南海涠洲岛区现代沉积环境和沉积作用演化   总被引：9，自引：0，他引：9  

王国忠  全松青 《海洋地质与第四纪地质》1991,11(1):69-82

涠洲岛区沉积环境的演化导致陆源碎屑沉积作用转化为礁源和陆源的混合沉积作用,并将向纯礁源碳酸盐沉积作用方向转化;其主要控制因素是陆源碎屑供应量.陆源沉积和礁源沉积之间可以互相制约,沉积环境和沉积作用可以互为因果.文中还指出涠洲岛区的沉积组分特征和南海北部礁坪沉积组分随纬度变化的规律.  相似文献   

Uptake and distribution of N, P and heavy metals in three dominant salt marsh macrophytes from Yangtze River estuary, China   总被引：4，自引：0，他引：4  

Quan WM  Han JD  Shen AL  Ping XY  Qian PL  Li CJ  Shi LY  Chen YQ 《Marine environmental research》2007,64(1):21-37

We examined the variation in aboveground biomass accumulation and tissue concentrations of nitrogen (N), phosphorus (P), copper (Cu), zinc (Zn) and lead (Pb) in Phragmites australis (common reed), Spartina alterniflora (salt cordgrass), and Scirpus mariqueter throughout the growing season (April-October 2005), in order to determine the differences in net element accumulation and distribution between the three salt marsh macrophytes in the Yangtze River estuary, China. The aboveground biomass was significantly greater in the plots of S. alterniflora than in the plots of P. australis and S. mariqueter throughout the growing season (P<0.05). In August, the peak aboveground biomass was 1246+/-89 gDW/m(2), 2759+/-250 gDW/m(2) and 548+/-54 gDW/m(2) for P. australis, S. alterniflora and S. mariqueter, respectively. The concentrations of nutrients and heavy metals in plant tissues showed similar seasonal patterns. There was a steady decline in element concentrations of the aboveground tissues from April to October. Relative element concentrations in aboveground tissues were at a peak during the spring sampling intervals with minimum levels during the fall. But the concentrations of total nitrogen and total phosphorus in the belowground tissues were relatively constant throughout growing season. Generally, trace metal concentrations in the aboveground tissues of S. mariqueter was the highest throughout the growing season, and the metal concentrations of S. alterniflora tissues (aboveground and belowground) were greater than those of P. australis. Furthermore, the aboveground pools of nutrients and metals were consistently greater for S. alterniflora than for P. australis and S. mariqueter, which suggested that the rapid replacement of native P. australis and S. mariqueter with invasive S. alterniflora would significantly improve the magnitude of nutrient cycling and bioavailability of trace metals in the salt marsh and maybe transport more toxic metals into the water column and the detrital food web in the estuary.  相似文献   

Spatial-temporal pattern and population driving force of land use change in Liupan Mountains region, southern Ningxia, China   总被引：3，自引：0，他引：3  

Bin Quan  M. J. M. Römkens  Jianjun Tao  Bicheng Li  Chaokui Li  Guanghui Yu  Qichun Chen 《中国地理科学(英文版)》2008,18(4):323-330

The Liupan Mountains is located in the southern Ningxia Hui Autonomous Region of China, which forms an important dividing line between landforms and bio-geographic regions. The populated part of the Liupan Mountains region has suffered tremendous ecological damages over time due to population pressure, excessive demand and inappropriate use of agricultural land resources. In this paper, datasets of land use between 1990 and 2000 were obtained from Landsat TM imagery, and then spatial models were used to characterize landscape conditions. Also, the relationship between the population density and land use/cover change （LUCC） was analyzed. Results indicate that cropland, forestland, and urban areas have increased by 44,186ha, 9001ha and 1550ha, respectively while the grassland area has appreciably decreased by 54,025ha in the study period. The decrease in grassland was most notable. Of the grassland lost, 49.4% was converted into cropland. The largest annual land conversion rate in the study area was less than 2%. These changes are attributed to industrial and agricultural development and population growth. To improve the eco-economic conditions in the study region, population control, urbanization and development of an ecological friendly agriculture were suggested.  相似文献   

广东沿海牡蛎体的麻痹性毒素与评价     

杨美兰  林燕棠  全桂英 《广东海洋大学学报》1999,(3)

根据１９９０～１９９７ 年间广东沿海１７ 个采样点的牡蛎体的麻痹性毒素检测数据,阐述了广东沿海三个岸段牡蛎体中的麻痹性毒素的含量水平、地理分布、季节差异以及麻痹性毒素在牡蛎体中的分布。为我国沿海麻痹性贝类毒素中毒事件的防治提供基础数据。  相似文献   

中国历次极地考察航线及破冰船航行特征分析(1984-2019)     

艾松涛  陈一凡  桂大伟  张汝诚  沈权  单学武 《测绘地理信息》2021,46(3):1-9

1984-2019年,中国共有7艘考察船38次远赴南北两极开展科学考察活动,其中南极29航次,北极9航次,累计航程160万km.重点分析了"雪龙"号破冰船的航行特征参数,并结合GPS、机舱、罗经等多源数据,建立了破冰船航行状态分类识别模型,进而研发了破冰船的经停港口和停靠极地站点的识别模型.运用该模型对以往极地考察航次...  相似文献   

Composition of fish communities in an intertidal salt marsh creek in the Changjiang River estuary,China     

全为民  倪勇  施利燕  陈亚瞿 《中国海洋湖沼学报》2009,27(4):806-815

Fish communities in a (third-order) intertidal creek in Dongtan marsh in the Changjiang (Yangtze) River estuary were investigated seasonally for one year. A total of 1 996 fish specimens (10 967.8 g) comprising 26 species and 15 families were collected. Abundances of fish communities in the intertidal salt marsh creek were primarily dominated by Boleophthalmus pectinirostris (19.8%), Collichthys lucidus (18.6%), Periophthalmus magnuspinnatus (18.2%), Liza haematocheilus (17.9%), and secondarily by Mugilogobius abei (8.5%), L. carinatus (7.2%), Odontamblyopus lacepedii (4.3%), and Acanthogobius ommaturus (3.9%); another 18 species were present only occasionally. Non-MDS ordination and SIMPER analysis indicated that there were two fish communities in the intertidal salt marsh creek. In spring, the communities were dominated by B. pectinirostris, P. magnuspinnatus, C. lucidus and M. abei; in summer, autumn, and winter by L. haematocheilus, L. carinatus, A. ommaturus and O. lacepedii. Some species showed strong habitat selection; L. carinatus and P. magnuspinnatus were distributed mainly in the upper and middle creek, while B. pectinirostris, M. abei and O. lacepedii inhabited the middle and lower creek. The study indicated that the salt marshes of the Changjiang River estuary are an important nursery and feeding habitat for many fishes and should be protected.  相似文献   

蜀南地区龙马溪组页岩气工业建产区游离气和孔隙度下限讨论     

饶权  康永尚  黄毅  赵群  王红岩 《现代地质》2021,35(4):1054-1064

游离气作为页岩气重要赋存形式之一,决定了页岩气的开发潜力及经济效益.以蜀南地区龙马溪组页岩为例,结合X-射线衍射、岩石有机碳、储层物性、测井解释及生产测试等资料,对比分析了四川盆地及周缘页岩游离气含量与测试日产气量的关系,初步提出了工业建产区页岩游离气含量下限,并从烃源、储集及保存等方面对页岩游离气含量主控因素进行了系...  相似文献   

辽宁凌源牛营子盆地辽凌地1井北票组生烃潜力分析     

宗文明  孙求实  李晓海  郜晓勇  李永飞  石蕾  熊荃 《地质与资源》2021,30(3):350-356

通过岩石热解、饱和烃色谱-质谱、镜质体反射率等分析测试,对辽西牛营子盆地辽凌地1井侏罗系北票组烃源岩的有机质丰度、类型及成熟度进行了详细分析,综合评价了其生烃潜力.研究结果表明,侏罗系北票组有机碳含量分布在0.75％-37.9％,平均值为11.68％,有机质类型为Ⅲ型和Ⅱ2型,镜质体反射率R0主要分布于0.57％-0....  相似文献   

2006年川渝两次久旱转雨过程对比分析   总被引：9，自引：0，他引：9  

汪丽  青泉  谢娜  徐琳娜 《气象》2007,33(4):53-57

利用NCEP再分析资料、T213分析资料对解除2006年川渝特大高温伏旱的两次降温、降雨过程进行物理量诊断分析。结果表明：500hPa环流形势发生转变,高空冷平流及地面冷空气的入侵对暴雨的启动至关重要。低层偏南暖湿气流的加强及风速脉动对暴雨的发生发展有重要作用;850hPa水汽辐合,高层辐散及上升运动的加强与雨强和雨区有较好的对应关系。  相似文献   

专家分类器在京白梨气候区划中的应用   总被引：2，自引：0，他引：2  

权维俊  赵新平  郭文利  叶彩华  唐广 《气象科技》2007,35(6):849-852

根据气候和地形等因子,采用专家分类器方法对北京市的京白梨种植区进行了农业气候区划。结果表明:平谷、密云、怀柔、昌平、门头沟和房山的浅山区为京白梨的适宜种植区。与其他的区划方法相比,专家分类器方法在农业气候区划中具有较突出的先进性和实用性,它能充分地将专家的知识、经验和科研成果应用到农业气候区划中,从而得到较客观和全面的区划结果。  相似文献