Phytoplankton life cycle transformations lead to species-specific effects on sediment processes in the Baltic Sea     

Kristian Spilling  Magnus Lindstrm 《Continental Shelf Research》2008,28(17):2488-2495

In order to study the sediment response to different addition of organic matter, we added cultures of the dinoflagellates Scrippsiella hangoei and Woloszynskia halophila and the diatom Pauliella taeniata to aquaria containing natural sediment. The biomass added was 1550–3260 mg C m⁻², and in the control, no biomass was added (n=3). Oxygen profiles at the sediment–water interface and inorganic nutrients in the near bottom water were determined once a week. In the additions of P. taeniata and W. halophila the sediment quickly became anoxic, and subsequently there was a flux of >1 mmol PO₄³⁻ m⁻² d⁻¹ out of the sediment in these treatments. The majority of the released P came from P stored in the sediment and not from the organic phosphorus added. The result was very different for the S. hangoei addition. This species underwent a life cycle change to form temporary cysts. During this process there was a net uptake of nutrients. After the formation of cysts the concentration of inorganic nutrient was similar to that of the control. Cysts generally survive for long periods in the sediment (months to years) before germinating, but can also be permanently buried in the sediment. The novel idea presented here is that the phytoplankton composition may directly affect sediment processes such as oxygen consumption and phosphorus release, through species-specific life cycle changes and yields of resting stages produced prior to sedimentation. This can be an important aspect of nutrient cycling in eutrophic waters, like the Baltic Sea, where there is large year-to-year difference in the amount of resting stages settling at the sea floor, mainly due to differences in abundance of diatoms and dinoflagellates during the spring bloom. If yields of resting stages change, e.g. due to changes in the phytoplankton community, it may lead to alterations in the biogeochemical cycling of nutrients.  相似文献   

Alteration of bottom roughness by benthic organisms in a sandy coastal environment     

J. Guilln  S. Soriano  M. Demestre  A. Falqus  A. Palanques  P. Puig 《Continental Shelf Research》2008,28(17):41

This work deals with the potential influence of benthic communities on the sediment dynamics of the coastal zone, and specifically with the modifications to bottom roughness caused by communities and their effects on wave propagation across the coastal profile. Time-series of video observations of the sea bottom on the Ebro delta coast were analysed in order to estimate the bottom roughness associated with physical and biological morphological components and the sediment reworking rates caused by epifaunal organisms. Biological roughness was mainly caused by ophiuroids and tanatocenosis of bivalve and gastropod shells, which changed their abundance during the study period. The total biological roughness (K_bio) ranged between 0.27 and 0.81 cm and represented a significant part (<20%) of the total form drag roughness. Flattening of ripples caused by bioturbation was observed under low-energy conditions. Surface sediment perturbation and bioturbation rates were also estimated. Based on these observations a wave propagation model was applied in order to carry out a sensitivity analysis of the significance of biological roughness on wave dissipation in the study area under different wave conditions.  相似文献   

典型喀斯特地区马尾松纯林及马尾松-阔叶树混交林营养元素生物循环研究——以贵州龙里为例   总被引：3，自引：0，他引：3  

李茜  杨胜天  盛浩然  盛岩  李巍  李顺江 《中国岩溶》2008,27(4):321-328

以龙里典型喀斯特地区马尾松纯林及马尾松- 阔叶树混交林为研究对象,研究了两个群落的生物量、营养元素贮量、分布及循环特征。结果表明: 马尾松纯林、马尾松- 阔叶树混交林的生物量分别为40. 62t /hm2、48. 32t /hm2 ,混交林的乔木层总生物量比马尾松纯林高18. 97% ,根系生物量较纯林高65. 12%。混交林乔木层各器官营养元素的含量整体大于马尾松纯林,两群落乔木层N、P、K、S的含量表现出一致的趋势,叶> 根> 枝> 干。混交林乔木层各元素的积累量分别比纯林高47. 97%～ 197. 67% ,凋落物层各元素贮量比纯林高85. 40%～ 318. 301%。混交林的年归还量、年存留量和年吸收量均大于马尾松纯林,且各元素循环系数大于马尾松纯林。马尾松林与阔叶树混交可以有效地提高群落生物量和营养元素循环的能力。   相似文献   

The role of iron and sulfur in the visual appearance of lake sediment varves     

Veronika Gälman  Johan Rydberg  Andrei Shchukarev  Staffan Sjöberg  Antonio Martínez-Cortizas  Richard Bindler  Ingemar Renberg 《Journal of Paleolimnology》2009,42(1):141-153

Easily discernible sediment varves (annual laminations) may be formed in temperate zone lakes, and reflect seasonal changes in the composition of the accumulating material derived from the lake and its catchment (minerogenic and organic material). The appearance of varves may also be influenced by chemical processes. We assessed the role of iron (Fe) and sulfur (S) in the appearance of varves in sediments from Lake Nylandssjön in northern Sweden. We surveyed Fe in the lake water and established whether there is internal transport of Fe within the sediment. We used a unique collection of seven stored freeze cores of varved sediment from the lake, collected from 1979 to 2004. This suite of cores made it possible to follow long-term changes in Fe and S in the sediment caused by processes that occur in the lake bottom when the sediment is ageing. We compared Fe and S concentrations using X-ray fluorescence spectroscopy (XRF) in specific years in the different cores. No diagenetic front was found in the sediment and the data do not suggest that there is substantial vertical transport of Fe and S in the sediment. We also modeled Fe and S based on thermodynamic, limnological, and sediment data from the lake. The model was limited to the five components H⁺, e^?, Fe³⁺, SO₄ ^2?, H₂CO₃ and included the formation of solid phases such as Fe(OH)₃ (amorphous), FeOOH (aged, microcrystalline), FeS and FeCO₃. Modeling showed that there are pe (redox) ranges within which either FeS or Fe(OH)₃/FeOOH is the only solid phase present and there are pe ranges within which the two solid phases co-exist, which supports the hypothesis that blackish and grey-brownish layers that occur in the varves were formed at the time of deposition. This creates new possibilities for deciphering high-temporal-resolution environmental information from varves.  相似文献   

Effects of Salt on Microbial Populations and Treatment Performance in Purifying Saline Sewage Using the MUCT Process     

《洁净——土壤、空气、水》2009,37(8):649-656

  相似文献   

中国南方表层岩溶系统的碳循环及其生态效应   总被引：65，自引：8，他引：57       下载免费PDF全文

蒋忠诚 《第四纪研究》2000,20(4):325-334

表层岩溶系统因碳酸盐岩－水－CO²(气)三相的化学动态不平衡过程而产生特殊的碳循环环节,参加循环的碳包括碳酸盐岩中的碳、大气和土壤空气CO²部分。中国南方表层岩溶系统的碳循环非常活跃,并敏感地响应岩溶动力因素的变化,从而促进了地球化学过程和生物化学过程的结合,成为大气CO²汇的重要项。中国南方表层岩溶系统的碳循环通过驱动环境的元素迁移,促进土壤有机质的积累,并影响植物所需要的矿物质营养元素的全量和有效态,进而影响岩溶区的植物物种、特有性和作物的发育。  相似文献   

洞庭湖区湿地生物资源特征及生态系统评价   总被引：10，自引：0，他引：10  

庄大昌 《热带地理》2000,20(4):261-264

洞庭湖湿地是我国最大的淡水湖泊湿地生态景观系统,生态资源十分丰富,其中植物资源1428种,鸟类资源216种,鱼类资源119种,哺乳类22种,两栖爬行类27种及其它大量的野生生物资源。根据生物资源的分布状对湖区湿地生态系统进行了分类,即环湖丘岗生态系统,湖州草滩生态系统,湖岸带生态系统,浅水层生态系统、深水层生态系统。在此基础上,对湖区湿地生态系统的功能效益进行了综合评价。按直接利用价值和间接利用价值进行了分类,最后对湿地生物资源保护和开发中存在的问题,并就今后本区湿地生物资源的保护和利用提出了一些设想和建议。  相似文献   

地幔不均一性与地幔循环的多维表征和原因思考     

郑建平  刘为先  王伟  马强  吴树成  戴宏坤 《地质学报》2024,98(3):662-679

地幔早先经核- 幔- 壳分异形成,后受不同尺度对流和循环的影响,因而具有不均一性特征。近三十年来,地幔化学通过研究大洋玄武岩发现了多样地幔端元和非放射性同位素证据并证明了地幔不均一性,逐渐建全了地幔地球化学体系。然而,地幔不均一性如何对应于时空尺度的地幔循环,以及地球演化如何影响地幔不均一性等,仍不清楚。此外,地球物理研究显示,岩石圈厚度差异、中下地幔的波速异常体以及俯冲板片形态的观测为纵横向对流系统提供了空间不均一性证据支持。联合地球化学和地球物理手段对研究地幔不均一性至关重要,用好透视地幔成分与结构的“双目镜”已成为共识。本文从地幔不均一性结合地球化学场、地球物理的不同表现形式,以及现今及历史时期的洋陆格局的对比,多维度联系地幔循环和演化,思考了超大陆旋回与地幔不均一化的内在逻辑。强调了从全球演化角度看地幔不均一性的重要性和提出多手段联合建立地幔循环驱动模型的展望。  相似文献   

Getting by: The ethnomethods of everyday cycling navigation     

Michael Lloyd 《New Zealand geographer》2020,76(3):207-220

Cycling is often carried out in public places, meaning that it is easy to both observe and video-record cycling in action. Within sociology, ethnomethodology focuses on practical activities, often by collecting and analysing video data. Geographers have also used video data in researching cycling, but the two perspectives have little crossover. This article showcases an ethnomethodological analysis of video data on everyday cycling navigation, presenting three empirical examples. We see that cycling, accomplished by real interacting people, needs analysing in fine detail. Further knowledge of the mundane aspects of cycling mobility can usefully build upon such a videographic approach.  相似文献   

生物传感器综述     

崔桂媛 《成都信息工程学院学报》1993,(3)

本文介绍当前国际、国内生物传感器的发展及应用概况,并对生物传感器的市场前景和生物传感器技术的未来发展作了简单地论述。  相似文献