USE OF HEMISPHERIC IMAGERY FOR ESTIMATING STREAM SOLAR EXPOSURE1

ABSTRACT: Solar exposure profoundly affects stream processes and species composition. Despite this, prominent stream monitoring protocols focus on canopy closure (obstruction of the sky as a whole) rather than on measures of solar exposure or shading. We identify a candidate set of solar exposure metrics that can be derived from hemispheric images. These metrics enable a more mechanistic evaluation of solar exposure than can be achieved with canopy closure metrics. Data collected from 31 stream reaches in eastern Oregon enable us to quantify and compare metrics of solar exposure from hemispheric images and a metric of canopy closure with a concave densiometer. Repeatability of hemispheric metrics is generally as good as or better than the densiometer closure metric, and variation in the analysis of hemispheric images attributable to differences between analysts is negligibly small. Metrics from the hemispheric images and the densiometer are typically strongly correlated, at the scale of an individual observation and for 150 m stream reaches, but not always in a linear fashion. We quantify the character of the uncertainty in the relationship between the densiometer and the hemispheric metrics. Hemispheric imagery produces repeatable metrics representing an important ecological attribute; thus those researching the effects of solar exposure on stream ecosystems should consider the use of hemispheric imagery.     

山东省海水入侵灾害危险性评价的GIS方案设计

以山东省为例，利用GIS技术建立了一套海水入侵灾害危险性评价信息系统。通过对多因素的综合分析，获取了各评判单元海水入侵灾害综合危险性指数，求得了各地海水入侵的平均距离，从而实现了山东省海水入侵灾害危险性区划，并能以地图或数据的形式快捷的显示处理结果。     

天津市滨海地区综合防灾减灾的策略研究

分析了天津市滨海地区历史自然灾害的历史和特点，预测了该地区未来一段时间和最近1－2年可能发生的主要自然灾害，提出了本区综合防灾减灾的策略和目标，为该区综合防灾减灾规划的制订提供了依据。     

Assessment of Lead Exposure in Thohoyandou, South Africa

Lead levels in different environmental media (soil, grass leaves, water, ceramics, pencil, paint, crayons and cosmetics) were determined to assess the major sources of lead exposure in Thohoyandou, South Africa. Soil and plant leaves were used as indicators of Pb pollution from vehicle exhaust emissions. After digestion with concentrated acids (HNO₃, HCl and HClO₄) Pb concentrations were determined in triplicate using a flame atomic absorption spectrometer. The mean Pb concentrations at the kerb of selected busy roads were 205.5 ± 90, 273.0 ± 90 and 312.8 ± 81 μg g⁻¹ and 154.7 ± 67, 182.9 ± 76 and 240.6 ± 66 μg g⁻¹ for soil and plant leaves (dry weight) respectively. These concentrations were substantially higher than the values found on soils 50 m away from the roads (97.4 ± 11 μg g⁻¹). Pb concentrations in plants collected further away from the road (50 m) were substantially lower (71.8 ± 9.0 μg g⁻¹). The observed levels on soil are lower than the UK critical value of 500 μg g⁻¹ for gardens and allotments; and 2000 μg g⁻¹ for parks and open space as well as the Canadian values for agricultural (375 μg g⁻¹), residential (500 μg g⁻¹ and industrial (1000 μg g⁻¹). From these data it was clear that Pb concentrations in soil samples were substantially higher than the levels obtained for plant leaves. The Pb levels in green crayons, blue crayons, pencils (from China & Germany), were 10650 ± 75.2, 8200 ± 52.4, 1160 ± 50.2, 79 ± 10.1 μg g⁻¹ for the inner contents; and 4870 ± 58.1, 5650 ± 55.5, 1950 ± 46.6, 60 ± 12.9 μg g⁻¹ for the outer surface paint respectively. The ceramics showed Pb levels of 630 ± 50.3 μg g⁻¹ (saucer) and 560 ± 32.2 μg g⁻¹ (cup), while the inner contents and outer surface paint showed 480 ± 32.4 and 318 ± 21.2 μg g⁻¹ of Pb respectively. Early morning tap water flush gave a Pb level of 20.6 ± 5.6 μg Pb l⁻¹. This value is higher than the WHO and FDA maximum permissible concentrations of 10 μg l⁻¹ and 15 μg l⁻¹ respectively.     

Cardiovascular risk under electromagnetic exposure in physiotherapy

The aim of the study was to assess the long-term effects of electromagnetic radiation (EMR) on cardiovascular system of medical staff in physiotherapy. A number of 52 exposed subjects (4 male and 48 female; aged 47.3 ± 8.7 years), and a control group of 52 subjects, matched by sex and age, with similar job characteristics without EMR exposure were studied. The EMR exposure from devices emitting at 50 Hz, 150 kHz, 27.12 MHz, 2.45 GHz, and optical radiation was assessed. The relative values of EMR for the whole frequency range in each physiotherapy were calculated and the obtained quota was much larger than 1. The workload and psychosocial factors were evaluated, too. The cardiovascular risk factors arterial pressure, lipid profile, body mass index, waist/hip ratio, smoking, alcohol consumption, nutrition, family history of cardiovascular disease were studied. The incidence of hypertension was moderate with the studied physiotherapists (26.9% v.s. 23.8% control group). The total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) were significantly higher in the exposed group. The odds ratios indicate higher possibility of becoming dyslipidemic for the exposed to EMR subjects [for TC OR (95% CI) = 1.570 (1.048–2.351) and for LDL-C OR (95% CI) = 1.840 (1.158–2.924)]. In conclusion, our data show that the EMR exposure of the medical staff in physiotherapy could be associated with the adverse effects on cardiovascular system.     

职业噪声暴露测量方法探讨

噪声暴露是声压级与作用时间的综合结果。出于对听力保护的目的,积极推行声暴露的测量方法十分必要。本文通过对等效连续A计权声级、噪声暴露量、噪声剂量的测量和换算提出了对现行标准的理解和应用。     

EVALUATION OF THE APPLICABILITY OF THE SWAT MODEL FOR COASTAL WATERSHEDS IN SOUTHEASTERN LOUISIANA1

ABSTRACT: The Soil and Water Assessment Tool (SWAT) has been used for hydrologic analyses at various watershed scales. However, little is known about the model's performance in coastal watersheds. In this study SWAT was evaluated for its applicability in three Louisiana coastal watersheds: the Amite, Tickfaw, and Tangipahoa River watersheds. The model was calibrated with daily discharge from 1976 to 1977 and validated from 1979 to 1999 for the Amite and Tangipahoa and with daily discharge from 1979 to 1989 for the Tickfaw. Deviation of mean discharge and the Nash‐Sutcliffe model efficiency were used to evaluate model behavior. The study found that Manning's roughness coefficient for the main channel, SCS curve number, and soil evaporation compensation factor were the most sensitive parameters for these coastal watersheds. The Manning's roughness coefficient showed the greatest effect on the response time of surface runoff, suggesting the critical role of channel routing in hydrologic modeling for lowland watersheds. The SWAT model demonstrated an excellent performance, with Nash‐Sutcliffe efficiencies of 0.935, 0.940, and 0.960 for calibrations of the Amite, Tickfaw, and Tangipahoa watersheds, respectively, and of 0.851, 0.811, and 0.867 for validations. The modeling results demonstrate that SWAT is capable of simulating hydrologic processes for medium scale to large scale coastal lowland watersheds in Louisiana.     

综合自然灾害风险管理--全面整合的模式与中国的战略选择

综合自然灾害风险管理是目前国际上防灾减灾和灾害管理较先进的措施和模式，是针对各种自然灾害的全灾害的管理，是贯穿于灾害管理全过程，集中于灾害风险和承灾体脆弱性分析并强调多层面、多元化和多学科参与合作的全面整合的灾害管理模式。介绍了综合自然灾害风险管理的必要性、概念和本质，探讨了综合自然灾害管理的基本理论、对策及其实施过程和实施战略，在此基础上提出了对我国实施综合自然灾害风险管理的建议，为强化和推动我国综合自然灾害风险管理提供参考。     

黄河三角洲滨海湿地的区域自然灾害风险

黄河三角洲是中国典型的滨海河口湿地，具有重要的生态和经济意义。该区域自然灾害频繁，海岸侵蚀、海面上升、风暴潮和黄河断流等主要灾害风险因子之间密切相关。在它们的共同作用下，黄河三角洲滨海湿地面积不断减少，地表结构遭到破坏，生态特征发生改变，生态环境持续恶化，导致滨海湿地不断损失和退化。应从系统的角度认识黄河三角洲滨海湿地与区域自然灾害的关系，科学对待并切实缓解滨海湿地的损失和退化。     

东部沿海地区农户非农就业对农地租赁行为的影响研究

非农就业后农户如何利用农地资源成为决定粮食安全与农民增收的关键。基于生产决策理论剖析了不同情境下农户非农就业对农地租赁行为的影响,并采用东部沿海地区599个农户调查数据进行了检验。结果表明:①有剩余劳动力与无剩余劳动力情景,农户非农就业对农地租赁行为的影响并不一致;②非农就业改变家庭要素禀赋结构与劳动力相对报酬,进而影响农地租赁行为;③东部沿海地区农地租赁行为响应是非农就业特征与外部环境综合作用的结果,其中非农就业规模、非农就业区位、非农就业逆向淘汰程度与农地租出行为呈正相关关系,从事第二产业的农户倾向于租出农地。非农就业规模的农地租赁行为响应存在门槛效应,而非农就业类型的总体影响较小。