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301.
为探讨生物炭对农田化肥面源污染的防控效果,本文以北运河流域(北京段)下游"上壤下砂"、施肥量大、易漏水漏肥菜田为研究对象,分析了田间条件下不同用量生物炭配合化肥底施和施炭基肥对土壤氮磷纵向迁移、结球生菜产量品质及土壤微生物数量的影响.结果表明:与单施化肥(T1)相比,①化肥配施生物炭750 kg·hm-2(T2)、22...  相似文献   
302.
Recreational fisheries are increasingly important in fisheries management; for some species, recreational take rivals or exceeds the amount harvested by commercial fishermen. Most recreational fisheries are regulated with gear restrictions, bag limits, and time/area closures, but there is increasing interest in the market-based solutions employed in commercial fisheries — this despite the lack of an adequate bioeconomic theory of the joint commercial/recreational aspects of many recreational fisheries. This paper integrates a detailed production specification with traditional bioeconomic tools in order to better understand the implications of rationalization schemes targeted at the charter sector. While confirming some of the qualitative conclusions of the commercial fisheries literature on open access and regulated open access our model also generates rich and novel predictions with respect to input choices, the number of vessels and congestion externalities. We devise a system of instruments that generate efficient outcomes and extensively discuss issues associated with their real-world implementation.  相似文献   
303.
The parameters that are most commonly used in risk assessment, LCx values or no observed effect concentrations, both have serious drawbacks. As an alternative, No effect concentrations (NEC) as a parameter in a process-based model, offer great potential in risk assessment.  相似文献   
304.
In several vertebrate taxa, males and females differ in the proportions of time they individually devote to vigilance, commonly attributed to sex differences in intra-specific competition or in absolute energy requirements. However, an effect of sex on collective vigilance is less often studied (and therefore rarely predicted), despite being relevant to any consideration of the adaptiveness of mixed- vs single-sex grouping. Controlling for group size, we studied the effect of sex on vigilance in the sexually dimorphic eastern grey kangaroo Macropus giganteus, analysing vigilance at two structural levels: individual vigilance and the group’s collective vigilance. Knowing that group members in this species tend to synchronise their bouts of vigilance, we tested (for the first time) whether sex affects the degree of synchrony between group members. We found that females were individually more vigilant than males and that their vigilance rate was unaffected by the presence of males. Collective vigilance did not differ between female-only and mixed-sex groups of the same size. Vigilance in mixed-sex groups was neither more nor less synchronous than in single-sex groups of females, and the presence of males seemed not to affect the degree of synchrony between females. Sixty-six percent of vigilant acts were unique (performed when no other kangaroo was alert), and only about one unique vigilant act in every three induced a collective wave of vigilance. The proportions of vigilant acts that were unique were 60% for females but only 46% for males. However, the sexes differed little in the rates at which their unique vigilant acts were copied. This limited study shows that the differences in vigilance between male and female kangaroos had no discernible effect upon collective vigilance.  相似文献   
305.
介绍了钙基脱硫剂固硫后形成的CaOCaSO4固体混合物中钙和硫酸根的测定方法,改进了文献中微量硫酸根的一分析,分析了滴定过程听机理。先用高氯酸将固体混合物溶解形成水溶液,然后以杜试剂为批示剂,用高氯酸钡溶液滴定溶液中的微量硫酸根,并用EDTA法以钙红为指示剂滴定溶液中的钙离子,从而可以计算出钙基脱硫剂的固硫率(表示为脱硫后固体混合物中的钙硫化)。  相似文献   
306.
The proactive displacement by public authorities of populations from areas perceived to be exposed to a high risk of disaster presents complex human rights challenges. Provided that no ulterior motive is at play, the use of compulsory evacuations and relocations as policy responses to such risk is mandated by the duty to protect the right to life. However, proactive displacement in the interest of saving lives can be problematic as such measures can lead to the limitation of other human rights, resulting in an intricate assessment of whether compulsory evacuation or permanent relocation is proportional in any given circumstance. Such an analysis demands critical attention by public authorities to the perception of the disaster risk in question and problematises claims to objectivity of official risk assessments. Furthermore, it poses the question as to whether measures designed to address the disaster risk in question that are less intrusive than relocation may be available to public authorities.  相似文献   
307.
为探究不同省级区域雾霾、经济增长和环境规制之间的空间关联效应,本文提出针对雾霾的引力模型空间权重矩阵,并利用该矩阵建立了空间杜宾模型,分别对全国、西部、中部和东部省区的面板数据进行了空间计量检验。实证结果显示:全国雾霾的莫兰指数值显著,且取值介于0.367—0.460之间;雾霾"重心"呈现先向东南再向西北移动的趋势,移动距离为76 557 m;雾霾的莫兰指数值为东部省区最大,西部省区最小,中部省区介于二者之间。全国的雾霾与经济增长之间呈显著的"U"型曲线,而西部、中部和东部省区则呈倒"U"型曲线,其中中部省区的曲线最为陡峭,西部省区次之,东部省区最为平缓。环境规制每增加1%,只有西部和东部的雾霾相应减少,且各自相应下降0.009和0.010个百分点。西部和东部经济增长的溢出效应均显著,而环境规制的溢出效应不显著。研究结果表明:(1)雾霾在空间上表现出集聚的特点,全国和三个区域的雾霾都存在显著的正向空间溢出效应,这种空间依赖性在时间维度上大致呈加强的趋势;雾霾的空间相关性表现为东部省区最强,西部省区紧随其后,中部省区最低。(2)西部和东部省区部分省市还未过拐点,全国意义上的环境库茨涅兹假说是不存在的,或者是至少还未出现。(3)西部和东部环境规制效果较为理想,而中部省区的环境规制效果不佳;从全国总体来看,当前的环境规制整体上对雾霾并未起到有效的抑制作用。(4)东西部省区和中部省区经济增长对雾霾溢出效应分别表现为正向和反向;环境规制对雾霾的溢出效应并不显著。建议加强对雾霾的区域协同治理,重点推进西部和东部省区经济结构的转型升级,调整和完善西部、中部和东部省区的环境规制政策。  相似文献   
308.
Flood forecasts and warnings are intended to reduce flood‐related property damages and loss of human life. Considerable research has improved flood forecasting accuracy (e.g., more accurate prediction of the occurrence of flood events) and lead time. However, the delivery of improved forecast information alone is not necessarily sufficient to reduce flood damage and loss of life, as people have varying responses and reactions to flood warnings. This study develops an agent‐based modeling framework that evaluates the impacts of heterogeneity in human behaviors (i.e., variation in behaviors in response to flood warnings), as well as residential density, on the benefits of flood warnings. The framework is coupled with a traffic model to simulate evacuation processes within a road network under various flood warning scenarios. The results show the marginal benefit associated with providing better flood warnings is significantly constrained if people behave in a more risk‐tolerant manner, especially in high‐density residential areas. The results also show significant impacts of human behavioral heterogeneity on the benefits of flood warnings, and thus stress the importance of considering human behavioral heterogeneity in simulating flood warning‐response systems. Further study is suggested to more accurately model human responses and behavioral heterogeneity, as well as to include more attributes of residential areas to estimate and improve the benefits of flood warnings.  相似文献   
309.
在钙基吸收剂捕集CO2的过程中,吸收剂转化率会随着循环次数的增加而迅速降低。钙基吸收剂的水合改性作为改善吸收剂循环转化率的主要方法之一受到了国内外学者的广泛关注。总结了目前国内外研究者对不同的吸收剂、循环捕集条件下的水合改性方法的研究成果。结果表明,在循环过程中的不同阶段对吸收剂进行水合处理后得到的效果不同。其中,在碳酸化阶段、煅烧阶段、循环捕集前预处理以及煅烧后对吸收剂水合改性.吸收剂捕集CO2的能力均得到了改善;碳酸化反应后对吸收剂进行水合处理是否对循环吸收有利还存在争议。目前,利用水合改性的方法提高钙基吸收剂循环捕集CO2能力的机理还存在争议,且水合改性后的吸收剂机械性能差以及此方法能耗高的问题尚待解决。  相似文献   
310.
物联网的发展如火如荼,作为新兴高技术产业的重要组成部分,物联网技术广泛应用于各行各业。文中阐述了环保物联网技术及其应用系统,详细介绍了以在线监测、视频和工况监测三种手段联合监控的感知端技术,信息传输网络技术,以及环保物联网智慧监控平台,描述了物联网技术在污染企业综合监控管理、环境质量综合监测管理、环境应急管理中的实际应用,最后提出环保物联网应在技术规范、技术保障、感知设备研发、感知数据处理等方面进行深入研究,形成一个全覆盖、全运转、全应用、可持续的环保物联网体系。  相似文献   
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