黄河下游断流对沿岸地下水形成与开发的影响     

曹剑峰  王凯军  姜纪沂  冶雪艳 《吉林大学学报(地球科学版)》2007,37(5):937-942

黄河下游河段断流对沿黄地区生态环境影响严重。以1999年为基准年,利用黄河下游侧渗补给影响带地下水系统模拟模型研究了黄河断流对黄河侧渗量及地下水循环的影响。花园口-河口断流300d,黄河侧渗量减少53.8%。夹河滩-河口全年断流,黄河侧渗量减少75.2%;断流300d,黄河侧渗量减少46.3%。泺口-河口全年断流,黄河侧渗量减少25.1%;断流300d,黄河侧渗量减少19.8%。利津-河口全年断流,黄河侧渗量减少4.7%。断流对黄河侧渗补给影响带地下水流场的形态影响较小,浅层地下水系统边界的水力性质没有改变。断流对黄河下游傍河水源地开采动态水位影响较大,但宏观上对侧渗补给影响带地下水资源不会产生较大影响。  相似文献   

导致男性不育的环境生物地球化学因素   总被引：2，自引：0，他引：2  

杨超群 《矿物岩石地球化学通报》2000,19(1):64-66

导致男性不育的主要因素有：原生(天然的)环境生物地球化学因素,包括饮用水水质,微量元素如锌和锰,人群对生物地球化学环境的适应性等等;次生(污染的)环境生物地球化学,如环境激素的影响、空气中金属微粒的污染等;环境物理因素,包含核、X射线、电磁波和热的辐射等;社会环境因素．包括不健康和不道德的生活行为,如吸烟、吸毒、酗酒、性滥交,不科学的生活方式导致的肥胖症的影响等。男性不育的防治也在中作了简要讨论。  相似文献   

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   

Lateral downslope transport and tentative sedimentary organic carbon box model in the southern Yap Trench,western Pacific Ocean     

Dong Li  Jun Zhao  Chenggang Liu  Jianming Pan  Ji Hu 《海洋学报(英文版)》2023,42(1):61-74

Sediment collapse and subsequent lateral downslope migration play important roles in shaping the habitats and regulating sedimentary organic carbon(SOC) cycling in hadal trenches.In this study,three sediment cores were collected using a human-occupied vehicle across the axis of the southern Yap Trench(SYT).The total organic carbon(TOC) and total nitrogen(TN) contents,δ¹³C,radiocarbon ages,specific surface areas,and grain size compositions of sediments from three cores were measured.We...  相似文献   

阿哈湖Fe、Mn沉积后再迁移的生物地球化学机理   总被引：18，自引：1，他引：17  

万曦  万国江  黄荣贵  普勇 《湖泊科学》1997,9(2):129-134

贵州阿哈湖是一底层滞水带季节性缺氧的中型人工湖。由于长期积累。沉积物顶部微粒悬浮层出现了Ｆｅ、Ｍｎ富集。湖底缺氧时,经生物氧化作用形成的Ｆｅ＾２＋、Ｍｎ＾２＋自沉积物向上覆水体扩散,水体Ｆｅ＾２＋浓度增高比Ｍｎ＾２＋滞后出现且超过前结束。  相似文献   

The role of biocrusts in nitrogen cycling on the tropical reef islands,South China Sea     

Lin Wang  Si Zhang  Jie Li 《海洋学报(英文版)》2021,40(4):116-126

Harboring polyextremotolerant microbial topsoil communities, biological soil crusts(biocrusts) occur across various climatic zones, and have been well studied in the terrestrial drylands. However, little is known about the functional metabolic potential of microbial communities involved in the biogeochemical processes during the early succession of biocrusts on the tropical reef islands. We collected 26 biocrusts and bare soil samples from the Xisha Islands and Nansha Islands, and applied a functional gene array(GeoChip 5.0) to reveal nitrogen(N)cycling processes involved in these samples. Both physicochemical measurement and enzyme activity assay were utilized to characterize the soil properties. Results revealed the composition of N-cycling functional genes in biocrusts was distinct from that in bare soil. Additionally, microorganisms in biocrusts showed lower functional potential related to ammonification, denitrification, N assimilation, nitrification, N fixation, and dissimilatory nitrate reduction to ammonium compared to bare soils. Although the abundance of nifH gene was lower in biocrusts, nitrogenase activity was significantly higher compared to that in bare soils. Precipitation, soil physicochemical properties(i.e., soil available copper, soil ammonia N and pH) and soil biological properties(i.e., β-glucosidase, fluorescein diacetate hydrolase, alkaline protease, urease, alkaline phosphatase, catalase and chlorophyll a) correlated to the N-cycling functional genes structure. Nitrate N and ammonia N were more abundant in biocrusts than bare soil, while pH value was higher in bare soil. Our results suggested biocrusts play an important role in N-cycling in coral sand soil, and will be helpful in understanding the development and ecological functions of biocrusts on tropical reef islands.  相似文献   

海洋沉积物/颗粒物在生源要素循环中的作用及生态学功能   总被引：2，自引：1，他引：1  

宋金明  李学刚 《海洋学报》2018,40(10):1-13

海洋沉积物/颗粒物是生源要素循环过程中的关键源与汇，沉积物/颗粒物一方面是海水生源要素的主要归宿，生源要素从溶解态经复杂的生物-化学过程转变为颗粒态，颗粒物质再沉降形成沉积物，另一方面，海洋沉积物/颗粒物经过微生物-浮游动物-底栖生物作用分解形成溶解态的生源要素，并释放到海水中再次被浮游植物利用，进入下一轮循环，所以，海洋沉积物/颗粒物具有异常重要的生态学功能。浮游植物是海水溶解态生源要素的利用者和海源颗粒态生源要素的初始形成者，浮游动物通过摄食浮游植物或其他有机颗粒物可释放出溶解态生源要素或形成更大的颗粒物，颗粒物沉降后形成的沉积物又通过底栖生物摄食-扰动-破碎等过程将颗粒生源要素释放进入水体参与再循环。生态系统不同类群的生物在颗粒生源要素的释放-沉降中所起的作用不同而又相互关联，其中浮游动物-底栖生物的摄食与代谢、微生物参与的分解过程起着非常重要的作用。所以，海洋沉积物/颗粒物生态学功能研究作为支撑海洋环境和资源的持续利用的科学基础，已成为海洋科学的前沿领域，必将获得跨越发展。  相似文献   

An extreme flood caused by a heavy snowfall over the Indigirka River basin in Northeastern Siberia     

Shunsuke Tei  Tomoki Morozumi  Shin Nagai  Shinya Takano  Atsuko Sugimoto  Ryo Shingubara  Rong Fan  Alexander Fedorov  Tuyara Gavrilyeva  Nikita Tananaev  Trofim Maximov 《水文研究》2020,34(3):522-537

Flooding is one of the greatest disasters that produces strong effects on the ecosystem and livelihoods of the local population. Flood frequency is expected to increase globally making its risk assessment an urgent issue. In spring-summer 2017, an extreme flooding occurred in the Indigirka River lowland of Northeastern Siberia that inundated a large area. In this study, the extent and climatic drivers of the flooding were determined using the results of field observations, satellite images, and climate reanalysis dataset, and its possible effects on the ecosystem were discussed. In 2017, a significant lowland area of around 16,016 km² was covered with water even in July, which was 5,217 km² (around 4% of the total area) greater than the water-covered area in 2015 when usual hydrological condition in the area was observed. The hydrographic signature obtained for the Indigirka River water level in 2017 was unusual. Although the water level rose sharply at the end of May (which was typical for the Arctic region), it did not fall afterwards and even increased again to an annual daily maximum value in the middle of July. The climate reanalysis dataset obtained for the temporal–spatial variations of snow water equivalent, snowmelt, and runoff over the lowland revealed that a large amount of snowmelt runoff in June and July 2017 produced a large water-covered area and unusually high river water levels that lasted until summer. Snow depth from winter to spring was largest in 2017 over the period from 2009 to 2017, and the surface of the lower reach of the lowland was partially covered with snow even in the end of June due to the extreme snowfall that occurred in October 2016. Such unusual hydrological conditions waterlogged most trees over the lowland, which caused serious ecosystem devastation and changes in the material cycle.  相似文献   

A portable experimental hillslope for frozen ground studies          下载免费PDF全文

Dyan L. Pratt  Jeffrey J. McDonnell 《水文研究》2017,31(24):4450-4457

Frozen ground hydrological effects on runoff, storage, and release have been observed in the field and tested in numerical models, but few physical models of frozen slopes (at scales from 1 to 15 m) exist partly because the design of such an experiment requires new engineering design for realistic whole‐slope freezing and physical model innovation. Here, we present a new freezable tilting hillslope physical model for hydrological system testing under a variety of climate conditions with the ability to perform multiple (up to 20 per year) freeze–thaw cycles. The 4 × 2 m hillslope is mobile and tiltable on the basis of a modified tri‐axle 4.88‐m (16′) dump trailer to facilitate testing multiple configurations. The system includes controllable boundary conditions on all surfaces; examples of side and baseflow boundary conditions include permeable membranes, impermeable barriers, semipermeable configurations, and constant head conditions. To simulate cold regions and to freeze the hillslope in a realistic and controlled manner, insulation and a removable freezer system are incorporated onto the top boundary of the hillslope. The freezing system is designed to expedite the freezing process by the addition of a 10,130‐KJ (9,600‐BTU) refrigeration coil to the top‐centre of the insulated ceiling. Centre placement provides radial freezing of the hillslope in a top‐down fashion, similar to what natural systems encounter in the environment. The perimeter walls are insulated with 100 mm of spray foam insulation, whereas the base of the hillslope is not insulated to simulate natural heat fluxes beneath the frozen layer of soil. Our preliminary testing shows that covers can be frozen down to ?10 °C in approximately 7 days, with subsequent thaw on a similar time frame.  相似文献   

Dissolved inorganic carbon isotopes of a typical alpine river on the Tibetan Plateau revealing carbon sources,wetland effect and river recharge     

Lu Ge  Hongbin Tan  Xi Chen  Wenbo Rao  Meitong Fan 《水文研究》2021,35(10):e14402

The Nyangqu River, the largest right bank tributary of the Yarlung Zangbo River in the Qinghai–Tibet Plateau, was representative of an alpine riverine carbon cycle experiencing climate change. In this study, dissolved inorganic carbon (DIC) spatial and seasonal variations, as well as their carbon isotopic compositions (δ¹³C_DIC) in river water and groundwater were systematically investigated to provide constraints on DIC sources, recharge and cycling. Significant changes in the δ¹³C_DIC values (from −2.9‰ to −23.4‰) of the water samples were considered to be the result of different contributions of two dominant DIC origins: soil CO₂ dissolution and carbonate weathering. Three types of rock weathering (dissolution of carbonate minerals by H₂CO₃ and H₂SO₄, and silicate dissolution by H₂CO₃) were found to control the DIC input into the riverine system. In DIC cycling, groundwater played a significant role in delivering DIC to the surface water, and DIC supply from tributaries to the main stream increased from the dry season to the wet season. Notably, the depleted δ¹³C_DIC ‘peak’ around the 88.9° longitude, especially in the September groundwater samples, indicated the presence of ‘special’ DIC, which was attributed to the oxidation of methane from the Jiangsa wetland located nearby. This wetland could provide large amounts of soil organic matter available for bacterial degradation, producing ¹³C-depleted methane. Our study provided insights regarding the role of wetlands in riverine carbon cycles and highlighted the contribution of groundwater to alpine riverine DIC cycles.  相似文献