Hedgerows and hedgerow networks in landscape ecology

Hedgerows originated and coexist with agriculture. Their internal structure and species diversity vary widely with origin (planted, spontaneous, or remnant), farming practices in adjacent fields, and the refined art of hedgerow management. Most hedgerow species are forest-edge species, and apparently none is limited to hedgerows. Wide hedgerows composed of trees and shrubs appear to function as corridors for movement of many plants and animals across a landscape. The reduction of crop loss, by dampening pest population fluctuations with hedgerow predators, remains a hypothesis for study.Field microclimate downwind of a hedgerow is modified about 16 times the hedgerow height (h) for evaporation, and approximately 28 h for wind speed. A turbulent wind pattern with harsher microclimate is present at 6–8 h if a second hedgerow is nearby downwind. Zones of higher crop productivity at 3- to 6-h downwind, and 2- to 6-h upwind of a second hedgerow may be expected. Overall, we expect little short-term difference in farm-field production with or without hedgerows.Evidence suggests that hedgerow networks, and especially their mesh size (of fields), exert a major control on many major landscape fluxes. Such fluxes include animal populations, wind speed, evapotranspiration and soil desiccation, soil erosion and nutrient runoff, species movement along network lines, and movement of field species across the network. In a relatively short period, the hedgerow ecosystem, with no unique species, has attained a metastable equilibrium, which is regulated by enormous human inputs.More than 20 economic roles of hedgerows are pinpointed. The roles, providing resources and protection of resources, are poorly known quantitatively. We conclude that hedgerows perform diverse functions for society and the farmer that are both economically and ecologically significant.     

Development of a Model for Simulation of Solute Transport in a Stream–Aquifer System

A model for simulation of solute transport in a dynamic stream–aquifer system is developed by integrating four existing sub-models. Interface packages are created to link the sub-models. The developed model is successfully used to simulate chloride transport in the stream–aquifer system of the Arkansas River and the Equus Beds Aquifer in Kansas and demonstrates that chloride concentration in the aquifer decreases in the vicinity of the simulated channel over time.     

Interaction Between GSM Handset Helical Antenna and User's Head: Theoretical Analysis and Experimental Results

Summary The performance of a cellular phone commercial helical antenna at 900~MHz band, both in free space and in the presence of a human head phantom was studied. Numerical simulation of the phone model for the latter case has been performed giving 3D radiation diagrams. The effect of the phantom head on radiation diagrams is presented. The relative amount of the EM power absorbed in the head was obtained for several distances of the phone. Measurements were carried out in a RF anechoic chamber using standard horn antennas and a calibrated measuring system. Absolute radiation patterns of the antenna gain were obtained in the three principal planes. Significant reduction of the absorbed power could be achieved just by moving the phone 1 cm away from the head.     

永定河生态补水下渗对地下水质量的影响

以永定河北京段2019～2020年的生态补水为例,通过室内混合实验和淋滤实验研究河水下渗对地下水质量的影响.结果表明,水化学指标的种类与下渗前相比无变化,水-岩相互作用对指标浓度的改变作用也比较有限,指标的浓度水平总体上介于河水和地下水之间.下渗水对地下水质量的改变作用从根本上取决于河水与地下水的质量差异和河水的补给量...     

多种农药对胎儿发育的联合作用分析

分析了应城农村１２万确定人群中１９８８－１９８９年２年期间出现妊娠出现妊局的妇女的前瞻性流行病学调查资料。共调查了５６７４位妇女。按照期家中使用的药品种数目,将研究对象分为０、１、２、３、４、５、≥和总组,计算了各组发生各种不良妊娠结局的相对度,结果表明。所暴露的农药品种数愈多,发生自然流产和出生缺陷的危险度愈大。农药品种数与它们对胎儿发育的不良影响之间存在“剂量－效应关系”。由此得出结论;多种农     

Information presentation compatibility in a simple digital control panel design: eye-tracking study

Various designs of typical digital control panels were analyzed experimentally from both the effectiveness and efficiency points of view. Subjects performed information comparison tasks aimed at keeping vehicle velocity at the same level. The experiment involved two versions of speedometers for displaying current and target velocities (clock-face and digital). The stimuli were also differentiated by the target velocity value (20, 50 and 80?km/h) and the correct response type (increase or decrease). Subjects’ performance results along with the eye-tracking data were qualitatively and quantitatively analyzed for all 24 experimental conditions.     

Impacts of Variable Climate and Effluent Flows on the Transboundary Santa Cruz Aquifer

Assessing groundwater resources in the arid and semiarid borderlands of the United States and Mexico represents a challenge for land and water managers, particularly in the Transboundary Santa Cruz Aquifer (TSCA). Population growth, residential construction, and industrial activities have increased groundwater demand in the TSCA, in addition to wastewater treatment and sanitation demands. These activities, coupled with climate variability, influence the hydrology of the TSCA and emphasize the need for groundwater assessment tools for decision‐making purposes. This study assesses the impacts of changes in groundwater demand, effluent discharge, and climate uncertainties within the TSCA from downstream of the Nogales International Wastewater Treatment Plant to the northern boundary of the Santa Cruz Active Management Area. We use a conceptual water budget model to analyze the long‐term impact of the different components of potential recharge and water losses within the aquifer. Modeling results project a future that ranges from severe long‐term drying to positive wetting. This research improves the understanding of the impact of natural and anthropogenic variables on water sustainability, with an accessible methodology that can be globally applied.     

中美大气污染的空间交互影响--来自国家和城市层面PM2.5的经验证据

准确识别中美大气污染的空间交互影响可以为两国在大气污染治理领域开展双边合作提供科学依据。以PM 2.5浓度表征大气污染程度,采用收敛交叉映射(Convergent Cross Mapping,CCM)方法,在采集伯克利地球发布的小时数据的基础上通过算数平均得到2018年1月1日至2018年12月31日的PM 2.5浓度日均数据,从国家和城市两个层面识别了中美大气污染的空间交互影响。研究发现,中美两国的大气污染是空间交互影响的。其中,国家层面,在CCM因果检验基础上的广义同步检验表明,在1%显著性水平上,大气污染仅存在由美国指向中国的单向因果关系。城市层面,中美两国10个样本城市之间理论上共存在50个可能的因果关系(5×5×2)。研究发现,在1%显著性水平上,美国城市指向中国城市的因果关系有12个,而中国城市指向美国城市的因果关系仅有5个。在影响强度上,美国城市的大气污染对中国城市的影响强度高于中国城市的大气污染对美国城市的影响强度,如重庆的大气污染对华盛顿的影响强度为0.21,而华盛顿的大气污染对重庆的影响强度为0.35。面对大气污染的空间交互影响,中美两国可通过积极开展联合科研攻关,厘清大气污染的传输路径及其驱动因素,进行污染物的联合监测与数据管理;通过共享大气污染治理技术和建立大气污染防治基金等方式,加强在大气污染治理领域的合作。一旦中美两国成功建立起大气污染双边合作治理体系,依靠两国的国际地位和国际影响力,必将吸引越来越多的国家参与进来共同行动,大气污染全球治理体系的构建将非常值得期待。     

钻井废水的生物强化处理简

从受钻井废水污染的土壤样品中筛选菌株进行生物处理实验,确定7株菌进行菌剂配伍。通过正交实验剔除可能有抑制作用的菌株,并确定菌剂各组成菌株的最佳配比,制成复合微生物菌剂。考察5种添加物对菌剂的影响,结果显示,当硫酸铵的添加量为20 mg/L时降解率为60%,高于其他添加物。生物强化实验结果显示,投加菌剂的反应器对钻井废水的平均降解率为42%,比未投加菌剂的对照实验的平均降解率（16%）高,而且耐冲击负荷性和降解性能稳定性优于对照实验。     

Algae mediate submerged macrophyte response to nutrient and dissolved inorganic carbon loading: A mesocosm study on different species

Nutrient and dissolved inorganic carbon are two important factors that influence the development and species composition of submerged macrophyte communities in shallow lake ecosystems. Yet little is known about their potential interactive effects on the submerged macrophytes and competition outcome of macrophyte–phytoplankton. We performed a mesocosm experiment to investigate the growth and photosynthetic performance of three submerged macrophytes in relation to phytoplankton/epiphyton with nutrient and bicarbonate enrichment. During the experimental period (42 d), increase in nutrient loading in water column resulted in a substantial burst of phytoplankton and epiphyton growth and increased light attenuation. When combined with nutrient loading, bicarbonate enrichment also resulted in a heavily phytoplankton- and epiphyton-dominated state, although bicarbonate enrichment per se does not cause the phytoplankton and epiphyton growth. However, increase in nutrient loading in water column had significant negative impact on individual performances (growth and photosynthesis) of the three submerged macrophytes and bicarbonate enrichment increased the effect of eutrophication on two dissected-leaf macrophytes (M. spicatum and E. nuttallii). Furthermore, our results also suggest that species-specific photosynthetic performances occurred when submerged macrophytes in an environment with high abundance of phytoplankton/epiphyton. This study highlighted that increase in nutrient loading and bicarbonate in water column is likely to interactively impact both abiotic and biotic properties of a freshwater ecosystem. The interactions of these two factors could select macrophyte species that are able to resist the shading from phytoplankton/epiphyton, making these species more dominant in natural freshwater ecosystems.