共查询到20条相似文献，搜索用时 31 毫秒
1.
Beyond the circle of poison: Significant shifts in the global pesticide complex, 1976–2008 总被引：1，自引：0，他引：1
Almost 30 years after its introduction, the “circle of poison” remains a common conceptualization of the global pesticide complex among scholars and especially in popular understanding. The circle of poison describes a situation in which, pesticides banned in industrialized countries continue to be manufactured there and exported to developing countries, are then used in developing countries almost entirely on export crops, and return to industrialized countries as pesticide residues on food. Using secondary data and a case study of pesticide use in Costa Rica, I review the applicability of the circle of poison conceptualization to the current global pesticide complex. I argue that (1) the circle of poison is no longer accurate due to important global changes in pesticide regulation, production, trade, sales, and use driven by a number of dynamic economic, social, and ecological processes; (2) using industrialized countries’ pesticide regulations as proxies for safety should be replaced by multi-characteristic risk assessments; and (3) revisions of the circle of poison conceptualization should be updated because of export farmers’ adoption of newer classes of pesticides. The paper concludes by offering a new characterization of the global pesticide complex vis-à-vis pesticide use in developing countries: pesticide divergence by market orientation. 相似文献
2.
Residuals from agricultural pesticides threaten the environment and human health. Climate change alters these externalities because it affects pest pressure and pesticide application rates. This study examines damages from pesticide externalities in US agriculture under different climate projections and the effects of alternative regulations. We find divergent impacts of externality regulation and climate change on agricultural production in the US. A Pigovian tax on pesticide externalities generally increases crop production cost, but farm revenue improves because of increased commodity prices. Climate change generally decreases US farm revenue because production increases and prices fall. Results also show a heterogeneous effect of climate change on pest management intensities across major crops. 相似文献
3.
《大气与海洋》2013,51(4):294-307
Abstract Detailed patterns of spatial variability in surface temperature can be observed with the use of thermal infrared data from satellites. A method is developed to use clear‐sky thermal infrared satellite data to evaluate traditional monthly average maximum air temperature maps interpolated from observations at surface stations using a statistical thin plate smoothing spline method. Results of comparisons over Alberta, Manitoba and Saskatchewan from June to October, for the years 2001 to 2005, are presented. The satellite data allow identification of some limitations in the interpolation technique at high altitudes in mountain ranges and in data‐sparse areas due to low station density. In the data‐sparse areas, the highest discrepancies could be linked to the unrepresentativeness of the stations because of different land cover or the presence of water bodies. Conversely, the interpolated air temperature maps allow the identification of problems with using thermal infrared data to estimate near‐surface air temperatures in areas of significant moisture deficit and at the locations of water bodies. 相似文献
4.
Gour-Tsyh Yeh 《Boundary-Layer Meteorology》1974,7(1):21-37
The two-layer system of an atmosphere over water bodies is reduced to a single-layer problem. Values of the interfacial quantities, such as the friction velocity, the surface velocity, the angles, and , between the surface shear stress and the geostrophic wind velocity and the surface wind velocity, respectively, and the surface roughness, all of which depend upon external parameters, such as the geostrophic wind and stratifications, are obtained. The geostrophic drag coefficient C
d, the geostrophic wind coefficient C
f, and the angles , and , of the turbulent flow at the sea-air interface are functions of a dimensionless number, mfG/kg, with S
1 and S
2 as two free stratification parameters. The surface roughness is uniquely determined from the geostrophic wind rather than from the wind profile in the boundary layer.Formerly Visiting Research Associate, Applied Physics Branch, Earth Observations Division, NASA-Manned Spacecraft Center, Houston, Texas. 相似文献
5.
D. P. Samsonov A. I. Kochetkov E. M. Pasynkova M. A. Zapevalov 《Russian Meteorology and Hydrology》2017,42(5):345-352
Experimental results are presented of the estimation of pollution levels of Lake Baikal unique ecosystem (air, surface and deep water, soil, bottom sediments, and aquatic biota) with persistent organic pollutants (POPs) which were included to the list of Stockholm Convention (polychlorinated biphenyls, organochlorine pesticides, toxaphene, and polybrominated diphenyl ethers). The ranges of POPs concentration are determined and statistical characteristics (mean and median) over the period of observations are calculated. It is demonstrated that the wide variation range of POPs concentration depends on environmental factors and on the POPs source (local sources or global transport). 相似文献
6.
利用"中国西北干旱区陆—气相互作用实验"观测的资料,分析了大气湿度、土壤含水量、与土壤含水量相关的陆面参数及其他陆面参数特征。为了验证新的陆面参数及参数化公式,将新陆面参数与参数化公式输入陆面模式进行模拟,将模拟值与观测值进行了比较。结果表明输入新参数及参数化公式的模拟效果更好。 相似文献
7.
On the base of weather station data and the NCEP/NCAR reanalysis data, atmospheric water resource over the Qilian-Heihe Valley was analyzed, and the result shows that, the less water vapor transport source and the divergence of atmospheric stream eld are main cause for resulting in the little water vapor content over the Qilian-Heihe Valley. Annual mean atmospheric water vapor content over the Qilian-Heihe Valley is merely 30% and 40% over the south of the Yangtze River and the middle of North China, respectively.
Because of its high elevation and high precipitation e ciency, the Qilian Mountains area has plentiful precipitation. And the lower surface temperature and evaporation make the surface water material gather easily and thus form runo . As for the Heihe Valley, for the low precipitation efficiency, there is little precipitation and its value is corresponded to the surface evaporation. Thus its contribution to the surface water is very small. In the grid of 2.5°×2.5° over the Qilian-Heihe Valley, annual influent and effluent water vapor amount are 668×109 and 650×109 m3, respectively. The net influent water vapor amount is 18×109 m3. The influent water vapor takes on reducing tendency and with an obvious descent in period of the 1970s-1980s. In the recent 40 years, because the air temperature over the Qilian-Heihe Valley is rising and the atmospheric water vapor content is descending, the decrease of precipitation would be inevitable. 相似文献
8.
The methane concentration in the waste water coming to the aeration station is 1130 μl/l on average and it decreases to 11
μl/l after all purification stages. Experimentally measured methane fluxes to the atmosphere from the waste water under purification
and sewage sediments of silt fields varied within 0.2–50.1 and 98.3–188.8 mg/m2 per hour, respectively, and correlated closely enough with the gas content in them. An approximate total methane emission
by the purification plants is about 475 kg per day and the major contribution (83%) belongs to the silt field sediments characterized
by its extremely high content (42.42–199.49 μg/g of the damp sediment). It is demonstrated that the regression equations obtained
by the authors before and approximating the relation of the methane content in the water and bottom deposits of water bodies
with its fluxes to the atmosphere can be used to estimate the methane amount emitted during the waste water purification. 相似文献
9.
Russell Seitz 《Climatic change》2011,105(3-4):365-381
Because air?Cwater and water?Cair interfaces are equally refractive, cloud droplets and microbubbles dispersed in bodies of water reflect sunlight in much the same way. The lifetime of sunlight-reflecting microbubbles, and hence the scale on which they may be applied, depends on Stokes Law and the influence of ambient or added surfactants. Small bubbles backscatter light more efficiently than large ones, opening the possibility of using highly dilute micron-radius hydrosols to substantially brighten surface waters. Such microbubbles can noticeably increase water surface reflectivity, even at volume fractions of parts per million and such loadings can be created at an energy cost as low as J m???2 to initiate and mW m???2 to sustain. Increasing water albedo in this way can reduce solar energy absorption by as much as 100 W m???2, potentially reducing equilibrium temperatures of standing water bodies by several Kelvins. While aerosols injected into the stratosphere tend to alter climate globally, hydrosols can be used to modulate surface albedo, locally and reversibly, without risk of degrading the ozone layer or altering the color of the sky. The low energy cost of microbubbles suggests a new approach to solar radiation management in water conservation and geoengineering: Don??t dim the Sun; Brighten the water. 相似文献
10.
A. F. G. Jacobs B. G. Heusinkveld J. P. Nieveen 《Theoretical and Applied Climatology》1998,59(1-2):121-127
Summary For many biological processes, the daily and seasonal behavior of the temperature of the water layer close to the water surface
is very important. An example is the development of larvas of mosquito species which develop in small still water bodies.
An outdoor experiment during a summer period of four months has been executed in a small water body situated within a bog
area, in order to obtain insight into the daily and seasonal temperature behavior of this water body.
The measurements show that during daytime a strong thermal stratification occurs in the water body and that during nighttime
a well mixed layer develops growing from the water surface. In the upper water layer a well developed daily temperature cycle
is present. This cycle is strongly reduced by depth. On average, the daily maximum water temperature excursion from the mean
agree with the daily maximum air temperature excursion from the mean. The range between maximum and minimum water temperature
correlate well with the daily global irradiation.
Received February 14, 1996 Revised May 21, 1997 相似文献
11.
兰州市空中水汽含量和水汽通量变化研究 总被引：3，自引：0，他引：3
利用历年的高空和地面资料,深入分析了兰州市空中水汽含量和水汽通量的变化特征。结果表明:(1)夏季空中水汽含量和水汽输送相对较多,冬季相对较少;2~7月是水汽含量的增长期,9~1月是递减期,8月与7月持平;97%的水汽集中在400 hPa以下;(2)兰州市空中水汽变化与降水量、降水日数、气温的变化有明显的一致性,也存在一定的差别;(3)兰州市空中水汽输送强度中心接近500hPa高度;冬季水汽日变化最大层位于700~600 hPa,这与我国东部地区空中水汽输送高度和边界层水汽日变化特征有明显的区别。 相似文献
12.
地表非均匀性对区域平均水分通量参数化的影响 总被引：3，自引：3，他引：3
次网格尺度地表非均匀性对于网格区平均通量具有重要影响。若将网格区视为均一地表 ,并不能真实描述地 气通量交换过程 ,且可造成很大误差。文中从理论上证明 ,区域平均水分通量的变化率可分解为两部分 :第一部分为区域水分通量的算术平均变化率 ;第二部分为非均匀性所引起的水分通量变化率扰动 ,它与区域内土壤水分空间分布的变差系数有关。数值试验表明 ,地表土壤水分的水平空间变差系数集中反映了区域内土壤水分分布的非均匀程度 ,不同土壤对同样的非均匀程度其敏感性是不同的。变差系数愈大 ,非均匀性愈强 ,在相同的土壤水分平均值下 ,不同土壤类型对地表非均匀程度的敏感性并不相同。例如沙土和粘土受非均匀性的影响就可相差数十倍。 相似文献
13.
The POMRad system of computer models is developed using the Princeton Ocean Model (POM) program code. The system enables modeling the radionuclide migration in large nonuniform water bodies (seas, bays, large rivers, and lakes) taking account of the migration of radioactive substances in the water mass-bottom system associated with the migration of radionuclides sorbed on suspended sediments and in solutes. In order to take account of radionucide transport with sediments the POM program code is supplemented with the models describing transport, settling, and resuspension of suspended sediments. The verification was carried out through comparing analytical solutions of simplified problems concerning the content of radionuclides in water, and modeling results. A potential of the POMRad application is demonstrated by an example of simulating the radioactivity transport in marine environment in the case of hypothetical accidents in the Saida and Kola bays. 相似文献
14.
A model for pollutant redistribution in the soil-atmosphere system is suggested for the case of the local pollution of the underlying surface. The vertical migration of soil pollution is described with a convection-diffusion equation in the sorbing medium, supposing an instantaneous equilibrium is established between the pollutant phases in the soil. The Monin-Obukhov similarity theory for the surface atmospheric layer, modified for the case of limited pollution of the underlying surface, is used to parametrize the pollutant transport and dispersion in the atmosphere. A characteristic feature of the model is its ability to calculate the air pollution concentrations over the polluted soil surface. The model was tested on the results of a field experiment with volatile pesticides. 相似文献
15.
利用青藏高原北麓河观测站（退化高寒草甸）和玛曲观测站（高寒草原）2014年地面观测资料,通过组合分类法,对比分析了两类下垫面生长季土壤含水量、水汽压差和净辐射对地表能量分配的直接影响和间接影响,并且利用路径分析法研究了影响地表能量分配的关键气候因子。结果表明:北麓河站和玛曲站潜热占比（潜热通量与地表可利用能量的比值）对土壤含水量的响应分别处于土壤水分抑制阶段和能量抑制阶段。其中,北麓河站潜热占比在水汽压差较大时随土壤含水量增长较快,受净辐射的影响较小;而玛曲站潜热占比随土壤含水量的变化趋势受水汽压差和净辐射的影响均较小。北麓河站潜热占比随水汽压差的增大先减小后趋于不变,并且潜热占比对水汽压差的敏感性随土壤含水量的增大而减小;而玛曲站潜热占比随水汽压差的增大先增大后趋于不变,几乎不受土壤含水量和净辐射的影响。北麓河站和玛曲站潜热占比均随净辐射的增大趋于稳定,其稳定值分别与土壤含水量和水汽压差有关。路径分析结果显示,降水是影响北麓河站潜热占比的主要气候因子,而气温是影响玛曲站潜热占比的主要气候因子。 相似文献
16.
The present research is based on the annual Reviews of Environmental Conditions and Pollution in the Russian Federation and Yearbooks of Environmental Pollution in the Russian Federation for the period of 2006-2015. The parameters and estimates of abiotic environmental component (air, surface water, and soil) and radiation conditions are generalized from the data of the national observation system of environmental conditions (a base of the national system of environmental pollution monitoring in the Russian Federation) as well as from the data of local environmental observation systems. The results of the analysis of observational data and the conclusion on the conservation of high levels of air pollution in the cities and surface water pollution in many water bodies (including the assessment of priority of existing problems) are an important element of the informational support of state control of the sources of pollutant emissions (discharges) to the environment. The given information is also used for the comprehensive assessment of the influence of unfavorable environmental factors on the population health and terrestrial and water ecosystems. Besides, information on the dynamics and actual levels of environmental pollution allows assessing the efficiency of nature protection measures taking into account the observed trends and dynamics of variations. 相似文献
17.
青藏高原复杂下垫面能量和水分循环季节变化特征分析 总被引：2，自引：2，他引：0
为深入认识青藏高原能量和水分循环季节变化,利用GSWP(Global Soil Wetness Project)、GLDAS(Global Land Data Assimilation System)、AMSR-E(Advance Microwave Scanning Radiometer-EOS)土壤湿度以及台站观测资料等多种数据,采用滑动t检验初步分析高原下垫面各物理量季节变化特征。结果表明:各物理量季节变化特征明显且联系密切。高原下垫面净短波辐射和感热通量在1月中旬显著开始增加,5~6月达到全年最高值。净长波辐射5月表现为高值,夏季表现为低值。地表潜热通量在1月显著开始增加,在夏季达到全年最高值。表层土壤3月开始输送热量到大气,9月大气开始向土壤表层传递热量;融雪3~5月加快,雪盖减少。降水和1 cm植被含水量在2月显著开始增加,1 cm土壤显著开始加湿,5~6月降水陡增,1 cm土壤湿度表现为峰值。1 cm植被含水量、植被蒸腾、总蒸散与降水在7~8月达全年最高值,1 cm土壤湿度在7月表出现为谷值,9月达全年第二峰值。10月下垫面温度转冷后,雪盖增加,土壤湿度逐渐减小。 相似文献
18.
受气候增暖和人类活动的双重影响,黄河流域的水循环正在发生显著变化,水资源供需矛盾突出。陆地水循环是一个复杂的非线性系统,为清晰认识水循环变化的全貌,并合理高效利用有限的水资源量,需要综合考虑水循环各个要素之间的协同变化机制。同时,在“人类世”背景下,黄河流域水循环研究必须考虑人类活动的影响,主要包括植被变化和人类用水,其中人类用水主体为农业灌溉。自从实施生态恢复工程以来,黄土高原植被覆盖明显改善的同时也引发了对径流、蒸散发、降水、土壤湿度以及地下水的一系列影响,且研究结论还存在一些争议,但黄土高原植被覆盖改善使得该地区蒸散发量增加基本达成共识,大多数研究支持植被改善减少径流的结论。黄河流域的农业灌溉方式主要为大水漫灌,其对地表蒸散发、地表水及地下水多个过程具有重要影响。本文主要针对黄河流域的水循环研究,讨论相关研究进展以及发展方向。 相似文献
19.
利用青海省甘德两次降雪过程的微气象观测数据,探讨了两场降雪过程雪深、雪密度、雪中含冰量、雪中含水量和雪面温度的变化情况,分析了地表反照率与雪密度、雪中含冰量及雪中含水量的关系,结合降雪过程近地面温、湿、风廓线特征分析了积雪对近地面温、湿、风梯度的影响。结果表明:积雪覆盖会导致地表反照率显著增加,降雪过后正午时地表反照率可高达0.8～0.9。随着积雪的消融,地表反照率逐渐减小;积雪反照率与雪密度和雪中含冰量呈正相关,与雪中含水量呈负相关;地表积雪覆盖会导致近地面温度梯度绝对值减小,相对湿度梯度绝对值在凌晨减小、午后增大,地表积雪覆盖对近地面风速梯度变化并无特定的影响。 相似文献
20.
Alpine wetland is one of the typical underlying surfaces on the Qinghai–Tibet Plateau. It plays a crucial role in runoff regulation. Investigations on the mechanisms of water and heat exchanges are necessary to understand the land surface processes over the alpine wetland. This study explores the characteristics of hydro-meteorological factors with in situ observations and uses the Community Land Model 5 to identify the main factors controlling water and heat exchanges.Latent heat flux and therm... 相似文献