Innovative Artificial Agro‐Ecosystems Enhance Soil Carbon Sequestration in Coastal Zones of Southeast China     

Gengmao Zhao  Xing Sun  Liu Ling  Zhaopu Liu 《洁净——土壤、空气、水》2013,41(6):581-586

Tidal flats, which are important reserved land resources, have a vital role in climate change. To evaluate the contribution of coastal saline soils to carbon sequestration, field tests were performed over a 3 year period at the Dafeng Wanggang Experimental Station in Jiangsu Province, China. Six artificial agro‐ecosystems, including wasteland (WL), freshwater fish culture (FC), Sesbania culture (SC), barley culture (BC), mixed culture of fish and Sesbania (MCFS) and mixed culture of fish and barley (MCFB), were established according to developmental processes of coastal saline soils. At the initial stage of tidal flat reclamation, the soil organic carbon (SOC) increased by 59.4 t ha^?1 in the FC system during 3 years, which was much higher than that of the WL system (40.7 t ha^?1). When the tidal flats evolved into high saline soils, the MCFS system sequestered SOC more effectively than the FC or SC systems with increases of 53.1, 16.9 and 8.3 t ha^?1, respectively. Subsequently, in the low saline soils, the maximum soil carbon sequestration was obtained in the MCFB system (35.8 t ha^?1) followed by the BC (17.5 t ha^?1) and FC (13.5 t ha^?1) systems. Therefore, proper development of tidal flats to farmland and the subsequent establishment of optimised artificial agro‐ecosystems make an important contribution to carbon sequestration and climate changes in coastal areas.  相似文献   

海南黎安港海草床碳储量评估     

杨熙  余威  何静  黄盛 《海洋科学》2022,46(11):116-125

本研究对海南黎安港海草床碳储量进行了评估,并对我国南海区近岸现存海草床总碳储量进行了估算。结果显示,黎安港海草床中海草植物碳储量、100cm深度沉积物碳储量和总碳储量分别为(179.75±102.28)Mg C、(7795.86±2923.75)Mg C和(7975.61±2907.15)Mg C;南海区近岸现存海草床总储碳量约为357008.86Mg C。研究发现,黎安港沉积物有机碳含量平均值为0.56%±0.25%,海草植物储碳密度为(1.60±0.91)Mg C·ha^-1,100 cm深度沉积物储碳密度为(69.61±26.11)Mg C·ha^-1,均明显低于全球平均值(分别为2.50%、2.52Mg C·ha^-1和139.70Mg C·ha^-1)。黎安港有些裸滩区域沉积物有机碳含量和储碳密度要高于相邻的海草生长区,鉴于海草生长区与其周边一些裸滩区域存在有机碳的交换转移,建议将海草生长区周边的一些裸滩区沉积物碳储量也纳入海草床总碳储量。  相似文献   

波流共同作用下潮滩剖面沉积物和地貌分异规律——以长江口崇明东滩为例   总被引：1，自引：0，他引：1  

刘红  何青  吉晓强  王亚  徐俊杰 《沉积学报》2008,26(5):833-843

通过对崇明东滩两个海滩剖面、表层沉积物和悬沙粒度以及同步水沙资料的分析,探讨波流共同作用下表层沉积物和地貌的分异规律。受波流共同作用的影响,表层沉积物中值粒径由破波带向两侧逐渐变细,分选由破波带向两侧逐渐变差,偏度由极正偏变为正偏,峭度由很窄尖变为宽平和中等峭度。由破波带向岸方向,流速逐渐减小,含沙量逐渐增加。悬沙和表层沉积物粒度特征的对比分析表明,潮间带上部的悬沙主要来源于破波带泥沙的再悬浮。破波带内泥沙以“波浪掀沙”引起的分选运移为主,而破波带两侧的泥沙以潮流对破波带水体的“平流输移”为主。以潮汐水位和高精度海滩剖面数据对崇明东滩微地貌类型按高程进行了新的划分。  相似文献   

基于淤积量的崇明东滩促淤围垦合理性评价     

高宇  张涛  张婷婷  王思凯  宋超  庄平 《湿地科学与管理》2017,(1):4-8

精准围垦的生态预警研究,需要从较短的时间尺度上和较集中的空间尺度上及时精准地监测滩涂的淤积量和淤积位置,这是滩涂围垦工程规划和实施的参考依据。以崇明东滩为例,结合滩涂湿地淤积量的直接测定和滩涂微地貌调查,尝试基于淤积量长期累积的相对高程评价促淤围垦的合理性。淤积量的测定结果表明:1微地形下的植被群落分带差异大到足以掩盖高程逐渐下降的梯度趋势;2潮间带和高潮滩的年均淤积速度均不足1 cm,而低潮滩的年均淤积速度达到了7 cm左右;3微地貌高程与淤积量之间呈极显著的负相关关系,呈现出两种不同的淤积机制。在此基础上,对目前以"生物促淤+物理围垦"的模式治理互花米草外来种入侵的促淤围垦进行了评价:1在快速淤涨的崇明东滩湿地中,生态系统工程师效应起着重要作用;2尽管在本研究实验区的围垦边界高程选择是合理的,但在实验区以外的围垦边界高程甚至延展到了0 m线以下,这是滩涂湿地过度围垦的直接证据之一;3与过去几次大围垦所不同的是,本次围垦范围选择的留一半、围一半的模式,一方面可以有效治理互花米草,另一方面可以预留足够的生态栖息地保留区。总之,淤积量的长期定点观测,为长江三角洲滩涂资源的动态管理和科学围垦提供了参考依据,可更客观地协调滩涂湿地保护和开发利用之间的矛盾。  相似文献   

基于遥感的腰沙海域潮滩演变趋势研究          下载免费PDF全文

吴佳乐  徐敏  刘佰琼 《海岸工程》2016,35(4):19-31

腰沙位于江苏省南通市东南侧海域,是江苏岸外辐射状沙脊南翼最大的沙洲,其滩槽地貌形态较为复杂,但潮滩和深槽均相对比较稳定,深水岸线富有。通过对1987,1995,2000,2008,2015年五个时期的卫星遥感数据和辐射沙洲地区调查资料分析,利用适合腰沙沙洲岸线演变的遥感波段组合,获得了腰沙地区20多a来岸滩典型地理特征演变的信息,结果表明:1987-2015年,腰沙潮滩内缘区围垦发展迅速,人工岸线愈加复杂。腰沙"水道—沙洲系统"组合形态总体态势呈现外缘区东侧及南侧淤涨,北侧侵蚀。小庙洪水道总体有向南偏移的趋势。潮滩南北方向在形态及演变动态上存在空间分异。  相似文献   

Comparison of two feature selection methods for the separability analysis of intertidal sediments with spectrometric datasets in the German Wadden Sea     

《International Journal of Applied Earth Observation and Geoinformation》2016

The spectral features of intertidal sediments are all influenced by the same biophysical properties, such as water, salinity, grain size or vegetation and therefore they are hard to separate by using only multispectral sensors. This could be shown by a previous study of Jung et al. (2015). A more detailed analysis of their characteristic spectral feature has to be carried out to understand the differences and similarities. Spectrometry data (i.e., hyperspectral sensors), for instance, have the opportunity to measure the reflection of the landscape as a continuous spectral pattern for each pixel of an image built from dozen to hundreds of narrow spectral bands. This reveals a high potential to measure unique spectral responses of different ecological conditions (Hennig et al., 2007).In this context, this study uses spectrometric datasets to distinguish between 14 different sediment classes obtained from a study area in the German Wadden Sea. A new feature selection method is proposed (Jeffries-Matusita distance bases feature selection; JMDFS), which uses the Euclidean distance to eliminate the wavelengths with the most similar reflectance values in an iterative process. Subsequent to each iteration, the separation capability is estimated by the Jeffries-Matusita distance (JMD). Two classes can be separated if the JMD is greater than 1.9 and if less than four wavelengths remain, no separation can be assumed. The results of the JMDFS are compared with a state-of-the-art feature selection method called ReliefF. Both methods showed the ability to improve the separation by achieving overall accuracies greater than 82%. The accuracies are 4%–13% better than the results with all wavelengths applied. The number of remaining wavelengths is very diverse and ranges from 14 to 213 of 703. The advantage of JMDFS compared with ReliefF is clearly the processing time. ReliefF needs 30 min for one temporary result. It is necessary to repeat the process several times and to average all temporary results to achieve a final result. In this study 50 iterations were carried out, which makes four days of processing. In contrast, JMDFS needs only 30 min for a final result.  相似文献   

风暴过程中潮滩悬沙浓度和悬沙输运的变化及其动力机制——以长江三角洲南汇潮滩为例   总被引：1，自引：1，他引：0  

苗丽敏  杨世伦  朱琴  史本伟  李鹏  吴创收 《海洋学报》2016,38(5):158-167

悬沙浓度是淤泥质海岸重要的环境指标。为探讨潮滩悬沙浓度和悬沙输运对风暴事件的响应过程及其动力机制,于2014年9月"凤凰"台风过境前、中、后在长江三角洲南汇潮滩进行了现场观测,获得同步高分辨率的水深、波高、近底流速和浊度剖面时间序列(9个潮周期)。结果表明,风暴中平均和最大波高、波-流联合底床剪切应力、悬沙浓度和悬沙输运率可比平静天气高数倍;风暴期间高潮位低流速阶段悬沙沉降导致近底发育数十厘米厚的浮泥层(悬沙浓度大于10 g/L)。研究认为风暴事件中淤泥质海岸悬沙浓度和悬沙输运的剧烈变化其根本动力机制是风暴把巨大能量传递给近岸水体,进而显著增大波-流联合底床剪切应力,导致细颗粒泥沙再悬浮。  相似文献   

On the sensitivity of tidal residuals off the west coast of Britain to mesh resolution     

J. Eric Jones  Alan M. Davies 《Continental Shelf Research》2007

An irregular mesh model of the west coast of Britain is used to examine the sensitivity of tidal residuals to mesh resolution in the region. Computed residuals are compared with earlier published results determined with a high resolution (1 km grid) finite difference model of the eastern Irish Sea. Initial calculations show that tidal residuals are largest in nearshore regions particularly in the vicinity of headlands. Local refinement of the mesh in these regions leads to a more detailed picture of the flow field, particularly adjacent to the coast. Although large scale offshore features of the flow can be resolved using the high resolution finite difference model, such an approach leads to a “stair case” representation of the coastal boundary with an adjacent near coastal region of spurious tidal residuals. By using an irregular mesh that follows the coast, this effect is removed. In the Mersey river region the tidal residual is resolved with a mesh resolution of 120 m, although calculations show that its distribution is particularly sensitive to small scale features of the topography. A variable mesh that can accurately represent the lateral variations in river width and details of topography in both the nearshore and estuarine environment appears essential in modelling the coastal spread of freshwater plumes from rivers and pollutants discharged into the near coastal environment.  相似文献   

放射性同位素定年技术在崇明岛潮滩沉积速率上的应用研究   总被引：1，自引：0，他引：1  

汤奇峰  黄园英  刘久臣  徐清  王晓春  谭科艳  刘晓端 《岩矿测试》2010,29(6):667-673

选取崇明岛北侧由东至西4个潮滩沉积柱,分析137Cs、226Ra和210Pb放射性比活度,应用210Pb和137Cs放射性同位素定年方法计算崇明岛潮滩沉积物沉积速率。对于东西两端,210Pb方法测得速率分别为3.08cm/a和2.34 cm/a,而137Cs测得速率分别为6.19 cm/a和2.06 cm/a。结果表明,137Cs定年方法计算出的潮滩沉积速率普遍大于210Pb方法结果;但两者反映了相同的速率规律。崇明岛主力生长方向为东和东北,西侧沉积作用相对较弱,表现出"东快西慢"的特点。沉积纵向上,1954年以来,自下而上沉积速率逐渐减缓。  相似文献   

鄂尔多斯盆地南缘下奥陶统马家沟组马六段成藏潜力分析     

白海峰  马占荣  刘宝宪 《西北地质》2010,43(1):107-114

鄂尔多斯盆地下奥陶统马家沟组马六段在盆地南缘广泛分布,从北向南厚度增大。岩性为含藻石灰岩、云斑灰岩、粉晶白云岩和颗粒白云岩。从早奥陶世华北地台南缘大地构造背景出发,分析了鄂尔多斯盆地南缘下奥陶统马家沟组马六段的沉积环境和沉积模式。综合露头剖面与井下岩心分析资料及岩性组合特征,探讨了马六段成藏要素及其空间配置关系,指出马六段以局限洼地和白云质石灰岩台坪沉积为主,局部层段发育礁滩相沉积,经后期成岩白云岩化可形成有效的白云岩储层,与上覆富含泥质的平凉组共同形成上生下储型成藏组合,具有一定的资源潜力。  相似文献