1957—2019年厦门市马銮湾海岸线和围填海时空演变及互动关系分析

我国海湾地区高强度开发使得围填海活动频繁、岸线变化显著,分析岸线与围填海的时空动态特征以及互动关系对湾区的发展具有重要意义.运用分形维数、岸线开发利用程度指数和土地利用程度指数等方法,研究了厦门市马銮湾1957—2019年海岸线变迁和围填海的时空演变特征以及互动关系.结果表明:①1957—2019年马銮湾大陆岸线长度减...     

基于海洋生态文明建设的我国近岸海域综合治理

为持续改善海洋生态环境和提升海洋生态服务功能,进一步促进海洋生态文明建设和沿海地区可持续发展,文章梳理我国已开展的近岸海域综合治理工作内容,深入分析存在的问题,并基于目标和任务提出对策措施。研究结果表明:20世纪90年代以来,我国陆续实施一系列近岸海域综合治理项目,取得显著成效,但在整体规划、管理机制、统筹协调和科学支撑方面仍存在不足;基于近岸海域综合治理在海水质量、生态服务功能、人居环境和能力建设方面的目标和任务,应加强顶层设计、完善运行监管、坚持陆海统筹和强化基础研究。     

珠海市海岸线分类及开发利用的遥感分析

文章采用遥感解译与现场踏勘相结合的方法,开展珠海市海岸线分类及开发利用现状研究。通过遥感影像解译提取岸线数据,对砂质岸线、淤泥质岸线、基岩岸线、生物岸线、具有自然海岸形态特征和生态功能的岸线、人工岸线等岸线类型进行解译标志建立,并对岸线进行分类与统计;根据岸线分类统计结果与现场踏勘情况,对珠海市海岸线开发利用现状进行评价,并分析其存在的问题。研究表明,珠海市大陆海岸线长257.48km,其中自然岸线仅占岸线总长的17.49%,岸线开发利用强度较大且利用方式粗放,近岸海域生态压力增大,同时由于围填海导致大陆与海岛相连,海岛属性发生改变。文章最后提出加强自然岸线保护与修复、优化利用人工岸线、开展岸线动态监测、强化生态环境保护的建议,以期增强珠海市海岸线的保护与开发利用,落实自然岸线保有率,为珠海市海岸带相关规划研究和海域管理提供参考作用。     

我国海岸线退出机制的建立和完善

为加强我国海岸线资源的使用和管理,优化海岸线的开发利用和保护,促进海洋经济和资源环境的可持续发展,文章在概述海岸线退出机制的内涵及其研究和实践进展的基础上,分析该机制的建立和完善。研究结果表明:我国目前尚未形成系统和综合的海岸线退出机制,主要在法律、制度、经济和社会4个方面面临困境;应坚持绿色发展等4项原则,针对擅自改变海岸线用途等6种情形,分别采用强制退出、倒逼退出和协议退出3种模式,建立和实施海岸线退出机制;通过完善法律法规和制度体系、长效运作机制、海岸线资源再配置以及补偿措施,完善海岸线退出机制。     

对国外层序地层学研究进展的几点思考及L-H-T层序地层学

针对国际上层序地层学研究进展认为,层序地层学概念及其基础理论体系需要完善。表现为:（1）地震地层学的地震层序不同于层序地层学之沉积层序;（2）基于海陆相应用差异,1992年开始层序地层学由经典三分模式向现行四分模式转变,使得层序地层学发展更趋复杂化;（3）现行四分模式对应的基准面旋回实际上是非周期性的,与岸线迹线不相符;（4）简单介绍了基于经典三分和现行四分模式所修改的L-H-T层序地层学模式。重新定义层序为“一套成因相关的以残留最大水泛面及其相对应的不整合界面为界的相对整合的地层序列”。     

中国陆地生态系统总初级生产力VPM遥感模型估算

陆地生态系统总初级生产力(Gross Primary Productivity,简称GPP)时空格局及其变化动态的准确监测是区域碳收支研究的核心问题之一,遥感模型正在为区域碳通量监测提供更为实时、准确的模拟数据。基于中分辨率成像光谱仪(MODerate-resolution Imaging Spectroradiometer,简称MODIS)遥感数据和涡度相关碳通量观测数据发展而来的VPM模型经过10年的努力,目前已经在全球涵盖十类生态系统的21个站点上开展模型的校验与验证研究,为区域GPP的准确估算与监测奠定了方法基础。本研究构建了评估GPP区域格局的VPM模型区域模式,以空间分辨率500m、时间步长8天的MODIS卫星影像数据以及相同时空分辨率的温度与光合有效辐射数据为模型输入数据,模拟估算我国2006~2008年GPP及其空间分布格局。VPM模型模拟的中国陆地生态系统GPP年总量平均值为5.0Pg C/a,其中森林、草地、农田和灌丛生态系统分别占34%,17%,37%和12%。本研究模拟的全国GPP总量与多模型模拟的平均结果(5.40 Pg C/a)相当,但不同模型估算的各类生态系统GPP存在较大差异。本研究通过利用遥感数据对VPM模型中的关键参数(最大光能利用率)进行参数空间化,表达同一土地覆被类型内部光能利用率的空间异质性;应用目前我国准确性最为可靠的土地利用与植被数据提取土地覆被数据,首次将农业多熟种植作为单独的植被类型引入模型中,模型参数与输入数据的精度保障了模型模拟结果的可靠性。     

高能射流式液动锤低阻高效冲锤结构研究

为了对SC-86H型高能射流式液动锤冲锤结构进行优化,应用CFD动态分析,对2种不同冲锤结构的射流式液动锤模型进行了研究。计算表明：在相同输入流量下,新型冲锤结构的射流式液动锤与原冲锤结构相比性能具有优势,冲击末速度得到了提高,冲击功与能量利用率平均增长7.9%与12.7%,新型冲锤结构减小了流体阻力消耗的能量,更有利于高能输出。另外,通过Ls-dyna非线性动力学分析,对2种冲锤结构的碎岩效果进行了研究,并对新型冲锤应力强度进行了分析。结果表明：新型冲锤结构的能量传递效率更高,且满足疲劳强度校核,相同冲击末速度下,岩层吸能值高于原冲锤结构;新型冲锤结构的吸能率较高,2种冲锤模型的吸能率随入射能量成非线性增长。     

Bioavailability of heavy metals in urban particles

Urban particles, as one of the toxic air pollutants, are important issues concerning air quality and public health, especially in large cities like Guangzhou （China）. Toxicological studies implicated heavy metals （particularly water-soluble metals） as a health hazard of particles. Once absorbed into human lung tissues, heavy metals are likely released from the particles and do harm to human body even in low concentrations. Thus, evaluating the bioavailability of heavy metals in urban particles is quite necessary. The particle samples used in this study were collected from a building roof in Guangzhou. Three different methods, sequential extraction procedure and two leaching tests, were employed to investigate the bioavailability of heavy metals in the particles. The sequential extraction scheme is specific for analyzing the chemical speciation of metals in particles, which consists of four fractions： F1： soluble and exchangeable metals; F2： carbonates, oxides and reducible metals; F3： bound to organic matter, oxidisable and sulphidic metals; and F4： residual metals. Leaching tests, GB 5086.2-1997 and TCLP, are standard methods developed by China-EPA and US-EPA and widely used in evaluating the toxicity of solid wastes. They were applied to gain additional information about more easily mobilized form of metal. Heavy metals in extraction solution, including Cu, Zn, Pb, Cd, Cr, and Ni, were analyzed by ICP-MS. According to the data from the total concentration analysis, the relative contents of 6 heavy metals in particles follow the order of Pb〉Zn〉Cu〉Cr〉Ni〉Cd. The results of sequential extraction showed that more than 50% of Cu, Zn and Cd were distributed in the F1, F2, and F3. This indicated that the bioavailability of Cu, Zn and Cd in the particles is much higher than that of Pb, Cr, and Ni. Leaching tests revealed that the concentrations of heavy metals in leachate are relatively lower than the regulatory level. The results of TCLP are much higher than those of GB 5086.2-1997, mainly due to the low pH value of the extraction fluid.     

Chemical speciation of heavy metals and arsenic in tailings and soils contaminated by mining activities （Northern Portugal）

A chemical sequential speciation of heavy metals （Fe, Mn, Cu, Zn, Pb, Cd, Sn, W, Bi, Ni, Cr, Mo, Co） Al, Ti and As in tailings and soils around five W/Sn mines （Adoria Mine, Ervedosa Mine, Regoufe Mine, Rio de Frades Mine and Tarouca Mine-Northern Portugal） was realized using a 7-steps fractionation procedure. Each of the chemical fractions was operationally defined as （Dold and Fontbote 2001）： （1） water-soluble; （2） exchangeable; （3） bound to Fe oxyhydroxides （or easily reducible）; （4） bound to Fe oxides （or moderately reducible）; （5） bound to organic matter and secondary Cu-sulfides; （6） bound to primary sulfides; and （7） residual. The extracted element contents at each step were measured by ICP-MS. Samples were also analyzed for pH, electrical conductivity and organic matter. The results allowed us to notice that： （1） the pH was the main factor controlling the geochemical distribution of the studied elements. The tailing and soil samples were very acid, with an average pH of approximately 4.37. Some metal cations （Mn, Cd, Cu, Zn, Pb, Co, Cr, Ni） behave in a similar way, revealing important enrichments in the most bioavailable fractions （water-soluble and exchangeable fractions）. In contrast, oxyanions such as Mo and As show low mobility through adsorption to Fe（Ⅲ） oxyhydroxides dissolved in the two reducible fractions. These results reflect the pH dependent adsorption on the clay minerals, Fe and Mn oxyhydroxides and the co-precipitation with these secondary minerals; （2） residual fraction was the most important fraction for Sn, Ti, Al, Mn, V, Cr and Zn. These results suggest that in these soils these elements are in a detrital, non-available form; （3） large amounts of Fe, Mn, Cu, Zn, Pb, Cd, Bi, Cr, Ni, Co and As were present in the most bioavailable fractions in all sampling sites as consequence of the oxidation and acidification processes in sulfidic mine wastes;     

桦南县土地集约利用出现的问题及对策

一、桦南县土地集约利用现状 1．桦南县土地利用现状 桦南县土地总面积4415．60kin：,其中县辖土地开发总面积2978．94kin：,土地利用率达到89．73％,其中农业用地面积2756．47km^2,占县属土地总面积的84．56％,垦殖率49．08％。