首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   13篇
  免费   2篇
安全科学   1篇
环保管理   2篇
综合类   2篇
基础理论   2篇
污染及防治   5篇
评价与监测   2篇
社会与环境   1篇
  2020年   3篇
  2018年   1篇
  2017年   1篇
  2013年   1篇
  2012年   1篇
  2011年   1篇
  2008年   1篇
  2007年   2篇
  2005年   1篇
  2003年   1篇
  2002年   1篇
  2001年   1篇
排序方式: 共有15条查询结果,搜索用时 377 毫秒
1.
This paper presents initial investigations of a new approach to monitor ecosystem processes in complex terrain on large scales. Metabolic processes in mountainous ecosystems are poorly represented in current ecosystem monitoring campaigns because the methods used for monitoring metabolism at the ecosystem scale (e.g., eddy covariance) require flat study sites. Our goal was to investigate the potential for using nocturnal down-valley winds (cold air drainage) for monitoring ecosystem processes in mountainous terrain from two perspectives: measurements of the isotopic composition of ecosystem-respired CO2 (delta13C(ER)) and estimates of fluxes of CO2 transported in the drainage flow. To test if this approach is plausible, we monitored the wind patterns, CO2 concentrations, and the carbon isotopic composition of the air as it exited the base of a young (approximately 40 yr-old) and an old (>450 yr-old) steeply sided Douglas-fir watershed. Nocturnal cold air drainage within these watersheds was strong, deep, and occurred on more than 80% of summer nights. The depth of cold air drainage rapidly increased to tower height or greater when the net radiation at the top of the tower approached zero. The carbon isotope composition of CO2 in the drainage system holds promise as an indicator of variation in basin-scale physiological processes. Although there was little vertical variation in CO2 concentration at any point in time, we found that the range of CO2 concentration over a single evening was sufficient to estimate delta 13C(ER) from Keeling plot analyses. The seasonal variation in delta 13C(ER) followed expected trends: during the summer dry season delta 13C(ER) became less negative (more enriched in 13C), but once rain returned in the fall, delta 13C(ER) decreased. However, we found no correlation between recent weather (e.g., vapor pressure deficit) and delta 13C(ER) either concurrently or with up to a one-week lag. Preliminary estimates suggest that the nocturnal CO2 flux advecting past the 28-m tower is a rather small fraction (<20%) of the watershed-scale respiration. This study demonstrates that monitoring the isotopic composition and CO2 concentration of cold air drainage at the base of a watershed provides a new tool for quantifying ecosystem metabolism in mountainous ecosystems on the basin scale.  相似文献   
2.
The dioxin removing capacity of the shell dedioxin system (SDDS-a Ti/V oxidative type catalyst) has been tested using the Ume? lab-scale incinerator over the temperature range 100-230 degrees C and at space velocities of 8000 and 40,000 h(-1). Other analogous organic compounds, such as PCBs, PAHs, chlorobenzenes and chlorophenols have also been investigated. Results show a high degree of dioxin removal already at 100 degrees C (82%), which occurs mainly by adsorption. When the temperature is raised a transition towards destruction is seen and at 150 degrees C, gas hour space velocity (GHSV) 8000 and at 230 degrees C, GHSV 40,000 virtually all removal is by destruction. High PCDD/F destruction efficiencies are reported (> 99.9%, based on I-TEQ); the other dioxin-related species and PAHs are also removed and destroyed to a significant extent. The SDDS has proved to be an effective means of destroying organic compounds in the gas phase, particularly dioxins, at temperatures as low as 150 degrees C.  相似文献   
3.
Agrochemical spray drift; assessment and mitigation--a review   总被引:1,自引:0,他引:1  
During application of agrochemicals spray droplets can drift beyond the intended target to non-target receptors, including water, plants and animals. Factors affecting this spray drift include mode of application, droplet size, which can be modified by the nozzle types, formulation adjuvants, wind direction, wind speed, air stability, relative humidity, temperature and height of released spray relative to the crop canopy. The rate of fall of spray droplets depends upon the size of the droplets but is modified by entrainment in a mobile air mass and is also influenced by the rate of evaporation of the liquid constituting the aerosol. The longer the aerosol remains in the air before falling to the ground (or alternatively striking an object above ground) the greater the opportunity for it to be carried away from its intended target. In general, all size classes of droplets are capable of movement off target, but the smallest are likely to move the farthest before depositing on the ground or a non-target receptor. It is not possible to avoid spray drift completely but it can be minimized by using best-management practices. These include using appropriate nozzle types, shields, spray pressure, volumes per area sprayed, tractor speed and only spraying when climatic conditions are suitable. Field layout can also influence spray drift, whilst crop-free and spray-free buffer zones and windbreak crops can also have a mitigating effect. Various models are available to estimate the environmental exposure from spray drift at the time of application.  相似文献   
4.
Jones  Benjamin L.  Unsworth  Richard K. F. 《Ambio》2020,49(7):1257-1267

Malaria is a serious global health issue, with around 200 million cases per year. As such, great effort has been put into the mass distribution of bed nets as a means of prophylaxis within Africa. Distributed mosquito nets are intended to be used for malaria protection, yet increasing evidence suggests that fishing is a primary use for these nets, providing fresh concerns for already stressed coastal ecosystems. While research documents the scale of mosquito net fisheries globally, no quantitative analysis of their landings exists. The effects of these fisheries on the wider ecosystem assemblages have not previously been examined. In this study, we present the first detailed analysis of the sustainability of these fisheries by examining the diversity, age class, trophic structure and magnitude of biomass removal. Dragnet landings, one of two gear types in which mosquito nets can be utilised, were recorded across ten sites in northern Mozambique where the use of Mosquito nets for fishing is common. Our results indicate a substantial removal of juveniles from coastal seagrass meadows, many of which are commercially important in the region or play important ecological roles. We conclude that the use of mosquito nets for fishing may contribute to food insecurity, greater poverty and the loss of ecosystem functioning.

  相似文献   
5.
Invertebrate gleaning (walking) fisheries are common within intertidal seagrass meadows globally, contributing to the food supply of hundreds of millions of people, but understanding of these fisheries and their ecological drivers are extremely limited. The present study provides a unique analysis of these fisheries using a combined social and ecological approach. Catches contained 34 species and were dominated by Bivalves, Urchins and Gastropods. CPUE in all sites varied from 0.05 to 3 kg gleaner−1 hr−1, respectively, with the majority of fishers being women and children. Landings were of major significance for local food supply and livelihoods at all sites. Local ecological knowledge suggests seagrass meadows are declining in line with other regional trends. Increasing seagrass density significantly and positively correlated with CPUE of the invertebrate gleaning (r = 0.830) highlighting the importance of conserving these threatened habitats. Understanding the complexities of these fisheries, their supporting habitats and their sustainability is important for the support of sustainable coastal livelihoods.  相似文献   
6.
Building on role congruity theory, we predict that innovative work behaviors are stereotypically ascribed to men more than to women. Because of this bias, women who innovate may not receive better performance evaluations than those who do not innovate, whereas engaging in innovative work behaviors is beneficial for men. These predictions were supported across 3 complementary field and experimental studies. The results of an experiment (Study 1; N = 407) revealed that innovative work behaviors are stereotypically associated with men more than women. In Studies 2 and 3, using multisource employee evaluation data (N = 153) and by experimentally manipulating innovative work behaviors (N = 232), respectively, we found that favorable performance evaluations were associated with innovative work behaviors for men but not for women. These studies highlight a previously unidentified form of sex bias and are particularly important for those wishing to increase innovative behaviors in the workplace: We need to address this phenomenon of “think innovation‐think male.”  相似文献   
7.
Environmental Science and Pollution Research - Limited information is available on the risk to aquatic environments from the aerial application of copper fungicides to treat dothistroma needle...  相似文献   
8.
为评价三唑酮在大白菜施用后的环境安全性,建立了GC测定蔬菜及土壤中三唑酮残留的方法,进行露地与设施栽培条件三唑酮在大白莱和土壤中的消解动态和最终残留研究.在大白菜和土壤中的最低检测质量分数均为0.001 mg/kg,三唑酮的平均加标回收率为81.5%~110.6%,变异系数为1.32%~6.04%.消解动态试验为2倍推荐使用剂量施药1次,三唑酮在设施栽培大白菜的半衰期分别为2.72~3.30 d和3.21~3.35 d;露地栽培为2.35~2.87 d和2.30~3.12 d.设施栽培大白菜中三唑酮残留量与用药量正相关,随着施药量的增加,消解速度减慢,残留量相应增大.研究可为制定三唑酮设施栽培大白菜上最大残留限量和合理使用准则以及风险评估提供科学依据.  相似文献   
9.
This paper used the case study of the Wakatobi Marine National Park, Indonesia to examine changes in the diversity, density and maturity of grouper species over a 5-year period following the establishment of a small-scale no-take area (NTA). This work was carried out to investigate whether “small” NTAs could be effective management strategies over a time scale that is relevant to local fishery communities and their perception of management success. Our research also documents the ecology of these species, information essential if we are to understand how management practises are to affect coral reef fish species. Designation of this “small NTA” increased the density of groupers by 30% over a 5-year period of protected status. After 5 years of protection, grouper populations within this NTA were more mature and double the density of those within the adjacent lightly fished sites and nearly five times those of a heavily fished site. During this time all other nearby fished sites underwent large declines in grouper density. The nearby lightly fished Kaledupa site decreased by up to 50% year−1. Such drastic declines are considered the impact of the exponential development of ever efficient and unsustainable methods of fishing within the study region. This NTA was not of benefit to all grouper species; the reasons for which are not clear. Such questions require further detailed research about the life history, population and behavioural ecology of Indo-Pacific grouper species. Such information is critical for urgently needed fisheries management. The present study found that a small scale NTA of 500 m length was large enough to increase the population of top predatory fish. In conjunction with other socially acceptable small scale NTAs it could help maintain and increase important fish stocks over a larger area. The use of “small” NTAs within networks of reserves should become a useful tool in the management of the locally exploited coral reefs.  相似文献   
10.
Deploying heating technologies, such as air-source heat pumps (ASHPs), can respond to the dual challenges of tackling fuel poverty and reducing carbon emissions from domestic energy consumption. In the UK, ASHP performance has been found to be below design levels. Elements of three strands of literature – innovation diffusion, environmental psychology and neighbourhood effects – are combined to gain insights into why the adoption and performance of ASHPs are lagging policy targets and design potential. Evidence from users, installers and area-based scheme facilitators suggests that the perceived complexity of the technology is a barrier. The level of technology maturity and the typical profile of the elderly fuel poor do not match; the target group might prefer to be late adopters or laggards in adopting technology. The role of installers is critical as the disruption from installation is a barrier to adoption and ASHPs place demands on users to change existing practices.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号