Magnetic characteristics of surface sediments of Liaodong Bay,China     

Wang  Shuang  Wang  Yonghong  Liu  Jian  Yu  Yiyong 《中国海洋大学学报(英文版)》2015,14(3):407-416

Analysis of magnetic properties of marine surface sediments has been gradually proved to be one of the effective means for researching the source of marine sediments. In this paper, samples from 39 sit...  相似文献   

Improved coastal wetland mapping using very-high 2-meter spatial resolution imagery     

《International Journal of Applied Earth Observation and Geoinformation》2015

Accurate wetland maps are a fundamental requirement for land use management and for wetland restoration planning. Several wetland map products are available today; most of them based on remote sensing images, but their different data sources and mapping methods lead to substantially different estimations of wetland location and extent. We used two very high-resolution (2 m) WorldView-2 satellite images and one (30 m) Landsat 8 Operational Land Imager (OLI) image to assess wetland coverage in two coastal areas of Tampa Bay (Florida): Fort De Soto State Park and Weedon Island Preserve. An initial unsupervised classification derived from WorldView-2 was more accurate at identifying wetlands based on ground truth data collected in the field than the classification derived from Landsat 8 OLI (82% vs. 46% accuracy). The WorldView-2 data was then used to define the parameters of a simple and efficient decision tree with four nodes for a more exacting classification. The criteria for the decision tree were derived by extracting radiance spectra at 1500 separate pixels from the WorldView-2 data within field-validated regions. Results for both study areas showed high accuracy in both wetland (82% at Fort De Soto State Park, and 94% at Weedon Island Preserve) and non-wetland vegetation classes (90% and 83%, respectively). Historical, published land-use maps overestimate wetland surface cover by factors of 2–10 in the study areas. The proposed methods improve speed and efficiency of wetland map production, allow semi-annual monitoring through repeat satellite passes, and improve the accuracy and precision with which wetlands are identified.  相似文献   

The use of time-series data in the assessment of macrobenthic community change after the cessation of sewage-sludge disposal in Liverpool Bay (UK)     

Whomersley P  Schratzberger M  Huxham M  Bates H  Rees H 《Marine pollution bulletin》2007,54(1):32-41

Sewage sludge was disposed of in Liverpool Bay for over 100 years. Annual amounts increased from 0.5 million tonnes per annum in 1900 to approximately 2 million tonnes per annum by 1995. Macrofauna and a suite of environmental variables were collected at a station adjacent to, and a reference station distant from, the disposal site over 13 years, spanning a pre- (1990-1998) and post- (1999-2003) cessation period. Univariate and multivariate analyses of the time-series data showed significant community differences between reference and disposal site stations and multivariate analyses revealed station-specific community development post-disposal. Temporal variability of communities collected at the disposal station post-cessation was higher than during years of disposal, when temporally stable dominance patterns of disturbance-tolerant species had established. Alterations of community structure post-disturbance reflected successional changes possibly driven by facilitation. Subtle faunistic changes at the Liverpool Bay disposal site indicate that the near-field effects of the disposal of sewage sludge were small and therefore could be considered environmentally acceptable.  相似文献   

Estrogenic activity in sediments contaminated by nonylphenol in Tokyo Bay (Japan) evaluated by vitellogenin induction in male mummichogs (Fundulus heteroclitus)     

Kurihara R  Watanabe E  Ueda Y  Kakuno A  Fujii K  Shiraishi F  Hashimoto S 《Marine pollution bulletin》2007,54(9):1315-1320

Estrogenic activity was determined in sediments collected from Tokyo Bay. Sampling was performed at five stations including the site near the sewage treatment plant. The most estrogenic sediment collected near the sewage treatment plant was fractionated into ten fractions using normal-phase high-performance liquid chromatography. Chemical analysis was carried out for each fraction and nonylphenol (NP, 20,700 ng g⁻¹ dry wt) was detected at a higher concentration than estron (2.39 ng g⁻¹ dry wt) and 17β-estradiol (<0.7 ng g⁻¹ dry wt). Furthermore, each fraction was administered to male mummichogs (Fundulus heteroclitus), and vitellogenin (Vtg) was measured after two weeks. The induction of Vtg was observed; this estrogenic potency could be attributed to the NP content in this fraction. This is the first report to suggest that the high NP concentration in the sediments from Tokyo Bay has the potential to induce Vtg in wild fish.  相似文献   

Lipid biomarkers in suspended particles from a subtropical estuary: assessment of seasonal changes in sources and transport of organic matter   总被引：1，自引：0，他引：1  

Xu Y  Jaffé R 《Marine environmental research》2007,64(5):666-678

Temporal and spatial variations in the composition of particulate organic matter (POM) from Florida Bay, USA were examined. The predominance of short-chain homologues for n-alkanes, n-alcohols and n-fatty acids as well as relatively high abundance of C(27) and C(28) sterols suggested that an autochthonous/marine source of OM was dominant bay-wide. Several biomarker proxies such as P(aq) [(C(23)+C(25))/(C(23)+C(25)+C(29)+C(31)) n-alkanes], short/long chain n-alkanes, (C(29)+C(31)) n-alkanes and taraxerol indicated a spatial shift in OM sources, where terrestrial OM rapidly decreased while seagrass and microbial OM markedly increased along a northeastern to southwestern transect. Regarding seasonal variations, POM collected during the dry season was enriched in terrestrial constituents relative to the wet season, likely as a result of reduced primary productivity of planktonic species and seagrasses during the dry season. Principal component analysis (PCA) classified the sample set into sub-groups based on PC1 which seemed to be spatially controlled by OM origin (terrestrial-mangrove vs. marine-planktonic/seagrass). The PC2 seemed to be more seasonally controlled suggesting that hydrological fluctuations and seasonal primary productivity are the drivers controlling the POM composition in Florida Bay.  相似文献   

渤海湾西北岸1974～2010年逐年填海造陆进程分析   总被引：11，自引：1，他引：10  

朱高儒  许学工 《地理科学》2012,(8):1006-1012

自20世纪70年代以来,渤海湾西北岸陆续实施了大量填海工程,形成了目前中国最大的人工填海造陆区,有必要对其进行精确和连续的监测与分析。以1974～2010年逐年MSS/TM/ETM影像为主要数据源,利用RS/GIS技术,分析了研究区填海造陆的动态空间分布和数量变化特性。36 a间,研究区共填海901.7 km2,主要在滩涂和近海进行,海岸线长度从1974年的224.9 km增长到2010年的536.7 km,填海区的重心总体上从东北向西南方向迁移了26.3 km。将研究期细分为5个阶段进行深入分析发现:研究区海岸线长度增量与填海造陆规模呈正相关关系;填海利用方式经历了盐田为主→盐田和水产养殖相结合→港口和临港工业为主的发展历程;以天津港和曹妃甸港及各自的临港工业区为填海造陆中心和副中心的格局已经形成。  相似文献   

2011年1月普里兹湾埃默里冰架附近水文特征   总被引：1，自引：0，他引：1       下载免费PDF全文

严金辉  李锐祥  侍茂崇  葛人峰  孙永明 《极地研究》2012,24(2):101-109

分析“雪龙”号2011年在普里兹湾埃默里冰架外缘24个站位的CTD观测结果,发现有以下一些水文特征：普里兹湾西部,在71°E-72°E范围内,存在一个顺时针运动的中尺度涡。由于这个涡旋存在,冰架水主要扩散方向偏东,在73°30′E附近,流向东北;夏季表层水厚度,东部基本在20m,西部受中尺度涡和其他因素的影响,夏季表层水厚度深达50m左右;在50m以浅的水层内,表面以下温度会出现稍微增大现象,我们称之为逆温层,它是结冰、融冰和海冰覆盖变化造成的;在观测断面西部,在160m～200m水层内,多站出现“静力不稳定”：即上层密度大于下层,厚度有几米,平流混合扩散可能是这一不稳定现象主要原因。  相似文献   

渤海湾地区一次碰撞型海风锋天气过程的数值模拟分析   总被引：1，自引：0，他引：1  

梁钊明  高守亭  王彦 《气候与环境研究》2013,18(6):733-745

利用WRF(Weather Research and Forecasting)模式对渤海湾地区2009年9月26日一次碰撞型海风锋天气过程进行了数值模拟分析,模拟结果较好地重现了这次天气过程以及海风锋的结构和特征。结果显示,海风锋锋后是较为深厚的对流不稳定能量和水汽高值区,锋后水汽高值区的形成源于海风的堆积和往高空输送,而锋后对流不稳定能量的产生归因于抬升凝结高度和自由对流高度的降低以及平衡高度的升高,这些高度变化则源于冷湿海风给低层大气带来的降温和增湿,其中给低层大气带来的增湿是主要影响因子。对流系统与海风锋相向碰撞时,对流系统容易进入海风锋锋后触发强对流不稳定能量形成强对流运动,同时弱对流抑制为对流运动的触发提供了有利的条件,强对流运动把海风锋锋后充沛的水汽往上输送,从而造成强降水天气。另外,对流系统与海风锋碰撞后沿着海风锋锋后移动可能更有利于对流运动的发展和维持。  相似文献   

泉州湾洛阳江河口桐花树和秋茄红树植物中重金属元素的分布与富集特征   总被引：2，自引：0，他引：2  

胡恭任  于瑞莲  赵金秀  刘小进  涂湘林 《岩矿测试》2010,29(3):236-240

通过测定泉州湾洛阳江河口红树林区表层沉积物中酸提重金属元素含量及桐花树、秋茄两种红树植物各部位中重金属元素含量,分析了重金属元素在两红树植物不同部位的分布特征及其富集和迁移能力,并初步探讨了两种红树植物体内各重金属元素的主要来源。红树林区各采样点表层沉积物中重金属元素酸提量顺序为:FeMnZnPbCuCrN iCo,Cu和Pb的平均酸提量超过第一类海洋沉积物质量标准限值。同种元素在两种红树植物不同部位中的含量顺序一致:Cu为根枝叶;N i为叶根枝;Fe、Mn、Cr、Zn、Pb、Co为根叶枝。两种红树植物对N i、Cr、Cu、Zn、Fe、Mn的富集能力高于Co和Pb。秋茄对Cu、N i、Mn、Fe、Co的富集能力比桐花树略强些,而对Zn、Cr、Pb的富集能力则相对弱些;但两种植物对各元素的富集能力都达不到超富集植物的要求。两种植物对N i元素的富集能力都大于其他元素,且都集中在叶部,其他元素则主要集中在根部。除N i外,其余元素在两植物体内的迁移系数均小于1。桐花树中的Cr和秋茄中的Cu、Zn、Mn主要来源于林地沉积物,其他元素在两植物各部位均有不同的来源。  相似文献   

基于条件价值法评估罗源湾海洋生物多样性维持服务价值   总被引：4，自引：0，他引：4  

王丽  陈尚  任大川  柯淑云  李京梅  王栋 《地球科学进展》2010,25(8):886-892

海洋生物多样性维持服务指海洋中不仅生活着丰富的生物种群,还为其提供了重要的产卵场、越冬场、索饵场、避难所、栖息地等场所.基于条件价值法,于2009年8月对福建罗源湾周边城镇居民进行问卷调查,掌握当地居民对保护罗源湾生物多样性的支付意愿,进而评估罗源湾生物多样性维持服务价值.结果显示,2009年罗源湾4种珍稀生物的支付意愿为618.8元/户.2004-2008年罗源湾生物多样性维持服务价值分别为747.17万元、1 912.52万元、2 565.08万元、3 821.92万元、5 272.00万元.分析表明:家庭年收入、对保护生物的了解程度和环保意识是影响生物多样性维持服务价值的主要因素.对于保护海洋生物多样性来说,经济发展政策和环保政策都是必要的,如何做好这2个政策的平衡是政府应该关注的.  相似文献