够在保证堆肥效率和产品质量的前提下有效减少温室气体排放。  相似文献   

Regional Sediment Deficits in the Dutch Lowlands: Implications for Long-Term Land-Use Options (8 pp)     

Michiel J. van der Meulen  Ad J. F. van der Spek  Ger de Lange  Stephan H. L. L. Gruijters  Serge F. van Gessel  Buu-Long Nguyen  Denise Maljers  Jeroen Schokker  Jan P. M. Mulder  Rob A. A. van der Krogt 《Journal of Soils and Sediments》2007,7(1):9-16

Background, Aim and Scope   Coastal and river plains are the surfaces of depositional systems, to which sediment input is a parameter of key-importance. Their habitation and economic development usually requires protection with dikes, quays, etc., which are effective in retaining floods but have the side effect of retarding sedimentation in their hinterlands. The flood-protected Dutch lowlands (so-called dike-ring areas) have been sediment-starved for up to about a millennium. In addition to this, peat decomposition and soil compaction, brought about by land drainage, have caused significant land subsidence. Sediment deficiency, defined as the combined effect of sediment-starvation and drainage-induced volume losses, has already been substantial in this area, and it is expected to become urgent in view of the forecasted effects of climate change (sea-level rise, intensified precipitation and run-off). We therefore explore this deficiency, compare it with natural (Holocene) and current human sediment inputs, and discuss it in terms of long-term land-use options. Materials and Methods: We use available 3D geological models to define natural sediment inputs to our study area. Recent progress in large-scale modelling of peat oxidation and compaction enables us to address volume loss associated with these processes. Human sediment inputs are based on published minerals statistics. All results are given as first-order approximations. Results: The current sediment deficit in the diked lowlands of the Netherlands is estimated at 136 ± 67 million m3/a. About 85% of this volume is the hypothetical amount of sediment required to keep up with sea-level rise, and 15% is the effect of land drainage (peat decomposition and compaction). The average Holocene sediment input to our study area (based on a total of 145 km3) is ~14 million m3/a, and the maximum (millennium-averaged) input ~26 million m3/a. Historical sediment deficiency has resulted in an unused sediment accommodation space of about 13.3 km3. Net human input of sediment material currently amounts to ~23 million m3/a. Discussion: As sedimentary processes in the Dutch lowlands have been retarded, the depositional system's natural resilience to sea-level rise is low, and all that is left to cope is human countermeasure. Preserving some sort of status quo with water management solutions may reach its limits in the foreseeable future. The most viable long-term solutions therefore seem a combination of allowing for more water in open country (anything from flood-buffer zones to open water) and raising lands that are to be built up (enabling their lasting protection). As to the latter, doubling or tripling the use of filling sand in a planned and sustained effort may resolve up to one half of the Dutch sediment deficiency problems in about a century. Conclusions: Conclusions, Recommendations and Perspectives. We conclude that sediment deficiency – past, present and future – challenges the sustainable habitation of the Dutch lowlands. In order to explore possible solutions, we recommend the development of long-term scenarios for the changing lowland physiography, that include the effects of Global Change, compensation measures, costs and benefits, and the implications for long-term land-use options. Recommendations and Perspectives: -  相似文献   

Subtotal ostectomy of dorsal spinous processes performed in nine standing horses     

Perkins JD  Schumacher J  Kelly G  Pollock P  Harty M 《Veterinary surgery : VS》2005,34(6):625-629

OBJECTIVE: To describe and evaluate subtotal ostectomy of dorsal spinous processes (DSP) performed in standing horses. STUDY DESIGN: Retrospective study. SAMPLE POPULATION: Nine adult horses. METHODS: The diseased portions of the DSP were removed with the horses standing and sedated after infiltrating a local anesthetic agent around the affected DSP. Medical records of affected horses were reviewed to determine history, findings of physical and radiographic examination, surgical technique, postoperative complications, and outcome. RESULTS: Five horses had subtotal ostectomy of DSP because of osteomyelitis, and 4 because of impingement and/or fracture of DSP. Affected portions of DSP were removed safely and effectively, with no apparent discomfort to the horses; hemorrhage was minimal. CONCLUSIONS: Subtotal ostectomy of DSP can be performed safely in standing, conscious horses and the risks associated with general anesthesia are eliminated. Hemorrhage is minimal compared to that which occurs when the procedure is performed with horses anesthetized and in lateral recumbency. CLINICAL RELEVANCE: Access and visibility are better when subtotal ostectomy of the DSP is performed with the horse standing rather than anesthetized and in lateral recumbency. Performing subtotal ostectomy of diseased DSP with the horse standing avoids the expense and risks of general anesthesia.  相似文献   

Evaluation of bee venom and hyaluronic acid in the intra-articular treatment of osteoarthritis in an experimental rabbit model     

Ozlem Nisbet H  Ozak A  Yardimci C  Nisbet C  Yarim M  Bayrak IK  Sirin YS 《Research in veterinary science》2012,93(1):488-493

The aim of this study was to investigate bee venom and hyaluronic acid in the intra-articular treatment of osteoarthritis in an experimental rabbit model. Forty-five rabbits were used and they were randomly divided into three groups (BVI, BVII, and HA) and each group was divided to two subgroups to evaluate the radiologic, magnetic resonance imaging, histopathologic, and biochemical evaluation in post treatment second week (a) and twelfth week (b). Radiologically, a significant difference was observed in the HA group (P<0.05). The MRI evaluation of at any time in group BVI(b) was found to be different. No significant differences were seen between the groups, biochemically. Histopathologically, cellularity, and orthochromasia was evident with Safranin-O in the BVI(b) and BVII(a); adhesions were seen in the BVII(a) group and clustering of chondrocyte in the HA(b) group were found to be different. Consequently, intra-articular application of HA and BV for experimental model of osteoarthritis has no significant influence upon recovery after therapy.  相似文献   

基于功能空间分类的抚仙湖流域“3类空间”时空格局变化     

赵筱青  李思楠  谭琨  苗培培  普军伟  卢飞飞  王茜 《水土保持研究》2019,26(4):299-305,313

为了了解高原湖泊流域“3类空间”的布局结构,探析流域在发展过程中“3类空间”的格局变化及其变化趋势,本文以抚仙湖流域为研究对象,从土地功能空间分类的角度研究抚仙湖流域“3类空间”分类体系,并分析了2005—2015年流域“3类空间”时空格局变化特征,为抚仙湖流域生态环境保护决策和国土空间格局优化研究提供理论参考。结果表明:（1）2005—2015年抚仙湖流域城镇空间呈上升趋势,10 a增加了71.37%,农业空间呈下降趋势,10 a减少了6.38%,生态空间先升后降,总体增加了0.48%;（2）2005年、2010年和2015年抚仙湖流域“3类空间”格局基本一致,以生态空间为主,但城镇空间格局、农业空间格局和生态空间格局的分布存在明显差别,城镇空间和农业空间主要分布于抚仙湖流域的北部,而生态空间除抚仙湖湖泊水面外在流域四周均有分布;（3）从变化程度上看,“3类空间”格局变化差异显著,城镇空间和农业空间格局变化主要发生在流域北部,而生态空间则在湖泊中部沿岸地区。  相似文献   

Dietary profile of n‐3 series LC‐PUFAs in rainbow trout under regular stripping condition: Semen production and quality,hepato‐somatic index,haemato‐immunologic values,oxidative stress and fatty acid composition of liver,muscle and semen     

Serpil Mie Yonar  Kenan Kprücü  Sinan zcan 《Aquaculture Research》2020,51(1):370-378

In this study, the semen production and quality, hepato‐somatic index, haemato‐immunologic values, oxidative stress and the fatty acid contents in liver, muscle and semen of rainbow trout fed diets supplemented n‐3 series long‐chain polyunsaturated fatty acids (LC‐PUFAs) under regular stripping condition were investigated. For this aim, three diets (Control, D1 and D2) were prepared. These diets were contained n‐3 LC‐PUFAs (as a percentage of dietary total fatty acid) at 3.14%, 7.84% and 13.63% respectively. Experimental fish were fed with the control and test diets. The highest hepato‐somatic index, spermatologic (semen pH and volume, sperm motility and density), haematologic (haematocrit value, haemoglobin, erythrocyte count, corpuscular volume, haemoglobin and its concentration in corpuscular), immunologic (nitroblue tetrazolium activity, leucocyte count, phagocytic index, protein and immunoglobulin [IgM] in total plasma) and antioxidants (reduced glutathione, catalase, glutathione peroxidase and superoxide dismutase) values were found in fish fed the D2, D1 and control diets respectively (p < 0.01). Increase in the dietary n‐3 LC‐PUFAs was not significantly (p > 0.01) increased the oxidative stress (malondialdehyde) in fish. The results indicated that the n‐3 LC‐PUFAs at 13.63% level of total fatty acid in the diet could increase the semen production and quality, hepato‐somatic index, haematologic and immunologic values, and the n‐3 LC‐PUFA contents in liver, muscle and semen of rainbow trout broodstock under regular stripping condition.  相似文献   

汇水面积阈值对土壤侵蚀定量评价的影响     

丁琳  于现举  符素华  吴思南 《水土保持学报》2018,32(3):61-67,73

土壤侵蚀预报模型是定量评价水土流失和评估水土保持措施效益的重要手段。通用土壤流失方程(Universal Soil Loss Equation,USLE)和中国土壤流失方程(Chinese Soil Loss Equation,CSLE)被广泛应用于土壤侵蚀定量评价。这些模型中坡长的计算受汇水面积阈值的影响较大。为揭示汇水面积阈值对土壤侵蚀定量评价的影响,选取北方土石山区、西北黄土高原区、东北黑土区、南方红壤丘陵区、西南紫色土区、西南山地区和西南岩溶区210个流域面积在0.2~3.0km~2的小流域,以1∶10 000地形图10m分辨率DEM为数据源,分别计算了1 000,1 500,2 000,2 500,3 000,5 000,7 000,9 000,11 000,13 000,15 000m~2共11个汇水面积阈值下各小流域不同坡长、土壤侵蚀强度级别以及土壤侵蚀的面积比例,分析了它们对汇水面积阈值变化的敏感性。结果表明:平均坡长、土壤侵蚀面积和轻度以上各级别的侵蚀强度面积比例都随汇水面积阈值的增加先增加而后趋于稳定。微度侵蚀面积比例随汇水面积阈值的增加逐渐减小并趋于稳定。当汇水面积阈值由1 000m~2增加到15 000m~2时,北方土石山区、西北黄土高原区、东北黑土区、南方红壤丘陵区、西南紫色土区、西南山地区和西南岩溶区的平均坡长分别增至阈值为1 000m~2时的1.53,4.16,1.95,1.90,1.69,1.57,1.47倍;土壤侵蚀面积比例分别增至阈值为1 000m~2时的1.20,1.85,1.43,1.37,1.77,1.44,1.30倍。汇水面积阈值对各分区的影响程度存在差异。从平均坡长和土壤侵蚀面积来看,东北黑土区受汇水面积阈值的影响最大。研究结果不仅为精确评价土壤侵蚀提供了数据支撑,而且对水土保持综合防治措施的评价和优化具有指导意义。  相似文献   

Considering neighborhood effects improves individual dbh growth models for natural mixed-species forests in Mexico     

Gerónimo Quiñonez-Barraza  Dehai Zhao  Héctor M. De Los Santos Posadas  José J. Corral-Rivas 《Annals of Forest Science》2018,75(3):78

  相似文献   

Improved isolation procedure for azaspiracids from shellfish, structural elucidation of azaspiracid-6, and stability studies     

Kilcoyne J  Keogh A  Clancy G  LeBlanc P  Burton I  Quilliam MA  Hess P  Miles CO 《Journal of agricultural and food chemistry》2012,60(10):2447-2455

Azaspiracids are a group of lipophilic polyether toxins produced by the small dinoflagellate Azadinium spinosum. They may accumulate in shellfish and can result in illnesses when consumed by humans. Research into analytical methods, chemistry, metabolism, and toxicology of azaspiracids has been severely constrained by the scarcity of high-purity azaspiracids. Consequently, since their discovery in 1995, considerable efforts have been made to develop methods for the isolation of azaspiracids in sufficient amounts and purities for toxicological studies, in addition to the preparation of standard reference materials. A seven-step procedure was improved for the isolation of azaspiracids-1-3 (1, 2, and 3) increasing recoveries 2-fold as compared to previous methods and leading to isolation of sufficiently purified azaspiracid-6 (6) for structural determination by NMR spectroscopy. The procedure, which involved a series of partitioning and column chromatography steps, was performed on 500 g of Mytilus edulis hepatopancreas tissue containing ~14 mg of 1. Overall yields of 1 (52%), 2 (43%), 3 (43%), and 6 (38%) were good, and purities were confirmed by NMR spectroscopy. The structure of 6 was determined by one- and two-dimensional NMR spectroscopy and mass spectrometry. The stability of 6 relative to 1 was also assessed in three solvents in a short-term study that demonstrated the greatest stability in aqueous acetonitrile.  相似文献