基于次溴酸钠氧化-氨基磺酸还原测定沉积物15N加富培养样品中的15NH+4的方法探索     

徐颢铭  宋国栋  刘素美  梁生康  张桂玲 《海洋学报》2022,44(1):147-154

沉积物中的异化硝酸盐还原过程是海洋中活性氮转化的关键过程之一.不同于反硝化和厌氧铵氧化,异化硝酸盐还原为铵(DNRA)是将硝酸盐直接还原为铵,而不是以氮气的形态移除,这有可能会加重水体富营养化和缺氧.目前测定沉积物中异化硝酸盐还原过程的主要手段是15N标记培养技术.为了准确评估DNRA的潜在速率,首先要准确测定加富样品...  相似文献   

Tidal exchange of nitrogen and phosphorus between a mesohaline vegetated marsh and the surrounding estuary in the lower Chesapeake Bay     

Thomas G. Wolaver  Joseph C. Zieman  Richard Wetzel  Ken L. Webb 《Estuarine, Coastal and Shelf Science》1983,16(3):321-332

A 22-month study was conducted to determine the exchange of nitrogen and phosphorus between a mesohaline vegetated marsh in the Carter's Creek area of Virginia and the surrounding estuary, focusing on the role of the vegetated marsh surface in the processing of these constituents. On an annual basis there was a removal of $\text{NH}{}_4{}^{\mathrm{+}}$, $\text{PO}{}_4{}^{\mathrm{3?}}$, $\text{NO}{}_3{}^{\mathrm{?}}$, dissolved organic nitrogen, dissolved organic phosphorus, particulate nitrogen and particulate phosphorus from the tidal water as it resided on the vegetated marsh. Only nitrite was transported from the marsh to the estuary. Most of the nitrogen and phosphorus species showed distinct seasonal trends with respect to the direction of transport except nitrate and orthophosphate. The ammonium flux data indicates that this nutrient was removed from the inundating water during late spring and fall, with a slight release of this constituent into the tidal water during the late summer. The transport of nitrite was from the estuary to the marsh for most of the year except during the fall. The large release of this nutrient into the tidal water at this time is associated with the senescence of the marsh vegetation. There was a large removal of DON from the tidal water during the fall, while the flux of DOP was from the estuary to the marsh for most of the year except during the summer. The largest removal of particulate nitrogen and phosphorus from the tidal water occurred during the summer months when the turbidity of the tidal water was highest, especially when wave scouring of the mudflats brings material into the water column. A loss of particulate nitrogen from the marsh to the estuary was evident during the fall and winter.  相似文献   

Silicon limitation on primary production and its destiny in Jiaozhou Bay, China Ⅳ: Study on cross-bay transect from estuary to ocean     

杨东方  陈豫  高振会  张经  王凡 《中国海洋湖沼学报》2005,(1)

1 INTRODUCTION Terrestrial matter is continuously loaded into ocean by rivers and up taken by myriad organisms who would ultimately sink to the sea bottom, whichconstitutes a complete process of transferring terrestrial matter from land to sea. Among this dynamic process, diatoms are very important in theNo.1 YANG et al.: Silicon limitation on primary production and its destiny 73material cycle. Phytoplankton is a prime mover in the conversion from inorganic matter to organic in marine…  相似文献   

气候变化、火干扰与生态系统碳循环   总被引：6，自引：0，他引：6       下载免费PDF全文

胡海清  魏书精  孙龙  王明玉 《干旱区地理》2013,36(1):57-75

 随着全球变暖的日益显著,气候变化及其影响越来越受到广泛关注。火干扰作为森林生态系统碳循环的一个重要组成部分,其干扰过程是对碳的再分配过程,因而对区域乃至全球的碳循环产生重要影响。气候变化、火干扰与生态系统碳循环三者之间存在因果循环关系,正确认识气候变化与火干扰的复杂关系及双向反馈作用,以及火干扰在生态系统碳循环中的作用,这对制定科学合理的火干扰管理策略,提高生态系统管理水平,减少碳排放,促进碳增汇,减缓全球变化速率均有重要意义。从两个方面阐述了气候变化、火干扰与生态系统碳循环之间的交互作用关系：气候变化与火干扰相互影响关系及双向反馈作用,分别从气候变化对火干扰的影响及火干扰对气候变化的影响两个方面阐述了两者之间的相互影响关系;火干扰与森林生态系统碳循环的交互作用,分别从火干扰对森林生态系统碳循环的影响及模型方法在模拟火干扰对森林生态系统碳循环影响中的应用两个方面论述火干扰对森林生态系统碳循环的影响及其定量评价模型方法。目前火干扰直接碳排放的模型方法比较完善,而间接影响碳循环的模型方法并不成熟,许多方法局限于定性描述,因此,应进一步探讨集成实地测量、遥感观测和模型模拟的跨尺度火干扰对碳循环的影响研究,注重尺度的转换问题。最后,提出了气候变暖背景下火干扰管理的路径选择,以及对今后的研究方向进行了展望。  相似文献   

新疆天然矿泉水成因类型及资源远景区预测   总被引：1，自引：0，他引：1  

顾新鲁  王占和  曾永刚  杜健  丁光发 《新疆地质》2012,30(1):95-98

新疆天然矿泉水资源主要为锶、偏硅酸、碳酸、锂、锌、矿物盐6种类型,以锶水和偏硅酸水类型最多,成因类型可分为构造断裂深循环淋溶型、裂隙浅循环淋溶型、补给富集埋藏型3种,针对上述3种成因将现状矿泉划分为7种典型矿床模式,在此基础上提出并分析已形成2处矿泉水田与预测9处天然矿泉水资源远景区,对全疆天然矿泉水勘察及开发具一定指导意义.  相似文献   

Nutrient budget of a montane evergreen broad‐leaved forest at Ailao Mountain National Nature Reserve,Yunnan, southwest China     

Wenyao Liu  John E. D. Fox  Zaifu Xu 《水文研究》2003,17(6):1119-1134

Hydrological fluxes and associated nutrient budget were studied during a 2 year period (1998–99) in a montane moist evergreen broad‐leaved forest at Ailao Mountain, Yunnan. Water samples of rainfall, throughfall, and stemflow, and of surface runoff, soil water, and stream flow were collected bimonthly to determine the concentration and fluxes of nutrients. Soil budgets were determined from the difference between precipitation input (including nutrient leaching from canopy) and output via runoff and drainage. The forest was characterized by low canopy interception and surface runoff, and high percolation and stream flow. Concentrations of nutrients were increased in throughfall and stemflow compared with precipitation. Surface runoff and drainage water had higher nutrient concentrations than precipitation and stream water. Total nitrogen and NH₄⁺‐N concentrations were higher in soil water than stream water, whereas K⁺, Ca²⁺, and Mg²⁺ concentrations were lower in the former than the latter. Annual nutrient fluxes decreased with soil depth following the pattern of water flux. Annual losses of most nutrient elements via stream flow were less than the corresponding inputs via throughfall and stemflow, except for calcium, for which solute loss was greater than the inputs via precipitation. Leaching losses of that element may be compensated by weathering. Losses of nitrogen, phosphorus, potassium, magnesium, sodium, and sulphur could be replaced through atmospheric inputs. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Silicon limitation on primary production and its destiny in Jiaozhou Bay, China V： Silicon deficit process   总被引：1，自引：0，他引：1  

杨东方高振会  王培刚孙培艳 刘霜 《中国海洋湖沼学报》2005,23(2):169-175

Silicon is a necessary nutrient for diatoms, silicon uptake in diatom reproduction decreased seawater silicon content. This paper clarified the characteristics of silicon transferring in the sea, which plays an important role in phytoplankton growth, zooplankton graze and marine ecosystem. Analysis revealed that silicate is supplied by terrestrial sources, through plankton uptake, death, and eventually deposits to the sea bottom, and cannot diffuse upward. This is a general silicon deficit process. Many global marine waters showed the same silicon transfer route: land→silicon biogeochemical process→sea bottom. River flow brings abundant silicate into marine waters, silicate concentration in the waters decreased in the distance away from the river estuaries. In discussion of silicon characteristics and its transfer route, it was considered that the main factor controlling the mechanism of diatom and non-diatom red tides occurrence is silicon, and the changes in silicon source. Human activities, such as sea-route cutting by building embankment and dam, and silicon supplement by the sea, such as sandstorm, rainstorm and storm tide, have largely impaired the earth ecosystem and hugely threatened the human existence. It is suggested in this paper that man should resume the original face of the Si input into the sea to keep natural ecosystem in sustainable pattern.  相似文献   

中国区域碳循环研究进展与展望   总被引：26，自引：2，他引：24  

戴民汉  翟惟东  鲁中明  蔡平河  蔡卫君  洪华生 《地球科学进展》2004,19(1):120-130

中国陆地和海洋生态系统的区域碳循环在全球碳循环过程中占有重要地位。目前,中国陆地生态系统在全球碳循环中的地位和作用已有比较深入的研究,而中国边缘海系统碳循环研究相对薄弱。简要回顾中国碳循环（以现代过程的描述为主）的研究动态,重点阐述中国边缘海碳循环研究概况及CO2的海-气交换、有机碳循环、颗粒有机碳的输出、河流的输运等海洋碳循环过程的关键科学问题。在汇总补充及数据更新的基础上勾画了中国区域碳循环框架。我们认为,中国的区域碳循环过程尚有诸多未知量和不确定性,缺乏把陆、海、气作为一个系统的综合研究,海洋生态系统碳循环研究尤其需要加强。中国边缘海的碳循环研究应当围绕CO2的汇源过程这一碳循环的中心问题,深入开展边缘海碳的生物地球化学及其与大气CO2的耦合作用等方面的研究。  相似文献   

Effects of riparian vegetation on stream bank subaerial processes in southwestern Virginia,USA   总被引：1，自引：0，他引：1  

T. M. Wynn  S. Mostaghimi 《地球表面变化过程与地形》2006,31(4):399-413

Riparian vegetation is frequently used for stream bank stabilization, but the effects of vegetation on subaerial processes have not been quantified. Subaerial processes, such as soil desiccation and freeze–thaw cycling, are climate‐related phenomena that deliver soil directly to the stream and make the banks more vulnerable to fluvial erosion by reducing soil strength. This study compares the impact of woody and herbaceous vegetation on subaerial processes by examining soil temperature and moisture regimes in vegetated stream banks. Soil temperature and water tension were measured at six paired field sites in southwestern Virginia, USA, for one year. Results showed that stream banks with herbaceous vegetation had higher soil temperatures and a greater diurnal temperature range during the summer compared to forested stream banks. Daily average summer soil water tension was 13 to 57 per cent higher under herbaceous vegetation than under woody vegetation, probably due to evapotranspiration from the shallow herbaceous root system on the bank. In contrast to summer conditions, the deciduous forest buffers provided little protection for stream banks during the winter: the forested stream banks experienced diurnal temperature ranges two to three times greater than stream banks under dense herbaceous cover and underwent as many as eight times the number of freeze–thaw cycles. During the winter, the stream banks under the deciduous forests were exposed to solar heating and night time cooling, which increased the diurnal soil temperature range and the occurrence of freeze–thaw cycling. Study results also indicated that freeze–thaw cycling and soil desiccation were greater on the upper stream bank due to thermal and moisture regulation of the lower bank by the stream. Therefore, subaerial erosion and soil weakening may be greater on the upper stream banks. Additional research is needed on the influence of subaerial processes on both subaerial and fluvial erosion. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

热带雨林的碳循环及其意义   总被引：2，自引：1，他引：2  

张洪波  管东生  郑淑颖 《热带地理》2001,21(2):178-182

热带雨林的碳循环及其在全球碳循环中的作用，已经成为当前的热点研究问题，热带雨林的碳循环包括植物的固碳作用、归还作用和再利用、流失及贮存三个过程，并具有周期短、贮存量大、复杂性及封闭性强的特点，而且热带雨林的碳循环对全球碳循环、全球变化、生态系统、环境和可持续发展以及人类本身有巨大影响，但是由于热带林地的土地利用每年造成相当大的碳净释放，并带来一系列的环境问题，因此深入开展对热带雨林的研究，以及合理利用、开发和保护，实现热带雨林和可持续发展意义十分重大。  相似文献