重金属在河口区潮汐界面与盐度界面响应规律研究

河口潮汐、盐度、悬浮颗粒物特征因影响化学物质在水体与其他介质之间分配行为,使得咸淡水生物利用度上产生差别,造成咸淡水水质基准标准的差异.重金属如铜,锌,铅,镉和铬等指标由于广泛分布在淡水及海水中,在较高的浓度下可具毒性效应,是现行《地表水环境质量标准》(GB 3838-2002)和《海水水质标准》(GB 3097-1997)常规监测项目.本研究以大辽河口为例,探索这些重金属指标在咸淡水河口区衔接情况和响应规律.首先,基于生物、化学和地质地理相似性确定潮汐界面(TCI)和河海边界(FSI)的位置,划分为潮汐淡水区及混合区.其次,分析了一个潮汐周期内重金属指标的变化特征,以及潮汐淡水区及混合区内盐度和悬浮颗粒物对分配系数Kd的影响,结果表明砷、镉和铬等指标更易受盐度的影响,而锌、铜、铅和镍等指标更易受悬浮颗粒物和潮汐状态的影响.最后,结合潮汐状态和分配系数研究结果,根据这些指标在TCI和FSI的变化趋势,归纳为两类响应规律:第一类如砷、镉和铬等指标,这类指标在FSI具有明显的突变点;第二类如锌、铜、铅和镍等指标,从TCI开始发生变化.两类指标在水相-沉积相-颗粒相介质的分配行为表明颗粒相和沉积相具有相似的变化趋势,尤其颗粒相中的重金属浓度,取决于悬浮颗粒物的浓度,指标响应差异主要存在于水相中.通过本研究识别出易受不同环境因子(如盐度和SS)控制的敏感指标,提出需关注河口本身特征造成的指标背景差异的必要性,将有助于我国现行水质标准制定、修订工作的实施和开展.     

锈蚀钢筋混凝土圆柱抗震性能的试验研究

对不同锈蚀程度的钢筋混凝土圆柱进行低周反复试验,研究了不同轴压比下的钢筋锈蚀率对钢筋混凝土圆柱滞回曲线、骨架曲线、刚度、延性及耗能能力的影响;给出了试件累积耗能、屈服荷栽、极限荷栽、荷栽最大值和位移延性系数与钢筋锈蚀率和轴压比的关系.研究表明,随着钢筋锈蚀率和轴压比的增大,试件的滞回曲线趋于干瘪,骨架曲线下降段变陡,试...     

基于静态特征和动态行为的火灾检测模型

为实时准确地检测视频监控的火灾信号,减少火灾误报,提出1种基于静态特征和动态行为的火灾检测方法.利用改进的Faster RCNN检测模型,根据可疑火灾区域的颜色特征和空间特征对其进行目标检测和特征降维,与传统的Faster RCNN相比平均检测精度提升5％;利用ILSTM对连续帧中的特征进行累加,对短期内是否发生过火灾...     

事故车辆影响下的城市三车道道路交通流仿真

为探究事故车辆对城市三车道道路交通影响机制,首先,分析考虑事故车辆的城市三车道道路交通流特征;然后,构建左车道优先且考虑主动抢道和被动抢道行为的元胞自动机交通流模型;最后;研究事故持续时间td变化时事故车辆分别位于M道和R道的城市道路交通流演化.结果 表明:事故车辆会形成交通瓶颈,呈现上游车辆聚集下游车辆稀疏的时空特征...     

Sexual selection on mature male parr of masu salmon (Oncorhynchus masou): does sneaking behavior favor small body size and less-developed sexual characters?

In many salmonid species, males exhibit morphological dimorphism associated with alternative mating behaviors. ”Precocious males” have a small body size with little or no development of sexual characters and adopt sneaking to gain access to females, while ”migratory males” of large body size and well-developed secondary sexual characters fight. We quantified selection on precocious male parr of masu salmon (Oncorhynchus masou) under simulated natural conditions to examine the contribution of morphology to sneaking success. In contrast to the prediction that sneaking behavior favors small body size, we detected selection favoring relatively large body size for sneaking success. This selection pressure was caused by the dominance hierarchy within parr and may have been facilitated by indifference of dominant migratory males to parr. Unlike the secondary sexual characters exhibited by migratory male salmon, such as the hooked snout and humped back, no morphological characters other than body size contributed to the reproductive success of masu salmon parr. This non-contribution may have been responsible for the lack of development of sexual characters in precocious males. Received: 15 November 1999 / Accepted: 20 May 2000     

Trust,political orientation,and environmental behavior

A growing body of large-N cross-national studies has identified key predictors of environmental behavior. Adopting a social dilemma perspective, where individuals must choose collective over self-interest to act pro-environmentally, integrated national datasets for 30 countries are used to examine the effects of generalized trust, trust in government, leftism, and post-materialism on three types of environmental behavior (intended action, informal action, and formal action). At the individual level, all predictors but institutional trust have significant positive effects on each type of behavior. Institutional trust is associated with greater willingness to make economic sacrifice for the environment and with less frequent informal environmental behavior, but it is unrelated to formal behavior. However, at the country level, the effect of trust is limited to intended behavior and depends on the type of trust. Individuals in countries with higher generalized trust averages are less willing to sacrifice for the environment, and those in countries with higher averages of institutional trust are more willing to do so.     

The farmer as a landscape steward: Comparing local understandings of landscape stewardship,landscape values,and land management actions

We develop a landscape stewardship classification which distinguishes between farmers’ understanding of landscape stewardship, their landscape values, and land management actions. Forty semi-structured interviews were conducted with small-holder (<5 acres), medium-holders (5–100 acres), and large-holders (>100 acres) in South-West Devon, UK. Thematic analysis revealed four types of stewardship understandings: (1) an environmental frame which emphasized the farmers’ role in conserving or restoring wildlife; (2) a primary production frame which emphasized the farmers’ role in taking care of primary production assets; (3) a holistic frame focusing on farmers’ role as a conservationist, primary producer, and manager of a range of landscape values, and; (4) an instrumental frame focusing on the financial benefits associated with compliance with agri-environmental schemes. We compare the landscape values and land management actions that emerged across stewardship types, and discuss the global implications of the landscape stewardship classification for the engagement of farmers in landscape management.     

我国人口老龄化加速发展对城市化发展速度的影响

中国的城市化水平在过去的20余年里以年均超过一个百分点的速度提升,然而在城市化主要依靠人口乡城迁移推动的模式下,人口年龄结构老化对城市化发展的影响日渐显现。文章通过年龄移算法描述了乡城人口迁移流动的年龄模式,发现我国农村人口乡城迁移概率随年龄的分布呈现"中间大,两头小"的特征。然后,文章分析了此种年龄模式形成的原因,认为制度是影响乡城迁移年龄模式的决定性因素,制度变迁的缓慢性以及路径依赖决定了短期内我国人口乡城迁移年龄模式的稳定性。基于此,文章预测了人口老龄化对未来中国人口城市化发展的影响,得出的基本结论是,未来中国城市化发展的水平提高将进入一个相对平缓的时期,年度城市化水平的提升将显著低于过去一个时期,对未来10-20年中国城市化发展水平的预期未可过于乐观。针对这一结论,文章建议在未来的城市化过程中应完善社会融入机制和提升城市化质量。     

Satisfaction with fishing and the desire to leave

Predicting who may leave a fishery is an important consideration when designing capacity reduction programs to enhance both ecological and economic sustainability. In this paper, the relationship between satisfaction and the desire to exit a fishery is examined for the Queensland East Coast Trawl fishery. Income from fishing, and changes in income over the last 5 years, were key factors affecting overall satisfaction. Relative income per se was not a significant factor, counter to most satisfaction studies. Continuing a family tradition of fishing and, for one group, pride in being a fisher was found to be significant. Satisfaction with fishing overall and the challenge of fishing were found to be the primary drivers of the desire to stay or leave the fishery. Surprisingly, public perceptions of fishing, trust in management and perceptions of equity in resource allocation did not significantly affect overall satisfaction or the desire to exit the fishery.     

人的差错行为对矿山安全的模糊综合评判

人的差错行为对矿山安全有着极大的影响.对人的差错行为因素进行分析,利用模糊综合评判的方法,对某煤矿工人作业行为安全性的评判,确定该煤矿矿工行为的安全状态,从而及时了解矿工情绪、心理等状态,适时地进行安全培训教育,以保障人员安全作业.