青海省限制开发区人口容量研究

对主体功能区划分后,必然会由此突现一些问题,其中合理的人口容量就是亟待解决的关键问题之一。青海省地处青藏高原东北部,是连接青藏高原,西北地区及华中地区的重要区域,其区域内有三江源等重要的生态功能区,该区域的生态建设和经济发展具有很重要的意义。尤其是在青海省内限制开发区面积较大,其发展更有着举足轻重的作用。本文以青海省主体功能区的划分为基础,借鉴相关的研究成果,利用适度人口容量的PRE预测方法,预测并讨论青海省限制开发区的适度人口容量,分析了适度人口容量和该地区可持续发展的关系,提出了人口迁移的意见,将对青海省主体功能区的形成和发展有一定的借鉴和帮助。     

In situ phytoremediation of arsenic- and metal-polluted pyrite waste with field crops: effects of soil management

Sunflower, alfalfa, fodder radish and Italian ryegrass were cultivated in severely As-Cd-Co-Cu-Pb-Zn-contaminated pyrite waste discharged in the past and capped with 0.15 m of unpolluted soil at Torviscosa (Italy). Plant growth and trace element uptake were compared under ploughing and subsoiling tillages (0.3 m depth), the former yielding higher contamination (∼30%) in top soil.Tillage choice was not critical for phytoextraction, but subsoiling enhanced above-ground productivity, whereas ploughing increased trace element concentrations in plants. Fodder radish and sunflower had the greatest aerial biomass, and fodder radish the best trace element uptake, perhaps due to its lower root sensitivity to pollution. Above-ground removals were generally poor (maximum of 33 mg m⁻² of various trace elements), with Zn (62%) and Cu (18%) as main harvested contaminants. The most significant finding was of fine roots proliferation in shallow layers that represented a huge sink for trace element phytostabilisation.It is concluded that phytoextraction is generally far from being an efficient management option in pyrite waste. Sustainable remediation requires significant improvements of the vegetation cover to stabilise the site mechanically and chemically, and provide precise quantification of root turnover.     

Sexual difference in mercury concentrations of lake trout (Salvelinus namaycush) from Lake Ontario

We determined total mercury (Hg) concentrations in 50 female lake trout (Salvelinus namaycush) and 69 male lake trout from Lake Ontario (Ontario, Canada and New York, United States). Results showed that, on average, males were 8% higher in Hg concentration than females in Lake Ontario. We also used bioenergetics modeling to determine whether a sexual difference in gross growth efficiency (GGE) could explain the observed sexual difference in Hg concentrations. According to the bioenergetics modeling results, male GGE was about 3% higher than female GGE, on average. Although the bioenergetics modeling could not explain the higher Hg concentrations exhibited by the males, a sexual difference in GGE remained a plausible explanation for the sexual difference in Hg concentrations of the lake trout. In an earlier study, male lake trout from Lake Ontario were found to be 22% higher in polychlorinated biphenyl (PCB) concentration than females from Lake Ontario. Thus, although males were higher in both Hg and PCB concentrations, the degree of the sexual difference in concentration varied between the two contaminants. Further research on sexual differences in Hg excretion rates and Hg direct uptake rates may be needed to resolve the disparity in results between the two contaminants.     

Nitrogen mediates above-ground effects of ozone but not below-ground effects in a rhizomatous sedge

Ozone and atmospheric nitrogen are co-occurring pollutants with adverse effects on natural grassland vegetation. Plants of the rhizomatous sedge Carex arenaria were exposed to four ozone regimes representing increasing background concentrations (background-peak): 10-30, 35-55, 60-80 and 85-105 ppb ozone at two nitrogen levels: 12 and 100 kg N ha⁻¹ yr⁻¹. Ozone increased the number and proportion of senesced leaves, but not overall leaf number. There was a clear nitrogen × ozone interaction with high nitrogen reducing proportional senescence in each treatment and increasing the ozone dose (AOT40) at which enhanced senescence occurred. Ozone reduced total biomass due to significant effects on root biomass. There were no interactive effects on shoot:root ratio. Rhizome tissue N content was increased by both nitrogen and ozone. Results suggest that nitrogen mediates above-ground impacts of ozone but not impacts on below-ground resource translocation. This may lead to complex interactive effects between the two pollutants on natural vegetation.     

Dissipation of polycyclic aromatic hydrocarbons (PAHs) in the rhizosphere: Synthesis through meta-analysis

Polycyclic aromatic hydrocarbons (PAHs) are widespread and persistent organic pollutants with high carcinogenic effect and toxicity; their behavior and fate in the soil-plant system have been widely investigated. In the present paper, meta-analysis was used to explore the interaction between plant growth and dissipation of PAHs in soil based on the large body of published literature. Plants have a promoting effect on PAH dissipation in soils. There was no difference in PAH dissipation between soils contaminated with single and mixed PAHs. However, plants had a more obvious effect on PAH dissipation in freshly-spiked soils than in long-term field-polluted soils. Additionally, a positive effect of the number of microbial populations capable of degrading PAHs was observed in the rhizosphere compared with the bulk soil. Our meta-analysis established the importance of the rhizosphere effect on PAH dissipation in variety of the soil-plant systems.     

The Introduction of the Precautionary Principle in Danish Environmental Policy: The Case of Plant Growth Retardants

In this paper, we investigate the Precautionary Principle (PP) in action. Precaution is a fairly new concept in environmental policy. It emerged back in the 1960s but did not consolidate until the 1980s, as it formed part of the major changes taking place in environmental policies at that time. The PP is examined in three contexts. Firstly, we look at the meaning of the concept and how it is disseminated through the media and public discourses to the political arenas of Denmark. Then we examine how the idea is adopted to the political level. Thirdly, we look briefly at the first Danish translation of the principle into a practical context, which includes translations into concrete scientific practices. It is concluded that if the PP shall be more than a simple “idea” or a frequently used “term,” emphasis must be put on the transformation of the concept into concrete practices, like e.g., the alternative testing regimes that we show in the case of plant growth-retarding pesticides presented in this paper.     

非稳态微生物污染物在建筑群内迁移的数值模拟

随着城市化进程的加快和城市中心人口密度的激增,微生物污染问题成为人们关注的热点.本文利用病毒群体动力学演化模型研究非稳态微生物污染的产生过程,并将模型结果作为非稳态污染源的源强引入污染物对流扩散方程.假设没有继发性感染,研究致病性微生物污染源对建筑群环境的影响,得到了建筑群表面及周围污染物浓度随时间的变化规律.假定致病感染浓度,得到了微生物污染源的影响范围,这为控制污染物扩散和建立致病微生物污染预警系统提供了理论指导.     

钝顶螺旋藻在有机污水处理方面的应用初探

以钝顶螺旋藻(Spirulina Platenis)A9、A9L(藻体长直型)2种藻株为实验材料,研究了不同浓度苯酚(Phenol)对2种藻株生长的影响。结果显示:①低浓度苯酚能促进实验藻株生长;②不同藻株对苯酚浓度敏感性和忍受力有差异;③钝顶螺旋藻A9、A9L藻株可用于含低浓度苯酚的有机污水处理。     

长江三角洲人口集聚与布局探讨

长江三角洲是我国重要的经济区域,是参与国际竞争、提高国际分工地位的代表地区,也是最主要的人口聚集区。随着国家贯彻落实科学发展观,推进人口分布、产业布局和经济环境在空间上的均衡发展,长三角在产业和人口方面的集聚效应将更加明显。从生态景观和经济发展的分析入手,开展了人口承载力和人口集聚的研究,大胆提出未来长三角人口集聚的规模以及在空间上的分布,同时提出建设六大都市圈和六大国际门户,形成网络化的城市空间布局,有效承接大量流入的人口和支撑产业的发展。     

基于中日比较的人口城市化对耕地影响机制研究

人口城市化是对耕地变动产生复合影响的一个过程.人口由农村向城市的转移是城市土地扩张的基本动力;这对耕地形成了占用的直接影响,我国人口城市比对耕地减少的直接影响度约在5%～10%之间.人口城市化对耕地的间接影响通过城市人均用地比农村少,土地利用集约度高,可以间接减少耕地占用;同时农村人口的减少,可以推动村镇合并,整理土地,增加耕地等途径来实现.因此,人口城市化对耕地存在积极的间接影响.人口城市化过程对耕地变动的复合影响结果是积极的还是消极的,将取决于一是城市化发展状态,即与工业化发展是否同步;二是村镇合并集中是否及时到位.为此,文章对中日人口城市化对耕地影响机制进行了比较.