秦巴山地西部地区2015—2018年大气污染物变化特征及潜在来源分析

为了研究我国南北过渡带西部地区大气污染物变化特征，选取了秦巴山地西部陇南市2015-2018年大气主要污染物监测资料和气象数据，分析了各污染物的浓度水平、变化特征及与气象条件的关系，并利用HYSPLIT后向轨迹模式分析了该地区污染物潜在来源（WPSCF和WCWT）.结果表明：4年来，秦巴山地西部地区空气环境质量较好，空气质量优良率达94.24%，6项大气污染物SO₂、NO₂、CO、O₃、PM_2.5、PM₁₀平均浓度分别为19.02、23.35、701.41、83.11、30.57、56.50 μg·m^-3，均未超过国家二级标准.PM₁₀是该地区首要污染物中天数最多的，达94 d.污染物SO₂、NO₂、CO、PM_2.5和PM₁₀的季节变化和日变化特征具有较好一致性，呈"U"型变化，O₃呈单峰型，在夏季和午后浓度到达高值.颗粒污染物PM₁₀、PM_2.5与气态污染物SO₂、NO₂、CO均呈现较好正相关，气温、降水量和风速风向对污染物浓度有较大的影响.该地区冬季空气质量明显差于其他季节，颗粒物浓度主要受供暖期化石燃料燃烧和外来气流的影响.     

1973-2018年布喀达坂峰地区前进冰川遥感监测

冰川跃动是冰川动力不稳定性的表现,影响着全球约1%的冰川。基于1973-2018年208景Landsat MSS/TM/ETM+/OLI遥感影像,对布喀达坂峰地区不同时期前进冰川进行遥感识别。结果表明：（1）1973-2018年布喀达坂峰地区共有7条冰川发生过前进,其中冰川末端快速退缩型冰川有3条,冰川末端波动前进型和冰川末端稳定型冰川各有2条。莫诺马哈冰川和5Y542H0020冰川可能为跃动冰川,且前者正处于跃动阶。（2）近45年间布喀达坂峰地区7条冰川共出现过25次前进现象,各条冰川发生前进次数均多于（含）2次;前进冰川发生时间主要集中于2000s（7次）和1970s（6次）。该地区冰川在各月份均发生过前进现象,推断该地区前进冰川属斯瓦尔巴型。布喀达坂峰地区冰川前进无明显规律,大多数冰川两次前进时间间隔为10年左右。（3）布喀达坂峰地区冰川前进可能受热控和水控机理共同作用,单一的气候变化尚难以解释其变化机理。     

西昆仑山黄土1 Ma 以来的粒度变化特征及其古气候意义

塔里木盆地南缘保存有中国西北地区厚度最大的黄土,是详细研究亚洲内陆极端干旱 区以及塔克拉玛干沙漠形成演化的理想材料。但是,目前对该地区黄土堆积粒度特征系统的研 究还相对较少,对粒度指标的古环境意义仍存有不同的认识。通过对207 m 黄土岩芯的粒度分 析发现,西昆仑山黄土的粒度组成比较均一,分选较好,主要以粗颗粒物质为主,细颗粒含量 极少,并具有典型的风成成因特征。此外,西昆仑山黄土粒度1 Ma 以来呈现出持续变粗的趋势。 通过与其他气候指标的对比,这种变粗的趋势可能主要反映了中更新世以来亚洲内陆逐步增强 的干旱化过程。     

Bacterial water quality: Springs and streams in the Great Smoky Mountains National Park

Water samples from streams and springs in the Great Smoky Mountains National Park were analyzed for fecal coliform, fecal streptococcus, and total coliform bacteria. Levels of bacteria were found to be highly variable but related to elevation, time of year, type of water source, and water level of the streams. Visitors did not seem to be major contributors to bacterial contamination. Levels of fecal coliform and total coliform in most water samples were unsuitable for drinking without treatment. Tennessee state standards for body contact recreation (swimming and wading) were exceeded in a few samples but none from streams suitable for swimming. As a result of these findings, park managers increased efforts to inform visitors of the need to treat drinking water and removed improvements at backcountry springs which tended to give the springs the image of safe, maintained water sources.     

Agricultural area impacts within a natural area: Cades cove,a case history

Agricultural management in Cades Cove, an historic district in Great Smoky Mountains National Park, has affected natural resources both within the district and in the adjoining natural areas. Aquatic impacts of haying and cattle grazing included increases in water temperatures, turbidity, nutrient loading, and bacterial counts and decreases in benthic macroinvertebrate density and fish biomass. Wildlife populations, including groundhogs, wild turkeys, and white-tailed deer, have increased in the open fields and around the periphery of the historic district. Intensive deer foraging has removed deciduous seedlings and saplings from woodlots, lowering species diversity and favoring coniferous reproduction. Cades Cove has limestone habitats unique in the park, and both deer browse and cattle grazing may have disturbed populations of rare plant species. Effects on water quality are detectable at a campground 15 stream km from the agricultural area, and the effects of deer foraging extend about 1 km beyond the open fields.Since historic landscape preservation is presently a goal of the park, managing for open vistas in Cades Cove will require some sort of continuing disturbance. Conversion of cattle pastures to hayfields would reduce aquatic impacts but the deer herd might increase as a result of reduced competition for forage. Retarding old field succession would increase populations of native plant species dependent on sunlight, but would require government-funded mowing. Other options are discussed. Completely eliminating the effects of the historic district on adjoining areas may be impossible, at least under present economic constraints.     

Stricter Ozone Ambient Air Quality Standard Has Beneficial Effect on Ponderosa Pine in California

Ambient air quality standards and control strategies are implemented to protect humans and vegetation from adverse effects. We used a process-based tree-growth model (TREGRO) to show that over the past 37 years, changes in O₃ exposure, with accompanying variation in climate, are reflected in changes in the growth of Pinus ponderosa Dougl. ex Laws. in the San Bernardino Mountains near Los Angeles, California, USA. Despite variation in temperature and precipitation over the study period (1963–1999), O₃ exposure consistently reduced simulated tree growth. Simulated growth reductions increased concurrent with increasing O₃ exposure. The maximum growth reduction occurred in 1979. As O₃ exposures decreased during the 1980s and 1990s, effects on growth also decreased. This implies that emission control strategies taken to reduce exposures to attain O₃ standards benefited P. ponderosa growth in the San Bernardino Mountains. This modeling approach provides a powerful tool for solving the difficult problem of evaluating regulatory effectiveness by simulating plant response using long-term climate and air pollution exposure records for a given region.Phone 541 754-4621 Fax 541 754-4799     

新疆天山北坡经济带生态环境保护思路探讨

随着区域经济的发展和自然资源的开发，区域生态环境状况面临严峻的考验。本文分析了新疆天山北坡经济带的生态环境现状、特点及发展趋势，重点阐述了该区域生态环境保护与治理的思路，并提出一些相应的对策和建议。     

Characteristics of winter backcountry use in Great Smoky Mountains National Park

Numerous backcountry and wilderness use studies have been conducted over the last decade, but nearly all of them have concentrated on peak season and summer use. This study investigates use patterns and user characteristics of winter campers, and implications for the management of winter backcountry overnight use. Use pattern data were collected from 580 backcountry use permits for both winter and summer campers of Great Smoky Mountains National Park (GSMNP). A two-page questionnaire was also mailed to 300 of the winter users to survey their characteristics, past backpacking experience, and reasons for winter camping. Backcountry permit data indicate that use patterns differ significantly between winter and summer campers, with winter campers taking shorter, weekend, destination-type trips. Winter campers engage in backcountry camping nearly twice as often during winter as other seasons of the year, both in and outside GSMNP. They are also experienced hikers that tend to avoid camping in Great Smoky Mountains National Park during the summer because of heavy visitor use. This suggests that winter backcountry campers are different enough from peak season campers that management of these two user groups may require different styles.     

RAINGAGE NETWORK DESIGN USING NEXRAD PRECIPITATION ESTIMATES1

ABSTRACT: A general framework is proposed for using precipitation estimates from NEXRAD weather radars in raingage network design. NEXRAD precipitation products are used to represent space time rainfall fields, which can be sampled by hypothetical raingage networks. A stochastic model is used to simulate gage observations based on the areal average precipitation for radar grid cells. The stochastic model accounts for subgrid variability of precipitation within the cell and gage measurement errors. The approach is ideally suited to raingage network design in regions with strong climatic variations in rainfall where conventional methods are sometimes lacking. A case study example involving the estimation of areal average precipitation for catchments in the Catskill Mountains illustrates the approach. The case study shows how the simulation approach can be used to quantify the effects of gage density, basin size, spatial variation of precipitation, and gage measurement error, on network estimates of areal average precipitation. Although the quality of NEXRAD precipitation products imposes limitations on their use in network design, weather radars can provide valuable information for empirical assessment of rain‐gage network estimation errors. Still, the biggest challenge in quantifying estimation errors is understanding subgrid spatial variability. The results from the case study show that the spatial correlation of precipitation at subgrid scales (4 km and less) is difficult to quantify, especially for short sampling durations. Network estimation errors for hourly precipitation are extremely sensitive to the uncertainty in subgrid spatial variability, although for storm total accumulation, they are much less sensitive.     

秦岭生态补偿理论研究与实践进展

生态补偿是通过经济手段促进生态保护与受益地区利益共享的制度设计,是促进我国生态文明建设的重要举措。秦岭是我国重点生态功能区,国家重要的生态安全屏障。生态补偿作为协调秦岭地区生态环境保护和社会经济发展的制度安排,有助于推动该区生态环境的保护与可持续利用,对实现秦岭地区社会经济可持续发展、促进人与自然和谐共生具有重要意义。本文系统梳理了秦岭生态补偿相关理论研究与实践,主要包括秦岭在区域调水、森林生态效益、生物多样性保护、矿产资源开发等方面的生态补偿研究,以及秦岭生态补偿相关政策法规制定、南水北调、退耕还林（草）以及生态移民搬迁等具体生态保护工程补偿实践,并从补偿对象、补偿标准、公众参与、补偿方式几个角度探讨了秦岭生态补偿存在的问题,提出了秦岭生态补偿研究的建议与对策。