重庆市耕地占补平衡体系构建

耕地数量的减少和耕地质量的退化成为目前为保护18亿亩(1.2×10⁸ hm²)耕地红线所必须关注的焦点领域,为此,如何在保证耕地质量不退化的前提下,实现区域耕地总量的动态平衡,不仅是一项紧迫的政府工作,也是严肃的科学问题。论文基于现有研究成果,借助定额指标预测、相关分析和双因子调控模型等方法,结合ArcGIS的空间分析功能,从耕地现有质量和建设用地需求预测两方面体现占用耕地的保有格局,从土地开发整理潜力和占补耕地数量质量折算分析补充耕地的主要来源,进而建立重庆市耕地占补平衡体系。结果表明:到2020年重庆因建设占用将减少耕地58 856.56 hm²,土地开发整理现实新增耕地潜力达89 961.06 hm²,考虑到新增耕地的质量折算因素,新增耕地的现实潜力可达84 239.54 hm²,即是说,按照现有经济发展对建设用地的需求预测,重庆完全有能力实现耕地的占补平衡。耕地占补平衡体系的建立按照建设占用耕地与补充耕地在数量和质量上相当的要求,采用按等折算方式将其真正落到实处,对掌握重庆市实现占补平衡的最大理论潜力,具有较强的实用性和可操作性。     

Predicting Risk of Habitat Conversion in Native Temperate Grasslands

Abstract: Native grasslands that support diverse populations of birds are being converted to cropland at an increasing rate in the Prairie Pothole Region of North America. Although limited funding is currently available to mitigate losses, accurate predictions of probability of conversion would increase the efficiency of conservation measures. We studied conversion of native grassland to cropland in the Missouri Coteau region of North and South Dakota (U.S.A.) during 1989–2003. We estimated the probability of conversion of native grassland to cropland with satellite imagery and logistic regression models that predicted risk of conversion and by comparing the overlap between areas of high biological value and areas most vulnerable to conversion. Annualized probability of conversion was 0.004, and 36,540 ha of native grassland were converted to cropland during the period of our study. Our predictive models fit the data and correctly predicted 70% of observed conversions of grassland. Probability of conversion varied spatially and was correlated with landscape features like amount of surrounding grassland, slope, and soil productivity. Tracts of high biological value were not always at high risk of conversion. We concluded the most biologically valuable areas that are most vulnerable to conversion should be prioritized for conservation. This approach can be applied broadly to other systems and offers great utility for implementing conservation in areas with spatially variable biological value and probability of conversion.     

Farm size and land-use policy: An oregon case study

Farmland conversion has become an important public policy issue in the United States and in many other countries. An important part of policy considerations in farmland protection programs is the minimum parcel size for farm-related land divisions and dwelling units. The rationale for establishing size thresholds varies considerably among jurisdictions. This article reviews the policies and criteria used in the United States and several other countries, discusses the policy implications of different types of objectives, and presents the results of a case study in Oregon. The case study was the first attempt by an Oregon county to articulate a set of measurable criteria to quantify a definition of commercial agriculture for land-use applications. The criteria and data base used in the model provide a systematic procedure to process permit applications in an objective, consistent manner. The ordinance was adopted in February 1988 and has worked successfully since that time. The article summarizes permit activity under the new ordinance and comments on its effectiveness.     

广东省耕地转化及其效益变化趋势分析

本文将土地详查资料和统计资料中耕地资源的数据作了对照 ,并将耕地的变化与经济 (GDP)增长联系起来研究。结果表明 ,实际的耕地数比原有的统计数要多 ;实际减少的耕地却远远大于统计数 ;耕地减少率与GDP增长率有同步消涨的关系。可以认为 ,广东省经济主要还是资源消耗型的 ,追求经济的高速增长是耕地减少的主要驱动力     

曝气生物滤池应用于封闭循环海水养殖系统的试验研究

曝气生物滤池是封闭循环海水养殖系统的核心设备。现以封闭循环海水养殖系统中的曝气生物滤池为试验研究对象,考察了曝气生物滤池的挂膜过程及NH3-N初始质量浓度、循环流速、溶解氧（D0）、循环时间及温度对NH3-N去除效果的影响。试验表明,该曝气生物滤池的生物膜成熟快,当曝气生物滤池在正常养殖状态时．水的循环流速为130L／h可达到NH3-N最大去除率;水的循环流速为80IA可应对高浓度NH3-N负荷。在污水DO质量浓度为7．0mg／L,温度为34℃时,滤池有最大的NH3-N去除率。     

FeSO4催化剂模块的制备及对其脱硝性能影响的研究

SCR是目前广泛应用的烟气脱硝技术,本文研究的催化剂模块制备技术,对于低成本SCR催化剂的国产化开发具有重要意义.本文采用催化剂性能评价实验方法,研究了面向工程应用的FeSO4催化剂模块的制备技术,将活性成分有效地负载在陶瓷蜂窝体上.该催化剂样品在氨氮摩尔比为NH3/NOx=1和SV空速为10000h-1的真实烟气条件下,在280～380℃的温度区间内脱硝效率均在80%以上,连续运行60h后,活性并未出现明显的下降,表明该催化剂模块具备一定的抗中毒性能和机械强度.     

广东某粮食基地土壤酸性条件对地下水质量影响

研究了广东省某粮食基地土壤中的全氮和浅层地下水中氨氮的关系,发现土壤酸性—强酸性环境条件和高铁锰的第四系全新统现代滩涂沉积为农业区地下水氨氮局部污染提供了环境条件。而不合理的施用氮肥是地下水氨氮长期面状污染的主要来源。     

SNCR脱硝技术在平湖垃圾焚烧电厂的应用

文章介绍了SNCR脱硝技术原理和在平湖垃圾焚烧电厂(一期)项目上应用情况,对SNCR的工艺和需要注意的问题做出了一些说明。     

复合MBR组合工艺在生活垃圾焚烧发电厂渗滤液处理中的应用

以浙江某处理规模为100 m3/d垃圾焚烧发电厂渗滤液处理工程为例,介绍了氨吹脱+ABR+两级A/O的复合MBR组合工艺在生活垃圾焚烧厂渗滤液处理中的应用情况。复合MBR工艺对生活垃圾焚烧厂渗滤液的有机污染物和氨氮均有较高的去除效率,均在98%以上。经过该组合工艺处理后,出水水质可达到GB 8978—1996《污水综合排放标准》中三级排放标准。     

地下多层设置商场的可行性分析

本文针对地下多层商场火灾防治的难题,引出国家标准"地下三层不得设置商业"的规定,通过介绍国内外地下多层商场实例,提出了地下多层设置商业的改良措施,并以广州一家大型地下购物广场为工程实例,对该商场负三层进行了火灾危险性分析,验证了其防火分区划分及疏散通道设计,确定了人数换算系数,通过展现其消防安全优势,证明了地下多层设置...