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Yunquan Li Silin Wu Shi Shu Yiyan Lv Yan Cui 《Marine Georesources & Geotechnology》2020,38(5):604-610
AbstractWith the growing demand for underwater refill engineering, the construction technology of implementing fluidized solidification in underwater pouring has recently received increased attention. However, the environmental impact of underwater casting on surrounding water bodies, especially when the silt is polluted, is still unclear. In this study, a simulated underwater pouring test and a static immersion release test were conducted separately to study the quality of the surrounding water during and after pouring. The results showed that fluidized-solidified silt casting could increase the pH of the surrounding water, even after the pouring had stopped, by approximately 1.0 and the turbidity could reach 200 NTU. No diffusion of Zn and Cu into the surrounding water was observed and while Ni and Cr exhibited slight diffusion, this was at a level well below international water quality standard. During construction, reducing the distance from the seafloor to the bottom of the pouring catheter could reduce the level of pollution. After construction, the use of neutral solidified materials can effectively reduce the pH of the surrounding water and the potential risk of heavy metal dissolution. 相似文献
64.
近年来的研究指出红树林在海岸带碳固定和碳储存方面发挥着重要的作用。尽管印度尼西亚的红树林面积在全球占很大的比重,对于该地区红树林的有机碳储量和土壤有机碳来源的认识仍有限。本研究调查了印度尼西亚北苏拉威西海洋型的Wori红树林中生态系统有机碳储量及其空间分布特征,以及土壤有机碳的来源,以期加深该地区红树林“蓝碳”功能的认识。研究结果显示,Wori红树林0-50cm深度土壤中有机碳储量为15.4 kg/m2,占生态系统碳储量的主要部分(65%)。红树植物生物量和生态系统碳储量分别为8.3 kg/m2和23.7 kg/m2。土壤有机碳储量在不同离岸距离的采样站位中未表现出显著的空间分布差异,而生物量碳储量则在外滩最高。13C稳定同位素分析结果表明红树林土壤中蓄积的有机碳主要来源于红树林有机质,而潮水中的悬浮有机质和红树林外缘的海草并不构成红树林土壤有机碳的重要来源,它们的贡献者都低于20%。研究结果进一步证实了热带地区海洋型红树林湿地在碳储存以及红树植物对碳固定方面的重要性。 相似文献
65.
Weiwei Chen Shichun Zhang Quansong Tong Xuelei Zhang Hongmei Zhao Siqi Ma Aijun Xiu Yuexin He 《中国地理科学(英文版)》2018,28(5):836-850
Northeast China experiences severe atmospheric pollution, with an increasing occurrence of heavy haze episodes. However, the underlying forces driving haze formation during different seasons are poorly understood. In this study, we explored the spatio-temporal characteristics and causes of haze events in Northeast China by combining a range of data sources(i.e., ground monitoring, satellite-based products, and meteorological products). It was found that the ‘Shenyang-Changchun-Harbin(SCH)'city belt was the most polluted area in the region on an annual scale. The spatial distribution of air quality index(AQI) values had a clear seasonality, with the worst pollution occurring in winter, an approximately oval-shaped polluted area around western Jilin Province in spring, and the best air quality occurring in summer and most of the autumn. The three periods that typically experienced intense haze events were Period I from mid-October to mid-November(i.e., late autumn and early winter), Period II from late-December to February(i.e., the coldest time in winter), and Period III from April to mid-May(i.e., spring). During Period I, strong PM_(2.5) emissions from seasonal crop residue burning and coal burning for winter heating were the dominant reasons for the occurrence of extreme haze events(AQI 300). Period II had frequent heavy haze events(200 AQI 300) in the coldest months of January and February, which were due to high PM_(2.5) emissions from coal burning and vehicle fuel consumption, a lower atmospheric boundary layer, and stagnant atmospheric conditions. Haze events in Period III, with high PM_(10) concentrations, were primarily caused by the regional transportation of windblown dust from degraded grassland in central Inner Mongolia and bare soil in western Jilin Province. Local agricultural tilling could also release PM_(10) and enhance the levels of windblown dust from tilled soil. Better control of coal burning, fuel consumption, and crop residue burning in winter and autumn is urgently needed to address the haze problem in Northeast China. 相似文献
66.
为了确定山西台网基于“山西2015速度模型”的相对固定的定位方法,选择2010~2016年最大空隙角小于45°、参与定位台站数大于40的103个地震事件,分别采用单纯形法、Hypo2000、Hyposat结合PTD等3种方法重新测定。结果显示,单纯形法和Hyposat结合PTD测定的残差以及网缘地震的震中距两方面均优于Hypo2000;在震源深度方面,Hyposat结合PTD的结果较为可信。综合分析认为,基于“山西2015速度模型”定位地震时,山西台网应固定使用Hyposat结合PTD的方法。 相似文献
67.
深弹发射装置安装在甲板部位,使用环境恶劣,过去均采用传统的试验方法进行环境适应性考核。最近几年,随着三维设计的广泛应用,仿真技术也开始发挥作用,以发射装置接线箱的冲击响应为例,介绍仿真技术在发射装置环境适应性分析中的应用。通过案例分析可知,仿真分析对于发现机械结构设计中的薄弱环节还是非常有效的,它突破了环境试验受限于试验样机和特定环境条件的限制,可以在较短的时间内得到仿真结果,对装备模型进行及时修正。 相似文献
68.
LIU Yong ) ) XIAN Weiwei ) ) Key Laboratory of Marine Ecology Environmental Sciences Institute of Oceanology Chinese Academy of Sciences Qingdao P. R. China ) College of Fisheries Ocean University of China Qingdao P. R. China 《中国海洋大学学报(英文版)》2009,8(2)
Growth and energy budget of the polychaete, Neanthesjaponica, at various temperatures (17, 20, 23, 26 and 29 ℃) were investigated in this study. The growth, as indicated by final dry weight and specific growth rate (SGR), increased with increasing temperature, with the maximum level at 26℃, and then decreased significantly at 29℃. A similar trend was observed in feeding rate, food conversion efficiency (FCE) and apparent digestive rate (ADR). However, no significant differences were detected in ADR among all the temperature treatments. In the pattern of energy allocation, faeces energy was only a small component of energy budget and had little influence on the proportion of food energy allocated to growth. The metabolic energy accounted for a large portion of energy intake for each temperature treatment. The nitrogen excretion was appreciable with changing temperature. The two expendi-ture terms (respiration energy and excretion energy) in energy budget were the major factors influencing the proportion of food en-ergy allocated to growth. These results revealed that temperature affected the growth of N. japonica mainly by influencing feeding rate and FCE. In addition, regression equations describing the relationship between feeding rate, faecal production, SGR, FCE and temperature were obtained. The optimum temperatures for feeding rate, FCE and SGR were estimated at 25.01 ℃, 24.24℃ and 24.73 ℃, respectively, from the regression equations. 相似文献
69.
地图是人们出行的可靠向导,学习地理知识的必需工具,是政府领导管理决策的重要依据.随着经济社会的发展,人们对地图的需求越来越旺盛.但地图不能任意编制出版的,它具有严格的法定性. 相似文献
70.
????1992??11???2007??5?μ???????????????????????????仯???????????????1???????24~42???μ???????Я???????????ENSO?????2??SLA_2442?????????????????????????????????????????????????????????????????3?????????У????????????SLA_2442?????????·??????O???Σ??????????????,??γ????????λ??????9.86??N??8??S?????? 相似文献