The particle fluxes in sediment traps from Niulang Guyot area in the Northwest Pacific Ocean     

Xiuwu Sun  Jinmin Chen  Baohong Chen  Cai Lin  Yang Liu  Jiang Huang  Zhong Pan  Kaiwen Zhou  Qing He  Fangfang Kuang  Hui Lin 《海洋学报(英文版)》2022,41(11):34-44

The flux of settling particles in the ocean has been widely explored since 1980s due to its important role in biogenic elements cycling, especially in the transport of particulate organic carbon (POC) in the deep sea. However, research in the seamount area of the oligotrophic subtropical Northwest Pacific Ocean is lacking. In this work, two sediment traps were deployed at the foot and another two at the hillside of Niulang Guyot from August 2017 to July 2018. The magnitude and composition of particle fluxes were measured. The main factors influencing the spatial variations of the fluxes were evaluated. Our results indicated a low particulate flux from Niulang Guyot area in the Northwest Pacific Ocean, reflecting low primary productivity of the oligotrophic ocean. The total mass flux (TMF) decreased from 2.57 g/(m2·a) to 0.56 g/(m2·a) with increasing depth from 600 m to 4 850 m. A clear seasonal pattern of TMF was observed, with higher flux in summer than that in winter. The peak flux of 26.52 mg/(m2·d) occurred in August at 600 m, while the lowest value of 0.07 mg/(m2·d) was shown in February at 4 850 m. The settling particles at the deep layers had similar biochemical composition, with calcium carbonate (CaCO₃) accounting for up to 90%, followed by organic matter and opal, characteristics of Carbonate Ocean. The POC flux decreased more rapidly in the twilight layer because of faster decomposition, remineralization, and higher temperature. A small fraction of POC was transported into the deep ocean by biological pump. Particle fluxes were mainly controlled by the calcareous ballasts besides the primary productivity of the surface water. The advection may be another important factor affecting the flux in the seamount area. The combination of settled matters rich in foraminiferal tests with topography and currents may be the reason for regulating the local abundance of benthos on seamounts. Our results will fill in the knowledge gap of sedimentation flux, improve the understanding of ecosystem in Niulang Guyot area, and eventually provide data support for the optimization of regional ecological modeling.  相似文献   

Long-term changes of phytoplankton community in Xiagu waters of Xiamen, China   总被引：2，自引：0，他引：2  

CHEN Baohong  XU Zhuhu  ZHOU Qiulin  CHEN Changping  GAO Yahui  YANG Shengyun  JI Weidong 《海洋学报(英文版)》2010,29(6):104-114

Long-term changes of phytoplankton community by water sampling method in Xiagu Sea waters of Xiamen, China, were investigated in this study. Species composition of the phytoplankton community in these waters changed greatly since the 1950s. The numbers of Dinophyta species increased significantly, although Bacillariophyta species are generally dominant. The succession of dominant species in phytoplankton community is obvious:large-size dominant species such as Biddulphia sinensis of the 1950s were gradually replaced by small-size ones such as Cyclotella striata and Nitzschia closterium, and species that still maintain dominant such as Skeletonema costatum are also small ones, leading the whole phytoplankton community of smaller size. Cell density of phytoplankton community increased greatly, among which cell density of the most dominant species Skeletonema costatum have been increasing in exponent function. Margalef index of phytoplankton community decreased, indicating decline of biodiversity of the community, and dominant character of Skeletonema costatum increased. Generally, the structure of the entire phytoplankton community is becoming more and more singular and unstable, which makes the occurrence of red tides more frequent. The succession in the phytoplankton community is related to the long-term changes in marine environment, influenced by human activities and global climate changes, especially the increases of nutrient content.  相似文献   

Nutrient and eutrophication characteristics of the Dongshan Bay,South China   总被引：1，自引：0，他引：1  

陈宝红  暨卫东  周开文  贺青  傅婷婷 《中国海洋湖沼学报》2014,32(4):886-898

We recorded NO 3-N, NO 2-N, NH 4-N, PO 4-P, SiO 3-Si, salinity, and temperature data at 10 stations in the Dongshan Bay in May, June, July, August, October, and November 2008, analyzing nutrient and eutrophication characteristics. The mean concentration of dissolved inorganic nitrogen(DIN) was 0.30–0.40 mg/dm 3; generally, NO 3-N was the main form in most areas. The mean concentrations of PO 4-P and SiO 3-Si were 0.040–0.060 mg/dm 3 and 1.00–1.50 mg/dm 3, respectively. We proved that the majority of the SiO 3-Si in the Dongshan Bay came from the Zhangjiang River, with some coming from the Bachimen Strait. DIN originated from both the Zhangjiang River and the Bachimen Strait. Most PO 4-P originated from the Bachimen Strait, and some came from the Zhangjiang River. We found that P was an overall limiting factor to the phytoplankton community in most of the Dongshan Bay, and that Si and N were in surplus. However, near the Bachimen Strait Si became a limiting factor, especially for diatoms, while P and N were in comparative surplus. We used a potential eutrophication assessment method to analyze eutrophication, and showed that the most serious eutrophication occurred near the Zhangjiang River estuary and near the Bachimen Strait. In 2008, DIN levels were four times higher than that in 1988; PO 4-P levels were threefold higher, while SiO 3-Si was approximately double. Dissolved nutrients increased between 1988 and 2008. DIN increased at the greatest rate comparing to PO 4-P and SiO 3-Si, thus the N/P and N/Si mol ratios increased. Further studies on the effects of high DIN concentrations on the phytoplankton communities and marine ecosystems of the Dongshan Bay are needed.  相似文献   

Effect of SO on 1,1,1‐Trichloroethane Degradation by Fe0 in Aqueous Solution     

Jie Yu  Wenxia Liu  Aibin Zeng  Baohong Guan  Xinhua Xu 《Ground water》2013,51(2):286-292

Sulfate in groundwater has been previously shown to change the reactivity of Fe⁰ in permeable reactive barriers for reducing chlorinated organics. To better understand the effect and mechanism of SO, the degradation of 1,1,1‐trichloroethane (TCA) by Fe⁰ in unbuffered aqueous solutions with and without SO was investigated. In a Fe⁰‐TCA‐H₂O system with initial pH of 2.0 to 10.0, the maximum removal rate of TCA was achieved at the initial pH 6.0 with pseudo‐first‐order constant K_obs 9.0 × 10^?3/min. But in a Fe⁰‐TCA‐Na₂SO₄‐H₂O system, the removal rate of TCA decreased remarkably with a reduction in K_obs to 1.0 × 10^?3/min, and the pH varied from 6.0 to 9.6, indicating an inhibition of TCA dehydrochlorination by SO. Sulfate remarkably inhibited TCA degradation via changing the route of Fe⁰ dissolution. It accelerated the dissolution of Fe⁰ and transformed the intermediate form Fe(OH)_ads to Fe₂(SO₄)_ads, which weakened the affinity between Fe and TCA, and thus depressed the degradation of TCA by Fe⁰.  相似文献   

玉米、平菇、紫木耳立体种植技术研究     

Peng Baohong  Huang Yan  Hu Yumei  Zou Jun 《河南气象》2007,(Z1)

为提高玉米产量及充分利用玉米生长过程中的温、湿、光等自然资源,1996-1998年在固始县进行了玉米、平菇、紫木耳套种试验,结果表明,玉米、平菇、紫木耳大田立体种植,可使三者间适宜生态因子互惠形成,单位面积积累生物量大幅增长,较传统种植方式经济效益提高10倍以上。  相似文献   

豫南稻区小麦产量及其构成因素的气候生态评价   总被引：2，自引：0，他引：2       下载免费PDF全文

彭保宏  胡玉梅赵辉 贾涛 《气象与环境科学》2007,30(B09):133-135

从农业气候生态角度分析了影响豫南稻区小麦产量及其构成因素的气候因子，结果表明，对豫南稻区小麦生产影响最大的气候因子是涝灾。由于降水冬前比冬后变化大，常出现生育前期旱涝和中后期湿害。因此，建议在选用小麦品种时，一要注重早熟性，二要注意产量三要素协调、丰产性好，三要有配套的耕作栽培技术。  相似文献   

青海省湟水盆地全新世活动断裂分布及其活动特征研究   总被引：5，自引：0，他引：5       下载免费PDF全文

涂德龙  王赞军  曾包红  高强 《地震工程学报》1998,20(4):83-90

在详细的航卫片解译地震地质调查,古地震与历史地震研究的基础上,向人们展示了湟水构造盆地全新世断层的活动图像,对地震活动作出趋势性预测,并且发现,盆地东部为一地壳稳定性较差的活动构造块体,应引起地震工作的足够重视。  相似文献   

Katabatic Flow Structures Indicative of the Flux Dissimilarity for Stable Stratification     

Guo  Xiaofeng  Yang  Wei  Gao  Zhiqiu  Wang  Linlin  Hong  Jinkyu  Ding  Baohong  Zhao  Long  Zhou  Degang  Yang  Kun 《Boundary-Layer Meteorology》2022,182(3):379-415

Boundary-Layer Meteorology - Based on observations over an alpine glacier, we investigate the turbulent flux dissimilarity between momentum and sensible heat transfer in a stably stratified...  相似文献   

关于地壳中存在大规模虚空区的问题   总被引：1，自引：0，他引：1  

邱泽华  张宝红 《地质科学》2007,42(1):58-69

地壳中存在大规模的虚空区。几乎所有破坏性的大地震都造成了大规模的地面下沉,正是因为虚空区的存在才使这种下沉成为可能;震碛岩的C单元则是这种地面沉陷现象的地质记录。虚空区的基本特点是其内部的实际垂向压力小于静压力。构造运动导致的这种垂向压力与周围压力之差,将使虚空区的岩石发生扩容。科拉半岛上超深钻探发现大量含自由水的裂隙带,证实了地壳中虚空区的存在。一般地说,可以通过探查地壳中的低速层来发现和研究虚空区。  相似文献   

用于土地变更调查的GPS-PDA精度研究     

冯宝红  李明峰 《现代测绘》2006,29(6):20-23

本文研究了M型GPS-PDA整机精度的测试方法。通过实测数据分析，得出了该型接收机的静态基线测量、后处理准动态测量、事后RTK面积测量的精度及基线长度与数据采集时间的关系。表明该型GPS-PDA数据采集设备的各项性能指标良好，完全能满足1：1万底图的土地变更调查的精度要求。  相似文献