Cropland Riparian Buffers throughout Chesapeake Bay Watershed: Spatial Patterns and Effects on Nitrate Loads Delivered to Streams

We used statistical models to provide the first empirical estimates of riparian buffer effects on the cropland nitrate load to streams throughout the Chesapeake Bay watershed. For each of 1,964 subbasins, we quantified the 1990 prevalence of cropland and riparian buffers. Cropland was considered buffered if the topographic flow path connecting it to a stream traversed a streamside forest or wetland. We applied a model that predicts stream nitrate concentration based on physiographic province and the watershed proportions of unbuffered and buffered cropland. We used another model to predict annual streamflow based on precipitation and temperature, and then multiplied the predicted flows and concentrations to estimate 1990 annual nitrate loads. Across the entire Chesapeake watershed, croplands released 92.3 Gg of nitrate nitrogen, but 19.8 Gg of that was removed by riparian buffers. At most, 29.4 Gg more might have been removed if buffer gaps were restored so that all cropland was buffered. The other 43.1 Gg of cropland load cannot be addressed with riparian buffers. The Coastal Plain physiographic province provided 52% of the existing buffer reduction of Bay‐wide nitrate loads and 36% of potential additional removal from buffer restoration in cropland buffer gaps. Existing and restorable nitrate removal in buffers were lower in the other three major provinces because of less cropland, lower buffer prevalence, and lower average buffer nitrate removal efficiency.     

高压环境下2种NDIR型CO_(2)红外传感器的响应规律

目的研究压力变化环境对NDIR型CO_(2)气体传感器的影响,获得不同压力范围内传感器的响应变化规律。方法采用小型加压舱,在CO_(2)分压不变的情况下,分别采用N_(2)阶梯缓慢加压和冲击快速加压方式,研究英国C20和国产G4传感器在高压环境中稳定时间和漂移度等性能指标的波动规律,考察传感器对压力变化的响应规律。结果在低于607950 Pa的高气压稳压状态下,基本不会造成机械损伤,但信号会发生较大的漂移,国产G4分体式传感器出现信号震荡现象。CO_(2)分体式传感器及整机的浓度输出值随着压力的升高,标准气样值与实测值的比值接近幂函数形式,分体式传感器的输出浓度值比整机的输出浓度值要大。结论不同CO_(2)浓度分压下的压力响应规律具有比较良好的一致性,冲击加压的漂移比阶梯加压显著,浓度真值可以通过测量总压和内置多次函数来修正。     

中国国土空间规划法律体系：问题检视与框架重构

通过对现行空间规划法律规范的体系性检视,发现由于立法策略、部门立法以及规划立法依附性等原因,其存在顶层立法付之阙如、外部结构冗杂扁平、内部规范碎片冲突等问题。遵循领域法、发展法以及体系化逻辑,国土空间规划立法应以现实问题与治理现代化为导向,在突破部门法壁垒的同时注重法制发展的接续性,力求实现国土空间规划法律体系的形式协调与价值融贯。构建国土空间规划法律体系,对内应确立国土空间规划法的基本法地位并辅之以配套立法,对外应注重与国土空间开发保护法等相关立法、国土空间政策与技术标准的衔接,最终构架起一个主轴明确、层次严密、差序有别的圆锥状国土空间规划法律体系。     

Prevention and cleanup of dynamic harm under environmental liability

This paper explores incentives for accident prevention and cleanup when firms are subject to environmental liability. In our two-period setup, the level of environmental harm in the second period depends on first-period harm when cleanup was incomplete. Under strict liability, in the first period, firms with a positive probability of going out of business before the second period have inadequate prevention and cleanup incentives. The fundamental disconnect between private incentives and social optimality cannot be remedied by using a multiple of harm as the level of compensation. Under negligence with a causation requirement, incentive problems remain; however, under negligence without such a requirement, first-best incentives may emerge, and using a multiple of harm as the level of compensation can ensure the efficient solution.     

珠江三角洲区域一体化的水利政策法规体系研究

建立珠江三角洲区域一体化的水利政策法规体系是珠江三角洲国民经济社会发展和水利现代化建设的需要。从珠江三角洲地区现行水利政策法规存在的问题入手,开展珠江三角洲区域一体化的政策法规体系研究。结果表明：珠江三角洲地区现行水利政策法规体系仍很不完善,许多立、改、废工作亟待进行,2008年水政执法有效率总体较高,但很少在珠江三角洲层面开展区域一体化的联合执法,珠江三角洲水利政策法规体系建设应重点加强与水利现代化建设、水资源一体化配置、保护及管理相关的政策法规,进而建立统一协调、快速高效的区域一体化的联合执法体系。     

Recovery of Endemic Dragonflies after Removal of Invasive Alien Trees

Abstract:  Because dragonflies are very sensitive to alien trees , we assessed their response to large-scale restoration of riparian corridors. We compared three types of disturbance regime—alien invaded , cleared of alien vegetation , and natural vegetation (control)—and recorded data on 22 environmental variables. The most significant variables in determining dragonfly assemblages were percentage of bank cover and tree canopy cover , which indicates the importance of vegetation architecture for these dragonflies. This finding suggests that it is important to restore appropriate marginal vegetation and sunlight conditions. Recovery of dragonfly assemblages after the clearing of alien trees was substantial. Species richness and abundance at restored sites matched those at control sites. Dragonfly assemblage patterns reflected vegetation succession. Thus , initially eurytopic , widespread species were the main beneficiaries of the removal of alien trees , and stenotopic , endemic species appeared after indigenous vegetation recovered over time. Important indicator species were the two national endemics ( Allocnemis leucosticta and Pseudagrion furcigerum ) , which , along with vegetation type , can be used to monitor return of overall integrity of riparian ecology and to make management decisions. Endemic species as a whole responded positively to restoration , which suggests that indigenous vegetation recovery has major benefits for irreplaceable and widespread generalist species .     

Assessing the P fractionation in a tropical river-estuarine system of South India

Seasonal variations in dissolved and particulate P forms were assessed in the estuarine system of Chalakudy River, Kerala, South India – a tropical river having substantial relics of riparian vegetation. The contribution of the reactive P form extended to 84–96% compared with the residual fraction. Geographical and human activities have had effects on the phosphorus-loading capacity at various locations, which reveal pronounced variability in P distribution. Not all forms of phosphate in suspended particulate matter are likely to be released, and thus the nature of the P forms within the stock is a sensitive factor that can be utilised. Ca-bound P in suspensates increases to a highly significant level in the estuarine area, whereas Fe/Al-bound P predominates at the riverine and catchment areas during both the monsoon and non-monsoon seasons. Thus, calcium compounds determine the availability of P in the alkaline estuarine environment, whereas in the riverine environment, Al and Fe control P solubility. The comparatively low P load in upstream waters indicates that, under ambient situations, vegetative riparian zones can be very important P filters.     

Effects of riparian land use on water quality and fish communities in the headwater stream of the Taizi River in China

Riparian land use remains one of the most significant impacts on stream ecosystems. This study focuses on the relationship between stream ecosystems and riparian land use in headwater regions. Four riparian land types including forest, grassland, farmland, and residential land were examined to reveal the correlation between stream water and fish communities in headwater streams of the Taizi River in north-eastern China. Four land types along riparian of 3 km in length were evaluated at 25, 50, 100, 200 and 500 m widths, respectively. Generally, the results found a significant relationship between riparian land uses and stream water quality. Grassland was positively correlated with water quality parameters (conductivity and total dissolved solids) at scales from 100 to 500 m riparian width. Farmland and residential land was negatively correlated with water quality parameters at scales from 25 to 500 m and from 50 to 200 m riparian widths, respectively. Although the riparian forest is important for maintaining habitat diversity and fish communities, the results found that only fish communities were significantly correlated with the proportion of riparian farmland. Farmland had a positive correlation with individual fish abundance within a riparian corridor of 25 to 50 m, but a negative correlation with fish diversity metrics from 25 to 100 m. This study indicates that effective riparian management can improve water quality and fish communities in headwater streams.     

基于Android平台的安全生产移动执法系统实现

随着现代科技的发展,安全生产监督管理需要模式、方法、手段等方面实现创新.本文紧密结合安全生产监督管理工作的需要,以Android平台为基础,基于SOA架构设计,采用第三代移动访问技术,融合无线通信、数据库及计算机网络等前沿技术,研究开发了一套安全生产移动执法系统,它包含了移动执法端、服务管理端和底层通信服务三大体系,实现了安全生产现场执法各项功能,有效推进了移动通信技术在安全生产领域的应用.     

陕西省煤矿瓦斯综合治理探讨

节约发展、清洁发展、安全发展是构建社会主义和谐社会的必然要求。我国目前煤矿安全生产形势趋稳向好,但依然严峻。分析陕西省煤矿瓦斯灾害情况和近年来煤矿安全生产状况。总结分析近年来我省瓦斯综合治理取得的成效,煤矿监察执法方面所做的主要工作,煤矿瓦斯综合治理存在的一些问题,提出一些针对性的建议和工作措施。