北方典型农居环境空气中颗粒态汞的污染特征

近年来,我国农村环境问题日渐凸显,重金属污染是其中的一个重要方面。以往研究对于农居环境中的重金属污染状况关注很少,造成相关基础信息的缺失。以重要的重金属污染物——汞为研究对象,采集了我国北方3省夏季农户室内外空气和不同家用燃料排放的PM10样品,采用冷原子荧光法测定其中的颗粒态汞含量。结果表明,农户室内外空气中颗粒态汞浓度范围在27.6-727.2p^g/m3,平均为139.4 pg/m^3,高于国外乡村大气,但低于国内城市大气。室内空气中颗粒态汞的浓度受当地生活习惯和燃料类型的显著影响。不同燃料燃烧排放颗粒态汞的能力不同,从大到小依次为树根〉煤球〉树枝〉煤气〉作物秸秆。研究还发现,农作物不同部位燃烧排放颗粒态汞的能力差别很大;煤球充分燃烧时的排放显著高于焖烧时。对北方农居环境空气中颗粒态汞的健康风险进行了初步评价,结果表明成年人每周吸入的颗粒态汞占每周可耐受剂量的0.015%,对健康造成的风险较小,北方农村地区的汞污染防治可重点关注农业生产和乡镇企业排放等其他方面。     

草帘自动布草机的研制与试验

针对草帘编织行业人工铺草用工量大、工作环境恶劣、生产的草帘一致性差等问题,研制了一种草帘自动布草机。该机采用电动机和气动驱动,主要由小车总成、分草机构、压草机构和6个喂料斗组成,可以完成自动布草作业。现场生产试验表明:生产幅宽1 600mm的草帘,其厚度的均匀性≤18.87%,一致性好,表面平整,优于人工布草;生产速度达到了180m/h,减少用工4~6人,改善了工作环境,降低了劳动强度,对植物秸秆的再利用有积极的推动作用。     

粤港环境合作机制及其对我国其他区域环境合作的启示

随着经济的高速发展,我国的整体环境质量不断下降,跨界环境污染问题日益突出。跨界污染体现了污染的外部性特点及其与我国当前单一行政区划污染治理方式的矛盾,而行政区之间开展合作治理跨界污染是短期内以较小制度成本取得最优治理效果的合理选择,因此建立跨行政区的环境合作机制显得非常必要。粤港之间构建了有效的区域环境合作机制,在改善区域环境质量、治理跨界环境污染等方面取得了丰硕的成果。本文从组织架构、协议保障、管理手段和支撑体系建设四个方面对粤港环境合作机制进行深入剖析,并基于此对我国其他区域的跨行政区环境合作机制的建设提出建议。     

Effect of temperature and precipitation on nitrate leaching from organic cereal cropping systems in Denmark

The effect of variation in seasonal temperature and precipitation on soil water nitrate (NO₃N) concentration and leaching from winter and spring cereals cropping systems was investigated over three consecutive four-year crop rotation cycles from 1997 to 2008 in an organic farming crop rotation experiment in Denmark. Three experimental sites, varying in climate and soil type from coarse sand to sandy loam, were investigated. The experiment included experimental treatments with different rotations, manure rate and cover crop, and soil nitrate concentrations was monitored using suction cups. The effects of climate, soil and management were examined in a linear mixed model, and only parameters with significant effect (P < 0.05) were included in the final model. The model explained 61% and 47% of the variation in the square root transform of flow-weighted annual NO₃N concentration for winter and spring cereals, respectively, and 68% and 77% of the variation in the square root transform of annual NO₃N leaching for winter and spring cereals, respectively. Nitrate concentration and leaching were shown to be site specific and driven by climatic factors and crop management. There were significant effects on annual N concentration and NO₃N leaching of location, rotation, previous crop and crop cover during autumn and winter. The relative effects of temperature and precipitation differed between seasons and cropping systems. A sensitivity analysis revealed that the predicted N concentration and leaching increased with increases in temperature and precipitation.     

藻类资源在农业种植业中的应用研究进展

随着人们对海洋生物资源研究的日益关注,藻类生物资源的挖掘也越来越受到重视,近年来其在农业领域的应用和价值也日益凸显。目前,人们对藻类资源在农业中的应用研究主要集中在对藻类生物肥料和生物刺激剂的探索,即为农作物寻找新的肥料来源,但对其作用机制的研究还缺乏总结。为此,本文综述了国内外相关研究进展,重点介绍了藻类资源在农业种植业中的利用,阐述了藻类细胞及其产物在农业工程中的应用与发展,包括藻类作为生物肥料和生物刺激剂、藻类资源在农业环境修复以及农作物产品保鲜等方面的应用。此外,本文还总结了藻类资源在农业应用中的主要机理：①藻类的固碳、固氮以及解磷作用,可提高土壤营养物质含量,调节土壤微生物活力,促进植物生长;②藻类分泌的胞外聚合物有助于改善土壤荒漠化及盐碱化,降低农药污染风险和提高土壤肥料利用效率;③藻类细胞的生物吸附性有助于重金属污染土壤的修复;④海藻多糖的抑菌、抗病毒和保鲜功能等。总而言之,藻类资源在农业种植业中具有广阔的应用前景和巨大的开发价值。未来的研究应着眼于藻类细胞活性物质的促生长机理和藻类资源的田间规模评价,重视分子生物学技术的应用,挖掘更多样化的藻类应用潜力,为藻类生物质的开发和农业可持续发展提供理论依据。     

Impact of urbanization on plant diversity: A case study in built-up areas of Beijing

Urbanization is developing rapidly in the world, which seriously changes the habitat of organisms and has clearly a negative effect on biodiversity. Preservation of biodiversity is crucial in urban planning and management, which is also an important symbol for the level of greening. Problems such as scarcity of urban green space and plant species have become obstacles to the establishment of ecological friendly cities. However, coexistence of nature and modernization, as well the coordination of economic development and biodiversity, are goals that people are seeking. We have taken the builtup areas of Beijing as a study case and discussed the impacts of urbanization on plant diversity, with the support of fieldwork and SPOT remote sensing data. The results are as follows： 1） in the process of urbanization, exotic plants have been widely introduced, which has affected species composition and the proportion of native plants; it is clear that artificial green spaces always will have a lower level of plant diversity than natural green spaces; 2） functional differences of green space types partially decide their species abundance, so that plant diversity in greenbelts and streets is generally lower than in parks; 3） the spatial variety of plant diversity contributes much to the imbalance of district de- velopment and the planning of different functional zones; this variation is embodied in different ring-belts and directions; 4） habitat fragmentation also affects plant diversity to a great extent; there is a significant positive correlation between high fragmentation and low plant diversity. According our results, some suggestions are proposed, which would be suitable for the preservation of plant di- versity and ecological improvement during urbanization.     

Evaluation of Urban Development Quality Based on the Connotation of High-Quality Development: A Case Study of Guangdong Province

In this paper, based on the interpretation of the connotation of high-quality development, an urban development quality evaluation index system was established from six aspects of economic strength, the level of science and education, government management, resources and environment, the level of openness, and infrastructure, the entropy method and cluster analysis were used to conduct an empirical analysis of the quality of urban development in Guangdong Province, and relevant suggestions were proposed accordingly. The results showed that:(1) the level of science and education was the most important factor affecting the quality of urban development in Guangdong Province;(2) the quality of urban development in Guangdong Province was extremely uncoordinated;(3) cities with stronger economic strength had lower resource and environment evaluation;(4) cities of Guangdong Province could be divided into three categories: cities in a quality optimization stage, cities in a quality improvement stage, and cities in a quality lagging stage that could be further divided into three categories.     

Total Synthesis and Structural Reassignment of Laingolide A

The asymmetric total synthesis of four diastereomers of laingolide A was achieved, which led to the unambiguous assignment of the stereochemistry of the natural product. The salient features of the convergent, fully stereocontrolled approach were a copper-catalysed stereospecific Kumada-type coupling, a Julia-Kocienski olefination and an RCM/alkene migration sequence to access the desired macrocyclic enamide.     

农业发展过程中人类活动与自然环境的相互作用研究

通过阐述自然规律性法则和农民的知识水平结构两部分内容,分析了在农业发展过程中人类活动与自然环境是如何相互作用的,从而揭示出人们在农业生产过程中尊重自然、完善自我的重要性,对于当今农业向着良性、和谐方向发展具有重要的现实意义.